Sample records for helicopter systems analysis

  1. Dynamics Analysis of Close-coupling Multiple Helicopters System

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhigang; Lu Tiansheng


    The particularity and practicality of harmony operations of close-coupling multiple helicopters indicate that the researches on it are urgent and necessary. Using the model that describes two hovering helicopters carrying one heavy load, an inertia coordinate system and body coordinate systems of each sub-system are established. A nonlinear force model is established too. The equilibrium computation results can be regarded as the reference control inputs of the flight control system under hovering or low-speed flight condition. After the establishment of a translation kinematics model and a posture kinematics model, a coupling dynamics model of the multiple helicopter system is set up. The results can also be regarded as the base to analyze stabilization and design a controller for a close-coupling multiple helicopters harmony operation system.

  2. Modeling, Control and Coordination of Helicopter Systems

    CERN Document Server

    Ren, Beibei; Chen, Chang; Fua, Cheng-Heng; Lee, Tong Heng


    Modeling, Control and Coordination of Helicopter Systems provides a comprehensive treatment of helicopter systems, ranging from related nonlinear flight dynamic modeling and stability analysis to advanced control design for single helicopter systems, and also covers issues related to the coordination and formation control of multiple helicopter systems to achieve high performance tasks. Ensuring stability in helicopter flight is a challenging problem for nonlinear control design and development. This book is a valuable reference on modeling, control and coordination of helicopter systems,providing readers with practical solutions for the problems that still plague helicopter system design and implementation. Readers will gain a complete picture of helicopters at the systems level, as well as a better understanding of the technical intricacies involved. This book also: Presents a complete picture of modeling, control and coordination for helicopter systems Provides a modeling platform for a general class of ro...

  3. Proposed Wind Turbine Aeroelasticity Studies Using Helicopter Systems Analysis (United States)

    Ladkany, Samaan G.


    Advanced systems for the analysis of rotary wing aeroelastic structures (helicopters) are being developed at NASA Ames by the Rotorcraft Aeromechanics Branch, ARA. The research has recently been extended to the study of wind turbines, used for electric power generation Wind turbines play an important role in Europe, Japan & many other countries because they are non polluting & use a renewable source of energy. European countries such as Holland, Norway & France have been the world leaders in the design & manufacture of wind turbines due to their historical experience of several centuries, in building complex wind mill structures, which were used in water pumping, grain grinding & for lumbering. Fossil fuel cost in Japan & in Europe is two to three times higher than in the USA due to very high import taxes. High fuel cost combined with substantial governmental subsidies, allow wind generated power to be competitive with the more traditional sources of power generation. In the USA, the use of wind energy has been limited mainly because power production from wind is twice as expensive as from other traditional sources. Studies conducted at the National Renewable Energy Laboratories (NREL) indicate that the main cost in the production of wind turbines is due to the materials & the labor intensive processes used in the construction of turbine structures. Thus, for the US to assume world leadership in wind power generation, new lightweight & consequently very flexible wind turbines, that could be economically mass produced, would have to be developed [4,5]. This effort, if successful, would result in great benefit to the US & the developing nations that suffer from overpopulation & a very high cost of energy.

  4. Minor Component Analysis-based Landing Forecast System for Ship-borne Helicopter

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bo,; SHI Ai-guo; WAN Lin; YANG Bao-zhang


    The general structure of ship-borne helicopter landing forecast system is presented, and a novel ship motion prediction model based on minor component analysis (MCA) is built up to improve the forecast effectiveness. To validate the feasibility of this landing forecast system, time series for the roll, pitch and heave are generated by simulation and then forecasted based on MCA. Simulation results show that ship-borne helicopters can land safely in higher sea condition while carrying on rescue or replenishment tasks at sea in terms of the landing forecast system.

  5. Sensor selection of helicopter transmission systems based on physical model and sensitivity analysis

    Institute of Scientific and Technical Information of China (English)

    Lyu Kehong; Tan Xiaodong; Liu Guanjun; Zhao Chenxu


    In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators (CIs) are presented, and the optimal CIs set is selected by comparing their test statistics according to Mann-Kendall test. Afterwards, the selected CIs are used to generate a health indicator (HI) through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitor-ing of helicopter transmission systems, and it is effective to reduce the test cost and improve the system’s reliability.

  6. Sensor selection of helicopter transmission systems based on physical model and sensitivity analysis

    Directory of Open Access Journals (Sweden)

    Lyu Kehong


    Full Text Available In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators (CIs are presented, and the optimal CIs set is selected by comparing their test statistics according to Mann–Kendall test. Afterwards, the selected CIs are used to generate a health indicator (HI through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitoring of helicopter transmission systems, and it is effective to reduce the test cost and improve the system’s reliability.

  7. Sensitivity analysis of helicopter IMC decelerating steep approach and landing performance to navigation system parameters (United States)

    Karmali, M. S.; Phatak, A. V.


    Results of a study to investigate, by means of a computer simulation, the performance sensitivity of helicopter IMC DSAL operations as a function of navigation system parameters are presented. A mathematical model representing generically a navigation system is formulated. The scenario simulated consists of a straight in helicopter approach to landing along a 6 deg glideslope. The deceleration magnitude chosen is 03g. The navigation model parameters are varied and the statistics of the total system errors (TSE) computed. These statistics are used to determine the critical navigation system parameters that affect the performance of the closed-loop navigation, guidance and control system of a UH-1H helicopter.

  8. Sensitivity analysis of helicopter IMC decelerating steep approach and landing performance to navigation system parameters. [Instrument Meteorological Conditions (United States)

    Karmali, M. S.; Phatak, A. V.; Bull, J. S.; Peach, L. L.; Demko, P. S.


    The present investigation is concerned with a sensitivity analysis of the Decelerated Steep Approach and Landing (DSAL) maneuver to on-board and ground-based navigation system parameters. The Instrument Meteorological Conditions (IMC) DSAL maneuver involves decelerating to zero range rate while tracking the localizer and glideslope. The considered study investigated the performance of the navigation systems using Constant Deceleration Profile (CDP) guidance and a six degrees glideslope trajectory. A closed-loop computer simulation of the UH1H helicopter DSAL system was developed for the sensitivity analysis. Conclusions on system performance parameter sensitivity are discussed.

  9. Feasibility study for ergonomic analysis and design of future helicopter cockpit systems (United States)

    Hawkins, H. L.


    The Army's light scout-attack helicopters (LHXs), planned for deployment in the 1990's, will fly nap-of-the-earth (NOE) missions in high threat environments, often under poor visibility and adverse atmospheric conditions, and probably with a one man crew. A procedure for the analysis of pilot workload that will identify and explicate the main characteristics of those LHX mission components holding overload potential is described. A principled, in-depth, explication of the cognitive demans of LHX piloting is essential to any effective effort to address the human factors issues. A task-analytic procedure that will yield the detail and organizstion needed to achieve these goals is examined.

  10. Polyspectral signal analysis techniques for condition based maintenance of helicopter drive-train system (United States)

    Hassan Mohammed, Mohammed Ahmed

    For an efficient maintenance of a diverse fleet of air- and rotorcraft, effective condition based maintenance (CBM) must be established based on rotating components monitored vibration signals. In this dissertation, we present theory and applications of polyspectral signal processing techniques for condition monitoring of critical components in the AH-64D helicopter tail rotor drive train system. Currently available vibration-monitoring tools are mostly built around auto- and cross-power spectral analysis which have limited performance in detecting frequency correlations higher than second order. Studying higher order correlations and their Fourier transforms, higher order spectra, provides more information about the vibration signals which helps in building more accurate diagnostic models of the mechanical system. Based on higher order spectral analysis, different signal processing techniques are developed to assess health conditions of different critical rotating-components in the AH-64D helicopter drive-train. Based on cross-bispectrum, quadratic nonlinear transfer function is presented to model second order nonlinearity in a drive-shaft running between the two hanger bearings. Then, quadratic-nonlinearity coupling coefficient between frequency harmonics of the rotating shaft is used as condition metric to study different seeded shaft faults compared to baseline case, namely: shaft misalignment, shaft imbalance, and combination of shaft misalignment and imbalance. The proposed quadratic-nonlinearity metric shows better capabilities in distinguishing the four studied shaft settings than the conventional linear coupling based on cross-power spectrum. We also develop a new concept of Quadratic-Nonlinearity Power-Index spectrum, QNLPI(f), that can be used in signal detection and classification, based on bicoherence spectrum. The proposed QNLPI(f) is derived as a projection of the three-dimensional bicoherence spectrum into two-dimensional spectrum that

  11. NASTRAN data generation of helicopter fuselages using interactive graphics. [preprocessor system for finite element analysis using IBM computer (United States)

    Sainsbury-Carter, J. B.; Conaway, J. H.


    The development and implementation of a preprocessor system for the finite element analysis of helicopter fuselages is described. The system utilizes interactive graphics for the generation, display, and editing of NASTRAN data for fuselage models. It is operated from an IBM 2250 cathode ray tube (CRT) console driven by an IBM 370/145 computer. Real time interaction plus automatic data generation reduces the nominal 6 to 10 week time for manual generation and checking of data to a few days. The interactive graphics system consists of a series of satellite programs operated from a central NASTRAN Systems Monitor. Fuselage structural models including the outer shell and internal structure may be rapidly generated. All numbering systems are automatically assigned. Hard copy plots of the model labeled with GRID or elements ID's are also available. General purpose programs for displaying and editing NASTRAN data are included in the system. Utilization of the NASTRAN interactive graphics system has made possible the multiple finite element analysis of complex helicopter fuselage structures within design schedules.

  12. Study of the helicopter blade running elevation measurement system

    Institute of Scientific and Technical Information of China (English)


    Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter's security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, the design of the measurement system and analysis of the measurement precision.

  13. General equilibrium characteristics of a dual-lift helicopter system (United States)

    Cicolani, L. S.; Kanning, G.


    The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.

  14. Helicopter Propulsion Systems (United States)


    r " for the introduction of the gas turbine with its high horsepower output per unit weighL .nd volume, good efficiency, and its virtually unlimited...approach, plus the use of maximum continuous limits for the drive system, would virtually eliminate the pilot’s concern for exceeding turbine libro . Pour cola, ii faut connaitra parfaitemont les regimes do survitossos (d~rives do r~gulation, etc...) rencontrts sur h6licopto~re en

  15. Flight Testing and Real-Time System Identification Analysis of a UH-60A Black Hawk Helicopter with an Instrumented External Sling Load (United States)

    McCoy, Allen H.


    Helicopter external air transportation plays an important role in today's world. For both military and civilian helicopters, external sling load operations offer an efficient and expedient method of handling heavy, oversized cargo. With the ability to reach areas otherwise inaccessible by ground transportation, helicopter external load operations are conducted in industries such as logging, construction, and fire fighting, as well as in support of military tactical transport missions. Historically, helicopter and load combinations have been qualified through flight testing, requiring considerable time and cost. With advancements in simulation and flight test techniques there is potential to substantially reduce costs and increase the safety of helicopter sling load certification. Validated simulation tools make possible accurate prediction of operational flight characteristics before initial flight tests. Real time analysis of test data improves the safety and efficiency of the testing programs. To advance these concepts, the U.S. Army and NASA, in cooperation with the Israeli Air Force and Technion, under a Memorandum of Agreement, seek to develop and validate a numerical model of the UH-60 with sling load and demonstrate a method of near real time flight test analysis. This thesis presents results from flight tests of a U.S. Army Black Hawk helicopter with various external loads. Tests were conducted as the U.S. first phase of this MOA task. The primary load was a container express box (CONEX) which contained a compact instrumentation package. The flights covered the airspeed range from hover to 70 knots. Primary maneuvers were pitch and roll frequency sweeps, steps, and doublets. Results of the test determined the effect of the suspended load on both the aircraft's handling qualities and its control system's stability margins. Included were calculations of the stability characteristics of the load's pendular motion. Utilizing CIFER(R) software, a method for near

  16. A cable detection lidar system for helicopters (United States)

    Grossmann, Benoist; Capbern, Alain; Defour, Martin; Fertala, Remi


    Helicopters in low-level flight are endangered by power lines or telephone wires, especially when flying at night and under poor visibility conditions. In order to prevent 'wire strike', Thomson has developed a lidar system consisting of a pulsed diode laser emitting in the near infrared region (lambda = 0.9 microns). The HOWARD (Helicopter Obstacle Warning and Detection) System utilizes a high repetition rate diode laser (PRE = 20 KHz) along with counter-rotating prisms for laser beam deflection with a total field of view of 30 degrees. This system was successfully field tested in 1991. HOWARD can detect one inch wires at ranges up to 200 meters. We are presently in the process of developing a flyable compact lidar system capable of detection ranges in the order of 400 meters.

  17. Modeling, Estimation, and Control of Helicopter Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten

    This thesis treats the subject of autonomous helicopter slung load flight and presents the reader with a methodology describing the development path from modeling and system analysis over sensor fusion and state estimation to controller synthesis. The focus is directed along two different....... To enable slung load flight capabilities for general cargo transport, an integrated estimation and control system is developed for use on already autonomous helicopters. The estimator uses vision based updates only and needs little prior knowledge of the slung load system as it estimates the length...... of the suspension system together with the system states. The controller uses a combined feedforward and feedback approach to simultaneously prevent exciting swing and to actively dampen swing in the slung load. For the mine detection application an estimator is developed that provides full system state information...

  18. Helicopter controllability


    Carico, Dean


    Approved for public release; distribution is unlimited The concept of helicopter controllability is explained. A background study reviews helicopter development in the U.S. General helicopter configurations, linearized equations of motion, stability, and piloting requirements are discussed. Helicopter flight controls, handling qualities, and associated specification are reviewed. Analytical, simulation and flight test methods for evaluating helicopter automatic flight control systems ar...

  19. Analysis of muscle fatigue in helicopter pilots. (United States)

    Balasubramanian, Venkatesh; Dutt, Ashwani; Rai, Shobhit


    Helicopter pilots espouse ergonomically unfavourable postures and endure vibration which result in low back pain. The objective of this study was to investigate the effects of a helicopter flight on pilots back and shoulder muscles using surface Electromyography (sEMG) analysis. This study also correlates low back pain symptoms from Rehabilitation Bioengineering Group Pain Scale (RBGPS) questionnaire with muscle fatigue rates obtained. RBGPS was administered on 20 Coast Guard helicopter pilots. sEMG was acquired before and after flight from erector spinae and trapezius muscles in 8 of these 20 pilots. Statistical analysis of time and frequency domain parameters indicated significant fatigue in right trapezius muscle due to flying. Muscle fatigue correlated with average duration of flight (r² = 0.913), total service as pilot (r² = 0.825), pain (r² = 0.463) and total flying hours (r² = 0.507). However, muscle fatigue weakly correlated with Body Mass Index (BMI) (r² = 0.000144) and age (r² = 0.033).

  20. System-Integrated Finite Element Analysis of a Full-Scale Helicopter Crash Test with Deployable Energy Absorbers (United States)

    Annett, Martin S.; Polanco, Michael A.


    A full-scale crash test of an MD-500 helicopter was conducted in December 2009 at NASA Langley's Landing and Impact Research facility (LandIR). The MD-500 helicopter was fitted with a composite honeycomb Deployable Energy Absorber (DEA) and tested under vertical and horizontal impact velocities of 26-ft/sec and 40-ft/sec, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of a system integrated finite element model. In preparation for the full-scale crash test, a series of sub-scale and MD-500 mass simulator tests was conducted to evaluate the impact performances of various components, including a new crush tube and the DEA blocks. Parameters defined within the system integrated finite element model were determined from these tests. The objective of this paper is to summarize the finite element models developed and analyses performed, beginning with pre-test predictions and continuing through post-test validation.

  1. Higher harmonic control analysis for vibration reduction of helicopter rotor systems (United States)

    Nguyen, Khanh Q.


    An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor

  2. Helicopter

    NARCIS (Netherlands)

    Van Holten, T.


    The invention relates to a helicopter provided with a rotor with at least one rotor blade (5), wherein drive means are provided for actively moving the or each rotor blade up and down during rotation of the rotor, in particular about a flapping hinge (8) thereof, so that moments, applied by the roto

  3. Vision Aided State Estimation for Helicopter Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten; Bendtsen, Jan Dimon; la Cour-Harbo, Anders


    This paper presents the design and verification of a state estimator for a helicopter based slung load system. The estimator is designed to augment the IMU driven estimator found in many helicopter UAV s and uses vision based updates only. The process model used for the estimator is a simple 4 st...

  4. Full State Estimation for Helicopter Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon


    This paper presents the design of a state estimator system for a generic helicopter based slung load system. The estimator is designed to deliver full rigid body state information for both helicopter and load and is based on the unscented Kalman filter. Two different approaches are investigated......: One based on a parameter free kinematic model and one based on a full aerodynamic helicopter and slung load model. The kinematic model approach uses acceleration and rate information from two Inertial Measurement Units, one on the helicopter and one on the load, to drive a simple kinematic model....... A simple and effective virtual sensor method is developed to maintain the constraints imposed by the wires in the system. The full model based approach uses a complex aerodynamical model to describe the helicopter together with a generic rigid body model. This rigid body model is based on a redundant...

  5. Full State Estimation for Helicopter Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon

    This paper presents the design of a state estimator system for a generic helicopter based slung load system. The estimator is designed to deliver full rigid body state information for both helicopter and load and is based on the unscented Kalman filter. Two different approaches are investigated......: One based on a parameter free kinematic model and one based on a full aerodynamic helicopter and slung load model. The kinematic model approach uses acceleration and rate information from two Inertial Measurement Units, one on the helicopter and one on the load, to drive a simple kinematic model....... A simple and effective virtual sensor method is developed to maintain the constraints imposed by the wires in the system. The full model based approach uses a complex aerodynamical model to describe the helicopter together with a generic rigid body model. This rigid body model is based on a redundant...

  6. Principal Components Analysis of Triaxial Vibration Data From Helicopter Transmissions (United States)

    Tumer, Irem Y.; Huff, Edward M.


    Research on the nature of the vibration data collected from helicopter transmissions during flight experiments has led to several crucial observations believed to be responsible for the high rates of false alarms and missed detections in aircraft vibration monitoring systems. This work focuses on one such finding, namely, the need to consider additional sources of information about system vibrations. In this light, helicopter transmission vibration data, collected using triaxial accelerometers, were explored in three different directions, analyzed for content, and then combined using Principal Components Analysis (PCA) to analyze changes in directionality. In this paper, the PCA transformation is applied to 176 test conditions/data sets collected from an OH58C helicopter to derive the overall experiment-wide covariance matrix and its principal eigenvectors. The experiment-wide eigenvectors. are then projected onto the individual test conditions to evaluate changes and similarities in their directionality based on the various experimental factors. The paper will present the foundations of the proposed approach, addressing the question of whether experiment-wide eigenvectors accurately model the vibration modes in individual test conditions. The results will further determine the value of using directionality and triaxial accelerometers for vibration monitoring and anomaly detection.

  7. Adaptive Control System for Autonomous Helicopter Slung Load Operations

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon


    system on the helicopter that measures the position of the slung load. The controller is a combined feedforward and feedback scheme for simultaneous avoidance of swing excitation and active swing damping. Simulations and laboratory flight tests show the effectiveness of the combined control system......This paper presents design and verification of an estimation and control system for a helicopter slung load system. The estimator provides position and velocity estimates of the slung load and is designed to augment existing navigation in autonomous helicopters. Sensor input is provided by a vision......, yielding significant load swing reduction compared to the baseline controller....

  8. Swing Damping for Helicopter Slung Load Systems using Delayed Feedback

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon


    of swing. The design of the delayed feedback controller is presented as an optimization problem which gives the possibility of an automated design process. Simulations and flight test verifications of the control system on two different autonomous helicopters are presented and it is shown how a significant......This paper presents the design and verification of a swing reducing controller for helicopter slung load systems using intentional delayed feedback. It is intended for augmenting a trajectory tracking helicopter controller and thereby improving the slung load handing capabilities for autonomous...... helicopters. The delayed feedback controller is added to actively reduce oscillations of the slung load by improving the damping of the slung load pendulum modes. Furthermore, it is intended for integration with a feedforward control scheme based on input shaping for concurrent avoidance and dampening...

  9. Preliminary Analysis of Helicopter Options to Support Tunisian Counterterrorism Operations (United States)


    results of the current analysis and in Mouton et al., 2015, is the relative cost -effectiveness between the CH-47D and the Mi-17v5. In the previous...helicopters from Sikorsky to fulfill a number of roles in counterterrorism operations. Rising costs and delays in delivery raised the question of...whether other cost -effective options exist to meet Tunisia’s helicopter requirement. Approach Our team conducted a preliminary assessment of

  10. Vision Aided State Estimation for Helicopter Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten; Bendtsen, Jan Dimon; la Cour-Harbo, Anders


    This paper presents the design and verification of a state estimator for a helicopter based slung load system. The estimator is designed to augment the IMU driven estimator found in many helicopter UAV s and uses vision based updates only. The process model used for the estimator is a simple 4 st...... the estimator is verified using flight data and it is shown that it is capable of reliably estimating the slung load states....

  11. Development of adaptive helicopter seat systems for aircrew vibration mitigation (United States)

    Chen, Yong; Wickramasinghe, Viresh; Zimcik, David G.


    Helicopter aircrews are exposed to high levels of whole body vibration during flight. This paper presents the results of an investigation of adaptive seat mount approaches to reduce helicopter aircrew whole body vibration levels. A flight test was conducted on a four-blade helicopter and showed that the currently used passive seat systems were not able to provide satisfactory protection to the helicopter aircrew in both front-back and vertical directions. Long-term exposure to the measured whole body vibration environment may cause occupational health issues such as spine and neck strain injuries for aircrew. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew body. For proof-of-concept demonstration, a miniature modal shaker was properly aligned between the cabin floor and the seat frame to provide adaptive actuation authority. Adaptive control laws were developed to reduce the vibration transmitted to the aircrew body, especially the helmet location in order to minimize neck and spine injuries. Closed-loop control test have been conducted on a full-scale helicopter seat with a mannequin configuration and a large mechanical shaker was used to provide representative helicopter vibration profiles to the seat frame. Significant vibration reductions to the vertical and front-back vibration modes have been achieved simultaneously, which verified the technical readiness of the adaptive mount approach for full-scale flight test on the vehicle.

  12. Design and implementation of a GPS-aided inertial navigation system for a helicopter UAV (United States)

    Kastelan, David R.

    Helicopter unmanned aerial vehicles (UAVs) benefit from vertical takeoff and landing, hover, low-speed, and cruising flight capabilities. This versatility has the expense of nonlinear, unstable, and underactuated system dynamics. These challenges and numerous potential applications make the helicopter UAV an interesting testbed for nonlinear control. A platform for such development has been established in the Applied Nonlinear Controls Lab (ANCL). A miniature helicopter was augmented with a manual/autonomous takeover system and the ANCL Avionics. This payload contains a global positioning system (GPS) receiver, inertial sensors, and communications and computing hardware. Allan variance analysis of inertial sensor data enabled the derivation of a GPS-aided inertial navigation system that was implemented on the ANCL Avionics. This extended Kalman filter (EKF)-based algorithm estimates vehicle position, velocity, and attitude necessary for system identification tasks and control system feedback. Performance validation of this algorithm was demonstrated in simulation and in experimental ground and flight tests.

  13. Dynamic analysis of multimesh-gear helicopter transmissions (United States)

    Choy, Fred K.; Townsend, Dennis P.; Oswald, Fred B.


    A dynamic analysis of multimesh-gear helicopter transmission systems was performed by correlating analytical simulations with experimental investigations. The two computer programs used in this study, GRDYNMLT and PGT, were developed under NASA/Army sponsorship. Parametric studies of the numerical model with variations on mesh damping ratios, operating speeds, tip-relief tooth modifications, and tooth-spacing errors were performed to investigate the accuracy, application, and limitations of the two computer programs. Although similar levels of dynamic loading were predicted by both programs, the computer code GRDYNMLT was found to be superior and broader in scope. Results from analytical work were also compared with experimental data obtained from the U.S. Army's UH-60A Black Hawk 2240-kW (3000-hp) class, twin-engine helicopter transmission tested at the NASA Lewis Research Center. Good correlation in gear stresses was obtained between the analytical model simulated by GRDYNMLT and the experimental measurements. More realistic mesh damping can be predicted through experimental data correlation.

  14. Analysis of Vibratory Excitation of Gear Systems as a Contributor to Aircraft Interior Noise. [helicopter cabin noise (United States)

    Mark, W. D.


    Application of the transfer function approach to predict the resulting interior noise contribution requires gearbox vibration sources and paths to be characterized in the frequency domain. Tooth-face deviations from perfect involute surfaces were represented in terms of Legendre polynomials which may be directly interpreted in terms of tooth-spacing errors, mean and random deviations associated with involute slope and fullness, lead mismatch and crowning, and analogous higher-order components. The contributions of these components to the spectrum of the static transmission error is discussed and illustrated using a set of measurements made on a pair of helicopter spur gears. The general methodology presented is applicable to both spur and helical gears.

  15. Numerical Analysis of Helicopter Rotor Hovering in Close Proximity to the Ground with a Wall (United States)

    Itoga, Noriaki; Iboshi, Naohiro; Horimoto, Mitsumasa; Saito, Shigeru; Tanabe, Yasutada

    In rescue operations and emergency medical services, helicopters are frequently required to operate near the ground with obstacles such as buildings and sidewalls of highway. In this paper, numerical analysis of helicopter rotor hovering in close proximity to the ground with an obstacle is done by solving unsteady 3D compressible Euler equations with an overlapped grid system. The obstacle is simulated by a wall vertically set up on the ground. The parameters for numerical analysis are the rotor height and distance from the rotor-hub-center to the wall. The effects of combinations of these parameters on the flowfields around the rotor, inflow distributions on the rotor disc and behaviors of blade flapping motion are discussed. It is also clarified the cause that the helicopter rotor hovering in close proximity to the ground with a wall does not have the enough ground effect depending on the combinations of these parameters.

  16. Helicopter human factors (United States)

    Hart, Sandra G.


    The state-of-the-art helicopter and its pilot are examined using the tools of human-factors analysis. The significant role of human error in helicopter accidents is discussed; the history of human-factors research on helicopters is briefly traced; the typical flight tasks are described; and the noise, vibration, and temperature conditions typical of modern military helicopters are characterized. Also considered are helicopter controls, cockpit instruments and displays, and the impact of cockpit design on pilot workload. Particular attention is given to possible advanced-technology improvements, such as control stabilization and augmentation, FBW and fly-by-light systems, multifunction displays, night-vision goggles, pilot night-vision systems, night-vision displays with superimposed symbols, target acquisition and designation systems, and aural displays. Diagrams, drawings, and photographs are provided.

  17. Efficient sensitivity analysis and optimization of a helicopter rotor (United States)

    Lim, Joon W.; Chopra, Inderjit


    Aeroelastic optimization of a system essentially consists of the determination of the optimum values of design variables which minimize the objective function and satisfy certain aeroelastic and geometric constraints. The process of aeroelastic optimization analysis is illustrated. To carry out aeroelastic optimization effectively, one needs a reliable analysis procedure to determine steady response and stability of a rotor system in forward flight. The rotor dynamic analysis used in the present study developed inhouse at the University of Maryland is based on finite elements in space and time. The analysis consists of two major phases: vehicle trim and rotor steady response (coupled trim analysis), and aeroelastic stability of the blade. For a reduction of helicopter vibration, the optimization process requires the sensitivity derivatives of the objective function and aeroelastic stability constraints. For this, the derivatives of steady response, hub loads and blade stability roots are calculated using a direct analytical approach. An automated optimization procedure is developed by coupling the rotor dynamic analysis, design sensitivity analysis and constrained optimization code CONMIN.

  18. Aeromechanical Analysis of a Smart Helicopter Rotor in Forward Flight

    Directory of Open Access Journals (Sweden)

    Jacopo Serafini


    Full Text Available This paper deals with a smart system integrated into a helicopter blade aimed at giving an anhedral shape to the blade tip region to alleviate the blade-vortex interaction phenomenon that may cause reduced helicopter performance in terms of noise and vibrations. The blade tip morphing is obtained through the joint action of a magneto-rheological fluid (MRF device, a shape-memory alloy ribbons- based (SMA device and a set of concentrated masses properly distributed spanwise. The presence of this smart actuator (particularly the concentrated masses inside the blades modifies the aeromechanical behaviour of the rotor and may be detrimental in terms of hub vibratory loads, pitch control effectiveness and aeroelastic stability. Following a previous literature work concerning with the effectiveness of the smart actuated rotor in hovering conditions, the present paper focuses on the aeromechanical effects due to the inclusion of the smart device in a four-bladed helicopter rotor in forward flight where blade morphing is not needed. Aim of this work is to investigate on the compatibility of the smart system with the required aeromechanical performance of the rotor, highlighting the feasibility of its application on helicopters.

  19. Classification Trees and the Analysis of Helicopter Vibration Data


    Larson, Harold J.


    Health and Usage Monitoring Systems are receiving a great deal of interest, in an attempt to increase the safety and operational readiness of helicopters, and to minimize maintenance costs. These systems monitor (and can record) various flight parameters, pilot conversations, engine exhaust debris, metallic chip detector levels in the lubrication system, rotor track and balance, as well as vibration levels at selected locations throughout the airframe and the power drive system. Vibration lev...

  20. Analysis of potential helicopter vibration reduction concepts (United States)

    Landgrebe, A. J.; Davis, M. W.


    Several recent helicopter vibration reduction research programs are described. Results of studies of blade design parameters in rotor vibratory response and of an advanced blade design for reduced vibration are examined. An optimization approach to develop a general automated procedure for rotor blade design is described, and analytical results for an articulated rotor operating at a steady 160 kt flight condition are reported. The use of a self-adaptive controller to implement higher harmonic control in closed-loop fashion is addressed, and a computer simulation used to evaluate and compare the performance of alternative algorithms included in the generic active controller is discussed. Results are presented for steady level flight conditions, short-duration maneuvers, blade stresses and rotor performance, blade-appended aeroelastic devices, vibratory airloads, wake-induced blade airloads, and airloads from blade motions, the interaction of rotor and fuselage, and the interaction of rotor and empennage.

  1. Design of fault tolerant control system for individual blade control helicopters (United States)

    Tamayo, Sergio

    This dissertation presents the development of a fault tolerant control scheme for helicopters fitted with individually controlled blades. This novel approach attempts to improve fault tolerant capabilities of helicopter control system by increasing control redundancy using additional actuators for individual blade input and software re-mixing to obtain nominal or close to nominal conditions under failure. An advanced interactive simulation environment has been developed including modeling of sensor failure, swashplate actuator failure, individual blade actuator failure, and blade delamination to support the design, testing, and evaluation of the control laws. This simulation environment is based on the blade element theory for the calculation of forces and moments generated by the main rotor. This discretized model allows for individual blade analysis, which in turn allows measuring the consequences of a stuck blade, or loss of the surface area of the blade itself, with respect to the dynamics of the whole helicopter. The control laws are based on non-linear dynamic inversion and artificial neural network augmentation, which is a mix of linear and nonlinear methods that compensates for model inaccuracies due to linearization or failure. A stability analysis based on the Lyapunov function approach has shown that bounded tracking error is guaranteed, and under specific circumstances, global stability is guaranteed as well. An analysis over the degrees of freedom of the mechanical system and its impact over the helicopter handling qualities is also performed to measure the degree of redundancy achieved with the addition of individual blade actuators as compared to a classic swashplate helicopter configuration. Mathematical analysis and numerical simulation, using reconfiguration of the individual blade control under failure have shown that this control architecture can potentially improve the survivability of the aircraft and reduce pilot workload under failure

  2. Direct Self-Repairing Control for Quadrotor Helicopter Attitude Systems

    Directory of Open Access Journals (Sweden)

    Huiliao Yang


    Full Text Available A quadrotor helicopter with uncertain actuator faults, such as loss of effectiveness and lock-in-place, is studied in this paper. An adaptive fuzzy sliding mode controller based on direct self-repairing control is designed for such nonlinear system to track the desired output signal, when any actuator of this quadrotor helicopter is loss of effectiveness or stuck at some place. Moreover, using the Lyapunov stability theory, the stability of the whole system and the convergence of the tracking error can be guaranteed. Finally, the availability of the proposed method is verified by simulation on 3-DOF hover to ensure that the system performance under faulty conditions can be quickly recovered to its normal level. And this proposed method is also proved to be better than that of LQR through simulation.


    Institute of Scientific and Technical Information of China (English)



    In order to obtain the characteristics of the torsional vibration of a helicopter transmission system, a calculation of the torsional vibration is carried out. The transmission system is divided into the subsystems of shaft segment and disks, based on a simplified structure of the transmission system. The solution of the torsional vibration can be obtained using the modal superposition method, The torsional frequency response function of a helicopter transmission system is analyzed. The result shows that there is the extreme value of amplitude of a torsional frequency response function near low order torsional nature frequencies. When the same order torsional resonance is produced in a helicopter transmission system by excitation parts with different frequencies, the rotation speed of an engine is unequal. The larger transmission ratio from an engine to excitation parts is, the higher rotation speed of an engine is. When torsional resonance of a transmission system is caused by a rotor, the rotation speed of an engine is the largest in the same order torsional resonance.%为了获得直升机传动系统扭转振动的特性,对直升机传动系统的扭转振动进行了计算和分析。在简化传动系统结构的基础上,将直升机传动系统划分为若干个轴段和圆盘的子系统,根据振型叠加原理,得到了直升机传动系统扭转振动的解,分析了传动系统的扭转频响函数。结果表明:传动系统扭转频响函数幅值的峰值出现在低阶固有频率附近;不同频率激振源的部件引起传动系统同阶扭转共振时,发动机的转速不等,发动机到激振源部件的传动比大,发动机的转速高;在同阶扭转共振中,桨叶引起传动系统扭转共振时,发动机的转速最高。

  4. Response of the skeletal system to helicopter-unique vibration. (United States)

    Gearhart, J R


    An 18-month prospective skeletal system study was conducted on flying and nonflying personnel relative to chronic low-frequency vibration as experienced in helicopter flight. The aviators were initial entry students in rotary-wing training while the non-flying participants were beginning basic military training. Comparisons were made on the basis of anthropometric measurements, radiological studies, and bone mineral density changes as measured by photon absorption. The bone mineral densitometry showed no significant variation in the aviator group. A short-term 10% demineralization of the distal ulna in the non-flying group was noted immediately following the physical training. The final bone mineral density of basic training subjects returned to the initial level 18 months after the physical training. It was concluded that the helicopter aircrew members under study were exposed to levels of vibration below the threshold of vibration required to produce a measurable change in the skeletal system.

  5. Missile Captive Carry Monitoring and Helicopter Identification Using a Capacitive Microelectromechanical Systems Accelerometer

    Energy Technology Data Exchange (ETDEWEB)

    Hatchell, Brian K.; Mauss, Fredrick J.; Amaya, Ivan A.; Skorpik, James R.; Silvers, Kurt L.; Marotta, Steve


    Military missiles are exposed to many sources of mechanical vibration that can affect system reliability, safety, and mission effectiveness. The U. S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC) has been developing missile health monitoring systems to assess and improve reliability, reduce life cycle costs, and increase system readiness. One of the most significant exposures to vibration occurs when the missile is being carried by a helicopter or other aviation platform, which is a condition known as captive carry. Recording the duration of captive carry exposure during the missile’s service life can enable the implementation of predictive maintenance and resource management programs. Since the vibration imparted by each class of helicopter varies in frequency and amplitude, tracking the vibration exposure from each helicopter separately can help quantify the severity and harmonic content of the exposure. Under the direction of AMRDEC staff, engineers at the Pacific Northwest National Laboratory have developed a Captive Carry Health Monitor (CCHM) for the Hellfire II missile. The CCHM is an embedded usage monitoring device installed on the outer skin of the Hellfire II missile to record the cumulative hours the host missile has been in captive carry mode. To classify the vibration by class of helicopter, the CCHM analyzes the amplitude and frequency content of the vibration with the Goertzel algorithm to detect the presence of distinctive rotor harmonics. Cumulative usage data are accessible in theater from an external display; monthly usage histograms are accessible through an internal download connector. This paper provides an overview of the CCHM electrical and package design, describes field testing and data analysis techniques used to monitor captive carry identify and the class of helicopter, and discusses the potential application of missile health and usage data for real-time reliability analysis and fleet management.

  6. Vibration analysis of the SA349/2 helicopter (United States)

    Heffernan, Ruth; Precetti, Dominique; Johnson, Wayne


    Helicopter airframe vibration is examined using calculations and measurements for the SA349/2 research helicopter. The hub loads, which transmit excitations to the fuselage, are predicted using a comprehensive rotorcraft analysis and correlated with measuring hub loads. The predicted and measured hub loads are then coupled with finite element models representing the SA349/2 fuselage. The resulting vertical acceleration at the pilot seat is examined. Adjustments are made to the airframe structural models to examine the sensitivity of predicted vertical acceleration to the model. Changes of a few percent to the damping and frequency of specific models lead to large reductions in predicted vibration, and to major improvements in the correlations with measured pilot-seat vertical acceleration.

  7. Analysis and correlation of SA349/2 helicopter vibration (United States)

    Heffernan, Ruth; Precetti, Dominique; Johnson, Wayne


    Helicopter airframe vibration is examined using calculation and measurements for the SA349/2 research helicopter. The hub loads, which transmit excitation to the fuselage, are predicted using a comprehensive rotorcraft analysis and correlated with measured hub loads. The predicted and measured hub loads are then coupled with finite element models representing the SA349/2 fuselage. The resulting vertical acceleration at the pilot seat is examined. Adjustments are made to the airframe structural models to examine the sensitivity of predicted vertical acceleration to the model. Changes of a few percent to the damping and frequency of specific modes lead to large reductions in predicted vibration and to major improvements in the correlations with measured pilot seat vertical acceleration.

  8. Impact Analysis on the Removal of Filter/Monitors from USN/USMC Helicopter in Flight Refueling Systems (United States)


    water/contamination from being introduced into the airframe fuel system during HIFR from the air capable ships. Although fuel quality assurance...purposes, and in emergency situations to avoid ditching (e.g. a fouled deck, deck unsuitable for landing, aircraft too heavy, etc). At most

  9. Classification analysis of vibration data from SH-60B Helicopter Transmission Test Facility


    Anderson, Gregory L.


    Approved for public release; distribution is unlimited Health and Usage Monitoring Systems (HUMS) is an emerging technology in helicopter aviation. The United States Navy is evaluating its viability for use on its helicopter fleet. HUMS uses sensors placed throughout the helicopter to monitor and record vibration signals and numerous other aircraft operating parameters. This thesis evaluates the vibration signals recorded by a HUMS system using a statistical technique called tree structure...

  10. Dynamic Analysis of a Helicopter Rotor by Dymore Program (United States)

    Doğan, Vedat; Kırca, Mesut

    The dynamic behavior of hingeless and bearingless blades of a light commercial helicopter which has been under design process at ITU (İstanbul Technical University, Rotorcraft Research and Development Centre) is investigated. Since the helicopter rotor consists of several parts connected to each other by joints and hinges; rotors in general can be considered as an assembly of the rigid and elastic parts. Dynamics of rotor system in rotation is complicated due to coupling of elastic forces (bending, torsion and tension), inertial forces, control and aerodynamic forces on the rotor blades. In this study, the dynamic behavior of the rotor for a real helicopter design project is analyzed by using DYMORE. Blades are modeled as elastic beams, hub as a rigid body, torque tubes as rigid bodies, control links as rigid bodies plus springs and several joints. Geometric and material cross-sectional properties of blades (Stiffness-Matrix and Mass-Matrix) are calculated by using VABS programs on a CATIA model. Natural frequencies and natural modes of the rotating (and non-rotating) blades are obtained by using DYMORE. Fan-Plots which show the variation of the natural frequencies for different modes (Lead-Lag, Flapping, Feathering, etc.) vs. rotor RPM are presented.

  11. Validation of Comprehensive Helicopter Aeroelastic Analysis with Experimental Data

    Directory of Open Access Journals (Sweden)

    Shrinivas R. Bhat


    Full Text Available The experimental data for a Cbladed soft-inplane hingeless main rotor is used to validate a comprehensive aeroelastic analysis. A finite element model has been developed for the rotorblade which predicts rotating frequencies quite well, across a range of rotation speeds. The helicopter is trimmed and the predicted trim-control angles are found to be In the range ofmeasured values for a variety of flight speeds. Power predictions over a range of forward speeds also compare well. Finally, the aeroelastlc analysis is used to study the Importance ofaerodynamic models on the vibration predict~onU. nsteady aerodynamics and free-wake models have been investigated.

  12. Linear decentralized systems with special structure. [for twin lift helicopters (United States)

    Martin, C. F.


    Certain fundamental structures associated with linear systems having internal symmetries are outlined. It is shown that the theory of finite-dimensional algebras and their representations are closely related to such systems. It is also demonstrated that certain problems in the decentralized control of symmetric systems are equivalent to long-standing problems of linear systems theory. Even though the structure imposed arose in considering the problems of twin-lift helicopters, any large system composed of several identical intercoupled control systems can be modeled by a linear system that satisfies the constraints imposed. Internal symmetry can be exploited to yield new system-theoretic invariants and a better understanding of the way in which the underlying structure affects overall system performance.

  13. Dynamic Stability Analysis for Helicopter Rotor/Fuselage Coupled Nonlinear Systems%直升机旋翼/机体耦合非线性系统的动稳定性分析

    Institute of Scientific and Technical Information of China (English)

    胡国才; 向锦武; 张晓谷


    为了准确反映直升机旋翼/机体耦合系统的动稳定性,建立了旋翼/机体耦合非线性动力学微分方程,在时域内求解微分方程得到各片桨叶的挥舞、摆振及机体的响应用以对系统进行数值模拟;为了获得系统稳定性的定量值,用快速傅立叶变换(FFT)确定模态频率,用基于傅立叶级数的移动矩形窗方法得到模态阻尼.地面共振分析表明,时域分析与特征值分析结果具有良好的相关性,并与试验值吻合,从而验证了该方法的有效性.大总距时,用时域分析得到的模态阻尼与试验值吻合得更好,该方法可用于具有非线性减摆器的直升机旋翼/机体耦合系统的动稳定性分析.%In order to accurately predict the dynamic instabilities of a helicopter rotor/fuselage coupled system, nonlinear differential equations are derived and integrated in the time domain to yield responses of rotor blade flapping, lead-lag and fuselage motions to simulate the behavior of the system numerically. To obtain quantitative instabilities, Fast Fourier Transform (FFT) is conducted to estimate the modal frequencies, and Fourier series based moving-block analysis is employed in the predictions of the modal damping in terms of the response time history. Study on the helicopter ground resonance exhibits excellent correlation among the time-domain (TD) analytical results, eigenvalues and wind tunnel test data, thus validating the methodology of the paper. With a large collective pitch set, the predictions of regressive lag modal damping from TD analysis correlate with the experimental data better than from eigen analysis. TD analysis can be applied in the dynamic stability analysis of helicopter rotor/fuselage coupled systems incorporated with nonlinear blade lag dampers.

  14. Design of a Helicopter Stability and Control Augmentation System Using Optimal Control Theory. (United States)

    technique is described for the design of multivariable feedback controllers based upon results in optimal control theory . For a specified performance...helicopter flight envelope. The results show that optimal control theory can be used to design a helicopter stability and control augmentation system

  15. Measures for simulator evaluation of a helicopter obstacle avoidance system (United States)

    Demaio, Joe; Sharkey, Thomas J.; Kennedy, David; Hughes, Micheal; Meade, Perry


    The U.S. Army Aeroflightdynamics Directorate (AFDD) has developed a high-fidelity, full-mission simulation facility for the demonstration and evaluation of advanced helicopter mission equipment. The Crew Station Research and Development Facility (CSRDF) provides the capability to conduct one- or two-crew full-mission simulations in a state-of-the-art helicopter simulator. The CSRDF provides a realistic, full field-of-regard visual environment with simulation of state-of-the-art weapons, sensors, and flight control systems. We are using the CSRDF to evaluate the ability of an obstacle avoidance system (OASYS) to support low altitude flight in cluttered terrain using night vision goggles (NVG). The OASYS uses a laser radar to locate obstacles to safe flight in the aircraft's flight path. A major concern is the detection of wires, which can be difficult to see with NVG, but other obstacles--such as trees, poles or the ground--are also a concern. The OASYS symbology is presented to the pilot on a head-up display mounted on the NVG (NVG-HUD). The NVG-HUD presents head-stabilized symbology to the pilot while allowing him to view the image intensified, out-the-window scene through the HUD. Since interference with viewing through the display is a major concern, OASYS symbology must be designed to present usable obstacle clearance information with a minimum of clutter.

  16. Decision Analysis of Advanced Scout Helicopter Candidates (United States)


    assist the ASH SSG by constructing a comprehensive ASH evaluation model utilizing multi-attribute utility assessment ( MAUA ) modeling. ~~UA is a forre...results are included as well. The output of the MAUA model is a numerical representation of the worth of each ASH candidate. These numbers are...instance of a methodology called Multi-Attribute Utility Analysis ( MAUA ). In general, MAUA is characterized by the represen- tation of outcomes in terms

  17. OH-58 helicopter transmission failure analysis (United States)

    Townsend, D. P.; Coy, J. J.; Hatvani, B. R.


    The OH-58 main transmission gearbox was run at varying output torques, speeds, and oil cooling rates. The gearbox was subsequently run to destruction by draining the oil from the gearbox while operating at a speed of 6200 revs per minute and 36,000 inch-pounds output torque. Primary cause of gearbox failure was overheating and melting of the planet bearing aluminum cages. Complete failure of the gearbox occurred in 28 1/2 minutes after the oil pressure dropped to zero. The alternating and maximum stresses in the gearbox top case were approximately 10 percent of the endurance limit for the material. Deflection of the bevel gear at 67000 inch-pounds output torque indicate a marginal stiffness for the bevel gear supporting system.

  18. Framework of Combined Adaptive and Non-adaptive Attitude Control System for a Helicopter Experimental System

    Institute of Scientific and Technical Information of China (English)

    Akira Inoue; Ming-Cong Deng


    This paper presents a framework of a combined adaptive and non-adaptive attitude control system for a helicopter experimental system. The design method is based on a combination of adaptive nonlinear control and non-adaptive nonlinear control. With regard to detailed attitude control system design, two schemes are shown for different application cases.

  19. Integrated Flight Path Planning System and Flight Control System for Unmanned Helicopters

    Directory of Open Access Journals (Sweden)

    Yu-Hsiang Lin


    Full Text Available This paper focuses on the design of an integrated navigation and guidance system for unmanned helicopters. The integrated navigation system comprises two systems: the Flight Path Planning System (FPPS and the Flight Control System (FCS. The FPPS finds the shortest flight path by the A-Star (A* algorithm in an adaptive manner for different flight conditions, and the FPPS can add a forbidden zone to stop the unmanned helicopter from crossing over into dangerous areas. In this paper, the FPPS computation time is reduced by the multi-resolution scheme, and the flight path quality is improved by the path smoothing methods. Meanwhile, the FCS includes the fuzzy inference systems (FISs based on the fuzzy logic. By using expert knowledge and experience to train the FIS, the controller can operate the unmanned helicopter without dynamic models. The integrated system of the FPPS and the FCS is aimed at providing navigation and guidance to the mission destination and it is implemented by coupling the flight simulation software, X-Plane, and the computing software, MATLAB. Simulations are performed and shown in real time three-dimensional animations. Finally, the integrated system is demonstrated to work successfully in controlling the unmanned helicopter to operate in various terrains of a digital elevation model (DEM.

  20. A parametric analysis of visual approaches for helicopters (United States)

    Moen, G. C.; Dicarlo, D. J.; Yenni, K. R.


    A flight investigation was conducted to determine the characteristic shapes of the altitude, ground speed, and deceleration profiles of visual approaches for helicopters. Two hundred thirty-six visual approaches were flown from nine sets of initial conditions with four types of helicopters. Mathematical relationships were developed that describe the characteristic visual deceleration profiles. These mathematical relationships were expanded to develop equations which define the corresponding nominal ground speed, pitch attitude, pitch rate, and pitch acceleration profiles. Results are applicable to improved helicopter handling qualities in terminal area operations.

  1. Time domain System Identification of Longitudinal Dynamics of Single Rotor Model Helicopter using SIDPAC

    Directory of Open Access Journals (Sweden)

    Arbab Nighat Khizer


    Full Text Available This paper presents a time-domain approach for identification of longitudinal dynamics of single rotor model helicopter. A frequency sweep excitation input signal is applied for hover flying mode widely used for space state linearized model. A fully automated programmed flight test method provides high quality flight data for system identification using the computer controlled flight simulator X-plane©. The flight test data were recorded, analyzed and reduced using the SIDPAC (System Identification Programs for Air Craft toolbox for MATLAB, resulting in an aerodynamic model of single rotor helicopter. Finally, the identified model of single rotor helicopter is validated on Raptor 30-class model helicopter at hover showing the reliability of proposed approach

  2. Maximizing commonality between military and general aviation fly-by-light helicopter system designs (United States)

    Enns, Russell; Mossman, David C.


    In the face of shrinking defense budgets, survival of the United States rotorcraft industry is becoming increasingly dependent on increased sales in a highly competitive civil helicopter market. As a result, only the most competitive rotorcraft manufacturers are likely to survive. A key ingredient in improving our competitive position is the ability to produce more versatile, high performance, high quality, and low cost of ownership helicopters. Fiber optic technology offers a path of achieving these objectives. Also, adopting common components and architectures for different helicopter models (while maintaining each models' uniqueness) will further decrease design and production costs. Funds saved (or generated) by exploiting this commonality can be applied to R&D used to further improve the product. In this paper, we define a fiber optics based avionics architecture which provides the pilot a fly-by-light / digital flight control system which can be implemented in both civilian and military helicopters. We then discuss the advantages of such an architecture.

  3. Maximum acceptable inherent buoyancy limit for aircrew/passenger helicopter immersion suit systems. (United States)

    Brooks, C J


    Helicopter crew and passengers flying over cold water wear immersion suits to provide hypothermic protection in case of ditching in cold water. The suits and linings have trapped air in the material to provide the necessary insulation and are thus very buoyant. By paradox, this buoyancy may be too much for a survivor to overcome in escaping from the cabin of a rapidly sinking inverted helicopter. The Canadian General Standard Board requested that research be conducted to investigate what should be the maximum inherent buoyancy in an immersion suit that would not inhibit escape, yet would provide adequate thermal insulation. This experiment reports on 12 subjects who safely escaped with 146N (33 lbf) of added buoyancy from a helicopter underwater escape trainer. It discusses the logic for and recommendation that the inherent buoyancy in a helicopter crew/passenger immersion suit system should not exceed this figure.

  4. Helicopter emergency medical services accident rates in different international air rescue systems

    Directory of Open Access Journals (Sweden)

    J Hinkelbein


    Full Text Available J Hinkelbein1,2, M Schwalbe2, H V Genzwuerker2,31Department for Anesthesiology and Intensive Care Medicine, University Hospital Cologne, Germany; 2Working Group “Emergency Medicine and Air Rescue”, German Society of Aviation and Space Medicine (DGRLM eV; 3Clinic of Anesthesiology and Intensive Care Medicine, Neckar-Odenwald-Kliniken gGmbH, Hospitals Buchen and Mosbach, Buchen, GermanyAim: Each year approximately two to four helicopter emergency medical services (HEMS crashes occur in Germany. The aim of the present study was to compare crash rates and fatal crash rates in Germany to rates in other countries.Materials and methods: A MEDLINE search from 1970 to 2009 was performed using combinations of the keywords “HEMS”, “rescue helicopter”, “accident”, “accident rate”, “crash”, and “crash rate”. The search was supplemented by additional published data. Data were compared on the basis of 10,000 missions and 100,000 helicopter flying hours. These data were allocated to specific time frames for analyis.Results: Eleven relevant studies were identified. Five studies (three from Germany, one from the US, one from Australia analyzing HEMS accidents on the basis of 10,000 missions were identified. Crash rates per 10,000 missions ranged between 0.4 and 3.05 and fatal crash rates between 0.04 and 2.12. In addition, nine studies (six from the US, two from Germany, one from Australia used 100,000 flying hours as a denominator. Here, crash rates ranged between 1.7 and 13.4 and fatal crash rates between 0.91 and 4.7.Conclusions: Data and accident rates were inhomogeneous and differed significantly. Data analysis was impeded by publication of mean data, use of different time frames, and differences in HEMS systems.Keywords: fatal accident rate, rescue helicopter, fatal crash rate, helicopter emergency medical system, accident analysis

  5. Calculation of rotor impedance for use in design analysis of helicopter airframe vibrations (United States)

    Nygren, Kip P.


