WorldWideScience

Sample records for model helicopter carrying

  1. Modeling, Control and Coordination of Helicopter Systems

    CERN Document Server

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

    2012-01-01

    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...

  2. Helicopter fuel burn modeling in AEDT.

    Science.gov (United States)

    2011-08-01

    This report documents work done to enhance helicopter fuel consumption modeling in the Federal Aviation : Administrations Aviation Environmental Design Tool (AEDT). Fuel consumption and flight performance data : were collected from helicopter flig...

  3. 76 FR 10489 - Special Conditions: Bell Helicopter Textron Canada Limited Model 407 Helicopter, Installation of...

    Science.gov (United States)

    2011-02-25

    ... control functions, since this model helicopter has been certificated to meet the applicable requirements... Federal Aviation Administration 14 CFR Part 27 Special Conditions: Bell Helicopter Textron Canada Limited Model 407 Helicopter, Installation of a Hoh Aeronautics, Inc. Autopilot/ Stabilization Augmentation...

  4. 76 FR 2607 - Airworthiness Directives; MD Helicopters, Inc. (MDHI) Model MD900 Helicopters

    Science.gov (United States)

    2011-01-14

    ... MDHI Model MD900 helicopters. That AD currently requires turning on both Vertical Stabilizer Control... Stability Augmentation System (YSAS) for the Model 500N and 600N helicopters and to the VSCS for the Model... also requires turning ON both VSCS switches to reduce pilot workload and to help control the helicopter...

  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

    2012-03-27

    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. Minimum-complexity helicopter simulation math model

    Science.gov (United States)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

    An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.

  7. 76 FR 66609 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model 407 and 427 Helicopters

    Science.gov (United States)

    2011-10-27

    ... Textron Canada (Bell) Model 407 and 427 Helicopters AGENCY: Federal Aviation Administration, DOT. ACTION...., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. You may get the service information identified in this AD from Bell Helicopter Textron Canada Limited, 12,800 Rue...

  8. H II control for model helicopter in hover

    Science.gov (United States)

    Kim, Moo Seok; Kim, Joon Ki; Han, Jeong Yup; Park, Hong Bae; Kang, Soon Ju

    2005-12-01

    This paper presents mathematical model of six degree-of-freedom (6-DOF) helicopter (ERGO50) in hover, and H II feedback controller which is a powerful technique for the MIMO system as a helicopter. Mathematical model of the helicopter is multi-input multi-output (MIMO) and linearized system which accommodates aerodynamics. H II controller based on optimal control theory is used in a myriad application and plays an important role as a valuable precursor to other advanced methods for future work, when we need to improve stability of the helicopter. We design linear-quadratic-gaussian controller as H II controller. Simulation results show good performance.

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

    NARCIS (Netherlands)

    Taamallah, S.

    2015-01-01

    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

  10. 76 FR 20490 - Special Conditions: Eurocopter France Model AS350B Series, AS350D, and EC130 Helicopters...

    Science.gov (United States)

    2011-04-13

    ... operation. These helicopter models are capable of carrying up to six passengers with one pilot, and have a... features include a 3- blade, fully articulated main rotor, an anti-torque tail rotor system, a skid landing...

  11. Modeling, State Estimation and Control of Unmanned Helicopters

    Science.gov (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

  12. 78 FR 37158 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model Helicopters

    Science.gov (United States)

    2013-06-20

    ... Textron Canada (Bell) Model Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... through Friday, except Federal holidays. Examining the AD Docket You may examine the AD docket on the....m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the...

  13. 77 FR 64439 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model Helicopters

    Science.gov (United States)

    2012-10-22

    ... Textron Canada (Bell) Model Helicopters AGENCY: Federal Aviation Administration (FAA) DOT. ACTION: Notice...'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. Examining The AD Docket... Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket...

  14. Helicopter stability and control modeling improvements and verification on two helicopters

    Science.gov (United States)

    Schrage, D. P.; Peters, D. A.; Prasad, J. V. R.; Stumpf, W. F.; He, Chengjian

    1988-01-01

    A linearized model of helicopter flight dynamics is developed which includes the flapping, lead-lag, and dynamic inflow degrees of freedom (DOF). The model is a combination of analytical terms and numerically determined stability derivatives, and is used to investigate the importance of the rotor DOF to stability and control modeling. The results show that the rotor DOF can have a significant impact on some of the natural modes in a linear model. The flap and dynamic inflow DOF show the greatest influence. Flapping exhibits strong coupling to the body, dynamic inflow, and to lead-lag to a lesser extent. Dynamic inflow tends to damp the high-frequency flapping modes, and reduces the damping on coupled body-flap motion. Dynamic inflow also couples to the flapping motion to produce complex roots. With body-flap and lag regressing modes as exceptions, the results show essentially similar behavior for most modes of articulated and hingeless rotor helicopters.

  15. Flap motion of helicopter rotors with novel, dynamic stall model

    Directory of Open Access Journals (Sweden)

    Han Wei

    2016-01-01

    Full Text Available In this paper, a nonlinear flapping equation for large inflow angles and flap angles is established by analyzing the aerodynamics of helicopter blade elements. In order to obtain a generalized flap equation, the Snel stall model was first applied to determine the lift coefficient of the helicopter rotor. A simulation experiment for specific airfoils was then conducted to verify the effectiveness of the Snel stall model as it applies to helicopters. Results show that the model requires no extraneous parameters compared to the traditional stall model and is highly accurate and practically applicable. Based on the model, the relationship between the flapping angle and the angle of attack was analyzed, as well as the advance ratio under the dynamic stall state.

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

    DEFF Research Database (Denmark)

    Bisgaard, Morten

    . This first major contribution of this thesis is the development of a complete helicopter and slung load system model that is shared between the two branches. The generic slung load model can be used to model all body to body slung load suspension types and gives an intuitive and easy-to-use way of modeling...

  17. Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm

    Science.gov (United States)

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

    2017-10-01

    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.

  18. Procedural guide for modelling and analyzing the flight characteristics of a helicopter design using Flightlab

    OpenAIRE

    McVaney, Gary P.

    1993-01-01

    Approved for public release; distribution is unlimited. This thesis presents one method for modelling and analyzing a helicopter design using Flightlab. Flightlab is a computer program that provides for engineering design, analysis and simulation of aircraft using non-linear dynamic modeling techniques. The procedure to model a single main rotor helicopter is outlined using the sample helicopter design in the book 'Helicopter Performance, Stability, and Control' by Ray Prouty. The analysis...

  19. Model predictive control of a 3-DOF helicopter system using ...

    African Journals Online (AJOL)

    ... by simulation, and its performance is compared with that achieved by linear model predictive control (LMPC). Keywords: nonlinear systems, helicopter dynamics, MIMO systems, model predictive control, successive linearization. International Journal of Engineering, Science and Technology, Vol. 2, No. 10, 2010, pp. 9-19 ...

  20. Modeling and control approach to a distinctive quadrotor helicopter.

    Science.gov (United States)

    Wu, Jun; Peng, Hui; Chen, Qing; Peng, Xiaoyan

    2014-01-01

    The referenced quadrotor helicopter in this paper has a unique configuration. It is more complex than commonly used quadrotors because of its inaccurate parameters, unideal symmetrical structure and unknown nonlinear dynamics. A novel method was presented to handle its modeling and control problems in this paper, which adopts a MIMO RBF neural nets-based state-dependent ARX (RBF-ARX) model to represent its nonlinear dynamics, and then a MIMO RBF-ARX model-based global LQR controller is proposed to stabilize the quadrotor's attitude. By comparing with a physical model-based LQR controller and an ARX model-set-based gain scheduling LQR controller, superiority of the MIMO RBF-ARX model-based control approach was confirmed. This successful application verified the validity of the MIMO RBF-ARX modeling method to the quadrotor helicopter with complex nonlinearity. © 2013 Published by ISA. All rights reserved.

  1. Modeling and simulation of coaxial helicopter rotor aerodynamics

    Science.gov (United States)

    Gecgel, Murat

    A framework is developed for the computational fluid dynamics (CFD) analyses of a series of helicopter rotor flowfields in hover and in forward flight. The methodology is based on the unsteady solutions of the three-dimensional, compressible Navier-Stokes equations recast in a rotating frame of reference. The simulations are carried out by solving the developed mathematical model on hybrid meshes that aim to optimally exploit the benefits of both the structured and the unstructured grids around complex configurations. The computer code is prepared for parallel processing with distributed memory utilization in order to significantly reduce the computational time and the memory requirements. The developed model and the simulation methodology are validated for single-rotor-in-hover flowfields by comparing the present results with the published experimental data. The predictive merit of different turbulence models for complex helicopter aerodynamics are tested extensively. All but the kappa-o and LES results demonstrate acceptable agreement with the experimental data. It was deemed best to use the one-equation Spalart-Allmaras turbulence model for the subsequent rotor flowfield computations. First, the flowfield around a single rotor in forward flight is simulated. These time---accurate computations help to analyze an adverse effect of increasing the forward flight speed. A dissymmetry of the lift on the advancing and the retreating blades is observed for six different advance ratios. Since the coaxial rotor is proposed to mitigate the dissymmetry, it is selected as the next logical step of the present investigation. The time---accurate simulations are successfully obtained for the flowfields generated by first a hovering then a forward-flying coaxial rotor. The results for the coaxial rotor in forward flight verify the aerodynamic balance proposed by the previously published advancing blade concept. The final set of analyses aims to investigate if the gap between the

  2. Carry

    DEFF Research Database (Denmark)

    Koijen, Ralph S.J.; Moskowitz, Tobias; Pedersen, Lasse Heje

    2018-01-01

    -sectionally and in time series for a host of different asset classes, including global equities, global bonds, commodities, US Treasuries, credit, and options. Carry is not explained by known predictors of returns from these asset classes, and it captures many of these predictors, providing a unifying framework...... for return predictability. We reject a generalized version of Uncovered Interest Parity and the Expectations Hypothesis in favor of models with varying risk premia, in which carry strategies are commonly exposed to global recession, liquidity, and volatility risks, though none fully explains carry’s premium....

  3. 75 FR 71540 - Airworthiness Directives; Bell Helicopter Textron Canada Model 222, 222B, 222U, 230, and 430...

    Science.gov (United States)

    2010-11-24

    ... Textron Canada Model 222, 222B, 222U, 230, and 430 Helicopters AGENCY: Federal Aviation Administration... known U.S. owners and operators of the specified model Bell Helicopter Textron Canada (Bell) helicopters... Federal holidays. You may get the service information identified in this AD from Bell Helicopter Textron...

  4. Carry

    DEFF Research Database (Denmark)

    Koijen, Ralph S.J.; Moskowitz, Tobias J.; Heje Pedersen, Lasse

    that include global equities, global bonds, currencies, commodities, US Treasuries, credit, and equity index options. This predictability underlies the strong returns to "carry trades" that go long high-carry and short low-carry securities, applied almost exclusively to currencies, but shown here...

  5. Nonlinear State Estimation and Modeling of a Helicopter UAV

    Science.gov (United States)

    Barczyk, Martin

    Experimentally-validated nonlinear flight control of a helicopter UAV has two necessary conditions: an estimate of the vehicle’s states from noisy multirate output measurements, and a nonlinear dynamics model with minimum complexity, physically controllable inputs and experimentally identified parameter values. This thesis addresses both these objectives for the Applied Nonlinear Controls Lab (ANCL)'s helicopter UAV project. A magnetometer-plus-GPS aided Inertial Navigation System (INS) for outdoor flight as well as an Attitude and Heading Reference System (AHRS) for indoor testing are designed, implemented and experimentally validated employing an Extended Kalman Filter (EKF), using a novel calibration technique for the magnetometer aiding sensor added to remove the limitations of an earlier GPS-only aiding design. Next the recently-developed nonlinear observer design methodology of invariant observers is adapted to the aided INS and AHRS examples, employing a rotation matrix representation for the state manifold to obtain designs amenable to global stability analysis, obtaining a direct nonlinear design for gains of the AHRS observer, modifying the previously-proposed Invariant EKF systematic method for computing gains, and culminating in simulation and experimental validation of the observers. Lastly a nonlinear control-oriented model of the helicopter UAV is derived from first principles, using a rigid-body dynamics formulation augmented with models of the on-board subsystems: main rotor forces and blade flapping dynamics, the Bell-Hiller system and flybar flapping dynamics, tail rotor forces, tail gyro unit, engine and rotor speed, servo operation, fuselage drag, and tail stabilizer forces. The parameter values in the resulting models are identified experimentally. Using these the model is further simplified to be tractable for model-based control design.

  6. Autonomous formation flight of helicopters: Model predictive control approach

    Science.gov (United States)

    Chung, Hoam

    Formation flight is the primary movement technique for teams of helicopters. However, the potential for accidents is greatly increased when helicopter teams are required to fly in tight formations and under harsh conditions. This dissertation proposes that the automation of helicopter formations is a realistic solution capable of alleviating risks. Helicopter formation flight operations in battlefield situations are highly dynamic and dangerous, and, therefore, we maintain that both a high-level formation management system and a distributed coordinated control algorithm should be implemented to help ensure safe formations. The starting point for safe autonomous formation flights is to design a distributed control law attenuating external disturbances coming into a formation, so that each vehicle can safely maintain sufficient clearance between it and all other vehicles. While conventional methods are limited to homogeneous formations, our decentralized model predictive control (MPC) approach allows for heterogeneity in a formation. In order to avoid the conservative nature inherent in distributed MPC algorithms, we begin by designing a stable MPC for individual vehicles, and then introducing carefully designed inter-agent coupling terms in a performance index. Thus the proposed algorithm works in a decentralized manner, and can be applied to the problem of helicopter formations comprised of heterogenous vehicles. Individual vehicles in a team may be confronted by various emerging situations that will require the capability for in-flight reconfiguration. We propose the concept of a formation manager to manage separation, join, and synchronization of flight course changes. The formation manager accepts an operator's commands, information from neighboring vehicles, and its own vehicle states. Inside the formation manager, there are multiple modes and complex mode switchings represented as a finite state machine (FSM). Based on the current mode and collected

  7. Model Predictive Control for a Small Scale Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Jianfu Du

    2008-11-01

    Full Text Available Kinematical and dynamical equations of a small scale unmanned helicoper are presented in the paper. Based on these equations a model predictive control (MPC method is proposed for controlling the helicopter. This novel method allows the direct accounting for the existing time delays which are used to model the dynamics of actuators and aerodynamics of the main rotor. Also the limits of the actuators are taken into the considerations during the controller design. The proposed control algorithm was verified in real flight experiments where good perfomance was shown in postion control mode.

  8. MODELING, CONTROL AND NAVIGATION OF AN AUTONOMOUS QUAD-ROTOR HELICOPTER

    Directory of Open Access Journals (Sweden)

    Damir Šoštarić

    2016-06-01

    Full Text Available Autonomous outdoor quad-rotor helicopters increasingly attract the attention of potential researchers. Several structures and configurations have been developed to allow 3D movements. The quadrotor helicopter is made of a rigid cross frame equipped with four rotors. The autonomous quad-rotor architecture has been chosen for this research for its low dimension, good manoeuvrability, simple mechanics and payload capability. This article presents the modelling, control and navigation of an autonomous outdoor quad-rotor helicopter.

  9. 75 FR 41104 - Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta...

    Science.gov (United States)

    2010-07-15

    ... Company (Robinson) Model R22, R22 Alpha, R22 Beta, and R22 Mariner Helicopters, and Model R44, and R44 II... Alpha, R22 Beta, and R22 Mariner helicopters, and Model R44 and R44 II helicopters. The AD would require... Model R22, R22 Alpha, R22 Beta, and R22 Mariner helicopters, serial numbers (S/N) 0002 through 3325...

  10. Quad-Rotor Unmanned Aerial Vehicle Helicopter Modelling & Control

    Directory of Open Access Journals (Sweden)

    Yogianandh Naidoo

    2011-09-01

    Full Text Available This paper presents the investigation of the modelling and control of a quad-rotor helicopter and forms part of research involving the development of an unmanned aerial vehicle (UAV to be used in search and rescue applications. Quad-rotor helicopters consist of two pairs of counter rotating rotors situated at the ends of a cross, symmetric about the centre of gravity, which coincides with the origin of the reference system used. These rotors provide the predominant aerodynamic forces which act on the rotorcraft, and are modelled using momentum theory as well as blade element theory. From this, one can determine the expected payload capacity and lift performance of the rotorcraft. The Euler-Lagrange method has been used to derive the defining equations of motion of the six degree-of-freedom system. The Lagrangian was obtained by modelling the kinetic and potential energy of the system and the external forces obtained from the aerodynamic analysis. Based on this model, a control strategy was developed using linear PD controllers. A numerical simulation was then conducted using MATLAB® Simulink®. First, the derived model was simulated to investigate the behaviour of the rotorcraft, and then a second investigation was conducted to determine the effectiveness of the implemented control system. The results and findings of these investigations are then presented and discussed.

  11. Error propagation in energetic carrying capacity models

    Science.gov (United States)

    Pearse, Aaron T.; Stafford, Joshua D.

    2014-01-01

    Conservation objectives derived from carrying capacity models have been used to inform management of landscapes for wildlife populations. Energetic carrying capacity models are particularly useful in conservation planning for wildlife; these models use estimates of food abundance and energetic requirements of wildlife to target conservation actions. We provide a general method for incorporating a foraging threshold (i.e., density of food at which foraging becomes unprofitable) when estimating food availability with energetic carrying capacity models. We use a hypothetical example to describe how past methods for adjustment of foraging thresholds biased results of energetic carrying capacity models in certain instances. Adjusting foraging thresholds at the patch level of the species of interest provides results consistent with ecological foraging theory. Presentation of two case studies suggest variation in bias which, in certain instances, created large errors in conservation objectives and may have led to inefficient allocation of limited resources. Our results also illustrate how small errors or biases in application of input parameters, when extrapolated to large spatial extents, propagate errors in conservation planning and can have negative implications for target populations.

  12. 76 FR 75772 - Airworthiness Directives; Eurocopter France Model EC 120B Helicopters

    Science.gov (United States)

    2011-12-05

    ... helicopter. DATES: Effective December 20, 2011. ADDRESSES: You may get the service information identified in...'Aviation Civile France (DGAC), which is the aviation authority for France, has issued French AD No. F-2005... the Eurocopter France Model EC 120B helicopters. Related Service Information Eurocopter has issued...

  13. Plan, formulate, discuss and correlate a NASTRAN finite element vibrations model of the Boeing Model 360 helicopter airframe

    Science.gov (United States)

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

    1989-01-01

    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.

  14. Advances in transitional flow modeling applications to helicopter rotors

    CERN Document Server

    Sheng, Chunhua

    2017-01-01

    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.

  15. Dynamics Modeling and Control of a Quad-rotor Helicopter

    Science.gov (United States)

    Hossain, Mohammed Raju

    Unmanned Aerial Vehicles (UAVs) have become a promising field of research due to the enormous potential for both military and civilian applications. This thesis focuses on increasing the autonomy of one type of rotary wing UAV; namely a Quad-rotor Helicopter. In this work a detailed mathematical model was introduced for simulation of the dynamics and control of this system. The dynamic model evolved from a simple set of equations, valid only for hovering, to a complex mathematical model with more realistic aerodynamic factors like thrust factor and drag factor. A simple yet precise tool was developed to measure these aerodynamic factors. An intelligent vision based control technique has been proposed for the critical, near-hovering flight of the vehicle. Finally, a platform was developed and a PD controller was implemented with inertial sensors in order to prepare the platform for implementing the vision-based control in the future.

  16. Real-Time Helicopter Flight Control: Modelling and Control by Linearization and Neural Networks

    OpenAIRE

    Pallett, Tobias J.; Ahmad, Shaheen

    1991-01-01

    In this report we determine the dynamic model of a miniature helicopter in hovering flight. Identification procedures for the nonlinear terms are also described. The model is then used to design several linearized control laws and a neural network controller. The controllers were then flight tested on a miniature helicopter flight control test bed the details of which are also presented in this report. Experimental performance of the linearized and neural network controllers are discussed. It...

  17. Plan, formulate, and discuss a NASTRAN finite element model of the UH-60A helicopter airframe

    Science.gov (United States)

    Dinyovszky, P.; Twomey, W. J.

    1990-01-01

    Under a rotorcraft structural dynamics program sponsored by the NASA Langley Research Center, Sikorsky Aircraft, together with the other major helicopter airframe manufacturers, is engaged in a study to improve the use of finite element analysis to predict the dynamic behavior of helicopter airframes. This program, which was designated DAMVIBS (Design Analysis Methods for VIBrationS), includes activities in the areas of: planning, creating, and documenting finite element models of helicopter airframes; the performance of ground vibration tests; and the correlation of test and analysis. The work performed at Sikorsky Aircraft for planning, creating, and documenting a finite element model of the UH-60A BLACK HAWK helicopter airframe is summarized. A complete description of the components of the helicopter which are to be represented in the model is presented and includes: the structural arrangement, the identification of primary and secondary structure, the components of the drive and power trains, and the attachment of large weight items to the structure. Also presented are the techniques which were used to formulate the structural finite element model for static analysis, for forming the mass and vibration models for dynamic analysis, and the procedures which were used to check out and verify the integrity of the model. Initial predictions for the vibration modes for the helicopter are included.

  18. Adaptive Fuzzy Sliding Mode Control for a Model-Scaled Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Amir Razzaghian

    2016-11-01

    Full Text Available This paper presents a novel Adaptive Fuzzy Sliding Mode Controller (AFSMC for a model-scaled unmanned helicopter as real nonlinear plant. First, in order to efficient control law design, the nonlinear model of the helicopter is reformulated as an affine nonlinear system. To do this aim, a Dynamic Inverter (DI is introduced as a bijective function. The proposed DI is used to interconnect the helicopter actuators' main inputs to the helicopter dynamic inputs. Then, AFSMC is designed to control it, and the asymptotic stability of the closed loop system is proved using Lyapunov stability theorem. To verify the merits of the proposed controller, it is compared with traditional sliding mode control system. Simulation results confirmed that the controller as a robust and stable control method has desired controlling performance and well cope with the undesirable chattering phenomenon.

  19. Construction and Use of a Radio Controlled Model Helicopter for Research.

    Science.gov (United States)

    1985-03-01

    helicopters and is found toddy on some of the cheaper priced model helicopter kits. The other method uses collective pitch control. In this method, the...aBIt± an 9. Six Shooter Instructions, Dave Brown Products , U.S.A. 10. Arm7’ Materiel Ccmmand Pamphlet AACP 706-204, Enqineerinq Desigqn Handbook...Donald I. Layton Code 67-LN 2 Department of Aeronautics Naval Postgraduate School Yonterey, California 93943 6. MAJ Charles J. Hintze 4 8530 Innisfree

  20. The Effects of Ambient Conditions on Helicopter Rotor Source Noise Modeling

    Science.gov (United States)

    Schmitz, Frederic H.; Greenwood, Eric

    2011-01-01

    A new physics-based method called Fundamental Rotorcraft Acoustic Modeling from Experiments (FRAME) is used to demonstrate the change in rotor harmonic noise of a helicopter operating at different ambient conditions. FRAME is based upon a non-dimensional representation of the governing acoustic and performance equations of a single rotor helicopter. Measured external noise is used together with parameter identification techniques to develop a model of helicopter external noise that is a hybrid between theory and experiment. The FRAME method is used to evaluate the main rotor harmonic noise of a Bell 206B3 helicopter operating at different altitudes. The variation with altitude of Blade-Vortex Interaction (BVI) noise, known to be a strong function of the helicopter s advance ratio, is dependent upon which definition of airspeed is flown by the pilot. If normal flight procedures are followed and indicated airspeed (IAS) is held constant, the true airspeed (TAS) of the helicopter increases with altitude. This causes an increase in advance ratio and a decrease in the speed of sound which results in large changes to BVI noise levels. Results also show that thickness noise on this helicopter becomes more intense at high altitudes where advancing tip Mach number increases because the speed of sound is decreasing and advance ratio increasing for the same indicated airspeed. These results suggest that existing measurement-based empirically derived helicopter rotor noise source models may give incorrect noise estimates when they are used at conditions where data were not measured and may need to be corrected for mission land-use planning purposes.

  1. 78 FR 7308 - Airworthiness Directives; Bell Helicopter Textron Canada Helicopters

    Science.gov (United States)

    2013-02-01

    ... Helicopter Textron Canada Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... Helicopter Textron Canada (BHTC) Model 407 helicopters with certain tailboom assemblies installed. This... to the ``Mail'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays...

  2. 77 FR 18970 - Airworthiness Directives; Bell Helicopter Textron Canada Helicopters

    Science.gov (United States)

    2012-03-29

    ... Directives; Bell Helicopter Textron Canada Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... (AD) for the Bell Helicopter Textron Canada Limited (BHTC) Model 407 helicopters. This proposed AD is... through Friday, except Federal holidays. Examining the AD Docket: You may examine the AD docket on the...

  3. 75 FR 71532 - Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta...

    Science.gov (United States)

    2010-11-24

    ... Company (Robinson) Model R22, R22 Alpha, R22 Beta, and R22 Mariner Helicopters, and Model R44, and R44 II... new airworthiness directive (AD) for Robinson Model R22, R22 Alpha, R22 Beta, and R22 Mariner... proposed to require for Robinson Model R22, R22 Alpha, R22 Beta, and R22 Mariner helicopters, serial...

  4. 78 FR 38826 - Airworthiness Directives; Various Helicopter Models

    Science.gov (United States)

    2013-06-28

    ... inspection test, and recording the results on the hoist component history card or equivalent record. The... helicopters have been approved by the aviation authorities of Canada, Italy, France, and Germany and are...; and Recording the results of the load inspection test on the hoist component history card or...

  5. 75 FR 66657 - Airworthiness Directives; Eurocopter Deutschland GmbH Model MBB-BK 117 C-2 Helicopters

    Science.gov (United States)

    2010-10-29

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Model MBB- BK 117 C-2 Helicopters AGENCY: Federal Aviation... (AD) for the Eurocopter Deutschland GmbH (ECD) Model MBB BK 117 C-2 helicopters. This amendment...: 2010-22-07 Eurocopter Deutschland GmbH: Amendment 39-16486; Docket No. FAA-2010-0780; Directorate...

  6. System Identification and 6-DOF Hovering Controller Design of Unmanned Model Helicopter

    Science.gov (United States)

    Kim, Byeongil; Chang, Yushin; Lee, Man Hyung

    For a maneuvering unmanned autonomous helicopter, it is necessary to design a proper controller for each flight mode. In this paper, the overall helicopter dynamics is derived and a hovering model is linearized and transformed into a state-space form. However, since it is difficult to obtain parameters for stability derivatives in the state-space directly, a linear control model is derived by a time-domain parametric system identification method with real flight data of a model helicopter. Then, two different controllers (a linear feedback controller with the proportional gain and a robust controller) are designed and their performances are compared. The simulation results show outstanding performance. The validated controllers can be utilized to enable autonomous flight of a RUAV (Rotorcraft-based Unmanned Aerial Vehicle).

  7. Stability and control modelling. [helicopters in near hovering flight

    Science.gov (United States)

    Curtiss, H. C., Jr.

    1986-01-01

    This paper discusses the influence of rotor dynamics and dynamic inflow on the stability and control characteristics of single rotor helicopters in near hovering flight. Body attitude and rate feedback gain limitations which arise due to rotor dynamics and dynamic inflow are discussed. It is shown that attitude feedback gain is limited primarily by body-flap coupling and rate gain is limited by the lag degrees of freedom. Dynamic inflow is shown to produce significant changes in the modes of motion.

  8. Integrated modeling and robust control for full-envelope flight of robotic helicopters

    Science.gov (United States)

    La Civita, Marco

    Robotic helicopters have attracted a great deal of interest from the university, the industry, and the military world. They are versatile machines and there is a large number of important missions that they could accomplish. Nonetheless, there are only a handful of documented examples of robotic-helicopter applications in real-world scenarios. This situation is mainly due to the poor flight performance that can be achieved and---more important---guaranteed under automatic control. Given the maturity of control theory, and given the large body of knowledge in helicopter dynamics, it seems that the lack of success in flying high-performance controllers for robotic helicopters, especially by academic groups and by small industries, has nothing to do with helicopters or control theory as such. The problem lies instead in the large amount of time and resources needed to synthesize, test, and implement new control systems with the approach normally followed in the aeronautical industry. This thesis attempts to provide a solution by presenting a modeling and control framework that minimizes the time, cost, and both human and physical resources necessary to design high-performance flight controllers. The work is divided in two main parts. The first consists of the development of a modeling technique that allows the designer to obtain a high-fidelity model adequate for both real-time simulation and controller design, with few flight, ground, and wind-tunnel tests and a modest level of complexity in the dynamic equations. The second consists of the exploitation of the predictive capabilities of the model and of the robust stability and performance guarantees of the Hinfinity loop-shaping control theory to reduce the number of iterations of the design/simulated-evaluation/flight-test-evaluation procedure. The effectiveness of this strategy is demonstrated by designing and flight testing a wide-envelope high-performance controller for the Carnegie Mellon University robotic

  9. Helicopter controllability

    OpenAIRE

    Carico, Dean

    1989-01-01

    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...

  10. 76 FR 27958 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model 206A, 206B, and 206B3...

    Science.gov (United States)

    2011-05-13

    ... Textron Canada (Bell) Model 206A, 206B, and 206B3 Helicopters AGENCY: Federal Aviation Administration (FAA...., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. You may get the service information identified in this proposed AD from Bell Helicopter Textron Canada Limited, 12...

  11. 75 FR 56487 - Airworthiness Directives; Erickson Air-Crane Incorporated Model S-64F Helicopters

    Science.gov (United States)

    2010-09-16

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Erickson Air-Crane... Air-Crane Incorporated (Erickson Air-Crane) Model S- 64F helicopters. The AD would require, at... the service information identified in this proposed AD from Erickson Air-Crane Incorporated, 3100...

  12. Integrated optimization analyses of aerodynamic/stealth characteristics of helicopter rotor based on surrogate model

    Directory of Open Access Journals (Sweden)

    Jiang Xiangwen

    2015-06-01

    Full Text Available Based on computational fluid dynamics (CFD method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerodynamic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules: integrated grids generation (the moving-embedded grids for CFD solver and the blade grids for radar cross section (RCS solver are generated by solving Poisson equations and folding approach, aerodynamic/stealth solver (the aerodynamic characteristics are simulated by CFD method based upon Navier–Stokes equations and Spalart–Allmaras (S–A turbulence model, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics (PO, equivalent currents (MEC and quasi-stationary (MQS, and integrated optimization analysis (based upon the surrogate model optimization technique with full factorial design (FFD and radial basis function (RBF, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then time–frequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.

  13. ASSESSING THE ADEQUACY OF MATHEMATICAL MODELS OF THE MI-8MTV HELICOPTER DYNAMICS IN TERMS OF CONTROLLABILITY

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The article considers the adequacy of a mathematical model of Mi-8MTV helicopter dynamics with an exter- nal load in terms of controllability, based on comparison of data obtained from computational experiments and flight testing. The results of evaluation of the Mi-8MTV helicopter mathematical model are presented along with evaluation of the joint mathematical models of helicopter dynamics and dynamics of the external load. Data from flight tests without external load, as well as conclusions made based on flight test results for a helicopter with external load were used as data on the behavior of the real object. The article provides the main results of computational experiments and flight tests. The data is presented in form of the following dependencies: time change of pitch angle and bank angle at a predefined control input; increase of attitude rate of the helicopter; deflection of load in the pitch plane; variations of cable pull force. Based on the analysis of the results of computational experiments a positive conclusion was reached on the adequacy of the mathematical model of dynamics of the Mi-8MTV helicopter with external load in regard to input control reaction. The software based on the model was recognized as a suitable instrument for studying helicopter controllability.

  14. Aeromagnetic survey by a model helicopter at the ruin of ironwork refinement

    Science.gov (United States)

    Funaki, M.; Nishioka, T.

    2007-12-01

     It is difficult to detect the magnetic anomaly resulting from the small scale of magnetic sources as archeological or historical ruins by a helicopter due to the restraint of the low altitude flights in the narrow area. Although a relatively small unmanned helicopters has been commercialized for agriculture use etc., it is too expensive for aeromagnetic surveys. We have developed a small autonomous unmanned helicopter which modified a model helicopter for aeromagnetic survey. A model helicopter (Hirobo Co.; SF40) with a 40cc gasoline engine, length of 143cm from the nose to the tail and dry weight of 15 kg is selected in this study. The irradiated magnetic field from the bottom-center of skid of SF40 was the total magnetic field (R)=3511 nT, inclination (I)=12 degrees and declination (D)=138 degrees. It was reduced to about 1 nT at 3 m downward from the skid during the hovering. When SF40 was covered with a magnetic shield film (Amolic sheet), the distance to measure 1nT diminished to 2 m. As shielding whole body with the film is not effective for reliable and safety flights, the only servomotors having the strong magnetization were shielded by the film. The autonomous flights based on GPS data succeeded. As the control system was too large and heavy for SF40, we are developing more simple and small navigation system for this project. Magnetometer system consists of a 3-axis fluxgate magnetometer, data logger, GPS and battery, recording every second of x, y and z magnetic fields, latitude, longitude, altitude and satellite number during 3 hours. The total weight of the system is 400g. The system was hanged to 2m lower from the skid by a rope (Bird magnetometer) or 2m front form the nose by a carbon fiber pipe (Stinger magnetometer) in order to avoid the magnetic field of SF40. However, the bird magnetometer was not suitable due to the strong noise resulting from the swing of the sensor. An archeological ruin of the ironwork refinement aged 15th century in

  15. Switching model predictive attitude control for a quadrotor helicopter subject to atmospheric disturbances

    OpenAIRE

    Alexis, Kostas; Nikolakopoulos, George; Tzes, Anthony

    2011-01-01

    In this article a Switching Model Predictive Attitude Controller for an Unmanned quadrotor Helicopter subject to atmospheric disturbances is presented. The proposed control scheme is computed based on a Piecewise Affine (PWA) model of the quadrotor’s attitude dynamics, where the effects of the atmospheric turbulence are taken into consideration as additive disturbances. The switchings among the PWA models are ruled by the rate of the rotation angles and for each PWA system a corresponding mod...

  16. Backstepping control for a 3DOF model helicopter with input and output constraints

    Directory of Open Access Journals (Sweden)

    Rong Mei

    2016-02-01

    Full Text Available In this article, a backstepping control scheme is developed for the motion control of a Three degrees of freedom (3DOF model helicopter with unknown external disturbance, modelling uncertainties and input and output constraints. In the developed robust control scheme, augmented state observers are applied to estimate the unknown states, unknown external disturbance and modelling uncertainties. Auxiliary systems are designed to deal with input saturation. A barrier Lyapunov function is employed to handle the output saturation. The stability of closed-loop system is proved by the Lyapunov method. Simulation results show that the designed control scheme is effective at dealing with the motion control of a 3DOF model helicopter in the presence of unknown external disturbance and modelling uncertainties, and input and output saturation.

  17. Small Business Innovations (Helicopters)

    Science.gov (United States)

    1992-01-01

    The amount of engine power required for a helicopter to hover is an important, but difficult, consideration in helicopter design. The EHPIC program model produces converged, freely distorted wake geometries that generate accurate analysis of wake-induced downwash, allowing good predictions of rotor thrust and power requirements. Continuum Dynamics, Inc., the Small Business Innovation Research (SBIR) company that developed EHPIC, also produces RotorCRAFT, a program for analysis of aerodynamic loading of helicopter blades in forward flight. Both helicopter codes have been licensed to commercial manufacturers.

  18. 75 FR 48617 - Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 C-2 Helicopters

    Science.gov (United States)

    2010-08-11

    ... Deutschland GmbH (ECD) Model MBB-BK 117 C-2 Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... 13679, dated March 23, 2007) and adding the following new AD: Eurocopter Deutschland GmbH: Docket No...

  19. Ground shake test of the UH-60A helicopter airframe and comparison with NASTRAN finite element model predictions

    Science.gov (United States)

    Howland, G. R.; Durno, J. A.; Twomey, W. J.

    1990-01-01

    Sikorsky Aircraft, together with the other major helicopter airframe manufacturers, is engaged in a study to improve the use of finite element analysis to predict the dynamic behavior of helicopter airframes, under a rotorcraft structural dynamics program called DAMVIBS (Design Analysis Methods for VIBrationS), sponsored by the NASA-Langley. The test plan and test results are presented for a shake test of the UH-60A BLACK HAWK helicopter. A comparison is also presented of test results with results obtained from analysis using a NASTRAN finite element model.

  20. Direct self-repairing control for a helicopter via quantum multi-model and disturbance observer

    Science.gov (United States)

    Chen, Fuyang; Cai, Ling; Jiang, Bin; Tao, Gang

    2016-02-01

    In this paper, a new direct self-repairing control scheme is developed for a helicopter flight control system with unknown actuator faults and external disturbance. The design of multi-model-based adaptive control is used to accommodate the faulty system under different fault conditions. By appropriate switching based on quantum information technique, the system can be converted to the best model and the corresponding controller. Asymptotic model following performance and system stability is guaranteed. A disturbance observer is introduced to observe the disturbance of the system, which can produce corresponding control signals according to the disturbance. The results including a numerical simulation and a semi-physical verification demonstrate the effectiveness of the proposed self-repairing control approach for the helicopter flight control system.

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

    Directory of Open Access Journals (Sweden)

    Lyu Kehong

    2014-06-01

    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.

  2. Loads and Performance Data from a Wind-Tunnel Test of Generic Model Helicopter Rotor Blades

    Science.gov (United States)

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

    2005-01-01

    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.

  3. Selecting locations for landing of various formations of helicopters using spatial modelling

    International Nuclear Information System (INIS)

    Kovarik, V; Rybansky, M

    2014-01-01

    During crisis situations such as floods, landslides, humanitarian crisis and even military clashes there are situations when it is necessary to send helicopters to the crisis areas. To facilitate the process of searching for the sites suitable for landing, it is possible to use the tools of spatial modelling. The paper describes a procedure of selecting areas potentially suitable for landing of particular formations of helicopters. It lists natural and man-made terrain features that represent the obstacles that can prevent helicopters from landing. It also states specific requirements of the NATO documents that have to be respected when selecting the areas for landing. These requirements relate to a slope of ground and an obstruction angle on approach and exit paths. Creating the knowledge base and graphical models in ERDAS IMAGINE is then described. In the first step of the procedure the areas generally suitable for landing are selected. Then the different configurations of landing points that form the landing sites are created and corresponding outputs are generated. Finally, several tactical requirements are incorporated

  4. [Evolvement of ecological footprint model representing ecological carrying capacity].

    Science.gov (United States)

    Cao, Shu-yan; Xie, Gao-di

    2007-06-01

    Ecological footprint (EF) is an important index of ecological carrying capacity. The original EF model is excellent in simplicity, aggregation, comparability, and lifelikeness in presenting results, but short in predictability, configuration, and applicability. To overcome these shortcomings, many researches were conducted to modify and promote the EF model, and developed it from static with single time scale to diversified ones, which included: 1) time series EF model, 2) input-output analysis based EF model, 3) integrated assessment incorporated EF model, 4) land disturbance degree based EF model, and 5) life cycle analysis based EF model, or component EF model. The function of EF as a measurement of ecological carrying capacity was significantly improved, but its accuracy and integrality still need to be advanced.

  5. Formulation and validation of high-order linearized models of helicopter flight mechanics

    Science.gov (United States)

    Kim, Frederick D.; Celi, Roberto; Tischler, Mark B.

    1990-01-01

    A high-order linearized model of helicopter flight dynamics is extracted from a nonlinear time domain simulation. The model has 29 states that describe the fuselage rigid body degrees of freedom, the flap and lag dynamics in a nonrotating coordinate system, the inflow dynamics, the delayed entry of the horizontal tail into the main rotor wake, and, approximately, the blade torsion dynamics. The nonlinear simulation is obtained by extensively modifying the GENHEL computer program. The results indicate that the agreement between the linearized and the nonlinear model is good for small perturbations, and deteriorates for large amplitude maneuvers.

  6. Wind-Tunnel Survey of an Oscillating Flow Field for Application to Model Helicopter Rotor Testing

    Science.gov (United States)

    Mirick, Paul H.; Hamouda, M-Nabil H.; Yeager, William T., Jr.

    1990-01-01

    A survey was conducted of the flow field produced by the Airstream Oscillator System (AOS) in the Langley Transonic Dynamics Tunnel (TDT). The magnitude of a simulated gust field was measured at 15 locations in the plane of a typical model helicopter rotor when tested in the TDT using the Aeroelastic Rotor Experimental System (ARES) model. These measurements were made over a range of tunnel dynamic pressures typical of those used for an ARES test. The data indicate that the gust field produced by the AOS is non-uniform across the tunnel test section, but should be sufficient to excite a model rotor.

  7. A Reconfiguration Control Scheme for a Quadrotor Helicopter via Combined Multiple Models

    Directory of Open Access Journals (Sweden)

    Fuyang Chen

    2014-08-01

    Full Text Available In this paper, an optimal reconfiguration control scheme is proposed for a quadrotor helicopter with actuator faults via adaptive control and combined multiple models. The combined models set contains several fixed models, an adaptive model and a reinitialized adaptive model. The fixed models and the adaptive model can describe the failure system under different fault conditions. Moreover, the proposed reinitialized adaptive model refers to the closest model of the current system and can improve the speed of convergence effectively. In addition, the reference model is designed in consideration of an optimal control performance index and the principle of the minimum cost to achieve perfect tracking performance. Finally, some simulation results demonstrate the effectiveness of the proposed reconfiguration control scheme for faulty cases.

  8. 77 FR 5425 - Airworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters

    Science.gov (United States)

    2012-02-03

    ... Helicopter Textron Canada Limited Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... the Bell Helicopter Textron Canada Limited (BHTC) Model 427 helicopters. This proposed AD is prompted..., except Federal holidays. Examining the AD Docket: You may examine the AD docket on the Internet at http...

  9. Advanced Airfoils Boost Helicopter Performance

    Science.gov (United States)

    2007-01-01

    Carson Helicopters Inc. licensed the Langley RC4 series of airfoils in 1993 to develop a replacement main rotor blade for their Sikorsky S-61 helicopters. The company's fleet of S-61 helicopters has been rebuilt to include Langley's patented airfoil design, and the helicopters are now able to carry heavier loads and fly faster and farther, and the main rotor blades have twice the previous service life. In aerial firefighting, the performance-boosting airfoils have helped the U.S. Department of Agriculture's Forest Service control the spread of wildfires. In 2003, Carson Helicopters signed a contract with Ducommun AeroStructures Inc., to manufacture the composite blades for Carson Helicopters to sell

  10. Control-Oriented Modeling and System Identification for Nonlinear Trajectory Tracking Control of a Small-Scale Unmanned Helicopter

    Science.gov (United States)

    Pourrezaei Khaligh, Sepehr

    Model-based control design of small-scale helicopters involves considerable challenges due to their nonlinear and underactuated dynamics with strong couplings between the different degrees-of-freedom (DOFs). Most nonlinear model-based multi-input multi-output (MIMO) control approaches require the dynamic model of the system to be affine-in-control and fully actuated. Since the existing formulations for helicopter nonlinear dynamic model do not meet these requirements, these MIMO approaches cannot be applied for control of helicopters and control designs in the literature mostly use the linearized model of the helicopter dynamics around different trim conditions instead of directly using the nonlinear model. The purpose of this thesis is to derive the 6-DOF nonlinear model of the helicopter in an affine-in-control, non-iterative and square input-output formulation to enable many nonlinear control approaches, that require a control-affine and square model such as the sliding mode control (SMC), to be used for control design of small-scale helicopters. A combination of the first-principles approach and system identification is used to derive this model. To complete the nonlinear model of the helicopter required for the control design, the inverse kinematics of the actuating mechanisms of the main and tail rotors are also derived using an approach suitable for the real-time control applications. The parameters of the new control-oriented formulation are identified using a time-domain system identification strategy and the model is validated using flight test data. A robust sliding mode control (SMC) is then designed using the new formulation of the helicopter dynamics and its robustness to parameter uncertainties and wind disturbances is tested in simulations. Next, a hardware-in-the-loop (HIL) testbed is designed to allow for the control implementation and gain tuning as well as testing the robustness of the controller to external disturbances in a controlled

  11. General model and control of an n rotor helicopter

    International Nuclear Information System (INIS)

    Sidea, A G; Brogaard, R Yding; Andersen, N A; Ravn, O

    2014-01-01

    The purpose of this study was to create a dynamic, nonlinear mathematical model of a multirotor that would be valid for different numbers of rotors. Furthermore, a set of Single Input Single Output (SISO) controllers were implemented for attitude control. Both model and controllers were tested experimentally on a quadcopter. Using the combined model and controllers, simple system simulation and control is possible, by replacing the physical values for the individual systems

  12. General model and control of an n rotor helicopter

    Science.gov (United States)

    Sidea, A. G.; Yding Brogaard, R.; Andersen, N. A.; Ravn, O.

    2014-12-01

    The purpose of this study was to create a dynamic, nonlinear mathematical model of a multirotor that would be valid for different numbers of rotors. Furthermore, a set of Single Input Single Output (SISO) controllers were implemented for attitude control. Both model and controllers were tested experimentally on a quadcopter. Using the combined model and controllers, simple system simulation and control is possible, by replacing the physical values for the individual systems.

  13. General model and control of an n rotor helicopter

    DEFF Research Database (Denmark)

    Sidea, Adriana-Gabriela; Brogaard, Rune Yding; Andersen, Nils Axel

    2015-01-01

    The purpose of this study was to create a dynamic, nonlinear mathematical model ofa multirotor that would be valid for different numbers of rotors. Furthermore, a set of SingleInput Single Output (SISO) controllers were implemented for attitude control. Both model andcontrollers were tested...

  14. Modeling of Helicopter Pilot Misperception During Overland Navigation

    Science.gov (United States)

    2012-03-01

    into obstacles in the terrain. The Navy Safety Center has adopted James Reason’s Swiss cheese model for understanding the underlying process that...results in mishaps (Reason, 2000). The Swiss cheese model relates a system to a stack of slices of Swiss cheese . Each slice of cheese is a layer of...participant has more time to stray off course, fatigue, or leg heading or timing was forgotten or not as fresh in the mind compared to earlier in the

  15. Modelling of carry-over in recovery furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Fakhrai, Reza [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Metallurgy

    2000-04-01

    Development of mathematical modelling of the combustion process in the furnace of recovery boilers is the subject of this work. This work as a continuation of many years of modelling efforts carried out at KTH/Vaerme- och Ugnsteknik focussed particularly on: char bed modelling; droplets-wall interaction modelling; and carry-over modelling. The char bed model has been studied. Droplets/parcels were considered as a single reactor working independently of the other droplets. The mass of the droplets was not distributed uniformly but induced in the landing place. The droplets hitting the char bed will stick to it and they are alive and part of the calculation. In this way the distribution of the mass on the char bed is only dependent on the parameters which effect flight history such as droplet/parcel diameter, boilers flow field, etc. The droplet- wall interaction model has been studied and found to be very important for obtaining the correct temperature distribution in the recovery furnace. The new approach is based on removal of droplets which hits the wall in the upper part of the recovery boiler from carryover calculation. This model has been proposed and implemented into the GRFM (General Recovery Furnace Model). The carryover modelling effort was based on mass balance in which the number and physical statistics of the droplets/parcel were estimated and the amount of unburned mass was calculated. All of the above listed models were tested together with all other models of heat and mass transfer processes in recovery furnaces using a GRFM. Three-dimensional numerical simulations of the industrial recovery boiler (63 kg/s, 82 bar, 480 deg C) were performed. The number of grid was 232,000 and the number of air ports in this simulation was 178. The air entering the furnace by these ports has different flow rates. Flow and temperature fields as well as species distributions were calculated. The results show good agreement with previously published data and modelling

  16. Modelling and robust control of an unmanned coaxial rotor helicopter with unstructured uncertainties

    Directory of Open Access Journals (Sweden)

    Zhi-Yan Dong

    2017-01-01

    Full Text Available A complete methodology for an unmanned coaxial rotor helicopter with unstructured uncertainties was proposed to achieve high-accuracy tracking performance from modelling to robust control. An integrative approach was introduced to systematically construct a whole dynamic model. The key parameters were selected carefully after iteratively being checked by empirical coefficients to decrease the budget and risk of programme. Moreover, a new control scheme is proposed to simultaneously incorporate six inputs to control six states based on the investment of singularity value responses and the general rule of relative gain array. Coprime factor uncertainty model is considered to represent a class of unstructured uncertainties, such as unmolded actuator dynamics and unpredicted interferences between two rotors. Furthermore, the H ∞ loop-shaping control was proposed to apply the control design of the coaxial rotor helicopter to manage complicated uncertainties and multivariable coupling. Finally, simulation results show the effectiveness of the proposed controller design in the step response of the closed loop. The stable closed-loop plant is achieved and the tolerant size of unstructured uncertainty is up to 36.09%. Good step responses and satisfied decoupling were also investigated in detail.

  17. High-order state space simulation models of helicopter flight mechanics

    Science.gov (United States)

    Kim, Frederick D.; Celi, Roberto; Tischler, Mark B.

    1993-01-01

    This paper describes the formulation and validation of a high-order linearized mathematical model of helicopter flight mechanics, which includes rotor flap and lag degrees of freedom as well as inflow dynamics. The model is extracted numerically from an existing nonlinear, blade element, real-time simulation model. Extensive modifications in the formulation and solution process of the nonlinear model, required for a theoetically rigorous linearization, are described in detail. The validation results show that the linearized model successfully captures the coupled rotor-fuselage dynamics in the frequency band most critical for the design of advanced flight control systems. Additional results quantify the extent to which the order of the model can be reduced without loss of fidelity.

  18. A state-space free-vortex hybrid wake model for helicopter rotors

    Science.gov (United States)

    Wasileski, Bryan J.

    This paper presents the development of a new hybrid wake model merging two distinctly different modeling approaches into a single, more comprehensive solution. The objective of the work was to leverage the strengths of each individual wake model creating a more flexible and extensible solution that could be used across the entire flight envelope of a helicopter. The results of the work indicate that the two wakes models can be successfully merged. The results also show that hybrid wake provides a mechanism by which finite-state wake imparts a level of stability on the free wake solution allowing the free wake to provide consistent, repeatable results from hover through high speed forward flight. While the new hybrid wake includes the geometric distortion needed for predicting the off-axis control response, the new model, as configured in this work, shows no sign of improvement in this area.

  19. Identification and simulation evaluation of an AH-64 helicopter hover math model

    Science.gov (United States)

    Schroeder, J. A.; Watson, D. C.; Tischler, M. B.; Eshow, M. M.

    1991-01-01

    Frequency-domain parameter-identification techniques were used to develop a hover mathematical model of the AH-64 Apache helicopter from flight data. The unstable AH-64 bare-airframe characteristics without a stability-augmentation system were parameterized in the convectional stability-derivative form. To improve the model's vertical response, a simple transfer-function model approximating the effects of dynamic inflow was developed. Additional subcomponents of the vehicle were also modeled and simulated, such as a basic engine response for hover and the vehicle stick dynamic characteristics. The model, with and without stability augmentation, was then evaluated by AH-64 pilots in a moving-base simulation. It was the opinion of the pilots that the simulation was a satisfactory representation of the aircraft for the tasks of interest. The principal negative comment was that height control was more difficult in the simulation than in the aircraft.

  20. 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

    2010-01-01

    -blade/control-system aeroelastic analysis. The rotor blade analysis was in good agreement and validated by comparing with DYMORE. Numerical results were obtained for a four-bladed, small-scale, articulated rotor rotating in vacuum and in a wind tunnel to simulate forward-flight conditions and its aerodynamic effects. The complete......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...

  1. Validation of a mathematical model for Bell 427 Helicopter using parameter estimation techniques and flight test data

    Science.gov (United States)

    Crisan, Emil Gabriel

    Certification requirements, optimization and minimum project costs, design of flight control laws and the implementation of flight simulators are among the principal applications of system identification in the aeronautical industry. This document examines the practical application of parameter estimation techniques to the problem of estimating helicopter stability and control derivatives from flight test data provided by Bell Helicopter Textron Canada. The purpose of this work is twofold: a time-domain application of the Output Error method using the Gauss-Newton algorithm and a frequency-domain identification method to obtain the aerodynamic and control derivatives of a helicopter. The adopted model for this study is a fully coupled, 6 degree of freedom (DoF) state space model. The technique used for rotorcraft identification in time-domain was the Maximum Likelihood Estimation method, embodied in a modified version of NASA's Maximum Likelihood Estimator program (MMLE3) obtained from the National Research Council (NRC). The frequency-domain system identification procedure is incorporated in a comprehensive package of user-oriented programs referred to as CIFERRTM. The coupled, 6 DoF model does not include the high frequency main rotor modes (flapping, lead-lag, twisting), yet it is capable of modeling rotorcraft dynamics fairly accurately as resulted from the model verification. The identification results demonstrate that MMLE3 is a powerful and effective tool for extracting reliable helicopter models from flight test data. The results obtained in frequency-domain approach demonstrated that CIFERRTM could achieve good results even on limited data.

  2. Modeling helicopter blade dynamics using a modified Myklestad-Prohl transfer matrix method

    OpenAIRE

    Cuesta, Juan D.

    1994-01-01

    Approved for public release, distribution unlimited Rotor blade vibratory stresses are of utmost importance in helicopter design. A modified Myklestad-Prohl method for rotating beams has been coded to assist in preliminary helicopter rotor blade design. The rotor blade dynamics program is part of the Joint Army/Navy Rotorcraft Analysis and Design (JANRAD) program which was developed to aid in the preliminary design and analysis of helicopter rotor performance, stability and control, and ro...

  3. An optimization modeling approach to awarding large fire support wildfire helicopter contracts from the US Forest Service

    Science.gov (United States)

    Stephanie A. Snyder; Keith D. Stockmann; Gaylord E. Morris

    2012-01-01

    The US Forest Service used contracted helicopter services as part of its wildfire suppression strategy. An optimization decision-modeling system was developed to assist in the contract selection process. Three contract award selection criteria were considered: cost per pound of delivered water, total contract cost, and quality ratings of the aircraft and vendors....

  4. 77 FR 60883 - Special Conditions: Eurocopter France (ECF) Model EC225LP Helicopter, Installation of a Search...

    Science.gov (United States)

    2012-10-05

    ... reference in TC No. H4EU or the applicable regulations in effect on the date of application for the change... the ECF model EC225LP helicopter because of a novel or unusual design feature, special conditions are... Architecture, we concurred with AW's recommendations, which is consistent with the requirement of subparagraph...

  5. 75 FR 79312 - Special Conditions: Eurocopter France (ECF) Model EC225LP Helicopter, Installation of a Search...

    Science.gov (United States)

    2010-12-20

    ... reference in TC No. H4EU or the applicable regulations in effect on the date of application for the change... standards for the ECF model EC225LP helicopter because of a novel or unusual design feature, special... (b)(3) and (b)(4) of the SAR Mode System Architecture, the commenter asks if both the sensor...

  6. 78 FR 65163 - Airworthiness Directives; Sikorsky Aircraft Corporation-Manufactured (Sikorsky) Model Helicopters...

    Science.gov (United States)

    2013-10-31

    ...- 042, replace the following parts with airworthy parts that have zero (0) hours TIS: (i) All Air Force... estimated work hours to accomplish: 26 work hours (2 work hours per helicopter) for the fleet to review the helicopter records or to remove a part to determine if an affected part is installed; 845 work hours (65 work...

  7. 77 FR 55166 - Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model Helicopters

    Science.gov (United States)

    2012-09-07

    ... LCF2 count from the engine ``history recorder'' (HR), and calculating the LCF1 and LCF2 fatigue... hours time-in-service for the part as shown in Table 1 of ESB 72-0041, for those helicopters with the GE... these parts are replaced as part of the periodic maintenance on the helicopter; A minimal amount of time...

  8. 77 FR 42421 - Airworthiness Directives; Bell Helicopter Textron Canada Helicopters

    Science.gov (United States)

    2012-07-19

    ... Textron Canada Helicopters AGENCY: Federal Aviation Administration (FAA), Department of Transportation... (AD) superseding an existing airworthiness directive for Bell Helicopter Textron Canada (Bell) Model... through Friday, except Federal holidays. Examining The AD Docket You may examine the AD docket on the...

  9. Vibratory Loads Data from a Wind-Tunnel Test of Structurally Tailored Model Helicopter Rotors

    Science.gov (United States)

    Yeager, William T., Jr.; Hamouda, M-Nabil H.; Idol, Robert F.; Mirick, Paul H.; Singleton, Jeffrey D.; Wilbur, Matthew L.

    1991-01-01

    An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems.

  10. Analysis of a Swashplate Mechanism of the Hingeless Rotor Hub with the Flybar in a Model Helicopter, Part I: Kinematics

    Science.gov (United States)

    Sabaapour, Mohammad Reza; Zohoor, Hassan

    Swashplate mechanism is the steering control mechanism used in most helicopters. It is a complex multi-loop closed kinematic chain which controls the angles of attack of the main rotor blades. In most new model helicopters, this mechanism is also equipped with the bell-hiller stabilizer bar (flybar), to improve the stability. This paper aimed at the kinematic analysis of one of the latest architectures of the swashplate mechanism, used for hingeless rotor with the flybar. Hence, the position analysis of each module and whole mechanism, based on parallel manipulators concept with more details involved than other works, was presented here. The kinematic model was further developed to obtain Jacobian matrices, velocity and acceleration analysis in detail. Finally, a particular example was conducted and compared with an ADAMS rigid body dynamic model, to verify the analytical model. In many simulated cases, the results matched.

  11. Disturbance Observer Based Control of Multirotor Helicopters Based on a Universal Model with Unstructured Uncertainties

    Directory of Open Access Journals (Sweden)

    Ye Xie

    2015-01-01

    Full Text Available To handle different perspectives of unstructured uncertainties, two robust control techniques on the basis of a universal model are studied in this paper. Rather than building a model only applicable to a specific small-scale multirotor helicopter (MHeli, the paper proposes a modeling technique to develop a universal model-framework. Particularly, it is straightforward to apply the universal model to a certain MHeli because the contribution and allocation matrix is proposed in the model-framework. Based on the model uncertainties, the load perturbation of the rotor is the primary focus due to its indispensable importance in the tracking performance. In contrast to the common methods, it is proposed to take this unstructured uncertainty in that external disturbance and designs disturbance observer (DOB. In addition, a class of lead-compensator is specifically designed as for compensating phase lag induced by DOB. Compared with H∞ loop-shaping, greater robust tracking performance on rejecting load perturbation could be achieved as a tradeoff between robust stability and tracking performance which is successfully avoided with DOB-based control strategy.

  12. Analysis of a Swashplate Mechanism of the Hingeless Rotor Hub with the Flybar in a Model Helicopter, Part II: Dynamics

    Science.gov (United States)

    Sabaapour, Mohammad Reza; Zohoor, Hassan

    Swashplate mechanism is the steering control mechanism, used in most helicopters. It is a complex multi-loop closed kinematic chain which controls the angles of attack of the main rotor blades. In most new model helicopters, this mechanism is also equipped with the bell-hiller stabilizer bar (flybar), to improve the stability. The main purpose of this paper is the dynamic analysis of a swashplate mechanism, one of the latest architectures, used for hingeless rotor with the flybar. The underlying kinematics has been discussed in Part I. Thus, the detailed dynamic analysis of the whole mechanism and each part are presented here. The analyses are based on the parallel manipulators concept and the virtual work principle. Also an ADAMS rigid body dynamic model was developed to verify the results of the analytical model. In many simulated cases, the results matched.

  13. Helicopter noise measurements data report. volume II. helicopter models: Bell 212 (UH-1N), Sikorsky S-61 (SH-3A), Sikorsky S-64 'Skycrane' (CH- 54B), Boeing Vertol 'Chinook' (CH-47C)

    Science.gov (United States)

    1977-04-01

    The helicopter models used in this test program were the Hughes 300C, Hughes 500C, Bell 47-G, Bell 206-L, Bell 212 (UH-1N), Sikorsky S-61 (SH-3A), Sikorsky S-64 'Skycrane' (CH-54B), and Boeing Vertol 'Chinook' CH-47C. Volume I contains the measured n...

  14. 75 FR 77524 - Special Conditions: Sikorsky Aircraft Corporation Model S-92A Helicopter; Installation of a...

    Science.gov (United States)

    2010-12-13

    ... helicopter instrument flight (Appendix B) envelope as part of the normal SAR mode sequencing. (3) A pilot... or in the event of a malfunction or failure, assuming corrective action begins within an appropriate...

  15. Helicopter model rotor-blade vortex interaction impulsive noise: Scalability and parametric variations

    Science.gov (United States)

    Splettstoesser, W. R.; Schultz, K. J.; Boxwell, D. A.; Schmitz, F. H.

    1984-01-01

    Acoustic data taken in the anechoic Deutsch-Niederlaendischer Windkanal (DNW) have documented the blade vortex interaction (BVI) impulsive noise radiated from a 1/7-scale model main rotor of the AH-1 series helicopter. Averaged model scale data were compared with averaged full scale, inflight acoustic data under similar nondimensional test conditions. At low advance ratios (mu = 0.164 to 0.194), the data scale remarkable well in level and waveform shape, and also duplicate the directivity pattern of BVI impulsive noise. At moderate advance ratios (mu = 0.224 to 0.270), the scaling deteriorates, suggesting that the model scale rotor is not adequately simulating the full scale BVI noise; presently, no proved explanation of this discrepancy exists. Carefully performed parametric variations over a complete matrix of testing conditions have shown that all of the four governing nondimensional parameters - tip Mach number at hover, advance ratio, local inflow ratio, and thrust coefficient - are highly sensitive to BVI noise radiation.

  16. Flight validated high-order models of UAV helicopter dynamics in hover and forward flight using analytical and parameter identification techniques

    Science.gov (United States)

    Bhandari, Subodh

    There has been a significant growth in the use of UAV helicopters for a multitude of military and civilian applications over the last few years. Due to these numerous applications, from crop dusting to remote sensing, UAV helicopters are now a major topic of interest within the aerospace community. The main research focus is on the development of automatic flight control systems (AFCS). The design of AFCS for these vehicles requires a mathematical model representing the dynamics of the vehicle. The mathematical model is developed either from first-principles, using the equations of motion of the vehicle, or from the flight data, using parameter identification techniques. The traditional six-degrees-of-freedom (6-DoF) dynamics model is not suitable for high-bandwidth control system design. Such models are valid only within the low- to mid-frequency range. The agility and high maneuverability of small-scale helicopters require a high-bandwidth control system for full authority autonomous performance. The design of a high-bandwidth control system in turn requires a high-fidelity simulation model that is able to capture the key dynamics of the helicopter. These dynamics include the rotor dynamics. This dissertation presents the development of a 14-degrees-of-freedom (14-DoF) state-space linear model for the KU Thunder Tiger Raptor 50 UAV helicopter from first-principles and from flight test data using a parameter identification technique for the hovering and forward flight conditions. The model includes rigid body, rotor regressive, rotor inflow, stabilizer bar, and rotor coning dynamics. The model is implemented within The MathWork's MATLAB/Simulink environment. The simulation results show that the high-order model is able to predict the helicopter's dynamics up to the frequency of 30 rad/sec. The main contributions of this dissertation are the development of a high-order simulation model for a small UAV helicopter from first-principles and the identification of a

  17. 78 FR 23688 - Airworthiness Directives; Bell Helicopter Textron Canada Inc. Helicopters

    Science.gov (United States)

    2013-04-22

    ... Textron Canada Inc. Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... Bell Helicopter Textron Canada Inc. (BHT) Model 206A, 206B, and 206L helicopters. This proposed AD..., except Federal holidays. Examining the AD Docket You may examine the AD docket on the Internet at http...

  18. 78 FR 9309 - Airworthiness Directives; MD Helicopters, Inc., Helicopters

    Science.gov (United States)

    2013-02-08

    ... 600N helicopters with a NOTAR fan blade T-T strap part number (P/N) 500N5311-5 and MDHI Model MD900... fan blade tension-torsion strap (T-T strap), part number (P/N) 500N5311-5; and MDHI Model MD900.... (MDHI) Model 500N, 600N and MD900 helicopters to require determining the cure date for each NOTAR fan...

  19. Deterministic learning enhanced neutral network control of unmanned helicopter

    Directory of Open Access Journals (Sweden)

    Yiming Jiang

    2016-11-01

    Full Text Available In this article, a neural network–based tracking controller is developed for an unmanned helicopter system with guaranteed global stability in the presence of uncertain system dynamics. Due to the coupling and modeling uncertainties of the helicopter systems, neutral networks approximation techniques are employed to compensate the unknown dynamics of each subsystem. In order to extend the semiglobal stability achieved by conventional neural control to global stability, a switching mechanism is also integrated into the control design, such that the resulted neural controller is always valid without any concern on either initial conditions or range of state variables. In addition, deterministic learning is applied to the neutral network learning control, such that the adaptive neutral networks are able to store the learned knowledge that could be reused to construct neutral network controller with improved control performance. Simulation studies are carried out on a helicopter model to illustrate the effectiveness of the proposed control design.

  20. Helicopter electromagnetic survey of the Model Land Area, Southeastern Miami-Dade County, Florida

    Science.gov (United States)

    Fitterman, David V.; Deszcz-Pan, Maria; Prinos, Scott T.

    2012-01-01

    This report describes a helicopter electromagnetic survey flown over the Model Land Area in southeastern Miami-Dade County, Florida, to map saltwater intrusion in the Biscayne aquifer. The survey, which is located south and east of Florida City, Florida, covers an area of 115 square kilometers with a flight-line spacing of 400 meters. A five-frequency, horizontal, coplanar bird with frequencies ranging from 400 to 100,000 Hertz was used. The data were interpreted using differential resistivity analysis and inversion to produce cross sections and resistivity depth-slice maps. The depth of investigation is as deep as 100 meters in freshwater-saturated portions of the Biscayne aquifer and the depth diminishes to about 50 meters in areas that are intruded by saltwater. The results compare favorably with ground-based, time-domain electromagnetic soundings and induction logs from observation wells in the area. The base of a high-resistivity, freshwater-saturated zone mapped in the northern 2 kilometers of the survey area corresponds quite well with the base of the surficial aquifer that has been determined by drilling. In general, saltwater in the survey area extends 9 to 12 kilometers inland from the coast; however, there is a long nose of saltwater centered along the Card Sound Road Canal that extends 15 kilometers inland. The cause of this preferential intrusion is likely due to uncontrolled surface flow along the canal and subsequent leakage of saltwater into the aquifer. Saltwater also extends farther inland in the area between U.S. Highway 1 and Card Sound Road than it does to the west of this area. Until 1944, a railroad grade occupied the current location of U.S. Highway 1. Borrow ditches associated with the railroad grade connected to Barnes Sound and allowed saltwater to flow during droughts and storm surges to within a few kilometers of Florida City. Relicts of this saltwater that settled to the bottom of the Biscayne aquifer can be seen in the helicopter

  1. 77 FR 23638 - Airworthiness Directives; Bell Helicopter Textron, Incorporated Helicopters

    Science.gov (United States)

    2012-04-20

    ..., environmental, energy, or federalism impacts that might result from adopting the proposals in this document. The...-121-9. These grips, installed on Model 205B, 210, and 212 helicopters, are currently unlimited in...