    Excessive vibration is one of the most prevalent technical obstacles encountered in the development of new rotorcraft. The inability to predict these vibrations is primarily due to deficiencies in analysis and simulation tools. The Langley Rotorcraft Structural Dynamics Program was instituted in 1984 to meet long term industry needs in the area of rotorcraft vibration prediction. As a part of the Langley program, this research endeavors to develop an efficient means of coupling the rotor to the airframe for preliminary design analysis of helicopter airframe vibrations. The main effort was to modify the existing computer program for modeling the dynamic and aerodynamic behavior of rotorcraft called DYSCO (DYnamic System COupler) to calculate the rotor impedance. DYSCO was recently developed for the U.S. Army and has proven to be adaptable for the inclusion of new solution methods. The solution procedure developed to use DYSCO for the calculation of rotor impedance is presented. Verification of the procedure by comparison with a known solution for a simple wind turbine model is about 75 percent completed, and initial results are encouraging. After the wind turbine impedance is confirmed, the verification effort will continue by comparison to solutions of a more sophisticated rotorcraft model. Future work includes determination of the sensitivity of the rotorcraft airframe vibrations to helicopter flight conditions and rotor modeling assumptions. When completed, this research will ascertain the feasibility and efficiency of the impedance matching method of rotor-airframe coupling for use in the analysis of airframe vibrations during the preliminary rotorcraft design process.

  6. On the vibro-acoustical operational modal analysis of a helicopter cabin (United States)

    Pierro, E.; Mucchi, E.; Soria, L.; Vecchio, A.


    This paper aims to present a modal decomposition formulation for a vibro-acoustical operational modal analysis (OMA). In literature many works can be found on this topic, but until now no attention has been focused on the analytical form of the cross-power spectra (CPs) between the system outputs when a fluid-structure coupling is present. In this work it is shown that the CPs modal decomposition depends on the choice of the references, i.e. acoustical or structural. At first it is theoretically pointed out that the CP formulation for the acoustical and structural case is formally identical if appropriately pre-processed. Then, this theoretical result is verified through the results of an extensive experimental testing on the helicopter EUROCOPTER EC-135. The CPs between the structural output velocities and the acoustical response of the microphone inside the helicopter cabin are considered as inputs of an OMA. In order to verify the effectiveness of the modal model so obtained a classical modal analysis is also performed. The acoustical reference choice reveals to be suitable for a vibro-acoustical OMA. It is highlighted, indeed, that the acoustical pressure measurement inside the enclosure can be used as reference instead of the commonly used structural sensors, both from the theoretical and practical point of view. This is useful for high scale structures where the structural responses are usually measured by means of moving sensor arrays and additional fixed reference sensors should be positioned on the surface.

  7. Resilience and brittleness in the offshore helicopter transportation system: The identification of constraints and sacrifice decisions in pilots' work

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Jose O. [Graduate Program in Informatics-NCE and IM, Federal University of Rio de Janeiro, Cidade Universitaria, Ilha do Fundao, Rio de Janeiro, RJ (Brazil); Woods, David D. [Ohio State University, Ohio (United States); Carvalho, Paulo V.R. [National Nuclear Energy Commission/Nuclear Engineering Institute, Cidade Universitaria-Ilha do Fundao, Rio de Janeiro RJ 21945-970 (Brazil)], E-mail:; Huber, Gilbert J.; Borges, Marcos R.S. [Graduate Program in Informatics-NCE and IM, Federal University of Rio de Janeiro, Cidade Universitaria, Ilha do Fundao, Rio de Janeiro, RJ (Brazil)


    Offshore transportation using helicopters is a complex socio-technical system. The resilience of this system is an emergent property related to performance variability in many nested levels, e.g. pilot activities, maintenance, management systems, helicopter design and so forth. This paper examines production/safety tradeoffs in pilots' work in the helicopter transportation system for the Campos Basin oil fields in Brazil to understand the resilience and brittleness of this system. The study team carried out and analyzed 63 h of interviews with pilots, co-pilots, managers and human resources personnel of some of the main helicopter-operating companies. About 80% of the oil extracted in Brazil comes from this Basin, a 3 h drive north of Rio de Janeiro city. The oil company hires nine helicopter-operating companies to transport about 40,000 people who work on ships and platforms every month. The main goal of this project is to discover how the transport system is resilient and brittle, given the workload demands and economic pressures. The analysis uncovered goal conflicts that arise at the boundaries of the organizations and how people in different roles cope with these conflicts, and their implications to overall system safety and resilience.

  8. Piloted simulator investigation of helicopter control systems effects on handling qualities during instrument flight (United States)

    Forrest, R. D.; Chen, R. T. N.; Gerdes, R. M.; Alderete, T. S.; Gee, D. R.


    An exploratory piloted simulation was conducted to investigate the effects of the characteristics of helicopter flight control systems on instrument flight handling qualities. This joint FAA/NASA study was motivated by the need to improve instrument flight capability. A near-term objective is to assist in updating the airworthiness criteria for helicopter instrument flight. The experiment consisted of variations of single-rotor helicopter types and levels of stability and control augmentation systems (SCAS). These configurations were evaluated during an omnirange approach task under visual and instrument flight conditions. The levels of SCAS design included a simple rate damping system, collective decoupling plus rate damping, and an attitude command system with collective decoupling. A limited evaluation of stick force versus airspeed stability was accomplished. Some problems were experienced with control system mechanization which had a detrimental effect on longitudinal stability. Pilot ratings, pilot commentary, and performance data related to the task are presented.

  9. The NASA/Industry Design Analysis Methods for Vibrations (DAMVIBS) Program - Boeing helicopters airframe finite element modeling (United States)

    Gabel, R.; Lang, P.; Reed, D.


    Finite-element modeling of the airframe vibration of the Army/Boeing CH-47D helicopter is conducted with comparisons to experimental data in an effort to improve the design process. A NASTRAN FEM is developed that is fully representative of the test configuration and includes the support fixture, shakers, and the aircraft/shaker suspension system. The analysis is conducted with specific attention given to the prediction of reasonable forced amplitudes throughout the airframe. Reasonable correlation is noted between the FEM and experimental results, although improved correlation can be obtained by including more accurate damping values and secondary effects such as stringer shear loading. It is shown that the general stress model does not provide an adequate dynamic analysis on which to base design improvements. A more detailed model is required that emphasizes highly detailed helicopter elements and employs a finer mesh particularly in the description of the mass distribution.

  10. A helicopter flight does not induce significant changes in systemic biomarker profiles. (United States)

    Kåsin, Jan Ivar; Kjekshus, John; Aukrust, Pål; Mollnes, Tom Eirik; Wagstaff, Anthony


    Whole-body vibration and noise are inherent characteristics of helicopter operations. The helicopter pilot is affected by vibration from both low-frequency noise and mechanical vibration sources. The way this energy is transmitted to different tissues and organs depends on intensity, frequency and resonance phenomena within the body. Whole-body vibration is known to affect the muscular and skeletal system in the lower part of the spine, but less is known about the response at the cellular level to this stimulation. In some studies, chronic pathological changes have been described in different types of tissue in people exposed to low-frequency noise and vibration. The aim of the present study was to investigate possible cellular reactions to acute exposure to low-frequency noise and vibration in a helicopter. Thirteen healthy males aged 38 (18-69) years were subjected to a 3.5 h helicopter flight in a Westland Sea King Rescue helicopter. Blood tests taken before and after the flight were analysed for more than 40 parameters, including acute phase reactants, markers of leucocyte and platelet activation, complement and hemostasis markers, as well as a broad panel of cytokines, chemokines, growth factors and cell adhesion molecules. The subjects served as their own controls. With the exception of an increase in vascular cell adhesion molecule-1 (VCAM-1) during the flight, no statistically significant changes in the biomarkers were found after controlling for diurnal variation in the control blood tests, which were observed independently of the helicopter flight. In conclusion, one helicopter flight does not induce measurable changes in systemic biomarkers.

  11. Presidential Helicopter Acquisition: Program Established Knowledge-Based Business Case and Entered System Development with Plans for Managing Challenges (United States)


    Presidential Helicopter Acquisition: Program Established Knowledge-Based Business Case and Entered System Development with Plans for Managing Challenges ...Acquisition Reform Act of 2009 (WSARA), This report discusses the cost, schedule, and performance status of the program, challenges it will face in...Presidential Helicopter Acquisition: Program Established Knowledge-Based Business Case and Entered System Development with Plans for Managing

  12. Sliding Mode Implementation of an Attitude Command Flight Control System for a Helicopter in Hover

    Directory of Open Access Journals (Sweden)

    D. J. McGeoch


    Full Text Available This paper presents an investigation into the design of a flight control system, using a decoupled non-linear sliding mode control structure, designed using a linearised, 9th order representation of the dynamics of a PUMA helicopter in hover. The controllers are then tested upon a higher order, non-linear helicopter model, called RASCAL. This design approach is used for attitude command flight control implementation and the control performance is assessed in the terms of handling qualities through the Aeronautical Design Standards for Rotorcraft (ADS-33. In this context a linearised approximation of the helicopter system is used to design an SMC control scheme. These controllers have been found to yield a system that satisfies the Level 1 handling qualities set out by ADS-33. 


    Institute of Scientific and Technical Information of China (English)

    ZHURong-gang; JIANGChangsheng; FENGBin


    A discussion is devoted to the design of an adaptive flight control system of the armed helicopter using wavelet neural network method. Firstly, the control loop of the attitude angle is designed with a dynamic inversion scheme in a quick loop and a slow loop. respectively. Then, in order to compensate the error caused by dynamic inversion, the adaptive flight control system of the armed helicopter using wavelet neural network method is put forward, so the BP wavelet neural network and the Lyapunov stable wavelet neural network are used to design the helicopter flight control system. Finally, the typical maneuver flight is simulated to demonstrate its validity and effectiveness. Result proves that the wavelet neural network has an engineering practical value and the effect of WNN is good.

  14. Impact of a physician-staffed helicopter on a regional trauma system

    DEFF Research Database (Denmark)

    Hesselfeldt, R; Steinmetz, J; Jans, H


    This study aims to compare the trauma system before and after implementing a physician-staffed helicopter emergency medical service (PS-HEMS). Our hypothesis was that PS-HEMS would reduce time from injury to definitive care for severely injured patients.......This study aims to compare the trauma system before and after implementing a physician-staffed helicopter emergency medical service (PS-HEMS). Our hypothesis was that PS-HEMS would reduce time from injury to definitive care for severely injured patients....

  15. Simulation and Analysis of Crashworthiness of Fuel Tank for Helicopters

    Institute of Scientific and Technical Information of China (English)


    Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.

  16. Modelling and Daisy Chaining Control Allocation of a Multirotor Helicopter with a Single Tilting Rotor

    Directory of Open Access Journals (Sweden)

    Robert Porter


    Full Text Available This paper presents the development and implementation of a single tilting rotor multirotor helicopter. A single tilting rotor multirotor helicopter is proposed that allows for decoupled lateral acceleration and attitude states. A dynamics model of the proposed multirotor helicopter is established to enable control system development. A control system architecture and daisy chaining-based control allocation scheme is developed and implemented. The control architecture facilitates the control of decoupled lateral accelerations and attitudes. Further, a computational and experimental analysis is undertaken and offers evidence that the proposed multirotor helicopter and control system architecture enables the multirotor helicopter to achieve lateral accelerations without requiring attitude actuation.

  17. Development of an Autonomous Flight Control System for Small Size Unmanned Helicopter Based on Dynamical Model

    Institute of Scientific and Technical Information of China (English)


    It is devoted to the development of an autonomous flight control system for small size unmanned helicopter based on dynamical model. At first, the mathematical model of a small size helicopter is described. After that simple but effective MTCV control algorithm was proposed. The whole flight control algorithm is composed of two parts:orientation controller based on the model for rotation dynamics and a robust position controller for a double integrator. The MTCV block is also used to achieve translation velocity control. To demonstrate the performance of the presented algorithm, simulation results and results achieved in real flight experiments were presented.

  18. Regressive Analysis on Leaf Nitrogen Content and Near Infrared Reflectance and Its Application for Agricultural Farm Monitoring with Helicopter Mounted Near Infrared Camera

    Directory of Open Access Journals (Sweden)

    Kohei Arai


    Full Text Available Method for evaluation of nitrogen richness of tealeaves with near infrared reflectance is proposed. Also tea farm monitoring with helicopter mounted near infrared camera is proposed. Through experiments and regressive analysis, it is found that the proposed method and monitoring system is validated.

  19. Velocity-Aided Attitude Estimation for Helicopter Aircraft Using Microelectromechanical System Inertial-Measurement Units

    Directory of Open Access Journals (Sweden)

    Sang Cheol Lee


    Full Text Available This paper presents an algorithm for velocity-aided attitude estimation for helicopter aircraft using a microelectromechanical system inertial-measurement unit. In general, high- performance gyroscopes are used for estimating the attitude of a helicopter, but this type of sensor is very expensive. When designing a cost-effective attitude system, attitude can be estimated by fusing a low cost accelerometer and a gyro, but the disadvantage of this method is its relatively low accuracy. The accelerometer output includes a component that occurs primarily as the aircraft turns, as well as the gravitational acceleration. When estimating attitude, the accelerometer measurement terms other than gravitational ones can be considered as disturbances. Therefore, errors increase in accordance with the flight dynamics. The proposed algorithm is designed for using velocity as an aid for high accuracy at low cost. It effectively eliminates the disturbances of accelerometer measurements using the airspeed. The algorithm was verified using helicopter experimental data. The algorithm performance was confirmed through a comparison with an attitude estimate obtained from an attitude heading reference system based on a high accuracy optic gyro, which was employed as core attitude equipment in the helicopter.

  20. Prospects for Eulerian CFD analysis of helicopter vortex flows (United States)

    Drela, Mark; Murman, Earll M.


    The applicability of current finite-volume CFD algorithms based on the Euler equations to the vortex flow over a helicopter in forward flight is investigated analytically. The general characteristics of the flow are reviewed; existing Euler, Navier-Stokes, perturbation, high-order, and adaptive methods are briefly characterized; and a novel Eulerian/Lagrangian approach with entropy and vorticity corrections is presented in detail. Numerical results for simple convection of a finite-core Lamb vortex moving downstream with its axis perpendicular to the flow are presented in graphs, and the possibility of extending the method to three-dimensional, viscous, and shock flows is discussed.

  1. Development of a resonant trailing-edge flap actuation system for helicopter rotor vibration control (United States)

    Kim, J.-S.; Wang, K. W.; Smith, E. C.


    A resonant trailing-edge flap actuation system for helicopter rotors is developed and evaluated experimentally. The concept involves deflecting each individual trailing-edge flap using a compact resonant piezoelectric actuation system. Each resonant actuation system yields high authority, while operating at a single frequency. By tailoring the natural frequencies of the actuation system (including the piezoelectric actuator and the related mechanical and electrical elements) to the required operating frequencies, one can increase the output authority. The robustness of the device can be enhanced by increasing the high authority bandwidth through electric circuitry design. Such a resonant actuation system (RAS) is analyzed for a full-scale piezoelectric induced-shear tube actuator, and bench-top testing is conducted to validate the concept. An adaptive feed-forward controller is developed to realize the electric network dynamics and adapt to phase variation. The control strategy is then implemented via a digital signal processor (DSP) system. Analysis is also performed to examine the rotor system dynamics in forward flight with piezoelectric resonant actuators, using a perturbation method to evaluate the system's time-varying characteristics. Numerical simulations reveal that the resonant actuator concept can be applied to forward flights as well as to hover conditions.


    Directory of Open Access Journals (Sweden)


    Full Text Available This article is aimed at finding the causes of controllability variations of a helicopter while transporting sling load.The maximum angular acceleration taken by the helicopter at similar controller displacement at different flight speeds was taken as a quantity characteristic of controllability efficiency to study the load impact on the helicopter cont- rollability.This article offers research results obtained with the use of the НеliСargо software. This software has proven to be a great tool for integrated research of the impact of an underslung load on the parameters of a helicopter controllability, and allows carrying out an analysis of the impact of an underslung load on the parameters of controllability under its dyna- mic behavior.The performed computational experiments have shown that the helicopter maximum angular acceleration with an underslung load significantly rises, as compared to a helicopter without cargo or a helicopter carrying the same load inside the cargo compartment. The data obtained during computational experiments corresponds to the results of analytical computations, and is in line with the literature based on the experience of helicopter flight operations.The cause of the variation in the helicopter controllability parameters during transportation of an underslung load has been found, that is - the underslung load considerably increases the main rotor thrust, due to sling load, as compared to a helicopter without cargo. When compared to a helicopter carrying a load inside the cargo compartment, this increased efficiency is mainly attributed to the fact that a helicopter with an underslung load has lower rotational inertia, since the load is not inside the cargo compartment, but outside.The obtained results can be used to improve flight manuals and flight personnel training publications, which could play a significant part in ensuring flight safety and security, and increasing the operational efficiency of

  3. A New Framework For Helicopter Vibration Suppression; Time-Periodic System Identification and Controller Design (United States)

    Ulker, Fatma Demet

    In forward flight, helicopter rotor blades function within a highly complex aerodynamic environment that includes both near-blade and far-blade aerodynamic phenomena. These aerodynamic phenomena cause fluctuating aerodynamic loads on the rotor blades. These loads when coupled with the dynamic characteristics and elastic motion of the blade create excessive amount of vibration. These vibrations degrade helicopter performance, passenger comfort and contributes to high cost maintenance problems. In an effort to suppress helicopter vibration, recent studies have developed active control strategies using active pitch links, flaps, twist actuation and higher harmonic control of the swash plate. In active helicopter vibration control, designing a controller in a computationally efficient way requires accurate reduced-order models of complex helicopter aeroelasticity. In previous studies, controllers were designed using aeroelastic models that were obtained by coupling independently reduced aerodynamic and structural dynamic models. Unfortunately, these controllers could not satisfy stability and performance criteria when implemented in high-fidelity computer simulations or real-time experiments. In this thesis, we present a novel approach that provides accurate time-periodic reduced-order models and time-periodic H2 and H infinity controllers that satisfy the stability and performance criteria. Computational efficiency and the necessity of using the approach were validated by implementing an actively controlled flap strategy. In this proposed approach, the reduced-order models were directly identified from high-fidelity coupled aeroelastic analysis by using the time-periodic subspace identification method. Time-periodic H2 and Hinfinity controllers that update the control actuation at every time step were designed. The control synthesis problem was solved using Linear Matrix Inequality and periodic Riccati Equation based formulations, for which an in-house periodic

  4. Analysis of patients with decompression illness transported via physician-staffed emergency helicopters

    Directory of Open Access Journals (Sweden)

    Yasumasa Oode


    Full Text Available Context: There have been few reports investigating the effects of air transportation on patients with decompression illness (DCI. Aims: To investigate the influence of air transportation on patients with DCI transported via physician-staffed emergency helicopters (HEMS: Emergency medical system of physician-staffed emergency helicopters. Settings and Design: A retrospective medical chart review in a single hospital. Materials and Methods: A medical chart review was retrospectively performed in all patients with DCI transported via HEMS between July 2009 and June 2013. The exclusion criteria included cardiopulmonary arrest on surfacing. Statistical analysis used: The paired Student′s t-test. Results: A total of 28 patients were treated as subjects. Male and middle-aged subjects were predominant. The number of patients who suddenly surfaced was 15/28. All patients underwent oxygen therapy during flight, and all but one patient received the administration of lactate Ringer fluid. The subjective symptoms of eight of 28 subjects improved after the flight. The range of all flights under 300 m above sea level. There were no significant differences between the values obtained before and after the flight for Glasgow coma scale, blood pressure, and heart rate. Concerning the SpO 2 , statistically significant improvements were noted after the flight (96.2 ± 0.9% versus 97.3 ± 0.7%. There were no relationships between an improvement in subjective symptoms and the SpO 2 . Conclusion: Improvements in the subjective symptoms and/or SpO 2 of patients with DCI may be observed when the patient is transported via HEMS under flights less than 300 m in height with the administration of oxygen and fluids.

  5. 33 CFR 149.419 - Can the water supply for the helicopter deck fire protection system be part of a fire water system? (United States)


    ... helicopter deck fire protection system be part of a fire water system? 149.419 Section 149.419 Navigation and... § 149.421 may be part of: (1) The fire water system, installed in accordance with Mineral Management... § 149.419 Can the water supply for the helicopter deck fire protection system be part of a fire...

  6. A New Hybrid Control Scheme for an Integrated Helicopter and Engine System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Haibo; WANG Jiankang; CHEN Guoqiang; YAN Changkai


    A new hybrid control scheme is presented with a robust multiple model fusion control (RMMFC) law for a UH-60 helicopter and an active disturbance rejection control (ADRC) controller for its engines.This scheme is a control design method with every subsystem designed separately but fully considering the couplings between them.With three subspaces with respect to forward flight velocity,a RMMFC is proposed to devise a four-loop reference signal tracing control for the helicopter,which escapes the closed-loop system from unstable state due to the extreme complexity of this integrated nonlinear system.The engines are controlled by the proposed ADRC decoupling controller,which fully takes advantage of a good compensation ability for unmodeled dynamics and extra disturbances,so as to compensate torque disturbance in power turbine speed loop.By simulating a forward acceleration flight task,the RMMFC for the helicopter is validated.It is apparent that the integrated helicopter and engine system (IHES) has much better dynamic performance under the new control scheme.Especially in the switching process,the large transient is significantly weakened,and smooth transition among candidate controllers is achieved.Over the entire simulation task,the droop of power turbine speed with the proposed ADRC controller is significantly slighter than with the conventional PID controller,and the response time of the former is much faster than the latter.By simulating a rapid climb and descent flight task,the results also show the feasibility for the application of the proposed multiple model fusion control.Although there is aggressive power demand in this maneuver,the droop of power turbine speed with an ADRC controller is smaller than using a PID controller.The control performance for helicopter and engine is enhanced by adopting this hybrid control scheme,and simulation results in other envelope stale give proofs of robustness for this new scheme.

  7. Stress analysis of advanced attack helicopter composite main rotor blade root end lug (United States)

    Baker, D. J.


    Stress analysis of the Advanced Attack Helicopter (AAH) composite main rotor blade root end lug is described. The stress concentration factor determined from a finite element analysis is compared to an empirical value used in the lug design. The analysis and test data indicate that the stress concentration is primarily a function of configuration and independent of the range of material properties typical of Kevlar-49/epoxy and glass epoxy.

  8. Snow measurement system for airborne snow surveys (GPR system from helicopter) in high mountian areas. (United States)

    Sorteberg, Hilleborg K.


    In the hydropower industry, it is important to have precise information about snow deposits at all times, to allow for effective planning and optimal use of the water. In Norway, it is common to measure snow density using a manual method, i.e. the depth and weight of the snow is measured. In recent years, radar measurements have been taken from snowmobiles; however, few energy supply companies use this method operatively - it has mostly been used in connection with research projects. Agder Energi is the first Norwegian power producer in using radar tecnology from helicopter in monitoring mountain snow levels. Measurement accuracy is crucial when obtaining input data for snow reservoir estimates. Radar screening by helicopter makes remote areas more easily accessible and provides larger quantities of data than traditional ground level measurement methods. In order to draw up a snow survey system, it is assumed as a basis that the snow distribution is influenced by vegetation, climate and topography. In order to take these factors into consideration, a snow survey system for fields in high mountain areas has been designed in which the data collection is carried out by following the lines of a grid system. The lines of this grid system is placed in order to effectively capture the distribution of elevation, x-coordinates, y-coordinates, aspect, slope and curvature in the field. Variation in climatic conditions are also captured better when using a grid, and dominant weather patterns will largely be captured in this measurement system.

  9. Application of the Baseline Rotonet system to the prediction of helicopter tone noise (United States)

    Golub, R. A.; Weir, D. S.; Tracy, M. B.


    The capabilities of the baseline Rotonet system designed to predict helicopter noise are analyzed. The modules of the system utilized for main and tail rotor geometry and blade section aerodynamic characteristics, for analyses, and for source-to-observer geometry, and atmospheric and ground effects calculations are described; a diagram of the system is provided. The Rotonet system produces axial force, tone noise, and sound pressure level information and a one third octave spectrum related to rotor tone noise and broadband noise sources. Main rotor noise predictions are compared with flight data. It is observed that both sets of data reveal increase loading on the advancing side and decrease loading on the retreating side. The tone noise and sound pressure levels for the first and second harmonics correlate well with the flight data; however, there is only fair agreement for the third harmonics of the sound pressure level. Analysis of the spectra display lower noise levels for higher altitudes and lower speeds. It is noted that the baseline Rotonet system is applicable for predicting performance and noise signatures for the lower harmonics. A phase II Rotonet system for evaluating higher harmonics is being developed.

  10. Analiza niskofrekventnog spektra vibracija na elementima strukture helikoptera 'Gazela' / Analysis of low frequency vibrations on the structural connection elements of the Gazelle helicopter

    Directory of Open Access Journals (Sweden)

    Miroslav M. Jovanović


    Full Text Available U radu je prikazan postupak i metodologija ispitivanja vibracija na helikopteru 'gazela' radi definisanja efikasnosti prigušenja vibracija na vezi struktura - sedište pilota. Posebna pažnja posvećena je teorijskim osnovama vibracija na helikopteru, određivanju radnih frekvencija, definisanju režima rada i profila leta helikoptera u toku ispitivanja. Na kraju rada prikazani su rezultati merenja vibracija u frekventnom domenu. / In this paper the procedure and methodology of vibration testing on a Gazelle helicopter are presented with the aim to define efficiency of vibration damping at the structure-pilot seat connection. A particular attention is paid to the theoretical basis of helicopter vibrations, definition of working frequency, regime and profile of flight during the test. The results of the vibration measurement are shown in the frequency domain. Introduction Nowadays, possibility of defining loads and vibrations is one of the most important requests in the design and modification of processes on helicopters. The loads occuring on the main rotor during flight are the basic source of vibrations on the helicopter. Possibilities to satisfy international standards in the area of structural and human vibrations are based on continuous and adequate measurement and analysis of the vibration levels on all elements of helicopters. This paper shows the procedures of vibration measuring and analyzing in order to define efficiency of vibration damping using a modern acquisition system NetdB 12 and its software dBFA Suite. Theoretical analysis of vibration sources on the helicopter main rotor The helicopter rotor operates in a complex aerodynamic flow field. The aerodynamic loads on the rotor blade vary considerably as it moves around the rotor disc, and in steady flight these loads are periodic. A particular attention is paid to a theoretical basis of vibration sources on a helicopter. A complex aerodynamic field in the plane of the helicopter

  11. Comparison of helicopter and ground emergency medical service: a retrospective analysis of a German rescue helicopter base. (United States)

    Mommsen, Philipp; Bradt, Nikolas; Zeckey, Christian; Andruszkow, Hagen; Petri, Max; Frink, Michael; Hildebrand, Frank; Krettek, Christian; Probst, Christian


    In consideration of rising cost pressure in the German health care system, the usefulness of helicopter emergency medical service (HEMS) in terms of time- and cost-effectiveness is controversially discussed. The aim of the present study was to investigate whether HEMS is associated with significantly decreased arrival and transportation times compared to ground EMS. In a retrospective study, we evaluated 1,548 primary emergency missions for time sensitive diagnoses (multiple trauma, traumatic brain and burn injury, heart-attack, stroke, and pediatric emergency) performed by a German HEMS using the medical database, NADIN, of the German Air Rescue Service. Arrival and transportation times were compared to calculated ground EMS times. HEMS showed significantly reduced arrival times at the scene in case of heart-attack, stroke and pediatric emergencies. In contrast, HEMS and ground EMS showed comparable arrival times in patients with multiple trauma, traumatic brain and burn injury due to an increased flight distance. HEMS showed a significantly decreased transportation time to the closest centre capable of specialist care in all diagnosis groups (pambulance services with significantly decreased transportation times.

  12. System Research Of Multi-Barrel Machine Guns Installed On Board Of The Helicopter Of Mi-17 Type

    Directory of Open Access Journals (Sweden)

    Bęczkowski Grzegorz


    Full Text Available This article presents tests of a multi-barreled machine gun system built on board of a helicopter. The described weapon system consists of three 7.62 mm M-134G multi-barreled machine guns built on the designed frames of shooting positions located in the escape hatch window, the side doors and the rear doors of the transport cabin of the Mi-17-1V helicopter.

  13. Computational aspects of helicopter trim analysis and damping levels from Floquet theory (United States)

    Gaonkar, Gopal H.; Achar, N. S.


    Helicopter trim settings of periodic initial state and control inputs are investigated for convergence of Newton iteration in computing the settings sequentially and in parallel. The trim analysis uses a shooting method and a weak version of two temporal finite element methods with displacement formulation and with mixed formulation of displacements and momenta. These three methods broadly represent two main approaches of trim analysis: adaptation of initial-value and finite element boundary-value codes to periodic boundary conditions, particularly for unstable and marginally stable systems. In each method, both the sequential and in-parallel schemes are used and the resulting nonlinear algebraic equations are solved by damped Newton iteration with an optimally selected damping parameter. The impact of damped Newton iteration, including earlier-observed divergence problems in trim analysis, is demonstrated by the maximum condition number of the Jacobian matrices of the iterative scheme and by virtual elimination of divergence. The advantages of the in-parallel scheme over the conventional sequential scheme are also demonstrated.

  14. The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: McDonnell-Douglas Helicopter Company achievements (United States)

    Toossi, Mostafa; Weisenburger, Richard; Hashemi-Kia, Mostafa


    This paper presents a summary of some of the work performed by McDonnell Douglas Helicopter Company under NASA Langley-sponsored rotorcraft structural dynamics program known as DAMVIBS (Design Analysis Methods for VIBrationS). A set of guidelines which is applicable to dynamic modeling, analysis, testing, and correlation of both helicopter airframes and a large variety of structural finite element models is presented. Utilization of these guidelines and the key features of their applications to vibration modeling of helicopter airframes are discussed. Correlation studies with the test data, together with the development and applications of a set of efficient finite element model checkout procedures, are demonstrated on a large helicopter airframe finite element model. Finally, the lessons learned and the benefits resulting from this program are summarized.

  15. Small unmanned helicopter's attitude controller by an on-line adaptive fuzzy control system

    Institute of Scientific and Technical Information of China (English)

    GAO Tong-yue; RAO Jin-jun; GONG Zhen-bang; LUO Jun


    Since small unmanned helicopter flight attitude control process has strong time-varying characteristics and there are random disturbances, the conventional control methods with unchanged parameters are often unworkable. An on-line adaptive fuzzy control system (AFCS) was designed, in a way that does not depend on a process model of the plant or its approximation in the form of a Jacobian matrix. Neither is it necessary to know the desired response at each instant of time. AFCS implement a simultaneous on-line tuning of fuzzy rules and output scale of fuzzy control system. The two cascade controller design with an inner (attitude controller) and outer controller (navigation controller) of the small unmanned helicopter was proposed. At last, an attitude controller based on AFCS was implemented. The flight experiment showed that the proposed fuzzy logic controller provides quicker response, smaller overshoot, higher precision, robustness and adaptive ability. It satisfies the needs of autonomous flight.

  16. Design of a Stability Augmentation System for an Unmanned Helicopter Based on Adaptive Control Techniques

    Directory of Open Access Journals (Sweden)

    Shouzhao Sheng


    Full Text Available The task of control of unmanned helicopters is rather complicated in the presence of parametric uncertainties and measurement noises. This paper presents an adaptive model feedback control algorithm for an unmanned helicopter stability augmentation system. The proposed algorithm can achieve a guaranteed model reference tracking performance and speed up the convergence rates of adjustable parameters, even when the plant parameters vary rapidly. Moreover, the model feedback strategy in the algorithm further contributes to the improvement in the control quality of the stability augmentation system in the case of low signal to noise ratios, mainly because the model feedback path is noise free. The effectiveness and superiority of the proposed algorithm are demonstrated through a series of tests.

  17. Development and evaluation of a helicopter-borne water-quality monitoring system (United States)

    Wallace, J. W.; Jordan, R. A.; Flynn, J.; Thomas, R. W.


    A small, helicopter-borne water-quality monitoring package is being developed by the NASA/EPA using a combination of basic in situ water quality sensors and physical sample collector technology. The package is a lightweight system which can be carried and operated by one person as a passenger in a small helicopter typically available by rental at commercial airports. Real-time measurements are made by suspending the water quality monitoring package with a cable from the hovering helicopter. Designed primarily for use in rapidly assessing hazardous material spills in inland and coastal zone water bodies, the system can survey as many as 20 data stations up to 1.5 kilometers apart in 1 hour. The system provides several channels of sensor data and allows for the addition of future sensors. The system will also collect samples from selected sites with sample collection on command. An EPA Spill Response Team member can easily transport, deploy, and operate the water quality monitoring package to determine the distribution, movement, and concentration of the spilled material in the water body.

  18. A rotor-mounted digital instrumentation system for helicopter blade flight research measurements (United States)

    Knight, V. H., Jr.; Haywood, W. S., Jr.; Williams, M. L.


    A rotor mounted flight instrumentation system developed for helicopter rotor blade research is described. The system utilizes high speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested on an AH-1G helicopter. The system employs microelectronic pulse code modulation (PCM) multiplexer digitizer stations located remotely on the blade and in a hub mounted metal canister. As many as 25 sensors can be remotely digitized by a 2.5 mm thick electronics package mounted on the blade near the tip to reduce blade wiring. The electronics contained in the canister digitizes up to 16 sensors, formats these data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data are transmitted over an RF link to the ground for real time monitoring and to the helicopter fuselage for tape recording. The complete system is powered by batteries located in the canister and requires no slip rings on the rotor shaft.

  19. Light Helicopter Family Trade-Off Analysis. Volume 10. Appendices V, W, X, and Z (United States)


    night vision goggles 12. Inadequacies of skid gear 13. Mast bumping 14 Unknown Total Number of Accidents (percent of total) 39...TOA Cost TOD Aircraft Development LHX Helicopter Investment Baseline R&D Estimate LCC Force Disk Commonality Load LCCE Vision Damage Field...programable keyboard US Army Missile Command modification work order nap of the earth nonrecurrirg costs night vision pilotage system one engine

  20. Chaotic Artificial Bee Colony Algorithm for System Identification of a Small-Scale Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Li Ding


    Full Text Available The purpose of this paper is devoted to developing a chaotic artificial bee colony algorithm (CABC for the system identification of a small-scale unmanned helicopter state-space model in hover condition. In order to avoid the premature of traditional artificial bee colony algorithm (ABC, which is stuck in local optimum and can not reach the global optimum, a novel chaotic operator with the characteristics of ergodicity and irregularity was introduced to enhance its performance. With input-output data collected from actual flight experiments, the identification results showed the superiority of CABC over the ABC and the genetic algorithm (GA. Simulations are presented to demonstrate the effectiveness of our proposed algorithm and the accuracy of the identified helicopter model.

  1. Design, fabrication and testing of two electrohydraulic vibration isolation systems for helicopter environments (United States)

    Allen, R. E.; Calcaterra, P. C.


    Two electrohydraulic vibration isolation systems were designed and fabricated to reduce the vertical vibrations transmitted to the XH-51N research helicopter cabin at the blade passage frequency (18 Hz) and its first harmonic (36 Hz). Hydraulic power and electrical control are provided to two separate servoactuators from a common power supply and control electronics package located behind the pilot's seat. One servoactuator is installed between the cabin and fuselage and replaces an existing passive spring. A second servoactuator is mounted between the existing seat and cabin floor. Both servoactuators incorporate a mechanical failsafe design. The control electronics circuitry provides automatic tracking of the blade passage frequency. Results of laboratory, environmental and ground vibration tests employing an XH-51A stripped down helicopter fuselage show that the active cabin isolator reduces the vertical vibrations transmitted from the fuselage attachment point to the cabin attachment point at 18 and 36 Hz (or as an alternative, 6 Hz) by better than 90 percent.

  2. Controllability Analysis for Multirotor Helicopter Rotor Degradation and Failure (United States)

    Du, Guang-Xun; Quan, Quan; Yang, Binxian; Cai, Kai-Yuan


    This paper considers the controllability analysis problem for a class of multirotor systems subject to rotor failure/wear. It is shown that classical controllability theories of linear systems are not sufficient to test the controllability of the considered multirotors. Owing to this, an easy-to-use measurement index is introduced to assess the available control authority. Based on it, a new necessary and sufficient condition for the controllability of multirotors is derived. Furthermore, a controllability test procedure is approached. The proposed controllability test method is applied to a class of hexacopters with different rotor configurations and different rotor efficiency parameters to show its effectiveness. The analysis results show that hexacopters with different rotor configurations have different fault-tolerant capabilities. It is therefore necessary to test the controllability of the multirotors before any fault-tolerant control strategies are employed.

  3. An Examination of Safety Management Systems and Aviation Technologies in the Helicopter Emergency Medical Services Industry (United States)

    Buckner, Steven A.

    The Helicopter Emergency Medical Service (HEMS) industry has a significant role in the transportation of injured patients, but has experienced more accidents than all other segments of the aviation industry combined. With the objective of addressing this discrepancy, this study assesses the effect of safety management systems implementation and aviation technologies utilization on the reduction of HEMS accident rates. Participating were 147 pilots from Federal Aviation Regulations Part 135 HEMS operators, who completed a survey questionnaire based on the Safety Culture and Safety Management System Survey (SCSMSS). The study assessed the predictor value of SMS implementation and aviation technologies to the frequency of HEMS accident rates with correlation and multiple linear regression. The correlation analysis identified three significant positive relationships. HEMS years of experience had a high significant positive relationship with accident rate (r=.90; pNVG) (r=.38; pNVG, TAWS, and SMS, HEMS years of experience explained 81.4% of the variance in accident rate scores (p<.05), and HEMS years of experience was found to be a significant predictor of accident rates (p<.05). Additional quantitative regression analysis was recommended to replicate the results of this study and to consider the influence of these variables for continued reduction of HEMS accidents, and to induce execution of SMS and aviation technologies from a systems engineering application. Recommendations for practice included the adoption of existing regulatory guidance for a SMS program. A qualitative analysis was also recommended for future study SMS implementation and HEMS accident rate from the pilot's perspective. A quantitative longitudinal study would further explore inferential relationships between the study variables. Current strategies should include the increased utilization of available aviation technology resources as this proactive stance may be beneficial for the establishment of

  4. Vertical Drop Testing and Analysis of the WASP Helicopter Skid Gear (United States)

    Fuchs, Yvonne T.; Jackson, Karen E.


    Human occupant modeling and injury risk assessment have been identified as areas of research for improved prediction of rotorcraft crashworthiness within the NASA Aeronautics Program s Subsonic Rotary Wing Project. As part of this effort, an experimental program was conducted to assess the impact performance of a skid gear for use on the WASP kit-built helicopter, which is marketed by HeloWerks, Inc. of Hampton, Virginia. Test data from a drop test at an impact velocity of 8.4 feet-per-second were used to assess a finite element model of the skid gear test article. This assessment included human occupant analytic models developed for execution in LS-DYNA. The test article consisted of an aluminum skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Aerospace Anthropomorphic Test Devices (ATDs) were seated on the platform and secured using a four-point restraint system. The goal of the test-analysis correlation is to further the understanding of LS-DYNA ATD occupant models and responses in the vertical (or spinal) direction. By correlating human occupant experimental test data for a purely vertical impact with the LS-DYNA occupant responses, improved confidence in the use of these tools and better understanding of the limitations of the automotive-based occupant models for aerospace application can begin to be developed.

  5. FLIR, NVG and HMS/D systems for helicopter operation: Review (United States)

    Boehm, H. D. V.


    In the last decade, electro-optical systems have been used successfully in military and civil applications. They extend the scope of operation of ground vehicles, helicopters and fixed wing aircraft from daytime into nighttime, with a 24 hour readiness covering even bad weather conditions. The visual aids fall into two physical categories: the image intensifiers, which amplify reflected residual light in the near infrared and the thermal imager, which detect the thermal radiation of all bodies mainly in the 8 to 12 micrometer atmospheric window for bodies with T approx. 20 C. During the last five years, the investigator has carried out helicopter flight trials at night using examples of all these visionic aids (FLIR, LLLTV, NVG, HMS/D and Direct View Optics) for piloting and observation tasks. The detection, recognition and identification range of nine different FLIR were tested in ground and laboratory tests. The evaluation of an optical sensor platform location in the helicopter nose-, roof- and mast-mounted versions, the comparison of thermal and intensifier images and the NVG compatible cockpit were topics of the tests. The optical sensors are described with their limitations and some results of the trials are given, with regard to the pilot's stress situation and eye safety.

  6. The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program : Bell Helicopter Textron accomplishments (United States)

    Cronkhite, James D.


    Accurate vibration prediction for helicopter airframes is needed to 'fly from the drawing board' without costly development testing to solve vibration problems. The principal analytical tool for vibration prediction within the U.S. helicopter industry is the NASTRAN finite element analysis. Under the NASA DAMVIBS research program, Bell conducted NASTRAN modeling, ground vibration testing, and correlations of both metallic (AH-1G) and composite (ACAP) airframes. The objectives of the program were to assess NASTRAN airframe vibration correlations, to investigate contributors to poor agreement, and to improve modeling techniques. In the past, there has been low confidence in higher frequency vibration prediction for helicopters that have multibladed rotors (three or more blades) with predominant excitation frequencies typically above 15 Hz. Bell's findings under the DAMVIBS program, discussed in this paper, included the following: (1) accuracy of finite element models (FEM) for composite and metallic airframes generally were found to be comparable; (2) more detail is needed in the FEM to improve higher frequency prediction; (3) secondary structure not normally included in the FEM can provide significant stiffening; (4) damping can significantly affect phase response at higher frequencies; and (5) future work is needed in the areas of determination of rotor-induced vibratory loads and optimization.

  7. Robust 1D inversion and analysis of helicopter electromagnetic (HEM) data

    DEFF Research Database (Denmark)

    Tølbøll, R.J.; Christensen, N.B.


    Ground-based electrical and electromagnetic methods are used systematically for quantitative hydrogeologic investigations in Denmark. In recent years, a desire for faster and more cost-efficient methods has led to growing interest in the possibility of using airborne systems, and in 2001 a number...... of test flights were performed using a frequency-domain, helicopter-borne electromagnetic (HEM) system. We perform a theoretical examination of the resolution capabilities of the applied system. Quantitative model parameter analyses show that the system only weakly resolves conductive, near-surface layers...

  8. Analytical investigation of the pericyclic variable-speed transmission system for helicopter main-gearbox (United States)

    Saribay, Zihni Burcay

    and load carrying capacity of the PVT face-gears are analyzed at the helicopter torque levels. The dynamic motion of the nutating gear mechanisms is studied to capture the load carrying capacity of the PVT support bearings. A design analysis of the PVT system with 24:1 reduction ratio at 764HP power level is conducted to replace 3 reduction stages of the existing K-MAX intermeshing rotor transmission system. The design and analysis tools established in this research are applied in the design study. The achieved design is compared to the existing K-MAX transmission. Approximately 50% weight reduction and 70% volume reduction are accomplished with the PVT system with less than 1% lower efficiency than existing K-MAX drive train gears.

  9. Flight Parameter Display System For The Mi-17 Helicopter – Test Results

    Directory of Open Access Journals (Sweden)

    Bęczkowski Grzegorz


    Full Text Available This article presents flight tests of a newly developed Helmet-Mounted Flight Parameters Display System (SWPL. Presented system is designed to illustrate full piloting and navigational information, warning about emergency on the helicopter’s board and signaling on-board helicopter systems failures on the translucent display. The system is designed to work in day and night time conditions. In night time conditions, the system cooperates with night vision goggles applicable in Polish Air Force. The article presents the main components of the tested system, along with their purpose and function. It also describes in detail the methods of display implemented in the system and the amount of displayed information. The article discusses the required range and the actual course of the flight tests of that system. Tests were conducted on a Mi-17-1V helicopter. The results of the flight tests of the Helmet-Mounted Display System are given in conclusion, in particular regarding meeting the tactical and technical requirements of the system.

  10. Performance and Vibration Analyses of Lift-Offset Helicopters

    Directory of Open Access Journals (Sweden)

    Jeong-In Go


    Full Text Available A validation study on the performance and vibration analyses of the XH-59A compound helicopter is conducted to establish techniques for the comprehensive analysis of lift-offset compound helicopters. This study considers the XH-59A lift-offset compound helicopter using a rigid coaxial rotor system as a verification model. CAMRAD II (Comprehensive Analytical Method of Rotorcraft Aerodynamics and Dynamics II, a comprehensive analysis code, is used as a tool for the performance, vibration, and loads analyses. A general free wake model, which is a more sophisticated wake model than other wake models, is used to obtain good results for the comprehensive analysis. Performance analyses of the XH-59A helicopter with and without auxiliary propulsion are conducted in various flight conditions. In addition, vibration analyses of the XH-59A compound helicopter configuration are conducted in the forward flight condition. The present comprehensive analysis results are in good agreement with the flight test and previous analyses. Therefore, techniques for the comprehensive analysis of lift-offset compound helicopters are appropriately established. Furthermore, the rotor lifts are calculated for the XH-59A lift-offset compound helicopter in the forward flight condition to investigate the airloads characteristics of the ABC™ (Advancing Blade Concept rotor.

  11. Autonomous Hovering Flight of a Small Helicopter (United States)

    Ohkura, Akihiro; Tokutake, Hiroshi; Sunada, Shigeru

    During the 20th century, aircraft were only used for transportation. If aircraft can be made small and lightweight, however, they can become tools to assist in everyday life. We developed a small, lightweight co-axial helicopter with a rotor diameter of about 30cm. The mechanisms for varying cyclic pitch of the upper and lower rotors, which are used in the coaxial helicopter for entertainment, are adopted in our develop helicopter. Our developed helicopter is equipped with a flight control system for the attitude and position, which is composed of a micro computer and some sensors. And the helicopter can make autonomous hovering flight just measuring the height and the distances from the walls. The weight of the helicopter is no more than 200g and this helicopter is the lightest helicopter for an autonomous hovering flight among the helicopters where all control systems are onboard, as far as the authors know.

  12. Type-2 fuzzy logic control of a 2-DOF helicopter (TRMS system) (United States)

    Zeghlache, Samir; Kara, Kamel; Saigaa, Djamel


    The helicopter dynamic includes nonlinearities, parametric uncertainties and is subject to unknown external disturbances. Such complicated dynamics involve designing sophisticated control algorithms that can deal with these difficulties. In this paper, a type 2 fuzzy logic PID controller is proposed for TRMS (twin rotor mimo system) control problem. Using triangular membership functions and based on a human operator experience, two controllers are designed to control the position of the yaw and the pitch angles of the TRMS. Simulation results are given to illustrate the effectiveness of the proposed control scheme.

  13. Does helicopter transport improve outcomes independently of emergency medical system time? (United States)

    Ryb, Gabriel E; Dischinger, Patricia; Cooper, Carnell; Kufera, Joseph A


    Helicopter emergency medical systems (HEMS) have been reported to improve trauma survival. This study seeks to determine HEMS effect on survival across different subpopulations in relation to injury severity, degree of physiologic derangement, and transportation time (TT). The 2007 National Trauma Data Bank adult patients transported directly to hospitals by ground ambulance or HEMS were compared in relation to their survival with discharge and other possible confounders. Multivariate models were constructed to determine the adjusted odds ratios (OR) of survival for the entire cohort and across subpopulations stratified by different Injury Severity Score (ISS), hospital Revised Trauma Score (RTS), and TT. A total of 192,422 patients with complete data were analyzed. HEMS patients (15.3%) experienced lower survival rates than those transported by ground (93.8% vs. 96.1%, p < 0.001). Multivariate analysis revealed a survival advantage for HEMS in the entire cohort (OR, 1.78 [1.65-1.92]). Adding TT to the model did not affect HEMS effect on survival. HEMS effect was present across all ISS levels but was limited to those with RTS of less than 6 (n = 15,427; OR, 2.28 [2.10-2.49]). In contrast, those with RTS of 6 or greater experienced lower adjusted survival when transported by HEMS (n = 176,995; OR, 0.83 [0.74-0.94]). Stratification by RTS and ISS did not affect the results. Substratification by TT revealed no effect of HEMS on survival among patients with RTS of less than 6, ISS of less than 16, and TT of 60 minutes or greater. Remaining associations were not affected by TT substratification. HEMS beneficial effect on survival seems to be limited to patients with physiologic instability. Physiologically stable patients seem to have a worse outcome when transported by air. Epidemiologic/prognostic study, level III.

  14. Flight evaluation of a computer aided low-altitude helicopter flight guidance system (United States)

    Swenson, Harry N.; Jones, Raymond D.; Clark, Raymond


    The Flight Systems Development branch of the U.S. Army's Avionics Research and Development Activity (AVRADA) and NASA Ames Research Center have developed for flight testing a Computer Aided Low-Altitude Helicopter Flight (CALAHF) guidance system. The system includes a trajectory-generation algorithm which uses dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and precision navigation information to determine a trajectory between mission way points that seeks valleys to minimize threat exposure. This system was developed and evaluated through extensive use of piloted simulation and has demonstrated a 'pilot centered' concept of automated and integrated navigation and terrain mission planning flight guidance. This system has shown a significant improvement in pilot situational awareness, and mission effectiveness as well as a decrease in training and proficiency time required for a near terrain, nighttime, adverse weather system. AVRADA's NUH-60A STAR (Systems Testbed for Avionics Research) helicopter was specially modified, in house, for the flight evaluation of the CALAHF system. The near terrain trajectory generation algorithm runs on a multiprocessor flight computer. Global Positioning System (GPS) data are integrated with Inertial Navigation Unit (INU) data in the flight computer to provide a precise navigation solution. The near-terrain trajectory and the aircraft state information are passed to a Silicon Graphics computer to provide the graphical 'pilot centered' guidance, presented on a Honeywell Integrated Helmet And Display Sighting System (IHADSS). The system design, piloted simulation, and initial flight test results are presented.

  15. Results of Short-Period Helicopter System Identification Using Output-Error and Hybrid Search-Gradient Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Ronaldo Vieira Cruz


    Full Text Available This article focuses on the problem of parameter estimation of the uncoupled, linear, short-period aerodynamic derivatives of a “Twin Squirrel” helicopter in level flight and constant speed. A flight test campaign is described with respect to maneuver specification, flight test instrumentation, and experimental data collection used to estimate the aerodynamic derivatives. The identification problem is solved in the time domain using the output-error approach, with a combination of Genetic Algorithm (GA and Levenberg-Marquardt optimization algorithms. The advantages of this hybrid GA and gradient-search methodology in helicopter system identification are discussed.

  16. LS-DYNA Analysis of a Full-Scale Helicopter Crash Test (United States)

    Annett, Martin S.


    A full-scale crash test of an MD-500 helicopter was conducted in December 2009 at NASA Langley's Landing and Impact Research facility (LandIR). The MD-500 helicopter was fitted with a composite honeycomb Deployable Energy Absorber (DEA) and tested under vertical and horizontal impact velocities of 26 ft/sec and 40 ft/sec, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of a system integrated LS-DYNA finite element model. In preparation for the full-scale crash test, a series of sub-scale and MD-500 mass simulator tests was conducted to evaluate the impact performances of various components, including a new crush tube and the DEA blocks. Parameters defined within the system integrated finite element model were determined from these tests. The objective of this paper is to summarize the finite element models developed and analyses performed, beginning with pre-test and continuing through post test validation.