  2. The logistic model-generated carrying capacities, maximum ...

    African Journals Online (AJOL)

    This paper deals with the derivation of logistic models for cattle, sheep and goats in a commercial ranching system in Machakos District, Kenya, a savannah ecosystem with average annual rainfall of 589.3 ± 159.3mm and an area of 10 117ha. It involves modelling livestock population dynamics as discrete-time logistic ...

  3. Helicopter Fatigue Design Guide

    Science.gov (United States)

    1983-11-01

    Utility Tactical Troop Carrying Heavy Lift Air Force: Transport Search and Rescue The sheer scale of the costs of designing and developing a modern...torsion, the latter being related to piano wire and stainless steel 18.8. To my knowledge a 25 % improvement can be ob- tained by shot peening on actual...N testing is not in the test itself, but in the sheer number of tests to be conducted. A modern helicopter may have from 75 to 100 fatigue

  4. Multicenter observational prehospital resuscitation on helicopter study.

    Science.gov (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

    2017-07-01

    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

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

    NARCIS (Netherlands)

    Paternoster, Alexandre

    2013-01-01

    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

  6. Advances in processing, modeling and application of high resolution helicopter TEM data

    DEFF Research Database (Denmark)

    Kirkegaard, Casper

    The history of electromagnetic surveying using airborne methods dates back more than 60 years, but the advent of time domain instruments towed by a helicopter is relatively new. Time domain instruments designed for fixed wing aircraft has previously proved a valuable tool in exploration of conduc...

  7. 76 FR 52593 - Airworthiness Directives; Eurocopter Canada Ltd. Model BO 105 LS A-3 Helicopters

    Science.gov (United States)

    2011-08-23

    ....gov , including any personal information you provide. We will also post a report summarizing each... distribution of power and responsibilities among the various levels of government. For the reasons discussed.... Determine the age since initial installation on any helicopter (age) and the number of flights on each...

  8. 75 FR 53857 - Airworthiness Directives; Eurocopter France Model SA330J Helicopters

    Science.gov (United States)

    2010-09-02

    ... gearbox (MGB) oil cooling fan assembly (fan) rotor blade and the upper section of the guide vane bearing... feeler gauge cannot be inserted between the blade and the housing, this AD requires replacing the two fan... helicopters, which requires, within 10 hours TIS, inspecting for a gap between the MGB fan rotor blade and the...

  9. 75 FR 47197 - Airworthiness Directives; Schweizer Aircraft Corporation (Schweizer) Model 269D Helicopters

    Science.gov (United States)

    2010-08-05

    ... pressure. Further investigation revealed that a portion of a fan impeller blade damaged the oil cooler.... This action requires installing a Scroll Housing Blade Containment Shielding Kit on each helicopter. This amendment is prompted by 21 reports of the blades of the oil cooler impeller separating, one of...

  10. Helicopter Aeromechanics

    Science.gov (United States)

    1985-04-01

    In the past, the helicopter industry has been less aggresive in rursuing the poten- tial benefits of large computers than the fixed-wing aircraft...blade dynamics which is the subject of another conference in this lecture series. The same program also predicts blade flapping behavior . The...edge show very similar azimuthal flight at 0.9R and !=900 (NASA flight tests), from behavior . Figure 51 shows that the sensor at 0.91c can be used as a

  11. 77 FR 30230 - Airworthiness Directives; Eurocopter Deutschland Helicopters

    Science.gov (United States)

    2012-05-22

    ... Deutschland Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Deutschland GmbH Model MBB-BK117 C-2 helicopters with certain Generator Control Units (GCU) installed. This... Deutschland GmbH Model MBB-BK117 C-2 helicopters. EASA advises that during an acceptance test procedure of a...

  12. 77 FR 69556 - Airworthiness Directives; Eurocopter Deutschland Helicopters

    Science.gov (United States)

    2012-11-20

    ... Airworthiness Directives; Eurocopter Deutschland Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... Deutschland GmbH (ECD) Model MBB-BK117 C-2 helicopters with certain Generator Control Units (GCU) installed... unsafe condition for the Eurocopter Deutschland GmbH Model MBB-BK117 C-2 helicopters. EASA advises that...

  13. Helicopter blades running elevation measurement using omnidirectional vision

    Directory of Open Access Journals (Sweden)

    Chengtao CAI

    2017-12-01

    Full Text Available Omnidirectional dynamic space parameters of high-speed rotating helicopter blades are precise 3D vector description of the blades. In particular, the elevation difference is directly related to the aerodynamic performance and maneuverability of the helicopter. The state of the art detection techniques based on optics and common vision have several drawbacks, such as high demands on devices but poor extensibility, limited measurement range and fixed measurement position. In this paper, a novel approach of helicopter blades running elevation measurement is proposed based on omnidirectional vision. With the advantages of panoramic visual imaging integration, 360° field of view and rotation in-variance, high-resolution images of all rotating blades positions are obtained at one time. By studying the non-linear calibration and calculation model of omnidirectional vision system, aiming at solving the problem of inaccurate visual space mapping model, the omnidirectional and full-scale measurement of the elevation difference are finalized. Experiments are carried out on our multifunctional simulation blades test system and the practical blades test tower, respectively. The experimental results demonstrate the effectiveness of the proposed method and show that the proposed method can considerably reduce the complexity of measurement. Keywords: Full-scale measurement, Helicopter blades elevation, Non-linear calibration, Omnidirectional vision, Unified sphere model

  14. Computational modeling of ice cracking and break-up from helicopter blades

    KAUST Repository

    Shiping, Zhang

    2012-06-25

    In order to reduce the danger of impact onto components caused by break-up, it is important to analyze the shape of shed ice accumulated during flight. In this paper, we will present a 3D finite element method (FEM) to predict the shed ice shape by using a fluid-solid interaction (FSI) approach to determine the loads, and linear fracture mechanics to track crack propagation. Typical icing scenarios for helicopters are analyzed, and the possibility of ice break-up is investigated.

  15. 76 FR 13059 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (BHTC) Model 206A, 206B, 206L...

    Science.gov (United States)

    2011-03-10

    ...-16587; AD 2010-26-51] RIN 2120-AA64 Airworthiness Directives; Bell Helicopter Textron Canada Limited... Federal holidays. You may get the service information identified in this AD from Bell Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4, telephone (450) 437-2862 or (800) 363...

  16. IMPACT OF AN UNDERSLUNG LOAD ON A HELICOPTER CONTROLLABILITY

    Directory of Open Access Journals (Sweden)

    2016-01-01

    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

  17. Modeling of predictive muscular strength for sustained one-handed carrying task.

    Science.gov (United States)

    Li, Kai Way; Wang, Chien Wen; Yu, Ruifeng

    2015-01-01

    Manual materials handling (MMH) tasks are common. They are considered major contributors of musculoskeletal injuries and are the sources of financial burden for industries in terms of lost work days and worker compensation costs. One-handed carrying is common and could result in arm fatigue. The purpose of this study was to establish predictive models for one-handed carrying strength considering weight handed and handedness conditions. Twenty male subjects were recruited for the study. The subject carried a weight of 6 or 12 kg using either dominant or non-dominant hand lasting a time period of 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, or 4 minutes. The results showed that handedness (p carrying strength. Predictive models of single arm carrying strength were established under handedness and weight conditions. The MADs of these models ranged from 0.39 to 2.19 kgf. The exponential function based predictive models may be adopted to describe the single arm carrying strength with reasonable predictive errors. The trend of the carrying strength after carrying a load for a certain period may be employed to describe muscular fatigue for sustained carrying tasks.

  18. 77 FR 35306 - Airworthiness Directives; Bell Helicopter Textron, Inc. Helicopters

    Science.gov (United States)

    2012-06-13

    ... Textron, Inc. (BHTI) Model 205A, 205A-1, and 205B helicopters with certain starter/generator power cable... replacing associated parts included in the starter/generator cable kit, P/N CT205-07-94-1. After the power... the power cable connections using a multimeter. This proposal is prompted by the determination that...

  19. 78 FR 41886 - Airworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters

    Science.gov (United States)

    2013-07-12

    ... Textron Canada Limited Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... serial-numbered Bell Helicopter Textron Canada Limited (BHTC) Model 206L, 206L-1, 206L-3, and 206L-4....m. and 5 p.m., Monday through Friday, except Federal holidays. Examining the AD Docket You may...

  20. A model to estimate aquaculture carrying capacity in three areas of the Philippines

    Directory of Open Access Journals (Sweden)

    Tarzan Legović

    2008-12-01

    Full Text Available A model was developed to estimate the production carrying capacity of water bodies based on nutrient inputs from aquaculture and other sources, flushing rates, and the risk of algal blooms for three different areas of the Philippines – Bolinao (marine site, Dagupan (brackishwater site and Taal Lake (freshwater site. The results suggest that aquaculture production in the Taal Lake was greater than the sustainable carrying capacity. Aquaculture structures in Bolinao were close to carrying capacity during average tidal exchange but greater than the carrying capacity during low tidal exchange and no winds.Aquaculture production in the Dagupan estuary has not overcome its carrying capacity even during low flow. However, during very low flow and no tidal flushing, carrying capacity has been overcome.

  1. An Empirical Correction Method for Improving off-Axes Response Prediction in Component Type Flight Mechanics Helicopter Models

    Science.gov (United States)

    Mansur, M. Hossein; Tischler, Mark B.

    1997-01-01

    Historically, component-type flight mechanics simulation models of helicopters have been unable to satisfactorily predict the roll response to pitch stick input and the pitch response to roll stick input off-axes responses. In the study presented here, simple first-order low-pass filtering of the elemental lift and drag forces was considered as a means of improving the correlation. The method was applied to a blade-element model of the AH-64 APache, and responses of the modified model were compared with flight data in hover and forward flight. Results indicate that significant improvement in the off-axes responses can be achieved in hover. In forward flight, however, the best correlation in the longitudinal and lateral off-axes responses required different values of the filter time constant for each axis. A compromise value was selected and was shown to result in good overall improvement in the off-axes responses. The paper describes both the method and the model used for its implementation, and presents results obtained at hover and in forward flight.

  2. Plan, execute, and discuss vibration measurements and correlations to evaluate a NASTRAN finite element model of the AH-64 helicopter airframe

    Science.gov (United States)

    Ferg, D.; Foote, L.; Korkosz, G.; Straub, F.; Toossi, M.; Weisenburger, R.

    1990-01-01

    A ground vibration test was performed on the AH-64 (Apache) helicopter to determine the frequency response of the airframe. The structure was excited at both the main and tail rotor hubs, separately, and response measurements were taken at 102 locations throughout the fuselage structure. Frequency responses were compared and correlated with results from a NASTRAN finite element model of AH-64. In addition, natural frequencies and mode shapes were estimated from the frequency response data and were correlated with analytical results.

  3. Quantifying spatially derived carrying capacity occupation: Framework for characterisation modelling and application to terrestrial acidification

    DEFF Research Database (Denmark)

    Bjørn, Anders; Margni, M.; Bulle, C.

    *year. This metric resembles that of the ecological footprint method and may be compared to the availability of land or water. The framework was applied to the terrestrial acidification impact category. The geochemical steady-state model PROFILE was used to quantify carrying capacities as deposition levels......The popularity of the ecological footprint method and the planetary boundaries concept shows an increasing interest among decision makers in comparing environmental impacts to carrying capacities of natural systems. Recently carrying capacity-based normalisation references were developed for impact...

  4. Estimating the carrying capacity of green mussel cultivation by using net nutrient removal model.

    Science.gov (United States)

    Srisunont, Chayarat; Babel, Sandhya

    2016-11-15

    This study aims to evaluate the nutrient removal potential and carrying capacity of green mussel cultivation by using the mass balance model. The developed model takes into consideration the green mussel growth rate, density and chlorophyll a concentration. The data employed in this study were based on culture conditions at Sriracha Fisheries Research Station, Thailand. Results show that net nutrient removal by green mussel is 3302, 380, and 124mg/year/indv for carbon, nitrogen, and phosphorus respectively. The carrying capacity of green mussel cultivation was found to be 300indv/m 2 based on chlorophyll a concentration which will not release phosphorus in the water environment beyond the standard (45μg-PO 4 -3 -P/L). Higher chlorophyll a concentration results in lowered green mussel carrying capacity. This model can assist farm operators with possible management strategies for a sustainable mussel cultivation and protection of the marine environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. LQR Based PID Controller Design for 3-DOF Helicopter System

    OpenAIRE

    Santosh Kr. Choudhary

    2014-01-01

    In this article, LQR based PID controller design for 3DOF helicopter system is investigated. The 3-DOF helicopter system is a benchmark laboratory model having strongly nonlinear characteristics and unstable dynamics which make the control of such system a challenging task. This article first presents the mathematical model of the 3DOF helicopter system and then illustrates the basic idea and technical formulation for controller design. The paper explains the simple appro...

  6. Robust Adaptive Integral Backstepping Control of a 3-DOF Helicopter

    OpenAIRE

    Zheng Fang; Weinan Gao; Lei Zhang

    2012-01-01

    Unmanned aerial vehicles have enormous potential applications in military and civil fields. A Quanser’s 3‐DOF helicopter is a simplified and benchmark experimental model for validating the effectiveness of various flight control algorithms. The attitude control of the 3‐DOF helicopter is a challenging task since the helicopter is an under‐actuated system with strong coupling and model uncertainty characteristics. In this paper, an adaptive integral backstepping algorithm is proposed to realiz...

  7. The study of aerosol and ozone measurements in lower boundary layer with UAV helicopter platform

    Science.gov (United States)

    Lin, Po-hsiung; Chen, Wen-nai

    2013-04-01

    This study describes the aerosol and ozone measurement in the lower atmospheric boundary layer of highly polluted region at Kao-hsiung, Taiwan with a small unmanned aerial vehicle (UAV) helicopter platform. This UAV helicopter, modified from Gaui-X7 electronic-power model helicopter with autopilot AHRS (Altitude-Head-Reference System) kit, has fast climb speed up to 700 m height and keeps stable status for atmospheric measurements in five-minute fly leg. Several quick-replaced battery packages are ready on ground for field intensive observation. The payload rack under this UAV helicopter carries a micro-Aethalometer (black carbon concentration), ozone meter, temperature-humidity sensor, barometer and a time-lapse digital camera. The field measurement site closes to Linyuan Petrochemical Industrial Park, where is one of the heavy polluted regions in Taiwan. Balloon-borne Vaisala RS-92 radiosonde and CL31 Lidar Ceilometer are used to provide the background of the atmosphere at the same time. More data analysis measured by UAV helicopter and its potential application will be discussed.

  8. Forewarning Model of Regional Water Resources Carrying Capacity Based on Combination Weights and Entropy Principles

    Directory of Open Access Journals (Sweden)

    Rongxing Zhou

    2017-10-01

    Full Text Available As a new development form for evaluating the regional water resources carrying capacity, forewarning regional water resources of their carrying capacities is an important adjustment and control measure for regional water security management. Up to now, most research on this issue have been qualitative analyses, with a lack of quantitative research. For this reason, an index system for forewarning regional water resources of their carrying capacities and grade standards, has been established in Anhui Province, China, in this paper. Subjective weights of forewarning indices can be calculated using a fuzzy analytic hierarchy process, based on an accelerating genetic algorithm, while objective weights of forewarning indices can be calculated by using a projection pursuit method, based on an accelerating genetic algorithm. These two kinds of weights can be combined into combination weights of forewarning indices, by using the minimum relative information entropy principle. Furthermore, a forewarning model of regional water resources carrying capacity, based on entropy combination weight, is put forward. The model can fully integrate subjective and objective information in the process of forewarning. The results show that the calculation results of the model are reasonable and the method has high adaptability. Therefore, this model is worth studying and popularizing.

  9. MODELLING CARRYING CAPACITY FOR THE THANDA PRIVATE GAME RESERVE, SOUTH AFRICA USING LANDSAT 8 MULTISPECTRAL DATA

    Directory of Open Access Journals (Sweden)

    Z. Oumar

    2017-11-01

    Full Text Available Rangelands which consist of grasslands, shrublands and savannahs are used by wildlife for habitat and are the main source of forage for livestock. The assessment and monitoring of rangeland condition is one of the most important factors for rangeland scientists in order to calculate the carrying capacity of livestock with consideration for coexisting wildlife. This study assessed the potential of Landsat 8 multispectral bands and broadband vegetation indices to model woody vegetation parameters such as tree equivalents (TE and total leaf mass (LMASS for the Thanda Private Game Reserve using partial least squares regression (PLSR. The PLSR model predicted TE with an R2 value of 0.76 and a root mean square error (RMSE of 1411 TE/ha using an independent test dataset. LMASS was predicted with an R2 value of 0.67 and a RMSE of 853 kg/ha on an independent test dataset. The predictive models were then inverted to map TE and LMASS over the study area. The modelled TE and LMASS layers were integrated with conventional grazing and browse capacity models to map carrying capacity for the Game Reserve. The study indicates the potential of Landsat 8 multispectral data in carrying capacity modelling. The result is significant for rangeland monitoring in Southern Africa using remote sensing technologies.

  10. Simulation of Flow around Isolated Helicopter Fuselage

    Directory of Open Access Journals (Sweden)

    Garipov A.O.

    2013-04-01

    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.

  11. Simulation of Flow around Isolated Helicopter Fuselage

    Science.gov (United States)

    Kusyumov, A. N.; Mikhailov, S. A.; Romanova, E. V.; Garipov, A. O.; Nikolaev, E. I.; Barakos, G.

    2013-04-01

    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. 77 FR 49705 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-08-17

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Deutschland GmbH Model MBB-BK 117 C-2 helicopters. A page reference of the rotorcraft flight manual in the...

  13. Train Headway Models and Carrying Capacity of Super-Speed Maglev System

    Science.gov (United States)

    He, Shiwei; Song, Rui; Eastham, Tony

    Train headway models are established by analyzing the operation of the Transrapid Super-speed Maglev System (TSMS). The variation in the minimum allowable headway for trains of different speeds and consists is studied under various operational constraints. A potential Beijing-Shanghai Maglev line is used as an illustration to undertake capacity analyses with the model and methods. The example shows that the headway models for analyzing the carrying capacity of Maglev systems are very useful for the configurational design of this new transport system.

  14. 77 FR 72913 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-12-07

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Eurocopter Deutschland GmbH (ECD) Model EC135 helicopters, except the EC 135 P2+ and T2+. This AD requires... apply to all Eurocopter Deutschland GmbH (ECD) model EC135 helicopters, except the EC 135 P2+ and T2...

  15. Hierarchical population model with a carrying capacity distribution for bacterial biofilms

    Science.gov (United States)

    Indekeu, J. O.; Sznajd-Weron, K.

    2003-12-01

    In order to describe biological colonies with a conspicuous hierarchical structure, a time- and space-discrete model for the growth of a rapidly saturating local biological population N(x,t) is derived from a hierarchical random deposition process previously studied in statistical physics. Two biologically relevant parameters, the probabilities of birth, B, and of death, D, determine the carrying capacity K. Due to the randomness the population depends strongly on position x and there is a distribution of carrying capacities, Π(K). This distribution has self-similar character owing to the exponential slowing down of the growth, assumed in this hierarchical model. The most probable carrying capacity and its probability are studied as a function of B and D. The effective growth rate decreases with time, roughly as in a Verhulst process. The model is possibly applicable, for example, to bacteria forming a “towering pillar” biofilm, a structure poorly described by standard Eden or diffusion-limited-aggregation models. The bacteria divide on randomly distributed nutrient-rich regions and are exposed to a random local bactericidal agent (antibiotic spray). A gradual overall temperature or chemical change away from optimal growth conditions reduces bacterial reproduction, while biofilm development degrades antimicrobial susceptibility, causing stagnation into a stationary state.

  16. Noise-Induced Transitions in a Population Growth Model Based on Size-Dependent Carrying Capacity

    Directory of Open Access Journals (Sweden)

    Neeme Lumi

    2014-01-01

    Full Text Available The stochastic dynamics of a population growth model with size-dependent carrying capacity is considered. The effect of a fluctuating environment on population growth is modeled as a multiplicative dichotomous noise. At intermediate values of population size the deterministic counterpart of the model behaves similarly to the Von Foerster model for human population, but at small and very large values of population size substantial differences occur. In the stochastic case, an exact analytical solution for the stationary probability distribution is found. It is established that variation of noise correlation time can cause noise-induced transitions between three different states of the system characterized by qualitatively different behaviors of the probability distributions of the population size. Also, it is shown that, in some regions of the system parameters, variation of the amplitude of environmental fluctuations can induce single unidirectional abrupt transitions of the mean population size.

  17. System dynamics model of Suzhou water resources carrying capacity and its application

    Directory of Open Access Journals (Sweden)

    Li Cheng

    2010-06-01

    Full Text Available A model of Suzhou water resources carrying capacity (WRCC was set up using the method of system dynamics (SD. In the model, three different water resources utilization programs were adopted: (1 continuity of existing water utilization, (2 water conservation/saving, and (3 water exploitation. The dynamic variation of the Suzhou WRCC was simulated with the supply-decided principle for the time period of 2001 to 2030, and the results were characterized based on socio-economic factors. The corresponding Suzhou WRCC values for several target years were calculated by the model. Based on these results, proper ways to improve the Suzhou WRCC are proposed. The model also produced an optimized plan, which can provide a scientific basis for the sustainable utilization of Suzhou water resources and for the coordinated development of the society, economy, and water resources.

  18. Plan, formulate, and discuss a NASTRAN finite element model of the AH-64A helicopter airframe

    Science.gov (United States)

    Christ, Richard A.; Ferg, Douglas A.; Kilroy, Kevin A.; Toossi, Mostafa; Weisenburger, Richard K.

    1990-01-01

    A discussion of modeling plan objectives, followed by a description of the AH-64A aircraft including all general features, major components, and primary and structure definitions are presented. Following the aircraft description, a discussion of the modeling guidelines and model checkout procedure are provided. The NASTRAN finite element analysis is set up to be suitable to predict both static internal loads and vibrations. Finally, the results, schedule, and planned versus actual manhours for this work are presented.

  19. 78 FR 42409 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-07-16

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA...) for Eurocopter Deutschland GmbH (Eurocopter) Model MBB-BK 117 C-2 helicopters. This AD requires... directive (AD): 2013-12-05 Eurocopter Deutschland GmbH Helicopters: Amendment 39- 17483; Docket No. FAA-2013...

  20. 78 FR 31394 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-05-24

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... airworthiness directive (AD) for Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 C-2 helicopters. This AD... directive (AD): 2013-10-05 Eurocopter Deutschland GmbH Helicopters: Amendment 39- 17458; Docket No. FAA-2013...

  1. Modeling induced polarization effects in helicopter time domain electromagnetic data: Synthetic case studies

    DEFF Research Database (Denmark)

    Viezzoli, Andrea; Kaminskiy, Vladislav; Fiandaca, Gianluca

    2017-01-01

    We have developed a synthetic multiparametric modeling and inversion exercise undertaken to study the robustness of inverting airborne time-domain electromagnetic (TDEM) data to extract Cole-Cole parameters. The following issues were addressed: nonuniqueness, ill posedness, dependency on manual...... constrained multiparametric inversion was evaluated, including recovery of chargeability distributions from shallow and deep targets based on analysis of induced polarization (IP) effects, simulated in airborne TDEM data. Different scenarios were studied, including chargeable targets associated...... by a shallower chargeable target, became possible only when full Cole-Cole modeling was used in the inversion. Lateral constraints improved the recoverability of model parameters. Finally, modeling IP effects increased the accuracy of recovered electrical resistivity models....

  2. Vision Aided State Estimation for Helicopter Slung Load System

    DEFF Research Database (Denmark)

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

    2007-01-01

    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...

  3. 78 FR 857 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-01-07

    ...-17302; AD 2012-26-07] RIN 2120-AA64 Airworthiness Directives; Eurocopter France Helicopters AGENCY... airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS350BA helicopters with certain AERAZUR... information, the economic evaluation, any comments received, and other information. The street address for the...

  4. 78 FR 7641 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-02-04

    ...; AD 2013-01-05] RIN 2120-AA64 Airworthiness Directives; Eurocopter France Helicopters AGENCY: Federal... directive (AD) for Eurocopter France (Eurocopter) Model AS350B3 and EC130B4 helicopters. This AD requires... this AD, any incorporated-by-reference service information, the economic evaluation, any comments...

  5. 77 FR 7005 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

    Science.gov (United States)

    2012-02-10

    ... Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters AGENCY: Federal Aviation Administration (FAA... directive (AD) for Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 C-1 and C-2 helicopters. This proposed... Airworthiness Directive (AD): Eurocopter Deutschland GMBH: Docket No. FAA-2012-0101; Directorate Identifier 2010...

  6. 77 FR 32884 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

    Science.gov (United States)

    2012-06-04

    ... Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters AGENCY: Federal Aviation Administration (FAA...) for Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 C-1 and C-2 helicopters. This AD requires... Sec. 39.13 by adding the following new airworthiness directive (AD): 2012-09-11 EUROCOPTER DEUTSCHLAND...

  7. Which melanoma patient carries a BRAF-mutation? A comparison of predictive models.

    Science.gov (United States)

    Eigentler, Thomas; Assi, Zeinab; Hassel, Jessica C; Heinzerling, Lucie; Starz, Hans; Berneburg, Mark; Bauer, Jürgen; Garbe, Claus

    2016-06-14

    In patients with advanced melanoma the detection of BRAF mutations is considered mandatory before the initiation of an expensive treatment with BRAF/MEK inhibitors. Sometimes it is difficult to perform such an analysis if archival tumor tissue is not available and fresh tissue has to be collected. 514 of 1170 patients (44%) carried a BRAF mutation. All models revealed age and histological subtype of melanoma as the two major predictive variables. Accuracy ranged from 0.65-0.71, being best in the random forest model. Sensitivity ranged 0.76-0.84, again best in the random forest model. Specificity was low in all models ranging 0.51-0.55. We collected the clinical data and mutational status of 1170 patients with advanced melanoma and established three different predictive models (binary logistic regression, classification and regression trees, and random forest) to forecast the BRAF status. Up to date statistical models are not able to predict BRAF mutations in an acceptable accuracy. The analysis of the mutational status by sequencing or immunohistochemistry must still be considered as standard of care.

  8. Math modeling for helicopter simulation of low speed, low altitude and steeply descending flight

    Science.gov (United States)

    Sheridan, P. F.; Robinson, C.; Shaw, J.; White, F.

    1982-01-01

    A math model was formulated to represent some of the aerodynamic effects of low speed, low altitude, and steeply descending flight. The formulation is intended to be consistent with the single rotor real time simulation model at NASA Ames Research Center. The effect of low speed, low altitude flight on main rotor downwash was obtained by assuming a uniform plus first harmonic inflow model and then by using wind tunnel data in the form of hub loads to solve for the inflow coefficients. The result was a set of tables for steady and first harmonic inflow coefficients as functions of ground proximity, angle of attack, and airspeed. The aerodynamics associated with steep descending flight in the vortex ring state were modeled by replacing the steady induced downwash derived from momentum theory with an experimentally derived value and by including a thrust fluctuations effect due to vortex shedding. Tables of the induced downwash and the magnitude of the thrust fluctuations were created as functions of angle of attack and airspeed.

  9. A Model-based Health Monitoring and Diagnostic System for the UH-60 Helicopter. Appendix D

    Science.gov (United States)

    Patterson-Hine, Ann; Hindson, William; Sanderfer, Dwight; Deb, Somnath; Domagala, Chuck

    2001-01-01

    Model-based reasoning techniques hold much promise in providing comprehensive monitoring and diagnostics capabilities for complex systems. We are exploring the use of one of these techniques, which utilizes multi-signal modeling and the TEAMS-RT real-time diagnostic engine, on the UH-60 Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) flight research aircraft. We focus on the engine and transmission systems, and acquire sensor data across the 1553 bus as well as by direct analog-to-digital conversion from sensors to the QHuMS (Qualtech health and usage monitoring system) computer. The QHuMS computer uses commercially available components and is rack-mounted in the RASCAL facility. A multi-signal model of the transmission and engine subsystems enables studies of system testability and analysis of the degree of fault isolation available with various instrumentation suites. The model and examples of these analyses will be described and the data architectures enumerated. Flight tests of this system will validate the data architecture and provide real-time flight profiles to be further analyzed in the laboratory.

  10. [Simulation and prediction of water environmental carrying capacity in Liaoning Province based on system dynamics model].

    Science.gov (United States)

    Wang, Jian; Li, Xue-liang; Li, Fa-yun; Bao, Hong-xu

    2009-09-01

    By the methods of system dynamics, a water environmental carrying capacity (WECC) model was constructed, and the dynamic trend of the WECC in Liaoning Province was simulated by using this model, in combining with analytical hierarchy process (AHP) and the vector norm method. It was predicted that under the conditions of maintaining present development schemes, the WECC in this province in 2000-2050 would be decreased year after year. Only increasing water resources supply while not implementing scientific and rational management of water environment could not improve the regional WECC, and the integration of searching for new and saving present water resources with controlling wastewater pollution and reducing sewage discharge would be the only effective way to improve the WECC and the coordinated development of economy, society, and environment in Liaoning.

  11. Hover flight control of helicopter using optimal control theory

    Directory of Open Access Journals (Sweden)

    Ahmed ABOULFTOUH

    2015-09-01

    Full Text Available This paper represents the optimal control theory and its application to the full scale helicopters. Generally the control of a helicopter is a hard task, because its system is very nonlinear, coupled and sensitive to the control inputs and external disturbances which might destabilize the system. As a result of these instabilities, it is essential to use a control process that helps to improve the systems performance, confirming stability and robustness. The main objective of this part is to develop a control system design technique using Linear Quadratic Regulator (LQR to stabilize the helicopter near hover flight. In order to achieve this objective, firstly, the nonlinear model of the helicopter is linearized using small disturbance theory. The linear optimal control theory is applied to the linearized state space model of the helicopter to design the LQR controller. To clarify robustness of the controller, the effects of external wind gusts and mass change are taken into concern. Wind gusts are taken as disturbances in all directions which are simulated as a sine wave. Many simulations were made to validate and verify the response of the linear controller of the helicopter. The results show that the use of an optimal control process as LQR is a good solution for MIMO helicopter system, achieving a good stabilization and refining the final behavior of the helicopter and handling the external wind gusts disturbances as shown in the different simulations.

  12. A NASTRAN Vibration Model of the AH-1G Helicopter Airframe. Volume 2

    Science.gov (United States)

    1974-06-01

    finite ele - ment model is explained. The NASTRAN input data deck serves as a major portion of the documentation. **y ii UNCLASSIFIED SECjBlTV...xttX’S.ujet&etrt.LiixtxiXrt *u el nt % ft JJ t t -L r r. T z ’,’TZ;~zzzz.v.zrz.zzxrz**. z z z z z z. ? * z t 9 * T...rtOi\\tA7 ^«>i/,*-»^’***(7>O^**e0’^OrtO^ #3’ — 0*’N*’"— — «O^O-^ÄOOO« Ö K m >g ■»»n — #(*■«■# — ^fg^ oiDO -«*-»- « CO (B ’ *#^ ^i O

  13. Efficient fault diagnosis of helicopter gearboxes

    Science.gov (United States)

    Chin, H.; Danai, K.; Lewicki, D. G.

    1993-01-01

    Application of a diagnostic system to a helicopter gearbox is presented. The diagnostic system is a nonparametric pattern classifier that uses a multi-valued influence matrix (MVIM) as its diagnostic model and benefits from a fast learning algorithm that enables it to estimate its diagnostic model from a small number of measurement-fault data. To test this diagnostic system, vibration measurements were collected from a helicopter gearbox test stand during accelerated fatigue tests and at various fault instances. The diagnostic results indicate that the MVIM system can accurately detect and diagnose various gearbox faults so long as they are included in training.

  14. Evaluation of the Township Proper Carrying Capacity over Qinghai-Tibet plateau by CASA model

    Science.gov (United States)

    Wu, Chengyong; Cao, Guangchao; Xue, Huaju; Jiang, Gang; Wang, Qi; Yuan, Jie; Chen, Kelong

    2018-01-01

    The existing study of proper carrying capacity (PCC) has mostly focused on province or county administrative units, which can only macroscopically master the quantitative characteristics of PCC, but could not effectively take some animal husbandry management measures that are pertinent and operational. At town-scale, this paper used CASA model to estimate the PCC in Mongolian Autonomous County of Henan, Qinghai province, China,with serious grassland degeneration that mainly caused by overgrazing. The results showed that the PCC throughout the County was 950,417 sheep unit. For the township, the PCC of Saierlong and Duosong were the largest (247,100 sheep unit) and the smallest (82,016 sheep unit) respectively. This study will provide reference data for developing sustainable development of town-scale pasture policies and also will help to evaluate the health status of the alpine grassland ecosystem on Qinghai-Tibet plateau.

  15. Modelling PM 10 concentrations and carrying capacity associated with woodheater emissions in Launceston, Tasmania

    Science.gov (United States)

    Luhar, Ashok K.; Galbally, Ian E.; Keywood, Melita

    Launceston is one of the Australian cities most affected by particle pollution due to the use of woodheaters in the winter months, with frequent exceedences of the national standard, the National Environment Protection Measure for Ambient Air Quality (or Air NEPM in short), of 50 micrograms per cubic metre for daily PM 10 (particulate matter with an aerodynamic diameter of 10 μm or less). The main objective of the present study was to determine the woodheater carrying capacity for Launceston—the number of woodheaters that can operate in the city without exceeding the Air NEPM. For this purpose, a prognostic meteorological and air pollution model called TAPM is used, coupled to a gridded woodheater PM 10 emissions inventory. The latter was derived using information on dwelling density, the percentage of dwellings with woodheaters, woodheater emission rates and their diurnal and seasonal variations, and the proportions of compliant/non-compliant woodheaters and open fireplaces. The model simulations are performed for the year 1998, and the concentrations are scaled for previous and subsequent years using trends in woodheater numbers and types. The modelled number of exceedences of the Air NEPM for the period 1997-2004 is in good agreement with the observations. The modelling indicates that the PM 10 Air NEPM would be met in Launceston when the total number of woodheaters is 20% of the total number of dwellings, of which 76%, 18%, 6% would be compliant woodheaters, non-compliant woodheaters and open fireplaces, respectively. With the present trends in the regional woodheater profile, this should occur in the year 2007.

  16. Evaluating vacquinol-1 in rats carrying glioblastoma models RG2 and NS1.

    Science.gov (United States)

    Ahlstedt, Jonatan; Förnvik, Karolina; Zolfaghari, Shaian; Kwak, Dongoh; Hammarström, Lars G J; Ernfors, Patrik; Salford, Leif G; Redebrandt, Henrietta Nittby

    2018-02-02

    Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor, and available experimental and routine therapies result in limited survival benefits. A vulnerability of GBM cells to catastrophic vacuolization and cell death, a process termed methuosis, induced by Vacquinol-1 (VQ-1) has been described earlier. In the present study, we investigate the efficacy of VQ-1 treatment in two syngeneic rat GBM models, RG2 and NS1. VQ-1 treatment affected growth of both RG2 and NS1 cells in vitro . Intracranially, significant reduction in RG2 tumor size was observed, although no effect was seen on overall survival. No survival advantage or effect on tumor size was seen in animals carrying the NS1 models compared to untreated controls. Furthermore, immunological staining of FOXP3, CD4 and CD8 showed no marked difference in immune cell infiltrate in tumor environment following treatment. Taken together, a survival advantage of VQ-1 treatment alone could not be demonstrated here, even though some effect upon tumor size was seen. Staining for immune cell markers did not indicate that VQ-1 either reduced or increased host anti-tumor immune response.

  17. Nonlinear Feedforward Control for Wind Disturbance Rejection on Autonomous Helicopter

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; A. Danapalasingam, Kumeresan

    2010-01-01

    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...... 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....

  18. Effects of exhaust temperature on helicopter infrared signature

    International Nuclear Information System (INIS)

    Cheng-xiong, Pan; Jing-zhou, Zhang; Yong, Shan

    2013-01-01

    The effects of exhaust temperature on infrared signature (in 3–5 μm band) for a helicopter equipped with integrative infrared suppressor were numerically investigated. The internal flow of exhaust gas and the external downwash flow, as well as the mixing between exhaust gas and downwash were simulated by CFD software to determine the temperature distributions on the helicopter skin and in the exhaust plume. Based on the skin and plume temperature distributions, a forward–backward ray-tracing method was used to calculate the infrared radiation intensity from the helicopter with a narrow-band model. The results show that for a helicopter with its integrative infrared suppressor embedded inside its rear airframe, the exhaust temperature has significant influence on the plume radiation characteristics, while the helicopter skin radiation intensity has little impact. When the exhaust temperature is raised from 900 K to 1200 K, the plume radiation intensity in 3–5 μm band is increased by about 100%, while the skin radiation intensity is increased by only about 5%. In general, the effects of exhaust temperature on helicopter infrared radiation intensity are mainly concentrated on plume, especially obvious for a lower skin emissivity case. -- Highlights: ► The effect of exhaust temperature on infrared signature for a helicopter is numerically investigated. ► The impact of exhaust temperature on helicopter skin temperature is revealed. ► The impact of exhaust temperature on plume radiation characteristics is revealed. ► The impact of exhaust temperature on helicopter skin radiation is revealed. ► The impact of exhaust temperature on helicopter's total infrared radiation intensity is revealed

  19. Carrying Capacity Model Applied to Coastal Ecotourism of Baluran National Park, Indonesia

    Science.gov (United States)

    Armono, H. D.; Rosyid, D. M.; Nuzula, N. I.

    2017-07-01

    The resources of Baluran National Park have been used for marine and coastal ecotourism. The increasing number of visitors has led to the increasing of tourists and its related activities. This condition will cause the degradation of resources and the welfare of local communities. This research aims to determine the sustainability of coastal ecotourism management by calculating the effective number of tourists who can be accepted. The study uses the concept of tourism carrying capacity, consists the ecological environment, economic, social and physical carrying capacity. The results of the combined carrying capacity analysis in Baluran National Park ecotourism shows that the number of 3.288 people per day (151.248 tourists per year) is the maximum number of accepted tourists. The current number of tourist arrivals is only 241 people per day (87.990 tourists per year) which is far below the carrying capacity.

  20. 78 FR 70202 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-11-25

    ... Airworthiness Directives; Eurocopter France Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... France (Eurocopter) Model AS350B, BA, B1, B2, B3, D, AS355E, F, F1, F2, and N [[Page 70203

  1. Robust Adaptive Integral Backstepping Control of a 3-DOF Helicopter

    Directory of Open Access Journals (Sweden)

    Zheng Fang

    2012-09-01

    Full Text Available Unmanned aerial vehicles have enormous potential applications in military and civil fields. A Quanser's 3-DOF helicopter is a simplified and benchmark experimental model for validating the effectiveness of various flight control algorithms. The attitude control of the 3-DOF helicopter is a challenging task since the helicopter is an under-actuated system with strong coupling and model uncertainty characteristics. In this paper, an adaptive integral backstepping algorithm is proposed to realize robust control of the 3-DOF helicopter. The proposed control algorithm can estimate model uncertainties online and improve the robustness of the control system. Simulation and experiment results demonstrate that the proposed algorithm performs well in tracking and under model uncertainties.

  2. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    A spatial planning act was introduced inIndonesia 1992 and renewed in 2008. It emphasised the planning role of decentralised authorities. The spatial planning act covers both spatial and environmental issues. It defines the concept of carrying capacity and includes definitions of supportive....../cities. Four different sectors (water, food production, waste, and forests) were selected as core areas for decentralised spatial planning. Indicators for SCC and ACC were identified and assessed with regard to relevance and quantifiability. For each of the indicators selected, a legal threshold or guiding...... was introduced inIndonesia 1992 and renewed in 2008. It emphasised the planning role of decentralised authorities. The spatial planning act covers both spatial and environmental issues. It defines the concept of carrying capacity and includes definitions of supportive carrying capacity (SCC) and assimilative...

  3. Simulating effectiveness of helicopter evasive manoeuvres to RPG attack

    Science.gov (United States)

    Anderson, D.; Thomson, D. G.

    2010-04-01

    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.

  4. Carrying capacity models should not use fixed prey density thresholds : a plea for using more tools of behavioural ecology

    NARCIS (Netherlands)

    van Gils, JA; Edelaar, P; Escudero, G; Piersma, T

    Earlier studies have developed models of carrying capacity to predict the number of animals a certain area can support. These models assume that resources are not renewed after consumption ('standing stock' models), and that the initial number of prey and the rate of prey consumption determine the

  5. Calculation of One-dimensional Forward Modelling of Helicopter-borne Electromagnetic Data and a Sensitivity Matrix Using Fast Hankel Transforms

    Directory of Open Access Journals (Sweden)

    Abolfazl Asadian

    2014-06-01

    Full Text Available The helicopter-borne electromagnetic (HEM frequency-domain exploration method is an airborne electromagnetic (AEM technique that is widely used for vast and rough areas for resistivity imaging. The vast amount of digitized data flowing from the HEM method requires an efficient and accurate inversion algorithm. Generally, the inverse modelling of HEM data in the first step requires a precise and efficient technique provided by a forward modelling algorithm. The exact calculation of the sensitivity matrix or Jacobian is also of the utmost importance. As such, the main objective of this study is to design an efficient algorithm for the forward modelling of HEM frequency-domain data for the configuration of horizontal coplanar (HCP coils using fast Hankel transforms (FHTs. An attempt is also made to use an analytical approach to derive the required equations for the Jacobian matrix. To achieve these goals, an elaborated algorithm for the simultaneous calculation of the forward computation and sensitivity matrix is provided. Finally, using two synthetic models, the accuracy of the calculations of the proposed algorithm is verified. A comparison indicates that the obtained results of forward modelling are highly consistent with those reported in Simon et al. (2009 for a four-layer model. Furthermore, the comparison of the results for the sensitivity matrix for a two-layer model with those obtained from software is being used by the BGR Centre in Germany, showing that the proposed algorithm enjoys a high degree of accuracy in calculating this matrix.

  6. Specifying the Role of Exposure to Violence and Violent Behavior on Initiation of Gun Carrying: A Longitudinal Test of Three Models of Youth Gun Carrying

    Science.gov (United States)

    Spano, Richard; Pridemore, William Alex; Bolland, John

    2012-01-01

    Two waves of longitudinal data from 1,049 African American youth living in extreme poverty are used to examine the impact of exposure to violence (Time 1) and violent behavior (Time 1) on first time gun carrying (Time 2). Multivariate logistic regression results indicate that (a) violent behavior (Time 1) increased the likelihood of initiation of…

  7. A simplified model predicting the weight of the load carrying beam in a wind turbine blade

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    2016-01-01

    Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used t...

  8. A toxicokinetic model for the carry-over of dioxins and PCBs from feed and soil to eggs

    NARCIS (Netherlands)

    Eijkeren, van J.; Zeilmaker, M.; Kan, C.A.; Traag, W.A.; Hoogenboom, L.A.P.

    2006-01-01

    A mathematical model for the kinetics of carry-over of dioxins and dioxin-like PCBs from feed mixed with contaminated oil to eggs has been developed. This model incorporates uptake of the compounds over the gut wall and their subsequent transport by blood, distribution over the body, hepatic

  9. A toxicokinetic model for the carry-over of dioxins and PCBs from feed and soil to eggs.

    NARCIS (Netherlands)

    Eijkeren, Jan C H van; Zeilmaker, Marco J; Kan, C A; Traag, Win A; Hoogenboom, L A P

    2006-01-01

    A mathematical model for the kinetics of carry-over of dioxins and dioxin-like PCBs from feed mixed with contaminated oil to eggs has been developed. This model incorporates uptake of the compounds over the gut wall and their subsequent transport by blood, distribution over the body, hepatic

  10. Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip

    Science.gov (United States)

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

    2001-01-01

    Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and loads. Four rotor configurations were tested in forward flight at advance ratios from 0.15 to 0.45 and in hover in-ground effect. The hover tip Mach number was 0.627, which is representative of a design point of 4000-ft geometric altitude and a temperature of 95 F. The baseline rotor configuration had a conventional single-element airfoil in the tip region. A second rotor configuration had a forward-slotted airfoil with a -6 deg slat, a third configuration had a forward-slotted airfoil with a -10 slat, and a fourth configuration had an aft-slotted airfoil with a 3 deg flap (trailing edge down). The results of this investigation indicate that the -6 deg slat configuration offers some performance and loads benefits over the other three configurations.

  11. 78 FR 1730 - Airworthiness Directives; Bell Helicopter Textron Inc. Helicopters

    Science.gov (United States)

    2013-01-09

    ... 205A, 205A-1, and 205B helicopters with certain starter/generator power cable assemblies (power cable... 205A, 205A-1, and 205B helicopters with starter/generator power cable assemblies (power cable... assemblies using the parts contained in starter/generator kit P/N CT205-07-94-1, perform a continuity test...

  12. Integrating remote sensing and conventional grazing/browsing models for modelling carrying capacity in southern African rangelands

    Science.gov (United States)

    Adjorlolo, C.; Botha, J. O.; Mhangara, P.; Mutanga, O.; Odindi, J.

    2014-10-01

    Woody vegetation encroachment into grasslands or bush thickening, a global phenomenon, is transforming the Southern African grassland systems into savanna-like landscapes. Estimation of woody vegetation is important to rangeland scientists and land managers for assessing its impact on grass production and calculating its grazing and browsing capacity. Assessment of grazing and browsing components is often challenging because agro-ecological landscapes of this region are largely characterized by small scale and heterogeneous land-use-land-cover patterns. In this study, we investigated the utility of high spatial resolution remotely sensing data for modelling grazing and browsing capacity at landscape level. Woody tree density or Tree Equivalents (TE) and Total Leaf Mass (LMASS) data were derived using the Biomass Estimation for Canopy Volume (BECVOL) program. The Random Forest (RF) regression algorithm was assessed to establish relationships between these variables and vegetation indices (Simple Ratio and Normalized Difference Vegetation Index), calculated using the red and near infrared bands of SPOT5. The RF analysis predicted LMASS with R2 = 0.63 and a Root Mean Square Error (RMSE) of 1256 kg/ha compared to a mean of 2291kg/ha. TE was predicted with R2 = 0.55 and a RMSE = 1614 TE/ha compared to a mean of 3746 TE/ha. Next, spatial distribution maps of LMASS/ha and TE/ha were derived using separate RF regression models. The resultant maps were then used as input data into conventional grazing and browsing capacity models to calculate grazing and browsing capacity maps for the study area. This study provides a sound platform for integrating currently available and future remote sensing satellite data into rangeland carrying capacity modelling and monitoring.

  13. 78 FR 4759 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell) Helicopters

    Science.gov (United States)

    2013-01-23

    ... installed from the time the yoke had zero hours TIS. (iii) In accordance with the rate per hour categories... these yokes, and required operators to log additional hours against the retirement life of the yokes for Model 212 helicopters conducting more than four external load lifts per hour. Since the issuance of...

  14. Optimal autorotational descent of a helicopter with control and state inequality constraints

    Science.gov (United States)

    Lee, Allan Y.

    1990-01-01

    A point-mass model of the OH-58A helicopter has been used to ascertain the autorotation profiles which minimize helicopter impact velocity while remaining within the bounds of the main rotor's collective pitch and angular speed. The optimal control strategies are comparable to those employed by pilots in autorotational landings. It is noted that a possibility exists for the reduction of the height-sink rate restriction zone of OH-58A helicopters, using optimal energy-management techniques.

  15. Model for determining the load or carrying capacity of rivers and riverbanks for recreational use

    Directory of Open Access Journals (Sweden)

    Otero, I.

    2015-12-01

    Full Text Available The aim of this article is to determine the load or functional carrying capacity for the assimilation and recovery of rivers and riverbanks by compiling information on the environment, and to assess the potential for recreation from the environmental and scenic point of view. We set out to find the most significant basis for analysing the pressures limiting carrying capacity and constraining the demand for recreational use. This methodology will help planners and legislators in their decision-making. We also propose a methodology for assessing the recreational use of riverbanks, tested in a number of sites in the Madrid Region, in terms of the satisfaction the activity produces in the users, and the load or carrying capacity of the surrounding environment. A pilot site assessment is presented as a validation of the proposed methodology.El objetivo de este artículo es, determinar la capacidad de carga o acogida funcional, de asimilación y de recuperación de los márgenes y los cursos fluviales mediante la recopilación de información del medio; el potencial recreativo se evalúa además desde un doble punto de vista: ecológico y paisajístico. La forma en que se enfoca el problema y se presenta la metodología y los resultados puede resultar de gran utilidad para planificadores y legisladores. La metodología propuesta para valorar el uso recreativo de los márgenes fluviales, se aplica a una serie de parcelas en la Comunidad de Madrid, teniendo en cuenta la satisfacción que la actividad produce en los usuarios, y la capacidad de carga o acogida del entorno en el que se desarrollan. Como resultado, se presenta la valoración de parcelas piloto, que servirían para validar la metodología propuesta. [fr] Le but de cet article est, déterminer la capacité de charge ou réception fonctionnelle, l’assimilation et rétablissement des marges et les cours de la rivière par le biais de la collecte d’informations de l’environnement: le

  16. Biomechanical modeling and load-carrying simulation of lower limb exoskeleton.

    Science.gov (United States)

    Zhu, Yanhe; Zhang, Guoan; Zhang, Chao; Liu, Gangfeng; Zhao, Jie

    2015-01-01

    This paper introduces novel modern equipment-a lower extremity exoskeleton, which can implement the mutual complement and the interaction between human intelligence and the robot's mechanical strength. In order to provide a reference for the exoskeleton structure and the drive unit, the human biomechanics were modeled and analyzed by LifeModeler and Adams software to derive each joint kinematic parameter. The control was designed to implement the zero-force interaction between human and exoskeleton. Furthermore, simulations were performed to verify the control and assist effect. In conclusion, the system scheme of lower extremity exoskeleton is demonstrated to be feasible.

  17. Helicopter rotor noise investigation during ice accretion

    Science.gov (United States)

    Cheng, Baofeng

    An investigation of helicopter rotor noise during ice accretion is conducted using experimental, theoretical, and numerical methods. This research is the acoustic part of a joint helicopter rotor icing physics, modeling, and detection project at The Pennsylvania State University Vertical Lift Research Center of Excellence (VLRCOE). The current research aims to provide acoustic insight and understanding of the rotor icing physics and investigate the feasibility of detecting rotor icing through noise measurements, especially at the early stage of ice accretion. All helicopter main rotor noise source mechanisms and their change during ice accretion are discussed. Changes of the thickness noise, steady loading noise, and especially the turbulent boundary layer - trailing edge (TBL-TE) noise due to ice accretion are identified and studied. The change of the discrete frequency noise (thickness noise and steady loading noise) due to ice accretion is calculated by using PSU-WOPWOP, an advanced rotorcraft acoustic prediction code. The change is noticeable, but too small to be used in icing detection. The small thickness noise change is due to the small volume of the accreted ice compared to that of the entire blade, although a large iced airfoil shape is used. For the loading noise calculation, two simplified methods are used to generate the loading on the rotor blades, which is the input for the loading noise calculation: 1) compact loading from blade element momentum theory, icing effects are considered by increasing the drag coefficient; and 2) pressure loading from the 2-D CFD simulation, icing effects are considered by using the iced airfoil shape. Comprehensive rotor broadband noise measurements are carried out on rotor blades with different roughness sizes and rotation speeds in two facilities: the Adverse Environment Rotor Test Stand (AERTS) facility at The Pennsylvania State University, and The University of Maryland Acoustic Chamber (UMAC). In both facilities the

  18. Modeling and data activities under the IAEA ISAM project. A resume of the activities carried out

    International Nuclear Information System (INIS)

    Torres, C.; Heilbron, P.; Lietava, P.; Little, R.; Yucelf, V.; Volckaert, G.

    2002-01-01

    This paper describes part of the work that was developed in the 3 year Co-ordinated Programme entitled Improvement of Long Term Safety Assessment Methodologies for near surface disposal facilities (ISAM) regarding the modelling and data issues on the safety assessment of near surface disposal facilities for the disposal of low and intermediate radioactive waste. (author)

  19. Optimal short range trajectories for helicopters

    Science.gov (United States)

    Slater, G. L.; Erzberger, H.

    1983-01-01

    An optimal flight path algorithm using a simplified altitude state model and an apriori climb-cruise-descent flight profile has been developed and applied to determine minimum fuel and minimum cost trajectories for a helicopter flying a fixed range trajectory. The performance model is based on standard flight manual data and is such that on-line trajectory optimization is feasible with a relatively small computer. The results show that the optimal flight path and optimal cruise altitude can represent a 10 percent fuel saving on a minimum fuel trajectory. The optimal trajectories show considerable variability due to helicopter weight, ambient winds and the relative cost trade-off between time and fuel. In general, 'reasonable' variations from the optimal velocities and cruise altitudes do not significantly degrade the optimal cost.

  20. Helicopter TEM parameters analysis and system optimization based on time constant

    Science.gov (United States)

    Xiao, Pan; Wu, Xin; Shi, Zongyang; Li, Jutao; Liu, Lihua; Fang, Guangyou

    2018-03-01

    Helicopter transient electromagnetic (TEM) method is a kind of common geophysical prospecting method, widely used in mineral detection, underground water exploration and environment investigation. In order to develop an efficient helicopter TEM system, it is necessary to analyze and optimize the system parameters. In this paper, a simple and quantitative method is proposed to analyze the system parameters, such as waveform, power, base frequency, measured field and sampling time. A wire loop model is used to define a comprehensive 'time constant domain' that shows a range of time constant, analogous to a range of conductance, after which the characteristics of the system parameters in this domain is obtained. It is found that the distortion caused by the transmitting base frequency is less than 5% when the ratio of the transmitting period to the target time constant is greater than 6. When the sampling time window is less than the target time constant, the distortion caused by the sampling time window is less than 5%. According to this method, a helicopter TEM system, called CASHTEM, is designed, and flight test has been carried out in the known mining area. The test results show that the system has good detection performance, verifying the effectiveness of the method.

  1. Methodology to carry out a sensitivity and uncertainty analysis for cross sections using a coupled model Trace-Parcs

    International Nuclear Information System (INIS)

    Reyes F, M. C.; Del Valle G, E.; Gomez T, A. M.; Sanchez E, V.

    2015-09-01

    A methodology was implemented to carry out a sensitivity and uncertainty analysis for cross sections used in a coupled model for Trace/Parcs in a transient of control rod fall of a BWR-5. A model of the reactor core for the neutronic code Parcs was used, in which the assemblies located in the core are described. Thermo-hydraulic model in Trace was a simple model, where only a component type Chan was designed to represent all the core assemblies, which it was within a single vessel and boundary conditions were established. The thermo-hydraulic part was coupled with the neutron part, first for the steady state and then a transient of control rod fall was carried out for the sensitivity and uncertainty analysis. To carry out the analysis of cross sections used in the coupled model Trace/Parcs during the transient, the Probability Density Functions for 22 parameters selected from the total of neutronic parameters that use Parcs were generated, obtaining 100 different cases for the coupled model Trace/Parcs, each one with a database of different cross sections. All these cases were executed with the coupled model, obtaining in consequence 100 different output files for the transient of control rod fall doing emphasis in the nominal power, for which an uncertainty analysis was realized at the same time generate the band of uncertainty. With this analysis is possible to observe the ranges of results of the elected responses varying the selected uncertainty parameters. The sensitivity analysis complements the uncertainty analysis, identifying the parameter or parameters with more influence on the results and thus focuses on these parameters in order to better understand their effects. Beyond the obtained results, because is not a model with real operation data, the importance of this work is to know the application of the methodology to carry out the sensitivity and uncertainty analyses. (Author)

  2. [Measuring water ecological carrying capacity with the ecosystem-service-based ecological footprint (ESEF) method: Theory, models and application].

    Science.gov (United States)

    Jiao, Wen-jun; Min, Qing-wen; Li, Wen-hua; Fuller, Anthony M

    2015-04-01

    Integrated watershed management based on aquatic ecosystems has been increasingly acknowledged. Such a change in the philosophy of water environment management requires recognizing the carrying capacity of aquatic ecosystems for human society from a more general perspective. The concept of the water ecological carrying capacity is therefore put forward, which considers both water resources and water environment, connects socio-economic development to aquatic ecosystems and provides strong support for integrated watershed management. In this paper, the authors proposed an ESEF-based measure of water ecological carrying capacity and constructed ESEF-based models of water ecological footprint and capacity, aiming to evaluate water ecological carrying capacity with footprint methods. A regional model of Taihu Lake Basin was constructed and applied to evaluate the water ecological carrying capacity in Changzhou City which located in the upper reaches of the basin. Results showed that human demand for water ecosystem services in this city had exceeded the supply capacity of local aquatic ecosystems and the significant gap between demand and supply had jeopardized the sustainability of local aquatic ecosystems. Considering aqua-product provision, water supply and pollutant absorption in an integrated way, the scale of population and economy aquatic ecosystems in Changzhou could bear only 54% of the current status.

  3. Helicopter trimming and tracking control using direct neural dynamic programming.

    Science.gov (United States)

    Enns, R; Si, Jennie

    2003-01-01

    This paper advances a neural-network-based approximate dynamic programming control mechanism that can be applied to complex control problems such as helicopter flight control design. Based on direct neural dynamic programming (DNDP), an approximate dynamic programming methodology, the control system is tailored to learn to maneuver a helicopter. The paper consists of a comprehensive treatise of this DNDP-based tracking control framework and extensive simulation studies for an Apache helicopter. A trim network is developed and seamlessly integrated into the neural dynamic programming (NDP) controller as part of a baseline structure for controlling complex nonlinear systems such as a helicopter. Design robustness is addressed by performing simulations under various disturbance conditions. All designs are tested using FLYRT, a sophisticated industrial scale nonlinear validated model of the Apache helicopter. This is probably the first time that an approximate dynamic programming methodology has been systematically applied to, and evaluated on, a complex, continuous state, multiple-input multiple-output nonlinear system with uncertainty. Though illustrated for helicopters, the DNDP control system framework should be applicable to general purpose tracking control.

  4. World helicopter market study

    Science.gov (United States)

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

    1978-01-01

    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.

  5. Helicopter Reliability Growth Evaluation

    Science.gov (United States)

    1976-04-01

    a)A LO 44LA N4 r1i H-P 1)H CD 0 4 4J ~4J N4 N t40 4-) 1 P4 t41 0 0 0 u z 0 UN 0 010 ON r- UN 0 z 4-) o 0 N O LA 0 N- mA kID - Ln W r- 0 m 1 Y L rdO Ln...growth-c~urves. Reliability gkowth measuremenht define~d by RPM :is not sutbefor ’helicopter$. When.pgrh intensity is dha ~iged. to Alter the qrdwth ratd

  6. The Application of a Phosphorus Budget Model Estimating the Carrying Capacity of Kesikköprü Dam Lake

    OpenAIRE

    PULATSÜ, Serap

    2014-01-01

    The aim of this study was to estimate the carrying capacity of Kesikköprü Dam Lake, Ankara, where cage farms for the intensive culture of rainbow trout are located. For this purpose Dillon and Rigler's phosphorus budget model was applied in a series of steps and the carrying capacity of the lake was found to be 3335 tonnes per year. This estimated value was about 10 times higher than the present production level of the lake. It seems possible to orientate the fish culture in cages in...

  7. Structural Dynamics, Stability, and Control of Helicopters

    Science.gov (United States)

    Meirovitch, L.; Hale, A. L.

    1978-01-01

    The dynamic synthesis of gyroscopic structures consisting of point-connected substructures is investigated. The objective is to develop a mathematical model capable of an adequate simulation of the modal characteristics of a helicopter using a minimum number of degrees of freedom. The basic approach is to regard the helicopter structure as an assemblage of flexible substructures. The variational equations for the perturbed motion about certain equilibrium solutions are derived. The discretized variational equations can be conveniently exhibited in matrix form, and a great deal of information about the system modal characteristics can be extracted from the coefficient matrices. The derivation of the variational equations requires a monumental amount of algebraic operations. To automate this task a symbolic manipulation program on a digital computer is developed.

  8. Development of helicopter attitude axes controlled hover flight without pilot assistance and vehicle crashes

    Science.gov (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

  9. Autonomous vertical autorotation for unmanned helicopters

    Science.gov (United States)

    Dalamagkidis, Konstantinos

    Small Unmanned Aircraft Systems (UAS) are considered the stepping stone for the integration of civil unmanned vehicles in the National Airspace System (NAS) because of their low cost and risk. Such systems are aimed at a variety of applications including search and rescue, surveillance, communications, traffic monitoring and inspection of buildings, power lines and bridges. Amidst these systems, small helicopters play an important role because of their capability to hold a position, to maneuver in tight spaces and to take off and land from virtually anywhere. Nevertheless civil adoption of such systems is minimal, mostly because of regulatory problems that in turn are due to safety concerns. This dissertation examines the risk to safety imposed by UAS in general and small helicopters in particular, focusing on accidents resulting in a ground impact. To improve the performance of small helicopters in this area, the use of autonomous autorotation is proposed. This research goes beyond previous work in the area of autonomous autorotation by developing an on-line, model-based, real-time controller that is capable of handling constraints and different cost functions. The approach selected is based on a non-linear model-predictive controller, that is augmented by a neural network to improve the speed of the non-linear optimization. The immediate benefit of this controller is that a class of failures that would otherwise result in an uncontrolled crash and possible injuries or fatalities can now be accommodated. Furthermore besides simply landing the helicopter, the controller is also capable of minimizing the risk of serious injury to people in the area. This is accomplished by minimizing the kinetic energy during the last phase of the descent. The presented research is designed to benefit the entire UAS community as well as the public, by allowing for safer UAS operations, which in turn also allow faster and less expensive integration of UAS in the NAS.

  10. 77 FR 37777 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-06-25

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... directive (AD) for all Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 C-2 helicopters. That AD currently... following new airworthiness directive (AD): 2012-12-21 Eurocopter Deutschland GMBH: Amendment 39-17101...

  11. 77 FR 37790 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-06-25

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Eurocopter Deutschland GmbH (ECD) Model EC135 helicopters. The existing EAD, which was previously sent to all... new airworthiness directive (AD): 2012-11-02 Eurocopter Deutschland GmbH: Amendment 39-17065; Docket...

  12. 77 FR 43736 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-07-26

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed... Deutschland GmbH (Eurocopter) Model MBB-BK 117 C-2 helicopters. This proposed AD is prompted by the discovery... Deutschland GmbH: Docket No. FAA-2012-0773; Directorate Identifier 2009-SW-71-AD. (a) Applicability This AD...

  13. 77 FR 27661 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-05-11

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Deutschland GmbH (ECD) model EC135 helicopters, except the EC 135 P2+ and T2+. This proposed AD was prompted...): Eurocopter Deutschland GMBH: Docket No. FAA-2012-0500; Directorate Identifier 2010-SW-014-AD. (a...

  14. 78 FR 25361 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-05-01

    ... Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... Deutschland GmbH (Eurocopter) Model MBB-BK 117 C-2 helicopters. This AD requires inspecting the long tail... directive (AD): 2013-03-18 Eurocopter Deutschland GmbH (Eurocopter): Amendment 39- 17352; Docket No. FAA...

  15. 77 FR 27659 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-05-11

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Deutschland GmbH (ECD) Model BO-105A, BO-105C, and BO-105S helicopters. This proposed AD is prompted by... Airworthiness Directive (AD): Eurocopter Deutschland GMBH: Docket No. FAA-2012-0503; Directorate Identifier 2011...

  16. 78 FR 7312 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-02-01

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed... Deutschland GmbH (Eurocopter) Model MBB-BK 117 C-2 helicopters. This proposed AD would require changing the... new Airworthiness Directive (AD): Eurocopter Deutschland GmbH: Docket No. FAA-2013-0021; Directorate...

  17. Does modern helicopter construction reduce noise exposure in helicopter rescue operations?

    Science.gov (United States)

    Küpper, Thomas; Jansing, Paul; Schöffl, Volker; van Der Giet, Simone

    2013-01-01

    During helicopter rescue operations the medical personnel are at high risk for hearing damage by noise exposure. There are two important factors to be taken into account: first, the extreme variability, with some days involving no exposure but other days with extreme exposure; second, the extreme noise levels during work outside the helicopter, e.g. during winch operations. The benefit of modern, less noisier constructions and the consequences for noise protection are still unknown. We estimated the noise exposure of the personnel for different helicopter types used during rescue operations in the Alps and in other regions of the world with special regard to the advanced types like Eurocopter EC 135 to compare the benefit of modern constructions for noise protection with earlier ones. The rescue operations over 1 year of four rescue bases in the Alps (Raron and Zermatt in Switzerland; Landeck and Innsbruck in Austria, n = 2731) were analyzed for duration of rescue operations (noise exposure). Noise levels were measured during rescue operations at defined points inside and outside the different aircraft. The setting is according to the European standard (Richtlinie 2003/10/EG Amtsblatt) and to Class 1 DIN/IEC 651. With both data sets the equivalent noise level L(eq8h) was calculated. For comparison it was assumed that all rescue operations were performed with a specific type of helicopter. Then model calculations for noise exposure by different helicopter types, such as Alouette IIIb, Alouette II 'Lama', Ecureuil AS350, Bell UH1D, Eurocopter EC135, and others were performed. Depending on modern technologies the situation for the personnel has been improved significantly. Nevertheless noise prevention, which includes noise intermissions in spare time, is essential. Medical checks of the crews by occupational medicine (e.g. 'G20' in Germany) are still mandatory.

  18. Vertebral pain in helicopter pilots

    Science.gov (United States)

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

    1980-01-01

    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.

  19. 77 FR 44110 - Special Conditions: Agusta S.p.A. Model AW139 and AB139 Helicopter, Installation of a Search and...