  17. Modeling, State Estimation and Control of Unmanned Helicopters (United States)

    Lau, Tak Kit

    Unmanned helicopters hold both tremendous potential and challenges. Without risking the lives of human pilots, these vehicles exhibit agile movement and the ability to hover and hence open up a wide range of applications in the hazardous situations. Sparing human lives, however, comes at a stiff price for technology. Some of the key difficulties that arise in these challenges are: (i) There are unexplained cross-coupled responses between the control axes on the hingeless helicopters that have puzzled researchers for years. (ii) Most, if not all, navigation on the unmanned helicopters relies on Global Navigation Satellite Systems (GNSSs), which are susceptible to jamming. (iii) It is often necessary to accommodate the re-configurations of the payload or the actuators on the helicopters by repeatedly tuning an autopilot, and that requires intensive human supervision and/or system identification. For the dynamics modeling and analysis, we present a comprehensive review on the helicopter actuation and dynamics, and contributes toward a more complete understanding on the on-axis and off-axis dynamical responses on the helicopter. We focus on a commonly used modeling technique, namely the phase-lag treatment, and employ a first-principles modeling method to justify that (i) why that phase-lag technique is inaccurate, (ii) how we can analyze the helicopter actuation and dynamics more accurately. Moreover, these dynamics modeling and analysis reveal the hard-to-measure but crucial parameters on a helicopter model that require the constant identifications, and hence convey the reasoning of seeking a model-implicit method to solve the state estimation and control problems on the unmanned helicopters. For the state estimation, we present a robust localization method for the unmanned helicopter against the GNSS outage. This method infers position from the acceleration measurement from an inertial measurement unit (IMU). In the core of our method are techniques of the sensor

  18. Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system (United States)

    Haas, Christian; Lobach, John; Hendricks, Stefan; Rabenstein, Lasse; Pfaffling, Andreas


    Sea ice is an important climate variable and is also an obstacle for marine operations in polar regions. We have developed a small and lightweight, digitally operated frequency-domain electromagnetic-induction (EM) system, a so-called EM bird, dedicated for measurements of sea ice thickness. It is 3.5 m long and weighs only 105 kg, and can therefore easily be shipped to remote places and operated from icebreakers and small helicopters. Here, we describe the technical design of the bird operating at two frequencies of f1 = 3.68 kHz and f2 = 112 kHz, and study its technical performance. On average, noise amounts to ± 8.5 ppm and ± 17.5 ppm for f1 and f2, respectively. Electrical drift amounts to 200 ppm/h and 2000 ppm/h for f1 and f2, during the first 0.5 h of operation. It is reduced by 75% after 2 h. Calibration of the Inphase and Quadrature ppm signals varies by 2 to 3%. A sensitivity study shows that all these signal variations do affect the accuracy of the ice thickness retrieval, but that it remains better than ± 0.1 m over level ice in most cases. This accuracy is also confirmed by means of comparisons of the helicopter EM data with other thickness measurements. The paper also presents the ice thickness retrieval from single-component Inphase data of f1.

  19. Face-gear drives: Design, analysis, and testing for helicopter transmission applications (United States)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.


    The use of face-gears in helicopter transmissions was explored. A light-weight, split-torque transmission design utilizing face-gears is described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, grinding, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. An analytical study showed that the face-gear drive is relatively insensitive to gear misalignment with respect to transmission errors, but the tooth contact is affected by misalignment. A method of localizing the bearing contact to permit operation with misalignment was explored. Two new methods for grinding of the face-gear tooth surfaces were also investigated. The proper choice of shaft stiffness enabled good load sharing in the split-torque transmission design. Face-gear experimental studies were also conducted. These tests demonstrated the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions.

  20. Face-gear drives: Design, analysis, and testing for helicopter transmission applications (United States)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.


    The use of face-gears in helicopter transmissions was explored. A light-weight, split-torque transmission design utilizing face-gears is described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, grinding, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. An analytical study showed that the face-gear drive is relatively insensitive to gear misalignment with respect to transmission errors, but the tooth contact is affected by misalignment. A method of localizing the bearing contact to permit operation with misalignment was explored. Two new methods for grinding of the face-gear tooth surfaces were also investigated. The proper choice of shaft stiffness enabled good load sharing in the split-torque transmission design. Face-gear experimental studies were also conducted. These tests demonstrated the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions.

  1. Analysis of In-Flight Vibration Measurements from Helicopter Transmissions (United States)

    Mosher, Marianne; Huff, Ed; Barszcz


    In-flight vibration measurements from the transmission of an OH-58C KIOWA are analyzed. In order to understand the effect of normal flight variation on signal shape, the first gear mesh components of the planetary gear system and bevel gear are studied in detail. Systematic patterns occur in the amplitude and phase of these signal components with implications for making time synchronous averages and interpreting gear metrics in flight. The phase of the signal component increases as the torque increases; limits on the torque range included in a time synchronous average may now be selected to correspond to phase change limits on the underlying signal. For some sensors and components, an increase in phase variation and/or abrupt change in the slope of the phase dependence on torque are observed in regions of very low amplitude of the signal component. A physical mechanism for this deviation is postulated. Time synchronous averages should not be constructed in torque regions with wide phase variation.

  2. Aeromechanical stability analysis of a multirotor vehicle with application to hybrid heavy lift helicopter dynamics (United States)

    Venkatesan, C.; Friedmann, P. P.


    The Hybrid Heavy Lift Helicopter (HHLH) is a potential candidate vehicle aimed at providing heavy lift capability at low cost. This vehicle consists of a buoyant envelope attached to a supporting structure. Four rotor systems are also attached to the supporting structure. Nonlinear equations of motion capable of modeling the dynamics of this multi-rotor/support frame/vehicle system have been developed and used to study the fundamental aeromechanical stability characteristics of this class of vehicles. The mechanism of coupling between the blades, supporting structure and rigid body modes is identified and the effect of buoyancy ratio (buoyant lift/total weight) on the vehicle dynamics is studied. It is shown that dynamics effects have a major role in the design of such vehicles. The analytical model developed is also useful for studying the aeromechanical stability of single rotor and tandem rotor coupled rotor/fuselage systems.

  3. Aeromechanical stability analysis of a multirotor vehicle with application to hybrid heavy lift helicopter dynamics (United States)

    Venkatesan, C.; Friedmann, P. P.


    The Hybrid Heavy Lift Helicopter (HHLH) is a potential candidate vehicle aimed at providing heavy lift capability at low cost. This vehicle consists of a buoyant envelope attached to a supporting structure. Four rotor systems are also attached to the supporting structure. Nonlinear equations of motion capable of modeling the dynamics of this multi-rotor/support frame/vehicle system have been developed and used to study the fundamental aeromechanical stability characteristics of this class of vehicles. The mechanism of coupling between the blades, supporting structure and rigid body modes is identified and the effect of buoyancy ratio (buoyant lift/total weight) on the vehicle dynamics is studied. It is shown that dynamics effects have a major role in the design of such vehicles. The analytical model developed is also useful for studying the aeromechanical stability of single rotor and tandem rotor coupled rotor/fuselage systems.

  4. Development of swashplateless helicopter blade pitch control system using the limited angle direct-drive motor (LADDM

    Directory of Open Access Journals (Sweden)

    Wang Jian


    Full Text Available It can be greatly beneficial to remove the swashplate of conventional helicopter, because the swashplate is usually complicated, aerodynamically resistive, and obstacle of more complex pitch control for improving performance. The present technologies for helicopter vibration reduction are usually narrow in effective range or requiring additional actuators and signal transfer links, and more effective technology is desired. Helicopter blade pitch control system, which is removed of swashplate and integrated high-frequency pitch control function for active vibration reduction, is likely the suitable solution at current technical level. Several potential implementation schemes are discussed, such as blades being directly or indirectly driven by actuators mounted in rotating frame and application of different types of actuators, especially implementation schemes of electro-mechanical actuator with or without gear reducer. It is found that swashplateless blade pitch control system based on specially designed limited angle direct-drive motor (LADDM is a more practical implementation scheme. An experimental prototype of the finally selected implementation scheme has been designed, fabricated and tested on rotor tower. The test results show considerable feasibility of the swashplateless helicopter blade pitch control system using the LADDM.

  5. Development of swashplateless helicopter blade pitch control system using the limited angle direct-drive motor (LADDM)

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Wang Haowen; Wu Chao


    It can be greatly beneficial to remove the swashplate of conventional helicopter, because the swashplate is usually complicated, aerodynamically resistive, and obstacle of more complex pitch control for improving performance. The present technologies for helicopter vibration reduc-tion are usually narrow in effective range or requiring additional actuators and signal transfer links, and more effective technology is desired. Helicopter blade pitch control system, which is removed of swashplate and integrated high-frequency pitch control function for active vibration reduction, is likely the suitable solution at current technical level. Several potential implementation schemes are discussed, such as blades being directly or indirectly driven by actuators mounted in rotating frame and application of different types of actuators, especially implementation schemes of electro-mechanical actuator with or without gear reducer. It is found that swashplateless blade pitch control system based on specially designed limited angle direct-drive motor (LADDM) is a more practical implementation scheme. An experimental prototype of the finally selected implementation scheme has been designed, fabricated and tested on rotor tower. The test results show considerable feasibility of the swashplateless helicopter blade pitch control system using the LADDM.

  6. Autonomous landing of a helicopter UAV with a ground-based multisensory fusion system (United States)

    Zhou, Dianle; Zhong, Zhiwei; Zhang, Daibing; Shen, Lincheng; Yan, Chengping


    In this study, this paper focus on the vision-based autonomous helicopter unmanned aerial vehicle (UAV) landing problems. This paper proposed a multisensory fusion to autonomous landing of an UAV. The systems include an infrared camera, an Ultra-wideband radar that measure distance between UAV and Ground-Based system, an PAN-Tilt Unit (PTU). In order to identify all weather UAV targets, we use infrared cameras. To reduce the complexity of the stereovision or one-cameral calculating the target of three-dimensional coordinates, using the ultra-wideband radar distance module provides visual depth information, real-time Image-PTU tracking UAV and calculate the UAV threedimensional coordinates. Compared to the DGPS, the test results show that the paper is effectiveness and robustness.

  7. A real-time blade element helicopter simulation for handling qualities analysis (United States)

    Du Val, Ronald W.


    A simulation model which utilizes parallel processing platforms is described in terms of its contributions to improved real-time helicopter simulation. The FLIGHTLAB parallel processing environment is explained, and the relative advantages of the blade element and rotor map models for rigid and elastic articulated blades are discussed. A UH-60 simulation is conducted by means of a rigid model with 14 degrees of freedom, as well as an elastic model with 26 degrees of freedom, to compare trim conditions, longitudinal static margins, and longitudinal and lateral frequency responses. The FLIGHTLAB system is shown to facilitate restructuring for parallel processing as well as the systematic comparison of a variety of models. The system can facilitate the comparison of rigid and elastic blade element rotor models at NASA-Ames and other research facilities.

  8. Implementation and verification of a comprehensive helicopter coupled rotor - Fuselage analysis (United States)

    Wood, E. R.; Banerjee, D.; Shamie, J.; Straub, F.; Dinyavari, M. A. H.


    The analytical basis and the application of a Rotor/Airframe Comprehensive Aeroelastic Program (RACAP) are described in detail. The rationale behind each analytical choice is outlined and the modular procedure is described. The program is verified by application to the AH-1G helicopter. The applicability of various airload prediction models is examined, and both the steady and vibratory responses of the blade are compared with flight test data. Reasonable correlation is found between measured and calculated blade response, with excellent correlation for vibration amplitudes at various locations on the fuselage such as engine, pilot seat, and gunner. Within the analytical model, comparisons are drawn between an isolated blade analysis and a coupled rotor/fuselage model. The deficiency of the former in the context of the AH-1G is highlighted.

  9. Intelligent electrical harness connector assembly using Bell Helicopter Textron's 'Wire Harness Automated Manufacturing System' (United States)

    Springer, D. W.

    Bell Helicopter Textron, Incorporated (BHTI) installed two Digital Equipment Corporation PDP-11 computers and an American Can Inc. Ink Jet printer in 1980 as the cornerstone of the Wire Harness Automated Manufacturing System (WHAMS). WHAMS is based upon the electrical assembly philosophy of continuous filament harness forming. This installation provided BHTI with a 3 to 1 return-on-investment by reducing wire and cable identification cycle time by 80 percent and harness forming, on dedicated layout tooling, by 40 percent. Yet, this improvement in harness forming created a bottle neck in connector assembly. To remove this bottle neck, BHTI has installed a prototype connector assembly cell that integrates the WHAMS' data base and innovative computer technologies to cut harness connector assembly cycle time. This novel connector assembly cell uses voice recognition, laser identification, and animated computer graphics to help the electrician in the correct assembly of harness connectors.

  10. Development of a vision-based ground target detection and tracking system for a small unmanned helicopter

    Institute of Scientific and Technical Information of China (English)

    LIN Feng; LUM Kai-Yew; CHEN Ben M.; LEE Tong H


    It is undoubted that the latest trend in the unmanned aerial vehicles (UAVs) community is towards visionbased unmanned small-scale helicopter,utilizing the maneuvering capabilities of the helicopter and the rich information of visual sensors,in order to arrive at a versatile platform for a variety of applications such as navigation,surveillance,tracking,etc.In this paper,we present the development of a visionbased ground target detection and tracking system for a small UAV helicopter.More specifically,we propose a real-time vision algorithm,based on moment invariants and two-stage pattern recognition,to achieve automatic ground target detection.In the proposed algorithm,the key geometry features of the target are extracted to detect and identify the target.Simultaneously,a Kalman filter is used to estimate and predict the position of the target,referred to as dynamic features,based on its motion model.These dynamic features are then combined with geometry features to identify the target in the second-stage of pattern recognition,when geometry features of the target change significantly due to noise and disturbance in the environment.Once the target is identified,an automatic control scheme is utilized to control the pan/tilt visual mechanism mounted on the helicopter such that the identified target is to be tracked at the center of the captured images.Experimental results based on images captured by the small-scale unmanned helicopter,SheLion,in actual flight tests demonstrate the effectiveness and robustness of the overall system.

  11. Correlation of finite-element structural dynamic analysis with measured free vibration characteristics for a full-scale helicopter fuselage (United States)

    Kenigsberg, I. J.; Dean, M. W.; Malatino, R.


    The correlation achieved with each program provides the material for a discussion of modeling techniques developed for general application to finite-element dynamic analyses of helicopter airframes. Included are the selection of static and dynamic degrees of freedom, cockpit structural modeling, and the extent of flexible-frame modeling in the transmission support region and in the vicinity of large cut-outs. The sensitivity of predicted results to these modeling assumptions are discussed. Both the Sikorsky Finite-Element Airframe Vibration analysis Program (FRAN/Vibration Analysis) and the NASA Structural Analysis Program (NASTRAN) have been correlated with data taken in full-scale vibration tests of a modified CH-53A helicopter.


    Directory of Open Access Journals (Sweden)

    C. F. Lo


    Full Text Available There are many disasters happened because the weather changes extremely in these years. To facilitate applications such as environment detection or monitoring becomes very important. Therefore, the development of rapid low cost systems for collecting near real-time spatial information is very critical. Rapid spatial information collection has become an emerging trend for remote sensing and mapping applications. This study develops a Direct Georeferencing (DG based Unmanned Aerial Vehicle (UAV helicopter photogrammetric platform where an Inertial Navigation System (INS/Global Navigation Satellite System (GNSS integrated Positioning and Orientation System (POS system is implemented to provide the DG capability of the platform. The performance verification indicates that the proposed platform can capture aerial images successfully. A flight test is performed to verify the positioning accuracy in DG mode without using Ground Control Points (GCP. The preliminary results illustrate that horizontal DG positioning accuracies in the x and y axes are around 5 meter with 100 meter flight height. The positioning accuracy in the z axis is less than 10 meter. Such accuracy is good for near real-time disaster relief. The DG ready function of proposed platform guarantees mapping and positioning capability even in GCP free environments, which is very important for rapid urgent response for disaster relief. Generally speaking, the data processing time for the DG module, including POS solution generalization, interpolation, Exterior Orientation Parameters (EOP generation, and feature point measurements, is less than 1 hour.

  13. Concepts for the design of a completely active helicopter isolation system using output vector feedback (United States)

    Schulz, G.


    The theory of output vector feedback (a few measured quantities) is used to derive completely active oscillation isolation functions for helicopters. These feedback controller concepts are tested with various versions of the BO 105 helicopter and their performance is demonstrated. A compensation of the vibrational excitations from the rotor and harmonics of the number of blades are considered. There is also a fast and automatic trim function for maneuvers.

  14. Multicenter observational prehospital resuscitation on helicopter study. (United States)

    Holcomb, John B; Swartz, Michael D; DeSantis, Stacia M; Greene, Thomas J; Fox, Erin E; Stein, Deborah M; Bulger, Eileen M; Kerby, Jeffrey D; Goodman, Michael; Schreiber, Martin A; Zielinski, Martin D; O'Keeffe, Terence; Inaba, Kenji; Tomasek, Jeffrey S; Podbielski, Jeanette M; Appana, Savitri N; Yi, Misung; Wade, Charles E


    Earlier use of in-hospital plasma, platelets, and red blood cells (RBCs) has improved survival in trauma patients with severe hemorrhage. Retrospective studies have associated improved early survival with prehospital blood product transfusion (PHT). We hypothesized that PHT of plasma and/or RBCs would result in improved survival after injury in patients transported by helicopter. Adult trauma patients transported by helicopter from the scene to nine Level 1 trauma centers were prospectively observed from January to November 2015. Five helicopter systems had plasma and/or RBCs, whereas the other four helicopter systems used only crystalloid resuscitation. All patients meeting predetermined high-risk criteria were analyzed. Patients receiving PHT were compared with patients not receiving PHT. Our primary analysis compared mortality at 3 hours, 24 hours, and 30 days, using logistic regression to adjust for confounders and site heterogeneity to model patients who were matched on propensity scores. Twenty-five thousand one hundred eighteen trauma patients were admitted, 2,341 (9%) were transported by helicopter, of which 1,058 (45%) met the highest-risk criteria. Five hundred eighty-five of 1,058 patients were flown on helicopters carrying blood products. In the systems with blood available, prehospital median systolic blood pressure (125 vs 128) and Glasgow Coma Scale (7 vs 14) was significantly lower, whereas median Injury Severity Score was significantly higher (21 vs 14). Unadjusted mortality was significantly higher in the systems with blood products available, at 3 hours (8.4% vs 3.6%), 24 hours (12.6% vs 8.9%), and 30 days (19.3% vs 13.3%). Twenty-four percent of eligible patients received a PHT. A median of 1 unit of RBCs and plasma were transfused prehospital. Of patients receiving PHT, 24% received only plasma, 7% received only RBCs, and 69% received both. In the propensity score matching analysis (n = 109), PHT was not significantly associated with mortality

  15. Application of a Broadband Active Vibration Control System to a Helicopter Trim Panel (United States)

    Cabell, Randolph H.; Schiller, Noah H.; Simon, Frank


    This paper discusses testing of a broadband active vibration control concept on an interior trim panel in a helicopter cabin mockup located at ONERA's Centre de Toulouse. The control system consisted of twelve diamond-shaped piezoelectric actuators distributed around a 1.2m x 1.2m trim panel. Accelerometers were mounted at the four vertices of each diamond. The aspect ratio of the diamond was based on the dielectric constants of the piezoelectric material in order to create an actuator-sensor pair that was collocated over a broad frequency range. This allowed robust control to be implemented using simple, low power analog electronics. Initial testing on a thick acrylic window demonstrated the capability of the controller, but actuator performance was less satisfactory when mounted on a composite sandwich trim panel. This may have been due to the orthotropic nature of the trim panel, or due to its much higher stiffness relative to the acrylic window. Insights gained from a finite element study of the actuator-sensor-structural system are discussed.

  16. Comparison of Test and Finite Element Analysis for Two Full-Scale Helicopter Crash Tests (United States)

    Annett, Martin S.; Horta,Lucas G.


    Finite element analyses have been performed for two full-scale crash tests of an MD-500 helicopter. The first crash test was conducted to evaluate the performance of a composite deployable energy absorber under combined flight loads. In the second crash test, the energy absorber was removed to establish the baseline loads. The use of an energy absorbing device reduced the impact acceleration levels by a factor of three. Accelerations and kinematic data collected from the crash tests were compared to analytical results. Details of the full-scale crash tests and development of the system-integrated finite element model are briefly described along with direct comparisons of acceleration magnitudes and durations for the first full-scale crash test. Because load levels were significantly different between tests, models developed for the purposes of predicting the overall system response with external energy absorbers were not adequate under more severe conditions seen in the second crash test. Relative error comparisons were inadequate to guide model calibration. A newly developed model calibration approach that includes uncertainty estimation, parameter sensitivity, impact shape orthogonality, and numerical optimization was used for the second full-scale crash test. The calibrated parameter set reduced 2-norm prediction error by 51% but did not improve impact shape orthogonality.

  17. Coupled rotor/fuselage dynamic analysis of the AH-1G helicopter and correlation with flight vibrations data (United States)

    Corrigan, J. C.; Cronkhite, J. D.; Dompka, R. V.; Perry, K. S.; Rogers, J. P.; Sadler, S. G.


    Under a research program designated Design Analysis Methods for VIBrationS (DAMVIBS), existing analytical methods are used for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM), which has been developed, extensively documented, and correlated with ground vibration test. One procedure that was used for predicting coupled rotor-fuselage vibrations using the advanced Rotorcraft Flight Simulation Program C81 and NASTRAN is summarized. Detailed descriptions of the analytical formulation of rotor dynamics equations, fuselage dynamic equations, coupling between the rotor and fuselage, and solutions to the total system of equations in C81 are included. Analytical predictions of hub shears for main rotor harmonics 2p, 4p, and 6p generated by C81 are used in conjunction with 2p OLS measured control loads and a 2p lateral tail rotor gearbox force, representing downwash impingement on the vertical fin, to excite the NASTRAN model. NASTRAN is then used to correlate with measured OLS flight test vibrations. Blade load comparisons predicted by C81 showed good agreement. In general, the fuselage vibration correlations show good agreement between anslysis and test in vibration response through 15 to 20 Hz.

  18. Crack of a helicopter main rotor actuator attachment: failure analysis and lessons learned

    Directory of Open Access Journals (Sweden)

    L. Allegrucci


    Full Text Available A Light Utility Helicopter (LUH, in the course of a training flight, leaving the ground during the taxi to take off, went into an uncontrolled rolling to the right; consequently the helicopter gradually laid down on the right side. The impact with the runway destroyed the rotating blades up to the hubs rotor. The accident investigation focused on main rotor oscillatory plate servo actuators . These components, directly linked to the cloche movements, regulate main rotor blades plane tilt and pitch. Following the preliminary examination, only front servo actuator attachment was found to be broken in two parts. In detail, the present paper deals with the fracture analysis results. The servo actuator attachment material is a 2014 Aluminum alloy extrudate, undergone to T651 heat treatment. Fracture surfaces were examined by optical and electronic microscopy in order to determine the main morphological features and consequently to trace the origin of failure mechanism and causes. The accordance with the specification requirements about alloy composition was verified by quantitative elementary analysis through inductive coupled plasma spectroscopy (ICP; furthermore, semi-quantitative elementary analysis was locally verified by Energy dispersion spectroscopy X ray (EDS_RX. Finally, the hydrogen content of the material was evaluated by the total hydrogen analysis. Microstructural and technological alloy characteristics were verified as well by using metallographic microscopy and hardness testing of the material.Macroscopic fracture surfaces evidences were characterized by the lack of any significant plastic deformations and by the presence of symmetry compared to the servo actuator axis. Microscopic fracture features of both the investigated surfaces were not coherent to the hypothesis of an impact of the main rotor to the soil. Further achieved evidences, such as grain boundary fracture propagation, the presence of corrosion products, were all in

  19. Failure analysis of a bearing in a helicopter turbine engine due to electrical discharge damage

    Directory of Open Access Journals (Sweden)

    Michael K. Budinski


    Full Text Available This article documents the metallurgical evaluation of a rolling element bearing that failed due to electrical discharge damage. This rolling element bearing was used in a helicopter turbine engine that failed in-flight, resulting in a hard landing of the helicopter. Optical and electron microscopy as well as energy dispersive spectroscopy were used to evaluate the bearing. Pitting and material transfer on the external bearing races bearing and mating surfaces revealed that the electrical discharge damage occurred while the engine's components were not rotating.

  20. When is the helicopter faster? A comparison of helicopter and ground ambulance transport times. (United States)

    Diaz, Marco A; Hendey, Gregory W; Bivins, Herbert G


    A retrospective analysis of 7,854 ground ambulance and 1,075 helicopter transports was conducted. The 911-hospital arrival intervals for three transport methods were compared: ground, helicopter dispatched simultaneously with ground unit, and helicopter dispatched nonsimultaneously after ground unit response. Compared with ground transports, simultaneously dispatched helicopter transports had significantly shorter 911-hospital arrival intervals at all distances greater than 10 miles from the hospital. Nonsimultaneously dispatched helicopter transport was significantly faster than ground at distances greater than 45 miles, and simultaneous helicopter dispatch was faster than nonsimultaneous at virtually all distances. Ground transport was significantly faster than either air transport modality at distances less than 10 miles from the hospital. Ground ambulance transport provided the shortest 911-hospital arrival interval at distances less than 10 miles from the hospital. At distances greater than 10 miles, simultaneously dispatched air transport was faster. Nonsimultaneous dispatched helicopter transport was faster than ground if greater than 45 miles from the hospital.

  1. Analysis of U.S. Military Helicopter Operations in Support of Humanitarian Assistance and Disaster Relief (United States)


    49 VI. ALLOCATION OF HELICOPTERS TO ROUTES .............................................51 A. MODEL 2: HEURISTIC APPROACH... Heuristic Distribution.......................................................................................53 Table 16. Priority the villagers needed (JLLIS, 2008d). Aircrew debriefs on safe and acceptable landing zones were critical to the tsunami relief success

  2. Helicopter vibration reduction using robust control


    Mannchen, Thomas


    This dissertation presents a control law for helicopters to reduce vibration and to increase damping using individual blade control. H-infinity control synthesis is used to develop a robust controller usable in different operating conditions with different helicopter flight speeds. The control design is applied in simulation to the four-blade BO 105 helicopter rotor, which is equipped with an individual blade control system, where the pitch rod links are replaced by hydraulic actuators, allow...

  3. Prototype of a tilt rotor helicopter: A helicopter comprising a multi-rotor system with individual collective and cyclic pitch control.


    Napsholm, Svein Rivli


    The use of drones and remote operated aircrafts has become a useful tool for the oil and mining industry, when searching for new production areas. The remote controlled aircrafts can perform some of the tasks during these operations such as deploy sensors, gather geographical data and perform area inspections. The smaller and cheaper aircrafts are a cost and time effective solution compared to using bigger helicopters and air planes. In this master thesis, it is proposed a new type of remote ...

  4. Law of Torsional Vibration and Discussion on Vibration Suppression Based on Helicopter/Engine System (United States)

    Miao, Lizhen; Zhang, Haibo; Ning, Jingtao


    With both the advantages like attacking close targets and the disadvantages especially like dynamic coupling, helicopter deserves more investigations these days. This paper did dynamic study both in a simplified and a multi-degree of freedom, comprehensive helicopter model, so that to reveal the law of torsional vibration. In the simplified model, the law how arbitrary parameter affects the first-order vibration mode, is discussed. Then, the validation is done in a multi-degree of freedom model by means of the fast Fourier transformation (FFT) method. In this case, how the low-frequency vibration mode relates with the first-order vibration mode is clearly presented, as well as the research direction to design a filter. Lastly, a simple filter is designed with some simulations.

  5. Heavy Class Helicopter Fuselage Model Drag Reduction by Active Flow Control Systems (United States)

    De Gregorio, F.


    A comprehensive experimental investigation of helicopter blunt fuselage drag reduction using active flow control is being carried out within the European Clean Sky program. The objective is to demonstrate the capability of several active flow technologies to decrease fuselage drag by alleviating the flow separation occurring in the rear area of some helicopters. The work is performed on a simplified blunt fuselage at model-scale. Two different flow control actuators are considered for evaluation: steady blowing, unsteady blowing (or pulsed jets). Laboratory tests of each individual actuator are first performed to assess their performance and properties. The fuselage model is then equipped with these actuators distributed in 3 slots located on the ramp bottom edge. This paper addresses the promising results obtained during the wind-tunnel campaign, since significant drag reductions are achieved for a wide range of fuselage angles of attack and yaw angles without detriment of the other aerodynamic characteristics.

  6. Study of Helicopter Roll Control Effectiveness Criteria. (United States)


    variety of helicopter configurations and control system types , and a wide range of flight tasks and maneuvers. The basis of the experimental design...represent a wide range of basic helicopter rotor hub and airframe designs and flight control system types . It was intended to generally limit

  7. Helicopter emergency medical services accident rates in different international air rescue systems


    Hinkelbein, J; Schwalbe, M.; H V Genzwuerker


    J Hinkelbein1,2, M Schwalbe2, H V Genzwuerker2,31Department for Anesthesiology and Intensive Care Medicine, University Hospital Cologne, Germany; 2Working Group “Emergency Medicine and Air Rescue”, German Society of Aviation and Space Medicine (DGRLM) eV; 3Clinic of Anesthesiology and Intensive Care Medicine, Neckar-Odenwald-Kliniken gGmbH, Hospitals Buchen and Mosbach, Buchen, GermanyAim: Each year approximately two to four helicopter emergency medical services (HEMS) cra...

  8. The Development of the CONDUIT Advanced Control System Design and Evaluation Interface with a Case Study Application to an Advanced Fly by Wire Helicopter Design (United States)

    Colbourne, Jason


    This report details the development and use of CONDUIT (Control Designer's Unified Interface). CONDUIT is a design tool created at Ames Research Center for the purpose of evaluating and optimizing aircraft control systems against handling qualities. Three detailed design problems addressing the RASCAL UH-60A Black Hawk are included in this report to show the application of CONDUIT to helicopter control system design.

  9. Light Helicopter Family Trade-Off Analysis. Volume 4. Appendix N (United States)


    U) It should be noted that designing a tail pylon folding point into a composite fuselage creates significant structural problema due to...engine operating at this level is 30 minutes. However, after a (short) period of time at a less power setting, V( lRP ) may be used again. The exact...HELICOPTER -so -20 -10 IB +10 +20 ♦ao EFFCCNCYOt) Figure N-VI-25. V( lRP ) speed efficiency sumraary. N-VI-31 LHX


    Institute of Scientific and Technical Information of China (English)

    诸德超; 邓忠民; 王荇卫


    In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This ethod is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free bending as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method is introduced to form a numerical algorithm. Both static and natural vibration problems of sample box beams are analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.

  11. A 3D imaging system for the non-intrusive in-flight measurement of the deformation of an aircraft propeller and a helicopter rotor (United States)

    Stasicki, Bolesław; Boden, Fritz; Ludwikowski, Krzysztof


    The non-intrusive in-flight deformation measurement and the resulting local pitch of an aircraft propeller or helicopter rotor blade is a demanding task. The idea of an imaging system integrated and rotating with the air-craft propeller has already been presented at the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been designed, constructed and tested in the laboratory as well as in-flight on the Cobra VUT100 of Evektor Aerotechnik, Kunovice (CZ). The major aim of the EU FP7 project AIM2 ("Advanced In-flight Measurement techniques 2" - contract No. 266107) was to ascertain the feasibility of this technique under extreme conditions - vibration and large centrifugal forces - to real flight testing. Based on the gained experience a new rotating system for the application on helicopter rotors has recently been constructed and tested on the whirl tower of Airbus Helicopters, Donauwoerth (D). In this paper the principle of the applied Image Pattern Correlation Technique (IPCT), a specialized type of Digital Image Correlation (DIC), is outlined and the construction of both rotating 3D image acquisition systems dedicated to the in-flight deformation measurement of the aircraft propeller and helicopter rotor are described. Furthermore, the results of the ground and in-flight tests of these systems will be shown and discussed. The obtained results will be helpful for manufacturers in the design of their future aircrafts.

  12. Helicopter Field Testing of NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) System fully Integrated with the Morpheus Vertical Test Bed Avionics (United States)

    Epp, Chirold D.; Robertson, Edward A.; Ruthishauser, David K.


    The Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project was chartered to develop and mature to a Technology Readiness Level (TRL) of six an autonomous system combining guidance, navigation and control with real-time terrain sensing and recognition functions for crewed, cargo, and robotic planetary landing vehicles. The ALHAT System must be capable of identifying and avoiding surface hazards to enable a safe and accurate landing to within tens of meters of designated and certified landing sites anywhere on a planetary surface under any lighting conditions. This is accomplished with the core sensing functions of the ALHAT system: Terrain Relative Navigation (TRN), Hazard Detection and Avoidance (HDA), and Hazard Relative Navigation (HRN). The NASA plan for the ALHAT technology is to perform the TRL6 closed loop demonstration on the Morpheus Vertical Test Bed (VTB). The first Morpheus vehicle was lost in August of 2012 during free-flight testing at Kennedy Space Center (KSC), so the decision was made to perform a helicopter test of the integrated ALHAT System with the Morpheus avionics over the ALHAT planetary hazard field at KSC. The KSC helicopter tests included flight profiles approximating planetary approaches, with the entire ALHAT system interfaced with all appropriate Morpheus subsystems and operated in real-time. During these helicopter flights, the ALHAT system imaged the simulated lunar terrain constructed in FY2012 to support ALHAT/Morpheus testing at KSC. To the best of our knowledge, this represents the highest fidelity testing of a system of this kind to date. During this helicopter testing, two new Morpheus landers were under construction at the Johnson Space Center to support the objective of an integrated ALHAT/Morpheus free-flight demonstration. This paper provides an overview of this helicopter flight test activity, including results and lessons learned, and also provides an overview of recent integrated testing of ALHAT on the second

  13. Wind-Tunnel Evaluation of the Effect of Blade Nonstructural Mass Distribution on Helicopter Fixed-System Loads (United States)

    Wilbur, Matthew L.; Yeager, Jr, William T.; Singleton, Jeffrey D.; Mirick, Paul H.; Wilkie, W K.


    This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses.

  14. The helicopter - some ergonomic factors. (United States)

    Lovesey, E J


    Helicopter pilots are some of the hardest working human operators, because of the machine's inherant instability and control problems. This article covers some aspects where ergonomists might help to improve the overall system. After considering basic differences between helicopters and fixed wing aircraft, the author examines controls, where there are prospects of using miniature hand levers; cockpit vision and displays with particular reference to night and instrument flying; seating and vibration where the effects of protective clothing and harnesses are considered; and cabin noise from the engine, transmission and intercom systems. Finally, he assesses pilot activity using cine film techniques for different types of flight.

  15. Output Tracking for Systems with Non-Hyperbolic and Near Non-Hyperbolic Internal Dynamics: Helicopter Hover Control (United States)

    Devasia, Santosh


    A technique to achieve output tracking for nonminimum phase linear systems with non-hyperbolic and near non-hyperbolic internal dynamics is presented. This approach integrates stable inversion techniques, that achieve exact-tracking, with approximation techniques, that modify the internal dynamics to achieve desirable performance. Such modification of the internal dynamics is used (1) to remove non-hyperbolicity which an obstruction to applying stable inversion techniques and (2) to reduce large pre-actuation time needed to apply stable inversion for near non-hyperbolic cases. The method is applied to an example helicopter hover control problem with near non-hyperbolic internal dynamic for illustrating the trade-off between exact tracking and reduction of pre-actuation time.

  16. An Optimized Air-Core Coil Sensor with a Magnetic Flux Compensation Structure Suitable to the Helicopter TEM System

    Directory of Open Access Journals (Sweden)

    Chen Chen


    Full Text Available The air-core coil sensor (ACS is widely used as a transducer to measure the variation in magnetic fields of a helicopter transient electromagnetic (TEM system. A high periodic emitting current induces the magnetic field signal of the underground medium. However, such current also generates a high primary field signal that can affect the received signal of the ACS and even damage the receiver. To increase the dynamic range of the received signal and to protect the receiver when emitting current rises/falls, the combination of ACS with magnetic flux compensation structure (bucking coil is necessary. Moreover, the optimized ACS, which is composed of an air-core coil and a differential pre-amplifier circuit, must be investigated to meet the requirements of the helicopter TEM system suited to rapid surveying for shallow buried metal mine in rough topography. Accordingly, two ACSs are fabricated in this study, and their performance is verified and compared inside a magnetic shielding room. Using the designed ACSs, field experiments are conducted in Baoqing County. The field experimental data show that the primary field response can be compensated when the bucking coil is placed at an appropriate point in the range of allowed shift distance beyond the center of the transmitting coil and that the damage to the receiver induced by the over-statured signal can be solved. In conclusion, a more suitable ACS is adopted and is shown to have better performance, with a mass of 2.5 kg, resultant effective area of 11.6 m2 (i.e., diameter of 0.496 m, 3 dB bandwidth of 66 kHz, signal-to-noise ratio of 4 (i.e., varying magnetic field strength of 0.2 nT/s, and normalized equivalent input noise of 3.62 nV/m2.

  17. A vision system for landing an unmanned helicopter in a complex environment (United States)

    Shi, Haiqing; Wang, Hong


    We present a vision-based landing algorithm for an autonomous helicopter under complex environment (there are several suspected targets). The algorithm is integrated with algorithms for visual acquisition, recognition of the target and computing the navigation information. In our algorithm, we use international standard landing mark as our landing target. The experiment results demonstrate that our algorithm has the feature of robustness, accuracy and real time. It can meet the actual flight requirements well: the average processing time of a 640×480 image is less than 40ms; the position error is below 5cm in each axis of translation; the angle error is below 3.5°. Based on the algorithm, we win the champion of the aerial robot competition in the 2008 China robot competition and the RoboCup China open.

  18. Helicopter Human Factors (United States)

    Hart, Sandra G.; Sridhar, Banavar (Technical Monitor)


    Even under optimal conditions, helicopter flight is a most demanding form of human-machine interaction, imposing continuous manual, visual, communications, and mental demands on pilots. It is made even more challenging by small margins for error created by the close proximity of terrain in NOE flight and missions flown at night and in low visibility. Although technology advances have satisfied some current and proposed requirements, hardware solutions alone are not sufficient to ensure acceptable system performance and pilot workload. However, human factors data needed to improve the design and use of helicopters lag behind advances in sensor, display, and control technology. Thus, it is difficult for designers to consider human capabilities and limitations when making design decisions. This results in costly accidents, design mistakes, unrealistic mission requirements, excessive training costs, and challenge human adaptability. NASA, in collaboration with DOD, industry, and academia, has initiated a program of research to develop scientific data bases and design principles to improve the pilot/vehicle interface, optimize training time and cost, and maintain pilot workload and system performance at an acceptable level. Work performed at Ames, and by other research laboratories, will be reviewed to summarize the most critical helicopter human factors problems and the results of research that has been performed to: (1) Quantify/model pilots use of visual cues for vehicle control; (2) Improve pilots' performance with helmet displays of thermal imagery and night vision goggles for situation awareness and vehicle control; (3) Model the processes by which pilots encode maps and compare them to the visual scene to develop perceptually and cognitively compatible electronic map formats; (4) Evaluate the use of spatially localized auditory displays for geographical orientation, target localization, radio frequency separation; (5) Develop and flight test control

  19. Helicopter Human Factors (United States)

    Hart, Sandra G.; Sridhar, Banavar (Technical Monitor)


    Even under optimal conditions, helicopter flight is a most demanding form of human-machine interaction, imposing continuous manual, visual, communications, and mental demands on pilots. It is made even more challenging by small margins for error created by the close proximity of terrain in NOE flight and missions flown at night and in low visibility. Although technology advances have satisfied some current and proposed requirements, hardware solutions alone are not sufficient to ensure acceptable system performance and pilot workload. However, human factors data needed to improve the design and use of helicopters lag behind advances in sensor, display, and control technology. Thus, it is difficult for designers to consider human capabilities and limitations when making design decisions. This results in costly accidents, design mistakes, unrealistic mission requirements, excessive training costs, and challenge human adaptability. NASA, in collaboration with DOD, industry, and academia, has initiated a program of research to develop scientific data bases and design principles to improve the pilot/vehicle interface, optimize training time and cost, and maintain pilot workload and system performance at an acceptable level. Work performed at Ames, and by other research laboratories, will be reviewed to summarize the most critical helicopter human factors problems and the results of research that has been performed to: (1) Quantify/model pilots use of visual cues for vehicle control; (2) Improve pilots' performance with helmet displays of thermal imagery and night vision goggles for situation awareness and vehicle control; (3) Model the processes by which pilots encode maps and compare them to the visual scene to develop perceptually and cognitively compatible electronic map formats; (4) Evaluate the use of spatially localized auditory displays for geographical orientation, target localization, radio frequency separation; (5) Develop and flight test control

  20. Adaptation of the Neural Network Recognition System of the Helicopter on Its Acoustic Radiation to the Flight Speed

    Directory of Open Access Journals (Sweden)

    V. K. Hohlov


    Full Text Available The article concerns the adaptation of a neural tract that recognizes a helicopter from the aerodynamic and ground objects by its acoustic radiation to the helicopter flight speed. It uses non-centered informative signs-indications of estimating signal spectra, which correspond to the local extremes (maximums and minimums of the power spectrum of input signal and have the greatest information when differentiating the helicopter signals from those of tracked vehicles. The article gives justification to the principle of the neural network (NN adaptation and adaptation block structure, which solves problems of blade passage frequency estimation when capturing the object and track it when tracking a target, as well as forming a signal to control the resonant filter parameters of the selection block of informative signs. To create the discriminatory characteristics of the discriminator are used autoregressive statistical characteristics of the quadrature components of signal, obtained through the discrete Hilbert Converter (DGC that perforMathematical modeling of the tracking meter using the helicopter signals obtained in real conditions is performed. The article gives estimates of the tracking parameter when using a tracking meter with DGC by sequential records of realized acoustic noise of the helicopter. It also shows a block-diagram of the adaptive NN. The scientific novelty of the work is that providing the invariance of used informative sign, the counts of local extremes of power spectral density (PSD to changes in the helicopter flight speed is reached due to adding the NN structure and adaptation block, which is implemented as a meter to track the apparent passage frequency of the helicopter rotor blades using its relationship with a function of the autoregressive acoustic signal of the helicopter.Specialized literature proposes solutions based on the use of training classifiers with different parametric methods of spectral representations

  1. Contributions to the dynamics of helicopters with active rotor controls (United States)

    Malpica, Carlos A.

    This dissertation presents an aeromechanical closed loop stability and response analysis of a hingeless rotor helicopter with a Higher Harmonic Control (HHC) system for vibration reduction. The analysis includes the rigid body dynamics of the helicopter and blade flexibility. The gain matrix is assumed to be fixed and computed off-line. The discrete elements of the HHC control loop are rigorously modeled, including the presence of two different time scales in the loop. By also formulating the coupled rotor-fuselage dynamics in discrete form, the entire coupled helicopter-HHC system could be rigorously modeled as a discrete system. The effect of the periodicity of the equations of motion is rigorously taken into account by converting the system into an equivalent system with constant coefficients and identical stability properties using a time lifting technique. The most important conclusion of the present study is that the discrete elements in the HHC loop must be modeled in any HHC analysis. Not doing so is unconservative. For the helicopter configuration and HHC structure used in this study, an approximate continuous modeling of the HHC system indicates that the closed loop, coupled helicopter-HHC system remains stable for optimal feedback control configurations which the more rigorous discrete analysis shows can result in closed loop instabilities. The HHC gains must be reduced to account for the loss of gain margin brought about by the discrete elements. Other conclusions of the study are: (i) the HHC is effective in quickly reducing vibrations, at least at its design condition, although the time constants associated with the closed loop transient response indicate closed loop bandwidth to be 1 rad/sec on average, thus overlapping with FCS or pilot bandwidths, and raising the issue of potential interactions; (ii) a linearized model of helicopter dynamics is adequate for HHC design, as long as the periodicity of the system is correctly taken into account, i

  2. Development and application of an analysis of axisymmetric body effects on helicopter rotor aerodynamics using modified slender body theory (United States)

    Yamauchi, G.; Johnson, W.


    A computationally efficient body analysis designed to couple with a comprehensive helicopter analysis is developed in order to calculate the body-induced aerodynamic effects on rotor performance and loads. A modified slender body theory is used as the body model. With the objective of demonstrating the accuracy, efficiency, and application of the method, the analysis at this stage is restricted to axisymmetric bodies at zero angle of attack. By comparing with results from an exact analysis for simple body shapes, it is found that the modified slender body theory provides an accurate potential flow solution for moderately thick bodies, with only a 10%-20% increase in computational effort over that of an isolated rotor analysis. The computational ease of this method provides a means for routine assessment of body-induced effects on a rotor. Results are given for several configurations that typify those being used in the Ames 40- by 80-Foot Wind Tunnel and in the rotor-body aerodynamic interference tests being conducted at Ames. A rotor-hybrid airship configuration is also analyzed.

  3. Physician staffed helicopter emergency medical service dispatch via centralised control or directly by crew – case identification rates and effect on the Sydney paediatric trauma system

    Directory of Open Access Journals (Sweden)

    Garner Alan A


    Full Text Available Abstract Background Severe paediatric trauma patients benefit from direct transport to dedicated Paediatric Trauma Centres (PTC. Parallel case identification systems utilising paramedics from a centralised dispatch centre versus the crew of a physician staffed Helicopter Emergency Medical Service (HEMS allowed comparison of the two systems for case identification rates and subsequent timeliness of direct transfer to a PTC. Methods Paediatric trauma patients over a two year period from the Sydney region with an Injury Severity Score (ISS > 15 were retrospectively identified from a state wide trauma registry. Overall paediatric trauma system performance was assessed by comparisons of the availability of the physician staffed HEMS for patient characteristics, transport mode (direct versus indirect and the times required for the patient to arrive at the paediatric trauma centre. The proportion of patients transported directly to a PTC was compared between the times that the HEMS service was available versus the time that it was unavailable to determine if the HEMS system altered the rate of direct transport to a PTC. Analysis of variance was used to compare the identifying systems for various patient characteristics when the HEMS was available. Results Ninety nine cases met the inclusion criteria, 44 when the HEMS system was operational. Patients identified for physician response by the HEMS system were significantly different to those that were not identified with higher median ISS (25 vs 18, p = 0.011, and shorter times to PTC (67 vs 261mins, p = 0.015 and length of intensive care unit stays (2 vs 0 days, p = 0.045. Of the 44 cases, 21 were not identified, 3 were identified by the paramedic system and 20 were identified by the HEMS system, (P  Conclusions Physician staffed HEMS crew dispatch is significantly more likely to identify cases of severe paediatric trauma and is associated with a greater proportion of transports

  4. Ergonomics, safety, and resilience in the helicopter offshore transportation system of Campos Basin. (United States)

    Gomes, José Orlando; Huber, Gilbert J; Borges, Marcos R S; de Carvalho, Paulo Victor R


    Air transportation of personnel to offshore oil platforms is one of the major hazards of this kind of endeavor. Pilot performance is a key factor in the safety of the transportation system. This study seeks to identify the ergonomic factors present in pilots' activities that may in some way compromise or enhance their performance, the constraints and affordances which they are subject to; and where possible to link these to their associated risk factors. Methodology adopted in this project studies work in its context. It is a merging of Activity Analysis (Guerin et al. 2001) of European tradition with Cognitive Task Analysis (CTA - articulated with the recent approaches to cognitive systems engineering developed by Professors David Woods and Erik Hollnagel. Fifty-five hours of field interviews provided the input for analysis. Sixteen ergonomic constraints were identified, some cognitive, some physical, all considered relevant by the research subjects and expert advisers. Although the safety record of the personnel transportation system studied is considered acceptable, there is low hanging fruit to be picked which can help improve the system's safety.

  5. Input Shaping for Helicopter Slung Load Swing Reduction

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon


    dampen swing. Simulations and flight tests show the effectiveness of the input shaping applied to a small scale autonomous helicopter slung load system. Both simulations and flight verifications shows significant slung load swing reduction using the proposed trajectory shaping over over flight without......This chapter presents a feedforward swing reducing control system for augmenting already existing helicopter controllers and enables slung load flight with autonomous helicopters general cargo transport. The feedforward controller is designed to avoid excitation of the lightly damped modes...

  6. The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: Boeing Helicopters airframe finite element modeling (United States)

    Gabel, R.; Lang, P.; Reed, D.


    Mathematical models based on the finite element method of structural analysis, as embodied in the NASTRAN computer code, are routinely used by the helicopter industry to calculate airframe static internal loads used for sizing structural members. Historically, less reliance has been placed on the vibration predictions based on these models. Beginning in the early 1980's NASA's Langley Research Center initiated an industry wide program with the objective of engendering the needed trust in vibration predictions using these models and establishing a body of modeling guides which would enable confident future prediction of airframe vibration as part of the regular design process. Emphasis in this paper is placed on the successful modeling of the Army/Boeing CH-47D which showed reasonable correlation with test data. A principal finding indicates that improved dynamic analysis requires greater attention to detail and perhaps a finer mesh, especially the mass distribution, than the usual stress model. Post program modeling efforts show improved correlation placing key modal frequencies in the b/rev range with 4 percent of the test frequencies.

  7. Detection of Forward Flight Limitations of Unmanned Helicopters


    Voigt, Andreas; Dauer, Johann; Krenik, Alex; Dittrich, Jörg Steffen


    In this paper, a method is proposed to determine the flight envelope limitations for steady forward flight with the purpose of performing a flight envelope expansion. First, the rotary wing system is analyzed. In this paper, an intermeshing rotor configuration, a SwissDrones Dragon 50, is used to demonstrate the approach. Next, relevant limitations of the forward flight are reviewed and analyzed with the help of the Helicopter Overall Simulation Tool (HOST). From this analysis, relevant measu...

  8. Neural network-based optimal adaptive output feedback control of a helicopter UAV. (United States)

    Nodland, David; Zargarzadeh, Hassan; Jagannathan, Sarangapani


    Helicopter unmanned aerial vehicles (UAVs) are widely used for both military and civilian operations. Because the helicopter UAVs are underactuated nonlinear mechanical systems, high-performance controller design for them presents a challenge. This paper introduces an optimal controller design via an output feedback for trajectory tracking of a helicopter UAV, using a neural network (NN). The output-feedback control system utilizes the backstepping methodology, employing kinematic and dynamic controllers and an NN observer. The online approximator-based dynamic controller learns the infinite-horizon Hamilton-Jacobi-Bellman equation in continuous time and calculates the corresponding optimal control input by minimizing a cost function, forward-in-time, without using the value and policy iterations. Optimal tracking is accomplished by using a single NN utilized for the cost function approximation. The overall closed-loop system stability is demonstrated using Lyapunov analysis. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control design for trajectory tracking.

  9. Military display market segment: helicopters (United States)

    Desjardins, Daniel D.; Hopper, Darrel G.


    The military display market is analyzed in terms of one of its segments: helicopter displays. Parameters requiring special consideration, to include luminance ranges, contrast ratio, viewing angles, and chromaticity coordinates, are examined. Performance requirements for rotary-wing displays relative to several premier applications are summarized. Display sizes having aggregate defense applications of 5,000 units or greater and having DoD applications across 10 or more platforms, are tabulated. The issue of size commonality is addressed where distribution of active area sizes across helicopter platforms, individually, in groups of two through nine, and ten or greater, is illustrated. Rotary-wing displays are also analyzed by technology, where total quantities of such displays are broken out into CRT, LCD, AMLCD, EM, LED, Incandescent, Plasma and TFEL percentages. Custom, versus Rugged commercial, versus commercial off-the-shelf designs are contrasted. High and low information content designs are identified. Displays for several high-profile military helicopter programs are discussed, to include both technical specifications and program history. The military display market study is summarized with breakouts for the helicopter market segment. Our defense-wide study as of March 2004 has documented 1,015,494 direct view and virtual image displays distributed across 1,181 display sizes and 503 weapon systems. Helicopter displays account for 67,472 displays (just 6.6% of DoD total) and comprise 83 sizes (7.0% of total DoD) in 76 platforms (15.1% of total DoD). Some 47.6% of these rotary-wing applications involve low information content displays comprising just a few characters in one color; however, as per fixed-wing aircraft, the predominant instantiation involves higher information content units capable of showing changeable graphics, color and video.