    Science.gov (United States)

    2012-07-27

    ... docket number [FAA-2012-0785] using any of the following methods: Federal eRegulations Portal: Go to http... malfunction or a mode having a time-critical component, the flight crew alerting system must activate early... create a hazardous deviation in the flight path or produce hazardous loads on the helicopter during...

  20. Amplifying the helicopter drift in a conformal HMD

    Science.gov (United States)

    Schmerwitz, Sven; Knabl, Patrizia M.; Lueken, Thomas; Doehler, Hans-Ullrich

    2016-05-01

    Helicopter operations require a well-controlled and minimal lateral drift shortly before ground contact. Any lateral speed exceeding this small threshold can cause a dangerous momentum around the roll axis, which may cause a total roll over of the helicopter. As long as pilots can observe visual cues from the ground, they are able to easily control the helicopter drift. But whenever natural vision is reduced or even obscured, e.g. due to night, fog, or dust, this controllability diminishes. Therefore helicopter operators could benefit from some type of "drift indication" that mitigates the influence of a degraded visual environment. Generally humans derive ego motion by the perceived environmental object flow. The visual cues perceived are located close to the helicopter, therefore even small movements can be recognized. This fact was used to investigate a modified drift indication. To enhance the perception of ego motion in a conformal HMD symbol set the measured movement was used to generate a pattern motion in the forward field of view close or on the landing pad. The paper will discuss the method of amplified ego motion drift indication. Aspects concerning impact factors like visualization type, location, gain and more will be addressed. Further conclusions from previous studies, a high fidelity experiment and a part task experiment, will be provided. A part task study will be presented that compared different amplified drift indications against a predictor. 24 participants, 15 holding a fixed wing license and 4 helicopter pilots, had to perform a dual task on a virtual reality headset. A simplified control model was used to steer a "helicopter" down to a landing pad while acknowledging randomly placed characters.

  1. 77 FR 27116 - Safety Zone, Naval Helicopter Association Reunion Helicopter Demonstration, Elizabeth River...

    Science.gov (United States)

    2012-05-09

    ...-AA00 Safety Zone, Naval Helicopter Association Reunion Helicopter Demonstration, Elizabeth River, Norfolk, VA AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is... Helicopter Association Reunion Helicopter Demonstration. This action is necessary to provide for the safety...

  2. [Ecological carrying capacity of Chinese shrimp stock enhancement in Laizhou Bay of East China based on Ecopath model].

    Science.gov (United States)

    Lin, Qun; Li, Xian-sen; Li, Zhong-yi; Jin, Xian-shi

    2013-04-01

    Stock enhancement is an important way of fishery resources conservation, which can increase the high quality fishery resources and improve the fish population structure. The study of ecological carrying capacity is the premise for the scientific implementation of stock enhancement. Based on the survey data of the fishery resources and ecological environment in Laizhou Bay from 2009 to 2010, an Ecopath mass-balance model of the Laizhou Bay ecosystem consisted of 26 functional groups was constructed, and applied to analyze the overall characteristics of the ecosystem, the trophic interrelationships, and the keystone species, and to calculate the ecological carrying capacity of Chinese shrimp enhancement. As for the overall characteristics of the ecosystem, the total primary production/total respiration (TPP/TR) was 1. 53, total primary production/total biomass (TPP/B) was 24.54, Finn' s cycling index was lower (0.07), surplus production was higher (434. 41 t km-2 a-1 ), and system connectance index was lower (0. 29), indicating that this ecosystem was at an early development stage. The analysis on the keystone species showed that Chinese shrimp was not a keystone species of this ecosystem. At present, the biomass of Chinese shrimp in the ecosystem was 0. 1143 t km-2, with a greater potential of continued enhancement. It did not exceed the ecological carrying capacity of 2. 9489 t km-2 when the biomass of the Chinese shrimp was increased by 25. 8 times.

  3. Aerodynamic analysis of a helicopter fuselage with rotating rotor head

    Science.gov (United States)

    Reß, R.; Grawunder, M.; Breitsamter, Ch.

    2015-06-01

    The present paper describes results of wind tunnel experiments obtained during a research programme aimed at drag reduction of the fuselage of a twin engine light helicopter configuration. A 1 : 5 scale model of a helicopter fuselage including a rotating rotor head and landing gear was investigated in the low-speed wind tunnel A of Technische Universität a München (TUM). The modelled parts of the helicopter induce approxiu mately 80% of the total parasite drag thus forming a major potential for shape optimizations. The present paper compares results of force and moment measurements of a baseline configuration and modified variants with an emphasis on the aerodynamic drag, lift, and yawing moment coefficients.

  4. Square tracking sensor for autonomous helicopter hover stabilization

    Science.gov (United States)

    Oertel, Carl-Henrik

    1995-06-01

    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.

  5. Robust Helicopter Stabilization in the Face of Wind Disturbance

    DEFF Research Database (Denmark)

    A. Danapalasingam, Kumeresan; Leth, John-Josef; la Cour-Harbo, Anders

    2010-01-01

    When a helicopter is required to hover with minimum deviations from a desired position without measurements of an affecting persistent wind disturbance, a robustly stabilizing control action is vital. In this paper, the stabilization of the position and translational velocity of a nonlinear...... helicopter model affected by a wind disturbance is addressed. The wind disturbance is assumed to be a sum of a fixed number of sinusoids with unknown amplitudes, frequencies and phases. An estimate of the disturbance is introduced to be adapted using state measurements for control purposes. A nonlinear...... controller is then designed based on nonlinear adaptive output regulations and robust stabilization of a chain of integrators by a saturated feedback. Simulation results show the effectiveness of the control design in the stabilization of helicopter motion and the built-in robustness of the controller...

  6. Performance of small-scale aero-derivative industrial gas turbines derived from helicopter engines

    Directory of Open Access Journals (Sweden)

    Barinyima Nkoi

    2013-12-01

    Full Text Available This paper considers comparative assessment of simple and advanced cycle small-scale aero-derivative industrial gas turbines derived from helicopter engines. More particularly, investigation was made of technical performance of the small-scale aero-derivative engine cycles based on existing and projected cycles for applications in industrial power generation, combined heat and power concept, rotating equipment driving, and/or allied processes. The investigation was done by carrying out preliminary design and performance simulation of a simple cycle (baseline two-spool small-scale aero-derivative turboshaft engine model, and some advanced counterpart aero-derivative configurations. The advanced configurations consist of recuperated and intercooled/recuperated engine cycles of same nominal power rating of 1.567 MW. The baseline model was derived from the conversion of an existing helicopter engine model. In doing so, design point and off-design point performances of the engine models were established. In comparing their performances, it was observed that to a large extent, the advanced engine cycles showed superior performance in terms of thermal efficiency, and specific fuel consumption. In numerical terms, thermal efficiencies of recuperated engine cycle, and intercooled/recuperated engine cycles, over the simple cycle at DP increased by 13.5%, and 14.5% respectively, whereas specific fuel consumption of these cycles over simple cycle at DP decreased by 12.5%, and 13% respectively. This research relied on open access public literature for data.

  7. Wind Tunnel Testing of a 120th Scale Large Civil Tilt-Rotor Model in Airplane and Helicopter Modes

    Science.gov (United States)

    Theodore, Colin R.; Willink, Gina C.; Russell, Carl R.; Amy, Alexander R.; Pete, Ashley E.

    2014-01-01

    In April 2012 and October 2013, NASA and the U.S. Army jointly conducted a wind tunnel test program examining two notional large tilt rotor designs: NASA's Large Civil Tilt Rotor and the Army's High Efficiency Tilt Rotor. The approximately 6%-scale airframe models (unpowered) were tested without rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. Measurements of all six forces and moments acting on the airframe were taken using the wind tunnel scale system. In addition to force and moment measurements, flow visualization using tufts, infrared thermography and oil flow were used to identify flow trajectories, boundary layer transition and areas of flow separation. The purpose of this test was to collect data for the validation of computational fluid dynamics tools, for the development of flight dynamics simulation models, and to validate performance predictions made during conceptual design. This paper focuses on the results for the Large Civil Tilt Rotor model in an airplane mode configuration up to 200 knots of wind tunnel speed. Results are presented with the full airframe model with various wing tip and nacelle configurations, and for a wing-only case also with various wing tip and nacelle configurations. Key results show that the addition of a wing extension outboard of the nacelles produces a significant increase in the lift-to-drag ratio, and interestingly decreases the drag compared to the case where the wing extension is not present. The drag decrease is likely due to complex aerodynamic interactions between the nacelle and wing extension that results in a significant drag benefit.

  8. Wind Tunnel Testing of a 6%-Scale Large Civil Tilt Rotor Model in Airplane and Helicopter Modes

    Science.gov (United States)

    2014-01-01

    In April 2012 and October 2013, NASA and the U.S. Army jointly conducted a wind tunnel test program examining two notional large tilt rotor designs... rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. Measurements of all six forces and moments acting on the airframe...airframe models were tested without rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. This test entry represents the first

  9. 77 FR 30232 - Airworthiness Directives; Bell Helicopter Textron Helicopters

    Science.gov (United States)

    2012-05-22

    ... that residual stresses induced during manufacturing may have contributed to the fatigue fracture of the... requires one work-hour at an average labor rate of $85 per hour, for a cost per helicopter of $85 and a... lever requires 10 work-hours at an average labor rate of $85 per hour and required parts will cost $12...

  10. 78 FR 57047 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-09-17

    ...-034-AD; Amendment 39-17541; AD 2013-16-03] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... new airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS350 and AS355 helicopters... foreign authority's AD, any incorporated-by-reference service information, the economic evaluation, any...

  11. 77 FR 54353 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-09-05

    ...; AD 2012-17-02] RIN 2120-AA64 Airworthiness Directives; Eurocopter France Helicopters AGENCY: Federal... directive (AD) for all Eurocopter France (EC) Model SA-365N, SA-365N1, SA-366G1, AS-365N2, AS 365 N3, EC...-reference service information, the economic evaluation, any comments received, and other information. The...

  12. 77 FR 50582 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-08-22

    ... France Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for Eurocopter France Model EC155B and EC155B1... this AD, any incorporated-by-reference service information, the economic evaluation, any comments...

  13. 77 FR 64706 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-10-23

    ...-064-AD; Amendment 39-17225; AD 2012-21-09] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... France (Eurocopter) Model EC225 helicopters with certain epicyclic modules installed. This AD requires... contains this AD, the economic evaluation, any comments received, and other information. The street address...

  14. 78 FR 15277 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-03-11

    ...-17363; AD 2013-04-06] RIN 2120-AA64 Airworthiness Directives; Eurocopter France Helicopters AGENCY... airworthiness directive (AD) for the Eurocopter France (Eurocopter) Model AS332C, AS332L, and AS332L1... information, the economic evaluation, any comments received, and other information. The street address for the...

  15. 78 FR 18230 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-03-26

    ...-053-AD; Amendment 39-17393; AD 2013-05-21] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... new airworthiness directive (AD) for Eurocopter France (Eurocopter) Model EC130 B4 helicopters with a...-by-reference service information, the economic evaluation, any comments received, and other...

  16. 77 FR 44118 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-07-27

    ...-056-AD; Amendment 39-17133; AD 2012-15-04] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... France (Eurocopter) Model EC155B1 helicopters with a certain automated flight control system installed....m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the economic...

  17. 78 FR 40072 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-07-03

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Eurocopter France... France (Eurocopter) Model AS332C1 and AS332L1 helicopters. This proposed AD would require replacing the... economic evaluation, any comments received, and other information. The street address for the Docket...

  18. 77 FR 54796 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-09-06

    ...-007-AD; Amendment 39-17166; AD 2012-17-03] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... new airworthiness directive (AD) for certain Eurocopter France Model AS350 helicopters. This AD...-reference service information, the economic evaluation, any comments received, and other information. The...

  19. 77 FR 56755 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-09-14

    ...-51-AD; Amendment 39-17172; AD 2012-17-09] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... new airworthiness directive (AD) for Eurocopter France Model SA341G helicopters. This AD requires... AD docket contains this AD, any incorporated-by-reference service information, the economic...

  20. 78 FR 70242 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-11-25

    ...-0984; Directorate Identifier 2013-SW-022-AD] RIN 2120-AA64 Airworthiness Directives; Eurocopter France...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for Eurocopter (Eurocopter) France Model... helicopters have been approved by the aviation authority of France and are approved for operation in the...

  1. Routing helicopters for crew exchanges on off-shore locations

    NARCIS (Netherlands)

    Sierksma, G.; Tijssen, G.A.

    This paper deals with a vehicle routing problem with split demands, namely the problem of determining a flight schedule for helicopters to off-shore platform locations for exchanging crew people employed on these platforms. The problem is formulated as an LP model and solved by means of a

  2. 77 FR 20321 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-04-04

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Deutschland GmbH (ECD) MBB-BK 117 A-3, MBB-BK 117 A-4, MBB- BK B-1, MBB-BK 117 B-2, and MBB-BK C-1 helicopters... Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-4 model. The EASA AD makes no mention of this model. The...

  3. Study on Helicopter Antitorque Device Based on Cross-Flow Fan Technology

    Directory of Open Access Journals (Sweden)

    Du Siliang

    2016-01-01

    Full Text Available In order to improve low-altitude flight security of single-rotor helicopter, an experimental model of a helicopter antitorque device is developed for wind tunnel test. The model is based on the flow control technology of the cross-flow fan (CFF. Wind tunnel tests show that the model can produce side force. It is concluded that the influence of the CFF rotating speed, the rotor collective pitch, and the forward flight speed on the side force of the model is great. At the same time, the numerical simulation calculation method of the model has been established. Good agreement between experimental and numerical side force and power shows that results of numerical solution are reliable. Therefore, the results in actual helicopter obtained from Computational Fluid Dynamics (CFD solution are acceptable. This proves that this antitorque device can be used for a helicopter.

  4. 78 FR 47531 - Airworthiness Directives; Various Restricted Category Helicopters

    Science.gov (United States)

    2013-08-06

    ... Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft (previously US Helicopters, Inc., UNC Helicopter, Inc... Helicopters, LLC; Robinson Air Crane, Inc.; San Joaquin Helicopters (previously Hawkins and Powers Aviation... Joaquin Helicopters (previously Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft (previously US...

  5. Research requirements to reduce maintenance costs of civil helicopters

    Science.gov (United States)

    Million, D. J.; Waters, K. T.

    1978-01-01

    The maintenance problems faced by the operators of civil helicopters that result in high costs are documented. Existing technology that can be applied to reduce maintenance costs and research that should be carried out were identified. Good design practice and application of existing technology were described as having a significant impact on reducing maintenance costs immediately. The research and development that have potential for long range reduction of maintenance costs are presented.

  6. Helicopter detection and classification demonstrator

    NARCIS (Netherlands)

    Koersel, A.C. van

    2000-01-01

    A technology demonstrator that detects and classifies different helicopter types automatically, was developed at TNO-FEL. The demonstrator is based on a PC, which receives its acoustic input from an all-weather microphone. The demonstrator uses commercial off-the-shelf hardware to digitize the

  7. Loads and performance data from a wind-tunnel test of model articulated helicopter rotors with 2 different blade torsional stiffnesses

    Science.gov (United States)

    Yeager, W. T., Jr.; Mantay, W. R.

    1983-01-01

    A passive means of tailoring helicopter rotor blades to improve performance and reduce loads was evaluated. The parameters investigated were blade torsional stiffness, blade section camber, and distance between blade structural elastic axis and blade tip aerodynamic center. This offset was accomplished by sweeping the tip. The investigation was conducted at advance ratios of 0.20, 0.30, and 0.40. Data are presented without analysis; however, cross referencing of performance data and harmonic loads data may be useful to the analyst for validating aeroelastic theories and design methodologies as well as for evaluating passive aeroelastic tailoring or rotor blade parameters.

  8. Sensitivity Analysis of the Army Training and Testing Area Carrying Capacity (ATTACC) Model to User-specified Starting Parameters

    National Research Council Canada - National Science Library

    Anderson, Alan

    1999-01-01

    ...) program is a methodology for estimating training and testing land carrying capacity. The methodology is used to determine land rehabilitation and maintenance costs associated with land-based training and other uses...

  9. 77 FR 42459 - Airworthiness Directives; MD Helicopters, Inc. (MDHI) Helicopters

    Science.gov (United States)

    2012-07-19

    ... 500N, 600N, and MD900 helicopters to require determining the cure date for each NOTAR fan blade tension..., DC 20590-0001. Hand Delivery: Deliver to the ``Mail'' address between 9 a.m. and 5 p.m., Monday... 900R3442009-103, and P/N 900R6442009-103, measured from the manufacturer's cure date or the date the package...

  10. Helicopter pilots' views of air traffic controller responsibilities: a mismatch.

    Science.gov (United States)

    Martin, Daniel; Nixon, Jim

    2018-02-21

    Controllers and pilots must work together to ensure safe and efficient helicopter flight within the London control zone. Subjective ratings of pilot perception of controller responsibility for five key flight tasks were obtained from thirty helicopter pilots. Three types of airspace were investigated. Results indicate that there is variation in pilot understanding of controller responsibility compared to the formal regulations that define controller responsibility. Significant differences in the perception of controller responsibility were found for the task of aircraft separation in class D airspace and along helicopter routes. Analysis of the patterns of response suggests that task type rather than the airspace type may be the key factor. Results are framed using the concept of a shared mental model. This research demonstrates that pilots flying in complex London airspace have an expectation of controller responsibility for certain flight tasks, in certain airspace types that is not supported by aviation regulation. Practitioner Summary: The responsibility for tasks during flight varies according to the flight rules used and airspace type. Helicopter pilots may attribute responsibility to controllers for tasks when controllers have no responsibility as defined by regulation. This variation between pilot perceptions of controller responsibility could affect safety within the London control zone.

  11. Management of Mass Casualties Using Doctor Helicopters and Doctor Cars.

    Science.gov (United States)

    Ohsaka, Hiromichi; Ishikawa, Kouhei; Omori, Kazuhiko; Jitsuiki, Kei; Yoshizawa, Toshihiko; Yanagawa, Youichi

    At approximately 10 o'clock in September 2015, a minibus carrying 18 people accidentally slid backwards because of a malfunctioning brake system while climbing a steep incline on Togasayama Mountain, colliding with a van (Toyota HiAce wagon) carrying 11 people that was situated behind the minibus. Togasayama Mountain is located 1 hour by car and 10 minutes by helicopter from our hospital. The minibus slid off a roadside cliff at a height of 0.5 m and rolled over after colliding with the van. There were 7 victims with yellow tags and 22 with green tags. Two Doctor Helicopters and 1 Doctor Car cooperated with the fire departments by providing medical treatments, selection of medical facilities, and dispersion transportation. In this mass casualty event, there were no mortalities, and all of the victims recovered without sequelae. The coordinated and combined use of Doctor Helicopters and Doctor Cars in addition to the activities of the fire department in response to a mass casualty event resulted in appropriate triage, medical treatments, selection of medical facilities, and dispersion transportation. Copyright © 2017 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Arbab Nighat Khizer

    2015-04-01

    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.

  13. Maximizing commonality between military and general aviation fly-by-light helicopter system designs

    Science.gov (United States)

    Enns, Russell; Mossman, David C.

    1995-05-01

    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.

  14. 78 FR 78710 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-12-27

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Deutschland GmbH (Eurocopter) Model EC135 P1, EC135 P2, EC135 P2+, EC135 T1, EC135 T2, EC135 T2+, and MBB-BK... directive (AD): 2013-21-06 Eurocopter Deutschland GmbH Helicopters: Amendment 39- 17630; Docket No. FAA-2013...

  15. Contributions to the dynamics of helicopters with active rotor controls

    Science.gov (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

  16. Stable Hovering Flight for a Small Unmanned Helicopter Using Fuzzy Control

    Directory of Open Access Journals (Sweden)

    Arbab Nighat Khizer

    2014-01-01

    Full Text Available Stable hover flight control for small unmanned helicopter under light air turbulent environment is presented. Intelligent fuzzy logic is chosen because it is a nonlinear control technique based on expert knowledge and is capable of handling sensor created noise and contradictory inputs commonly encountered in flight control. The fuzzy nonlinear control utilizes these distinct qualities for attitude, height, and position control. These multiple controls are developed using two-loop control structure by first designing an inner-loop controller for attitude angles and height and then by establishing outer-loop controller for helicopter position. The nonlinear small unmanned helicopter model used comes from X-Plane simulator. A simulation platform consisting of MATLAB/Simulink and X-Plane© flight simulator was introduced to implement the proposed controls. The main objective of this research is to design computationally intelligent control laws for hovering and to test and analyze this autopilot for small unmanned helicopter model on X-Plane under ideal and mild turbulent condition. Proposed fuzzy flight controls are validated using an X-Plane helicopter model before being embedded on actual helicopter. To show the effectiveness of the proposed fuzzy control method and its ability to cope with the external uncertainties, results are compared with a classical PD controller. Simulated results show that two-loop fuzzy controllers have a good ability to establish stable hovering for a class of unmanned rotorcraft in the presence of light turbulent environment.

  17. The application of mathematical models for the evaluation of radioactive tracer tests carried out in South Africa

    International Nuclear Information System (INIS)

    Snyman, G.C.; Smith, S.W.

    1975-12-01

    The application of mathematical models to evaluate tracer experiments is illustrated by examples of tests done in a variety of industrial plants, using radioactive tracers. Two basic models, the axial mixing model and the perfectly mixed tank model, as well as various applicational techniques, are described. It is concluded that many processes can be simulated to various degrees of accuracy by using the basic models, and that both quantitative and qualitative information can be obtained about the process [af

  18. A simple steady-state model for carry-over of aflatoxins from feed to cow's milk.

    NARCIS (Netherlands)

    Eijkeren, Jan C H van; Bakker, Martine I; Zeilmaker, Marco J

    2006-01-01

    A simple steady-state model is derived from two kinetic one-compartment models for the disposition of aflatoxin B1 (AFB1) and aflatoxin M1 (AFM1) in the lactating cow. The model relates daily intake of AFB1 in feed of dairy cattle and the cow's lactation status to resulting concentrations of AFM1 in

  19. Helicopter Noise And Noise Abatement Procedures

    Directory of Open Access Journals (Sweden)

    Borivoj Galović

    2004-03-01

    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.

  20. 77 FR 44434 - Airworthiness Directives; Various Restricted Category Helicopters

    Science.gov (United States)

    2012-07-30

    ... Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft (previously US Helicopters, Inc., UNC Helicopter, Inc..., Inc.; San Joaquin Helicopters (previously Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft..., Inc.; San Joaquin Helicopters (previously Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft...

  1. Sliding mode tracking control for miniature unmanned helicopters

    Directory of Open Access Journals (Sweden)

    Bin Xian

    2015-02-01

    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.

  2. Lift capability prediction for helicopter rotor blade-numerical evaluation

    Science.gov (United States)

    Rotaru, Constantin; Cîrciu, Ionicǎ; Luculescu, Doru

    2016-06-01

    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.

  3. Investigating a model for lecturer training that enables lecturers to plan and carry out meaningful e-learning activities

    DEFF Research Database (Denmark)

    Kjær, Christopher; Hansen, Pernille Stenkil; Christensen, Inger-Marie F.

    2014-01-01

    This paper reports on the effect of a lecturer training model in the shape of an e-learning project based on research on adult and work-based learning. A survey was conducted to explore participants’ learning experiences. Findings show high overall satisfaction, motivation and engagement. Suggest....... Suggestions for improvement include better integration of the e-learning project with other lecturer training components, supporting participants in formulating the e-learning project and providing additional opportunities for reflection and feedback....

  4. Implementation of a Helicopter Flight Simulator with Individual Blade Control

    Science.gov (United States)

    Zinchiak, Andrew G.

    2011-12-01

    Nearly all modern helicopters are designed with a swashplate-based system for control of the main rotor blades. However, the swashplate-based approach does not provide the level of redundancy necessary to cope with abnormal actuator conditions. For example, if an actuator fails (becomes locked) on the main rotor, the cyclic inputs are consequently fixed and the helicopter may become stuck in a flight maneuver. This can obviously be seen as a catastrophic failure, and would likely lead to a crash. These types of failures can be overcome with the application of individual blade control (IBC). IBC is achieved using the blade pitch control method, which provides complete authority of the aerodynamic characteristics of each rotor blade at any given time by replacing the normally rigid pitch links between the swashplate and the pitch horn of the blade with hydraulic or electronic actuators. Thus, IBC can provide the redundancy necessary for subsystem failure accommodation. In this research effort, a simulation environment is developed to investigate the potential of the IBC main rotor configuration for fault-tolerant control. To examine the applications of IBC to failure scenarios and fault-tolerant controls, a conventional, swashplate-based linear model is first developed for hover and forward flight scenarios based on the UH-60 Black Hawk helicopter. The linear modeling techniques for the swashplate-based helicopter are then adapted and expanded to include IBC. Using these modified techniques, an IBC based mathematical model of the UH-60 helicopter is developed for the purposes of simulation and analysis. The methodology can be used to model and implement a different aircraft if geometric, gravimetric, and general aerodynamic data are available. Without the kinetic restrictions of the swashplate, the IBC model effectively decouples the cyclic control inputs between different blades. Simulations of the IBC model prove that the primary control functions can be manually

  5. Full-scale crash test of a CH-47C helicopter

    Science.gov (United States)

    Castle, C. B.

    1976-01-01

    A full-scale crash test of a large troop/cargo carrying CH-47C helicopter was conducted at the Langley impact dynamics research facility. The crash test of this large helicopter was performed as part of a joint U.S. Army-NASA helicopter test program to provide dynamic structural and seat response data. The test, the procedures employed, the instrumentation, a general assessment of the resulting damage, and typical levels of accelerations experienced during the crash are reported. Various energy-absorbing seating systems for crew and troops were installed and instrumented to provide data for use in the development of design criteria for future aircraft. The crash conditions were selected to simulate known crash conditions and are representative of the 95th percentile accident environment for an autorotating helicopter. Visual examination of the crashed test specimen indicated irreparable damage to many of the structural components. The highest accelerations were recorded by the accelerometers located on the cabin floor in the aft section of the helicopter, directly above the primary impact location and on the floor of the cockpit above the secondary impact location(s).

  6. Simplified mathematical models for interpreting the results of tests carried out by labelling the whole piezometric column in water wells

    International Nuclear Information System (INIS)

    Munera, H.A.

    1974-01-01

    Approximate methods used to interpret the results of tests based on radioactive tracer dilution in a single water well by labelling the whole piezometric column are described; these simple mathematical models have been used to obtain semi-quantitative data on the apparent velocity (horizontal) in non-homogeneous aquifers with flow rates of metres daily. Measurements have also been made in a homogeneous aquifer with velocities of centimetres daily. Interpretation is based on determination of the average concentration for the various well zones; this involves recognition of a mean velocity for each region. All the tracer dilution effects that are not due to horizontal or vertical flow between two zones, i.e. convection, artificial mixing, diffusion and so on, are grouped together as a single term, which is taken arbitrarily to be proportional to the difference in concentration between the regions under consideration; its value is obtained from the experimental dilution curve. The model was applied to the solution of the three cases encountered most frequently during our measurements in Colombia: (a) when the well penetrates a permeable zone and adjacent impermeable zone; (b) when the well penetrates a permeable zone contained between impermeable regions; and (c) when the well traverses an aquifer with two adjacent zones of different permeability contained between impermeable zones. The shape of the dilution curve (logarithm of concentration versus time, usually with two or more slopes) is predicted by the model, the approximate nature of which is consistent with the fact that the method of labelling the whole piezometric column is semi-quantitative. The results obtained for measurements made when there are considerable vertical flows are apparently correct, but there is no other experimental measurement available to confirm them. (author) [es

  7. Could the local population of the Lower Rhine delta supply the Roman army? Part 2: Modelling the carrying capacity using archaeological, palaeo-ecological and geomorphological data

    NARCIS (Netherlands)

    van Dinter, M.; Kooistra, L.I.; Dütting, M.K.; van Rijn, P.; Cavallo, C.

    2014-01-01

    In this part two of a diptych of articles, we modelled and quantified the carrying capacity of the landscape and the demand and supply of the Roman army in the western Lower Rhine delta with wood and food in the period A.D. 40 - 140. The absolute volumes of the wood and food were calculated (in m³

  8. System Identification and Control Design of an Unmanned Helicopter Using a PI-MPC Controller

    Science.gov (United States)

    Le Tri, Quang; Lai, Ying-Chih

    2017-03-01

    This paper presents the study of the system identification and controller design for an unmanned helicopter using the integration of Proportional Integral (PI) and Model Predictive Control (MPC). Since the dynamic model of a helicopter is highly nonlinear and contains many uncertainties, the system identification and control are challenging and complicated. To accelerate the development, the autonomous flight and trajectory tracking of an unmanned helicopter, this study first setup a software simulation environment of the helicopter using the X-Plane flight simulator. The prediction-error minimization (PEM) and subspace methods were applied in this study to identify the dynamic model of the interested flight trim conditions. The lateral, longitudinal, heave, and yaw dynamic models were predicted by using the System Identification Toolbox of MATLAB. To enhance the stability and eliminate the uncertainty of the control system, the Integration of Proportional Integral (PI) and MPC were introduced. The developed control system was then applied to perform the trajectory tracking of a helicopter. The simulation results show that the performance of the proposed approach can track the desired trajectory.

  9. The Effects of Ambient Conditions on Helicopter Harmonic Noise Radiation: Theory and Experiment

    Science.gov (United States)

    Greenwood, Eric; Sim, Ben W.; Boyd, D. Douglas, Jr.

    2016-01-01

    The effects of ambient atmospheric conditions, air temperature and density, on rotor harmonic noise radiation are characterized using theoretical models and experimental measurements of helicopter noise collected at three different test sites at elevations ranging from sea level to 7000 ft above sea level. Significant changes in the thickness, loading, and blade-vortex interaction noise levels and radiation directions are observed across the different test sites for an AS350 helicopter flying at the same indicated airspeed and gross weight. However, the radiated noise is shown to scale with ambient pressure when the flight condition of the helicopter is defined in nondimensional terms. Although the effective tip Mach number is identified as the primary governing parameter for thickness noise, the nondimensional weight coefficient also impacts lower harmonic loading noise levels, which contribute strongly to low frequency harmonic noise radiation both in and out of the plane of the horizon. Strategies for maintaining the same nondimensional rotor operating condition under different ambient conditions are developed using an analytical model of single main rotor helicopter trim and confirmed using a CAMRAD II model of the AS350 helicopter. The ability of the Fundamental Rotorcraft Acoustics Modeling from Experiments (FRAME) technique to generalize noise measurements made under one set of ambient conditions to make accurate noise predictions under other ambient conditions is also validated.

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

    Science.gov (United States)

    2013-12-01

    complementary facilities available on both sides with respect to a variety of flying helicopter test beds ( RASCAL , BO105, EC135) and test facilities (model...helicopter and in the U.S,, this entails flight tests on AFDD’s RASCAL variable-stability helicopter. In addition, the NASA-Ames ground-based Vertical... RASCAL , and with a side-stick on DLR’s EC 135 ACT/FHS. Based on the results of these test, the following conclusions are drawn: 1. The effect of cyclic

  11. Biodistribution of modular nanotransporter carrying Auger electron emitter and targeted at melanoma cells in murine tumor model

    Science.gov (United States)

    Vorontsova, M. S.; Morozova, N. B.; Karmakova, T. A.; Rosenkranz, A. A.; Slastnikova, T. A.; Petriev, V. M.; Smoryzanova, O. A.; Tischenko, V. K.; Yakubovskaya, R. I.; Kaprin, A. D.; Sobolev, A. S.

    2017-09-01

    Recombinant modular nanotransporter containing α-melanocyte-stimulating hormone peptide sequence (MNT-MSH) as a ligand module was designed for nucleus-targeted delivery of cytotoxic agents into melanoma cells. MNT-MSH radiolabeled with Auger electron emitter (111In-NOTA-MNT-MSH) showed a high antitumor efficacy in mice bearing syngeneic melanoma after intratumoral (i.t.) injection. This study is aimed at evaluating the biodistribution of the radioconjugate in melanoma tumor model in vivo. 111In-NOTA-MNT-MSH was administered i.t. in C57Bl/6j mice bearing subcutaneously implanted B16-F1 murine melanoma cells, expressing high levels of MCR1. The tissue uptake of radioactivity was determined ex vivo by γ-counter measurements. The intravenous route of administration did not provide a desirable level of radioactivity accumulation in the tumor, possibly, due to a high uptake of the transporter in liver tissue. After i.t. administration 111In-NOTA-MNT-MSH provided a high local retention of radionuclide, ranged from 400 to 350 %ID/g within at least 48 hours post-injection. MNT containing Auger electron emitter and α-MSH peptide as vector ligand could be a promising basis for radiopharmaceutical preparations intended for melanoma treatment.

  12. Helicopter Urban Navigation Training Using Virtual Environments

    National Research Council Canada - National Science Library

    Wright, George

    2000-01-01

    .... Navigation is a means to an end. Helicopter operations, being inherently expensive and unforgiving of mistakes, are prime candidates for such innovative training techniques as virtual (3-D) fly-throughs...

  13. GIS and agent based spatial-temporal simulation modeling for assessing tourism social carrying capacity: a study on Mount Emei scenic area, China

    Science.gov (United States)

    Zhang, Renjun

    2007-06-01

    Each scenic area can sustain a specific level of acceptance of tourist development and use, beyond which further development can result in socio-cultural deterioration or a decline in the quality of the experience gained by visitors. This specific level is called carrying capacity. Social carrying capacity can be defined as the maximum level of use (in terms of numbers and activities) that can be absorbed by an area without an unacceptable decline in the quality of experience of visitors and without an unacceptable adverse impact on the society of the area. It is difficult to assess the carrying capacity, because the carrying capacity is determined by not only the number of visitors, but also the time, the type of the recreation, the characters of each individual and the physical environment. The objective of this study is to build a spatial-temporal simulation model to simulate the spatial-temporal distribution of tourists. This model is a tourist spatial behaviors simulator (TSBS). Based on TSBS, the changes of each visitor's travel patterns such as location, cost, and other states data are recoded in a state table. By analyzing this table, the intensity of the tourist use in any area can be calculated; the changes of the quality of tourism experience can be quantized and analyzed. So based on this micro simulation method the social carrying capacity can be assessed more accurately, can be monitored proactively and managed adaptively. In this paper, the carrying capacity of Mount Emei scenic area is analyzed as followed: The author selected the intensity of the crowd as the monitoring Indicators. it is regarded that longer waiting time means more crowded. TSBS was used to simulate the spatial-temporal distribution of tourists. the average of waiting time all the visitors is calculated. And then the author assessed the social carrying capacity of Mount Emei scenic area, found the key factors have impacted on social carrying capacity. The results show that the TSBS

  14. Tail Rotor Airfoils Stabilize Helicopters, Reduce Noise

    Science.gov (United States)

    2010-01-01

    Founded by former Ames Research Center engineer Jim Van Horn, Van Horn Aviation of Tempe, Arizona, built upon a Langley Research Center airfoil design to create a high performance aftermarket tail rotor for the popular Bell 206 helicopter. The highly durable rotor has a lifetime twice that of the original equipment manufacturer blade, reduces noise by 40 percent, and displays enhanced performance at high altitudes. These improvements benefit helicopter performance for law enforcement, military training, wildfire and pipeline patrols, and emergency medical services.

  15. Integrated locating of helicopter stations and helipads for wounded transfer under demand location uncertainty.

    Science.gov (United States)

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

    2017-03-01

    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.

  16. 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

    2015-01-01

    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

  17. 78 FR 56148 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-09-12

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... service information identified in this AD, contact Bell Helicopter Textron Canada Limited, 12,800 Rue de l... holidays. The AD docket contains this AD, the foreign authority's AD, the economic evaluation, any comments...

  18. 78 FR 34279 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-07

    ... Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration... to the ``Mail'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays... holidays. The AD docket contains this proposed AD, the economic evaluation, any comments received, and...

  19. 78 FR 65206 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-10-31

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone (450) 437-2862....m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the foreign...

  20. 78 FR 65202 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-10-31

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone (450) 437-2862.... and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the...

  1. 78 FR 66252 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-11-05

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... identified in this AD, contact Bell Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel... Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket...

  2. 78 FR 23114 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Helicopters

    Science.gov (United States)

    2013-04-18

    ... Textron Canada (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule... information identified in this AD, contact Bell Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir... Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket...

  3. 78 FR 65200 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-10-31

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION..., contact Bell Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone... Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains...

  4. Backstepping Controller with Intelligent Parameters Selection for Stabilization of Quadrotor Helicopter

    Directory of Open Access Journals (Sweden)

    Mohd Ariffanan Mohd Basri

    2016-07-01

    Full Text Available In this paper, the dynamic model of quadrotor helicopter has been mathematically formulated. Then, an intelligent backstepping controller (IBC is designed for the quadrotor altitude and attitude stabilization in the existence of external disturbances and measurement noise. The designed controller consists of a backstepping controller which can automatically select its parameters on-line by a fuzzy supervisory mechanism. The stability criterion for the stabilization of the quadrotor is proven by the Lyapunov theorem. Several numerical simulations using the dynamic model of a four degree of freedom (DOF quadrotor helicopter show the effectiveness of the approach. Besides, the simulation results indicate that the proposed design techniques can stabilize the quadrotor helicopter with better performance than established linear design techniques.

  5. Use of the GREAT-ER model to estimate mass fluxes of chemicals, carried into the Western Scheldt estuary from the Rupel basin

    OpenAIRE

    Schowanek, D.

    2002-01-01

    The poster illustrates the application of the GREAT-ER model to estimate the mass flux of chemicals carried from a river basin into an estuary. GREAT-ER (Geo-referenced Regional Exposure Assessment Tool for European Rivers) is a newly developed model (1999) for management and risk assessment of chemicals in river basins (see www.great-er.org). Recently the Rupel basin has been made available for use within GREAT-ER. This now allows to make a reliable estimation of the contribution of pollu...

  6. Examining the stability derivatives of a compound helicopter

    OpenAIRE

    Ferguson, Kevin; Thomson, Douglas

    2017-01-01

    Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a con...

  7. Assessment of water ecological carrying capacity under the two policies in Tieling City on the basis of the integrated system dynamics model.

    Science.gov (United States)

    Wang, Shuo; Xu, Ling; Yang, Fenglin; Wang, He

    2014-02-15

    Considering the limitation of the traditional method to assess the ecological carrying capacity and the complexity of the water ecological system, we used system dynamics, ANN, and CA-Markov to model a water ecological system. The social component was modeled according to Granger causality test by system dynamics. The natural component consists of the water resource and water environmental capacity, which were forecasted through the prediction of precipitation and change in land use cover. The interaction of the social component and the natural component mainly reflected environmental policies, such as the imposition of an environmental fee and environmental tax based on their values. Simulation results showed the different assessments on water ecological carrying capacity under the two policies. The population grew (2.9 million), and less pollution (86,632.37 t COD and 2854.5 t NH4N) was observed with the imposition of environmental tax compared with the imposition of an environmental fee (2.85 million population, 10,8381 t COD and 3543 t NH4N) at the same GDP level of 585 billion CNY in 2030. According to the causality loop, we discussed the different states under the policies and the reasons that caused the differences in water ecological carrying capacity state. According to game theory, we explained the limitation of the environmental fee policy on the basis of marginal benefit and cost. The externality was cleared up by the environmental tax policy. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Evolution of civil aeromedical helicopter aviation.

    Science.gov (United States)

    Meier, D R; Samper, E R

    1989-07-01

    The rapid increase in the use of helicopters for hospital transport during the 1980s is the culmination of several hundred years of military medical innovation. Mass battefield casualties spurred both technologic and medical changes necessary for today's sophisticated helicopter systems in use worldwide, particularly in the United States. The Napoleonic Era and the American Civil War provided the framework for the evolution of today's state-of-the-art emergency medical techniques. The use of airplanes to evacuate the wounded eventually led to using helicopters for rescue missions in World War II. The combat experiences of the United States in Korea, the British in Malaya, and the French in Indochina proved that rotary-wing aircraft were invaluable in reducing battlefield death rates. Any skepticism about the efficacy of helicopter medical evacuation was erased during the Vietnam conflict. As an integral part of the modern battlefield, these specialized aircraft became a necessity. The observations and experience of American servicemen and medical personnel in Vietnam established the foundation for the acceptance of helicopter transport in modern hospital systems.

  9. Vision based control of unmanned aerial vehicles with applications to an autonomous four-rotor helicopter, quadrotor

    Science.gov (United States)

    Altug, Erdinc

    Our work proposes a vision-based stabilization and output tracking control method for a model helicopter. This is a part of our effort to produce a rotorcraft based autonomous Unmanned Aerial Vehicle (UAV). Due to the desired maneuvering ability, a four-rotor helicopter has been chosen as the testbed. On previous research on flying vehicles, vision is usually used as a secondary sensor. Unlike previous research, our goal is to use visual feedback as the main sensor, which is not only responsible for detecting where the ground objects are but also for helicopter localization. A novel two-camera method has been introduced for estimating the full six degrees of freedom (DOF) pose of the helicopter. This two-camera system consists of a pan-tilt ground camera and an onboard camera. The pose estimation algorithm is compared through simulation to other methods, such as four-point, and stereo method and is shown to be less sensitive to feature detection errors. Helicopters are highly unstable flying vehicles; although this is good for agility, it makes the control harder. To build an autonomous helicopter, two methods of control are studied---one using a series of mode-based, feedback linearizing controllers and the other using a back-stepping control law. Various simulations with 2D and 3D models demonstrate the implementation of these controllers. We also show global convergence of the 3D quadrotor controller even with large calibration errors or presence of large errors on the image plane. Finally, we present initial flight experiments where the proposed pose estimation algorithm and non-linear control techniques have been implemented on a remote-controlled helicopter. The helicopter was restricted with a tether to vertical, yaw motions and limited x and y translations.

  10. Impact of flying qualities on mission effectiveness for helicopter air combat, volume 1

    Science.gov (United States)

    Harris, T. M.; Beerman, D. A.

    1983-01-01

    A computer simulation to investigate the impact of flying qualities on mission effectiveness is described. The objective of the study was to relate the effects of flying qualities, such as precision of flight path control and pilot workload, to the ability of a single Scout helicopter, or helicopter team, to accomplish a specified anti-armor mission successfully. The model of the actual engagement is a Monte Carlo simulation that has the capability to assess the effects of helicopter characteristics, numbers, tactics and weaponization on the force's ability to accomplish a specific mission against a specified threat as a function of realistic tactical factors. A key feature of this program is a simulation of micro-terrain features and their effects on detection, exposure, and masking for nap-of-the-earth (NOE) flight.

  11. Flight test of a digital controller used in a helicopter autoland system

    Science.gov (United States)

    Downing, David R.; Bryant, Wayne H.

    1987-01-01

    This paper describes the flight test evaluation of an advanced digital helicopter flight control system. The controller was designed using an optimal control design procedure for a fully coupled lateral and longitudinal vehicle model. Explicit integrals of the guidance error were included to produce a type 1 characteristic. Gain scheduling was used to account for changes in the vehicle dynamics. The digital controller was exercised by combining it with state estimators, a trajectory generator, and a closed-loop guidance algorithm to form a helicopter autoland system. A CH-47 tandem rotor helicopter was equipped with sensors, on-board digital flight computers, and electrohydraulic actuators. The system was exercised by automatically flying straight-in descending decelerating trajectories typcial of VFR manual landing approaches. A description of the test-ground facilities, the flight hardware and software, and the velocity and position tracking performance is included.

  12. Neural control of helicopter blade-vortex interaction noise

    Science.gov (United States)

    Glaessel, Holger; Kloeppel, Valentin; Rudolph, Stephan

    2001-06-01

    Significant reduction of helicopter blade-vortex interaction (BVI) noise is currently one of the most advanced research topics in the helicopter industry. This is due to the complex flow, the close aerodynamic and structural coupling, and the interaction of the blades with the trailing edge vortices. Analytical and numerical modeling techniques are therefore currently still far from a sufficient degree of accuracy to obtain satisfactory results using classical model based control concepts. Neural networks with a proven potential to learn nonlinear relationships implicitly encoded in a training data set are therefore an appropriate and complementary technique for the alternative design of a nonlinear controller for BVI noise reduction. For nonlinear and adaptive control different neural control strategies have been proposed. Two possible approaches, a direct and an indirect neural controller are described. In indirect neural control, the plant has to be identified first by training a network with measured data. The plant network is then used to train the controller network. On the other hand the direct control approach does not rely on an explicit plant model, instead a specific training algorithm (like reinforcement learning) uses the information gathered from interactions with the environment. In the investigation of the BVI noise phenomena, helicopter developers have undertaken substantial efforts in full scale flight tests and wind tunnel experiments. Data obtained in these experiments have been adequately preprocessed using wavelet analysis and filtering techniques and are then used in the design of a neural controller. Neural open-loop control and neural closed-loop control concepts for the BVI noise reduction problem are conceived, simulated and compared against each other in this work in the above mentioned framework.

  13. Experimental Investigation of a Helicopter Rotor Hub Flow

    Science.gov (United States)

    Reich, David

    The rotor hub system is by far the largest contributor to helicopter parasite drag and a barrier to increasing helicopter forward-flight speed and range. Additionally, the hub sheds undesirable vibration- and instability-inducing unsteady flow over the empennage. The challenges associated with rotor hub flows are discussed, including bluff body drag, interactional aerodynamics, and the effect of the turbulent hub wake on the helicopter empennage. This study was conducted in three phases to quantify model-scale rotor hub flows in water tunnels at The Pennsylvania State University Applied research lab. The first phase investigated scaling and component interaction effects on a 1:17 scale rotor hub model in the 12-inch diameter water tunnel. Effects of Reynolds number, advance ratio, and hub geometry configuration on the drag and wake shed from the rotor hub were quantified using load cell measurements and particle-image velocimetry (PIV). The second phase focused on flow visualization and measurement on a rotor hub and rotor hub/pylon geometry in the 12-inch diameter water tunnel. Stereo PIV was conducted in a cross plane downstream of the hub and flow visualization was conducted using oil paint and fluorescent dye. The third phase concentrated on high accuracy load measurement and prediction up to full-scale Reynolds number on a 1:4.25 scale model in the 48-inch diameter water tunnel. Measurements include 6 degree of freedom loads on the hub and two-component laser-Doppler velocimetry in the wake. Finally, results and conclusions are discussed, followed by recommendations for future investigations.

  14. Development and evaluation of an inverse solution technique for studying helicopter maneuverability and agility

    Science.gov (United States)

    Whalley, Matthew S.

    1991-01-01

    An inverse solution technique for determining the maximum maneuvering performance of a helicopter using smooth, pilotlike control inputs is presented. Also described is a pilot simulation experiment performed to investigate the accuracy of the solution resulting from this technique. The maneuverability and agility capability of the helicopter math model was varied by varying the pitch and roll damping, the maximum pitch and roll rate, and the maximum load-factor capability. Three maneuvers were investigated: a 180-deg turn, a longitudinal pop-up, and a lateral jink. The inverse solution technique yielded accurate predictions of pilot-in-the-loop maneuvering performance for two of the three maneuvers.

  15. The Use Of Satellite Remote Sensing And Helicopter Tem Data For The Identification And Characterization Of Contaminated Landfill Sites

    DEFF Research Database (Denmark)

    Viezzoli, Andrea; Edsen, Anders; Auken, Esben

    The present research aims at exploring an advanced methodologies to solve a serious problems, currently threatening the health of environment and populations: the illegal stocking of dangerous waste materials and the consequent contamination of soils and ground water systems. In previous studies......, satellite remote sensing has been successfully used to identify numerous candidate sites that are most likely to host waste materials. This result was the basis for further monitoring activities based on the use of an helicopter transient electromagnetic (TEM) system, to be carried out at end of April 2009......TEM will be capable of identifying the contaminated sites, and of mapping the contaminant plumes. Data will be carefully processed to decouple them from man made infrastructures, and then inverted with the Spatially Constrained Inversion (SCI) to recover a quasi 3D model of the subsurface. The integration of proximal...

  16. A comprehensive plan for helicopter drag reduction

    Science.gov (United States)

    Williams, R. M.; Montana, P. S.

    1975-01-01

    Current helicopters have parasite drag levels 6 to 10 times as great as fixed wing aircraft. The commensurate poor cruise efficiency results in a substantial degradation of potential mission capability. The paper traces the origins of helicopter drag and shows that the problem (primarily due to bluff body flow separation) can be solved by the adoption of a comprehensive research and development plan. This plan, known as the Fuselage Design Methodology, comprises both nonaerodynamic and aerodynamic aspects. The aerodynamics are discussed in detail and experimental and analytical programs are described which will lead to a solution of the bluff body problem. Some recent results of work conducted at the Naval Ship Research and Development Center (NSRDC) are presented to illustrate these programs. It is concluded that a 75-per cent reduction of helicopter drag is possible by the full implementation of the Fuselage Design Methodology.

  17. Experimental study of helicopter fuselage drag

    OpenAIRE

    Stepanov, Robert; Zherekov, Vladimir; Pakhov, Vladimir; Mikhailov, Sergey; Garipov, Aleksey; Yakubov, Walter; Barakos, George N.

    2016-01-01

    Experimental data are presented for the parasite drag of various helicopter fuselage components, such as skids, external fuel tanks, and tailplane. The experiments were conducted at the Kazan National Research Technical University (Kazan Aviation Institute) T-1K wind tunnel, investigating four versions of a fuselage similar to the Ansat helicopter. It was found that, for the range of pitch angles −10≤α≤10  deg−10≤α≤10  deg, the skids added 80% to the drag of the bare fuselage, whereas the tai...

  18. Helicopter trajectory planning using optimal control theory

    Science.gov (United States)

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

    1988-01-01

    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.

  19. Investigation of the flight mechanics simulation of a hovering helicopter

    Science.gov (United States)

    Chaimovich, M.; Rosen, A.; Rand, O.; Mansur, M. H.; Tischler, M. B.

    1992-01-01

    The flight mechanics simulation of a hovering helicopter is investigated by comparing the results of two different numerical models with flight test data for a hovering AH-64 Apache. The two models are the U.S. Army BEMAP and the Technion model. These nonlinear models are linearized by applying a numerical linearization procedure. The results of the linear models are compared with identification results in terms of eigenvalues, stability and control derivatives, and frequency responses. Detailed time histories of the responses of the complete nonlinear models, as a result of various pilots' inputs, are compared with flight test results. In addition the sensitivity of the models to various effects are also investigated. The results are discussed and problematic aspects of the simulation are identified.

  20. Examination of the low frequency limit for helicopter noise data in the Federal Aviation Administration's Aviation Environmental Design Tool and Integrated Noise Model

    Science.gov (United States)

    2010-04-19

    The Federal Aviation Administration (FAA) aircraft noise modeling tools Aviation Environmental Design Tool (AEDTc) and Integrated Noise Model (INM) do not currently consider noise below 50 Hz in their computations. This paper describes a preliminary ...

  1. Adaptive fuzzy tracking control for non-affine nonlinear yaw channel of unmanned aerial vehicle helicopter

    Directory of Open Access Journals (Sweden)

    Wenxu Yan

    2016-12-01

    Full Text Available The article deals with the problem of the yaw control of the unmanned aerial vehicle helicopter which is non-affine nonlinear by use of a novel projection-based adaptive fuzzy control approach. First, principle model and control design model of the yaw channel of the unmanned aerial vehicle helicopter are described. Then, a dynamic approximation technique is introduced to approach the non-affine model of the unmanned aerial vehicle helicopter into an affine model with variable parameters, which is applied to facilitate the design of nonlinear control scheme. Next, in the proposed controller, fuzzy controller is designed to deal with the unknown uncertainties and disturbances. Meanwhile, the projection-based adaptive law applied in fuzzy controller bounds the parameter estimation function and can also guarantee the robustness of the designed control scheme against uncertain disturbances. Moreover, the convergence and stability of the designed controller are proved by Lyapunov stability theory. Finally, the simulation results of the yaw channel of an unmanned aerial vehicle helicopter are performed to illustrate that the designed controller has good tracking performance, stability, and robustness under the condition of the time-vary uncertain disturbances.

  2. Full-Scale Crash Test and Finite Element Simulation of a Composite Prototype Helicopter

    Science.gov (United States)

    Jackson, Karen E.; Fasanella, Edwin L.; Boitnott, Richard L.; Lyle, Karen H.

    2003-01-01

    A full-scale crash test of a prototype composite helicopter was performed at the Impact Dynamics Research Facility at NASA Langley Research Center in 1999 to obtain data for validation of a finite element crash simulation. The helicopter was the flight test article built by Sikorsky Aircraft during the Advanced Composite Airframe Program (ACAP). The composite helicopter was designed to meet the stringent Military Standard (MIL-STD-1290A) crashworthiness criteria and was outfitted with two crew and two troop seats and four anthropomorphic dummies. The test was performed at 38-ft/s vertical and 32.5-ft/s horizontal velocity onto a rigid surface. An existing modal-vibration model of the Sikorsky ACAP helicopter was converted into a model suitable for crash simulation. A two-stage modeling approach was implemented and an external user-defined subroutine was developed to represent the complex landing gear response. The crash simulation was executed with a nonlinear, explicit transient dynamic finite element code. Predictions of structural deformation and failure, the sequence of events, and the dynamic response of the airframe structure were generated and the numerical results were correlated with the experimental data to validate the simulation. The test results, the model development, and the test-analysis correlation are described.

  3. 77 FR 75073 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-12-19

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Supplemental notice... proposed airworthiness directive (AD) for Eurocopter Deutschland GmbH (Eurocopter) Model BO-105A, BO- 105C... airworthiness directive (AD): Eurocopter Deutschland GmbH: Docket No. FAA-2011-1285; Directorate Identifier 2010...

  4. 78 FR 52410 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-08-23

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Deutschland GmbH (ECD) Model BO-105A, BO-105C, BO-105S, BO- 105LS A-1, BO-105LS A-3, MBB-BK 117 A-1, MBB-BK... Deutschland (Germany). Comments We gave the public the opportunity to participate in developing this AD, but...

  5. 78 FR 37446 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-06-21

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Deutschland GmbH (Eurocopter) Model BO-105A, BO-105C, BO- 105S, BO-105LS A-1, BO-105LS A-3, EC135 P1, EC135 P2... new airworthiness directive (AD): 2013-11-15 Eurocopter Deutschland GmbH: Amendment 39-17475; Docket...

  6. 77 FR 69558 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-11-20

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... airworthiness directive (AD) for Eurocopter Deutschland GmbH (ECD) Model EC135 P1, EC135 P2, EC135 P2+, EC135 T1...-53 Eurocopter Deutschland GMBH (ECD): Amendment 39-17254; Docket No. FAA-2012-1188; Directorate...

  7. 77 FR 42958 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2012-07-23

    ... airworthiness directive (AD) for Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 (all versions) and BO-105LS... tail rotor pitch link and subsequent loss of control of the helicopter. DATES: This AD becomes... improperly swaged spherical bearing on the pitch link, which could result in loss of tail rotor control and...

  8. A New Framework For Helicopter Vibration Suppression; Time-Periodic System Identification and Controller Design

    Science.gov (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

  9. Hub and pylon fairing integration for helicopter drag reduction

    Science.gov (United States)

    Martin, D. M.; Mort, R. W.; Squires, P. K.; Young, L. A.

    1991-01-01

    The results of testing hub and pylon fairings mounted on a one-fifth scale helicopter with the goal of reducing parasite drag are presented. Lift, drag, and pitching moment, as well as side force and yawing moment, were measured. The primary objective of the test was to validate the drag reduction capability of integrated hub and pylon configurations in the aerodynamic environment produced by a rotating hub in forward flight. In addition to the baseline helicopter without fairings, three hub fairings and three pylon fairings were tested in various combinations. The three hub fairings tested reflect two different conceptual design approaches to implementing an integrated fairing configuration on an actual aircraft. The design philosophy is discussed in detail and comparisons are made between the wind tunnel models and potential full-scale prototypes. The data show that model drag can be reduced by as much as 20.8 percent by combining a small hub fairing with circular arc upper and flat lower surfaces and a nontapered 34-percent thick pylon fairing. Aerodynamic effects caused by the fairings, which may have a significant impact on static longitudinal and directional stability, were observed. The results support previous research which showed that the greatest reduction in model drag is achieved if the hub and pylon fairings are integrated with minimum gap between the two.

  10. Helicopter Propwash Dislodges Few Spruce Budworms

    Science.gov (United States)

    Daniel T. Jennings; Mark W. Houseweart; Mark W. Houseweart

    1986-01-01

    Propwash treatments from a low-flying Bell 47-G2 helicopter dislodged few spruce budworm larvae and pupae from host balsam-fir trees. After propwash treatments, both larval-pupal densities on branch samples and in drop-tray collections near the ground were not significantly different between treated and control plots. Significantly more larvae were found in the lower...

  11. Feasibility of Helicopter Support Seek Frost.

    Science.gov (United States)

    1980-05-01

    DOO pet month plus $300-500 per flying hour. Due to the remoteness of the logistics nodes a backup helicopter would seem necessary at each node. The...into the copter’s RNAV of the ground equipment and all aircraft rolling down a moderate incline. This unit. (A DHC-8 Twin Otter also partici- have to

  12. Performance Measurement in Helicopter Training and Operations.

    Science.gov (United States)

    Prophet, Wallace W.

    For almost 15 years, HumRRO Division No. 6 has conducted an active research program on techniques for measuring the flight performance of helicopter trainees and pilots. This program addressed both the elemental aspects of flying (i.e., maneuvers) and the mission- or goal-oriented aspects. A variety of approaches has been investigated, with the…

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

    International Nuclear Information System (INIS)

    Gomes, Jose O.; Woods, David D.; Carvalho, Paulo V.R.; Huber, Gilbert J.; Borges, Marcos R.S.

    2009-01-01

    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

  14. Impaired action potential initiation in GABAergic interneurons causes hyperexcitable networks in an epileptic mouse model carrying a human Na(V)1.1 mutation.

    Science.gov (United States)

    Hedrich, Ulrike B S; Liautard, Camille; Kirschenbaum, Daniel; Pofahl, Martin; Lavigne, Jennifer; Liu, Yuanyuan; Theiss, Stephan; Slotta, Johannes; Escayg, Andrew; Dihné, Marcel; Beck, Heinz; Mantegazza, Massimo; Lerche, Holger

    2014-11-05

    Mutations in SCN1A and other ion channel genes can cause different epileptic phenotypes, but the precise mechanisms underlying the development of hyperexcitable networks are largely unknown. Here, we present a multisystem analysis of an SCN1A mouse model carrying the NaV1.1-R1648H mutation, which causes febrile seizures and epilepsy in humans. We found a ubiquitous hypoexcitability of interneurons in thalamus, cortex, and hippocampus, without detectable changes in excitatory neurons. Interestingly, somatic Na(+) channels in interneurons and persistent Na(+) currents were not significantly changed. Instead, the key mechanism of interneuron dysfunction was a deficit of action potential initiation at the axon initial segment that was identified by analyzing action potential firing. This deficit increased with the duration of firing periods, suggesting that increased slow inactivation, as recorded for recombinant mutated channels, could play an important role. The deficit in interneuron firing caused reduced action potential-driven inhibition of excitatory neurons as revealed by less frequent spontaneous but not miniature IPSCs. Multiple approaches indicated increased spontaneous thalamocortical and hippocampal network activity in mutant mice, as follows: (1) more synchronous and higher-frequency firing was recorded in primary neuronal cultures plated on multielectrode arrays; (2) thalamocortical slices examined by field potential recordings revealed spontaneous activities and pathological high-frequency oscillations; and (3) multineuron Ca(2+) imaging in hippocampal slices showed increased spontaneous neuronal activity. Thus, an interneuron-specific generalized defect in action potential initiation causes multisystem disinhibition and network hyperexcitability, which can well explain the occurrence of seizures in the studied mouse model and in patients carrying this mutation. Copyright © 2014 the authors 0270-6474/14/3414874-16$15.00/0.

  15. Active structural acoustic control of helicopter interior multifrequency noise using input-output-based hybrid control

    Science.gov (United States)

    Ma, Xunjun; Lu, Yang; Wang, Fengjiao

    2017-09-01

    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.

  16. Full-Scale Crash Test of an MD-500 Helicopter

    Science.gov (United States)

    Littell, Justin

    2011-01-01

    A full-scale crash test was successfully conducted in March 2010 of an MD-500 helicopter at NASA Langley Research Center s Landing and Impact Research Facility. The reasons for conducting this test were threefold: 1 To generate data to be used with finite element computer modeling efforts, 2 To study the crashworthiness features typically associated with a small representative helicopter, and 3 To compare aircraft response to data collected from a previously conducted MD-500 crash test, which included an externally deployable energy absorbing (DEA) concept. Instrumentation on the airframe included accelerometers on various structural components of the airframe; and strain gages on keel beams, skid gear and portions of the skin. Three Anthropomorphic Test Devices and a specialized Human Surrogate Torso Model were also onboard to collect occupant loads for evaluation with common injury risk criteria. This paper presents background and results from this crash test conducted without the DEA concept. These results showed accelerations of approximately 30 to 50 g on the airframe at various locations, little energy attenuation through the airframe, and moderate to high probability of occupant injury for a variety of injury criteria.

  17. Gust-Tunnel Investigation of the Effect of a Sharp-Edge Gust on the Flapwise Blade Bending Moments of a Model Helicopter Rotor

    National Research Council Canada - National Science Library

    Maglieri, Domenic

    1955-01-01

    Preliminary investigations have been made in the Langley gust tunnel to determine the effects of a sharp-edge vertical gust on the blade flapwise vibratory bending moments of small model rotors having...

  18. Helicopter fuselage drag - combined computational fluid dynamics and experimental studies

    Science.gov (United States)

    Batrakov, A.; Kusyumov, A.; Mikhailov, S.; Pakhov, V.; Sungatullin, A.; Valeev, M.; Zherekhov, V.; Barakos, G.

    2015-06-01

    In this paper, wind tunnel experiments are combined with Computational Fluid Dynamics (CFD) aiming to analyze the aerodynamics of realistic fuselage configurations. A development model of the ANSAT aircraft and an early model of the AKTAI light helicopter were employed. Both models were tested at the subsonic wind tunnel of KNRTU-KAI for a range of Reynolds numbers and pitch and yaw angles. The force balance measurements were complemented by particle image velocimetry (PIV) investigations for the cases where the experimental force measurements showed substantial unsteadiness. The CFD results were found to be in fair agreement with the test data and revealed some flow separation at the rear of the fuselages. Once confidence on the CFD method was established, further modifications were introduced to the ANSAT-like fuselage model to demonstrate drag reduction via small shape changes.

  19. The 22Rv1 prostate cancer cell line carries mixed genetic ancestry: Implications for prostate cancer health disparities research using pre-clinical models.

    Science.gov (United States)

    Woods-Burnham, Leanne; Basu, Anamika; Cajigas-Du Ross, Christina K; Love, Arthur; Yates, Clayton; De Leon, Marino; Roy, Sourav; Casiano, Carlos A

    2017-12-01

    Understanding how biological factors contribute to prostate cancer (PCa) health disparities requires mechanistic functional analysis of specific genes or pathways in pre-clinical cellular and animal models of this malignancy. The 22Rv1 human prostatic carcinoma cell line was originally derived from the parental CWR22R cell line. Although 22Rv1 has been well characterized and used in numerous mechanistic studies, no racial identifier has ever been disclosed for this cell line. In accordance with the need for racial diversity in cancer biospecimens and recent guidelines by the NIH on authentication of key biological resources, we sought to determine the ancestry of 22RV1 and authenticate previously reported racial identifications for four other PCa cell lines. We used 29 established Ancestry Informative Marker (AIM) single nucleotide polymorphisms (SNPs) to conduct DNA ancestry analysis and assign ancestral proportions to a panel of five PCa cell lines that included 22Rv1, PC3, DU145, MDA-PCa-2b, and RC-77T/E. We found that 22Rv1 carries mixed genetic ancestry. The main ancestry proportions for this cell line were 0.41 West African (AFR) and 0.42 European (EUR). In addition, we verified the previously reported racial identifications for PC3 (0.73 EUR), DU145 (0.63 EUR), MDA-PCa-2b (0.73 AFR), and RC-77T/E (0.74 AFR) cell lines. Considering the mortality disparities associated with PCa, which disproportionately affect African American men, there remains a burden on the scientific community to diversify the availability of biospecimens, including cell lines, for mechanistic studies on potential biological mediators of these disparities. This study is beneficial by identifying another PCa cell line that carries substantial AFR ancestry. This finding may also open the door to new perspectives on previously published studies using this cell line. © 2017 Wiley Periodicals, Inc.

  20. Experimental determination and chemical modelling of radiolytic processes at the spent fuel/water interface. Experiments carried out in carbonate solutions in absence and presence of chloride

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Jordi; Cera, Esther; Grive, Mireia; Duro, Lara [Enviros Spain SL (Spain); Eriksen, Trygve [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Nuclear Chemistry

    2003-01-01

    We report on the recent experimental and modelling results of a research programme that started in 1995. The aim has been to understand the kinetic and thermodynamic processes that control the radiolytic generation of oxidants and reductants at the spent fuel water interface and their consequences for spent fuel matrix stability and radionuclide release. This has been done by carrying out well-controlled dissolution experiments of PWR Ringhals spent fuel fragments in an initially anoxic closed system and by using different solution compositions. Experimental series started with several tests carried out with deionised water as solvent, in a second phase experiments were conducted with 10 mM bicarbonate solutions. New experimental series were set up during the last two years by using the same bicarbonate content in solutions with varying NaCl concentrations in order to ascertain the role of this ligand on the radiolytic products and its consequence for radionuclide release. The selected NaCl concentrations are in the range of 0.1 to 10 mM. Experimental data shows that uranium dissolution at early contact times is controlled by the oxidation of the UO{sub 2} matrix. This process controls the co-dissolution of most of the analysed radionuclides, including Sr, Mo, Tc, Np and surprisingly enough, Cs. In the overall the release rates for U and the matrix associated radionuclides are in the range of 10{sup -6} moles/day with a clear decreasing trend with exposure time and after 2 years the initial release rates have decreased down to 3x10{sup -8} moles/day. The solubility of the released actinides appears to be limited by the formation of An(IV) hydroxide phases, although Np concentrations in solution did not reach solubility levels during the time intervals of the present tests. No secondary solid phase appears to control the solubility of the rest of the elements.