  10. Simulation validation and flight prediction of UH-60A Black Hawk helicopter/slung load characteristics


    Tyson, Peter H.


    Helicopter/slung load systems are two body systems in which the slung load adds its rigid body dynamics, aerodynamics, and sling stretching dynamics to the helicopter. The slung load can degrade helicopter handling qualities and reduce the flight envelope of the helicopter. Confirmation of system stability parameters and envelope is desired, but flight test evaluation is time consuming and costly. A simulation model validated for handling quality assessments would significantly reduce resourc...

  11. Helicopter stability during aggressive maneuvers (United States)

    Mohan, Ranjith

    The dissertation investigates helicopter trim and stability during level bank-angle and diving bank-angle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: (1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, (2) to correlate the trim predictions with the UH-60A flight test data, and (3) to demonstrate the feasibility of routinely using the exact fast-Floquet periodic eigenvector method for mode identification in the stability analysis. The UH-60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERA-Edlin (Equations Differentielles Lineaires) and Leishman-Beddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented.

  12. Progress in helicopter infrared signature suppression

    Directory of Open Access Journals (Sweden)

    Zhang Jingzhou


    Full Text Available Due to their low-attitude and relatively low-speed fight profiles, helicopters are subjected to serious threats from radio, infrared (IR, visual, and aural detection and tracking. Among these threats, infrared detection and tracking are regarded as more crucial for the survivability of helicopters. In order to meet the requirements of infrared stealth, several different types of infrared suppressor (IRS for helicopters have been developed. This paper reviews contemporary developments in this discipline, with particular emphasis on infrared signature suppression, advances in mixer-ejectors and prediction for helicopters. In addition, several remaining challenges, such as advanced IRS, emissivity optimization technique, helicopter infrared characterization, etc., are proposed, as an initial guide and stimulation for future research. In the future, the comprehensive infrared suppression in the 3–5 μm and 8–14 μm bands will doubtfully become the emphasis of helicopter stealth. Multidisciplinary optimization of a complete infrared suppression system deserves further investigation.

  13. Rice Crop Field Monitoring System with Radio Controlled Helicopter Based Near Infrared Cameras Through Nitrogen Content Estimation and Its Distribution Monitoring

    Directory of Open Access Journals (Sweden)

    Kohei Arai


    Full Text Available Rice crop field monitoring system with radio controlled helicopter based near infrared cameras is proposed together with nitrogen content estimation method for monitoring its distribution in the field in concern. Through experiments at the Saga Prefectural Agricultural Research Institute: SPARI, it is found that the proposed system works well for monitoring nitrogen content in the rice crop which indicates quality of the rice crop and its distribution in the field in concern. Therefore, it becomes available to maintain the rice crop fields in terms of quality control.

  14. Sliding mode tracking control for miniature unmanned helicopters

    Directory of Open Access Journals (Sweden)

    Bin Xian


    Full Text Available A sliding mode control design for a miniature unmanned helicopter is presented. The control objective is to let the helicopter track some predefined velocity and yaw trajectories. A new sliding mode control design method is developed based on a linearized dynamic model. In order to facilitate the control design, the helicopter’s dynamic model is divided into two subsystems, such as the longitudinal-lateral and the heading-heave subsystem. The proposed controller employs sliding mode control technique to compensate for the immeasurable flapping angles’ dynamic effects and external disturbances. The global asymptotic stability (GAS of the closed-loop system is proved by the Lyapunov based stability analysis. Numerical simulations demonstrate that the proposed controller can achieve superior tracking performance compared with the proportional-integral-derivative (PID and linear-quadratic regulator (LQR cascaded controller in the presence of wind gust disturbances.

  15. Sliding mode tracking control for miniature unmanned helicopters

    Institute of Scientific and Technical Information of China (English)

    Xian Bin; Guo Jianchuan; Zhang Yao; Zhao Bo


    A sliding mode control design for a miniature unmanned helicopter is presented. The control objective is to let the helicopter track some predefined velocity and yaw trajectories. A new sliding mode control design method is developed based on a linearized dynamic model. In order to facilitate the control design, the helicopter’s dynamic model is divided into two subsystems, such as the longitudinal-lateral and the heading-heave subsystem. The proposed controller employs sliding mode control technique to compensate for the immeasurable flapping angles’ dynamic effects and external disturbances. The global asymptotic stability (GAS) of the closed-loop system is proved by the Lyapunov based stability analysis. Numerical simulations demonstrate that the proposed controller can achieve superior tracking performance compared with the proportional-integral-derivative (PID) and linear-quadratic regulator (LQR) cascaded controller in the presence of wind gust disturbances.

  16. Lift capability prediction for helicopter rotor blade-numerical evaluation (United States)

    Rotaru, Constantin; Cîrciu, Ionicǎ; Luculescu, Doru


    The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can't be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

  17. Application of the ABC helicopter to the emergency medical service role (United States)

    Levine, L. S.


    Attention is called to the use of helicopters in transporting the sick and injured to medical facilities. It is noted that the helicopter's speed of response and delivery increases patient survival rates and may reduce the cost of medical care and its burden on society. Among the vehicle characteristics desired for this use are a cruising speed of 200 knots, a single engine hover capability at 10,000 ft, and an absence of a tail rotor. Three designs for helicopters incorporating such new technologies as digital/optical control systems, all composite air-frames, and third-generation airfoils are presented. A sensitivity analysis is conducted to show the effect of design speed, mission radius, and single engine hover capability on vehicle weight, fuel consumption, operating costs, and productivity.

  18. Design and preliminary tests of a blade tip air mass injection system for vortex modification and possible noise reduction on a full-scale helicopter rotor (United States)

    Pegg, R. J.; Hosier, R. N.; Balcerak, J. C.; Johnson, H. K.


    Full-scale tests were conducted on the Langley helicopter rotor test facility as part of a study to evaluate the effectiveness of a turbulent blade tip air mass injection system in alleviating the impulsive noise (blade slap) caused by blade-vortex interaction. Although blade-slap conditions could not be induced during these tests, qualitative results from flow visualization studies using smoke showed that the differential velocity between the jet velocity and the rotor tip speed was a primary parameter controlling the vortex modification.

  19. Small-Scale Helicopter Automatic Autorotation: Modeling, Guidance, and Control

    NARCIS (Netherlands)

    Taamallah, S.


    Our research objective consists in developing a, model-based, automatic safety recovery system, for a small-scale helicopter Unmanned Aerial Vehicle (UAV) in autorotation, i.e. an engine OFF flight condition, that safely flies and lands the helicopter to a pre-specified ground location. In pursuit o

  20. Geometric optimisation of a gurney flap henge-less deployment system for a helicopter model blade

    NARCIS (Netherlands)

    Paternoster, A.R.A.; Loendersloot, R.; Boer, de A.; Akkerman, R.


    Following a comparative study on shape morphing and adaptive systems to improve rotorcraft efficiency, the Green Rotorcraft consortium has selected the Gurney flap technology as demonstrator of a smart adaptive rotorblade within the Clean Sky Joint Technology Initiative [1]. The aim of such a system

  1. Geometric optimisation of a gurney flap hinge-less deployment system for a helicopter model blade

    NARCIS (Netherlands)

    Paternoster, Alexandre; Loendersloot, Richard; de Boer, Andries; Akkerman, Remko


    Following a comparative study on shape morphing and adaptive systems to improve rotorcraft efficiency, the Green Rotorcraft consortium has selected the Gurney flap technology as demonstrator of a smart adaptive rotorblade within the Clean Sky Joint Technology Initiative [1]. The aim of such a system

  2. 基于虚拟仪器技术的直升机电源试验系统设计%Design of helicopter power supply test system based on virtual instrument technology

    Institute of Scientific and Technical Information of China (English)

    陈超; 黄建; 梁旭


    At present ,there are still many problems in the helicopter power supply testing ,such as multiple test items , complex test equipment ,long test period and so on .If virtual instrument technology is applied to the design of the heli-copter power supply test system ,it would improve the test efficiency and shorten the test period .The test system de-signed in this paper use the PLC to control the switch of power supply circuits and test programs ,use the signal condi-tioning circuits and PXI devices to acquire data ,use the software developed on the CVI platform to analysis and display the data dynamically .In addition ,relevant assessment strategies are used for the evaluation of specified performance and comprehensive performance .The test system can provide technical support and scientific basis for the use and mainte-nance of the helicopter power system ,possessing a good application value .%目前 ,直升机电源系统的测试面临着测试项目多、测试设备复杂、测试周期长等诸多问题 ,如果将虚拟仪器技术应用于直升机电源测试系统的设计 ,将大大的提高测试效率和缩短测试周期.设计的测试系统通过PLC来控制供电电路的切换和测试项目的转换 ,用信号调理电路和PXI板卡来实现数据的采集 ,在CVI平台上开发软件来实现数据的分析、处理和动态显示 ,并且利用相关评估策略对电源系统指定性能和综合性能进行了评估.该试验系统能够为直升机电源系统的使用和维修等环节提供技术支持和科学依据 ,有很好的应用价值.

  3. 直升机尾传动系统扭转振动建模与特性%Torsional vibration characteristics analyzing and modeling for helicopter tail drive system

    Institute of Scientific and Technical Information of China (English)

    朱自冰; 朱如鹏; 鲍和云


    The helicopter tail drive system was simplified to a series system with shaft section and equivalent disk.A equivalent dynamic analysis model with multiple degrees of freedom, in which the transmission error of meshing gear pair and meshing stiffness of tail-decelerated gear were included, was established for this simplified helicopter tail drive system.According to the torsional dynamics equation of helicopter tail drive system, the torsional vibration response of system was obtained, and the torsional vibration characteristics of the system with different torsional stiffness of the shaft and meshing stiffness of the gear were discussed.The following conclusions may be drawn from the analysis result.The torsional displacement of tail rotor is larger than the torsional displacement of driven gear of tail gearbox, namely the vibration response of output gear of tail gear box is larger than the input gear.The variation tendency is opposite of the torsional angle displacement between the equivalent disk connected to the horizontal shaft and oblique shaft respectively.The meshing stiffness has more influence on the system than the shaft torsional stiffness, it should be taken account into the modeling of helicopter tail drive system.%将直升机传动系统简化为轴段和当量圆盘的串联系统,建立了直升机尾传动系统扭转振动的等效多自由度动力学模型.模型中考虑了啮合齿轮对的综合啮合误差激励和尾减齿轮的啮合刚度,针对系统的扭转动力学方程,求得了系统的扭转振动响应,分析了直升机尾传动系统在轴的不同扭转刚度和齿轮的不同啮合刚度下的扭转振动的特性,结果表明:与尾斜轴相联的当量圆盘的扭转角位移始终比与水平轴相联的当量圆盘的扭转角位移的数值大,即与尾斜轴相联的尾减输出齿轮振动大于输入齿轮;当轴的扭转刚度变化时,水平轴相联的当量圆盘与尾斜轴相联的当量

  4. A theoretical analysis of the electromagnetic environment of the AS330 super Puma helicopter external and internal coupling (United States)

    Flourens, F.; Morel, T.; Gauthier, D.; Serafin, D.


    Numerical techniques such as Finite Difference Time Domain (FDTD) computer programs, which were first developed to analyze the external electromagnetic environment of an aircraft during a wave illumination, a lightning event, or any kind of current injection, are now very powerful investigative tools. The program called GORFF-VE, was extended to compute the inner electromagnetic fields that are generated by the penetration of the outer fields through large apertures made in the all metallic body. Then, the internal fields can drive the electrical response of a cable network. The coupling between the inside and the outside of the helicopter is implemented using Huygen's principle. Moreover, the spectacular increase of computer resources, as calculations speed and memory capacity, allows the modellization structures as complex as these of helicopters with accuracy. This numerical model was exploited, first, to analyze the electromagnetic environment of an in-flight helicopter for several injection configurations, and second, to design a coaxial return path to simulate the lightning aircraft interaction with a strong current injection. The E field and current mappings are the result of these calculations.

  5. Government Competitive Test Utility Tactical Transport Aircraft System (UTTAS). Sikorsky YUH-60A Helicopter (United States)


    IN.e COPESO COMPRESOR OICN133 O-CN-G PORT... - control valve that provides regulated air ilow to the pneumatic start system. Pressure regulation...Governing Characteristics 17. In general. the HMU provides for gas generator control in the areas of acceleration limiting. stall and flameout protection...blade stall are not significant. During this evaluation, minor trends indicating an influence by compressibility and blade stall were noted. However

  6. 78 FR 65180 - Airworthiness Directives; MD Helicopters, Inc., Helicopters (United States)


    ... condition, vibration, loss of tail rotor pitch control, and loss of directional control of the helicopter...-047-AD; Amendment 39-17606; AD 2013-19-24] RIN 2120-AA64 Airworthiness Directives; MD Helicopters, Inc., Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We...

  7. 78 FR 27867 - Airworthiness Directives; MD Helicopters Inc. Helicopters (United States)


    ..., leading to vibration, loss of tail rotor pitch control, and subsequent loss of tail rotor and helicopter... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; MD Helicopters Inc. Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking...

  8. Light Helicopter Family Trade-Off Analysis. Volume 8. Appendices S and T (United States)


    3 ^ r-i m »n o^ oo •* oo i-< oo oo r» Omo ^coencpencM PI 00 CM ^ 00 CM O •< C •* m oo •-4...The portion of the maintenance manpower strength dedicated to the LHX: Portion of LHX aircraft in the AHB - 34/37 From figure T-5, the...fell out of the analysis was the maximum value that could be afforded without any increase in personnel strength . Likewise, any lower

  9. Distribution of the 134Cs/137Cs ratio around the Fukushima Daiichi nuclear power plant using an unmanned helicopter radiation monitoring system (United States)

    Torii, T.; Nishizawa, Y.


    Many radioactive substances were released by the Fukushima Daiichi nuclear power plant accident occurred on March 11, 2011 in the atmosphere. A lot of short half-life nuclides which are 131I, 132Te (132I) and 133I, etc., in addition to longer half-lived nuclides such as 134Cs and 137Cs. The estimated release amount of these nuclides from the reactor 1st to 3rd unit is reported, but it's found to be quite different in the short half-lived nuclides by the reactor units. Because the radioactivity ratio of 134Cs and 137Cs was slight different between the reactor units, it can be considered that the valuable source is obtained by the measurement of 134Cs/137Cs ratio in the environment around the Fukushima Daiichi nuclear power station at the present stage when the nuclides with short half-lives had already decayed. We have measured high-resolution gamma-ray spectrum using an unmanned helicopter equipped with LaBr3(Ce) detector in a 3-km range from the power station which was near to the release source of the radioactive cesium. Because the LaBr3(Ce) detector has high resolution of gamma rays, the discrimination of many nuclides is possible. In addition, there is extremely much number of the data provided by the distribution measurement with the unmanned helicopter. Because a new map was illustrated by the analysis of the 134Cs/137Cs ratio, we report the outline.

  10. Natural gas has an optical fingerprint. CHARM {sup registered}, the helicopter-borne remote gas detection system; Erdgas hat einen optischen Fingerabdruck. CHARM {sup registered}, das hubschraubergetragene Gasferndetektionssystem

    Energy Technology Data Exchange (ETDEWEB)

    Zirnig, W.; Kordulla, K. [E.ON Ruhrgas, Dorsten (Germany); Ulbricht, M. [Adlares GmbH, Teltow (Germany)


    Together with the German Aerospace Centre DLR and the laser company Adlares, E.ON Ruhrgas AG has developed a novel infrared laser remote gas sensing system which can be used during aerial inspections by helicopter to check natural gas pipelines for tightness, as required by law particularly in built-up areas. Based on geographic information systems with digital maps containing detailed data on pipeline routes, and in combination with the satellite reference service Ascos, which provides Germany-wide reference data for highly accurate satellite-based surveying, a precise automatic navigation was supplied for the remote gas detection system. Thus, CHARM offers new efficient ways of looking after natural gas pipeline systems. (orig.)

  11. Simulation of Flow around Isolated Helicopter Fuselage

    Directory of Open Access Journals (Sweden)

    Garipov A.O.


    Full Text Available Low fuselage drag has always been a key target of helicopter manufacturers. Therefore, this paper focuses on CFD predictions of the drag of several components of a typical helicopter fuselage. In the first section of the paper, validation of the obtained CFD predictions is carried out using wind tunnel measurements. The measurements were carried out at the Kazan National Research Technical University n.a. A. Tupolev. The second section of the paper is devoted to the analysis of drag contributions of several components of the ANSAT helicopter prototype fuselage using the RANS approach. For this purpose, several configurations of fuselages are considered with different levels of complexity including exhausts and skids. Depending on the complexity of the considered configuration and CFD mesh both the multi-block structured HMB solver and the unstructured commercial tool Fluent are used. Finally, the effect of an actuator disk on the predicted drag is addressed.

  12. Implementation of a blade element UH-60 helicopter simulation on a parallel computer architecture in real-time (United States)

    Moxon, Bruce C.; Green, John A.


    A high-performance platform for development of real-time helicopter flight simulations based on a simulation development and analysis platform combining a parallel simulation development and analysis environment with a scalable multiprocessor computer system is described. Simulation functional decomposition is covered, including the sequencing and data dependency of simulation modules and simulation functional mapping to multiple processors. The multiprocessor-based implementation of a blade-element simulation of the UH-60 helicopter is presented, and a prototype developed for a TC2000 computer is generalized in order to arrive at a portable multiprocessor software architecture. It is pointed out that the proposed approach coupled with a pilot's station creates a setting in which simulation engineers, computer scientists, and pilots can work together in the design and evaluation of advanced real-time helicopter simulations.

  13. Neuro-optimal control of helicopter UAVs (United States)

    Nodland, David; Ghosh, Arpita; Zargarzadeh, H.; Jagannathan, S.


    Helicopter UAVs can be extensively used for military missions as well as in civil operations, ranging from multirole combat support and search and rescue, to border surveillance and forest fire monitoring. Helicopter UAVs are underactuated nonlinear mechanical systems with correspondingly challenging controller designs. This paper presents an optimal controller design for the regulation and vertical tracking of an underactuated helicopter using an adaptive critic neural network framework. The online approximator-based controller learns the infinite-horizon continuous-time Hamilton-Jacobi-Bellman (HJB) equation and then calculates the corresponding optimal control input that minimizes the HJB equation forward-in-time. In the proposed technique, optimal regulation and vertical tracking is accomplished by a single neural network (NN) with a second NN necessary for the virtual controller. Both of the NNs are tuned online using novel weight update laws. Simulation results are included to demonstrate the effectiveness of the proposed control design in hovering applications.

  14. Passive suppression of helicopter ground resonance using nonlinear energy sinks attached on the helicopter blades (United States)

    Bergeot, B.; Bellizzi, S.; Cochelin, B.


    This paper investigates the passive control of a rotor instability named helicopter Ground Resonance (GR). The passive device consists of a set of essential cubic nonlinear absorbers named Nonlinear Energy Sinks (NES) each of them positioned on a blade. A dynamic model reproducing helicopter GR instability is presented and transformed to a time-invariant nonlinear system using a multi-blade coordinate transformation based on Fourier transform mapping the dynamic state variables into a non-rotating reference frame. Combining complexification, slow/fast partition of the dynamics and averaging procedure, a reduced model is obtained which allowed us to use the so-called geometric singular perturbation analysis to characterize the steady state response regimes. As in the case of a NES attached to the fuselage, it is shown that under suitable conditions, GR instability can be completely suppressed, partially suppressed through periodic response or strongly modulated response. Relevant analytical results are compared, for validation purposes, to direct integration of the reference and reduced models.

  15. Overview: Applications of numerical optimization methods to helicopter design problems (United States)

    Miura, H.


    There are a number of helicopter design problems that are well suited to applications of numerical design optimization techniques. Adequate implementation of this technology will provide high pay-offs. There are a number of numerical optimization programs available, and there are many excellent response/performance analysis programs developed or being developed. But integration of these programs in a form that is usable in the design phase should be recognized as important. It is also necessary to attract the attention of engineers engaged in the development of analysis capabilities and to make them aware that analysis capabilities are much more powerful if integrated into design oriented codes. Frequently, the shortcoming of analysis capabilities are revealed by coupling them with an optimization code. Most of the published work has addressed problems in preliminary system design, rotor system/blade design or airframe design. Very few published results were found in acoustics, aerodynamics and control system design. Currently major efforts are focused on vibration reduction, and aerodynamics/acoustics applications appear to be growing fast. The development of a computer program system to integrate the multiple disciplines required in helicopter design with numerical optimization technique is needed. Activities in Britain, Germany and Poland are identified, but no published results from France, Italy, the USSR or Japan were found.

  16. GARTEUR Helicopter Cooperative Research


    Pahlke, Klausdieter


    This paper starts with an overview about the general structure of the Group for Aeronautical Research and Technology in EURope (GARTEUR). The focus is on the activities related to rotorcraft which are managed in the GARTEUR Helicopter Group of Responsables (HC GoR). The research activities are carried out in so-called Action Groups. Out of the 5 Action Groups which ended within the last four years results generated in the Helicopter Action Groups HC(AG14) “Methods for Refinement of Structural...

  17. Flying control of small-type helicopter by detecting its in-air natural features

    Directory of Open Access Journals (Sweden)

    Chinthaka Premachandra


    Full Text Available Control of a small type helicopter is an interesting research area in unmanned aerial vehicle development. This study aims to detect a more typical helicopter unequipped with markers as a means by which to resolve the various issues of the prior studies. Accordingly, we propose a method of detecting the helicopter location and pose through using an infrastructure camera to recognize its in-air natural features such as ellipse traced by the rotation of the helicopter's propellers. A single-rotor system helicopter was used as the controlled airframe in our experiments. Here, helicopter location is measured by detecting the main rotor ellipse center and pose is measured following relationship between the main rotor ellipse and the tail rotor ellipse. Following these detection results we confirmed the hovering control possibility of the helicopter through experiments.

  18. 29 CFR 1910.183 - Helicopters. (United States)


    ... the system with the employees in advance of hoisting the load. This applies to both radio and hand... instruct employees, and shall ensure, that whenever approaching or leaving a helicopter which has its... employer shall ensure its use by employees receiving the load. Personal protective equipment shall...

  19. 77 FR 64439 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model Helicopters (United States)


    ... warning system. For helicopters with a single or dual Automatic Flight Control System (AFCS) with a Flight... attitude direction indicators airspeed indicators; Leak testing the pilot pitot static system; and Power-up... with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices...

  20. Input Shaping for Helicopter Slung Load Swing Reduction

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon


    This chapter presents a feedforward swing reducing control system for augmenting already existing helicopter controllers and enables slung load flight with autonomous helicopters general cargo transport. The feedforward controller is designed to avoid excitation of the lightly damped modes...... of the system by shaping the reference trajectory using robust input shaping. It is developed as part of an integrated adaptive control system consisting of state estimator, feedforward, and feedback controller capable of simultaneously preventing swing in the slung load from helicopter motion and actively...... dampen swing. Simulations and flight tests show the effectiveness of the input shaping applied to a small scale autonomous helicopter slung load system. Both simulations and flight verifications shows significant slung load swing reduction using the proposed trajectory shaping over over flight without...

  1. Aircrew-aircraft integration issues in future US Army helicopters (United States)

    Hartzell, E. J.; Aiken, E. W.; Voorhees, J. W.


    Some human factors research issues, the resolution of which will be vital to the successful operation of future military helicopters are reviewed. Understanding and reducing the helicopter pilot's workload is examined by a diverse program directed at answering some of the more fundamental questions relating to the transfer displays and interactions between pilot and automated systems. The results of three experimental studies which address the issues of display control compatibility, characteristics of integrated controllers, and voice systems are presented.

  2. Flight dynamics model and system identification of longitudinal and lateral channels for a small-scale coaxial helicopter%小型共轴式直升机纵横向动力学建模与辨识

    Institute of Scientific and Technical Information of China (English)

    聂资; 陈铭; 李仁府


    Using perturbation approach, a linearized flight dynamics model was formulated for the non-linear coaxial helicopter flight control problem. Based on mathematical parametric model of the rotorcraft, the system identification model was obtained by utilizing the input and output data of longitudinal and lateral channel in flight test. The analysis and validation of the above two models in the time domain was given by computer simulation. The stability derivatives, control derivatives and the system eigenvalues were computed for the stability analysis of the helicopter. Results show that the mathematical model can reflect the dynamic characteristics of the longitudinal and lateral channels, based on which the system identification model can be a mathematical model for autonomous flight control system design.%运用经典的叶素法和一阶谐波理论,建立了悬停状态下某小型共轴式直升机纵横向通道的理论计算模型;同时根据飞行试验中采集的直升机输入输出数据,以参数化理论模型为基础,运用系统辨识的方法得到了该机纵横向通道模型.通过计算机仿真,分别对理论计算模型和系统辨识模型进行了时域验证和分析,并比较了2种模型的稳定性导数、操纵导数及特征根,对该直升机的稳定性进行了分析.研究表明:所建立的小型共轴式直升机纵横向通道的理论计算模型能够反映该机悬停状态下纵横向通道的动态特性,以此为基础建立的系统辨识模型可以作为飞行控制系统纵横向通道控制的数学模型.

  3. Loads and Performance Data from a Wind-Tunnel Test of Generic Model Helicopter Rotor Blades (United States)

    Yeager, William T., Jr.; Wilbur, Matthew L.


    An investigation was conducted in the NASA Langley Transonic Dynamics Tunnel to acquire data for use in assessing the ability of current and future comprehensive analyses to predict helicopter rotating-system and fixed-system vibratory loads. The investigation was conducted with a generic model helicopter rotor system using blades with rectangular planform, no built-in twist, uniform radial distribution of mass and stiffnesses, and a NACA 0012 airfoil section. Rotor performance data, as well as mean and vibratory components of blade bending and torsion moments, fixed-system forces and moments, and pitch link loads were obtained at advance ratios up to 0.35 for various combinations of rotor shaft angle-of-attack and collective pitch. The data are presented without analysis.

  4. An Investigation of Multi-Axis Isometric Side-Arm Controllers in a Variable Stability Helicopter(Etude de Systeme de Controle Lateral Isometrique a Axes Multiples a Bord d’un Helicoptere a Stabilite Variable). (United States)


    helicopter pilot and consequently has the status of an international standard. The benefits gained in any substantial deviation from this arrangement must be...questions which were designed to highlight the benefits and deficiencies of the multi-axis isometric control system. The questions and abbreviated...34 ambidextrous " by installing controllers for both left and right hand operation. Such a system would have a fundamental influence on cockpit layout since

  5. 基于DE算法的共轴直升机模型辨识及精度分析%Coaxial helicopter model identification based on differential evolution algorithm and accuracy analysis

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 蒙志君; 武哲


    由于共轴直升机特有的旋翼布局引发了上下旋翼间强烈的气动干扰,采用传统的理论分析和风洞试验的方法难以获得适用于共轴直升机控制系统的飞行动力学模型.为此,设计了飞行扫频试验,根据飞行试验数据得到了悬停状态下包含共轴直升机飞行动力学模型耦合特性的非参数频率响应,运用仿生智能计算方法中的微分进化(DE,Differential Evolution)算法拟合频率响应建立了悬停状态下的共轴直升机状态空间模型.利用Cramer-Rao边界和不灵敏度的相关理论进行分析计算,说明辨识得到的参数具有较高的精度和可信度.通过比较辨识模型的输出和实际飞行数据的结果,说明辨识得到的模型能充分反映共轴直升机的飞行动力学特性,可用于飞行品质评估和飞控系统设计.%The coaxial helicopter exists intense aerodynamic interaction between the upper and lower rotor,and it is difficult to establish the accurate dynamic model for flight control systems using the theory analysis and wind tunnel experiment.Frequency sweep flight experiment data was used to extract the non-parametric frequency responses that fully characterizes the coupled helicopter dynamics.A nonlinear search based on differential evolution algorithm for a linear state-space model which matches the frequency-response data set was conducted.Parameter insensitivity and Cramer-Rao bound analysis results have low values,indicating very good reliability of the identified model.The accuracy of the identified model is verified by comparing the model-predicted responses with the responses collected during flight experiments,and the model can be used for flight quality analysis and flight control system design.

  6. Helicopter Flight Control Research - A Demanding Application of Piloted Simulation. (United States)


    Sigma-8 digital computer (used to run the aircraft mathematical model) and an Applied Dynamics AD-4 analogue computer (used principally as a flexible...interface to cockpit instruments, and for motion and visual systems operation) (Fig 4). The first helicopter simulation to use a digital aircraft...34 Control Technology for helicopters. For fixed-wing aircraft, impresive claims were being made for electrically (and later optically) signalled control

  7. The scope of back pain in Navy helicopter pilots


    Phillips, Andrea S.


    Approved for public release; distribution is unlimited. Human Systems Integration Report This thesis investigates issues such as long hours in the cockpit, ineffective seat padding, Night Vision Goggle (NVG) use, and the constant vibrations involved in flying rotary wing aircraft. Pain is subjective and severity is difficult to compare between individuals. Does back pain affect safety of flight? In the military helicopter aviator community, 60-80% of helicopter pilots are estimated ...

  8. Design of a numeric simulation platform for integrated turbo-shaft engine/helicopter control system%涡轴发动机/直升机综合控制仿真平台设计

    Institute of Scientific and Technical Information of China (English)

    张海波; 姚文荣; 陈国强


    A control simulation platform is designed for UH-60 helicopter /T700 turbo-shaft engine integrated system numeric simulation. The simulation platform includes two parts; host computer program and slave computer program, and they are both developed by VC ++ programming language. Host computer program is composed by UH-60 helicopter and T700 turbo-shaft engine real-time mathematical model, and the slave computer program simulates the embedded engine model and main rotor dynamic model,and carries out a variety of online optimization modes. The two programs above communicate with each other in real time based on TCP/IP protocol, so the transient and state process can be simulated for the integrated helicopter and engine system subjecting to surrounding and control parameters. Simulation results in some optimization control modes are also given throughout the simulation platform, respectively, including those which improve the helicopter traditional performance. The main rotor speed are kept constant or not, and the fast power-tracking mode can improve the helicopter maneuverability. All the simulation results show clearly that the simulation platform can provide an feasible validation in the early stage to implement an new integrated engine /helicopter control system.%建立了UH-60直升机/T700涡轴发动机综合控制数字仿真平台.基于VC++环境开发了包含UH-60直升机/T700涡轴发动机综合实时模型的上位机程序,与运行机载涡轴发动机+旋翼实时模型及在线优化控制模式的下位机程序.两者基于TCP/IP协议实时通讯,可进行模拟实际直/发综合优化控制的数字仿真实验.在该数字仿真环境下,分别给出了提高直升机常规飞行性能的多种优化控制模式仿真、变旋翼转速优化控制以及快速功率跟随控制模式仿真,充分表明该平台可为新一代直/发综合系统的开发研制提供一个可靠的前期数字仿真验证.

  9. MMW radar enhanced vision systems: the Helicopter Autonomous Landing System (HALS) and Radar-Enhanced Vision System (REVS) are rotary and fixed wing enhanced flight vision systems that enable safe flight operations in degraded visual environments (United States)

    Cross, Jack; Schneider, John; Cariani, Pete


    Sierra Nevada Corporation (SNC) has developed rotary and fixed wing millimeter wave radar enhanced vision systems. The Helicopter Autonomous Landing System (HALS) is a rotary-wing enhanced vision system that enables multi-ship landing, takeoff, and enroute flight in Degraded Visual Environments (DVE). HALS has been successfully flight tested in a variety of scenarios, from brown-out DVE landings, to enroute flight over mountainous terrain, to wire/cable detection during low-level flight. The Radar Enhanced Vision Systems (REVS) is a fixed-wing Enhanced Flight Vision System (EFVS) undergoing prototype development testing. Both systems are based on a fast-scanning, threedimensional 94 GHz radar that produces real-time terrain and obstacle imagery. The radar imagery is fused with synthetic imagery of the surrounding terrain to form a long-range, wide field-of-view display. A symbology overlay is added to provide aircraft state information and, for HALS, approach and landing command guidance cuing. The combination of see-through imagery and symbology provides the key information a pilot needs to perform safe flight operations in DVE conditions. This paper discusses the HALS and REVS systems and technology, presents imagery, and summarizes the recent flight test results.

  10. Experimental Validation of a Compound Control Scheme for a Two-Axis Inertially Stabilized Platform with Multi-Sensors in an Unmanned Helicopter-Based Airborne Power Line Inspection System



    A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP) with multi-sensors applied to an unmanned helicopter (UH)-based airborne power line inspection (APLI) system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from ...

  11. Structural Dynamics Verification of Rotorcraft Comprehensive Analysis System (RCAS)

    Energy Technology Data Exchange (ETDEWEB)

    Bir, G. S.


    The Rotorcraft Comprehensive Analysis System (RCAS) was acquired and evaluated as part of an ongoing effort by the U.S Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) to provide state-of-the-art wind turbine modeling and analysis technology for Government and industry. RCAS is an interdisciplinary tool offering aeroelastic modeling and analysis options not supported by current codes. RCAS was developed during a 4-year joint effort among the U.S. Army's Aeroflightdynamics Directorate, Advanced Rotorcraft Technology Inc., and the helicopter industry. The code draws heavily from its predecessor 2GCHAS (Second Generation Comprehensive Helicopter Analysis System), which required an additional 14 years to develop. Though developed for the rotorcraft industry, its general-purpose features allow it to model or analyze a general dynamic system. Its key feature is a specialized finite element that can model spinning flexible parts. The code, therefore, appears particularly suited for wind turbines whose dynamics is dominated by massive flexible spinning rotors. In addition to the simulation capability of the existing codes, RCAS [1-3] offers a range of unique capabilities, including aeroelastic stability analysis, trim, state-space modeling, operating modes, modal reduction, multi-blade coordinate transformation, periodic-system-specific analysis, choice of aerodynamic models, and a controls design/implementation graphical interface.

  12. 76 FR 2607 - Airworthiness Directives; MD Helicopters, Inc. (MDHI) Model MD900 Helicopters (United States)


    ... System (VSCS) switches and turning off the autopilot (AP/SAS) switch; pulling certain AP/SAS circuit... flight to VFR, prohibiting use of the autopilot, and making changes to the RFM. For all helicopters, the...) Turn ON both VSCS switches. (b) If installed, de-energize the autopilot (AP/SAS) as follows:...


    Institute of Scientific and Technical Information of China (English)

    龚华军; 杨一栋


    阵风响应缓和研究对于具有强耦合和振动的直升机非常重要,阵风扰动不仅影响直升机的乘座品质和武器投放精度,而且影响直升机的疲劳载荷和强度.本文提出直升机抑制阵风扰动的最优控制律设计方法.优化性能指标要求在阵风扰动下驾驶员处法向过载、飞机姿态变化以及控制信号能量损耗最小.最终所综合的系统工程实现简便,只需在直升机姿态控制系统基础上增加垂直升降速率反馈通道即可.最后使用C语言实现控制律并进行半物理仿真, 仿真结果表明,控制律优化及数字化实现的效果是令人满意的.%Gust response alleviation is very important for helicopters which have strong coupling and vibration. Gust disturbance not only influences the ride quality and the precision of the weapon delivery, but also affects to the structural fatigue load and the strength. The method of an optimal control law to suppress the gust disturbance for helicopters is presented. The optimization requires the minimization of the vertical overload at the pilot′s seat, the attitude variation and the control energy consumption under the gust disturbance. Based on the original control system, the new system can be easily realized by adding a vertical speed feedback passage. In order to develop the real-time operational flight control system, the optimized control law is written in C language. The hybrid simulations prove that the performance of gust response alleviation and the efficiency of digitalization are satisfactory.

  14. Helicopter response to atmospheric turbulence (United States)

    Riaz, J.; Prasad, J. V. R.; Schrage, D. P.; Gaonkar, G. H.


    A new time-domain method for simulating cyclostationary turbulence as seen by a translating and rotating blade element has recently been developed for the case of one-dimensional spectral distribution. This paper extends the simulation method to the cases of two- and three-dimensional spectral distributions and presents validation results for the two-dimensional case. The statistics of an isolated rigid blade flapping response to turbulence are computed using a two-dimensional spectral representation of the von Karman turbulence model, and the results are compared with those obtained using the conventional space-fixed turbulence analysis. The new turbulence simulation method is used for predicting the Black Hawk helicopter response to atmospheric turbulence.

  15. Dynamics of a split torque helicopter transmission (United States)

    Krantz, Timothy L.


    Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

  16. [Functional dynamics of the pilots of heavy transport helicopters in the course of a flight shift]. (United States)

    Kamenskiĭ, Iu N


    Before and after flights about 300 crewmembers of heavy transport helicopters were examined, using psychophysiological and integral methods that yield professionally important information. During a flight shift the health state of helicopter pilots varies via three stages: habituation, initial decline and distinct lassitude, with the latter developing after 5 h flight load. In order to increase human reliability in the pilot-helicopter system, it is advisable to allow 4 h flight time during a flight shift onboard helicopters of the above type. In this case the pilot exposure to vibration effects will also be limited. The paper describes a maximally permissible spectrum of vibration velocity for a 4 h exposure.

  17. Subjective evaluation of helicopter blade slap noise (United States)

    Galloway, W. J.


    Several methods for adjusting EPNL to account for its underestimate of judged annoyance are applied to eight helicopter flyover noise signatures having various degrees of blade slap. A proposal for an impulsive noise correlation procedure based on a digital analysis of the flyover signal is investigated. When all data are combined, the proposal is little better than simply adding an arbitrary fixed adjustment of 3 decibels to EPNL.

  18. Helicopter vibration isolation: Design approach and test results (United States)

    Lee, C.-M.; Goverdovskiy, V. N.; Sotenko, A. V.


    This paper presents a strategy based on the approach of designing and inserting into helicopter vibration isolation systems mountable mechanisms with springs of adjustable sign-changing stiffness for system stiffness control. A procedure to extend the effective area of stiffness control is presented; a set of parameters for sensitivity analysis and practical mechanism design is formulated. The validity and flexibility of the approach are illustrated by application to crewmen seat suspensions and vibration isolators for equipment protection containers. The strategy provides minimization of vibrations, especially in the infra-low frequency range which is the most important for crewmen efficiency and safety of the equipment. This also would prevent performance degradation of some operating systems. The effectiveness is demonstrated through measured data obtained from development and parallel flight tests of new and operating systems.

  19. Helicopter individual-blade-control and its applications (United States)

    Ham, N. D.


    A new, advanced type of active control for helicopters and its applications are described. The system, based on previously developed M.I.T. Individual-Blade-Control hardware, employs blade-mounted accelerometers to sense blade motion and feeds back information to control blade pitch in such a manner as to reduce the response of selected blade modes. A linear model of the blade and control system dynamics is used to give guidance in the design process as well as to aid in analysis of experimental results. System performance in wind tunnel tests is described, and evidence is given of the system's ability to provide substantial reduction in blade modal responses, including blade bending vibration.

  20. World helicopter market study (United States)

    Cleary, B.; Pearson, R. W.; Greenwood, S. W.; Kaplan, L.


    The extent of the threat to the US helicopter industry posed by a determined effort by foreign manufacturers, European companies in particular, to supply their own domestic markets and also to penetrate export markets, including the USA is assessed. Available data on US and world markets for civil and military uses are collated and presented in both graphic and tabular form showing the past history of production and markets and, where forecasts are available, anticipated future trends. The data are discussed on an item-by-item basis and inferences are drawn in as much depth as appears justified.

  1. Helicopter vibration reduction using structural optimization with aeroelastic/multidisciplinary constraints - A survey (United States)

    Friedmann, Peretz P.


    This paper presents a survey of the state-of-the-art in the field of structural optimization when applied to vibration reduction of helicopters in forward flight with aeroelastic and multidisciplinary constraints. It emphasizes the application of the modern approach where the optimization is formulated as a mathematical programming problem, the objective function consists of the vibration levels at the hub, and behavior constraints are imposed on the blade frequencies and aeroelastic stability margins, as well as on a number of additional ingredients that can have a significant effect on the overall performance and flight mechanics of the helicopter. It is shown that the integrated multidisciplinary optimization of rotorcraft offers the potential for substantial improvements, which can be achieved by careful preliminary design and analysis without requiring additional hardware such as rotor vibration absorbers of isolation systems.

  2. Development of helicopter attitude axes controlled hover flight without pilot assistance and vehicle crashes (United States)

    Simon, Miguel

    In this work, we show how to computerize a helicopter to fly attitude axes controlled hover flight without the assistance of a pilot and without ever crashing. We start by developing a helicopter research test bed system including all hardware, software, and means for testing and training the helicopter to fly by computer. We select a Remote Controlled helicopter with a 5 ft. diameter rotor and 2.2 hp engine. We equip the helicopter with a payload of sensors, computers, navigation and telemetry equipment, and batteries. We develop a differential GPS system with cm accuracy and a ground computerized navigation system for six degrees of freedom (6-DoF) free flight while tracking navigation commands. We design feedback control loops with yet-to-be-determined gains for the five control "knobs" available to a flying radio-controlled (RC) miniature helicopter: engine throttle, main rotor collective pitch, longitudinal cyclic pitch, lateral cyclic pitch, and tail rotor collective pitch. We develop helicopter flight equations using fundamental dynamics, helicopter momentum theory and blade element theory. The helicopter flight equations include helicopter rotor equations of motions, helicopter rotor forces and moments, helicopter trim equations, helicopter stability derivatives, and a coupled fuselage-rotor helicopter 6-DoF model. The helicopter simulation also includes helicopter engine control equations, a helicopter aerodynamic model, and finally helicopter stability and control equations. The derivation of a set of non-linear equations of motion for the main rotor is a contribution of this thesis work. We design and build two special test stands for training and testing the helicopter to fly attitude axes controlled hover flight, starting with one axis at a time and progressing to multiple axes. The first test stand is built for teaching and testing controlled flight of elevation and yaw (i.e., directional control). The second test stand is built for teaching and

  3. Development, documentation and correlation of a NASTRAN vibration model of the AH-1G helicopter airframe (United States)

    Cronkhite, J. D.


    NASTRAN was evaluated for vibration analysis of the helicopter airframe. The first effort involved development of a NASTRAN model of the AH-1G helicopter airframe and comprehensive documentation of the model. The next effort was to assess the validity of the NASTRAN model by comparisons with static and vibration tests.

  4. An analytically linearized helicopter model with improved modeling accuracy (United States)

    Jensen, Patrick T.; Curtiss, H. C., Jr.; Mckillip, Robert M., Jr.


    An analytically linearized model for helicopter flight response including rotor blade dynamics and dynamic inflow, that was recently developed, was studied with the objective of increasing the understanding, the ease of use, and the accuracy of the model. The mathematical model is described along with a description of the UH-60A Black Hawk helicopter and flight test used to validate the model. To aid in utilization of the model for sensitivity analysis, a new, faster, and more efficient implementation of the model was developed. It is shown that several errors in the mathematical modeling of the system caused a reduction in accuracy. These errors in rotor force resolution, trim force and moment calculation, and rotor inertia terms were corrected along with improvements to the programming style and documentation. Use of a trim input file to drive the model is examined. Trim file errors in blade twist, control input phase angle, coning and lag angles, main and tail rotor pitch, and uniform induced velocity, were corrected. Finally, through direct comparison of the original and corrected model responses to flight test data, the effect of the corrections on overall model output is shown.

  5. 14 CFR Appendix F to Part 91 - Helicopter Flight Recorder Specifications (United States)


    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Helicopter Flight Recorder Specifications F Appendix F to Part 91 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Appendix F to Part 91—Helicopter Flight Recorder Specifications Parameters Range Installed system 1...

  6. Vertebral pain in helicopter pilots (United States)

    Auffret, R.; Delahaye, R. P.; Metges, P. J.; VICENS


    Pathological forms of spinal pain engendered by piloting helicopters were clinically studied. Lumbalgia and pathology of the dorsal and cervical spine are discussed along with their clinical and radiological signs and origins.

  7. Finite Element Analysis and Test on Dynamic Characteristics of Fuselage Frame of Unmanned Helicopter%某无人直升机机身框架动力学计算与试验研究

    Institute of Scientific and Technical Information of China (English)

    谢勤伟; 姜年朝; 周光明; 张逊; 王克选; 张志清


    The finite element model of structural dynamics of fuselage frame of unmanned helicopter was established and the natural frequencies and mode shapes of its first 6 orders were obtained. Compared with modal test, the maximum error of calculation was less than 3 %. It shows that the finite element model is correct and accurately reflects the structural dynamics character of the fuselage frame of unmanned helicopter. The computational natural frequencies of frame avoided the natural frequencies of main rotor, tail blade and engine and can meet the request of dynamic of unmanned helicopter. The dynamic analysis method based on finite element analyses, which combines verification test and modal modification, can effectively guarantee the accuracy of the fuselage frame of unmanned helicopter. And it also provides the refrence for finite element dynamic modeling about other structure of unmanned helicopter.%建立某无人直升机机身框架的动力学有限元模型,计算得到前六阶固有频率和振型,与模态试验结果相比较,误差小于3%,验证了有限元模型的正确性,表明该有限元模型能准确地反映该无人直升机框架的结构动力学特性.有限元计算的机身框架固有频率值避开了旋翼、尾桨、发动机主通过频率值,满足动力学设计要求.这种有限元计算、试验验证以及模型修改相结合的动力学分析方法,能保证框架固有特性计算的精确,也为无人直升机其它结构的动力学建模提供借鉴.

  8. The evolution of helicopters (United States)

    Chen, R.; Wen, C. Y.; Lorente, S.; Bejan, A.


    Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between body size, engine size, and the fuel load. Furthermore, the engine efficiency increases with the engine size, and the propeller radius is roughly the same as the length scale of the whole body. These trends are in accord with the constructal law, which accounts for the engine efficiency trend and the proportionality between "motor" size and body size in animals and vehicles. These body-size effects are qualitatively the same as those uncovered earlier for the evolution of aircraft. The present study adds to this theoretical body of research the evolutionary design of all technologies [A. Bejan, The Physics of Life: The Evolution of Everything (St. Martin's Press, New York, 2016)].

  9. Development and evaluation of a generic active helicopter vibration controller (United States)

    Davis, M. W.


    A computerized generic active controller is developed, which alleviates helicopter vibration by closed-loop implementation of higher harmonic control (HHC). In the system, the higher harmonic blade pitch is input through a standard helicopter swashplate; for a four-blade helicopter rotor the 4/rev vibration in the rotorcraft is minimized by inducing cyclic pitch motions at 3, 4, and 5/rev in the rotating system. The controller employs the deterministic, cautious, and dual control approaches and two linear system models (local and global), as well as several methods of limiting control. Based on model testing, performed at moderate to high values of forward velocity and rotor thrust, reductions in the rotor test apparatus vibration from 75 to 95 percent are predicted, with HHC pitch amplitudes of less than one degree. Good performance is also noted for short-duration maneuvers.

  10. Development of Filter-Blower Unit for use in the Advanced Nuclear Biological Chemical Protection System (ANBCPS) Helicopter/Transport-aircraft version

    NARCIS (Netherlands)

    Sabel, R.; Reffeltrath, P.A.; Jonkman, A.; Post, T.


    As a participant in the three-nation partnership for development of the ANBCP-S for use in Helicopters, Transport Aircraft and Fast Jet, the Royal Netherlands Airforce (RNLAF) picked up the challenge to design a Filter- Blower-Unit (FBU). Major Command (MajCom) of the RNLAF set priority to develop a

  11. Development of Filter-Blower Unit for use in the Advanced Nuclear Biological Chemical Protection System (ANBCPS) Helicopter/Transport-aircraft version

    NARCIS (Netherlands)

    Sabel, R.; Reffeltrath, P.A.; Jonkman, A.; Post, T.


    As a participant in the three-nation partnership for development of the ANBCP-S for use in Helicopters, Transport Aircraft and Fast Jet, the Royal Netherlands Airforce (RNLAF) picked up the challenge to design a Filter- Blower-Unit (FBU). Major Command (MajCom) of the RNLAF set priority to develop a

  12. Study to Determine the CB (Chemical/Biological) Threat and Define Alternative Crew Protection Systems for the Advanced Attack Helicopter (AAH). Volume 1 (United States)


    34Advlanced Attack Helicopter (AAH). This document should be of significant benefit to the AAH Project Management (AAM PM) for future planning and/or...position. The inner permeable five finger gloves are ambidextrous . Materials Used: The impermeable outer gloves are unsupported butyl rubber 0.6 -n (0.025

  13. Quad-Rotor Helicopter Autonomous Navigation Based on Vanishing Point Algorithm

    Directory of Open Access Journals (Sweden)

    Jialiang Wang


    Full Text Available Quad-rotor helicopter is becoming popular increasingly as they can well implement many flight missions in more challenging environments, with lower risk of damaging itself and its surroundings. They are employed in many applications, from military operations to civilian tasks. Quad-rotor helicopter autonomous navigation based on the vanishing point fast estimation (VPFE algorithm using clustering principle is implemented in this paper. For images collected by the camera of quad-rotor helicopter, the system executes the process of preprocessing of image, deleting noise interference, edge extracting using Canny operator, and extracting straight lines by randomized hough transformation (RHT method. Then system obtains the position of vanishing point and regards it as destination point and finally controls the autonomous navigation of the quad-rotor helicopter by continuous modification according to the calculated navigation error. The experimental results show that the quad-rotor helicopter can implement the destination navigation well in the indoor environment.

  14. Square tracking sensor for autonomous helicopter hover stabilization (United States)

    Oertel, Carl-Henrik


    Sensors for synthetic vision are needed to extend the mission profiles of helicopters. A special task for various applications is the autonomous position hold of a helicopter above a ground fixed or moving target. As a proof of concept for a general synthetic vision solution a restricted machine vision system, which is capable of locating and tracking a special target, was developed by the Institute of Flight Mechanics of Deutsche Forschungsanstalt fur Luft- und Raumfahrt e.V. (i.e., German Aerospace Research Establishment). This sensor, which is specialized to detect and track a square, was integrated in the fly-by-wire helicopter ATTHeS (i.e., Advanced Technology Testing Helicopter System). An existing model following controller for the forward flight condition was adapted for the hover and low speed requirements of the flight vehicle. The special target, a black square with a length of one meter, was mounted on top of a car. Flight tests demonstrated the automatic stabilization of the helicopter above the moving car by synthetic vision.

  15. Helicopter flights with night-vision goggles: Human factors aspects (United States)

    Brickner, Michael S.


    Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques.

  16. 用于电力线巡检的大型无人直升机多传感器系统集成设计%Integrated Design on Multi-sensor System of Large Unmanned Helicopter for Electric Power Inspection

    Institute of Scientific and Technical Information of China (English)

    王柯; 蔡艳辉; 彭向阳; 刘正军; 麦晓明; 张金铎


    基于电力线路安全巡检需要,设计了集可见光相机、红外热像仪、紫外成像仪、激光扫描仪和定位定姿系统等设备为一体的无人直升机多传感器系统。提出了基于全球定位系统时间系统的高精度后处理软同步方法,实现各个传感器系统的独立、协调同步工作。同时提出基于服务器–客户端软件架构,实现各个传感器控制和数据采集的相互独立,最大限度提高传感器系统工作的安全性和可靠性。多传感器集成的无人机巡检试验结果显示,该系统能够在单次飞行中同步获取多波段、多种类型的巡检数据,数据之间具有强相关性,可以用于多源数据联合诊断分析,满足电力线路安全隐患多要素自动诊断的需要。%Based on requirements for safe inspection on electric power lines,a kind of multi-sensor system of unmanned heli-copter which includes visible light camera,infrared imager,ultraviolet imager,laser scanner,positioning and orientation system (POS),and so on is designed. Meanwhile,a high-precision and post-process soft synchronization method based on global positioning system (GPS)is proposed for realizing independent,coordinate and synchronous work of each sensor sys-tem. Software structure based on server-customer is designed to realize mutual independence of each sensor control and data acquisition,and furthest improve security and reliability of the sensor system. Experimental results of inspection of the multi-sensor integrated unmanned helicopter indicate that this system could obtain multi-wave and polytype inspection data at the same time in one single flying,and there is strong correlation among data which could be used for united diagnosis and a-nalysis on multi-source data and satisfy requirement for automatic diagnosis on multi-factor in potential safe hazards of elec-tric power lines.

  17. Fault diagnostics system for helicopter main gearbox using wavelet neural network%基于小波神经网络的直升机主减速器故障诊断系统

    Institute of Scientific and Technical Information of China (English)

    刘立生; 杨宇航


    应用离散小波变换(DWT)和神经网络相结合构建直升机主减速器速器故障诊断系统:DWT对振动信号进行特征提取,神经网络对故障进行辨识和分类。阐述了DWT、帕塞瓦尔定理和广义回归神经网络(GRNN)基本理论,提出了直升机主减速器的故障诊断系统流程图,最后用某型直升机飞行时主减速器上的振动数据对该系统进行验证。实验使用了BPNN(back-propagation neural network)和GRNN两种神经网络,结果表明:提出的故障诊断系统能对主减速器故障进行较好的辨识和分类,这将为直升机主减速器故障诊断系统的进一步开发提供新的技术参考。%A fault diagnostics system for helicopter main gearbox (MGB) was construc- ted using discrete wavelet transform (DWT) and neural network, and the DWT was used to extract feature vectors and neural network was used for fault distinguish and classification. Firstly, the theory of DWT, Parseval theorem and GRNN were introduced, and then, the flowchart of fault diagnostics system for helicopter MGB was proposed, finally, the system was verified by the vibration data which were collected during helicopter flying, and both generalized regression neural network (GRNN) and back-propagation neural network (BPNN) were used and compared on the experimental platform. Experimental results indicate that the proposed diagnostics system can distinguish the MGB fault better, which would provide a new technical reference for the further development of helicopter MGB fault diagnostics system.

  18. Plan, formulate, discuss and correlate a NASTRAN finite element vibrations model of the Boeing Model 360 helicopter airframe (United States)

    Gabel, R.; Lang, P. F.; Smith, L. A.; Reed, D. A.


    Boeing Helicopter, together with other United States helicopter manufacturers, participated in a finite element applications program to emplace in the United States a superior capability to utilize finite element analysis models in support of helicopter airframe design. The activities relating to planning and creating a finite element vibrations model of the Boeing Model 36-0 composite airframe are summarized, along with the subsequent analytical correlation with ground shake test data.

  19. Integrated cockpit design for the Army helicopter improvement program (United States)

    Drennen, T.; Bowen, B.


    The main Army Helicopter Improvement Program (AHIP) mission is to navigate precisely, locate targets accurately, communicate their position to other battlefield elements, and to designate them for laser guided weapons. The onboard navigation and mast-mounted sight (MMS) avionics enable accurate tracking of current aircraft position and subsequent target location. The AHIP crewstation development was based on extensive mission/task analysis, function allocation, total system design, and test and verification. The avionics requirements to meet the mission was limited by the existing aircraft structural and performance characteristics and resultant space, weight, and power restrictions. These limitations and night operations requirement led to the use of night vision goggles. The combination of these requirements and limitations dictated an integrated control/display approach using multifunction displays and controls.

  20. Investigating Flight with a Toy Helicopter (United States)

    Liebl, Michael


    Flight fascinates people of all ages. Recent advances in battery technology have extended the capabilities of model airplanes and toy helicopters. For those who have never outgrown a childhood enthusiasm for the wonders of flight, it is possible to buy inexpensive, remotely controlled planes and helicopters. A toy helicopter offers an opportunity…

  1. Civil helicopter flight research. [for CH-53 helicopter (United States)

    Snyder, W. J.; Schoultz, M. B.


    The paper presents a description of the NASA CH-53 Civil Helicopter Research Aircraft and discusses preliminary results of the aircraft flight research performed to evaluate factors and requirements for future helicopter transport operations. The CH-53 equipped with a 16-seat airline-type cabin and instrumented for flight research studies in noise, vibration, handling qualities, passenger acceptance, fuel utilization, terminal area maneuvers, and gust response. Predicted fuel usage for typical short-haul missions is compared with actual fuel use. Pilot ratings for an IFR handling quality task for three levels of stability augmentation are presented, and the effects of internal noise, vibration, and motion on passenger acceptance are discussed. Future planned CH-53 flight research within the Civil Helicopter Technology Program is discussed.

  2. Helicopter air resonance modeling and suppression using active control (United States)

    Takahashi, M. D.; Friedmann, P. P.


    A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. Using this mathematical model, a nominal configuration is selected with an air resonance instability throughout most of its flight envelope. A multivariable compensator is then designed using two swashplate inputs and a single-body roll rate measurement. The controller design is based on the linear quadratic Gaussian technique and the loop transfer recovery method. The controller is shown to suppress the air resonance instability throughout a wide range of helicopter loading conditions and forward flight speeds.

  3. Helicopter blade-absorber system combination resonance research%直升机桨叶/吸振器系统的组合共振研究

    Institute of Scientific and Technical Information of China (English)

    周薇; 韩景龙


    应用 Lagrange 方程建立了直升机桨叶/吸振器系统的非线性振动模型,将一种规范型计算方法引入到桨叶/吸振器系统的组合共振研究,分析了该系统在发生组合共振时的稳定性和局部分岔特性。利用多尺度法求出系统平均方程,并对平均方程存在一对纯虚特征值与双零特征值的两类临界情形进行了研究,得到了系统的 Hopf 分岔解、分岔路径以及转迁曲线,给出了初始平衡解的稳定区域。对每一种情形,理论预测结果均与 Runge-Kutta 验证结果完全一致。%In the present paper,by using Lagrange equation,a nonlinear vibration model of helicopter blade-absorber system is established.The normal form method is introduced to the blade-absorber system for the combination resonance research,and through which,the stability and the local bifurcation characteristics of the blade-absorber system near combination resonance are analyzed.In order to derive the averaged equations,the method of multiple scales is applied,and then two kinds of critical points for the averaged equations are considered,which are characterized by a pair of purely imaginary eigenvalues and a pair of complex conjugate eigenvalues as well as a double zero eigenvalues.The Hopf bifurcation solution,bifurcation path,and tran-sition curves of the model are obtained respectively,and initial equilibrium stability region is given.For each case,the numeri-cal results obtained by Runge-Kutta method coincide with the analytical predictions.

  4. Rotor damping analysis based on helicopter dynamic requirement with rotor/fuselage coupling%基于耦合动力学要求的旋翼阻尼器特性分析

    Institute of Scientific and Technical Information of China (English)

    郭俊贤; 向锦武; 覃海鹰


    旋翼阻尼特性是直升机动力学问题的要素之一,根据全机动力学设计要求,进行地面共振和旋翼/动力/传动扭振系统稳定性分析,并据此提出旋翼系统阻尼特性参数设计要求.分析了粘弹性阻尼器和液压阻尼器的特点,研究了阻尼器刚度和阻尼对全机耦合动力学的影响;通过比较不同孔径节流孔的阻尼特性,确定了阻尼器设计方案.计算分析结果以及阻尼器样件的性能试验和机上试验验证结果表明:阻尼特性能够满足地面共振和旋翼/动力/传动扭振系统稳定性要求,并可实现其用于桨叶折叠的功能要求.%The rotor damping is one of the key points for a helicopter dynamic design. An introduction to the theoretical and practical study of one of the helicopter dynamic problems, which describesd the development of the rotor damping based on the helicopter dynamic with rotor/fuselage coupling that contains the stability analysis of ground resonance and the stability of rotor/power/transmission coherent was given. Based on the dynamic requirement of rotor/frame, damping analysis of the elasto-damper and the fluid-damper, which considered the effect of the stiffness and the damping was presented. The parametric sensitivity of the damper stiffness and damping was estimated. With constraints from engine control and ground resonance, the different effect was given with various available designs. Calculating and testing results performed demonstrating that, as solution to the dynamic problem, the damping with suitable orifice design for a variable liquid damper is reasonable for the helicopter dynamic problem solution and rotor blade folding.

  5. Assistance system for helicopter pilots in the starting and landing phase; Assistenzsystem zur Unterstuetzung von Hubschrauberpiloten bei An- und Abflug

    Energy Technology Data Exchange (ETDEWEB)

    Rataj, J.; Bender, K.; Kohrs, R. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Braunschweig (Germany). Inst. fuer Flugfuehrung


    Pilot assistance systems as a rule serve to support the pilot in a single task and are independent of each other and of other board systems. The task of connecting the information and bridging the information gap between the single systems remains with the pilot. The contribution presents a new system which combines existing and new support functions in a single system with a standardized man-machine interface. All data acquired are combined in a central data pool connected with a database to provide a central information system. The new system takes account of human behaviour patterns and thus improves the man-machine interactions. [German] Das vorgestellte Unterstuetzungssystem verbessert die Sicherheit und Effizienz sowie die Umweltvertraeglichkeit beim An- und Abflug von Hubschraubern in bekanntem Gelaende durch einen neuen Ansatz beim Entwurf von Mensch-Maschine-Systemen (MMS). Moderne Systeme zur Unterstuetzung von Piloten werden bislang fuer die Loesung einer einzelnen Flugaufgabe, wie z.B. Autopilot oder Flugbahnplanung, unabhaengig von dem jeweiligen Missionsabschnitt sowie der weiteren Systeme an Bord ausgelegt. Die daraus entstehenden Grenzen im Informationsfluss zwischen den Einzelsystemen sind bei dieser Art der Auslegung von den Piloten zu ueberwinden. Das in diesem Artikel vorgestellte Unterstuetzungssystem fasst vorhandene und neue Unterstuetzungsfunktionen in einem System mit einer einheitlichen Mensch-Maschine-Schnittstelle (HMI) zusammen und hebt damit die Grenzen zwischen den Einzelsystemen auf. Die Sammlung der an Bord vorhandenen Informationen im zentralen Datenpool und dessen Verknuepfung mit einer Datenbank bilden die Wissensbasis des Unterstuetzungssystems, das zentrale Informationssystem. Der neue Ansatz bei der Auslegung des Unterstuetzungssystems traegt dem menschlichen Verhalten der Operateure bei Fuehrungs- und Steuerungsaufgaben Rechnung, woraus eine deutlich verbesserte Aufgabenteilung und Kooperation zwischen Mensch und Maschine

  6. Analysis of Aerodynamic and Vibration Characteristics of a Micro Quad-rotor Helicopter with Low Reynolds Number%低雷诺数下微型四旋翼飞行器气动和振动特性分析

    Institute of Scientific and Technical Information of China (English)

    齐书浩; 刘素娟; 张文明; 肖心想


    基于有限元方法研究低雷诺数下微型四旋翼飞行器的气动特性和振动特性。建立微型四旋翼飞行器悬飞时的三维流场物理模型,给出边界条件,采用有限体积法对多个边界条件进行数值计算和分析,研究微型四旋翼飞行器在悬飞过程中的流场分布,揭示微型四旋翼飞行器的气动特性变化规律;此外,将气动载荷加载到结构分析模块,研究机身应力分布情况和流固耦合特性,得到机身最大应力所在位置及其振动特性。%Aerodynamic and vibration characteristics of a micro quad-rotor helicopter were studied based on finite element method. A three dimensional physical model of the flow field was established. By adding boundary conditions, the flow field was analyzed numerically using the finite volume method and its aerodynamic characteristics were obtained. Then the aerodynamic force was loaded to the helicopter structure to get the stress distribution and find out where the maximum stress occurs. Finally, the first six vibration modes and their vibration characteristics were obtained after the modal analysis of the micro quad-rotor helicopter.

  7. [Back ache in helicopter pilots]. (United States)

    Colak, S; Jovelić, S; Manojlović, J


    Due to low back pain (LBP) and harmful effects of flying, questionnaires were sent to 71 helicopter pilots of the experimental group, 22 mechanics helicopter flyers and to the control group of 28 air-traffic controllers. The prevalence of LBP was the highest in helicopter pilots, then in helicomechanics and air-traffic controllers (53%, 50% and 36%). Effects of exposure to vibration, body posture and working load have not contributed significantly to the occurrence of LBP. LBP has not lead to an important difference in the strength of the back musculature, body mass index and spondylosis, that is, scoliosis. The necessity of further study of LBP and maintaining of specific preventive measures are indicated.

  8. Magnetorheological fluids and applications to adaptive landing gear for a lightweight helicopter (United States)

    Ahure-Powell, Louise A.

    During hard landing or crash events of a helicopter there are impact loads that can be injurious to crew and other occupants as well as damaging to the helicopter structure. Landing gear systems are the first in line to protect crew and passengers from detrimental crash loads. The main focus of this research is to improve landing gear systems of a lightweight helicopter. Magnetorheological fluids (MRFs) provide potential solutions to several engineering challenges in a broad range of applications. One application that has been considered recently is the use of magnetorheological (MR) dampers in helicopter landing gear systems. In such application, the adaptive landing gear systems have to continuously adjust their stroking load in response to various operating conditions. In order to support this rotorcraft application, there is a necessity to validate that MRFs are qualified for landing gear applications. First, MRF composites, synthesized utilizing three hydraulic oils certified for use in landing gear systems, two average diameters of spherical magnetic particles, and a lecithin surfactant, are formulated to investigate their performance for potential use in a helicopter landing gear. The magnetorheology of these MR fluids is characterized through a range of tests, including (a) magnetorheology (yield stress and viscosity) as a function of magnetic field, (b) sedimentation analysis using an inductance-based sensor, (c) cycling of a small-scale MR damper undergoing sinusoidal excitations (at 2.5 and 5 Hz), and (d) impact testing of an MR damper for a range of magnetic field strengths and velocities using a free-flight drop tower facility. The performance of these MR fluids was analyzed, and their behavior was compared to standard commercial MR fluids. Based on this range of tests used to characterize the MR fluids synthesized, it was shown that it is feasible to utilize certified landing gear hydraulic oils as the carrier fluids to make suitable MR fluids

  9. 2.75 Inch Rocket/AH-1G Helicopter Weapons System Baseline Instrumentation Test Report. Volume 1, (United States)


    network with sharper transduers while eliminating the e a d cost eut-of characteristics than thoe ordinarily supplied of complex arrier systems...chancX in the output proportional to the displacement. Both IF LOAD series of transduers are available in seven stroke W.e s rn .Cores ane available with

  10. Integrated Multivariate Health Monitoring System for Helicopters Main Rotor Drives: Development and Validation with In-Service Data (United States)


    distribution of the ordinary regime of the process. In a population characterised by a multidimensional Gauss distribution, the Mahalanobis distances...The extent to which the filtered healthy operational states of each component of the power drive fit with a multidimen- sional Gauss distribution...automotive and aerospace applications. John Wiley and Sons, Ltd. Publications. Rencher, A. C. (2002). Methods of multivariate analysis. Wi- ley

  11. 77 FR 30232 - Airworthiness Directives; Bell Helicopter Textron Helicopters (United States)


    ... Textron (BHT) Model 412, 412EP, and 412CF helicopters. This proposed AD is prompted by a reported failure... delay. We may change this proposal in light of the comments we receive. Discussion BHT has received a... develop on other products of the same type design. Related Service Information We reviewed BHT ASB 412-11...

  12. 77 FR 68055 - Airworthiness Directives; Bell Helicopter Textron Helicopters (United States)


    ... are adopting a new airworthiness directive (AD) for Bell Helicopter Textron (BHT) Model 412, 412EP... 39 to include an AD that would apply to certain serial-numbered BHT Model 412, 412EP, and 412CF... AD and the Service Information The BHT ASBs require compliance within 100 hours of flight time for...

  13. 78 FR 9793 - Airworthiness Directives; Bell Helicopter Textron Helicopters (United States)


    ..., Aerospace Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 2601 Meacham Blvd., Fort... helicopters, are susceptible to the same type of cracking because they are of similar design and manufacture... first. This AD does not require you to report a cracked fitting to the Rotorcraft Certification...

  14. 78 FR 1730 - Airworthiness Directives; Bell Helicopter Textron Inc. Helicopters (United States)


    ...: We are adopting a new airworthiness directive (AD) for the Bell Helicopter Textron Inc. (BHTI) Model... (connector) can deteriorate, causing a short in the connector that may lead to a fire in the starter... short in the connector that may lead to a fire in the starter/generator, smoke in the cockpit...

  15. 78 FR 65195 - Airworthiness Directives; MD Helicopters, Inc. (MDHI) Helicopters (United States)


    ... other helicopters of the same type designs and that air safety and the public interest require adopting... rotor blade (MRB) retention bolts (bolts) installed. This AD requires a daily check of the position of... (ASB SB900-116). ASB SB900-116 specifies a repetitive check of the blade retention bolts, part number...

  16. Aeroelastic analysis for helicopter rotors with blade appended pendulum vibration absorbers. Mathematical derivations and program user's manual (United States)

    Bielawa, R. L.


    Mathematical development is presented for the expanded capabilities of the United Technologies Research Center (UTRC) G400 Rotor Aeroelastic Analysis. This expanded analysis, G400PA, simulates the dynamics of teetered rotors, blade pendulum vibration absorbers and the higher harmonic excitations resulting from prescribed vibratory hub motions and higher harmonic blade pitch control. Formulations are also presented for calculating the rotor impedance matrix appropriate to these higher harmonic blade excitations. This impedance matrix and the associated vibratory hub loads are intended as the rotor blade characteristics elements for use in the Simplified Coupled Rotor/Fuselage Vibration Analysis (SIMVIB). Sections are included presenting updates to the development of the original G400 theory, and material appropriate to the user of the G400PA computer program. This material includes: (1) a general descriptionof the tructuring of the G400PA FORTRAN coding, (2) a detaild description of the required input data and other useful information for successfully running the program, and (3) a detailed description of the output results.

  17. 78 FR 17591 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters (United States)


    ... elements with 10 micron fuel filter elements at the next scheduled inspection or within 150 flight hours... identification plate, cross out the last two digits (``09'') of the ] existing fuel filter P/N 52-2145-009, and... helicopters to require replacing each forward and aft fuel system 40 micron fuel filter element with a...

  18. Helicopter parameter extraction using joint Time-Frequency and Tomographic Techniques

    CSIR Research Space (South Africa)

    Cilliers, A


    Full Text Available A technique based on time-frequency and tomographic analysis to extract helicopter blade parameters for the purposes of radar non-cooperative target recognition (NCTR) is investigated. The proposed algorithm shows that (under certain conditions...

  19. Helicopter collision avoidance and brown-out recovery with HELLAS (United States)

    Seidel, Christian; Schwartz, Ingo; Kielhorn, Peter


    EADS Germany is the world market leader in commercial and military Helicopter Laser Radar (HELLAS) Obstacle Warning Systems. The HELLAS-Warning System has been introduced into the market in 2000, is in service at German Federal Police and Royal Thai Air Force. HELLAS was also successfully evaluated by the Foreign Comparative Test Program (FCT) of the U.S. Army and other governmental agencies. Currently the successor system for military applications, HELLAS-Awareness, is in qualification phase. It will have extended sensor performance, enhanced real-time data processing capabilities and advanced human machine interface (HMI) features. Flight tests on NH90 helicopter have been successfully performed. Helicopter series integration is scheduled to begin from 2009. We will give an outline of the new sensor unit concerning detection technology and helicopter integration aspects. The system provides a widespread field of view with additional dynamic line of sight steering and a large detection range in combination with a high frame rate. We will show the HMI representations. This HELLAS system is the basis for a 3 dimensional see-and-remember-system for brown-out recovery. When landing in sandy or dusty areas the downwash of the helicopter rotor causes clouds of visually-restrictive material that can completely obstruct the pilot's outside reference, resulting in a complete loss of situational awareness and spatial orientation of the pilot which can end up in total loss of aircraft control and dangerous accidents. The brown-out recovery system presented here creates an augmented enhanced synthetic vision of the landing area with the surrounding which is based on HELLAS range image data as well as altimeter and inertial reference information.

  20. 某无人直升机复杂系统动力学建模及试验验证%Test and Research on Complicated Structure Modeling Techniques of Vibration Analysis for an Unmanned Helicopter

    Institute of Scientific and Technical Information of China (English)

    张志清; 姜年朝; 李湘萍; 周光明; 张逊; 戴勇


    The structure of an unmanned helicopter has been studicd, which is complicated and hard to be modeling. The modeling strategies,which divide whole helicopter into main frame,landing gear, tail boom pipe, tail boom tube. and empennage, and perform the study of finite model ing, dynamic test. test - analysis correlation, and model improvement techniques respectively, is employed. On base of that, the improved component models are installed together into whole dynamic model by modeling the intersections among the components.%以某无人直升机复杂结构为研究对象,分别建立主框架、起落架、尾管、尾撑和垂平尾等组件的有限元模型;通过试验,修正各部件的有限元模型,运用MPC技术构建了全机复杂结构的动力学分析模型,最后进行了试验验证.

  1. 变位齿轮在直升机传动系统中的应用研究%Application of Profile Shifted Gear in the Helicopter Transmission System

    Institute of Scientific and Technical Information of China (English)

    李英明; 沙发明; 黄康; 陈奇; 赵韩


    In order to study profile shifted gear in the helicopter transmission system,a pair of large ratio helicopter gear is studied.The influence of modification coefficient on gear tooth root sliding rate and contact ratio is studied,and the variation of profile shifted gear and master gear contact stress,bending stress is discussed.The results show that modification treatment can make the root sliding coefficient close,while the influence on contact ratio is small,the gear contact stress and bending stress are reduced.%为了研究变位齿轮在直升机传动系统中的应用,以一对大传动比的直升机齿轮对为例,研究变位系数对齿轮的齿根滑动系数和重合度的影响,并讨论变位和非变位齿轮的接触应力、弯曲应力变化情况.结果表明,变位处理可以使齿根滑动系数接近,同时对重合度影响较小,降低了齿轮的接触应力和弯曲应力.

  2. Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction (United States)

    Shin, SangJoon; Cesnik, Carlos E. S.


    Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration

  3. Smart actuation for helicopter rotorblades

    NARCIS (Netherlands)

    Paternoster, A.R.A.; Loendersloot, R.; Boer, de A.; Akkerman, R.; Berselli, G.; Vertechy, R.; Vassura, G.


    Successful rotorcrafts were only achieved when the differences between hovering flight conditions and a stable forward flight were understood. During hovering, the air speed on all helicopter blades is linearly distributed along each blade and is the same for each. However, during forward flight, th

  4. Helicopter Toy and Lift Estimation (United States)

    Shakerin, Said


    A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

  5. Helicopter Toy and Lift Estimation (United States)

    Shakerin, Said


    A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

  6. Smart actuation for helicopter rotorblades

    NARCIS (Netherlands)

    Paternoster, Alexandre; Loendersloot, Richard; de Boer, Andries; Akkerman, Remko; Berselli, G.; Vertechy, R.; Vassura, G.


    Successful rotorcrafts were only achieved when the differences between hovering flight conditions and a stable forward flight were understood. During hovering, the air speed on all helicopter blades is linearly distributed along each blade and is the same for each. However, during forward flight,

  7. Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model

    DEFF Research Database (Denmark)

    Lee, Hyun-Ku; Viswamurthy, S.R.; Park, Sang Chul


    rotor-blade/control-system model was loosely coupled with various inflow and wake models in order to simulate both hover and forward-flight conditions. The resulting rotor blade response and pitch link loads are in good agreement with those predicted byCAMRADII. The present analysis features both model......In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based...... on an intrinsic formulation of moving beams implemented in the time domain. The rotor control system was modeled as a combination of rigid and elastic components. A multicomponent analysis was then developed by coupling the beam finite element model with the rotor control system model to obtain a complete rotor-blade/control...

  8. A Hybrid Flight Control for a Simulated Raptor-30 V2 Helicopter

    Directory of Open Access Journals (Sweden)

    Arbab Nighat Khizer


    Full Text Available This paper presents a hybrid flight control system for a single rotor simulated Raptor-30 V2 helicopter. Hybrid intelligent control system, combination of the conventional and intelligent control methodologies, is applied to small model helicopter. The proposed hybrid control used PID as a traditional control and fuzzy as an intelligent control so as to take the maximum advantage of advanced control theory. The helicopter?s model used; comes from X-Plane flight simulator and their hybrid flight control system was simulated using MATLAB/SIMULINK in a simulation platform. X-Plane is also used to visualize the performance of this proposed autopilot design. Through a series of numerous experiments, the operation of hybrid control system was investigated. Results verified that the proposed hybrid control has an excellent performance at hovering flight mode.

  9. Nine Years of Cooperation: The US-German Memorandum of Understanding (MoU) on Helicopter Aeromechanics 2003-2012 (United States)


    major source of structural loads of the rotor blades and the pitch links, as well a major source of vibrations and fatigue. Objectives: The...Extreme operation conditions on rotor blades limit the helicopter in many respects, like maximum speed, efficiency, noise emissions, and loading ...individuals contributed to the modern helicopter handling quality requirements with theoretical analysis, piloted simulations, and flight tests. The

  10. Ground vibration tests of a helicopter structure using OMA techniques (United States)

    Ameri, N.; Grappasonni, C.; Coppotelli, G.; Ewins, D. J.


    This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on helicopter structures. For this purpose, a ground vibration test was performed on a real helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input-output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The structure considered is a medium-size helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.

  11. Some thoughts on the implementation of pilot night vision devices for helicopters (United States)

    Tucker, G. E.


    Night vision enhancement devices greatly expand the range and quality of services by extending night operational capabilities. Evolving military tactical concepts for helicopters survivability and battlefield effectiveness necessitate nap-of-the-earth (NOE) flying under both day and night conditions. From a pilot workload standpoint, flying a helicopter NOE in day VFR conditions with minimum clearance between rotors and obstacles is quite demanding. Doing the same job at night is several times more difficult. There are two general categories of night vision devices in operation in helicopter aviation: the Night Vision Goggles (NVG) and forward looking infrared (FLIR) system. The capabilities and limitations of those two devices are discussed.

  12. Applications of numerical optimization methods to helicopter design problems - A survey (United States)

    Miura, H.


    A survey of applications of mathematical programming methods is used to improve the design of helicopters and their components. Applications of multivariable search techniques in the finite dimensional space are considered. Five categories of helicopter design problems are considered: (1) conceptual and preliminary design, (2) rotor-system design, (3) airframe structures design, (4) control system design, and (5) flight trajectory planning. Key technical progress in numerical optimization methods relevant to rotorcraft applications are summarized.

  13. Applications of numerical optimization methods to helicopter design problems: A survey (United States)

    Miura, H.


    A survey of applications of mathematical programming methods is used to improve the design of helicopters and their components. Applications of multivariable search techniques in the finite dimensional space are considered. Five categories of helicopter design problems are considered: (1) conceptual and preliminary design, (2) rotor-system design, (3) airframe structures design, (4) control system design, and (5) flight trajectory planning. Key technical progress in numerical optimization methods relevant to rotorcraft applications are summarized.

  14. Analysis of backleg pain in fighter and helicopter pilot%歼击机与直升机飞行人员腰腿痛的分析

    Institute of Scientific and Technical Information of China (English)

    刘永平; 陈宏; 汪红荣


    目的:了解歼击机与直升机飞行人员腰腿痛情况,有针对性地预防腰腿痛的发生。方法调查689例飞行人员的资料,比较分析歼击机与直升机飞行人员腰腿痛的情况。结果直升机飞行员腰腿痛的发生率为44.2%,歼击机飞行员腰腿痛的发生率为29.9%,直升机飞行员腰腿痛的发生率明显高于歼击机飞行员(P<0.05)。结论应重视飞行人员腰腿痛的预防,加强宣传教育,加强腰肌功能训练,加强防护措施。%Objective To investigate the morbidity and risk factors of backleg pain among fighter and helicopter pilots and to prevent the morbidity of backleg pain.Methods Through examining information of 689 fighter pilots,the morbidity and risk factors of backleg pain among fighter and helicopter pilots were analyzed.Results The morbidity rate of backleg pain among helicopter pilots was 44.2%.The morbidity rate of backleg pain among fighter pilots was 29.9%.The morbidity rate of backleg pain among helicoper pilots was higher than the morbidity rate among fighter pilots( P<0.05) .Conclusion Pay attention to importance to prevent backleg pain among pilots.We must emphasis propaganda,education,psoas training and research about protective device.

  15. Transmission error and load distribution analysis of spur and double helical gear pairs used in a split path helicopter transmission design (United States)

    Hochmann, David; Houser, Donald R.; Thomas, Jacob


    Because the reduction of gear noise in next-generation rotorcraft depends on the reduction of transmission errors, attention is presently given to the prediction of such errors and the load distributions of both a spur-gear pair and a double helical gear train used in a split-path helicopter transmission. Two cases are examined: (1) the spur gear mesh between the spur shaft and the lower spur/helical shaft, and (2) the double helical gear mesh between the lower spur/helical shaft and the output bull bear shaft.

  16. Compound cycle engine for helicopter application (United States)

    Castor, Jere; Martin, John; Bradley, Curtiss


    The compound cycle engine (CCE) is a highly turbocharged, power-compounded, ultra-high-power-density, lightweight diesel engine. The turbomachinery is similar to a moderate-pressure-ratio, free-power-turbine gas turbine engine and the diesel core is high speed and a low compression ratio. This engine is considered a potential candidate for future military helicopter applications. Cycle thermodynamic specific fuel consumption (SFC) and engine weight analyses performed to establish general engine operating parameters and configurations are presented. An extensive performance and weight analysis based on a typical 2-hour helicopter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a contemporary gas turbine engine. The CCE had a 31 percent lower-fuel consumption and resulted in a 16 percent reduction in engine plus fuel and fuel tank weight. Design SFC of the CCE is 0.33 lb/hp-hr and installed wet weight is 0.43 lb/hp. The major technology development areas required for the CCE are identified and briefly discussed.

  17. 78 FR 34958 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell), Model Helicopters (United States)


    ... 412CF helicopter or on a Model 412 or 412EP helicopter with a (BHT-412-SI-62) slope landing kit, P/N 412... installed on a Model 412 or 412EP helicopter with a (BHT-412-SI-62) slope landing kit, P/N 412-704-012-101...

  18. 78 FR 23688 - Airworthiness Directives; Bell Helicopter Textron Canada Inc. Helicopters (United States)


    ... Bell Helicopter Textron Canada Inc. (BHT) Model 206A, 206B, and 206L helicopters. This proposed AD...-2012-19), to correct an unsafe condition for certain serial numbered BHT Model 206A, 206B, and 206L... Information BHT has issued Alert Service Bulletin (ASB) No. 206-11-127 for Model 206A and 206B helicopters and...

  19. 78 FR 54751 - Airworthiness Directives; Bell Helicopter Textron Canada Inc. Helicopters (United States)


    ... new airworthiness directive (AD) for certain Bell Helicopter Textron Canada Inc. (BHT) Model 206A... 14 CFR part 39 to include an AD that would apply to BHT Model 206A and 206B helicopters, all serial... assembly) part number (P/N) 206-375-017-101 installed and BHT Model 206L helicopters, S/N 45001 through...

  20. Fabricated Helicopter Transmission Housing Analysis (United States)


    This program was conducted for the Military Operations Technology Division under the technical management of Hr. L. Thomas Mazza, Technology Applications...Data Xritred) Uncl ssified .UIJRITY -’.ASSIFICA ’.Wi OF THIS PAGE(Wen Date Entered) materials, analytical methods, and fabrication tecniques . The

  1. A real-time algorithm for integrating differential satellite and inertial navigation information during helicopter approach. M.S. Thesis (United States)

    Hoang, TY


    A real-time, high-rate precision navigation Kalman filter algorithm is developed and analyzed. This Navigation algorithm blends various navigation data collected during terminal area approach of an instrumented helicopter. Navigation data collected include helicopter position and velocity from a global position system in differential mode (DGPS) as well as helicopter velocity and attitude from an inertial navigation system (INS). The goal of the Navigation algorithm is to increase the DGPS accuracy while producing navigational data at the 64 Hertz INS update rate. It is important to note that while the data was post flight processed, the Navigation algorithm was designed for real-time analysis. The design of the Navigation algorithm resulted in a nine-state Kalman filter. The Kalman filter's state matrix contains position, velocity, and velocity bias components. The filter updates positional readings with DGPS position, INS velocity, and velocity bias information. In addition, the filter incorporates a sporadic data rejection scheme. This relatively simple model met and exceeded the ten meter absolute positional requirement. The Navigation algorithm results were compared with truth data derived from a laser tracker. The helicopter flight profile included terminal glideslope angles of 3, 6, and 9 degrees. Two flight segments extracted during each terminal approach were used to evaluate the Navigation algorithm. The first segment recorded small dynamic maneuver in the lateral plane while motion in the vertical plane was recorded by the second segment. The longitudinal, lateral, and vertical averaged positional accuracies for all three glideslope approaches are as follows (mean plus or minus two standard deviations in meters): longitudinal (-0.03 plus or minus 1.41), lateral (-1.29 plus or minus 2.36), and vertical (-0.76 plus or minus 2.05).

  2. Fully controlled helicopter for 3D-reconstruction of buildings and survey applications (United States)

    Lehmann, Raimund; Staiger, Stefan; Schröder, Werner


    At the Hochschule Offenburg, a fully controlled helicopter has been developed, which is very easy to fly by anybody and can be flown very close to objects. The flight control system consists of an attitude and heading reference system, an inertial navigator augmented by GPS and a flight control computer. The electrically driven helicopter can easily carry payloads of more than 1 kg. With this helicopter high resolution pictures were taken from parts of the Freiburg cathedral. Also pictures with a calibrated camera of terrain have been taken. Pictures were paired and using a commercial software, a 3D-model of a part of the top of the "Hahnenturm" of the Freiburg cathedral has been generated. The terrain pictures have been bundled and used to precisely measure the position of certain objects in the terrain. The first results of these trials are very promising in respect to future applications of the helicopter.

  3. Identification of helicopter rotor dynamic models (United States)

    Molusis, J. A.; Bar-Shalom, Y.; Warmbrodt, W.


    A recursive, extended Kalman-filter approach is applied to the identifiction of rotor damping levels of representative helicopter dynamic systems. The general formulation of the approach is presented in the context of a typically posed stochastic estimation problem, and the method is analytically applied to determining the damping levels of a coupled rotor-body system. The identified damping covergence characteristics are studied for sensitivity to both constant-coefficient and periodic-coefficient measurement models, process-noise covariance levels, and specified initial estimates of the rotor-system damping. A second application of the method to identifying the plant model for a highly damped, isolated flapping blade with a constant-coefficient state model (hover) and a periodic-coefficient state model (forward flight) is also investigated. The parameter-identification capability is evaluated for the effect of periodicity on the plant model coefficients and the influence of different measurement noise levels.

  4. Identification and stochastic control of helicopter dynamic modes (United States)

    Molusis, J. A.; Bar-Shalom, Y.


    A general treatment of parameter identification and stochastic control for use on helicopter dynamic systems is presented. Rotor dynamic models, including specific applications to rotor blade flapping and the helicopter ground resonance problem are emphasized. Dynamic systems which are governed by periodic coefficients as well as constant coefficient models are addressed. The dynamic systems are modeled by linear state variable equations which are used in the identification and stochastic control formulation. The pure identification problem as well as the stochastic control problem which includes combined identification and control for dynamic systems is addressed. The stochastic control problem includes the effect of parameter uncertainty on the solution and the concept of learning and how this is affected by the control's duel effect. The identification formulation requires algorithms suitable for on line use and thus recursive identification algorithms are considered. The applications presented use the recursive extended kalman filter for parameter identification which has excellent convergence for systems without process noise.

  5. Lytic spondylolisthesis in helicopter pilots. (United States)

    Froom, P; Froom, J; Van Dyk, D; Caine, Y; Ribak, J; Margaliot, S; Floman, Y


    Trauma to the back from the force of chronic stress is thought to be an etiologic factor in isthmic spondylolisthesis (SLL). The relationship of first degree spondylolisthesis to low back pain (LBP) is controversial. We compare the prevalence of SLL in helicopter pilots who are subject to strong vibrational forces, with other airforce personnel. Helicopter pilots had more than a four times higher prevalence of SLL (4.5%) than did cadets (1.0%) and transport pilots (0.9%). Low back pain was more frequent in pilots with SLL than in those without this lesion but in no case was the pain disabling or the defect progressive. We conclude that SLL may be induced by vibrational forces and although SLL is associated with LBP, the pain was little clinical significance.

  6. Critical Technology Events in the Development of the Apache Helicopter. Project Hindsight Revisited (United States)


    weapons systems also benefited the Apache. Among these advances were a common module approach to FLIR production and a minimum resolvable temperature ( MRT ...determination as a way to measure FLIR performance. Also, it should be noted that for the Apache, with the work on the MRT as a foundation, the U.S...Industry’s creative work on the T700 series of helicopter engines is an example. 3. The Army experiences with helicopters in Vietnam had a strong

  7. Final assessment of vibro-acoustic source strength descriptors of helicopter gearboxes

    DEFF Research Database (Denmark)

    Ohlrich, Mogens; Rasmussen, Ulrik Møller


    Two novel measurement techniques have been developed for quantifying the vibro-aqcoustic source strength of lightweight helicopter gearboxes. The accuracy, robustness and implementation of these methods have been examined by a comprehensive investigation, including theoretical studies of simple...... multi-modal beam systems and extensive experiments with more realistic small scale models and with large, detailed 3/4-scale test structures of a medium-size helicopter. In addition, partial verification tests have been conducted with the Eurocopter BK 117 helicopter and its main rotor gearbox....... The results of this work are essential as input for any prediction code of the internal noise in a helicopter cabin, because the prediction requires knowledge of the major sources, that is, the rotors, engines and gearboxes....

  8. Simulation and Analysis of Unmanned Helicopter Gyro Vibration%无人直升机陀螺减振的仿真与分析

    Institute of Scientific and Technical Information of China (English)

    朱文来; 葛峰


    The structure and principle of the gyro vibration are described, by using the finite ele-ment method,the damping effect of unmanned helicopter gyro vibration is studied. By analyzing,the can-tilever size of gyro damping structure is an important factor to affect the damping properties. That provides an effective analyzing method for subsequent mechanical structure vibration study.%简述了陀螺减振结构与原理,通过采用有限元方法对无人直升机陀螺减振结构的减振效果进行了仿真研究,经分析陀螺减振结构的悬臂尺寸是影响减振性能的重要因素,为后续机械结构振动研究提供了一种有效的分析方法。

  9. A new approach to helicopter rotor blade research instrumentation (United States)

    Knight, V. H., Jr.


    A rotor-blade-mounted telemetry instrumentation system developed and used in flight tests by the NASA/Langley Research Center is described. The system uses high-speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested using an AH-1G helicopter. The system employs microelectronic PCM multiplexer-digitizer stations located remotely on the blade and in a hub-mounted metal canister. The electronics contained in the canister digitizes up to 16 sensors, formats this data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data is transmitted over an RF link to the ground for real-time monitoring and to the helicopter fuselage for tape recording.

  10. Refinement and evaluation of helicopter real-time self-adaptive active vibration controller algorithms (United States)

    Davis, M. W.


    A Real-Time Self-Adaptive (RTSA) active vibration controller was used as the framework in developing a computer program for a generic controller that can be used to alleviate helicopter vibration. Based upon on-line identification of system parameters, the generic controller minimizes vibration in the fuselage by closed-loop implementation of higher harmonic control in the main rotor system. The new generic controller incorporates a set of improved algorithms that gives the capability to readily define many different configurations by selecting one of three different controller types (deterministic, cautious, and dual), one of two linear system models (local and global), and one or more of several methods of applying limits on control inputs (external and/or internal limits on higher harmonic pitch amplitude and rate). A helicopter rotor simulation analysis was used to evaluate the algorithms associated with the alternative controller types as applied to the four-bladed H-34 rotor mounted on the NASA Ames Rotor Test Apparatus (RTA) which represents the fuselage. After proper tuning all three controllers provide more effective vibration reduction and converge more quickly and smoothly with smaller control inputs than the initial RTSA controller (deterministic with external pitch-rate limiting). It is demonstrated that internal limiting of the control inputs a significantly improves the overall performance of the deterministic controller.


    Institute of Scientific and Technical Information of China (English)

    董凌华; 杨卫东; 夏品奇


    The multi-body analysis of the aeroelastic stability of the tiltrotor aircraft is presented. Multi-body dynamic differential equations are combined with the equations of the unsteady dynamic inflow model to establish the complete unsteadily aeroelastic coupling analytical model of the tiltrotor. The stability of the tiltrotor in the helicopter mode is analyzed aiming at a semi-span soft-inplane tiltrotor model with an elastic wing. Parametric effects of the lag stiffness of blades and the flight speed are analyzed. Numerical simulations demonstrate that the multi-body analytical model can analyze the aeroelastic stability of the tiltrotor aircraft in the helicopter mode.%通过多体动力学方法建立了倾转旋翼机动力学分析模型.结合动力入流,研究了直升机模式下倾转旋翼机非线性非定常气弹耦合动力学特性.集成了非定常动态入流方程与倾转过渡状态的多体动力学方程,建立了倾转旋翼机时域非定常气弹耦合分析模型.以半展长弹性机翼全铰接式倾转旋翼机模型为例,在直升机模式下分析了桨叶摆振刚度及飞行速度对倾转旋翼机气弹稳定性的影响.数值计算表明:建立的多体动力学模型能够快速分析直升机模式下倾转旋翼机复杂的旋翼/机翼气弹耦合动力学特性.

  12. Pneumatic boot for helicopter rotor deicing (United States)

    Blaha, B. J.; Evanich, P. L.


    Pneumatic deicer boots for helicopter rotor blades were tested. The tests were conducted in the 6 by 9 ft icing research tunnel on a stationary section of a UH-IH helicopter main rotor blade. The boots were effective in removing ice and in reducing aerodynamic drag due to ice.

  13. Flight test results of the fuzzy logic adaptive controller-helicopter (FLAC-H) (United States)

    Wade, Robert L.; Walker, Gregory W.


    The fuzzy logic adaptive controller for helicopters (FLAC-H) demonstration is a cooperative effort between the US Army Simulation, Training, and Instrumentation Command (STRICOM), the US Army Aviation and Troop Command, and the US Army Missile Command to demonstrate a low-cost drone control system for both full-scale and sub-scale helicopters. FLAC-H was demonstrated on one of STRICOM's fleet of full-scale rotary-winged target drones. FLAC-H exploits fuzzy logic in its flight control system to provide a robust solution to the control of the helicopter's dynamic, nonlinear system. Straight forward, common sense fuzzy rules governing helicopter flight are processed instead of complex mathematical models. This has resulted in a simplified solution to the complexities of helicopter flight. Incorporation of fuzzy logic reduced the cost of development and should also reduce the cost of maintenance of the system. An adaptive algorithm allows the FLAC-H to 'learn' how to fly the helicopter, enabling the control system to adjust to varying helicopter configurations. The adaptive algorithm, based on genetic algorithms, alters the fuzzy rules and their related sets to improve the performance characteristics of the system. This learning allows FLAC-H to automatically be integrated into a new airframe, reducing the development costs associated with altering a control system for a new or heavily modified aircraft. Successful flight tests of the FLAC-H on a UH-1H target drone were completed in September 1994 at the White Sands Missile Range in New Mexico. This paper discuses the objective of the system, its design, and performance.

  14. 78 FR 23692 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... in excessive vibration of the helicopter and loss of control of the helicopter. (c) Comments Due Date... Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM... AS350B, BA, B1, B2, B3, and D, and Model AS355E, F, F1, F2, and N helicopters with certain tail rotor...

  15. Helicopter Noise And Noise Abatement Procedures

    Directory of Open Access Journals (Sweden)

    Borivoj Galović


    Full Text Available The helicopter generated noise at and around the airports islower than the noise generated by aeroplanes, since their numberof operations, i. e. the number of takeoffs and landings ismuch lower than the takeoffs and landings of the aeroplanes.Out of some hundred operations a day, helicopters participatewith approximately 15%, but the very impact of noise is by nomeans negligible, since the number of helicopter flights aboveurban areas is constantly increasing.This paper attempts to analyse this phenomenon and thetype of helicopter generated noise, its negative impacts, to explainthe flight procedures and the operative procedures duringtakeoff, landing and overflight of helicopters in operations inthe vicinity and outside airports, as well as the methods of measuringand determining the limit of noise [eve~ and the resultingproblems.

  16. Heli/SITAN: A Terrain Referenced Navigation algorithm for helicopters

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, J.


    Heli/SITAN is a Terrain Referenced Navigation (TRN) algorithm that utilizes radar altimeter ground clearance measurements in combination with a conventional navigation system and a stored digital terrain elevation map to accurately estimate a helicopter's position. Multiple Model Adaptive Estimation (MMAE) techniques are employed using a bank of single state Kalman filters to ensure that reliable position estimates are obtained even in the face of large initial position errors. A real-time implementation of the algorithm was tested aboard a US Army UH-1 helicopter equipped with a Singer-Kearfott Doppler Velocity Sensor (DVS) and a Litton LR-80 strapdown Attitude and Heading Reference System (AHRS). The median radial error of the position fixes provided in real-time by this implementation was less than 50 m for a variety of mission profiles. 6 refs., 7 figs.

  17. Specific exercise training for reducing neck and shoulder pain among military helicopter pilots and crew members

    DEFF Research Database (Denmark)

    Murray, Mike; Lange, Britt; Nørnberg, Bo Riebeling


    BACKGROUND: Flight-related neck/shoulder pain is frequent among military helicopter pilots and crew members. With a lifetime prevalence of 81 % for pilots and 84 % for crew members, the prevalence of neck pain is considered high compared to the general population. The aim of this study was to inv......BACKGROUND: Flight-related neck/shoulder pain is frequent among military helicopter pilots and crew members. With a lifetime prevalence of 81 % for pilots and 84 % for crew members, the prevalence of neck pain is considered high compared to the general population. The aim of this study...... was to investigate whether a specifically tailored exercise intervention would reduce the prevalence and incidence rate of neck/shoulder pain among helicopter pilots and crew members. METHOD: This study used a prospective, parallel group, single blinded, randomized controlled design. Participants were military...... helicopter pilots and crew members recruited from the Royal Danish Air Force. Inclusion criteria were: 1) employed within the Royal Danish Air Force as a helicopter pilot or onboard crew member (technician, systems-operator, tactical helicopter observer and/or navigator), 2) maintaining operational flight...

  18. Systems Analysis of NASA Aviation Safety Program: Final Report (United States)

    Jones, Sharon M.; Reveley, Mary S.; Withrow, Colleen A.; Evans, Joni K.; Barr, Lawrence; Leone, Karen


    A three-month study (February to April 2010) of the NASA Aviation Safety (AvSafe) program was conducted. This study comprised three components: (1) a statistical analysis of currently available civilian subsonic aircraft data from the National Transportation Safety Board (NTSB), the Federal Aviation Administration (FAA), and the Aviation Safety Information Analysis and Sharing (ASIAS) system to identify any significant or overlooked aviation safety issues; (2) a high-level qualitative identification of future safety risks, with an assessment of the potential impact of the NASA AvSafe research on the National Airspace System (NAS) based on these risks; and (3) a detailed, top-down analysis of the NASA AvSafe program using an established and peer-reviewed systems analysis methodology. The statistical analysis identified the top aviation "tall poles" based on NTSB accident and FAA incident data from 1997 to 2006. A separate examination of medical helicopter accidents in the United States was also conducted. Multiple external sources were used to develop a compilation of ten "tall poles" in future safety issues/risks. The top-down analysis of the AvSafe was conducted by using a modification of the Gibson methodology. Of the 17 challenging safety issues that were identified, 11 were directly addressed by the AvSafe program research portfolio.

  19. [Causes of fatigue in civil aviation helicopter crews]. (United States)

    Kamenskiĭ, Iu N


    Vibration and noise play an important part in fatiguing crewmembers of helicopters. The exposure to these factors during the flying shift results in an early and marked fatigue of pilots the level of which depends on the vibration effects to a larger extent than on the noise effects. The fatigue is followed by a decline of the psychophysiological parameters characterizing the visual and motor functions as well as the ratio of the basic processes in the central nervous system.

  20. Enterprise Systems Analysis (United States)


    is unavailable until a remediation process fixes the contamination problem. The final infrastructure system is the internet. The internet operates...Enterprise Systems Analysis Technical Report SERC-2017-TR-106 April 30 2017 Principal Investigator: Dr. Michael Pennock, Stevens Institute...Date April 30, 2017 Copyright © 2017 Stevens Institute of Technology The Systems Engineering Research Center (SERC

  1. 基于DSP的直升机轴承振动信号检测系统设计%Helicopter Bearing Vibration Signal Detection System Based on DSP Processor

    Institute of Scientific and Technical Information of China (English)

    黄信杰; 俞子荣; 陈琼; 陈黎娟; 吴开志


    This paper mainly describes the design of a helicopter bearing vibration signal detection system based on TMS320F28335,and gives the realization principle,hardware structure and software design of the system.PCI bus communi-cation mode is adopted as the communication scheme of the system,and the parameters of the detection system can be easily realized by the upper computer software of the system.%主要叙述以TMS320F28335为核心的直升机轴承振动信号检测系统的设计,给出了系统的实现原理、硬件组成及相应的软件设计。采用PCI总线通信方式作为搭建系统的通信方案,利用该系统的上位机软件可方便地实现对检测系统的参数设置。该系统运用在直升机轴承故障诊断中,可以实时显示参数和图形化显示振动信号。

  2. Application of face-gear drives in helicopter transmissions (United States)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.


    The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

  3. Application of Face-Gear Drives in Helicopter Transmissions (United States)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.


    The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

  4. In-Flight Evaluation of Noise Levels and Assessment of Active Noise Reduction Systems in the Seahawk S-70B-2 Helicopter (United States)


    Library Qantas Airways Limited Civil Aviation Authority Gas & Fuel Corporation of Vic., Manager Scientific Services Ampol Petroleum (Vic) Pty Ltd...Aircraft 3 2.3 Recording and Measurement System 5 2.4 Analysis Equipment 5 2.5 Test Procedure 5 3. RESULTS 7 3.1 Ambient Noise Levels in the S-70B-2 7...using spectral analysis techniques to determine the acoustic characteristics of this noise, b) measuring at-ear SPLs under the ALPHA helmet and

  5. Feasibility study of a superconducting motor for electrical helicopter propulsion (United States)

    Simons, C. A. B. A. E.; Sanabria-Walter, C.; Polinder, H.


    During the past decades, superconducting electrical machines have become more suitable to replace conventional iron based designs, because of their lower weight and higher torque density. These properties make them good candidates for use in More Electric Aircraft (MEA). Especially helicopter propulsion systems could benefit from the increased performance. This paper describes the feasibility study of a superconducting motor to be used for helicopter propulsion as part of a More Electric Aircraft (MEA). For this, the armature, field windings and cryostat are designed, aiming at meeting the difficult specifications. Since superconductors have virtually no electrical resistance when cooled down below a certain critical temperature, they can be used to build high field and low weight coils for electrical machines. Especially the possibility to not use iron can make the superconducting motor lighter with a higher power density compared with conventional Permanent Magnet (PM) motors.