  1. An approach to regional wetland digital elevation model development using a differential global positioning system and a custom-built helicopter-based surveying system

    Science.gov (United States)

    Jones, J.W.; Desmond, G.B.; Henkle, C.; Glover, R.

    2012-01-01

    Accurate topographic data are critical to restoration science and planning for the Everglades region of South Florida, USA. They are needed to monitor and simulate water level, water depth and hydroperiod and are used in scientific research on hydrologic and biologic processes. Because large wetland environments and data acquisition challenge conventional ground-based and remotely sensed data collection methods, the United States Geological Survey (USGS) adapted a classical data collection instrument to global positioning system (GPS) and geographic information system (GIS) technologies. Data acquired with this instrument were processed using geostatistics to yield sub-water level elevation values with centimetre accuracy (??15 cm). The developed database framework, modelling philosophy and metadata protocol allow for continued, collaborative model revision and expansion, given additional elevation or other ancillary data. ?? 2012 Taylor & Francis.

  2. Design of fault tolerant control system for individual blade control helicopters

    Science.gov (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

  3. Kinetic analysis of elastomeric lag damper for helicopter rotors

    Science.gov (United States)

    Liu, Yafang; Wang, Jidong; Tong, Yan

    2018-02-01

    The elastomeric lag dampers suppress the ground resonance and air resonance that play a significant role in the stability of the helicopter. In this paper, elastomeric lag damper which is made from silicone rubber is built. And a series of experiments are conducted on this elastomeric lag damper. The stress-strain curves of elastomeric lag dampers employed shear forces at different frequency are obtained. And a finite element model is established based on Burgers model. The result of simulation and tests shows that the simple, linear model will yield good predictions of damper energy dissipation and it is adequate for predicting the stress-strain hysteresis loop within the operating frequency and a small-amplitude oscillation.

  4. Stability Analysis of the Slowed-Rotor Compound Helicopter Configuration

    Science.gov (United States)

    Floros, Matthew W.; Johnson, Wayne

    2007-01-01

    The stability and control of rotors at high advance ratio are considered. Teetering, articulated, gimbaled, and rigid hub types are considered for a compound helicopter (rotor and fixed wing). Stability predictions obtained using an analytical rigid flapping blade analysis, a rigid blade CAMRAD II model, and an elastic blade CAMRAD II model are compared. For the flapping blade analysis, the teetering rotor is the most stable, showing no instabilities up to an advance ratio of 3 and a Lock number of 18. A notional elastic blade model of a teetering rotor is unstable at an advance ratio of 1.5, independent of pitch frequency. Analysis of the trim controls and blade flapping shows that for small positive collective pitch, trim can be maintained without excessive control input or flapping angles.

  5. An experimental test of stroke recovery by implanting a hyaluronic acid hydrogel carrying a Nogo receptor antibody in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jun [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Tian Weiming [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Hou Shaoping [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Xu Qunyuan [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Spector, Myron [Tissue Engineering, VA Boston Healthcare System, Harvard Medical School, Boston, MA (United States); Cui Fuzhai [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2007-12-15

    The objective of the study was to determine the effects of a hyaluronic-acid-based (HA-based) hydrogel implant, carrying a polyclonal antibody to the Nogo-66 receptor (NgR), on adult rats that underwent middle cerebral artery occlusion (MCAO). Behavioral tests of a forelimb-reaching task suggested that the disabled function of the impaired forelimb in this stroke model was ameliorated by the implant to a certain extent. These behavioral findings were correlated with immunohistochemical results of investigating the distribution of NgR antibody, neurofilaments (NF) and neuron-specific class III {beta}-tubulin (TuJ1) in the brain sections. The porous hydrogel functioned as a scaffold to deliver the NgR antibody, support cell migration and development. In addition, it was found NF-positive and TuJ1-positive expressions were distributed in the implanted hydrogel. Collectively, the results demonstrate the promise of the HA hydrogel as a scaffold material and the delivery vehicle of the NgR antibody for the repair of defects and the support of neural regeneration in the brain.

  6. 78 FR 40956 - Airworthiness Directives; Eurocopter Deutschland (Eurocopter) Helicopters

    Science.gov (United States)

    2013-07-09

    ... Airworthiness Directives; Eurocopter Deutschland (Eurocopter) Helicopters AGENCY: Federal Aviation... airworthiness directive (AD): 2013-12-06 Eurocopter Deutschland (Eurocopter): Amendment 39-17484; Docket No. FAA...

  7. Helicopter mission optimization study. [portable computer technology for flight optimization

    Science.gov (United States)

    Olson, J. R.

    1978-01-01

    The feasibility of using low-cost, portable computer technology to help a helicopter pilot optimize flight parameters to minimize fuel consumption and takeoff and landing noise was demonstrated. Eight separate computer programs were developed for use in the helicopter cockpit using a hand-held computer. The programs provide the helicopter pilot with the ability to calculate power required, minimum fuel consumption for both range and endurance, maximum speed and a minimum noise profile for both takeoff and landing. Each program is defined by a maximum of two magnetic cards. The helicopter pilot is required to key in the proper input parameter such as gross weight, outside air temperature or pressure altitude.

  8. A novel animal model of thymic tumour: Development of epithelial thymoma in transgenic rats carrying human T lymphocyte virus type I pX gene

    Science.gov (United States)

    Kikuchi, Kazunori; Ikeda, Hitoshi; Tsuchikawa, Takahiro; Tsuji, Takahiro; Tanaka, Satoshi; Fugo, Kazunori; Sugaya, Toshiaki; Tanaka, Yuetsu; Tateno, Masatoshi; Maruyama, Naoki; Yoshiki, Takashi

    2002-01-01

    The pX region encodes a major product of human T lymphocyte virus type I (HTLV-I) that has been implicated previously in tumour formation. To investigate the pathogenesis of pX gene in lymphoid tissues, we established a series of novel transgenic rats carrying the pX gene under the control of a rat lymphocyte-specific protein tyrosine kinase (p56lck) proximal promoter. The transgene was constructed with the −269 to +26 region of a rat p56lck proximal promoter and the pX cDNA, and was microinjected into fertilized ova of Fischer 344/jcl female rats. Six transgenic lines from 114 pups were established. Integration and expression of the transgene were detected by polymerase chain reaction (PCR) and Southern hybridization or by reverse transcriptase-PCR, northern hybridization, and immunostaining.  Thymic tumours with lethal expansion occurred in 4 of 6 transgenic lines. The tumour consisted of spindle shaped cells. Immunohistochemical and ultra-structural analysis characterized the tumour cells to as epithelial cell type, and in the tumour arose in the medulla. Therefore, the tumour is classified into predominantly epithelial and spindle cell of medullary thymoma (type A of the new World Health Organization classification), as based on the human classification. Tumor occurrence increased in proportion to levels of the pX transcription in the thymus, for each line, and sex distinction was evident regarding rates related to tumour expansion. The transgenic rat model described here is suitable as a model for analysing tumorigenesis in epithelial thymoma occurring in humans. PMID:12641821

  9. Helicopter Anti-Torque System Using Strakes

    Science.gov (United States)

    Kelley, H. L.; Wilson, J. C.; Phelps, A. E. (Inventor)

    1984-01-01

    A helicopter is disclosed with a system for controlling main-rotor torque which reduces the power and size requirements of conventional anti-torque means. The torque countering forces are generated by disrupting the main rotor downwash flowing around the fuselage. The downwash flow is separated from the fuselage surface by a strake positioned at a specified location on the fuselage. This location is determined by the particular helicopter wash pattern and fuselage configuration, generally being located between 20 deg before top dead center (TDC) and 80 deg from TDC on the fuselage side to which the main rotor blade approaches during rotation. The strake extends along the fuselage from the cabin section to the aft end and can be continuous or separated for aerodynamic surfaces such as a horizontal stabilizer.

  10. A cable detection lidar system for helicopters

    Science.gov (United States)

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

    1992-01-01

    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.

  11. NASA/FAA helicopter simulator workshop

    Science.gov (United States)

    Larsen, William E. (Editor); Randle, Robert J., Jr. (Editor); Bray, Richard S. (Editor); Zuk, John (Editor)

    1992-01-01

    A workshop was convened by the FAA and NASA for the purpose of providing a forum at which leading designers, manufacturers, and users of helicopter simulators could initiate and participate in a development process that would facilitate the formulation of qualification standards by the regulatory agency. Formal papers were presented, special topics were discussed in breakout sessions, and a draft FAA advisory circular defining specifications for helicopter simulators was presented and discussed. A working group of volunteers was formed to work with the National Simulator Program Office to develop a final version of the circular. The workshop attracted 90 individuals from a constituency of simulator manufacturers, training organizations, the military, civil regulators, research scientists, and five foreign countries.

  12. Helicopter Transparent Enclosures. Volume 1. Design Handbook

    Science.gov (United States)

    1979-01-01

    that govern whether or not a stationary object can be seeu are: Target size Target distance Background illumination Brightness contrast Atmospheric...Uliano, G. L., "Helicopter Disguise Evaluation," MASSTER Test No. 1029, Modern Army Selected Systems Test Evaluation and Review , Fort Hood, Tex., Oct...Clearance - A Review ," TR70122, Royal Aircraft Establishment, Farnborough, England, July 1970. Matusovich, C., "Chemical Rain Repellents for Windshield

  13. Flight dynamics investigation of compound helicopter configurations

    OpenAIRE

    Ferguson, Kevin; Thomson, Douglas

    2015-01-01

    Compounding has often been proposed as a method to increase the maximum speed of the helicopter. There are\\ud two common types of compounding known as wing and thrust compounding. Wing compounding offloads the\\ud rotor at high speeds delaying the onset of retreating blade stall, hence increasing the maximum achievable speed,\\ud whereas with thrust compounding, axial thrust provides additional propulsive force. There has been a resurgence\\ud of interest in the configuration due to the emergenc...

  14. Aeromechanics Analysis of a Compound Helicopter

    Science.gov (United States)

    Yeo, Hyeonsoo; Johnson, Wayne

    2006-01-01

    A design and aeromechanics investigation was conducted for a 100,000-lb compound helicopter with a single main rotor, which is to cruise at 250 knots at 4000 ft/95 deg F condition. Performance, stability, and control analyses were conducted with the comprehensive rotorcraft analysis CAMRAD II. Wind tunnel test measurements of the performance of the H-34 and UH-1D rotors at high advance ratio were compared with calculations to assess the accuracy of the analysis for the design of a high speed helicopter. In general, good correlation was obtained with the increase of drag coefficients in the reverse flow region. An assessment of various design parameters (disk loading, blade loading, wing loading) on the performance of the compound helicopter was made. Performance optimization was conducted to find the optimum twist, collective, tip speed, and taper using the comprehensive analysis. Blade twist was an important parameter on the aircraft performance and most of the benefit of slowing the rotor occurred at the initial 20 to 30% reduction of rotor tip speed. No stability issues were observed with the current design and the control derivatives did not change much with speed, but did exhibit significant coupling.

  15. Optimum Design of a Compound Helicopter

    Science.gov (United States)

    Yeo, Hyeonsoo; Johnson, Wayne

    2006-01-01

    A design and aeromechanics investigation was conducted for a 100,000-lb compound helicopter with a single main rotor, which is to cruise at 250 knots at 4000 ft/95 deg F condition. Performance, stability, and control analyses were conducted with the comprehensive rotorcraft analysis CAMRAD II. Wind tunnel test measurements of the performance of the H-34 and UH-1D rotors at high advance ratio were compared with calculations to assess the accuracy of the analysis for the design of a high speed helicopter. In general, good correlation was obtained when an increase of drag coefficients in the reverse flow region was implemented. An assessment of various design parameters (disk loading, blade loading, wing loading) on the performance of the compound helicopter was conducted. Lower wing loading (larger wing area) and higher blade loading (smaller blade chord) increased aircraft lift-to-drag ratio. However, disk loading has a small influence on aircraft lift-to-drag ratio. A rotor parametric study showed that most of the benefit of slowing the rotor occurred at the initial 20 to 30% reduction of the advancing blade tip Mach number. No stability issues were observed with the current design. Control derivatives did not change significantly with speed, but the did exhibit significant coupling.

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

    Directory of Open Access Journals (Sweden)

    Shouzhao Sheng

    2015-09-01

    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. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage

    Directory of Open Access Journals (Sweden)

    Kusyumov A.N.

    2016-01-01

    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.

  18. Properties of Carry Value Transformation

    Directory of Open Access Journals (Sweden)

    Suryakanta Pal

    2012-01-01

    Full Text Available Carry Value Transformation (CVT is a model of discrete deterministic dynamical system. In the present study, it has been proved that (1 the sum of any two nonnegative integers is the same as the sum of their CVT and XOR values. (2 the number of iterations leading to either CVT=0 or XOR=0 does not exceed the maximum of the lengths of the two addenda expressed as binary strings. A similar process of addition of modified Carry Value Transformation (MCVT and XOR requires a maximum of two iterations for MCVT to be zero. (3 an equivalence relation is shown to exist on Z×Z which divides the CV table into disjoint equivalence classes.

  19. The Adaptive Neural Network Control of Quadrotor Helicopter

    Directory of Open Access Journals (Sweden)

    A. S. Yushenko

    2017-01-01

    Full Text Available The current steady-rising interest in using the unmanned multi-rotor aerial vehicles (UMAV designed to solve a wide range of tasks is, mainly, due to their simple design and high weight-carrying capacity as compared to classical helicopter options. Unfortunately, to solve a problem of multi-copter control is complicated because of essential nonlinearity and environmental perturbations. The most widely spread PID controllers and linear-quadratic regulators do not quite well cope with this task. The need arises for the prompt adjustment of PID controller coefficients in the course of operation or their complete re-tuning in cases of changing parameters of the control object.One of the control methods under changing conditions is the use of the sliding mode. This technology enables us to reach the stabilization and proper operation of the controlled system even under accidental external exposures and when there is a lack of the reasonably accurate mathematical model of the control object. The sliding principle is to ensure the system motion in the immediate vicinity of the sliding surface in the phase space. On the other hand, the sliding mode has some essential disadvantages. The most significant one is the high-frequency jitter of the system near the sliding surface. The sliding mode also implies the complete knowledge of the system dynamics. Various methods have been proposed to eliminate these drawbacks. For example, A.G. Aissaoui’s, H. Abid’s and M. Abid’s paper describes the application of fuzzy logic to control a drive and in Lon-Chen Hung’s and Hung-Yuan Chung’s paper an artificial neural network is used for the manipulator control.This paper presents a method of the quad-copter control with the aid of a neural network controller. This method enables us to control the system without a priori information on parameters of the dynamic model of the controlled object. The main neural network is a MIMO (“Multiple Input Multiple

  20. Control of an Autonomous Radio-Controlled Helicopter in a Modified Simulation Environment Using Proportional Integral Derivative Algorithms

    National Research Council Canada - National Science Library

    Brown, Ainsmar X; Garcia, Richard D

    2008-01-01

    .... A proportional integral derivative control algorithm was modeled in MathWorks Simulink and communicates to a flight simulator modeling a physical radio-controlled helicopter. Waypoint navigation and flight-envelope testing were then systematically evaluated to the final goal of a feasible autopilot design.

  1. Modeling of combustion noise in helicopter engines

    OpenAIRE

    Livebardon, Thomas

    2015-01-01

    The growth of air traffic at the vicinity of areas at high population density imposes to make quieter aircrafts on aeronautical manufacturers.The engine noise is one of the major contributors to the overall sound levels. Furthermore, the combustion is known to be responsible for a broadband noise generation at low-frequency. The combustion noise can be put into two main mechanisms. The first one is the emission of sound pulses by the unsteady heat release of the combustion process and is call...

  2. Deflection Shape Reconstructions of a Rotating Five-blade Helicopter Rotor from TLDV Measurements

    International Nuclear Information System (INIS)

    Fioretti, A.; Castellini, P.; Tomasini, E. P.; Di Maio, D.; Ewins, D. J.

    2010-01-01

    Helicopters are aircraft machines which are subjected to high level of vibrations, mainly due to spinning rotors. These are made of two or more blades attached by hinges to a central hub, which can make the dynamic behaviour difficult to study. However, they share some common dynamic properties with the ones expected in bladed discs, thereby the analytical modelling of rotors can be performed using some assumptions as the ones adopted for the bladed discs. This paper presents results of a vibrations study performed on a scaled helicopter rotor model which was rotating at a fix rotational speed and excited by an air jet. A simplified analytical model of that rotor was also produced to help the identifications of the vibration patterns measured using a single point tracking-SLDV measurement method.

  3. Input Shaping for Helicopter Slung Load Swing Reduction

    DEFF Research Database (Denmark)

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

    2008-01-01

    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...

  4. The Helicopter Parent (Part 2): International Arrivals and Departures

    Science.gov (United States)

    Somers, Patricia; Settle, Jim

    2010-01-01

    The phenomenon of helicopter parenting has been widely reported, yet the research literature is anemic on the topic. Based on interviews and focus groups involving 190 academic and student services professionals, this article continues by discussing the social, psychological, economic, and cultural factors that influence helicoptering; exploring…

  5. Sleep and Alertness in North Sea Helicopter Operations

    NARCIS (Netherlands)

    Simons, M.; Wilschut, E.S.; Valk, P.J.L.

    2011-01-01

    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

  6. Adaptive Control System for Autonomous Helicopter Slung Load Operations

    DEFF Research Database (Denmark)

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

    2010-01-01

    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...

  7. Economic effects of noise abatement regulations on the helicopter industry.

    OpenAIRE

    Conner, Alexander Nicholson

    1982-01-01

    Approved for public release; distribution unlimited This thesis discusses the economic effects of noise abatement regulations on the helicopter industry. Increased manufacturing and operating costs from noise abatement regulations on Sikorsky's S-75 helicopter are estimated. The effects on consumer utilization are also discussed. An appendix compares two independent research studies that used weight estimating relationships and cost estimating relationships to estimate...

  8. 77 FR 43734 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-07-26

    ... intended to prevent failure of the emergency container assembly due to age and subsequent damage to the... container assembly due to age and subsequent damage to the helicopter. This condition could result in injury... AS350BA helicopters with certain AERAZUR emergency flotation gear container assemblies installed. This...

  9. Heat stress reduction of helicopter crew wearing a ventilated vest

    NARCIS (Netherlands)

    Reffeltrath, P.A.

    2006-01-01

    Background: Helicopter pilots are often exposed to periods of high heat strain, especially when wearing survival suits. Therefore, a prototype of a ventilated vest was evaluated on its capability to reduce the heat strain of helicopter pilots during a 2-h simulated flight. Hypothesis: It was

  10. Aeroelastic effects on stability and control of hingeless rotor helicopters

    Science.gov (United States)

    Celi, Roberto

    1988-01-01

    The combined effect of torsional flexibility and offset of the aerodynamic center relative to the elastic axis on the stability and control of a hingeless rotor helicopter in forward flight is studied in this paper. The aeroelastic model of the blade is based on fully coupled flap-lag-torsion equations of motion, which include kinematic nonlinearities due to moderate deflections. The equations are discretized using a finite element Galerkin method in space, and a classical Galerkin method in time. The vehicle trim calculations are coupled to the blade aeroelastic response calculations. Quasilinearization is used to compute aeroelastic stability. Reducing torsional stiffness and moving the elastic axis ahead of the aerodynamic center strongly stabilizes the phugoid mode without reducing control sensitivity. Aeroelastic stability calculations must accompany flight dynamics calculations to prevent aeroelastic instabilities that might easily go undetected.

  11. 75 FR 62639 - Air Ambulance and Commercial Helicopter Operations, Part 91 Helicopter Operations, and Part 135...

    Science.gov (United States)

    2010-10-12

    ... Resource Management (CRM), CFIT, inadvertent flight into IMC, operational control, improved access to... issued Notice 8000.293, Helicopter Emergency Medical Services Operations, addressing CRM, adherence to... decision making, failure to maintain clearance of obstacles, inadequate planning, and improper execution of...

  12. 78 FR 4762 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-01-23

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... ``Mail'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. Examining the... the Docket Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays...

  13. 78 FR 37152 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-20

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... through Friday, except Federal holidays. Examining the AD Docket You may examine the AD docket on the....m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the...

  14. 78 FR 34286 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-07

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... to the ``Mail'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays... holidays. The AD docket contains this proposed AD, the economic evaluation, any comments received, and...

  15. 78 FR 34282 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-07

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... holidays. Examining the AD Docket You may examine the AD docket on the Internet at http://www.regulations..., except Federal holidays. The AD docket contains this proposed AD, the economic evaluation, any comments...

  16. 78 FR 34280 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-07

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ] ACTION..., except Federal holidays. Examining the AD Docket You may examine the AD docket on the Internet at http... through Friday, except Federal holidays. The AD docket contains this proposed AD, the economic evaluation...

  17. 78 FR 34290 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Science.gov (United States)

    2013-06-07

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION...'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. Examining the AD Docket... Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket...

  18. Mach number scaling of helicopter rotor blade/vortex interaction noise

    Science.gov (United States)

    Leighton, Kenneth P.; Harris, Wesley L.

    1985-01-01

    A parametric study of model helicopter rotor blade slap due to blade vortex interaction (BVI) was conducted in a 5 by 7.5-foot anechoic wind tunnel using model helicopter rotors with two, three, and four blades. The results were compared with a previously developed Mach number scaling theory. Three- and four-bladed rotor configurations were found to show very good agreement with the Mach number to the sixth power law for all conditions tested. A reduction of conditions for which BVI blade slap is detected was observed for three-bladed rotors when compared to the two-bladed baseline. The advance ratio boundaries of the four-bladed rotor exhibited an angular dependence not present for the two-bladed configuration. The upper limits for the advance ratio boundaries of the four-bladed rotors increased with increasing rotational speed.

  19. Study of the Army Helicopter Design Hover Criterion Using Temperature and Pressure Altitude

    Science.gov (United States)

    2017-09-01

    Words) Ambient temperature and altitude are used to determine design points for helicopters. In this paper, pressure altitude is used to...Ground Effect; Pressure Altitude, Design Points, ACMES: Advanced Climate Modeling and Environmental Simulations 1. Abstract Ambient temperature and...of ambient air. Both compressibility and air density determine the amount of work that a rotor has to accomplish in order to propel a rotorcraft

  20. Damping augmentation of helicopter rotors using magnetorheological dampers

    Science.gov (United States)

    Zhao, Yongsheng

    This dissertation describes an investigation exploring the use of magnetorheological (MR) dampers to augment the stability of helicopter rotors. Helicopters with advanced soft in-plane rotors are susceptible to ground resonance instabilities due to the coupling of the lightly damped rotor lag modes and fuselage modes. Traditional passive lag dampers, such as hydraulic or elastomeric dampers, can be used to alleviate these instabilities. However, these passive dampers suffer from the disadvantages that they produce large damper loads in forward flight conditions. These damper forces increase fatigue loads and reduce component life. Thus, it is desirable to have lag dampers controllable or adaptable, so that the damper can apply loads only when needed. MR fluid based dampers have recently been considered for helicopter lag damping augmentation because the forces generated by these dampers can be controlled by an applied magnetic field. In this dissertation, control schemes to integrate MR dampers with helicopters are developed and the influences of the MR dampers on rotorcraft ground resonance are studied. Specifically, the MR dampers are incorporated into the ground resonance model in two ways: using a linear equivalent viscous damping and using a nonlinear damper model. The feasibility of using MR dampers to stabilize ground resonance is studied. The open loop on-off control is utilized where MR dampers are turned on over RPM where ground resonance occurs, and turned off otherwise. To further explore the damping control ability of MR dampers, the nonlinear semi-active closed loop feedback control strategies are developed: feedback linearization control and sliding mode control. The performance of the two control strategies is evaluated using two examples: to stabilize an unstable rotor and to augment the stability of a marginally stable rotor. In addition, the robustness of the closed loop control strategies is studied using two cases: damper degradation and

  1. A Comprehensive Review of Helicopter Noise Literature

    Science.gov (United States)

    1975-06-01

    over a smdlI portion of Ilh, r’o1or di .r. This; Ialinfgr hch ~avior protduves hig~hly directionatl harmonic nofac and i- 1-1na. aaaon V oki,:w a*dI:.1...anrnultis roxbustor is tho Liest coinflgurrit on from an aeotus- * heal point (if viw.Strahl t t su-gests that a drop in comibustor flow turhule-ee...helicopters. Ana- lvtical method:s, on the other hand , require a great deal of detaihled design information to use and still require some empirical

  2. Robust Control for Lateral and Longitudinal Channels of Small-Scale Unmanned Helicopters

    Directory of Open Access Journals (Sweden)

    Bao Feng

    2015-01-01

    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.

  3. A simulation study of active feedback supression of dynamic response in helicopter rotor blades

    Science.gov (United States)

    Kana, D. D.; Bessey, R. L.; Dodge, F. T.

    1975-01-01

    A parameter study is presented for active feedback control applied to a helicopter rotor blade during forward flight. The study was performed on an electromechanical apparatus which included a mechanical model rotor blade and electronic analog simulation of interaction between blade deflections and aerodynamic loading. Blade response parameters were obtained for simulated vortex impinging at the blade tip at one pulse per revolution, and for a pulse which traveled from the blade tip toward its root. Results show that the response in a 1 - 10-per-rev frequency band is diminished by the feedback action, but at the same time responses at frequencies above 10-per-rev become increasingly more prominent with increased feedback amplitude, and can even lead to instability at certain levels. It appears that the latter behavior results from limitations of the laboratory simulation apparatus, rather than genuine potential behavior for a prototype helicopter.

  4. A comparison of lightning and nuclear electromagnetic pulse response of a helicopter

    Science.gov (United States)

    Easterbrook, C. C.; Perala, R. A.

    1984-01-01

    A numerical modeling technique is utilized to investigate the response of a UH-60A helicopter to both lightning and nuclear electromagnetic pulses (NEMP). The analytical approach involves the three-dimensional time domain finite-difference solutions of Maxwell's equations. Both the external currents and charges as well as the internal electromagnetic fields and cable responses are computed. Results of the analysis indicate that, in general, the short circuit current on internal cables is larger for lightning, whereas the open-circuit voltages are slightly higher for NEMP. The lightning response is highly dependent upon the rise time of the injected current as was expected. The analysis shows that a coupling levels to cables in a helicopter are 20 to 30 dB larger than those observed in fixed-wing aircraft.

  5. Helicopter magnetic survey conducted to locate wells

    Energy Technology Data Exchange (ETDEWEB)

    Veloski, G.A.; Hammack, R.W.; Stamp, V. (Rocky Mountain Oilfield Testing Center); Hall, R. (Rocky Mountain Oilfield Testing Center); Colina, K. (Rocky Mountain Oilfield Testing Center)

    2008-07-01

    A helicopter magnetic survey was conducted in August 2007 over 15.6 sq mi at the Naval Petroleum Reserve No. 3’s (NPR-3) Teapot Dome Field near Casper, Wyoming. The survey’s purpose was to accurately locate wells drilled there during more than 90 years of continuous oilfield operation. The survey was conducted at low altitude and with closely spaced flight lines to improve the detection of wells with weak magnetic response and to increase the resolution of closely spaced wells. The survey was in preparation for a planned CO2 flood for EOR, which requires a complete well inventory with accurate locations for all existing wells. The magnetic survey was intended to locate wells missing from the well database and to provide accurate locations for all wells. The ability of the helicopter magnetic survey to accurately locate wells was accomplished by comparing airborne well picks with well locations from an intense ground search of a small test area.

  6. Research requirements to reduce civil helicopter life cycle cost

    Science.gov (United States)

    Blewitt, S. J.

    1978-01-01

    The problem of the high cost of helicopter development, production, operation, and maintenance is defined and the cost drivers are identified. Helicopter life cycle costs would decrease by about 17 percent if currently available technology were applied. With advanced technology, a reduction of about 30 percent in helicopter life cycle costs is projected. Technological and managerial deficiencies which contribute to high costs are examined, basic research and development projects which can reduce costs include methods for reduced fuel consumption; improved turbine engines; airframe and engine production methods; safety; rotor systems; and advanced transmission systems.

  7. Estimation of carrying capacity of the Gulf of Kachchh, west coast of India in relation to petroleum hydrocarbon through oil spill modeling

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; Babu, M.T.; Reddy, G.S.; Sudheesh, K.; Desa, E.; Zingde, M.D.

    devised to estimate CC using a coupled 2D hydrodynamic - oil spill model. The model was run to assess the dissolution of the oil for various meteorological and oceanographic conditions and oil characteristics. In the case of operational discharge from a...

  8. Apollo 11 Astronaut Neil Armstrong Approaches Practice Helicopter

    Science.gov (United States)

    1969-01-01

    In preparation of the nation's first lunar landing mission, Apollo 11, crew members underwent training to practice activities they would be performing during the mission. In this photograph Neil Armstrong approaches the helicopter he flew to practice landing the Lunar Module (LM) on the Moon. The Apollo 11 mission launched from the Kennedy Space Center (KSC) in Florida via the Marshall Space Flight Center (MSFC) developed Saturn V launch vehicle on July 16, 1969 and safely returned to Earth on July 24, 1969. Aboard the space craft were astronauts Neil A. Armstrong, commander; Michael Collins, Command Module (CM) pilot; and Edwin E. (Buzz) Aldrin Jr., Lunar Module (LM) pilot. The CM, 'Columbia', piloted by Collins, remained in a parking orbit around the Moon while the LM, 'Eagle'', carrying astronauts Armstrong and Aldrin, landed on the Moon. On July 20, 1969, Armstrong was the first human to ever stand on the lunar surface, followed by Aldrin. During 2½ hours of surface exploration, the crew collected 47 pounds of lunar surface material for analysis back on Earth. With the success of Apollo 11, the national objective to land men on the Moon and return them safely to Earth had been accomplished

  9. PID Control of Miniature Unmanned Helicopter Yaw System Based on RBF Neural Network

    Science.gov (United States)

    Pan, Yue; Song, Ping; Li, Kejie

    The yaw dynamics of a miniature unmanned helicopter exhibits a complex, nonlinear, time-varying and coupling dynamic behavior. In this paper, simplified yaw dynamics model of MUH in hovering or low-velocity flight mode is established. The SISO model of yaw dynamics is obtained by mechanism modeling and system identification modeling method. PID control based on RBF neural network method combines the advantages of traditional PID controller and neural network controller. It has fast response, good robustness and self-adapting ability. It is suitable to control the yaw system of MUH. Simulation results show that the control system works well with quick response, good robustness and self adaptation.

  10. Reporting Helicopter Emergency Medical Services in Major Incidents

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...

  11. The Use of Commercial Remote Sensing Predicting Helicopter Brownout Conditions

    Science.gov (United States)

    2007-09-01

    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

  12. A Computational Tool for Helicopter Rotor Noise Prediction Project

    Data.gov (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...

  13. 78 FR 54792 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Science.gov (United States)

    2013-09-06

    ..., associated with conditional revision RCe (10-04) or later'' into the RFM for helicopters equipped with screen... and ink changes as follows. Under paragraph 1, Altitude Limits, add the phrase: ``The minimum altitude...

  14. Instrument Rating Practical Test Standards for Airplane, Helicopter, Airship

    Science.gov (United States)

    1994-10-01

    The Instrument Rating Practical Test Standards (PTS) book has : been published by the Federal Aviation Administration (FAA) to : establish the standards for the instrument rating practical test for : airplanes, helicopters, and airships. FAA inspecto...

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...

  16. Robust Nonlinear Control Based on Disturbance Observer for a Small-Scale Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Amir Razzaghian

    2017-09-01

    Full Text Available A robust nonlinear controller based on disturbance observer for the trajectory tracking control of a small-scale unmanned helicopter with nonlinear structure under external disturbances and parameter uncertainties is designed. The control objective is to let the helicopter track a predefined trajectory. The proposed robust nonlinear controller is based on the backstepping sliding mode control technique which combines both the capabilities of backstepping control and sliding mode control. The control performance developed based on a time-varying disturbance observer. In order to obtain an efficient control law design, the nonlinear model of the helicopter is reformulated as an affine nonlinear system. The mathematical proof using Lyapunov stability theorem shows that the closed loop system is asymptotically stable in the presence of this controller. To verify the robustness and stability of the proposed controller, it is compared with conventional sliding mode controller. The chattering phenomenon is attenuated significantly and the tracking error is also alleviated. The simulation results confirm the desirable performance of proposed robust nonlinear controller.

  17. Hover flight control of helicopter using optimal control theory

    OpenAIRE

    Ahmed ABOULFTOUH; Gamal EL-BAYOUMI; Mohamed MADBOULI

    2015-01-01

    This paper represents the optimal control theory and its application to the full scale helicopters. Generally the control of a helicopter is a hard task, because its system is very nonlinear, coupled and sensitive to the control inputs and external disturbances which might destabilize the system. As a result of these instabilities, it is essential to use a control process that helps to improve the systems performance, confirming stability and robustness. The main objective of this part is to ...

  18. Preliminary Application of a Helicopter Toy for Environment Monitoring

    Directory of Open Access Journals (Sweden)

    Kadir Abdul

    2017-01-01

    Full Text Available This paper presents a result of an experimental study by using a helicopter toy for monitoring several environment parameters such as temperature, humidity, and air quality. A microcontroller board named Arduino was embedded in the helicopter. This board controlled various sensors. The data captured by the sensors was sent to the receiver by using a serial communication provided by a pair of XBee Pro.