  6. Helicopter Icing Review. (United States)


    c CD 4- Z~L ~ ~L)~ u)z ~ ~ -4 z 4~ - -Ia. LnCD 9- CD C. Ln -i L.. L. c0 000 - -4 0000 0 0 o 00 CL -4- CD CDC CDUz 9- V) ) -cc C oL CD r 0LiDr- uDI system involved. o Icing conditions frequently occur in very moist air masses blowing inland from warmer seas, such as the Gulf of Mexico , the

  7. Computer Modelling of a Tank Battle with Helicopter Support

    Directory of Open Access Journals (Sweden)

    Chatter Singh


    Full Text Available The paper attempts to model a tank versus tank battle scenario in which the defender is provided an armed helicopter unit support, against surprise advance of the attacker towards an important place. The stochastic and dynamic nature of the battle system has been handled by means of Monte Carlo simulation. In that activities like move, search, fire, hit and kill are simulated and their effects generated in the model. The game has been repeated for parameters relating to (i fire power (ii mobility (iii intervisibility (iv blind shooting (v defender/attacker force ratio and (vi helicopter unit support with the defender. Then, average numerical effects in each case have been analysed.Although the results are based on tentative data, the. trend seems to suggest that a battalion of Centurion tanks or 2 coys with a helicopter unit support stand fairly good chance to defeat the attack by M-47/48 tanks equivalent to 4 coys. Neyertheless, the methodology provides an effective basis to systematically approach realistic situations and quantitatively assess weapon systems effectiveness under tactical alternatives and battle field environments.

  8. Random Vibration Analysis of an Integrated Airborne Aid Unit on Ambulance Helicopter%救护直升机机载急救单元随机振动分析

    Institute of Scientific and Technical Information of China (English)

    刘孝辉; 徐新喜; 白松; 谭树林; 杨猛


    为了解某救护直升机机载综合急救单元随机振动响应特性,针对载机平台振动特点,将载机宽带随机叠加正弦振动激励谱转换为ANSYS软件可用的纯随机振动谱,在ANSYS软件中建立了机载综合急救单元有限元模型,通过模态分析,获取了机载综合急救单元固有频率和振型。在此基础上施加转换后的载机振动谱并进行随机振动分析,得到了机载综合急救单元不同部位在激励频带范围内的动力响应及危险频率点,并对单元结构动强度进行了校核。仿真分析结果可为机载综合急救单元的抗减振设计提供参考依据。%To understand the random vibration reponse characteristics of the integrated airborne aid unit on ambulance helicopter, the finite element model of the unit was built by using ANSYS software. According to the vibration characteris-tics of the airborne platform of the ambulance helicopter, the randomly superimposed sinusoidal excitation spectrum of the airborne broadband was converted into a pure random vibration spectrum useable directly for ANSYS. The natural frequen-cies and modals of the unit were obtained by modal analysis. On this basis, the converted vibration spectrum was exerted so that the dynamic response and the critical frequencies in different positions of the integrated airborne aid unit were derived by the random vibration analysis. Meanwhile, the dynamic strength of the unit structure was checked up. The result of the analysis has provided a reference for anti-vibration design of the integrated airborne aid unit.

  9. Multidisciplinary System Reliability Analysis (United States)

    Mahadevan, Sankaran; Han, Song; Chamis, Christos C. (Technical Monitor)


    The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code, developed under the leadership of NASA Glenn Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multidisciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

  10. Combat Rescue Helicopter (CRH) (United States)


    capable of main base and austere location operations for worldwide PR missions. CRH system activities may be required during any phase of a service/joint...between planned Sikorsky labor and utilization of design center offload personnel. In some cases, less design hours were required. The unfavorable net...0.0 Labor Rate 0.0 Energy Rate 0.0 Technical Input 0.0 Other 0.0 Total Changes 0.0 Current Estimate 24529.5 CRH December 2015 SAR March 17, 2016 15

  11. The Vibration Impact Determination of the Helicopter Structural Components

    Directory of Open Access Journals (Sweden)

    Khaksar Zeinab


    Full Text Available This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

  12. Helicopter Electro-Optical System Display Requirements. 1. The Effects of CRT Display Size, System Gamma Function, and Terrain Type on Pilots’ Required Display Luminance (United States)


    field, a silicon-intensified TV camera (SIT) (GBC model NVC 100) was used here. Panel C shows a side view of the participant’s work station, which is...GBC model NVC 10U) that had a SIT camera tube to provide the video output. The probe (see Figure 4), with its symmetrical optical system and

  13. Selected Problems Of Transmission Wear Of The Mi-24 Helicopter

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej


    Full Text Available The hypothesis of mutual, destructive impact of the worn upper bearing of the WR-24 transmission on the Mi-24 helicopter's gearbox was stated. The Mi-24 is the only helicopter operated in Poland, in which the gearbox is mounted outside the main transmission – in the centre of the transmission shaft, between the main gearbox and the tail rotor. Damage to the gears in the gearbox of power generators is equivalent to termination of the tail rotor's drive. Such a termination immediately causes rotation of the body in the direction opposite to the direction of rotation of the main rotor. It is associated with the loss of lift and steering. It may lead to a disaster. Such an incident occurred in January 2011 in Afghanistan – both authors participated in its investigation. The authors, taking into account very good, almost legendary combat properties of the Mi-24, and their research of the specifics of wear and tear of the transmission elements, they think that, first, funds for development and implementation of the drive unit monitoring system should be made available specially for this helicopter. For this purpose, the authors propose to use the FAM-C method. It is characterised with significant ergonomics. Thank to this, multiple kinematic pairs can be observed simultaneously, and, therefore, the relationships between them as well.

  14. Advanced Scout Helicopter (ASH) Fly-by-Wire Flight Control System Preliminary Design. Volume 1. System Design and Analysis (United States)


    LI N N N ~L N N N N N ji J N t 0 0 - I - Li ACL Li LA. - LaN S z = N N N NIll * 0 0 0 0 0 0N 0 N N N LI LI LI LI - - N - ~Li, LAJO LaO LAO LaO LaON...type to permit back driving of motor sections that are shut down. A dual low-friction screw jack o1tall be used for the output. A brake with coils

  15. 直升机地面联合试验振动监测系统的开发及应用%Development and Application of Vibration Monitor System of Helicopter Ground Integrated Test

    Institute of Scientific and Technical Information of China (English)

    白莉; 龙贵华; 金坤健; 秦强; 马峰涛; 颜思淼; 刘昕


    According to the vibration monitor request of Helicopter Ground Unite Test, we develop a vibration monitor system based on PXIe test bus instru-ments, DAQ software “Explab”, UDP and LabVIEW vir-tual instruments. Here we describe the design, develop and accomplishment of the system, and prove its feasibility and validity by formal and informal tests.%针对直升机地面联合试验的振动监测需求,开发了一种基于PXIe测试总线设备、Explab数采软件、UDP网络传输模式和 LabVIEW虚拟仪器的振动监测系统。本文描述了直升机地面联合试验振动监测系统的设计、开发和实现,并通过前期调试和正式试验验证了系统的可行性和有效性。

  16. 基于DSP的微型直升机主动旋翼控制系统硬件设计%Hardware Design of Mini-helicopter Rotor Active Control System Based on DSP

    Institute of Scientific and Technical Information of China (English)

    刘宏; 罗华; 杨淑凤


    针对共轴双桨直升机主动旋翼控制的工作原理及其硬件设计方案进行了介绍.该系统主要由三轴加速度计ADXL345和三轴陀螺L3G4200D及TMS320F28335 DSP组成捷联惯导系统.并在捷联惯导姿态控制中增加了旋翼受力反馈环路,提高了惯导对外界扰动的响应速度.通过实验验证,该系统对于提高悬停稳定性和高度控制响应速度具有较好的效果.%The sculls coaxial helicopter active control of the working principle and hardware design solutions were introduced.The system consists of three-axis accelerometer ADXL345 three-axis gyro and L3G4200D and TMS320F28335 DSP components.And attitude control in strap down inertial navigation system(SINS) was added to rotor force feedback loop to improve the response to external disturbances.Experiments show that the system with good results to the hover stability and response speed of height control.

  17. Advanced airway management in an anaesthesiologist-staffed Helicopter Emergency Medical Service (HEMS): A retrospective analysis of 1047 out-of-hospital intubations. (United States)

    Piegeler, Tobias; Neth, Philippe; Schlaepfer, Martin; Sulser, Simon; Albrecht, Roland; Seifert, Burkhardt; Spahn, Donat R; Ruetzler, Kurt


    Airway management in the out-of-hospital emergency setting is challenging. Failed and even prolonged airway management is associated with serious clinical consequences, such as desaturation, bradycardia, airway injuries, or aspiration. The overall success rate of tracheal intubation ranges between 77% and 99%, depending on the level of experience of the provider. Therefore, advanced airway management should only be performed by highly-skilled and experienced providers. 9765 patients were treated in the out-of-hospital emergency setting by the anaesthesiologist-staffed Helicopter Emergency Medical Services (HEMS) between 2002 and 2014. Patients successfully intubated upon the first attempt were compared to patients who required more than one intubation attempts regarding several potential confounding factors such as age, gender, on-going CPR, NACA Score, initial GCS, prior administration of anaesthetic drugs, neuromuscular blocking agents, and vasopressors. 1573 out of 9765 patients (16.1%) required advanced airway management. 459 patients had already been intubated upon arrival of the HEMS, whereas 1114 patients (11.4%) underwent advanced airway management by the HEMS physician. 67 patients had to be excluded. Data for the remaining 1047 patients (790 males and 257 females) were analyzed further. Primary use of an alternative airway device was reported in 59 patients (5.6%), whereas 988 patients (94.4%) underwent laryngoscopy-guided tracheal intubation. 952 patients (96.4%) could be intubated upon the first attempt and overall intubation success was 99.5% (983 out of 988). Our study demonstrates that HEMS physicians performed airway management frequently and that both the first attempt as well as the overall success rate of tracheal intubation was high. Together with the fact that all failed and difficult intubations were successfully recognized and handled and that no surgical airway had to be established, the current study once more underlines the importance of


    Directory of Open Access Journals (Sweden)

    Valentin BUTOESCU


    Full Text Available A vortex model of a helicopter rotor is presented. Each blade of the rotor has three degrees of freedom: flapping, lagging and feathering. The motions after each degree of freedom are also known for all blades. The blade is modelled as a thin vortex surface. The wakes are free fluid surfaces. A system of five equations are obtained: the first one is the integral equation of the lifting surface (rotor, the next three describe the wakes motion, and the last one relates the vortex strength on the wakes and the variation of vorticity on the rotor. A numerical solution of this system is presented. To avoid the singularities that can occur due to the complexity of vortex system, a desingularized model of the vortex core was adopted. A Mathcad worksheet containing the method has been written.The original contribution of the work. The calculation method of the motion of the wakes free vortex system, the development of the vortex cores in time and a new method to approximate the aerodynamic influence of remoted wake regions.

  19. Design and Testing of Flight Control Laws on the RASCAL Research Helicopter (United States)

    Frost, Chad R.; Hindson, William S.; Moralez. Ernesto, III; Tucker, George E.; Dryfoos, James B.


    Two unique sets of flight control laws were designed, tested and flown on the Army/NASA Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) JUH-60A Black Hawk helicopter. The first set of control laws used a simple rate feedback scheme, intended to facilitate the first flight and subsequent flight qualification of the RASCAL research flight control system. The second set of control laws comprised a more sophisticated model-following architecture. Both sets of flight control laws were developed and tested extensively using desktop-to-flight modeling, analysis, and simulation tools. Flight test data matched the model predicted responses well, providing both evidence and confidence that future flight control development for RASCAL will be efficient and accurate.

  20. Heavy Lift Helicopter - Cargo Handling ATC Program. Volume I. Detail Design Structural and Weights Analysis, and Static and Dynamic Load Analysis (United States)


    Component (ATC) Program was to minimize technical, cost, and schedule risks associated with the future HLH system RDTE and produccion programs. This...Provisions are included on the actuator for manual operation by depressing and rotating a squared shaft at the upper end of the drum. Electrical limit...opened by ground personnel using the manual knob only. The above design is developed on the basis of capability of releasing the complete pendant from the

  1. Fuzzy Control of Yaw and Roll Angles of a Simulated Helicopter Model Includes Articulated Manipulators

    Directory of Open Access Journals (Sweden)

    Hossein Sadegh Lafmejani


    Full Text Available Fuzzy logic controller (FLC is a heuristic method by If-Then Rules which resembles human intelligence and it is a good method for designing Non-linear control systems. In this paper, an arbitrary helicopter model includes articulated manipulators has been simulated with Matlab SimMechanics toolbox. Due to the difficulties of modeling this complex system, a fuzzy controller with simple fuzzy rules has been designed for its yaw and roll angles in order to stabilize the helicopter while it is in the presence of disturbances or its manipulators are moving for a task. Results reveal that a simple FLC can appropriately control this system.

  2. Harmonic analysis and optimized vibration sensor locations of the helicopter intermediate gearbox%直升机中减速器谐响应分析与传感器优化布局

    Institute of Scientific and Technical Information of China (English)

    苏勋文; 王少萍; 朱冬梅; 石健


    研究了多自由度的振动数学模型.通过系统的故障频率来确定振动传感器的安装位置,提出了一种基于故障频率敏感的振动传感器优化布局方法,建立了直升机中减速器机匣有限元模型.利用谐响应分析方法,对中减速器机匣施加一故障激励信号.研究表明:机匣的不同位置对激励信号响应的振动幅值明显不同,齿轮故障时往往在啮合频率及其倍频处形成以转频为间隔的边频带,对该边频响应振幅最大的位置就是振动传感器安装的最佳位置,并提出了振动传感器优化布局函数.此方法同样适用于直升机传动系统其它部件的振动传感器位置选择,也适用于其它旋转机械的振动监测.%Multi-freedom vibration model location, in which the amplitude was sensitive has been studied. A methodology of optimized vibration sensor to fault frequency, was presented. First, a finite element model of the helicopter intermediate gearbox was constructed, then a signal stimulus was forced to the gearbox of the model by the method of harmonic analysis. The study shows that different locations have clear different amplitudes according to the signal stimulus. So the location, where the amplitude was the largest, should be the best sensor location and a function of optimized sensor locations was presented. This optimized sensor location methodology is also applicable to other parts of the helicopter transmission and other rotating mechanics.

  3. Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm (United States)

    Zhang, Diantang; Chen, Li; Sun, Ying; Zhang, Yifan; Qian, Kun


    A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process.

  4. Identification, control and visually-guided behavior for a model helicopter (United States)

    Saripalli, Srikanth

    Research on unmanned aerial vehicles is motivated by applications where human intervention is impossible, risky or expensive e.g. hazardous material recovery, traffic monitoring, disaster relief support, military operations etc. Due to its vertical take-off, landing and hover capabilities, a helicopter is an attractive platform for such applications. There are significant challenges to building an autonomous robotic helicopter - these span the areas of system identification, low-level control, state estimation, and planning. Towards the goal of fully-autonomous helicopters this thesis makes the following contributions. A continuous-discrete extended Kalman filter has been developed that combines inertial data with GPS and compass data to provide estimates of the 6DOF state of the helicopter. Using this filter a model for the helicopter has been identified based on frequency response techniques. The model has been validated in flight tests on a small helicopter testbed (1.6 m rotor diameter) at speeds upto 5 m/s. Based on evidence from this model a decoupled low-level controller has been developed which is embedded in a control architecture suitable for visually-guided navigation. As a novel application, we show how such a controller can be used to perform trajectory following on the helicopter where the desired trajectories are typical spacecraft landing trajectories, and the only controls available are thrusters. This in effect, produces a low-cost testbed for testing spacecraft landing and hazard avoidance on a planetary surface. Finally, we develop and extensively experimentally characterize algorithms for vision-based autonomous landing, object tracking, and sensor deployment.

  5. 带有差分GPS的多传感器无人直升机航测遥感系统%An unmanned helicopter based mapping system with differential GPS and multi-Sensor

    Institute of Scientific and Technical Information of China (English)

    陈天恩; 长井正彦; 柴崎亮介


    Low-altitude UAV( Unmanned Aerial Vehicles) based mapping system is a new type of spatial information acquisition and processing equipment overall the world in recent years. It takes UAV equipped with camera systems, GPS receivers, IMU, laser scanners,automatic flight control systems and other equipments as a platform to obtain ground information in flexible,fast and efficient, precise and accurate, safe, reliable, low operating cost, wide application characteristics, and has been used in the digital city rapid updates , the new rural surveying and mapping support services, emergency disaster relief, etc. It could be taken as an important supplementary means of satellite remote sensing and traditional aerial photography methods. This paper described an unmanned helicopter based mapping system developed by the authors in Japan. The system is equipped with differential GPS and IMU for direct geographic location and orientation with fewer or without ground control points. The onboard laser scanner could be used to collect ground surface model directly georeferenced through the post processed GPS/IMU data and triangulation with the images captured with onboard cameras. The geometric accuracy of the system was verified with actual flight data, and the results showed that the system could be used to map large-scale topographic maps and other areas of application.%本文主要介绍作者在日本研制的一种基于无人直升机平台的多种传感器航测遥感系统,它直接采用GPS和IMU数据进行地理定位定向而不需要地面控制点.通过实飞数据对系统达到的几何精度进行了验证,结果表明该系统可用来测绘大比例尺地形图以及应用于其他相关领域.

  6. Static strain and vibration characteristics of a metal semimonocoque helicopter tail cone of moderate size (United States)

    Bielawa, Richard L.; Hefner, Rachel E.; Castagna, Andre


    The results are presented of an analytic and experimental research program involving a Sikorsky S-55 helicopter tail cone directed ultimately to the improved structural analysis of airframe substructures typical of moderate sized helicopters of metal semimonocoque construction. Experimental static strain and dynamic shake-testing measurements are presented. Correlation studies of each of these tests with a PC-based finite element analysis (COSMOS/M) are described. The tests included static loadings at the end of the tail cone supported in the cantilever configuration as well as vibrational shake-testing in both the cantilever and free-free configurations.

  7. 某直升机机载设备印制板振动试验失效分析%PCB Vibration Test Failure Analysis for Helicopter-borne Equipment

    Institute of Scientific and Technical Information of China (English)



    文中以某机载电子设备振动试验中印制板(PCB)故障现象为研究对象,通过理论分析和ANSYS动力学计算的方法对PCB板产生故障的机理进行了分析和计算。计算结果与试验现象相符,认为谐振和PCB板设计问题是导致该试验故障的原因,并在结构接口方面对引起谐振的情况进行了分析,阐述了结构和电讯方面相应的改进措施。%The mechanism which results in the PCB failure in a vibration test for the helicopter-borne electronic equipment is described in this paper by theoretical analysis and ANSYS dynamic calculation.The calculation results agree with the test phenomenon.Resonance and defects in PCB design are determined as the reasons of the PCB failure.The structural interface problem which results in the resonance is analyzed.And the structural and electronic improvement measures are introduced,too.

  8. Experimental Validation of a Compound Control Scheme for a Two-Axis Inertially Stabilized Platform with Multi-Sensors in an Unmanned Helicopter-Based Airborne Power Line Inspection System

    Directory of Open Access Journals (Sweden)

    Xiangyang Zhou


    Full Text Available A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP with multi-sensors applied to an unmanned helicopter (UH-based airborne power line inspection (APLI system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from power supply and motor back electromotive force (BEMF on control precision. In this way, the stabilization accuracy of the ISP is greatly improved. The rate loop, which is the middle one, is used to improve sensor’s stability precision through compensating for various disturbances. To ensure the pointing accuracy of the line of sight (LOS of multi-sensors, the position loop is designed to be the outer one and acts as the main feedback path, by which the accurate pointing angular position is achieved. To validate the scheme, a series of experiments were carried out. The results show that the proposed compound control scheme can achieve reliable control precision and satisfy the requirements of real APLI tasks.


    Institute of Scientific and Technical Information of China (English)

    黄晓东; 王卫卫; 蒋玮光


    直升机旋翼系统是直升机的核心部件,弹性轴承将桨叶与桨毂相连,提供桨叶的挥舞、摆振和变距自由度,刚度特性是其主要的力学性能.通过采用松紧螺套驱动半圆形夹具转动来测试弹性轴承压缩、扭转和弯曲刚度特性,结果表明该试验方法新颖独特,具有一定的通用性,能准确判定弹性轴承是否合格,可为不同机型的弹性轴承提供装机前试验的方法.%Rotor system is the core component of the helicopter, flexible blade with the spherical thrust bearing connected to provide the wielding, shimmy and pitch degrees of freedom, the stiffness characteristics is one of the main mechanical properties. Test the spherical thrust bearing compression, torsion and bending stiffness characteristics by twisting the screw to drive the semicircular fixture. These results indicated that the test method is distinctive and general. It can accurately determine whether the spherical thrust bearing is qualified and provide a test before installing for different type of spherical thrust bearings.


    Energy Technology Data Exchange (ETDEWEB)

    M. Salem


    The purpose and objective of this analysis is to systematically identify and evaluate hazards related to the Yucca Mountain Project Exploratory Studies Facility (ESF) surface and subsurface conveyor system (for a list of conveyor subsystems see section 3). This process is an integral part of the systems engineering process; whereby safety is considered during planning, design, testing, and construction. A largely qualitative approach was used since a radiological System Safety Analysis is not required. The risk assessment in this analysis characterizes the accident scenarios associated with the conveyor structures/systems/components in terms of relative risk and includes recommendations for mitigating all identified risks. The priority for recommending and implementing mitigation control features is: (1) Incorporate measures to reduce risks and hazards into the structure/system/component (S/S/C) design, (2) add safety devices and capabilities to the designs that reduce risk, (3) provide devices that detect and warn personnel of hazardous conditions, and (4) develop procedures and conduct training to increase worker awareness of potential hazards, on methods to reduce exposure to hazards, and on the actions required to avoid accidents or correct hazardous conditions. The scope of this analysis is limited to the hazards related to the design of conveyor structures/systems/components (S/S/Cs) that occur during normal operation. Hazards occurring during assembly, test and maintenance or ''off normal'' operations have not been included in this analysis. Construction related work activities are specifically excluded per DOE Order 5481.1B section 4. c.

  11. Digital Systems Analysis (United States)

    Martin, Vance S.


    There have been many attempts to understand how the Internet affects our modern world. There have also been numerous attempts to understand specific areas of the Internet. This article applies Immanuel Wallerstein's World Systems Analysis to our informationalist society. Understanding this world as divided among individual core, semi-periphery,…




  13. Digital Systems Analysis (United States)

    Martin, Vance S.


    There have been many attempts to understand how the Internet affects our modern world. There have also been numerous attempts to understand specific areas of the Internet. This article applies Immanuel Wallerstein's World Systems Analysis to our informationalist society. Understanding this world as divided among individual core, semi-periphery,…

  14. A helicopter emergency medical service may allow faster access to highly specialised care

    DEFF Research Database (Denmark)

    Afzali, Monika; Hesselfeldt, Rasmus; Steinmetz, Jacob


    Centralization of the hospital system entails longer transport for some patients. A physician-staffed helicopter may provide effective triage, advanced management and fast transport to highly specialized treatment for time-critical patients. The aim of this study was to describe activity and poss......Centralization of the hospital system entails longer transport for some patients. A physician-staffed helicopter may provide effective triage, advanced management and fast transport to highly specialized treatment for time-critical patients. The aim of this study was to describe activity...

  15. US Helicopter Expands Service to Newark Liberty International Airport

    Institute of Scientific and Technical Information of China (English)


    @@ US Helicopter Corporation ("US Helicopter") (OTC Bulletin Board: USHP) and Continental Airlines (NYSE: CAL)announced a partnership to provide eight-minute shuttle service between Manhattan and Newark Liberty International Airport beginning Dec.18, 2006.

  16. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.


    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for

  17. Integrated locating of helicopter stations and helipads for wounded transfer under demand location uncertainty. (United States)

    Bozorgi-Amiri, Ali; Tavakoli, Shayan; Mirzaeipour, Hossein; Rabbani, Masoud


    Health emergency medical service (HEMS) plays an important role in reducing injuries by providing advanced medical care in the shortest time and reducing the transfer time to advanced treatment centers. In the regions without ground relief coverage, it would be faster to transfer emergency patients to the hospital by a helicopter. In this paper, an integer nonlinear programming model is presented for the integrated locating of helicopter stations and helipads by considering uncertainty in demand points. We assume three transfer modes: (1) direct transfer by an ambulance, (2) transfer by an ambulance to a helicopter station and then to the hospital by a helicopter, (3) transfer by an ambulance to a predetermined point and then to the hospital by a helicopter. We also assume that demands occur in a square-shaped area, in which each side follows a uniform distribution. It is also assumed that demands in an area decrease errors in the distances between each two cities. The purpose of this model is to minimize the transfer time from demand points to the hospital by considering different modes. The proposed model is examined in terms of validity and applicability in Lorestan Province and a sensitivity analysis is also conducted on the total allocated budget. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Dynamics of a split torque helicopter transmission (United States)

    Rashidi, Majid; Krantz, Timothy

    A high reduction ratio split torque gear train has been proposed as an alternative to a planetary configuration for the final stage of a helicopter transmission. A split torque design allows a high ratio of power-to-weight for the transmission. The design studied in this work includes a pivoting beam that acts to balance thrust loads produced by the helical gear meshes in each of two parallel power paths. When the thrust loads are balanced, the torque is split evenly. A mathematical model was developed to study the dynamics of the system. The effects of time varying gear mesh stiffness, static transmission errors, and flexible bearing supports are included in the model. The model was demonstrated with a test case. Results show that although the gearbox has a symmetric configuration, the simulated dynamic behavior of the first and second compound gears are not the same. Also, results show that shaft location and mesh stiffness tuning are significant design parameters that influence the motions of the system.

  19. Dynamic surface measurements on a model helicopter rotor during blade slap at high angles of attack (United States)

    Hubbard, J. E., Jr.; Harris, W. L.


    The modern helicopter offers a unique operational capability to both the public and private sectors. However, the use of the helicopter may become severely limited due to the radiated noise generated by the rotor system. A description is presented of some of the experimental results obtained with a model helicopter rotor in an anechoic wind tunnel with regard to blade stall as a source mechanism of blade slap. Attention is given to dynamic rotor blade surface phenomena and the resulting far field impulsive noise from the model helicopter rotor at high angles of attack and low tip speed. The results of the investigation strongly implicates the boundary layer as playing an important role in blade slap due to blade/vortex interaction (BVI) in a highly loaded rotor. Intermittent stall cannot be ruled out as a possible source mechanism for blade slap. This implies that blade surface characteristics, airfoil shape and local Reynolds number may now be used as tools to reduce the resultant far-field sound pressure levels in helicopters.

  20. New capabilities and recent research programs of the NASA/Army CH-47B variable-stability helicopter (United States)

    Hindson, W. S.; Hilbert, K. B.; Tucker, G. E.; Chen, R. T. N.; Fry, E. B.


    The CH-47B is the third in a series of variable-stability helicopters developed and operated by NASA since 1952 to investigate helicopter and VTOL handling qualities. Recently, several new capabilities were added to this helicopter to enable it to better support new and evolving research requirements. The installation of a programmable force-feel system for the evaluation pilot's conventional cyclic stick, and a four-axis side-stick controller permit a range of in-flight investigations concerning manipulator characteristics and augmentation system features that had not been possible with earlier NASA research helicopters. A recently installed color electronic display system with a programmable symbol generator will permit the investigation of display formats for a variety of VTOL and helicopter missions. Finally, a powerful new general-purpose flight computer is now in operation. It is programmable in high-level languages and will provide more efficient support of research programs. In addition to these new hardware capabilities, flight-control software has been developed to improve the in-flight simulation capability of the aircraft. A brief description of the CH-47B's variable-stability research equipment is provided, recent research programs are summarized, and some remarks concerning the potential of the helicopter are presented.

  1. 78 FR 54380 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ..., AS355F1, and AS355F2 helicopters with an autopilot installed; Model AS350B3 helicopters with an autopilot or modification 073252 installed; and Model AS355N and AS355NP helicopters with an autopilot or..., AS350D, AS355E, AS355F, AS355F1, AS355F2, AS355N, and AS355NP helicopters with either an autopilot...

  2. A comparison of the association of helicopter and ground ambulance transport with the outcome of injury in trauma patients transported from the scene. (United States)

    Cunningham, P; Rutledge, R; Baker, C C; Clancy, T V


    Comprehensive emergency medical services and helicopter aeromedical transport systems have been developed based on the principle that early definitive care improves outcome. The purpose of this study was to compare outcomes between patients transported by helicopter and those transported by ground. Data were obtained from the North Carolina Trauma Registry for the period between 1987 and 1993 on all patients transported by helicopter and ground admitted to one of the eight state designated trauma centers. Study patients included only those who were transported directly from the scene of injury to the trauma center (interhospital transfers were excluded). Mortality (outcome) was compared after patient stratification by injury severity and transport time, using Cochran-Mantel-Haenszel statistics and logistic regression-derived probabilities of survival. One thousand three hundred forty-six patients (7.3% of the total) were transported from scene to trauma center by helicopter and 17,144 were transported by ground. In patients transported by helicopter, the mean Trauma Score was lower (12 +/- 3.6) versus 14.3 +/- 3.6 (p ground ambulance have low injury severity measures. Outcomes were not uniformly better among patients transported by helicopter. Only a very small subset of patients transported by helicopter appear to have any chance of improved survival based on their helicopter transport. This study suggests that further effort should be expended to try to better identify patients who may benefit from this expensive and risky mode of transport.

  3. Condition Monitoring of Helicopter Gearboxes by Embedded Sensing (United States)

    Suryavanashi, Abhijit; Wang, Shengda; Gao, Robert; Danai, Kourosh; Lewicki, David G.


    Health of helicopter gearboxes is commonly assessed by monitoring the housing vibration, thus it is challenged by poor signal-to-noise ratio of the signal measured away from the source. It is hypothesized that vibration measurements from sensors placed inside the gearbox will be much clearer indicators of faults and will eliminate many of the difficulties faced by present condition monitoring systems. This paper outlines our approach to devising such a monitoring system. Several tasks have been outlined toward this objective and the strategy to address each has been described. Among the tasks are wireless sensor design, antenna design, and selection of sensor locations.

  4. Dynamics Control Approaches to Improve Vibratory Environment of the Helicopter Aircrew (United States)

    Wickramasinghe, Viresh Kanchana

    Although helicopter has become a versatile mode of aerial transportation, high vibration levels leads to poor ride quality for its passengers and aircrew. Undesired vibration transmitted through the helicopter seats have been known to cause fatigue and discomfort to the aircrew in the short-term as well as neck strain and back pain injuries due to long-term exposure. This research study investigated the use of novel active as well as passive methodologies integrated in helicopter seats to mitigate the aircrew exposure to high vibration levels. Due to significantly less certification effort required to modify the helicopter seat structure, application of novel technologies to the seat is more practical compared to flight critical components such as the main rotor to reduce aircrew vibration. In particular, this research effort developed a novel adaptive seat mount approach based on active vibration control technology. This novel design that incorporated two stacked piezoelectric actuators as active struts increases the bending stiffness to avoid the low frequency resonance while generating forces to counteract higher harmonic vibration peaks. A real-time controller implemented using a feed-forward algorithm based on adaptive notches counteracted the forced vibration peaks while a robust feedback control algorithm suppressed the resonance modes. The effectiveness of the adaptive seat mount system was demonstrated through extensive closed-loop control tests on a full-scale helicopter seat using representative helicopter floor vibration profiles. Test results concluded that the proposed adaptive seat mount approach based on active control technology is a viable solution for the helicopter seat vibration control application. In addition, a unique flight test using a Bell-412 helicopter demonstrated that the aircrew is exposed to high levels of vibration during flight and that the whole body vibration spectrum varied substantially depending on operating conditions as

  5. Automated document analysis system (United States)

    Black, Jeffrey D.; Dietzel, Robert; Hartnett, David


    A software application has been developed to aid law enforcement and government intelligence gathering organizations in the translation and analysis of foreign language documents with potential intelligence content. The Automated Document Analysis System (ADAS) provides the capability to search (data or text mine) documents in English and the most commonly encountered foreign languages, including Arabic. Hardcopy documents are scanned by a high-speed scanner and are optical character recognized (OCR). Documents obtained in an electronic format bypass the OCR and are copied directly to a working directory. For translation and analysis, the script and the language of the documents are first determined. If the document is not in English, the document is machine translated to English. The documents are searched for keywords and key features in either the native language or translated English. The user can quickly review the document to determine if it has any intelligence content and whether detailed, verbatim human translation is required. The documents and document content are cataloged for potential future analysis. The system allows non-linguists to evaluate foreign language documents and allows for the quick analysis of a large quantity of documents. All document processing can be performed manually or automatically on a single document or a batch of documents.

  6. Network systems security analysis (United States)

    Yilmaz, Ä.°smail


    Network Systems Security Analysis has utmost importance in today's world. Many companies, like banks which give priority to data management, test their own data security systems with "Penetration Tests" by time to time. In this context, companies must also test their own network/server systems and take precautions, as the data security draws attention. Based on this idea, the study cyber-attacks are researched throughoutly and Penetration Test technics are examined. With these information on, classification is made for the cyber-attacks and later network systems' security is tested systematically. After the testing period, all data is reported and filed for future reference. Consequently, it is found out that human beings are the weakest circle of the chain and simple mistakes may unintentionally cause huge problems. Thus, it is clear that some precautions must be taken to avoid such threats like updating the security software.

  7. 77 FR 44434 - Airworthiness Directives; Various Restricted Category Helicopters (United States)


    ... State University); Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); California... Services (previously Erickson Air-Crane Co.); California Department of Forestry; Garlick Helicopters, Inc... (previously Erickson Air-Crane Co.); California Department of Forestry; Garlick Helicopters, Inc.; Global...

  8. 78 FR 47531 - Airworthiness Directives; Various Restricted Category Helicopters (United States)


    ... Component Overhaul Schedule, Revision 11, dated April 30, 2010, of Bell Helicopter Textron, Inc. (BHTI), BHT... Schedule, Revision 11, dated April 30, 2010, of Bell Helicopter Textron, Inc., BHT-212- MM-1, Revision 13... Helicopter Textron, Inc., BHT-212-MM-1, Revision 13, dated September 16, 2010. (3) For BHTI service...

  9. 78 FR 18230 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... sides of the helicopter. This AD was prompted by a crack and failure of a cabin vibration damper blade... 2007-SW-053-AD. (a) Applicability This AD applies to Model EC130 B4 helicopters with a cabin vibration..., install a vibration damper casing assembly on both sides of the helicopter by following paragraphs...

  10. System Reliability Analysis: Foundations. (United States)


    performance formulas for systems subject to pre- ventive maintenance are given. V * ~, , 9 D -2 SYSTEM RELIABILITY ANALYSIS: FOUNDATIONS Richard E...reliability in this case is V P{s can communicate with the terminal t = h(p) Sp2(((((p p)p) p)p)gp) + p(l -p)(((pL p)p)(p 2 JLp)) + p(l -p)((p(p p...For undirected networks, the basic reference is A. Satyanarayana and Kevin Wood (1982). For directed networks, the basic reference is Avinash

  11. A General Simulink System of Feedforward Vibration Control and Its Application for Helicopter Vibration Control%通用的前馈振动控制Simulink仿真系统及其应用

    Institute of Scientific and Technical Information of China (English)

    鲁民月; 顾仲权


    The general simulation systems for feedforward vibration control based on adaptive filter technique are set up on the base of Simulink platform.According to these simulation systems the active control of structural responses for helicopter is simulated.In order to simulate the mechanical behaviors of the plant,a free-free beam model with servo-hydraulic inertial actuator is used,which is excited by dual-harmonic force.On this model some adaptive filters,such as FIR,SIIR,are independently used to identify and control the vibration system.Based on the simulation studies for different kinds of control modes and corresponding algorithms,the features,such as asymptotic of algorithm,the rate of convergence are discovered.Finally,some useful comments are given for further research.%利用Simulink平台,建立一个基于自适应滤波技术的前馈振动控制的通用仿真系统,并对直升机结构响应主动控制进行仿真研究。为了摸拟机体的力学特性以及旋翼对机体的激振作用,本文建立了一个带伺服液压惯性式作动器的自由一自由梁模型,并使之处于双频扰力作用下,对于该模型,采用了FIR,SIIR等滤波模型进行识别和控制。通过对不同控制模式和与之相适应的滤波算法的仿真研究,揭示其算法收敛性和收敛速度等特性。

  12. Design of a simple active controller to suppress helicopter air resonance (United States)

    Takahashi, M. D.; Friedmann, P. P.


    A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. Using this mathematical model, a nominal configuration is selected that experiences an air resonance instability throughout most of its flight envelope. A simple multivariable compensator using conventional swashplate inputs and a single body roll rate measurement is then designed. The controller design is based on a linear estimator in conjunction with optimal feedback gains, and the design is done in the frequency domain using the Loop Transfer Recovery method. The controller is shown to suppress the air resonance instability throughout wide range helicopter loading conditions and forward flight speeds.

  13. DART system analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Boggs, Paul T.; Althsuler, Alan (Exagrid Engineering); Larzelere, Alex R. (Exagrid Engineering); Walsh, Edward J.; Clay, Ruuobert L.; Hardwick, Michael F. (Sandia National Laboratories, Livermore, CA)


    The Design-through-Analysis Realization Team (DART) is chartered with reducing the time Sandia analysts require to complete the engineering analysis process. The DART system analysis team studied the engineering analysis processes employed by analysts in Centers 9100 and 8700 at Sandia to identify opportunities for reducing overall design-through-analysis process time. The team created and implemented a rigorous analysis methodology based on a generic process flow model parameterized by information obtained from analysts. They also collected data from analysis department managers to quantify the problem type and complexity distribution throughout Sandia's analyst community. They then used this information to develop a community model, which enables a simple characterization of processes that span the analyst community. The results indicate that equal opportunity for reducing analysis process time is available both by reducing the ''once-through'' time required to complete a process step and by reducing the probability of backward iteration. In addition, reducing the rework fraction (i.e., improving the engineering efficiency of subsequent iterations) offers approximately 40% to 80% of the benefit of reducing the ''once-through'' time or iteration probability, depending upon the process step being considered. Further, the results indicate that geometry manipulation and meshing is the largest portion of an analyst's effort, especially for structural problems, and offers significant opportunity for overall time reduction. Iteration loops initiated late in the process are more costly than others because they increase ''inner loop'' iterations. Identifying and correcting problems as early as possible in the process offers significant opportunity for time savings.

  14. Helicopter industry - early beginnings to now; an outlook on the helicopter market and its major players in the rotorcraft industry

    NARCIS (Netherlands)

    Spranger, L.


    The helicopter is probably the most flexible aircraft that we know today. Although its history dates back to around 1500, the first practical helicopter wasn’t manufactured until the 1940s, roughly three decades after the Wright brothers’ first powered human flight. Today, helicopters fulfil a wide

  15. Aeroelastic analysis for helicopter rotor blades with time-variable, non-linear structural twist and multiple structural redundancy: Mathematical derivation and program user's manual (United States)

    Bielawa, R. L.


    The differential equations of motion for the lateral and torsional deformations of a nonlinearly twisted rotor blade in steady flight conditions together with those additional aeroelastic features germane to composite bearingless rotors are derived. The differential equations are formulated in terms of uncoupled (zero pitch and twist) vibratory modes with exact coupling effects due to finite, time variable blade pitch and, to second order, twist. Also presented are derivations of the fully coupled inertia and aerodynamic load distributions, automatic pitch change coupling effects, structural redundancy characteristics of the composite bearingless rotor flexbeam - torque tube system in bending and torsion, and a description of the linearized equations appropriate for eigensolution analyses. Three appendixes are included presenting material appropriate to the digital computer program implementation of the analysis, program G400.

  16. Reporting Helicopter Emergency Medical Services in Major Incidents

    DEFF Research Database (Denmark)

    Fattah, Sabina; Johnsen, Anne Siri; Sollid, Stephen J M


    OBJECTIVE: Research on helicopter emergency medical services (HEMS) in major incidents is predominately based on case descriptions reported in a heterogeneous fashion. Uniform data reported with a consensus-based template could facilitate the collection, analysis, and exchange of experiences...... interacted through e-mail. We asked these experts to define data variables and rank which were most important to report during an immediate prehospital medical response to a major incident. Five rounds were conducted. RESULTS: In the first round, the experts suggested 98 variables. After 5 rounds, 21...

  17. Patient and trauma center characteristics associated with helicopter emergency medical services transport for patients with minor injuries in the United States. (United States)

    Cheung, Brian H; Delgado, M Kit; Staudenmayer, Kristan L


    Helicopter emergency medical services (EMS) transport is expensive, and previous work has shown that cost-effective use of this resource is dependent on the proportion of minor injuries flown. To understand how overtriage to helicopter EMS versus ground EMS can be reduced, it is important to understand factors associated with helicopter transport of patients with minor injuries. The aim was to characterize patient and hospital characteristics associated with helicopter transport of patients with minor injuries. This was a retrospective analysis of adults ≥18 years who were transported by helicopter to Level I/II trauma centers from 2009 through 2010 as identified in the National Trauma Data Bank. Minor injuries were defined as all injuries scored at an Abbreviated Injury Scale (AIS) score of trauma (OR = 2.52, 95% CI = 2.12 to 3.00). Being flown with minor injuries was more likely if the patient was transported to a trauma center that also received a high proportion of patients with minor injuries by ground EMS (OR = 1.89, 95% CI = 1.58 to 2.26) or a high proportion of EMS traffic by helicopter (OR = 1.35, 95% CI = 1.02 to 1.78). No significant association with urban-rural scene location or EMS transport time was found. Better recognizing which patients with falls and penetrating trauma have serious injuries that could benefit from being flown may lead to the more cost-effective use of helicopter EMS. More research is needed to determine why patients without insurance, who are most at risk for high out-of-pocket expenses from helicopter EMS, are at higher risk for being flown when only having minor injuries. This suggests that interventions to optimize cost-effectiveness of helicopter transport will likely require an evaluation of helicopter triage guidelines in the context of regional and patient needs. © 2014 by the Society for Academic Emergency Medicine.

  18. Workload and operational fatigue in helicopter pilots. (United States)

    Rotondo, G


    In light of the modern aetiopathogenic views, a brief review was made concerning possible causes of operational fatigue to which flying personnel in general are exposed in the exercise of flying activity. The author then describes and analyzes the meaning and importance of the various stressing factors that constitute the physical and psychic workload to which the helicopter pilot is subjected in performing his professional activities. Also analyzed are the influences exercised, both separately and jointly, on the genesis of flight fatigue in helicopter pilots by stressing and fatiguing effects of vibrations, noise, and psycho-emotional and psycho-sensorial factors related to the variety and danger of utilization of this modern aircraft. Such an analytical investigation enables the author to conclude that one must admit that helicopter piloting involves a psycho-physical workload certainly no less than that required by more powerful and faster aircraft.

  19. Analysis of bilinear stochastic systems (United States)

    Willsky, A. S.; Martin, D. N.; Marcus, S. I.


    Analysis of stochastic dynamical systems that involve multiplicative (bilinear) noise processes. After defining the systems of interest, consideration is given to the evolution of the moments of such systems, the question of stochastic stability, and estimation for bilinear stochastic systems. Both exact and approximate methods of analysis are introduced, and, in particular, the uses of Lie-theoretic concepts and harmonic analysis are discussed.

  20. Helicopter trajectory planning using optimal control theory (United States)

    Menon, P. K. A.; Cheng, V. H. L.; Kim, E.


    A methodology for optimal trajectory planning, useful in the nap-of-the-earth guidance of helicopters, is presented. This approach uses an adjoint-control transformation along with a one-dimensional search scheme for generating the optimal trajectories. In addition to being useful for helicopter nap-of-the-earth guidance, the trajectory planning solution is of interest in several other contexts, such as robotic vehicle guidance and terrain-following guidance for cruise missiles and aircraft. A distinguishing feature of the present research is that the terrain constraint and the threat envelopes are incorporated in the equations of motion. Second-order necessary conditions are examined.

  1. CMU's autonomous helicopter explores new territory. (United States)

    Charles, J.


    In the summer of 1998, several members of Carnegie Mellon University's (CMUs) Autonomous Helicopter Project team joined NASA on a multidisciplinary expedition to the Canadian Arctic's Haughton Crater. NASA was willing to travel to such a remote corner of the globe because of its similarity to an even more remote locale - Mars. Researchers are studying the 23-million-year-old meteorite impact crater in the hope of learning more about Mars's environment. While there, they also tested a number of technologies that will enable future exploration of Mars, including CMU's autonomous helicopter.

  2. Prehospital airway management on rescue helicopters in the United Kingdom. (United States)

    Schmid, M; Mang, H; Ey, K; Schüttler, J


    Adequate equipment is one prerequisite for advanced, out of hospital, airway management. There are no data on current availability of airway equipment on UK rescue helicopters. An internet search revealed all UK rescue helicopters, and a questionnaire was sent to the bases asking for available airway management items. We identified 27 helicopter bases and 26 (96%) sent the questionnaire back. Twenty-four bases (92%) had at least one supraglottic airway device; 16 (62%) helicopters had material for establishing a surgical airway (e.g. a cricothyroidotomy set); 88% of the helicopters had CO(2) detection; 25 (96%) helicopters carried automatic ventilators; among these, four (15%) had sophisticated ventilators and seven (27%) helicopters carried special face masks suitable for non-invasive ventilation. We found a wide variation in the advanced airway management equipment that was carried routinely on air ambulances. Current guidelines for airway management are not met by all UK air ambulances.

  3. SCATHA-Analysis System (United States)


    experiment, tape number, or day. 7 Sk* A1 .A Data Analysis System Functional Flow SAK SCF Agency Agency TapesAec Aec I-, TaFgur 1ap 8C C The digital data then...Mainframe 13 MF word 41 (Subcom) Containing Subcom 14 NIF word 53 (D4002) Level 0 15 MF word 85 (D4001) 16 MF word 102 (Subcom) 17 MF word 103 (Subcom...16 MF word 105 17 NIF word 106 18 MF word 110 19-32 Repeat word order of bytes 5-18 for subcom level 1 23-46 Repeat word order of bytes 5-18 for

  4. Beta systems error analysis (United States)


    The atmospheric backscatter coefficient, beta, measured with an airborne CO Laser Doppler Velocimeter (LDV) system operating in a continuous wave, focussed model is discussed. The Single Particle Mode (SPM) algorithm, was developed from concept through analysis of an extensive amount of data obtained with the system on board a NASA aircraft. The SPM algorithm is intended to be employed in situations where one particle at a time appears in the sensitive volume of the LDV. In addition to giving the backscatter coefficient, the SPM algorithm also produces as intermediate results the aerosol density and the aerosol backscatter cross section distribution. A second method, which measures only the atmospheric backscatter coefficient, is called the Volume Mode (VM) and was simultaneously employed. The results of these two methods differed by slightly less than an order of magnitude. The measurement uncertainties or other errors in the results of the two methods are examined.

  5. Impact of critical care-trained flight paramedics on casualty survival during helicopter evacuation in the current war in Afghanistan. (United States)

    Mabry, Robert L; Apodaca, Amy; Penrod, Jason; Orman, Jean A; Gerhardt, Robert T; Dorlac, Warren C


    The US Army pioneered medical evacuation (MEDEVAC) by helicopter, yet its system remains essentially unchanged since the Vietnam era. Care is provided by a single combat medic credentialed at the Emergency Medical Technician - Basic level. Treatment protocols, documentation, medical direction, and quality improvement processes are not standardized and vary significantly across US Army helicopter evacuation units. This is in contrast to helicopter emergency medical services that operate within the United States. Current civilian helicopter evacuation platforms are routinely staffed by critical care-trained flight paramedics (CCFP) or comparably trained flight nurses who operate under trained EMS physician medical direction using formalized protocols, standardized patient care documentation, and rigorous quality improvement processes. This study compares mortality of patients with injury from trauma between the US Army's standard helicopter evacuation system staffed with medics at the Emergency Medical Technician - Basic level (standard MEDEVAC) and one staffed with experienced CCFP using adopted civilian helicopter emergency medical services practices. This is a retrospective study of a natural experiment. Using data from the Joint Theater Trauma Registry, 48-hour mortality for severely injured patients (injury severity score ≥ 16) was compared between patients transported by standard MEDEVAC units and CCFP air ambulance units. The 48-hour mortality for the CCFP-treated patients was 8% compared to 15% for the standard MEDEVAC patients. After adjustment for covariates, the CCFP system was associated with a 66% lower estimated risk of 48-hour mortality compared to the standard MEDEVAC system. These findings demonstrate that using an air ambulance system based on modern civilian helicopter EMS practice was associated with a lower estimated risk of 48-hour mortality among severely injured patients in a combat setting.

  6. System of systems modeling and analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, James E.; Anderson, Dennis James; Longsine, Dennis E. (Intera, Inc., Austin, TX); Shirah, Donald N.


    This report documents the results of an LDRD program entitled 'System of Systems Modeling and Analysis' that was conducted during FY 2003 and FY 2004. Systems that themselves consist of multiple systems (referred to here as System of Systems or SoS) introduce a level of complexity to systems performance analysis and optimization that is not readily addressable by existing capabilities. The objective of the 'System of Systems Modeling and Analysis' project was to develop an integrated modeling and simulation environment that addresses the complex SoS modeling and analysis needs. The approach to meeting this objective involved two key efforts. First, a static analysis approach, called state modeling, has been developed that is useful for analyzing the average performance of systems over defined use conditions. The state modeling capability supports analysis and optimization of multiple systems and multiple performance measures or measures of effectiveness. The second effort involves time simulation which represents every system in the simulation using an encapsulated state model (State Model Object or SMO). The time simulation can analyze any number of systems including cross-platform dependencies and a detailed treatment of the logistics required to support the systems in a defined mission.

  7. 77 FR 44116 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters (United States)


    ... degraded the annunciator system's redundant power supply, so that pilots could not be warned of a second...-BK117 C-1 helicopter. The actions of this AD are intended to prevent uncommanded cutting of the hoist... uncommanded cutting of the hoist cable and subsequent injury to persons being lifted by the hoist....

  8. Smart actuation mechanisms for helicopter blades: design case for a mach-scaled model blade

    NARCIS (Netherlands)

    Paternoster, Alexandre


    This work is part of the European project “Clean Sky”, which aims at improving the efficiency and the global transport quality of aircraft. The research, in this project, is currently focussing on active flap systems for helicopters to adapt the blade aerodynamic properties to local aerodynamic

  9. Smart actuation mechanisms for helicopter blades: design case for a mach-scaled model blade

    NARCIS (Netherlands)

    Paternoster, A.R.A.


    This work is part of the European project “Clean Sky”, which aims at improving the efficiency and the global transport quality of aircraft. The research, in this project, is currently focussing on active flap systems for helicopters to adapt the blade aerodynamic properties to local aerodynamic cond

  10. 78 FR 60186 - Airworthiness Directives; AgustaWestland S.p.A. (Agusta) Helicopters (United States)


    ... (AD) for Agusta Model AB139 and AW139 helicopters. This AD requires deactivating the Full Icing Protection System (FIPS) and installing a placard next to the FIPS controller stating that flight into known... views. We also invite comments relating to the economic, environmental, energy, or federalism...

  11. Logical analysis of biological systems

    DEFF Research Database (Denmark)

    Mardare, Radu Iulian


    R. Mardare, Logical analysis of biological systems. Fundamenta Informaticae, N 64:271-285, 2005.......R. Mardare, Logical analysis of biological systems. Fundamenta Informaticae, N 64:271-285, 2005....

  12. Fuzzy logic mode switching in helicopters (United States)

    Sherman, Porter D.; Warburton, Frank W.


    The application of fuzzy logic to a wide range of control problems has been gaining momentum internationally, fueled by a concentrated Japanese effort. Advanced Research & Development within the Engineering Department at Sikorsky Aircraft undertook a fuzzy logic research effort designed to evaluate how effective fuzzy logic control might be in relation to helicopter operations. The mode switching module in the advanced flight control portion of Sikorsky's motion based simulator was identified as a good candidate problem because it was simple to understand and contained imprecise (fuzzy) decision criteria. The purpose of the switching module is to aid a helicopter pilot in entering and leaving coordinated turns while in flight. The criteria that determine the transitions between modes are imprecise and depend on the varied ranges of three flight conditions (i.e., simulated parameters): Commanded Rate, Duration, and Roll Attitude. The parameters were given fuzzy ranges and used as input variables to a fuzzy rulebase containing the knowledge of mode switching. The fuzzy control program was integrated into a real time interactive helicopter simulation tool. Optimization of the heading hold and turn coordination was accomplished by interactive pilot simulation testing of the handling quality performance of the helicopter dynamic model. The fuzzy logic code satisfied all the requirements of this candidate control problem.

  13. Neuroevolutionary reinforcement learning for generalized helicopter control

    NARCIS (Netherlands)

    Koppejan, R.; Whiteson, S.


    Helicopter hovering is an important challenge problem in the field of reinforcement learning. This paper considers several neuroevolutionary approaches to discovering robust controllers for a generalized version of the problem used in the 2008 Reinforcement Learning Competition, in which wind in the

  14. Corrosion potential analysis system (United States)

    Kiefer, Karl F.


    Many cities in the northeastern U.S. transport electrical power from place to place via underground cables, which utilize voltages from 68 kv to 348 kv. These cables are placed in seamless steel pipe to protect the conductors. These buried pipe-type-cables (PTCs) are carefully designed and constantly pressurized with transformer oil to prevent any possible contamination. A protective coating placed on the outside diameter of the pipe during manufacture protects the steel pipe from the soil environment. Notwithstanding the protection mechanisms available, the pipes remain vulnerable to electrochemical corrosion processes. If undetected, corrosion can cause the pipes to leak transformer oil into the environment. These leaks can assume serious proportions due to the constant pressure on the inside of the pipe. A need exists for a detection system that can dynamically monitor the corrosive potential on the length of the pipe and dynamically adjust cathodic protection to counter local and global changes in the cathodic environment surrounding the pipes. The northeastern United States contains approximately 1000 miles of this pipe. This milage is critical to the transportation and distribution of power. So critical, that each of the pipe runs has a redundant double running parallel to it. Invocon, Inc. proposed and tested a technically unique and cost effective solution to detect critical corrosion potential and to communicate that information to a central data collection and analysis location. Invocon's solution utilizes the steel of the casing pipe as a communication medium. Each data gathering station on the pipe can act as a relay for information gathered elsewhere on the pipe. These stations must have 'smart' network configuration algorithms that constantly test various communication paths and determine the best and most power efficient route through which information should flow. Each network station also performs data acquisition and analysis tasks that ultimately

  15. Full-Scale Crash Test of a MD-500 Helicopter with Deployable Energy Absorbers (United States)

    Kellas, Sotiris; Jackson, Karen E.; Littell, Justin D.


    A new externally deployable energy absorbing system was demonstrated during a full-scale crash test of an MD-500 helicopter. The deployable system is a honeycomb structure and utilizes composite materials in its construction. A set of two Deployable Energy Absorbers (DEAs) were fitted on the MD-500 helicopter for the full-scale crash demonstration. Four anthropomorphic dummy occupants were also used to assess human survivability. A demonstration test was performed at NASA Langley's Landing and Impact Research Facility (LandIR). The test involved impacting the helicopter on a concrete surface with combined forward and vertical velocity components of 40-ft/s and 26-ft/s, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of dynamic finite element simulations. Descriptions of this test as well as other component and full-scale tests leading to the helicopter test are discussed. Acceleration data from the anthropomorphic dummies showed that dynamic loads were successfully attenuated to within non-injurious levels. Moreover, the airframe itself survived the relatively severe impact and was retested to provide baseline data for comparison for cases with and without DEAs.

  16. Taper Measurement for Helicopter Rotor Based on Spot Imaging Method%基于光斑成像的直升机旋翼共锥度测量方法

    Institute of Scientific and Technical Information of China (English)

    陆军; 邓超; 蔡成涛; 姜迈


    Helicopter rotor dynamic balancing of rotor taper is an important parameter measurement. It directly affects the performance of helicopter mobility, security and so many key indicators. Rotor rotating at high speed for a state system of measuring the characteristics of taper values, a taper measurement for helicopter rotor based on spot imaging method has been introduced, while a more detailed description of the system, basic structure, basic principle and system error analysis has been introduced. It is a non-contact measurement. It can measure the blade pitch angle beside measuring the rotor taper, and can be realized on a total of helicopter rotor taper high precision measurements. The method has high practical value.%直升机旋翼共锥度值是直升机旋翼动平衡试验中测试的一项重要指标,它关系到直升机的安全和各方面性能,针对在旋翼高速旋转的动态下进行旋翼共锥度测量的特点,设计了一种基于光斑成像的直升机旋翼共锥度测量方法,给出了系统基本构成和测量原理,并进行了系统误差分析;该方法是一种非接触式的测量方法,在测量旋翼锥度差的同时,还可以测出桨叶的桨距角,可实现对直升机旋翼共锥度较高精度的测量;该方法具有较高的实际应用价值.

  17. Active structural acoustic control of helicopter interior multifrequency noise using input-output-based hybrid control (United States)

    Ma, Xunjun; Lu, Yang; Wang, Fengjiao


    This paper presents the recent advances in reduction of multifrequency noise inside helicopter cabin using an active structural acoustic control system, which is based on active gearbox struts technical approach. To attenuate the multifrequency gearbox vibrations and resulting noise, a new scheme of discrete model predictive sliding mode control has been proposed based on controlled auto-regressive moving average model. Its implementation only needs input/output data, hence a broader frequency range of controlled system is modelled and the burden on the state observer design is released. Furthermore, a new iteration form of the algorithm is designed, improving the developing efficiency and run speed. To verify the algorithm's effectiveness and self-adaptability, experiments of real-time active control are performed on a newly developed helicopter model system. The helicopter model can generate gear meshing vibration/noise similar to a real helicopter with specially designed gearbox and active struts. The algorithm's control abilities are sufficiently checked by single-input single-output and multiple-input multiple-output experiments via different feedback strategies progressively: (1) control gear meshing noise through attenuating vibrations at the key points on the transmission path, (2) directly control the gear meshing noise in the cabin using the actuators. Results confirm that the active control system is practical for cancelling multifrequency helicopter interior noise, which also weakens the frequency-modulation of the tones. For many cases, the attenuations of the measured noise exceed the level of 15 dB, with maximum reduction reaching 31 dB. Also, the control process is demonstrated to be smoother and faster.

  18. The Acoustic Signal of a Helicopter can be Used to Track it With Seismic Arrays (United States)

    Eibl, Eva P. S.; Lokmer, Ivan; Bean, Christopher J.; Akerlie, Eggert


    We apply traditional frequency domain methods usually applied to volcanic tremor on seismic recordings of a helicopter. On a volcano the source can be repeating, closely spaced earthquakes whereas for a helicopter the source are repeating pressure pulses from the rotor blades that are converted through acoustic-to-seismic coupling. In both cases the seismic signal is referred to as tremor. As frequency gliding is in this case merely caused by the Doppler effect, not a change in the source, we can use its shape to deduce properties of the helicopter. We show in this analysis that the amount of rotor blades, rotor revolutions per minute (RPM), flight direction, height and location can be deduced. The signal was recorded by a seven station broadband array with an aperture of 1.6 km. Our spacing is close enough to record the signal at all stations and far enough to observe traveltime differences. We perform a detailed spectral and location analysis of the signal, and compare our results with the known information on the helicopter's speed, location, height, the frequency of the blades rotation and the amount of blades. This analysis is based on the characteristic shape of the curve i.e. speed of the gliding, minimum and maximum fundamental frequency, amplitudes at the inflection points at different stations and traveltimes deduced from the inflection points at different stations. The helicopter GPS track gives us a robust way of testing the method. This observation has an educative value, because the same principles can be applied to signals in different disciplines.

  19. Mortality following helicopter versus ground transport of injured children. (United States)

    Polites, Stephanie F; Zielinski, Martin D; Fahy, Aodhnait S; Wagie, Amy E; Moir, Christopher R; Jenkins, Donald H; Zietlow, Scott P; Habermann, Elizabeth B


    Injured children may be transported to trauma centers by helicopter air ambulance (HAA); however, a benefit in outcomes to this expensive resource has not been consistently shown in the literature and there is concern that HAA is over-utilized. A study that adequately controls for selection biases in transport mode is needed to determine which injured children benefit from HAA. The purpose of this study was to determine if HAA impacts mortality differently in minimally and severely injured children and if there are predictors of over-triage of HAA in children that can be identified. Children ≤18 years of age transported by HAA or ground ambulance (GA) from scene to a trauma center were identified from the 2010-2011 National Trauma Data Bank. Analysis was stratified by Injury Severity Score (ISS) into low ISS (≤15) and high ISS (>15) groups. Following propensity score matching of HAA to GA patients, conditional multivariable logistic regression was performed to determine if transport mode independently impacted mortality in each stratum. Rates and predictors of over-triage of HAA were also determined. Transport by HAA occurred in 8218 children (5574 low ISS, 2644 high ISS) and by GA in 35305 (30506 low ISS, 4799 high ISS). Overall mortality was greater in HAA patients (4.0 vs 1.4%, p15. Many children with minor injuries are transported by helicopter despite frequent dismissal within 24h and no mortality benefit. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. The helicopter dynamic stability analysis in hover condition using magneto-rheological dampers%悬停状态带磁流变减摆器直升机的动稳定性分析

    Institute of Scientific and Technical Information of China (English)

    卫丽君; 李书


    Magneto-rheological damper model suitable for helicopter air resonance and momentum theory model of hover condition involving momentum theory were built in this paper. The equations of the two models with the dynamic equations of helicopter rotor/body coupling were solved by Simulink time domain simulation method to obtain the helicopter dynamic stability influenced by Magneto-rheological damper and compared the blade flapping and lagging impacted by Magneto-rheological dampers under different voltages. It could be conclude that under a certain voltage, Magneto-rheological damper was not influenced by duel-frequent excitation, and was good at restraining the helicopter air resonance.%建立了适用于直升机悬停状态动稳定性的磁流变减摆器模型,悬停状态下动力入流模型采用动量理论模型,与直升机旋翼/机体耦合动力学方程组联立,采用Simulink时域仿真的方法计算得到磁流变减摆器对悬停状态下直升机动稳定的影响,对比了不同电压下磁流变减摆器对桨叶挥舞摆振运动的影响.结果表明:对于磁流变减摆器,施加不同电压可得到不同的阻尼力,该性质可以抑制直升机悬停状态动不稳定性.

  1. 舰载与陆基直升机飞行员健康影响因素调查分析%Investigation Analysis of Influential Factors of Health of Seabased and Landbased Helicopter Pilots

    Institute of Scientific and Technical Information of China (English)

    刘浩; 张佳丽; 李鸣皋


    Objective To analyze the influential factors of health of seabased and landbased helicopter pilots to guide health service strategy. Methods The values of body mass index ( BMI) , diet, exercise frequency, sleep quality, incidence rates of flight illusion and motion sickness, and flying confidence in 31 seabased helicopter pilots ( group A) and 557 landbased helicopter pilots ( group B) were compared and analyzed based on the health questionnaire results. Results Compared with those in group B, in the group A the values of sleep quality and exercise frequency were signifi-cantly lower (P  与陆基飞行员组比较,舰载飞行员组睡眠质量较差、锻炼较少(P0.05)。结论睡眠、锻炼、飞行信心是舰载机飞行员健康的影响因素,且严重影响飞行能力,应加强这一特殊群体的睡眠、体能管理及心理干预。

  2. 78 FR 16200 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ..., AS355F1, AS355F2, AS355N, and AS355NP helicopters with either an autopilot or certain modifications..., AS350B2, AS350C, AS350D, AS350D1, AS355E, AS355F, AS355F1, and AS355F2 helicopters with an autopilot installed; (2) Model AS350B3 helicopters with an autopilot or modification 073252 installed; and (3)...

  3. Feasibility of a Nap-of-the-Earth Trainer Using a QH-50D Remotely Piloted Helicopter and Synthetic Flight Training System (United States)


    time is as great as the available flight time. If two QH-50Ds are available for each SFTS, then one can be going through post- and preflight...and in previous programs is that the ground preparation time is as great as the available flight time (see Appendix A). If two QH-SODs are available...Alabama. 3. Kaplan, Devid H., "The ’Guide Lite’ System", Control Instrument Division, Defense and Space Group, Burroughs Corporation, Paoli, Pennsylvania

  4. Systems analysis made simple computerbooks

    CERN Document Server

    Antill, Lyn


    Systems Analysis: Made Simple Computerbooks introduces the essential elements of information systems analysis and design and teaches basic technical skills required for the tasks involved. The book covers the aspects to the design of an information system; information systems and the organization, including the types of information processing activity and computer-based information systems; the role of the systems analyst; and the human activity system. The text also discusses information modeling, socio-technical design, man-machine interface, and the database design. Software specification

  5. Pilot ejection, parachute, and helicopter crash injuries. (United States)

    McBratney, Colleen M; Rush, Stephen; Kharod, Chetan U


    USAF Pararescuemen (PJs) respond to downed aircrew as a fundamental mission for personnel recovery (PR), one of the Air Force's core functions. In addition to responding to these in Military settings, the PJs from the 212 Rescue Squadron routinely respond to small plane crashes in remote regions of Alaska. While there is a paucity of information on the latter, there have been articles detailing injuries sustained from helicopter crashes and while ejecting or parachuting from fixed wing aircraft. The following represents a new chapter added to the Pararescue Medical Operations Handbook, Sixth Edition (2014, editors Matt Wolf, MD, and Stephen Rush, MD, in press). It was designed to be a quick reference for PJs and their Special Operations flight surgeons to help with understanding of mechanism of injury with regard to pilot ejection, parachute, and helicopter accident injuries. It outlines the nature of the injuries sustained in such mishaps and provides an epidemiologic framework from which to approach the problem. 2014.

  6. Helicopter crew/passenger vibration sensitivity - (United States)

    Gabel, R.; Reed, D. A.


    Helicopter crew and passenger vibration sensitivity are presented. Pilot subjective ratings are established for discrete frequencies and the impact of combinations of harmonic frequencies is examined. A passenger long term comfort level and a short term limit are defined for discrete frequencies and compared with pilot ratings. The results show reasonable agreement between pilot and passenger. Subjective comfort levels obtained for mixed frequency environments clearly demonstrate the need for a multi-frequency criterion.

  7. Detection And Avoidance Of Obstacles By Helicopters (United States)

    Cheng, Victor H. L.; Sridhar, Banavar


    Report discusses problems relevant to control subsystems enabling helicopters on nap-of-the-Earth flight paths to detect and avoid obstacles automatically. Indicates similarities between this and obstacle-avoidance problem of industrial mobile robots. Two approaches extend two-dimensional obstacle-avoidance concept to three dimensions. First involves direct search of three-dimensional range-map data for indications of openings between obstacles. Second involves compression of data into two-dimensional map for path search.

  8. Stabilization of Externally Slung Helicopter Loads (United States)


    maximum slir^ Loao weighting and " vertical bounce ." The last question provides information on multi-point suspension of external 1oads. allowable cargo load, and vertical bounce . 110 Maximum Sling Load Weight The maximum sling load lifted by a CH-47B helicopter under...changes were made in their flying technique except for very smooth flight control inputs when lifting an ACL. Vertical Bounce Fifteen of the forty Army

  9. Hearing loss in civilian airline and helicopter pilots compared to air traffic control personnel. (United States)

    Wagstaff, Anthony S; Arva, Per


    In order to investigate possible hearing loss as a consequence of aviation noise, a comparative analysis of audiometric data from Norwegian Air Traffic Control (ATC) personnel, airline (fixed-wing) pilots, and helicopter pilots was performed. The results may be of use in giving advice regarding preventive measures. Male ATC, airline, and helicopter pilots were selected randomly from the Civil Aviation Authority (CAA) medical files. There were 182 subjects included in the study: 50, 81, and 51 subjects for ATC, helicopter, and airline pilots, respectively. Two audiograms with a 2-3-yr interval were analyzed for each individual. Age correction was performed using data from ISO 7129. Threshold changes per year for the frequencies 3, 4, and 6 kHz were examined in particular after age correction. For all three groups, mean hearing threshold levels were above (worse than) ISO 7129 predictions for most frequencies. As expected, hearing thresholds increased with age in the group as a whole. Looking at the 3-, 4-, and 6-kHz frequencies in particular, all groups had small but highly significant increases in hearing thresholds at 4 kHz between the first and second audiogram. The mean hearing thresholds for this group of aviation personnel are higher than International Standard ISO-7129 would predict according to age. Highly significant changes in hearing threshold after age correction, indicating possible noise-induced hearing loss, were found in all groups at 4 kHz. The fact that helicopter pilots had similar hearing loss to their other aviation colleagues indicates that current hearing protection for these pilots is effective in counteracting the increased noise levels in helicopters.

  10. The Study of the Application to the Low-Altitude Remote Sensing System Based on Light Helicopter for the Flight Platform%基于轻型直升机为飞行平台的低空遥感系统应用研究

    Institute of Scientific and Technical Information of China (English)



    利用轻型直升机为飞行平台,搭载以全姿态纠正云台为核心的低空航摄设备进行试验研究,研发制造了相应的减震设备,有效地消除了直升机旋翼振动的影响.通过试验证明了该系统能够满足大比例尺成图的精度要求.在我国山区具有很好的推广价值.%Using light helicopter as flying platform, equipped with low - altitude aerial photograph equipment centered on all - attitude correction tripod head for the purpose of pilot study, this paper develops the respective vibration damping device, effectively eliminate the impact of helicopter rotor vibration. It is proved by experiment that the system can meet the accuracy requirements of large - scale mapping, which is valuable if applied in mountainous regions.

  11. Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction (United States)

    Straub, F. K.; Byrns, E. V., Jr.


    The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism.

  12. Blind source separation of helicopter vibration signal based on improved particle swarm algorithm%基于改进粒子群算法的直升机振动信号盲分离

    Institute of Scientific and Technical Information of China (English)

    申江江; 高峰; 曲建岭; 袁涛; 刘锦涛


    振动信号分析是直升机状态监控的重要研究内容之一。针对某型直升机加装的振动信号采集系统,提出一种基于改进粒子群优化算法(PSO)的盲源分离方法。介绍了盲源分离(BSS)基本理论及改进的基于动态因子的粒子群优化算法,将二者结合应用于某型直升机振动信号盲分离研究。仿真实验及噪声中实测直升机振动信号的盲分离都取得了良好的分离效果,结果表明相比于直接使用FastICA方法,所提出的方法具有分离精度高、迭代次数少等优点。%Vibration signal analysis is one of significant research contents for helicopter condition monitoring. Aiming at the vibration signal acquisition system installed a helicopter,a blind source separation (BSS )method based on improved particle swarn optimization (PSO)is proposed.BSS basic theory and improved PSO based on dynamic factor are introduced,and they are combined and put into BSS research of helicopter vibration signal.The blind source separation of simulation experiment and real-acquainted helicopter vibration signals in noise environment obtains good separation result.And compared with using FastICA directly,the result shows that this algorithm proposed in this paper has advantages of high precision and less iteration times.

  13. Systems Engineering Analysis

    Directory of Open Access Journals (Sweden)

    Alexei Serna M.


    Full Text Available The challenges proposed by the development of the new computer systems demand new guidance related to engineer´s education, because they will solve these problems. In the XXI century, system engineers must be able to integrate a number of topics and knowledge disciplines that complement that traditionally has been known as Computer Systems Engineering. We have enough software development engineers, today we need professional engineers for software integration, leaders and system architects that make the most of the technological development for the benefit of society, leaders that integrate sciences to the solutions they build and propose. In this article the current situation of Computer Systems Engineering is analyzed and is presented a theory proposing the need for modifying the approach Universities have given to these careers, to achieve the education of leader engineers according to the needs of this century.

  14. Energy Usage Analysis System (United States)

    General Services Administration — The EUAS application is a web based system which serves Energy Center of Expertise, under the Office of Facilitates Management and Service Programs. EUAS is used for...

  15. 76 FR 20490 - Special Conditions: Eurocopter France Model AS350B Series, AS350D, and EC130 Helicopters... (United States)


    ..., AS350D, and EC130 Helicopters, Installation of a Hoh Aeronautics, Inc. Autopilot/Stabilization...) complex autopilot/stabilization augmentation system (AP/SAS) that has potential failure conditions with... autopilot/stabilization augmentation system (AP/ SAS) on the Eurocopter model AS350B, AS350BA,...

  16. A comparative study and application of continuously variable transmission to a single main rotor heavy lift helicopter (United States)

    Hameer, Sameer

    operating speeds. The analysis of the split torque type P-CVT achieved a weight reduction of 42.5% and 40.7% over planetary and split torque transmissions respectively. In addition, a 19.5 dB sound pressure level reduction was achieved using active gear struts, and also the use of fabricated steel truss like housing provided a higher maintainability and reliability, low cost, and low weight over cast magnesium housing currently employed in helicopters. The static finite element analysis of the split torque type P-CVT, both 2-D and 3-D, yielded stresses below the allowable bending stress of the material. The goal of the finite element analysis is to see if the designed product has met its functional requirements. The safety assessment of the split torque type P-CVT yielded a 99% probability of mission success based on a Monte Carlo simulation using stochastic-petri net analysis and a failure hazard analysis. This was followed by an FTA/RBD analysis which yielded an overall system failure rate of 140.35 failures per million hours, and a preliminary certification and time line of certification was performed. The use of spherical facegears and pericyclic kinematics has advanced the state of the art in drivetrain design primarily in the reduction of weight and noise coupled with high safety, reliability, and efficiency.

  17. Helicopter thermal imaging for detecting insect infested cadavers. (United States)

    Amendt, Jens; Rodner, Sandra; Schuch, Claus-Peter; Sprenger, Heinz; Weidlich, Lars; Reckel, Frank


    One of the most common techniques applied for searching living and even dead persons is the FLIR (Forward Looking Infrared) system fixed on an aircraft like e.g. a helicopter, visualizing the thermal patterns emitted from objects in the long-infrared spectrum. However, as body temperature cools down to ambient values within approximately 24h after death, it is common sense that searching for deceased persons can be just applied the first day post-mortem. We postulated that the insect larval masses on a decomposing body generate a heat which can be considerably higher than ambient temperatures for a period of several weeks and that such heat signatures might be used for locating insect infested human remains. We examined the thermal history of two 70 and 90kg heavy pig cadavers for 21days in May and June 2014 in Germany. Adult and immature insects on the carcasses were sampled daily. Temperatures were measured on and inside the cadavers, in selected maggot masses and at the surroundings. Thermal imaging from a helicopter using the FLIR system was performed at three different altitudes up to 1500ft. during seven day-flights and one night-flight. Insect colonization was dominated by blow flies (Diptera: Calliphoridae) which occurred almost immediately after placement of the cadavers. Larvae were noted first on day 2 and infestation of both cadavers was enormous with several thousand larvae each. After day 14 a first wave of post-feeding larvae left the carcasses for pupation. Body temperature of both cadavers ranged between 15°C and 35°C during the first two weeks of the experiment, while body surface temperatures peaked at about 45°C. Maggot masses temperatures reached values up to almost 25°C above ambient temperature. Detection of both cadavers by thermal imaging was possible on seven of the eight helicopter flights until day 21. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

  18. Active vibration attenuating seat suspension for an armored helicopter crew seat (United States)

    Sztein, Pablo Javier

    An Active Vibration Attenuating Seat Suspension (AVASS) for an MH-60S helicopter crew seat is designed to protect the occupants from harmful whole-body vibration (WBV). Magnetorheological (MR) suspension units are designed, fabricated and installed in a helicopter crew seat. These MR isolators are built to work in series with existing Variable Load Energy Absorbers (VLEAs), have minimal increase in weight, and maintain crashworthiness for the seat system. Refinements are discussed, based on testing, to minimize friction observed in the system. These refinements include the addition of roller bearings to replace friction bearings in the existing seat. Additionally, semi-active control of the MR dampers is achieved using special purpose built custom electronics integrated into the seat system. Experimental testing shows that an MH-60S retrofitted with AVASS provides up to 70.65% more vibration attenuation than the existing seat configuration as well as up to 81.1% reduction in vibration from the floor.

  19. Terrain and Radiation Mapping in Post-Disaster Environments Using an Autonomous Helicopter

    Directory of Open Access Journals (Sweden)

    Kevin Kochersberger


    Full Text Available Recent events have highlighted the need for unmanned remote sensing in dangerous areas, particularly where structures have collapsed or explosions have occurred, to limit hazards to first responders and increase their efficiency in planning response operations. In the case of the Fukushima nuclear reactor explosion, an unmanned helicopter capable of obtaining overhead images, gathering radiation measurements, and mapping both the structural and radiation content of the environment would have given the response team invaluable data early in the disaster, thereby allowing them to understand the extent of the damage and areas where dangers to personnel existed. With this motivation, the Unmanned Systems Lab at Virginia Tech has developed a remote sensing system for radiation detection and aerial imaging using a 90 kg autonomous helicopter and sensing payloads for the radiation detection and imaging operations. The radiation payload, which is the sensor of focus in this paper, consists of a scintillating type detector with associated software and novel search algorithms to rapidly and effectively map and locate sources of high radiation intensity. By incorporating this sensing technology into an unmanned aerial vehicle system, crucial situational awareness can be gathered about a post-disaster environment and response efforts can be expedited. This paper details the radiation mapping and localization capabilities of this system as well as the testing of the various search algorithms using simulated radiation data. The various components of the system have been flight tested over a several-year period and a new production flight platform has been built to enhance reliability and maintainability. The new system is based on the Aeroscout B1-100 helicopter platform, which has a one-hour flight endurance and uses a COFDM radio system that gives the helicopter an effective range of 7 km.

  20. Land suitability for establishing rainwater harvesting systems for fighting wildfires (United States)

    José María León Villalobos; Manuel Anaya Garduño; Enrique Ojeda Trejo; Dante Arturo Rodríguez Trejo; José Luis Oropeza Mota; Jorge Luis García Rodríguez


    Rainwater harvesting systems (RHSs) can be used to improve the efficiency of helicopter firefighting operations. To this end, RHSs need to be strategically located in areas with high wildfire occurrence to maximize their usefulness. In this study, spatial analysis was carried out to determine suitable sites for establishing RHSs intended for air attack operations in...

  1. 78 FR 44043 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... unsafe condition is likely to exist or develop on other products of the same type design. Related Service....3 Flight Envelope, Item 2 Temperature Limits, of the helicopter's Rotorcraft Flight Manual (RFM... Operating Limitations Section of the helicopter's Rotorcraft Flight Manual (RFM) by making pen and...

  2. Power harvesting using piezoelectric materials: applications in helicopter rotors

    NARCIS (Netherlands)

    Jong, de P.H.


    The blades of helicopters are heavily loaded and are critical components. Failure of any one blade will lead to loss of the aircraft. Currently, the technical lifespan of helicopter blades is calculated using a worst-case operation scenario. The consequence is that a blade that may be suitable for,

  3. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.


    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for understandi

  4. Helicopter Emergency Medical Services: effects, costs and benefits

    NARCIS (Netherlands)

    A.N. Ringburg (Akkie)


    textabstractAdvanced prehospital medical care with air transport was introduced in the Netherlands in May 1995. The fi rst helicopter Mobile Medical Team, also called Helicopter Emergency Medical Service (HEMS) was a joint venture initiative of the VU Medical Center in Amsterdam and the Algemene Ned

  5. 77 FR 54796 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... 26, 2010, which specifies installing two siliconed glass wool sleeves over both forward main rotor... the continued airworthiness of these helicopters. ] Costs of Compliance We estimate that this AD will.... Required parts cost $212, for a total cost of $297 for each helicopter. Based upon these costs, we...

  6. Model Tests on the Economy and Effectiveness of Helicopter Propellers (United States)

    Munk, Max M


    The average velocity of helicopter blades relative to the air is greater than that of airplane wings. The helicopter may turn out to be more economical than the airplane wing for extreme velocities of horizontal flight, the airplane then requiring a very great speed range.

  7. 78 FR 59298 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... pilot of a Eurocopter Model AS350 helicopter felt slight vibrations in the pedal unit in flight. A few minutes later, the vibration level increased and the pilot carried out a precautionary autorotation... neutral position. If the helicopter is fitted with a T/R load compensator, discharge the accumulator...

  8. 77 FR 58925 - Airworthiness Directives; Eurocopter France Helicopters (United States)


    ... during an inspection of a Model AS- 365 helicopter equipped with a 10-blade TRH. This AD requires... likely to exist or develop on other helicopters of these same type designs. Related Service Information... of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures...

  9. Sleep and Alertness in North Sea Helicopter Operations

    NARCIS (Netherlands)

    Simons, M.; Wilschut, E.S.; Valk, P.J.L.


    Introduction : Dutch North Sea helicopter operations are characterized by multiple sector flights to offshore platforms under difficult environmental conditions. In the context of a Ministry of Transport program to improve safety levels of helicopter operations, we assessed effects of pre-duty


    Institute of Scientific and Technical Information of China (English)


    Vibration suppression is one of the most important tasks for helicopter research. ACSR (Active Control of Structural Response) in time domain has turned out to be an effective technique to deal with this issue. In this paper, based on Least Square Principle and ACSR Principle, a multichannel delayed filtered-x FTF (Fast Transversal Filter) algorithm is developed for suppressing helicopter vibration. In order to keep the algorithm running in a stable and efficient state, DRR (Desired Response Reconstruction) technique is developed and a Constraint Stabilization Technique is firstly presented for the developed algorithm. Computer simulations are conducted on attenuating helicopter vibration and remarkable vibration reductions are achieved. The results demonstrate good properties of the obtained FTF algorithm in stability, robustness, convergence speed, tracking capability, etc.. They also show that time delay and DRR technique play important and effective roles in keeping ACSR system working efficiently.

  11. Advances in transitional flow modeling applications to helicopter rotors

    CERN Document Server

    Sheng, Chunhua


    This book provides a comprehensive description of numerical methods and validation processes for predicting transitional flows based on the Langtry–Menter local correlation-based transition model, integrated with both one-equation Spalart–Allmaras (S–A) and two-equation Shear Stress Transport (SST) turbulence models. A comparative study is presented to combine the respective merits of the two coupling methods in the context of predicting the boundary-layer transition phenomenon from fundamental benchmark flows to realistic helicopter rotors. The book will of interest to industrial practitioners working in aerodynamic design and the analysis of fixed-wing or rotary wing aircraft, while also offering advanced reading material for graduate students in the research areas of Computational Fluid Dynamics (CFD), turbulence modeling and related fields.

  12. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage

    Directory of Open Access Journals (Sweden)

    Kusyumov A.N.


    Full Text Available The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman’s approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.

  13. Subjective assessment of simulated helicopter blade-slap noise (United States)

    Lawton, B. W.


    The effects of several characteristics of helicopter blade slap upon human annoyance are examined. Blade slap noise was simulated by using continuous and impulsive noises characterized by five parameters: The number of sine waves in a single impulse; the frequency of the sine waves; the impulse repetition frequency; the sound pressure level (SPL) of the continuous noise; and the idealized crest factor of the impulses. Ten second samples of noise were synthesized with each of the five parameters at representative levels. The annoyance of each noise was judged by 40 human subjects. Analysis of the subjective data indicated that each of the five parameters had a statistically significant effect upon the annoyance judgments. The impulse crest factor and SPL of the continuous noise had very strong positive relationships with annoyance. The other parameters had smaller, but still significant, effects upon the annoyance judgments.

  14. Helicopter Night Vision System Simulation Evaluation (United States)


    mision safety. The enroute evaluation indicates a con- sistent preference for the 4HMD-PMD configuration. The copilot felt that the virtual HUD...pilot but never allowed Cho copilot to slow in a hover. In edsencer the night cranpore mision appears wo be a two pilot task with a t consant verbal

  15. A Simplified Mobile Ad Hoc Network Structure for Helicopter Communication

    Directory of Open Access Journals (Sweden)

    Abdeldime Mohamed Salih Abdelgader


    Full Text Available There are a number of volunteer and statutory organizations who are capable of conducting an emergency response using helicopters. Rescue operations require a rapidly deployable high bandwidth network to coordinate necessary relief efforts between rescue teams on the ground and helicopters. Due to massive destruction and loss of services, ordinary communication infrastructures may collapse in these situations. Consequently, information exchange becomes one of the major challenges in these circumstances. Helicopters can be also employed for providing many services in rugged environments, military applications, and aerial photography. Ad hoc network can be used to provide alternative communication link between a set of helicopters, particularly in case of significant amount of data required to be shared. This paper addresses the ability of using ad hoc networks to support the communication between a set of helicopters. A simplified network structure model is presented and extensively discussed. Furthermore, a streamlined routing algorithm is proposed. Comprehensive simulations are conducted to evaluate the proposed routing algorithm.

  16. Effectiveness of helicopter versus ground ambulance services for interfacility transport. (United States)

    Arfken, C L; Shapiro, M J; Bessey, P Q; Littenberg, B


    Helicopters provide rapid interfacility transport, but the effect on patients is largely unknown. Patients requested to be transported between facilities by helicopter were followed prospectively to determine survival, disability, health status, and health care utilization. A total of 1,234 patients were transported by the primary aeromedical company; 153 patients were transported by ground and 25 patients were transported by other aeromedical services because of weather or unavailability of aircraft. There were no differences at 30 days for survivors in disability, health status, or health care utilization. Nineteen percent of helicopter-transported patients died compared with 15% of those transported by ground (p=0.21). The patients transported by helicopter did not have improved outcomes compared with patients transported by ground. These data argue against a large advantage of helicopters for interfacility transport. A randomized trial is needed to address these issues conclusively.

  17. Dynamics of a split torque helicopter transmission. M.S. Thesis - Cleveland State Univ. (United States)

    Krantz, Timothy L.


    Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

  18. 75 FR 5681 - Airworthiness Directives; Bell Helicopter Textron, Inc. Model 205B and 212 Helicopters (United States)


    ..., Rotorcraft Directorate, Rotorcraft Certification Office, 2601 Meacham Blvd., Fort Worth, Texas 76137... condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD is... 39.19. Contact the Manager, Rotorcraft Certification Office, ATTN: Michael Kohner, Aviation...

  19. 78 FR 56148 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters (United States)


    ...-2009-32, dated July 24, 2009, issued by Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, to correct an unsafe condition for the specified Bell model ] helicopters. TCCA... operation in the United States. Pursuant to our bilateral agreement with Canada, TCCA has notified us of...

  20. 77 FR 5423 - Airworthiness Directives; Bell Helicopter Textron Canada, Limited (Bell) Helicopters (United States)


    ... turbine outlet temperature (TOT) indicator over-temperature warning light, when illuminated, created glare... while using night vision goggles and to prevent subsequent loss of control of the helicopter. DATES: We.... Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New...

  1. 77 FR 36389 - Airworthiness Directives; Bell Helicopter Textron Canada, Limited, Helicopters (United States)


    ... over-temperature warning light, when illuminated, created glare and reflections that could degrade the... prevent subsequent loss of control of the helicopter. DATES: This AD is effective July 24, 2012. ADDRESSES..., Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. Examining the AD Docket: You may...

  2. 75 FR 62639 - Air Ambulance and Commercial Helicopter Operations, Part 91 Helicopter Operations, and Part 135... (United States)


    ...--Nautical mile NTSB--National Transportation Safety Board NVG--Night vision goggles NVIS--Night-vision... ambulances have varying situational- awareness technology (such as night vision goggles, HTAWS, radio... during night conditions as four common factors in helicopter air ambulance accidents. A review...

  3. Grey Repairable System Analysis

    Institute of Scientific and Technical Information of China (English)

    Renkuan Guo; Charles Ernie Love


    In this paper, we systematically discuss the basic concepts of grey theory, particularly the grey differential equation and its mathematical foundation, which is essentially unknown in the reliability engineering community. Accordingly,we propose a small-sample based approach to estimate repair improvement effects by partitioning system stopping times into intrinsic functioning times and repair improvement times. An industrial data set is used for illustrative purposes in a stepwise manner.

  4. Arctic Climate Systems Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ivey, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robinson, David G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boslough, Mark B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Backus, George A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Peterson, Kara J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); van Bloemen Waanders, Bart G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Swiler, Laura Painton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Desilets, Darin Maurice [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reinert, Rhonda Karen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    This study began with a challenge from program area managers at Sandia National Laboratories to technical staff in the energy, climate, and infrastructure security areas: apply a systems-level perspective to existing science and technology program areas in order to determine technology gaps, identify new technical capabilities at Sandia that could be applied to these areas, and identify opportunities for innovation. The Arctic was selected as one of these areas for systems level analyses, and this report documents the results. In this study, an emphasis was placed on the arctic atmosphere since Sandia has been active in atmospheric research in the Arctic since 1997. This study begins with a discussion of the challenges and benefits of analyzing the Arctic as a system. It goes on to discuss current and future needs of the defense, scientific, energy, and intelligence communities for more comprehensive data products related to the Arctic; assess the current state of atmospheric measurement resources available for the Arctic; and explain how the capabilities at Sandia National Laboratories can be used to address the identified technological, data, and modeling needs of the defense, scientific, energy, and intelligence communities for Arctic support.

  5. Neck and shoulder muscle activity and posture among helicopter pilots and crew-members during military helicopter flight

    DEFF Research Database (Denmark)

    Murray, Mike; Lange, Britt; Chreiteh, Shadi Samir


    Neck pain among helicopter pilots and crew-members is common. This study quantified the physical workload on neck and shoulder muscles using electromyography (EMG) measures during helicopter flight. Nine standardized sorties were performed, encompassing: cruising from location A to location B (AB...

  6. 直升机气动噪声研究进展%Progress in aero-acoustic technology of helicopter

    Institute of Scientific and Technical Information of China (English)

    陈平剑; 仲唯贵; 段广战


    The status and progress in helicopter aero-acoustic technology is presented,inclu-ding test technology,analysis method and rotor noise control technology.The advanced test technologies such as unsteady pressure measurement,flow field visualization and noise source lo-calization,have been implemented in the acoustic wind tunnel test of rotor noise,which is the es-sential instrument for helicopter aero-acoustic research.Flight test of helicopter aero-acoustic measurements has become a necessary technique in the programs of helicopter noise certification and helicopter noise reduction investigation.With the development of helicopter aero-acoustic noise analysis method,many software tools for rotor noise prediction have been developed and applied in the helicopter design and noise reduction research,based on the solutions of the FW-H equation and Kirchhoff equation.Low noise blade tip is the primary and effective method for heli-copter noise control,and is used widely in helicopter design.Moreover,new technologies such as noise abatement operation and active rotor noise control have been validated by flight test,but have not been used in helicopter design get.Initiated by the demands to design environmentally compatible helicopter,both societies of industry and academia will devote more effort in helicop-ter aero-acoustic technology research.%对直升机气动噪声的研究进展进行了综述,内容包括试验技术、理论分析方法和噪声抑制技术。声学风洞试验是直升机气动噪声研究的基本手段,其中非定常载荷测试、流场显示和声源定位等先进测试技术已实现应用;飞行试验在直升机噪声适航标准完善和噪声控制技术研究等方面已成为必不可少的研究和验证手段。直升机气动噪声的理论体系不断完善,包括声类比法、Kirchhoff/CFD 混合法等旋翼气动噪声分析方法都已形成分析程序,成为直升机研发的有效工具。直升机气动噪声

  7. Quantitative thermoelastic measurement on a helicopter glass fibre component underneath a surface anti-fretting coating.

    Directory of Open Access Journals (Sweden)

    Costa A.


    Full Text Available Thermoelastic stress analysis (TSA has been applied to measure the first stress invariant on a composite helicopter component under load. The component comprised inner mono-directional glass fiber layers with an outer central plate in glass fiber cloth, covered by an anti-fretting surface coating. In order to obtain quantitative results, a previous calibration of the thermoelastic constant obtained on a composite sample with a similar anti-fretting coating has been necessary.

  8. Selected Methods for Locking Screw Joints, Including the Use of Adhesives, Used in the Helicopter Construction (United States)

    Rudawska, Anna; Cisz, Sławomir; Warda, Tomasz


    The paper presents the problems of preventing screw joints from self-loosening on one of helicopter. The research examines selected locking methods used in aircraft produced by different manufacturers. Experimental tests were performed to investigate the loosening torque of screw joints locked by various devices: cotter pin, locknut, centre punching, self-locking nut and adhesive. A comparative analysis of the investigated locking methods is made with respect to their locking strength and efficiency.

  9. Systems analysis-independent analysis and verification

    Energy Technology Data Exchange (ETDEWEB)

    Badin, J.S.; DiPietro, J.P. [Energetics, Inc., Columbia, MD (United States)


    The DOE Hydrogen Program is supporting research, development, and demonstration activities to overcome the barriers to the integration of hydrogen into the Nation`s energy infrastructure. Much work is required to gain acceptance of hydrogen energy system concepts and to develop them for implementation. A systems analysis database has been created that includes a formal documentation of technology characterization profiles and cost and performance information. Through a systematic and quantitative approach, system developers can understand and address important issues and thereby assure effective and timely commercial implementation. This project builds upon and expands the previously developed and tested pathway model and provides the basis for a consistent and objective analysis of all hydrogen energy concepts considered by the DOE Hydrogen Program Manager. This project can greatly accelerate the development of a system by minimizing the risk of costly design evolutions, and by stimulating discussions, feedback, and coordination of key players and allows them to assess the analysis, evaluate the trade-offs, and to address any emerging problem areas. Specific analytical studies will result in the validation of the competitive feasibility of the proposed system and identify system development needs. Systems that are investigated include hydrogen bromine electrolysis, municipal solid waste gasification, electro-farming (biomass gasifier and PEM fuel cell), wind/hydrogen hybrid system for remote sites, home electrolysis and alternate infrastructure options, renewable-based electrolysis to fuel PEM fuel cell vehicle fleet, and geothermal energy used to produce hydrogen. These systems are compared to conventional and benchmark technologies. Interim results and findings are presented. Independent analyses emphasize quality, integrity, objectivity, a long-term perspective, corporate memory, and the merging of technical, economic, operational, and programmatic expertise.

  10. Recent Ice thickness helicopter borne radar surveys in Patagonia (United States)

    Rivera, Andres; Zamora, Rodrigo; Andres Uribe, Jose; Oberreuter, Jonathan; Gacitua, Guisella; Rignot, Eric


    The Patagonian icefields are the biggest temperate ice bodies in southern hemisphere, which have experienced important areal shrinkage and thinning in recent decades, significantly contributing to sea level rise. The main driving factor behind this retreating condition is recent decade atmospheric warming explaining higher melting rates and equilibrium line altitude upward migration. Ice dynamic is also playing an important role especially in glaciers calving into deep fjords or lakes, type of glaciers that are predominant in the Patagonian icefields. In order to better understand their ice dynamics, several recent works have measured ice velocities using feature tracking and other techniques, however, ice thickness is still barely known. In spite of several on the ground radar measurements successfully detecting several hundred of m of ice thickness at the higher plateaus, this variable remains the great missing part of the equation especially when the thickness is approximately deeper than 600 m or where the glacier surfaces are very crevassed or nearby the Equilibrium line Altitude, where on the ground measurements are logistically constrained. In order to tackle the lack of thickness data, a helicopter borne radar system was used to survey several Patagonian temperate glaciers calving into fjords (Glaciares San Rafael and Jorge Montt) or lakes (Nef, Colonia and Steffen). The radar system is comprised by a hanging bow-tie dipole antenna working at a central frequency of 20 MHz. The antenna is an aluminum structure of 7 x 5 x 1.2 m weighting near 350 kg that is hanging at 20 m below a helicopter, and is connected to the helicopter cabin by an optical fiber cable. At the antenna are installed a 3,200 Volts peak transmitter, a two channel radar receiver, and an integrated GPS registering each trace. The helicopter flying speed was kept at near 40 knots and the antenna was normally hanging at 40 m above the ice. The surveys took place along predefined tracks

  11. Robust Control for Lateral and Longitudinal Channels of Small-Scale Unmanned Helicopters

    Directory of Open Access Journals (Sweden)

    Bao Feng


    Full Text Available Lateral and longitudinal channels are two closely related channels whose control stability influences flight performance of small-scale unmanned helicopters directly. This paper presents a robust control approach for lateral and longitudinal channels in the presence of parameter uncertainties and exogenous disturbances. The proposed control approach is performed by two steps. First, by performing system identification in frequency domain, system model of lateral and longitudinal channels can be accurately identified. Then, a robust H∞ state feedback controller is designed to stabilize the helicopter in lateral and longitudinal channels simultaneously under extraneous disturbances situation. The proposed approach takes advantages that it reduces order of the controller by preestimating some parameters (like flapping angles without sacrificing control accuracy. Numerical results show the reliability and effectiveness of the proposed method.

  12. Measurements of atmospheric hydroperoxides over a rural site in central Japan during summers using a helicopter (United States)

    Watanabe, Koichi; Yachi, Chinatsu; Nishibe, Miyuki; Michigami, Serina; Saito, Yukiko; Eda, Nagisa; Yamazaki, Nobuhiro; Hirai, Taiki


    The concentrations of hydroperoxides (H2O2 and MHP), O3, SO2 and NOX* over Imizu City, Toyama Prefecture, Japan were measured during summers using a helicopter. The concentrations of hydroperoxides were analyzed by an HPLC system within 5-10 min after the sampling. The H2O2 concentration was lowest at the surface, and the highest concentration was detected at altitudes of 6000 and 8000 ft. The MHP was also higher in the high-altitude atmosphere. Significantly high concentrations of hydroperoxides were observed when air pollutants were transported from China. The concentration of H2O2 was higher than that of SO2 above 4000 ft where the potential capacity of SO2 oxidation in the aqueous phase is large. A helicopter is useful for measuring of hydroperoxides in the high-altitude atmosphere using an HPLC system in a laboratory.

  13. Comparative analysis on data of ear baric function by hypobaric chamber test between helicopter and fighter pilots%直升机和歼击机飞行员耳气压功能比较

    Institute of Scientific and Technical Information of China (English)

    徐先荣; 汪斌如; 金占国; 张扬


    目的 比较直升机和歼击机飞行员的耳气压功能,为直升机飞行员航卫保障提供参考依据. 方法 询问飞行合格的220名飞行员(直升机飞行员130人,歼击机飞行员90人)的病史,并对飞行员进行电耳镜、纯音测听、声导抗及前鼻镜、鼻内镜检查,无低压舱检查禁忌证者进行耳气压功能检查.①直升机飞行员和歼击机飞行员均坐于低压舱内模拟飞行,以15~20 m/s速率上升至4 000 m,停留5 min,再以5 m/s速率下降返回地面,出舱后再次行电耳镜、纯音测听和声导抗检查,与进舱前的检查结果进行对照.②歼击机飞行员坐于低压舱内,以20~30 m/s速率模拟上升至4 000 m,停留5 min,再以20~25 m/s速率模拟下降返回地面,出舱后再次行电耳镜、纯音测听和声导抗检查,与进舱前的检查结果进行对照.比较两组飞行员耳气压功能不良的发生率. 结果 ①1例直升机飞行员患感冒,电耳镜检查鼓膜Ⅱ度充血,纯音测听轻度传导性聋,声导抗示C型曲线,故未安排进舱而终止检查.②低压舱模拟慢速率(5 m/s)下降时,直升机飞行员耳气压功能不良的发生率(6.20%)高于歼击机飞行员(0.00%),两组差异有统计学意义(x2 =4.16,P<0.05).③低压舱模拟快速率(20~25 m/s)下降时,歼击机飞行员耳气压功能不良的发生率为7.78%(7/90),与慢速率下降高度时直升机飞行员耳气压功能不良的发生率相比,差异无统计学意义(x2=0.21,P>0.05).结论 对不同机种飞行员进行低压舱耳气压功能检查和航空医学训练时,应按不同速率的上升/下降方案进行岗位胜任能力评价.%Objective To compare the ear baric function of helicopter pilots and fighter pilots and to investigate the aeromedical support on helicopter pilots' ear baric function.Methods One hundred and thirty helicopter pilots and 90 fighter pilots were inquired about their health history and examined by electric

  14. 78 FR 7308 - Airworthiness Directives; Bell Helicopter Textron Canada Helicopters (United States)


    ... rivet, or other damage. This proposed AD is prompted by a stress analysis of the tailboom skin that revealed high-stress-concentration areas are susceptible to skin cracking. This condition, if not detected..., environmental, energy, or federalism impacts that might result from adopting the proposals in this document....

  15. Thermal Analysis System (United States)

    DiStefano, III, Frank James (Inventor); Wobick, Craig A. (Inventor); Chapman, Kirt Auldwin (Inventor); McCloud, Peter L. (Inventor)


    A thermal fluid system modeler including a plurality of individual components. A solution vector is configured and ordered as a function of one or more inlet dependencies of the plurality of individual components. A fluid flow simulator simulates thermal energy being communicated with the flowing fluid and between first and second components of the plurality of individual components. The simulation extends from an initial time to a later time step and bounds heat transfer to be substantially between the flowing fluid, walls of tubes formed in each of the individual components of the plurality, and between adjacent tubes. Component parameters of the solution vector are updated with simulation results for each of the plurality of individual components of the simulation.

  16. 3D Vision Based Landing Control of a Small Scale Autonomous Helicopter


    Zhenyu Yu; Kenzo Nonami; Jinok Shin; Demian Celestino


    Autonomous landing is a challenging but important task for Unmanned Aerial Vehicles (UAV) to achieve high level of autonomy. The fundamental requirement for landing is the knowledge of the height above the ground, and a properly designed controller to govern the process. This paper presents our research results in the study of landing an autonomous helicopter. The abovetheground height sensing is based on a 3D vision system. We have designed a simple planefitting method for e...

  17. Helicopter Structures - A Review of Loads, Fatigue Design Techniques and Usage Monitoring (United States)


    component used hero includes overything fromm simple links to large sub-assemblies much s tailbooms. 29. cycle counting ancl the other using the block...Ounsallus AHu64A Rotating Load Usage Monitoring From Fixed Eric Robeson System Informatlon, American Helicopter Society, Proceedings of the National...Applied Aviation Eric Robeson Technology Directorate, Ft Eustis, Virginia, U.S.A., Personal Communications, 1992. 81. Scott Owsley CH.47D Shaft Torque

  18. Particle Swarm Optimization/Greedy-Search Algorithm for Helicopter Mission Assignment in Disaster Relief


    Andreeva-Mori, Adriana; KOBAYASHI, Keiji; Shindo, Masato; アンドレエバ森, アドリアナ; 小林, 啓二; 真道, 雅人


    In the immediate aftermath of a large-scale disaster, optimal helicopter rescue mission assignment is critical to saving many lives. However, the current practice in the field is mostly human centered. The Japan Aerospace Exploration Agency has been developing a decision support system for aircraft operation in order to promptly plan and execute rescue missions. The current research focuses on evacuation missions in particular and investigates the potential of particle swarm optimization with...

  19. Is helicopter evacuation effective in rural trauma transport? (United States)

    Rose, Melanie K; Cummings, G R; Rodning, Charles B; Brevard, Sid B; Gonzalez, Richard P


    Helicopter transport for trauma remains controversial because its appropriate utilization and efficacy with regard to improved survival is unproven. The purpose of this study was to assess rural trauma helicopter transport utilization and effect on patient survival. A retrospective chart review over a 2-year period (2007-2008) was performed of all rural helicopter and ground ambulance trauma patient transports to an urban Level I trauma center. Data was collected with regard to patient mortality and Injury Severity Score (ISS). Miles to the Level I trauma center were calculated from the point where helicopter or ground ambulance transport services initiated contact with the patient to the Level I trauma center. During the 2-year period, 1443 rural trauma patients were transported by ground ambulance and 1028 rural trauma patients were transported by helicopter. Of the patients with ISS of 0 to 10, 471 patients were transported by helicopter and 1039 transported by ground. There were 465 (99%) survivors with ISS 0 to 10 transported by helicopter with an average transport distance of 34.6 miles versus 1034 (99.5%) survivors with ISS 0 to 10 who were transported by ground an average of 41.0 miles. Four hundred and twenty-one patients with ISS 11 to 30 were transported by helicopter an average of 33.3 miles with 367 (87%) survivors versus a 95 per cent survival in 352 patients with ISS 11 to 30 who were transported by ground an average of 39.9 miles. One hundred and thirty-six patients with ISS > 30 were transported by helicopter an average of 32.8 miles with 78 (57%) survivors versus a 69 per cent survival in 52 patients with ISS > 30 who were transported by ground an average of 33.0 miles. Helicopter transport does not seem to improve survival in severely injured (ISS > 30) patients. Helicopter transport does not improve survival and is associated with shorter travel distances in less severely injured (ISS < 10) patients in rural areas. This data questions effective

  20. Modelling optimal location for pre-hospital helicopter emergency medical services. (United States)

    Schuurman, Nadine; Bell, Nathaniel J; L'Heureux, Randy; Hameed, Syed M


    Increasing the range and scope of early activation/auto launch helicopter emergency medical services (HEMS) may alleviate unnecessary injury mortality that disproportionately affects rural populations. To date, attempts to develop a quantitative framework for the optimal location of HEMS facilities have been absent. Our analysis used five years of critical care data from tertiary health care facilities, spatial data on origin of transport and accurate road travel time catchments for tertiary centres. A location optimization model was developed to identify where the expansion of HEMS would cover the greatest population among those currently underserved. The protocol was developed using geographic information systems (GIS) to measure populations, distances and accessibility to services. Our model determined Royal Inland Hospital (RIH) was the optimal site for an expanded HEMS - based on denominator population, distance to services and historical usage patterns. GIS based protocols for location of emergency medical resources can provide supportive evidence for allocation decisions - especially when resources are limited. In this study, we were able to demonstrate conclusively that a logical choice exists for location of additional HEMS. This protocol could be extended to location analysis for other emergency and health services.

  1. Modelling optimal location for pre-hospital helicopter emergency medical services

    Directory of Open Access Journals (Sweden)

    L'Heureux Randy


    Full Text Available Abstract Background Increasing the range and scope of early activation/auto launch helicopter emergency medical services (HEMS may alleviate unnecessary injury mortality that disproportionately affects rural populations. To date, attempts to develop a quantitative framework for the optimal location of HEMS facilities have been absent. Methods Our analysis used five years of critical care data from tertiary health care facilities, spatial data on origin of transport and accurate road travel time catchments for tertiary centres. A location optimization model was developed to identify where the expansion of HEMS would cover the greatest population among those currently underserved. The protocol was developed using geographic information systems (GIS to measure populations, distances and accessibility to services. Results Our model determined Royal Inland Hospital (RIH was the optimal site for an expanded HEMS – based on denominator population, distance to services and historical usage patterns. Conclusion GIS based protocols for location of emergency medical resources can provide supportive evidence for allocation decisions – especially when resources are limited. In this study, we were able to demonstrate conclusively that a logical choice exists for location of additional HEMS. This protocol could be extended to location analysis for other emergency and health services.

  2. Quadrotor helicopter for surface hydrological measurements (United States)

    Pagano, C.; Tauro, F.; Porfiri, M.; Grimaldi, S.


    Surface hydrological measurements are typically performed through user-assisted and intrusive field methodologies which can be inadequate to monitor remote and extended areas. In this poster, we present the design and development of a quadrotor helicopter equipped with digital acquisition system and image calibration units for surface flow measurements. This custom-built aerial vehicle is engineered to be lightweight, low-cost, highly customizable, and stable to guarantee optimal image quality. Quadricopter stability guarantees minimal vibrations during image acquisition and, therefore, improved accuracy in flow velocity estimation through large scale particle image velocimetry algorithms or particle tracking procedures. Stability during the vehicle pitching and rolling is achieved by adopting large arm span and high-wing configurations. Further, the vehicle framework is composed of lightweight aluminum and durable carbon fiber for optimal resilience. The open source Ardupilot microcontroller is used for remote control of the quadricopter. The microcontroller includes an inertial measurement unit (IMU) equipped with accelerometers and gyroscopes for stable flight through feedback control. The vehicle is powered by a 3 cell (11.1V) 3000 mAh Lithium-polymer battery. Electronic equipment and wiring are hosted into the hollow arms and on several carbon fiber platforms in the waterproof fuselage. Four 35A high-torque motors are supported at the far end of each arm with 10 × 4.7 inch propellers. Energy dissipation during landing is accomplished by four pivoting legs that, through the use of shock absorbers, prevent the impact energy from affecting the frame thus causing significant damage. The data capturing system consists of a GoPro Hero3 camera and in-house built camera gimbal and shock absorber damping device. The camera gimbal, hosted below the vehicle fuselage, is engineered to maintain the orthogonality of the camera axis with respect to the water surface by

  3. Flight Operations Noise Tests of Eight Helicopters (United States)



  4. Design and performance prediction of swashplateless helicopter rotors with trailing edge flaps and tabs (United States)

    Falls, Jaye

    This work studies the design of trailing edge controls for swashplateless helicopter primary control, and examines the impact of those controls on the performance of the rotor. The objective is to develop a comprehensive aeroelastic analysis for swashplateless rotors in steady level flight. The two key issues to be solved for this swashplateless control concept are actuation of the trailing edge controls and evaluating the performance of the swashplateless rotor compared to conventionally controlled helicopters. Solving the first requires simultaneous minimization of trailing flap control angles and hinge moments to reduce actuation power. The second issue requires not only the accurate assessment of swashplateless rotor power, but also similar or improved performance compared to conventional rotors. The analysis consists of two major parts, the structural model and the aerodynamic model. The inertial contributions of the trailing edge flap and tab are derived and added to the system equations in the structural model. Two different aerodynamic models are used in the analysis, a quasi-steady thin airfoil theory that includes arbitrary hinge positions for the flap and the tab, and an unsteady lifting line model with airfoil table lookup based on wind tunnel test data and computational fluid dynamics simulation. The design aspect of the problem is investigated through parametric studies of the trailing edge flap and tab for a Kaman-type conceptual rotor and a UH-60A swashplateless variant. The UH-60A model is not changed except for the addition of a trailing edge flap to the rotor blade, and the reduction of pitch link stiffness to imitate a soft root spring. Study of the uncoupled blade response identifies torsional stiffness and flap hinge stiffness as important design features of the swashplateless rotor. Important trailing edge flap and tab design features including index angle, aerodynamic overhang, chord and length are identified through examination of coupled

  5. Static Analysis for Systems Biology

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Rosa, D. Schuch da


    This paper shows how static analysis techniques can help understanding biological systems. Based on a simple example we illustrate the outcome of performing three different analyses extracting information of increasing precision. We conclude by reporting on the potential impact and exploitation o...... of these techniques in systems biology....

  6. An Algebraic Approach for the MIMO Control of Small Scale Helicopter

    CERN Document Server

    Budiyono, A


    The control of small-scale helicopter is a MIMO problem. To use of classical control approach to formally solve a MIMO problem, one needs to come up with multidimensional Root Locus diagram to tune the control parameters. The problem with the required dimension of the RL diagram for MIMO design has forced the design procedure of classical approach to be conducted in cascaded multi-loop SISO system starting from the innermost loop outward. To implement this control approach for a helicopter, a pitch and roll attitude control system is often subordinated to a, respectively, longitudinal and lateral velocity control system in a nested architecture. The requirement for this technique to work is that the inner attitude control loop must have a higher bandwidth than the outer velocity control loop which is not the case for high performance mini helicopter. To address the above problems, an algebraic design approach is proposed in this work. The designed control using s-CDM approach is demonstrated for hovering cont...

  7. Artificial Neural Network Analysis System (United States)


    Contract No. DASG60-00-M-0201 Purchase request no.: Foot in the Door-01 Title Name: Artificial Neural Network Analysis System Company: Atlantic... Artificial Neural Network Analysis System 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Powell, Bruce C 5d. PROJECT NUMBER 5e. TASK NUMBER...34) 27-02-2001 Report Type N/A Dates Covered (from... to) ("DD MON YYYY") 28-10-2000 27-02-2001 Title and Subtitle Artificial Neural Network Analysis

  8. Prediction and measurement of low-frequency harmonic noise of a hovering model helicopter rotor (United States)

    Aggarawal, H. R.; Schmitz, F. H.; Boxwell, D. A.

    Far-field acoustic data for a model helicopter rotor have been gathered in a large open-jet, acoustically treated wind tunnel with the rotor operating in hover and out of ground-effect. The four-bladed Boeing 360 model rotor with advanced airfoils, planform, and tip shape was run over a range of conditions typical of today's modern helicopter main rotor. Near in-plane acoustic measurements were compared with two independent implementations of classical linear theory. Measured steady thrust and torque were used together with a free-wake analysis (to predict the thrust and drag distributions along the rotor radius) as input to this first-principles theoretical approach. Good agreement between theory and experiment was shown for both amplitude and phase for measurements made in those positions that minimized distortion of the radiated acoustic signature at low-frequencies.

  9. Report of the aviation safety review of Department of Energy helicopter operations

    Energy Technology Data Exchange (ETDEWEB)


    In a memorandum dated November 27, 1991, the Secretary of Energy directed the Office of Environment, Safety and Health (EH) to lead, with Program Secretarial Office participation, an aviation safety review of the safe operation of the Department`s helicopter program. The Aviation Safety Review Team comprised of aviation experts from the US Army, the Federal Aviation Administration, private consulting organizations, and Department of Energy (DOE) staff was assembled. The scope of the Aviation Safety Review Team`s appraisals included the following as applicable: policy; operations; maintenance; crew training; previous appraisals; contract requirements; aviation safety analysis reports; refueling facilities and management; night vision goggle (NVG) operations; helicopter limited standdown initiative; Secretary of Energy Notice (SEN) -6D-91 Compliance; and, DOE/contractor organizational structures and responsibilities. The appraisals at each site included a review of aviation policy, manuals, procedures, facilities, and documentation pertaining to management, safety, operations, maintenance, and quality control.

  10. Report of the aviation safety review of Department of Energy helicopter operations

    Energy Technology Data Exchange (ETDEWEB)


    In a memorandum dated November 27, 1991, the Secretary of Energy directed the Office of Environment, Safety and Health (EH) to lead, with Program Secretarial Office participation, an aviation safety review of the safe operation of the Department's helicopter program. The Aviation Safety Review Team comprised of aviation experts from the US Army, the Federal Aviation Administration, private consulting organizations, and Department of Energy (DOE) staff was assembled. The scope of the Aviation Safety Review Team's appraisals included the following as applicable: policy; operations; maintenance; crew training; previous appraisals; contract requirements; aviation safety analysis reports; refueling facilities and management; night vision goggle (NVG) operations; helicopter limited standdown initiative; Secretary of Energy Notice (SEN) -6D-91 Compliance; and, DOE/contractor organizational structures and responsibilities. The appraisals at each site included a review of aviation policy, manuals, procedures, facilities, and documentation pertaining to management, safety, operations, maintenance, and quality control.

  11. Experimental study of flight noise on AS350B2 helicopter

    Institute of Scientific and Technical Information of China (English)

    WANG Huaming; ZHANG Qiang; HU Zhangwei; BAO Jinsong


    A joint flight experiment is conducted by China Aviation Establishment and German Aerospace Center on an Aerospatiale AS350B2 helicopter to investigate rotorcraft flight acoustics at Pingfang airport, Harbing City, China. This paper briefly introduces the methodologies and facilities used in the flight tests. The flight exposure noise levels for ten test flight conditions are showed in the paper and harmonic spectrum and wavelet analysis methods are used for the noise test data processing, which are measured in the flight test in taking off, climbing, forward and descent flight conditions. Results show that the flight noise levels are relatively higher in the climbing and descending flight conditions. The flight noise comes mainly from the tail rotor for the climbing and from the main rotor due to the blade vortex interaction (BVI) for the descending flight conditions. The highest noise level occurs in the forward rotating blade side when the helicopter flys at moderate speed with about 6° descending slide angle.

  12. A simple active controller to suppress helicopter air resonance in hover and forward flight (United States)

    Friedmann, P. P.; Takahashi, M. D.


    A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. This model is used to illustrate the effect of unsteady aerodynamics, forward flight, and torsional flexibility on air resonance. Next, a nominal configuration, which experiences air resonance in forward flight, is selected. A simple multivariable compensator using conventional swashplate inputs and a single body roll rate measurement is then designed. The controller design is based on a linear estimator in conjunction with optimal feedback gains, and the design is done in the frequency domain using the loop-transfer recovery method. The controller is shown to suppress the air resonance instability throughout wide range helicopter loading conditions and forward flight speeds.

  13. The ALICE analysis train system

    CERN Document Server

    Zimmermann, Markus


    In the ALICE experiment hundreds of users are analyzing big datasets on a Grid system. High throughput and short turn-around times are achieved by a centralized system called the LEGO trains. This system combines analysis from different users in so-called analysis trains which are then executed within the same Grid jobs thereby reducing the number of times the data needs to be read from the storage systems. The centralized trains improve the performance, the usability for users and the bookkeeping in comparison to single user analysis. The train system builds upon the already existing ALICE tools, i.e. the analysis framework as well as the Grid submission and monitoring infrastructure. The entry point to the train system is a web interface which is used to configure the analysis and the desired datasets as well as to test and submit the train. Several measures have been implemented to reduce the time a train needs to finish and to increase the CPU efficiency.

  14. 3D Vision Based Landing Control of a Small Scale Autonomous Helicopter

    Directory of Open Access Journals (Sweden)

    Zhenyu Yu


    Full Text Available Autonomous landing is a challenging but important task for Unmanned Aerial Vehicles (UAV to achieve high level of autonomy. The fundamental requirement for landing is the knowledge of the height above the ground, and a properly designed controller to govern the process. This paper presents our research results in the study of landing an autonomous helicopter. The abovetheground height sensing is based on a 3D vision system. We have designed a simple planefitting method for estimating the height over the ground. The method enables vibration free measurement with the camera rigidly attached on the helicopter without using complicated gimbal or active vision mechanism. The estimated height is used by the landing control loop. Considering the ground effect during landing, we have proposed a twostage landing procedure. Two controllers are designed for the two landing stages respectively. The sensing approach and control strategy has been verified in field flight test and has demonstrated satisfactory performance.

  15. Boosting multi-features with prior knowledge for mini unmanned helicopter landmark detection

    Institute of Scientific and Technical Information of China (English)


    Without sufficient real training data, the data driven classification algorithms based on boosting method cannot solely be utilized to applications such as the mini unmanned helicopter landmark image detection. In this paper, we propose an approach which uses a boosting algorithm with the prior knowledge for the mini unmanned helicopter landmark image detection. The stage forward stagewise additive model of boosting is analyzed, and the approach how to combine it with the prior knowledge model is presented. The approach is then applied to landmark image detection, where the multi-features are boosted to solve a series of problems, such as rotation, noises affected, etc. Results of real flight experiments demonstrate that for small training examples the boosted learning system using prior knowledge is dramatically better than the one driven by data only.

  16. Investigation on the use of optimization techniques for helicopter airframe vibrations design studies (United States)

    Sreekanta Murthy, T.


    Results of the investigation of formal nonlinear programming-based numerical optimization techniques of helicopter airframe vibration reduction are summarized. The objective and constraint function and the sensitivity expressions used in the formulation of airframe vibration optimization problems are presented and discussed. Implementation of a new computational procedure based on MSC/NASTRAN and CONMIN in a computer program system called DYNOPT for optimizing airframes subject to strength, frequency, dynamic response, and dynamic stress constraints is described. An optimization methodology is proposed which is thought to provide a new way of applying formal optimization techniques during the various phases of the airframe design process. Numerical results obtained from the application of the DYNOPT optimization code to a helicopter airframe are discussed.

  17. Comparison of broadband noise mechanisms, analyses, and experiments on helicopters, propellers, and wind turbines (United States)

    George, A. R.; Chou, S.-T.


    Experimental data on broadband noise from airfoils are compared, together with analytical methods, in order to identify the mechanisms of noise emission. Rotor noise is categorized into discrete frequency, impulsive, and broadband components, the last having a continuous spectrum originating from a random source. The results of computer simulations of different rotor blade types which produce broadband noise were compared with experimental data and among themselves in terms of predictions of the spectra obtained. Consideration was given to the overall sound pressure level, unsteady turbulence forces, rotational forces, inflow turbulence, self-generated turbulence, and turbulence in the flow. Data are presented for a helicopter rotor and light aircraft propeller. The most significant source was found to be inflow turbulence induced lift fluctuations in helicopter rotors and boundary layer trailing edge noise on large wind energy conversion systems

  18. Helicopter pilot back pain: a preliminary study. (United States)

    Shanahan, D F; Reading, T E


    Because of the high prevalence of back pain experienced by U.S. Army helicopter pilots, a study was conducted to ascertain the feasibility of reproducing these symptoms in the laboratory. A mock-up of a UH-1H seat and control configuration was mounted to a multi-axis vibration simulator (MAVS). Eleven subjects were tested on the apparatus for two 120-min periods. During one period, the MAVS was programmed to reproduce vibrations recorded from a UH-1H in cruise flight. The subjects received no vibration during the other test period. All subjects reported back pain which they described as identical to the pain they experience during flight, during one or more of their test periods. There was no statistical difference between the vibration and nonvibration test conditions (p greater than 0.05) in terms of time of onset of pain or intensity of pain as measured by a visual analog scale. It appears the vibration at the frequencies and amplitudes tested plays little or no role in the etiology of the back symptoms reported by these pilots. It is proposed that the primary etiological factor for these symptoms is the poor posture pilots are obliged to assume for extended periods while operating helicopters.

  19. Nonlinear Feedforward Control for Wind Disturbance Rejection on Autonomous Helicopter

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; A. Danapalasingam, Kumeresan


    for the purpose. The model is inverted for the calculation of rotor collective and cyclic pitch angles given the wind disturbance. The control strategy is then applied on a small helicopter in a controlled wind environment and flight tests demonstrates the effectiveness and advantage of the feedforward controller.......This paper presents the design and verification of a model based nonlinear feedforward controller for wind disturbance rejection on autonomous helicopters. The feedforward control is based on a helicopter model that is derived using a number of carefully chosen simplifications to make it suitable...

  20. Optimal Tracking Controller Design for a Small Scale Helicopter

    Institute of Scientific and Technical Information of China (English)

    Agus Budiyono; Singgih S. Wibowo


    A model helicopter is more difficult to control than its full scale counterpart. This is due to its greater sensitivity to control inputs and disturbances as well as higher bandwidth of dynamics. This work is focused on designing practical tracking controller for a small scale helicopter following predefined trajectories. A tracking controller based on optimal control theory is synthesized as a part of the development of an autonomous helicopter. Some issues with regards to control constraints are addressed.The weighting between state tracking performance and control power expenditure is analyzed. Overall performance of the control design is evaluated based on its time domain histories of trajectories as well as control inputs.

  1. Planning German Army Helicopter Maintenance and Mission Assignment (United States)



  2. Simulating effectiveness of helicopter evasive manoeuvres to RPG attack (United States)

    Anderson, D.; Thomson, D. G.


    The survivability of helicopters under attack by ground troops using rocket propelled grenades has been amply illustrated over the past decade. Given that an RPG is unguided and it is infeasible to cover helicopters in thick armour, existing optical countermeasures are ineffective - the solution is to compute an evasive manoeuvre. In this paper, an RPG/helicopter engagement model is presented. Manoeuvre profiles are defined in the missile approach warning sensor camera image plane using a local maximum acceleration vector. Required control inputs are then computed using inverse simulation techniques. Assessments of platform survivability to several engagement scenarios are presented.

  3. Systematic Process for Building a Fault Diagnoser Based on Petri Nets Applied to a Helicopter

    Directory of Open Access Journals (Sweden)

    Miguel A. Trigos


    Full Text Available This work presents a systematic process for building a Fault Diagnoser (FD, based on Petri Nets (PNs which has been applied to a small helicopter. This novel tool is able to detect both intermittent and permanent faults. The work carried out is discussed from theoretical and practical point of view. The procedure begins with a division of the whole system into subsystems, which are the devices that have to be modeled by using PN, considering both the normal and fault operations. Subsequently, the models are integrated into a global Petri Net diagnoser (PND that is able to monitor a whole helicopter and show critical variables to the operator in order to determine the UAV health, preventing accidents in this manner. A Data Acquisition System (DAQ has been designed for collecting data during the flights and feeding PN diagnoser with them. Several real flights (nominal or under failure have been carried out to perform the diagnoser setup and verify its performance. A summary of the validation results obtained during real flight tests is also included. An extensive use of this tool will improve preventive maintenance protocols for UAVs (especially helicopters and allow establishing recommendations in regulations.

  4. Distribution system modeling and analysis

    CERN Document Server

    Kersting, William H


    For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that allow engineers to simulate, analyze, and optimize distribution systems. Powerful as these programs are, however, without a real understanding of the operating characteristics of a distribution system, engineers using the programs can easily make serious errors in their designs and operating procedures.Distribution System Modeling and Analysis helps prevent those errors. It gives re

  5. Earlier reperfusion in patients with ST-elevation Myocardial infarction by use of helicopter

    Directory of Open Access Journals (Sweden)

    Knudsen Lars


    Full Text Available Abstract Background In patients with ST-elevation myocardial infarction (STEMI reperfusion therapy should be initiated as soon as possible. This study evaluated whether use of a helicopter for transportation of patients is associated with earlier initiation of reperfusion therapy. Material and methods A prospective study was conducted, including patients with STEMI and symptom duration less than 12 hours, who had primary percutaneous coronary intervention (PPCI performed at Aarhus University Hospital in Skejby. Patients with a health care system delay (time from emergency call to first coronary intervention of more than 360 minutes were excluded. The study period ran from 1.1.2011 until 31.12.2011. A Western Denmark Helicopter Emergency Medical Service (HEMS project was initiated 1.6.2011 for transportation of patients with time-critical illnesses, including STEMI. Results The study population comprised 398 patients, of whom 376 were transported by ambulance Emergency Medical Service (EMS and 22 by HEMS. Field-triage directly to the PCI-center was used in 338 of patients. The median system delay was 94 minutes among those field-triaged, and 168 minutes among those initially admitted to a local hospital. Patients transported by EMS and field-triaged were stratified into four groups according to transport distance from the scene of event to the PCI-center: ≤25 km., 26–50 km., 51–75 km. and > 75 km. For these groups, the median system delay was 78, 89, 99, and 141 minutes. Among patients transported by HEMS and field-triaged the estimated median transport distance by ground transportation was 115 km, and the observed system delay was 107 minutes. Based on second order polynomial regression, it was estimated that patients with a transport distance of >60 km to the PCI-center may benefit from helicopter transportation, and that transportation by helicopter is associated with a system delay of less than 120 minutes even at a transport

  6. Load Sharing Multiobjective Optimization Design of a Split Torque Helicopter Transmission

    Directory of Open Access Journals (Sweden)

    Chenxi Fu


    Full Text Available Split torque designs can offer significant advantages over the traditional planetary designs for helicopter transmissions. However, it has two unique properties, gap and phase differences, which result in the risk of unequal load sharing. Various methods have been proposed to eliminate the effect of gap and promote load sharing to a certain extent. In this paper, system design parameters will be optimized to change the phase difference, thereby further improving load sharing. A nonlinear dynamic model is established to measure the load sharing with dynamic mesh forces quantitatively. Afterwards, a multiobjective optimization of a reference split torque design is conducted with the promoting of load sharing property, lightweight, and safety considered as the objectives. The load sharing property, which is measured by load sharing coefficient, is evaluated under multiple operating conditions with dynamic analysis method. To solve the multiobjective model with NSGA-II, an improvement is done to overcome the problem of time consuming. Finally, a satisfied optimal solution is picked up as the final design from the Pareto optimal front, which achieves improvements in all the three objectives compared with the reference design.

  7. 76 FR 66609 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model 407 and 427 Helicopters (United States)


    ...) of this AD. Table A Helicopter model Servo P/N Servo prefix ``HR,'' S/N 407 41011300-101 (BHT 206-076-062- Less than 807. 105). 41011400-101 (BHT 206-076-062- Less than 2248. 107). 427 41011300-101 (BHT 206-076-062- Less than 807. 111). 41011700-101 (BHT 206-076-062- Less than 230. 109). (c) Before...

  8. Requirements analysis and system design

    CERN Document Server

    Maciaszek, Leszek A


    An examination of the methods and techniques used in the analysis and design phases of Information System development. Emphasis is placed upon the application of object technology in enterprise information systems (EIS) with UML being used throughout. Through its excellent balance of practical explanation and theoretical insight the book manages to avoid unnecessary, complicating details without sacrificing rigor. Examples of real-world scenarios are used throughout, giving the reader an understanding of what really goes on within the field of Software Engineering.

  9. Automated Loads Analysis System (ATLAS) (United States)

    Gardner, Stephen; Frere, Scot; O’Reilly, Patrick


    ATLAS is a generalized solution that can be used for launch vehicles. ATLAS is used to produce modal transient analysis and quasi-static analysis results (i.e., accelerations, displacements, and forces) for the payload math models on a specific Shuttle Transport System (STS) flight using the shuttle math model and associated forcing functions. This innovation solves the problem of coupling of payload math models into a shuttle math model. It performs a transient loads analysis simulating liftoff, landing, and all flight events between liftoff and landing. ATLAS utilizes efficient and numerically stable algorithms available in MSC/NASTRAN.

  10. Support of Helicopter 'Free Flight' Operations in the 1996 Olympics (United States)

    Branstetter, James R.; Cooper, Eric G.


    The microcosm of activity surrounding the 1996 Olympic Games provided researchers an opportunity for demonstrating state-of-the art technology in the first large-scale deployment of a prototype digital communication/navigation/surveillance system in a confined environment. At the same time it provided an ideal opportunity for transportation officials to showcase the merits of an integrated transportation system in meeting the operational needs to transport time sensitive goods and provide public safety services under real-world conditions. Five aeronautical CNS functions using a digital datalink system were chosen for operational flight testing onboard 91 aircraft, most of them helicopters, participating in the Atlanta Short-Haul Transportation System. These included: GPS-based Automatic Dependent Surveillance, Cockpit Display of Traffic Information, Controller-Pilot Communications, Graphical Weather Information (uplink), and Automated Electronic Pilot Reporting (downlink). Atlanta provided the first opportunity to demonstrate, in an actual operating environment, key datalink functions which would enhance flight safety and situational awareness for the pilot and supplement conventional air traffic control. The knowledge gained from such a large-scale deployment will help system designers in development of a national infrastructure where aircraft would have the ability to navigate autonomously.

  11. Development of Novel Methods for the Reduction of Noise and Weight in Helicopter Transmissions (United States)

    Dimofte, Florin; Keith, Theo G., Jr.


    Over the 70-year evolution of the helicopter, man's understanding of vibration control has greatly increased. However, in spite of the increased performance, the extent of helicopter vibration problems has not significantly diminished. Crew vibration and noise remains important factors in the design of all current helicopters. With more complex and critical demands being placed on aircrews, it is essential that vibration and noise not impair their performance. A major source of helicopter cabin noise (which has been measured at a sound pressure level of over 100 dB) is the gearbox. Reduction of this noise has been a goal of NASA and the U.S. Army. Gear mesh noise is typically in the frequency range of 1000 to 3000 Hz, a range important for speech. A requirement for U.S. Army/NASA Advanced Rotorcraft Transmission project has been a 10-dB reduction compared to current designs. A combined analytical/experimental effort has been underway, since the end of the 80's, to study effects of design parameters on noise production. The noise generated by the gear mesh can be transmitted to the surrounding media through the bearings that support the gear shaft. Therefore, the use of fluid film bearings instead of rolling element bearings could reduce the transmission noise by 10 dB. In addition, the fluid film bearings that support the gear shaft can change the dynamics of the gear assembly by providing damping to the system and by being softer than rolling element bearings. Wave bearings can attenuate, and filter, the noise generated by a machine component due to the dynamic stiffness and damping coefficients. The attenuation ratio could be as large as 35-40 dB. The noise components at higher frequencies than a synchronous frequency can be almost eliminated.

  12. Flight Test Identification and Simulation of a UH-60A Helicopter and Slung Load (United States)

    Cicolani, Luigi S.; Sahai, Ranjana; Tucker, George E.; McCoy, Allen H.; Tyson, Peter H.; Tischler, Mark B.; Rosen, Aviv


    Helicopter slung-load operations are common in both military and civil contexts. Helicopters and loads are often qualified for these operations by means of flight tests, which can be expensive and time consuming. There is significant potential to reduce such costs both through revisions in flight-test methods and by using validated simulation models. To these ends, flight tests were conducted at Moffett Field to demonstrate the identification of key dynamic parameters during flight tests (aircraft stability margins and handling-qualities parameters, and load pendulum stability), and to accumulate a data base for simulation development and validation. The test aircraft was a UH-60A Black Hawk, and the primary test load was an instrumented 8- by 6- by 6-ft cargo container. Tests were focused on the lateral and longitudinal axes, which are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities; tests were conducted at airspeeds from hover to 80 knots. Using telemetered data, the dynamic parameters were evaluated in near real time after each test airspeed and before clearing the aircraft to the next test point. These computations were completed in under 1 min. A simulation model was implemented by integrating an advanced model of the UH-60A aerodynamics, dynamic equations for the two-body slung-load system, and load static aerodynamics obtained from wind-tunnel measurements. Comparisons with flight data for the helicopter alone and with a slung load showed good overall agreement for all parameters and test points; however, unmodeled secondary dynamic losses around 2 Hz were found in the helicopter model and they resulted in conservative stability margin estimates.

  13. Real-time classification of ground from lidar data for helicopter navigation (United States)

    Eisenkeil, Ferdinand; Schafhitzel, Tobias; Kühne, Uwe; Deussen, Oliver


    Helicopter pilots often have to deal with bad weather conditions and degraded views. Such situations may decrease the pilots' situational awareness significantly. The worst-case scenario would be a complete loss of visual reference during an off-field landing due to brownout or white out. In order to increase the pilots' situational awareness, helicopters nowadays are equipped with different sensors that are used to gather information about the terrain ahead of the helicopter. Synthetic vision systems are used to capture and classify sensor data and to visualize them on multifunctional displays or pilot's head up displays. This requires the input data to be a reliably classified into obstacles and ground. In this paper, we present a regularization-based terrain classifier. Regularization is a popular segmentation method in computer vision and used in active contours. For a real-time application scenario with LIDAR data, we developed an optimization that uses different levels of detail depending on the accuracy of the sensor. After a preprocessing step where points are removed that cannot be ground, the method fits a shape underneath the recorded point cloud. Once this shape is calculated, the points below this shape can be distinguished from elevated objects and are classified as ground. Finally, we demonstrate the quality of our segmentation approach by its application on operational flight recordings. This method builds a part of an entire synthetic vision processing chain, where the classified points are used to support the generation of a real-time synthetic view of the terrain as an assistance tool for the helicopter pilot.

  14. Helicopter noise exposure curves for use in environmental impact assessment (United States)

    Newman, J. S.; Rickley, E. J.; Bland, T. L.


    This report establishes the current (1982) FAA helicopter noise data base for use in environmental impact assessment. The report sets out assumptions, methodologies, and techniques used in arriving at noise-exposure-versus-distance relationships. Noise data are provided for 15 helicopters, including five flight regimes each: takeoff, approach, level flyover, hover in-ground-effect (HIGE) and hover out-of-ground effect (HOGE). When possible, level flyover data are presented for a variety of airspeeds. Sound exposure level (SEL) is provided for all operational modes except hover. In the case of hover operations (both HOGE and HIGE), the maximum A-Weighted Sound Level (LAM) is identified as a function of distance. The report also includes a discussion of helicopter performance characteristics required for full computer modeling of helicopter/heliport noise exposure.

  15. The Use of Commercial Remote Sensing Predicting Helicopter Brownout Conditions (United States)


    landing. 4 Figure 2. Soil caught in rotor downwash, start of brownout (from Brownout California soil resource lab) . A second issue ...Sensing in Predicting Helicopter Brownout Conditions. September 2006 (Top Secret). Tan, Kim H., First Edition, Enviromental Soil Science Marcel

  16. Helicopter transmission arrangements with split-torque gear trains (United States)

    White, G.


    As an alternative to component development, the case for improved drive-train configuration is argued. In particular, the use of torque-splitting gear trains is proposed as a practicable means of improving the effectiveness of helicopter main gearboxes.

  17. 78 FR 40956 - Airworthiness Directives; Eurocopter Deutschland (Eurocopter) Helicopters (United States)


    ... comments to the U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor... helicopters in the air ambulance and offshore operations industries. Since an unsafe condition exists that...

  18. A Computational Tool for Helicopter Rotor Noise Prediction Project (United States)

    National Aeronautics and Space Administration — This SBIR project proposes to develop a computational tool for helicopter rotor noise prediction based on hybrid Cartesian grid/gridless approach. The uniqueness of...

  19. Simulation Study on the Feasibility of Gun-Launched Missile Against Attack Helicopters

    Institute of Scientific and Technical Information of China (English)

    王狂飙; 张天桥


    The feasibility of providing the tank a limited anti-helicopterability with gun-launched missile is studied. A type of simulation model of gun-launched missile against attack helicopters is established. The simulation and the parameter optimization of missile control system under various circumstances are done. The gun-launched missile can directly hit the helicopters in the typical tracks, all the missdistances are less than 1 m and the maximum overload is less than available overload. Gun-launched missile is a feasible choice for tanks against attack helicopters.%研究通过炮射反坦克导弹赋予坦克有限反武装直升机能力的可行性.建立了一种炮射导弹与武装直升机对抗的仿真模型,并在各种情况下进行了系统仿真与导弹控制系统参数优化.经参数优化的炮射导弹在给定的武装直升机各种航迹下,均可直接命中,脱靶量均小于1m,最大过载不超过可用过载.仿真结果表明炮射导弹是坦克对抗武装直升机的一种可行的选择.

  20. Nonlinear coupled rotor-fuselage helicopter vibration studies with higher harmonic control (United States)

    Friedmann, P. P.; Venkatesan, C.; Papavassiliou, I.


    This paper addresses the problem of vibration prediction and vibration reduction in helicopters by means of active control methodologies. The nonlinear equations of a coupled rotor/flexible-fuselage system have been derived using computer algebra, thus relegating this tedious task to the computer. In the solution procedure the trim state and vibratory response of the helicopter are obtained in a single pass by using a harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter in all the rotor and fuselage degrees of freedom. Using this solution procedure, the influence of the fuselage flexibility on the vibratory response is studied. In addition, it is shown that the conventional single frequency HHC is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. A new scheme called MHHC, having multiple higher harmonic pitch inputs, was used to accomplish this task of simultaneously reducing both the vibratory hub loads and fuselage vibratory response. In addition, the uniqueness of this MHHC scheme is explained in detail.


    Institute of Scientific and Technical Information of China (English)

    Yao YU; Yisheng ZHONG


    A 3DOF (three degrees of freedom) helicopter attitude control system with multi-operation points is described as a MIMO time-varying uncertain nonlinear system with unknown constant param-eters, bounded disturbance and nonlinear uncertainty, and a robust output feedback control method based on signal compensation is proposed. A controller designed by this method consists of a nominal controller and a robust compensator. The controller is linear time-invariant and can be realized easily. Robust attitude tracking property of closed-loop system is proven and experimental results show that the designed control system can guarantee high precision robust attitude control under multi-operation points.

  2. Analysis of hybrid solar systems (United States)

    Swisher, J.


    The TRNSYS simulation program was used to evaluate the performance of active charge/passive discharge solar systems with water as the working fluid. TRNSYS simulations are used to evaluate the heating performance and cooling augmentation provided by systems in several climates. The results of the simulations are used to develop a simplified analysis tool similar to the F-chart and Phi-bar procedures used for active systems. This tool, currently in a preliminary stage, should provide the designer with quantitative performance estimates for comparison with other passive, active, and nonsolar heating and cooling designs.

  3. Compositional analysis for linear systems

    NARCIS (Netherlands)

    Kerber, Florian; Schaft, Arjan van der


    Compositional analysis techniques such as assume-guarantee reasoning are frequently used in computer science to validate the design of complex process models. Since many engineering systems are built modularly from interconnections of components, the resulting mathematical models can be arbitrarily

  4. Multicriteria Gain Tuning for Rotorcraft Flight Controls (also entitled The Development of the Conduit Advanced Control System Design and Evaluation Interface with a Case Study Application Fly by Wire Helicopter Design) (United States)

    Biezad, Daniel


    Handling qualities analysis and control law design would seem to be naturally complimenting components of aircraft flight control system design, however these two closely coupled disciplines are often not well integrated in practice. Handling qualities engineers and control system engineers may work in separate groups within an aircraft company. Flight control system engineers and handling quality specialists may come from different backgrounds and schooling and are often not aware of the other group's research. Thus while the handling qualities specifications represent desired aircraft response characteristics, these are rarely incorporated directly in the control system design process. Instead modem control system design techniques are based on servo-loop robustness specifications, and simple representations of the desired control response. Comprehensive handling qualities analysis is often left until the end of the design cycle and performed as a check of the completed design for satisfactory performance. This can lead to costly redesign or less than satisfactory aircraft handling qualities when the flight testing phase is reached. The desire to integrate the fields of handling qualities and flight,control systems led to the development of the CONDUIT system. This tool facilitates control system designs that achieve desired handling quality requirements and servo-loop specifications in a single design process. With CONDUIT, the control system engineer is now able to directly design and control systems to meet the complete handling specifications. CONDUIT allows the designer to retain a preferred control law structure, but then tunes the system parameters to meet the handling quality requirements.

  5. VH-92A Presidential Helicopter (VH-92A) (United States)


    HMX- 1) and support the President worldwide and the Vice President primarily inside the National Capital Region. Mission tasking encompasses two (2...operations) NCR - National Capital Region NM - Nautical Mile OCONUS - Outside the Continental United States SE - Support Equipment VH-92A December 2015...Factor: 19% of Total Aircraft Inventory (TAI) Squadrons: Marine Helicopter Squadron One (HMX-1) Helicopters per (active) squadron: 16 Monthly Flight

  6. Systems analysis - independent analysis and verification

    Energy Technology Data Exchange (ETDEWEB)

    DiPietro, J.P.; Skolnik, E.G.; Badin, J.S. [Energetics, Inc., Columbia, MD (United States)


    The Hydrogen Program of the U.S. Department of Energy (DOE) funds a portfolio of activities ranging from conceptual research to pilot plant testing. The long-term research projects support DOE`s goal of a sustainable, domestically based energy system, and the development activities are focused on hydrogen-based energy systems that can be commercially viable in the near-term. Energetics develops analytic products that enable the Hydrogen Program Manager to assess the potential for near- and long-term R&D activities to satisfy DOE and energy market criteria. This work is based on a pathway analysis methodology. The authors consider an energy component (e.g., hydrogen production from biomass gasification, hybrid hydrogen internal combustion engine (ICE) vehicle) within a complete energy system. The work involves close interaction with the principal investigators to ensure accurate representation of the component technology. Comparisons are made with the current cost and performance of fossil-based and alternative renewable energy systems, and sensitivity analyses are conducted to determine the effect of changes in cost and performance parameters on the projects` viability.

  7. Prognostic Analysis System and Methods of Operation (United States)

    MacKey, Ryan M. E. (Inventor); Sneddon, Robert (Inventor)


    A prognostic analysis system and methods of operating the system are provided. In particular, a prognostic analysis system for the analysis of physical system health applicable to mechanical, electrical, chemical and optical systems and methods of operating the system are described herein.

  8. Analysis of disease spectrum of Army Aviation helicopter pilots in 2006%2006年陆军航空兵直升机飞行员疾病谱分析

    Institute of Scientific and Technical Information of China (English)

    肖丹; 周长明; 于晓春; 孟晨曦; 朱长远; 谢玮华; 苏檩; 任维乐; 李红; 吴新; 叶义财; 闫永平; 门可; 李海涛; 王波; 张磊; 张景霞; 张延亮; 肇刚; 潘建


    Objective To investigate the disease spectrum of Army Aviation helicopter pilots and provide suggestions to aeromedical service. Methods Cases of 516 helicopter pilots, who were in annual physical examination, were randomly sampled and divided into 3 groups by age. Process included reviewing diagnosis history, analyzing spectrum of disease and its distribution by age, as well as the prevalence of common diseases. Rank Sum Ratio was employed for comparing the distribution of common diseases in different age group. Results ① The top 10 diseases in helicopter pilots of the Army Aviation in 2006 were fatty liver (9.88%), hyperlipidemia (6.98%), gallbladder polypus (3.49%), lumbar disc herniation(2.33%), sinus bradycardia (2.33%), gall-stone(2.13%), chronic gastritis (1.74%), kidney cyst (1.55%), calcify of liver (1.36%) and hypertension (1.16%). ② The prevalence of fatty liver in each group was respectively 2.13%, 9. 29% and 45.59%, which was at a relative higher level The prevalence of fatty liver, chronic gastritis, hyperlipidemia, gallbladder polypus, calcify of liver, hypertension and diabetes was significantly different from each age group. ③ The WR of 3 age groups was 0.7486 and it showed a good concordance of common diagnoses in each age group (χ~2=17.97, P<0.05). Conclusions ①The common diseases of helicopter pilot of Army Aviation are prevalent as common as those of Chinese Air Force pilot on the whole. Compared to more frequent prevalence in other military pilots, no nero-related diseases appeared in the top 10 of helicopter pilots. ② The prevalence of fatty liver and hyperlipidemia increases rapidly with age. The accumulative effect of nosogenesis may exist and result in the diseases of lumber, back, neck and shoulder. ③ Rank Sum Ratio is an effective indication for comparing the concordance of common diagnoses in different group.%目的 研究陆军航空兵(陆航)直升机飞行员疾病谱,为航卫保障提供依据.方法 随机抽取2006


    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir Alexandrovich


    Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.

  10. Research and implementation of a shaking seat system for flight simulator (United States)

    Shi, Xiaolin; Yu, Youzhi; Shen, Weiqun; Song, Zishan


    To a helicopter the shaking seat system can simulate the vibration caused by the main rotor, tail rotor, engine, weapon firing, landing, etc. This paper focuses on the research and analysis of the shaking system of a helicopter flight simulator. The vibration model of the seat is built and the system is also developed. According to different flight states of the helicopter the vibration states of the seat are classified based on real measurement data, and the spectra of the vibration are interpolated to model the vibration of the seat. An electro-hydraulic servo system is used to drive the seat to shake along the direction that is parallel to the vertical body axis. The seat is shaken under the instructions at reference height with position close-loop control method, and the control law is PID algorithm. Running parameters of the system are configured by the software. The motional states of the shaking seat are displayed to the user through the visualization software. The main parts of the system and some key technologies of the implementation are also presented in the paper. The system can generate the special vibration environment in the helicopter flight process, and is successfully applied to the flight simulator. So the pilots' immersion feelings are increased.

  11. Quantifying Airborne Induced Polarization effects in helicopter time domain electromagnetics (United States)

    Macnae, James


    This paper derives the Airborne Induced Polarization (AIP) response of an airborne electromagnetic (AEM) system to a horizontal, thin sheet conductor. A vertical component double-dipole approximates helicopter systems with towed concentric horizontal transmitter and receiver loops in frequency- or time-domain. In time domain, the AIP effect typically shows up as late-time negative data with amplitude 4 to 5 orders of magnitude smaller than the early-time peak of the positive AEM responses. Because of limited bandwidth from the short sample time after the decay of inductive responses, accurate extraction of intrinsic AIP parameters other than a minimum chargeability is almost impossible. Modelling further suggests that AIP effects in double-dipole AEM systems can only be reliably detected from polarizable material in the top few tens of metres. A titanium mineral exploration case history from the Lac Brûlé area, Quebec, Canada illustrates strong spatial coherence of AIP minimum chargeability estimates and their independence from other effects such as conductivity and magnetic susceptibility.

  12. Launch vehicle systems design analysis (United States)

    Ryan, Robert; Verderaime, V.


    Current launch vehicle design emphasis is on low life-cycle cost. This paper applies total quality management (TQM) principles to a conventional systems design analysis process to provide low-cost, high-reliability designs. Suggested TQM techniques include Steward's systems information flow matrix method, quality leverage principle, quality through robustness and function deployment, Pareto's principle, Pugh's selection and enhancement criteria, and other design process procedures. TQM quality performance at least-cost can be realized through competent concurrent engineering teams and brilliance of their technical leadership.

  13. A Human Body Analysis System

    Directory of Open Access Journals (Sweden)

    Girondel Vincent


    Full Text Available This paper describes a system for human body analysis (segmentation, tracking, face/hands localisation, posture recognition from a single view that is fast and completely automatic. The system first extracts low-level data and uses part of the data for high-level interpretation. It can detect and track several persons even if they merge or are completely occluded by another person from the camera's point of view. For the high-level interpretation step, static posture recognition is performed using a belief theory-based classifier. The belief theory is considered here as a new approach for performing posture recognition and classification using imprecise and/or conflicting data. Four different static postures are considered: standing, sitting, squatting, and lying. The aim of this paper is to give a global view and an evaluation of the performances of the entire system and to describe in detail each of its processing steps, whereas our previous publications focused on a single part of the system. The efficiency and the limits of the system have been highlighted on a database of more than fifty video sequences where a dozen different individuals appear. This system allows real-time processing and aims at monitoring elderly people in video surveillance applications or at the mixing of real and virtual worlds in ambient intelligence systems.

  14. System for analysis of explosives (United States)

    Haas, Jeffrey S [San Ramon, CA


    A system for analysis of explosives. Samples are spotted on a thin layer chromatography plate. Multi-component explosives standards are spotted on the thin layer chromatography plate. The thin layer chromatography plate is dipped in a solvent mixture and chromatography is allowed to proceed. The thin layer chromatography plate is dipped in reagent 1. The thin layer chromatography plate is heated. The thin layer chromatography plate is dipped in reagent 2.

  15. CIAO: Chandra's data analysis system (United States)

    Fruscione, Antonella; McDowell, Jonathan C.; Allen, Glenn E.; Brickhouse, Nancy S.; Burke, Douglas J.; Davis, John E.; Durham, Nick; Elvis, Martin; Galle, Elizabeth C.; Harris, Daniel E.; Huenemoerder, David P.; Houck, John C.; Ishibashi, Bish; Karovska, Margarita; Nicastro, Fabrizio; Noble, Michael S.; Nowak, Michael A.; Primini, Frank A.; Siemiginowska, Aneta; Smith, Randall K.; Wise, Michael


    The CIAO (Chandra Interactive Analysis of Observations) software package was first released in 1999 following the launch of the Chandra X-ray Observatory and is used by astronomers across the world to analyze Chandra data as well as data from other telescopes. From the earliest design discussions, CIAO was planned as a general-purpose scientific data analysis system optimized for X-ray astronomy, and consists mainly of command line tools (allowing easy pipelining and scripting) with a parameter-based interface layered on a flexible data manipulation I/O library. The same code is used for the standard Chandra archive pipeline, allowing users to recalibrate their data in a consistent way. We will discuss the lessons learned from the first six years of the software's evolution. Our initial approach to documentation evolved to concentrate on recipe-based "threads" which have proved very successful. A multi-dimensional abstract approach to data analysis has allowed new capabilities to be added while retaining existing interfaces. A key requirement for our community was interoperability with other data analysis systems, leading us to adopt standard file formats and an architecture which was as robust as possible to the input of foreign data files, as well as re-using a number of external libraries. We support users who are comfortable with coding themselves via a flexible user scripting paradigm, while the availability of tightly constrained pipeline programs are of benefit to less computationally-advanced users. As with other analysis systems, we have found that infrastructure maintenance and re-engineering is a necessary and significant ongoing effort and needs to be planned in to any long-lived astronomy software.

  16. Living Expert System (LEXSYS). Volume 6 (United States)


    PROTOLEX SUBNET DISCUSSIONS: Attack Helicopter Operations; Low Intensity Conflict; Continuous Operations. Keywords: Dialogue; Discussions; Military commanders; Decision making; Decision aids; LEXSYS (Living Expert System ).

  17. Film analysis systems and applications

    Energy Technology Data Exchange (ETDEWEB)

    Yonekura, Y.; Brill, A.B.


    The different components that can be used in modern film analysis systems are reviewed. TV camera and charge-coupled device sensors coupled to computers provide low cost systems for applications such as those described. The autoradiography (ARG) method provides an important tool for medical research and is especially useful for the development of new radiopharmaceutical compounds. Biodistribution information is needed for estimation of radiation dose, and for interpretation of the significance of observed patterns. The need for such precise information is heightened when one seeks to elucidate physiological principles/factors in normal and experimental models of disease. The poor spatial resolution achieved with current PET-imaging systems limits the information on radioreceptor mapping, neutrotransmitter, and neuroleptic drug distribution that can be achieved from patient studies. The artful use of ARG in carefully-controlled animal studies will be required to provide the additional information needed to fully understand results obtained with this new important research tool. (ERB)

  18. Computational Aeroacoustic Analysis System Development (United States)

    Hadid, A.; Lin, W.; Ascoli, E.; Barson, S.; Sindir, M.


    Many industrial and commercial products operate in a dynamic flow environment and the aerodynamically generated noise has become a very important factor in the design of these products. In light of the importance in characterizing this dynamic environment, Rocketdyne has initiated a multiyear effort to develop an advanced general-purpose Computational Aeroacoustic Analysis System (CAAS) to address these issues. This system will provide a high fidelity predictive capability for aeroacoustic design and analysis. The numerical platform is able to provide high temporal and spatial accuracy that is required for aeroacoustic calculations through the development of a high order spectral element numerical algorithm. The analysis system is integrated with well-established CAE tools, such as a graphical user interface (GUI) through PATRAN, to provide cost-effective access to all of the necessary tools. These include preprocessing (geometry import, grid generation and boundary condition specification), code set up (problem specification, user parameter definition, etc.), and postprocessing. The purpose of the present paper is to assess the feasibility of such a system and to demonstrate the efficiency and accuracy of the numerical algorithm through numerical examples. Computations of vortex shedding noise were carried out in the context of a two-dimensional low Mach number turbulent flow past a square cylinder. The computational aeroacoustic approach that is used in CAAS relies on coupling a base flow solver to the acoustic solver throughout a computational cycle. The unsteady fluid motion, which is responsible for both the generation and propagation of acoustic waves, is calculated using a high order flow solver. The results of the flow field are then passed to the acoustic solver through an interpolator to map the field values into the acoustic grid. The acoustic field, which is governed by the linearized Euler equations, is then calculated using the flow results computed

  19. Automation for System Safety Analysis (United States)

    Malin, Jane T.; Fleming, Land; Throop, David; Thronesbery, Carroll; Flores, Joshua; Bennett, Ted; Wennberg, Paul


    This presentation describes work to integrate a set of tools to support early model-based analysis of failures and hazards due to system-software interactions. The tools perform and assist analysts in the following tasks: 1) extract model parts from text for architecture and safety/hazard models; 2) combine the parts with library information to develop the models for visualization and analysis; 3) perform graph analysis and simulation to identify and evaluate possible paths from hazard sources to vulnerable entities and functions, in nominal and anomalous system-software configurations and scenarios; and 4) identify resulting candidate scenarios for software integration testing. There has been significant technical progress in model extraction from Orion program text sources, architecture model derivation (components and connections) and documentation of extraction sources. Models have been derived from Internal Interface Requirements Documents (IIRDs) and FMEA documents. Linguistic text processing is used to extract model parts and relationships, and the Aerospace Ontology also aids automated model development from the extracted information. Visualizations of these models assist analysts in requirements overview and in checking consistency and completeness.

  20. An experimental investigation of the chopping of helicopter main rotor tip vortices by the tail rotor. Part 2: High speed photographic study (United States)

    Cary, Charles M.


    The interaction of a free vortex and a rotor was recorded photographically using oil smoke and stroboscopic illumination. The incident vortex is normal to the plane of the rotor and crosses the rotor plane. This idealized aerodynamic experiment most nearly corresponds to helicopter flight conditions in which a tip vortex from the main rotor is incident upon the tail rotor while hovering. The high speed photographs reveal important features not observed using conventional photography where the image is the time average of varying instantaneous images. Most prominent is the strong interaction between the rotor tip vortex system and the incident vortex, resulting in the roll-up of the incident vortex around the (stronger) tip vortices and the resulting rapid destabilization of the deformed incident vortex. The viscous interaction is clearly shown also. Other forms of instabilities or wave-like behavior may be apparent from further analysis of the photographs.