  19. An Evaluation of the Instruction Carried out with Printed Laboratory Materials Designed in Accordance with 5E Model: Reflection of Light and Image on a Plane Mirror

    Science.gov (United States)

    Ayvaci, Hakan Sevki; Yildiz, Mehmet; Bakirci, Hasan

    2015-01-01

    This study employed a print laboratory material based on 5E model of constructivist learning approach to teach reflection of light and Image on a Plane Mirror. The effect of the instruction which conducted with the designed print laboratory material on academic achievements of prospective science and technology teachers and their attitudes towards…

  20. Idiopathic Syringomyelia in a Military Helicopter Pilot.

    Science.gov (United States)

    Schiemer, Anthony

    2017-10-01

    A syrinx is a fluid-filled cavity within the spinal cord. They can lead to a variety of symptoms, including limb weakness and back pain. Incidental finding of syringomyelia provides a challenge for clinicians due to the wide variety of possible symptoms. In military aviation, neurological findings in pilots can result in extensive investigation that can lead to potentially invasive management. Conversely, the potential for chronic progression of a spinal syrinx and subsequent neurological deterioration makes early identification critical. Ultimately, the discovery of a lesion may have implications for flying status and operational capability. A 25-yr-old man working as a navy Seahawk helicopter pilot presented with episodes of right arm paraesthesia and pain between the scapulae. On at least one occasion, these symptoms woke him at night. Upon magnetic resonance imaging, dilatation of the central canal in a syrinx-like pattern in the lower cervical region was noted. Neurology review suggested the finding was persistent and unlikely to be responsible for his symptoms. No surgical input was recommended. His symptoms were attributed to mild cervical spondylosis, which resolved with ongoing physiotherapy, and he was returned to flying status. This case highlights several issues involved with the incidental finding of a syringomyelia. Surgical intervention has been known to worsen symptoms. Conversely, studies have identified minimal radiological progression in cases of idiopathic syringomyelia, with fewer individuals displaying neurological deterioration. For aircrew, potentially unnecessary neurosurgical intervention poses risks to a flying career and overall operational capability.Schiemer A. Idiopathic syringomyelia in a military helicopter pilot. Aerosp Med Hum Perform. 2017; 88(10):962-965.

  1. Development of adaptive helicopter seat systems for aircrew vibration mitigation

    Science.gov (United States)

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

    2008-03-01

    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.

  2. Trajectory tracking for two-degree of freedom helicopter system using a controller-disturbance observer integrated design.

    Science.gov (United States)

    Zarei, Amin; Poutari, M Sedigh; Barakati, S Masoud

    2018-01-29

    Trajectory tracking control for helicopters, which are widely used in severe situations such as military and rescue missions, is a challenging field of research. In helicopter system, the stability problem and predefined trajectories tracking are main challenges, especially in the presence of external disturbances and dynamic model uncertainties. Hence, a robust control design is needed for tracking the desired references. There has been a lot of motivation for solving these problems with simpler methods and also reducing the couplings in the helicopter system to achieve better performance, as the presented paper attempts to fill these gaps. This paper focuses on designing control laws for two-degree of freedom helicopter system while assuring the closed-loop stability. A nonlinear disturbance observer-based control (NDOBC) is designed for attenuating the effects of exogenous disturbances. Trajectory tracking controller and nonlinear disturbance observer are formulated in the form of two linear matrix inequality (LMI) problems. The closed-loop system stability, including controller and observer, is investigated by Lyapunov theorem. The effectiveness of the proposed design for tracking the trajectories (vertical flight and pitch angle rotor blade) and disturbance estimation is verified by simulation results. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Applications of system identification methods to the prediction of helicopter stability, control and handling characteristics

    Science.gov (United States)

    Padfield, G. D.; Duval, R. K.

    1982-01-01

    A set of results on rotorcraft system identification is described. Flight measurements collected on an experimental Puma helicopter are reviewed and some notable characteristics highlighted. Following a brief review of previous work in rotorcraft system identification, the results of state estimation and model structure estimation processes applied to the Puma data are presented. The results, which were obtained using NASA developed software, are compared with theoretical predictions of roll, yaw and pitching moment derivatives for a 6 degree of freedom model structure. Anomalies are reported. The theoretical methods used are described. A framework for reduced order modelling is outlined.

  4. "You Know You Are Sick, Why Do You Carry A Pregnancy Again?" Applying the Socio-Ecological Model to Understand Barriers to PMTCT Service Utilization in Western Kenya.

    Science.gov (United States)

    Onono, Maricianah; Kwena, Zachary; Turan, Janet; Bukusi, Elizabeth A; Cohen, Craig R; Gray, Glenda E

    2015-06-01

    Throughout most of sub-Saharan Africa (SSA), prevention of mother-to-child transmission (PMTCT) services are readily available. However, PMTCT programs in SSA have had suboptimal performance compared to other regions of the world. The main objective of this study is to explore the socio-ecological and individual factors influencing the utilization of PMTCT services among HIV-positive pregnant women in western Kenya using a social ecological model as our analytical lens. Data were collected using in-depth interviews with 33 HIV-infected women attending government health facilities in rural western Kenya. Women with HIV-infected infants aged between 6 weeks to 6 months with a definitive diagnosis of HIV in the infant, as well as those with an HIV-negative test result in the infant were interviewed between November 2012 and June 2013. Coding and analysis of the transcripts followed grounded theory tenets. Coding reports were discussed in a series of meetings held among the authors. We then employed constant comparative analysis to discover dominant individual, family, society and structural determinants of PMTCT use. Barriers to women's utilization of PMTCT services fell within the broad constructs of the socio-ecological model of individual, family, society and structural determinants. Several themes cut across the different steps of PMTCT cascade and relate to different constructs of the socio-ecological model. These themes include: self-motivation, confidence and resilience, family support, absence or reduced stigma, right provider attitude and quality of health services provided. We also found out that these factors ensured enhanced maternal health and HIV negative children. The findings of this study suggest that a woman's social environment is an important determinant of MTCT. PMTCT Interventions must comprehensively address multiple factors across the different ecological levels. More research is however required for the development of multi

  5. Could the local population of the Lower Rhine delta supply the Roman army? Part 2: Modelling the carrying capacity of the delta using archaeological, palaeo-ecological and geomorphological data

    NARCIS (Netherlands)

    Kooistra, L.I.; van Dinter, M.; Dütting, M.K.; van Rijn, P.; Cavallo, C.

    2014-01-01

    In this part two of a diptych of articles, we modelled and quantified the carrying capacity of the landscape and the demand and supply of the Roman army in the western Lower Rhine delta with wood and food in the period A.D.  – . The absolute volumes of the wood and food were calculated (in m

  6. A mathematical representation of an advanced helicopter for piloted simulator investigations of control system and display variations

    Science.gov (United States)

    Aiken, E. W.

    1980-01-01

    A mathematical model of an advanced helicopter is described. The model is suitable for use in control/display research involving piloted simulation. The general design approach for the six degree of freedom equations of motion is to use the full set of nonlinear gravitational and inertial terms of the equations and to express the aerodynamic forces and moments as the reference values and first order terms of a Taylor series expansion about a reference trajectory defined as a function of longitudinal airspeed. Provisions for several different specific and generic flight control systems are included in the model. The logic required to drive various flight control and weapon delivery symbols on a pilot's electronic display is also provided. Finally, the model includes a simplified representation of low altitude wind and turbulence effects. This model was used in a piloted simulator investigation of the effects of control system and display variations for an attack helicopter mission.

  7. Liposomal Nanoparticles Carrying anti-IL6R Antibody to the Tumour Microenvironment Inhibit Metastasis in Two Molecular Subtypes of Breast Cancer Mouse Models.

    Science.gov (United States)

    Guo, Chunlei; Chen, Yanan; Gao, Wenjuan; Chang, Antao; Ye, Yujie; Shen, Wenzhi; Luo, Yunping; Yang, Shengyong; Sun, Peiqing; Xiang, Rong; Li, Na

    2017-01-01

    Tumour microenvironment (TME) contributes significantly towards potentiating the stemness and metastasis properties of cancer cells. IL6-Stat3 is one of the important cell signaling pathways in mediating the communication between tumour and immune cells. Here, we have systematically developed a novel anti-CD44 antibody-mediated liposomal nanoparticle delivery system loaded with anti-IL6R antibody, which could specifically target the TME of CD44 + breast cancer cells in different mouse models for triple negative and luminal breast cancer. This nanoparticle had an enhanced and specific tumour targeting efficacy with dramatic anti-tumour metastasis effects in syngeneic BALB/c mice bearing 4T1 cells as was in the syngeneic MMTV-PyMT mice. It inhibited IL6R-Stat3 signaling and moderated the TME, characterized by the reduced expression of genes encoding Stat3, Sox2, VEGFA, MMP-9 and CD206 in the breast tissues. Furthermore, this nanoparticle reduced the subgroups of Sox2 + and CD206 + cells in the lung metastatic foci, demonstrating its inhibitory effect on the lung metastatic niche for breast cancer stem cells. Taken together, the CD44 targeted liposomal nanoparticles encapsulating anti-IL6R antibody achieved a significant effect to inhibit the metastasis of breast cancer in different molecular subtypes of breast cancer mouse models. Our results shed light on the application of nanoparticle mediated cancer immune-therapy through targeting TME.

  8. Methodology to carry out a sensitivity and uncertainty analysis for cross sections using a coupled model Trace-Parcs; Metodologia para realizar un analisis de sensibilidad e incertidumbre para las secciones eficaces usando un modelo acoplado TRACE-PARCS

    Energy Technology Data Exchange (ETDEWEB)

    Reyes F, M. C.; Del Valle G, E. [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, Col. Lindavista, 07738 Ciudad de Mexico (Mexico); Gomez T, A. M. [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Sanchez E, V., E-mail: rf.melisa@gmail.com [Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2015-09-15

    A methodology was implemented to carry out a sensitivity and uncertainty analysis for cross sections used in a coupled model for Trace/Parcs in a transient of control rod fall of a BWR-5. A model of the reactor core for the neutronic code Parcs was used, in which the assemblies located in the core are described. Thermo-hydraulic model in Trace was a simple model, where only a component type Chan was designed to represent all the core assemblies, which it was within a single vessel and boundary conditions were established. The thermo-hydraulic part was coupled with the neutron part, first for the steady state and then a transient of control rod fall was carried out for the sensitivity and uncertainty analysis. To carry out the analysis of cross sections used in the coupled model Trace/Parcs during the transient, the Probability Density Functions for 22 parameters selected from the total of neutronic parameters that use Parcs were generated, obtaining 100 different cases for the coupled model Trace/Parcs, each one with a database of different cross sections. All these cases were executed with the coupled model, obtaining in consequence 100 different output files for the transient of control rod fall doing emphasis in the nominal power, for which an uncertainty analysis was realized at the same time generate the band of uncertainty. With this analysis is possible to observe the ranges of results of the elected responses varying the selected uncertainty parameters. The sensitivity analysis complements the uncertainty analysis, identifying the parameter or parameters with more influence on the results and thus focuses on these parameters in order to better understand their effects. Beyond the obtained results, because is not a model with real operation data, the importance of this work is to know the application of the methodology to carry out the sensitivity and uncertainty analyses. (Author)

  9. An empirical model for salt removal percentage in water under the effect of different current intensities of current carrying coil at different flow rates

    Directory of Open Access Journals (Sweden)

    Rameen S. AbdelHady

    2011-10-01

    Full Text Available The magnetic treatment of hard water is an alternative, simple approach by which the hard water that needs to be treated flows through a magnetic field. This field is created by inducing current in a coil wrapped around a pipe. Consequently some of its properties, such as total dissolved salts (TDS, conductivity (Ec and PH change. The primary purpose of hard water treatment is to decrease TDS in the incoming liquid stream. Using performance data from the application of different magnetic field densities on the different flow levels of water, empirical mathematical models were developed relating the salt removal percentage (SRP to operating flow rate and current of the coil. The obtained experimental results showed that the SRP increased with increasing the current at low flow rates (up to 0.75 ml/s.

  10. Expression Analysis of Hairpin RNA Carrying Sugarcane mosaic virus (SCMV Derived Sequences and Transgenic Resistance Development in a Model Rice Plant

    Directory of Open Access Journals (Sweden)

    Sehrish Akbar

    2017-01-01

    Full Text Available Developing transgenic resistance in monocotyledonous crops against pathogens remains a challenging area of research. Sugarcane mosaic virus (SCMV is a serious pathogen of many monocotyledonous crops including sugarcane. The objective of present study was to analyze transgenic expression of hairpin RNA (hpRNA, targeting simultaneously CP (Coat Protein and Hc-Pro (helper component-proteinase genes of SCMV, in a model rice plant. Conserved nucleotide sequences, exclusive for DAG (Aspartic acid-Alanine-Glycine and KITC (Lycine-Isoleucine-Threonine-Cysteine motifs, derived from SCMV CP and Hc-Pro genes, respectively, were fused together and assembled into the hpRNA cassette under maize ubiquitin promoter to form Ubi-hpCP:Hc-Pro construct. The same CP:Hc-Pro sequence was fused with the β-glucuronidase gene (GUS at the 3′ end under CaMV 35S promoter to develop 35S-GUS:CP:Hc-Pro served as a target reporter gene construct. When delivered into rice callus tissues by particle bombardment, the Ubi-hpCP:Hc-Pro construct induced strong silencing of 35S-GUS:CP:Hc-Pro. Transgenic rice plants, containing Ubi-hpCP:Hc-Pro construct, expressed high level of 21–24 nt small interfering RNAs, which induced specific suppression against GUS:CP:Hc-Pro delivered by particle bombardment and conferred strong resistance to mechanically inoculated SCMV. It is concluded that fusion hpRNA approach is an affordable method for developing resistance against SCMV in model rice plant and it could confer SCMV resistance when transformed into sugarcane.

  11. A passive infrared ice detection technique for helicopter applications

    Science.gov (United States)

    Dershowitz, Adam L.; Hansman, R. John, Jr.

    1991-01-01

    A technique has been developed, and successfully tested, to detect icing remotely on helicopter rotor blades. Using passive infrared (IR) thermometry it is possible to detect the warming caused by latent heat released as supercooled water freezes. During icing, the ice accretion region on the leading edge of the blade is found to be warmer than the uniced trailing edge resulting in a chordwise temperature profile characteristic of icing. Preliminary tests, using an IR Thermal video system, were conducted on a static model in the NASA Icing Research Tunnel (IRT) for a variety of wet (glaze) and dry (rime) ice conditions. A prototype detector system was built consisting of a single point IR pyrometer, and experiments were run on a small scale rotor model. Using this prototype detector, the characteristic chordwise temperature profiles were again observed for a range of icing conditions. Several signal processing methods were investigated, to allow automatic recognition of the icing signature. Additionally, several implementation issues were considered. Based on both the static and subscale rotor tests, where ice was successfully detected, the passive IR technique appears to be promising for rotor ice detection.

  12. Population growth and earth's human carrying capacity.

    Science.gov (United States)

    Cohen, J E

    1995-07-21

    Earth's capacity to support people is determined both by natural constraints and by human choices concerning economics, environment, culture (including values and politics), and demography. Human carrying capacity is therefore dynamic and uncertain. Human choice is not captured by ecological notions of carrying capacity that are appropriate for nonhuman populations. Simple mathematical models of the relation between human population growth and human carrying capacity can account for faster-than-exponential population growth followed by a slowing population growth rate, as observed in recent human history.

  13. Performance Analysis of a Utility Helicopter with Standard and Advanced Rotors

    National Research Council Canada - National Science Library

    Yeo, Hyeonsoo; Bousman, William G; Johnson, Wayne

    2002-01-01

    Flight test measurements of the performance of the UH-60 Black Hawk helicopter with both standard and advanced rotors are compared with calculations obtained using the comprehensive helicopter analysis CAMRAD II...

  14. The Impact Response of Composite Materials Involved in Helicopter Vulnerability Assessment: Literature Review - Part 2

    National Research Council Canada - National Science Library

    Resnyansky, A. D

    2006-01-01

    ... (Armed Reconnaissance Helicopter) into service. The review examines more than five hundred recent publications on the impact response of composite and cellular materials which are constituents of modern air platforms, specifically, helicopters...

  15. Flight Test Identification and Simulation of a UH-60A Helicopter and Slung Load

    National Research Council Canada - National Science Library

    Cicolani, Luigi

    2001-01-01

    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...

  16. The role of the helicopter in transportation. [technology assessment for use in civil aviation

    Science.gov (United States)

    Dajani, J. S.; Warner, D.; Epstein, D.; Obrien, J.

    1976-01-01

    A general overview is presented of the role that the helicopter plays in the current aviation scene with special emphasis on its use in the airport access function. Technological problems of present-day aircraft are discussed along with some plausible solutions. The economic and regulatory aspects of commercial helicopter operations are presented. Finally six commercial operations utilizing helicopters are reviewed and conditions that enhance the success of the helicopter in the airport access function are proposed.

  17. Helicopter Parenting: The Effect of an Overbearing Caregiving Style on Peer Attachment and Self-Efficacy

    Science.gov (United States)

    van Ingen, Daniel J.; Freiheit, Stacy R.; Steinfeldt, Jesse A.; Moore, Linda L.; Wimer, David J.; Knutt, Adelle D.; Scapinello, Samantha; Roberts, Amber

    2015-01-01

    Helicopter parenting, an observed phenomenon on college campuses, may adversely affect college students. The authors examined how helicopter parenting is related to self-efficacy and peer relationships among 190 undergraduate students ages 16 to 28 years. Helicopter parenting was associated with low self-efficacy, alienation from peers, and a lack…

  18. Flow Structures within a Helicopter Rotor Hub Wake

    Science.gov (United States)

    Elbing, Brian; Reich, David; Schmitz, Sven

    2015-11-01

    A scaled model of a notional helicopter rotor hub was tested in the 48'' Garfield Thomas Water Tunnel at the Applied Research Laboratory Penn State. The measurement suite included total hub drag and wake velocity measurements (LDV, PIV, stereo-PIV) at three downstream locations. The main objective was to understand the spatiotemporal evolution of the unsteady wake between the rotor hub and the nominal location of the empennage (tail). Initial analysis of the data revealed prominent two- and four-per-revolution fluid structures linked to geometric hub features persisting into the wake far-field. In addition, a six-per-revolution fluid structure was observed in the far-field, which is unexpected due to the lack of any hub feature with the corresponding symmetry. This suggests a nonlinear interaction is occurring within the wake to generate these structures. This presentation will provide an overview of the experimental data and analysis with particular emphasis on these six-per-revolution structures.

  19. Terfenol-D driven flaps for helicopter vibration reduction

    Science.gov (United States)

    Fenn, Ralph C.; Downer, James R.; Bushko, Dariusz A.; Gondhalekar, Vijay; Ham, Norman D.

    1996-02-01

    The utility of helicopter aviation is limited by the high vibration levels caused by the interaction of each rotor blade with the wake of preceding blades. Existing full-blade actuation using a swashplate has various problems such as insufficient bandwidth, limitations in the number of harmonics controlled, high maintenance, and lack of spanwise lift variation. These problems are avoided by the proposed flap operated, individual blade control system, which uses magnetostrictive actuation technology. Terfenol-D actuation has many advantages over competing technologies such as hydraulic systems, electric motors, and piezoelectric elements. These benefits include all-electric operation, simplicity and reliability, low mass, low voltage, and insensitivity to centripetal acceleration. A blade mounted Terfenol-D actuator was developed for the high-weight-penalty helicopter application. The optimum coil to Terfenol-D volume ratio was derived that gives the highest mechanical power output for a small actuator envelope and mass. A fixed ability to dissipate coil resistive losses is assumed. The magnetostrictive actuation system will weigh less than 1% of gross vehicle weight, and use only 0.7% of cruise power. Other required subsystems of the vibration reduction system are available from commercial sources or are described in the literature. Helicopter vibration reduction greater than 90% is predicted because of superior actuator performance and individual blade control. This magnetostrictive actuator technology will also produce future helicopter systems having lower noise and higher performance. Such advances will significantly improve the utility and competitiveness of helicopters for civilian and military transportation.

  20. Optimized direct inverse control to control altitude of a small helicopter

    Directory of Open Access Journals (Sweden)

    Suprijono Herwin

    2015-01-01

    Full Text Available In this paper, an optimization of a direct inverse control (DIC algorithm is discussed. The DIC algorithm is constructed by using a neural network that was trained to find the mathematical inverse model of the plant. In the case of a DIC to control a small helicopter as a UAV in our case, it is required to collect the flight experiment data, such as the PWM signal into servo motors, and the flight output such as the pitch, roll, yaw and the altitude. By using a real small helicopter TREX 450, the neural network based DIC model was performed with an acceptable of error, however, in order to have a better performance, an optimized neural network DIC model is proposed by retraining the neural networks DIC model using a new data generated from a determined optimal reference pathway. The experiment results show that the optimized neural networks DIC model have a better performance with lower total error rate compare with that of the un-optimized neural networks DIC model.

  1. The X-40 sub-scale technology demonstrator and its U.S. Army CH-47 Chinook helicopter mothership fly

    Science.gov (United States)

    2000-01-01

    The X-40 sub-scale technology demonstrator and its U.S. Army CH-47 Chinook helicopter mothership fly over a dry lakebed runway during a captive-carry test flight from NASA's Dryden Flight Research Center, Edwards, California. The X-40 is attached to a sling which is suspended from the CH-47 by a 110-foot-long cable during the tests, while a small parachute trails behind to provide stability. The captive carry flights are designed to verify the X-40's navigation and control systems, rigging angles for its sling, and stability and control of the helicopter while carrying the X-40 on a tether. Following a series of captive-carry flights, the X-40 made free flights from a launch altitude of about 15,000 feet above ground, gliding to a fully autonomous landing. The X-40 is an unpowered 82 percent scale version of the X-37, a Boeing-developed spaceplane designed to demonstrate various advanced technologies for development of future lower-cost access to space vehicles. The X-37 will be carried into space aboard a space shuttle and then released to perform various maneuvers and a controlled re-entry through the Earth's atmosphere to an airplane-style landing on a runway, controlled entirely by pre-programmed computer software.

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

    Science.gov (United States)

    Sorteberg, Hilleborg K.

    2010-05-01

    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.

  3. About rats and jackfruit trees: modeling the carrying capacity of a Brazilian Atlantic Forest spiny-rat Trinomys dimidiatus (Günther, 1877 – Rodentia, Echimyidae – population with varying jackfruit tree (Artocarpus heterophyllus L. abundances

    Directory of Open Access Journals (Sweden)

    JHF Mello

    Full Text Available We carried out a six-year study aimed at evaluating if and how a Brazilian Atlantic Forest small mammal community responded to the presence of the invasive exotic species Artocarpus heterophyllus, the jackfruit tree. In the surroundings of Vila Dois Rios, Ilha Grande, RJ, 18 grids were established, 10 where the jackfruit tree was present and eight were it was absent. Previous results indicated that the composition and abundance of this small mammal community were altered by the presence and density of A. heterophyllus. One observed effect was the increased population size of the spiny-rat Trinomys dimidiatus within the grids where the jackfruit trees were present. Therefore we decided to create a mathematical model for this species, based on the Verhulst-Pearl logistic equation. Our objectives were i to calculate the carrying capacity K based on real data of the involved species and the environment; ii propose and evaluate a mathematical model to estimate the population size of T. dimidiatus based on the monthly seed production of jackfruit tree, Artocarpus heterophyllus and iii determinate the minimum jackfruit tree seed production to maintain at least two T. dimidiatus individuals in one study grid. Our results indicated that the predicted values by the model for the carrying capacity K were significantly correlated with real data. The best fit was found considering 20~35% energy transfer efficiency between trophic levels. Within the scope of assumed premises, our model showed itself to be an adequate simulator for Trinomys dimidiatus populations where the invasive jackfruit tree is present.

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

    Science.gov (United States)

    McCoy, Allen H.

    1998-01-01

    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

  5. How honey bees carry pollen

    Science.gov (United States)

    Matherne, Marguerite E.; Anyanwu, Gabriel; Leavey, Jennifer K.; Hu, David L.

    2017-11-01

    Honey bees are the tanker of the skies, carrying thirty percent of their weight in pollen per foraging trip using specialized orifices on their body. How do they manage to hang onto those pesky pollen grains? In this experimental study, we investigate the adhesion force of pollen to the honeybee. To affix pollen to themselves, honey bees form a suspension of pollen in nectar, creating a putty-like pollen basket that is skewered by leg hairs. We use tensile tests to show that the viscous force of the pollen basket is more than ten times the honeybee's flight force. This work may provide inspiration for the design of robotic flying pollinators.

  6. Loren Shriver carries Olympic torch

    Science.gov (United States)

    1996-01-01

    KSC Shuttle Operations Manager Loren J. Shriver proudly displays the Olympic torch that he carried to the top of Launch Pad 39A as his contribution to the July 7, 1996 KSC Olympic torch relay effort. Nineteen other KSC runners also participated in the relay effort at the Center. The Olympic torch arrived at KSC at 1:40 p.m. and traveled a 20-mile course to the pad and then out to the KSC visitor Center. The Space Shuttle Atlantis is behind Shriver, poised for the STS-79 mission, which will feature the fourth docking of the Shuttle with the Russian Mir space station.

  7. Why do dolphins carry sponges?

    Science.gov (United States)

    Mann, Janet; Sargeant, Brooke L; Watson-Capps, Jana J; Gibson, Quincy A; Heithaus, Michael R; Connor, Richard C; Patterson, Eric

    2008-01-01

    Tool use is rare in wild animals, but of widespread interest because of its relationship to animal cognition, social learning and culture. Despite such attention, quantifying the costs and benefits of tool use has been difficult, largely because if tool use occurs, all population members typically exhibit the behavior. In Shark Bay, Australia, only a subset of the bottlenose dolphin population uses marine sponges as tools, providing an opportunity to assess both proximate and ultimate costs and benefits and document patterns of transmission. We compared sponge-carrying (sponger) females to non-sponge-carrying (non-sponger) females and show that spongers were more solitary, spent more time in deep water channel habitats, dived for longer durations, and devoted more time to foraging than non-spongers; and, even with these potential proximate costs, calving success of sponger females was not significantly different from non-spongers. We also show a clear female-bias in the ontogeny of sponging. With a solitary lifestyle, specialization, and high foraging demands, spongers used tools more than any non-human animal. We suggest that the ecological, social, and developmental mechanisms involved likely (1) help explain the high intrapopulation variation in female behaviour, (2) indicate tradeoffs (e.g., time allocation) between ecological and social factors and, (3) constrain the spread of this innovation to primarily vertical transmission.

  8. Why do dolphins carry sponges?

    Directory of Open Access Journals (Sweden)

    Janet Mann

    Full Text Available Tool use is rare in wild animals, but of widespread interest because of its relationship to animal cognition, social learning and culture. Despite such attention, quantifying the costs and benefits of tool use has been difficult, largely because if tool use occurs, all population members typically exhibit the behavior. In Shark Bay, Australia, only a subset of the bottlenose dolphin population uses marine sponges as tools, providing an opportunity to assess both proximate and ultimate costs and benefits and document patterns of transmission. We compared sponge-carrying (sponger females to non-sponge-carrying (non-sponger females and show that spongers were more solitary, spent more time in deep water channel habitats, dived for longer durations, and devoted more time to foraging than non-spongers; and, even with these potential proximate costs, calving success of sponger females was not significantly different from non-spongers. We also show a clear female-bias in the ontogeny of sponging. With a solitary lifestyle, specialization, and high foraging demands, spongers used tools more than any non-human animal. We suggest that the ecological, social, and developmental mechanisms involved likely (1 help explain the high intrapopulation variation in female behaviour, (2 indicate tradeoffs (e.g., time allocation between ecological and social factors and, (3 constrain the spread of this innovation to primarily vertical transmission.

  9. LS-DYNA Analysis of a Full-Scale Helicopter Crash Test

    Science.gov (United States)

    Annett, Martin S.

    2010-01-01

    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.

  10. Exploring Propulsion System Requirements for More and All-Electric Helicopters

    Science.gov (United States)

    Snyder, Christopher A.

    2015-01-01

    Helicopters offer unique capabilities that are important for certain missions. More and all-electric propulsion systems for helicopters offer the potential for improved efficiency, reliability, vehicle and mission capabilities as well as reduced harmful emissions. To achieve these propulsion system-based benefits, the relevant requirements must be understood and developed for the various component, sub-component and ancillary systems of the overall propulsion system. Three representative helicopters were used to explore propulsion and overall vehicle and mission requirements. These vehicles varied from light utility (one to three occupants) to highly capable (three crew members plus ten passengers and cargo). Assuming 15 and 30 year technology availability, analytical models for electric system components were developed to understand component and ancillary requirements. Overall propulsion system characteristics were developed and used for vehicle sizing and mission analyses to understand the tradeoffs of component performance and weight, with increase in vehicle size and mission capability. Study results indicate that only the light utility vehicle retained significant payload for an arbitrary 100 nautical mile range assuming 15 year technology. Thirty year technology assumptions for battery energy storage are sufficient to enable some range and payload capabilities, but further improvements in energy density are required to maintain or exceed payload and range capabilities versus present systems. Hydrocarbon-fueled range extenders can be prudently used to recover range and payload deficiencies resulting from battery energy density limitations. Thermal loads for electric systems are low heat quality, but seem manageable. To realize the benefits from more and all-electric systems, technology goals must be achieved, as well as identify vehicles, missions and systems that are best suited to take advantage of their unique characteristics.

  11. Crash Test of an MD-500 Helicopter with a Deployable Energy Absorber Concept

    Science.gov (United States)

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

    2010-01-01

    On December 2, 2009, a full scale crash test was successfully conducted of a MD-500 helicopter at the NASA Langley Research Center Landing and Impact Research Facility . The purpose of this test was to evaluate a novel composite honeycomb deployable energy absorbing (DEA) concept for attenuation of structural and crew loads during helicopter crashes under realistic crash conditions. The DEA concept is an alternative to external airbags, and absorbs impact energy through crushing. In the test, the helicopter impacted the concrete surface with 11.83 m/s (38.8 ft/s) horizontal, 7.80 m/s (25.6 ft/s) vertical and 0.15 m/s (0.5 ft/s) lateral velocities; corresponding to a resultant velocity of 14.2 m/s (46.5 ft/s). The airframe and skid gear were instrumented with accelerometers and strain gages to determine structural integrity and load attenuation, while the skin of the airframe was covered with targets for use by photogrammetry to record gross vehicle motion before, during, and after the impact. Along with the collection of airframe data, one Hybrid III 50th percentile anthropomorphic test device (ATD), two Hybrid II 50th percentile ATDs and a specialized human surrogate torso model (HSTM) occupant were seated in the airframe and instrumented for the collection of occupant loads. Resultant occupant data showed that by using the DEA, the loads on the Hybrid II and Hybrid III ATDs were in the Low Risk regime for the injury criteria, while structural data showed the airframe retained its structural integrity post crash. Preliminary results show that the DEA is a viable concept for the attenuation of impact loads.

  12. Improved Helicopter Rotor Performance Prediction through Loose and Tight CFD/CSD Coupling

    Science.gov (United States)

    Ickes, Jacob C.

    Helicopters and other Vertical Take-Off or Landing (VTOL) vehicles exhibit an interesting combination of structural dynamic and aerodynamic phenomena which together drive the rotor performance. The combination of factors involved make simulating the rotor a challenging and multidisciplinary effort, and one which is still an active area of interest in the industry because of the money and time it could save during design. Modern tools allow the prediction of rotorcraft physics from first principles. Analysis of the rotor system with this level of accuracy provides the understanding necessary to improve its performance. There has historically been a divide between the comprehensive codes which perform aeroelastic rotor simulations using simplified aerodynamic models, and the very computationally intensive Navier-Stokes Computational Fluid Dynamics (CFD) solvers. As computer resources become more available, efforts have been made to replace the simplified aerodynamics of the comprehensive codes with the more accurate results from a CFD code. The objective of this work is to perform aeroelastic rotorcraft analysis using first-principles simulations for both fluids and structural predictions using tools available at the University of Toledo. Two separate codes are coupled together in both loose coupling (data exchange on a periodic interval) and tight coupling (data exchange each time step) schemes. To allow the coupling to be carried out in a reliable and efficient way, a Fluid-Structure Interaction code was developed which automatically performs primary functions of loose and tight coupling procedures. Flow phenomena such as transonics, dynamic stall, locally reversed flow on a blade, and Blade-Vortex Interaction (BVI) were simulated in this work. Results of the analysis show aerodynamic load improvement due to the inclusion of the CFD-based airloads in the structural dynamics analysis of the Computational Structural Dynamics (CSD) code. Improvements came in the form

  13. Models and impact of patient and public involvement in studies carried out by the Medical Research Council Clinical Trials Unit at University College London: findings from ten case studies.

    Science.gov (United States)

    South, Annabelle; Hanley, Bec; Gafos, Mitzy; Cromarty, Ben; Stephens, Richard; Sturgeon, Kate; Scott, Karen; Cragg, William J; Tweed, Conor D; Teera, Jacqueline; Vale, Claire L

    2016-07-29

    Patient and public involvement (PPI) in studies carried out by the UK Medical Research Council Clinical Trials Unit (MRC CTU) at University College London varies by research type and setting. We developed a series of case studies of PPI to document and share good practice. We used purposive sampling to identify studies representing the scope of research at the MRC CTU and different approaches to PPI. We carried out semi-structured interviews with staff and patient representatives. Interview notes were analysed descriptively to categorise the main aims and motivations for involvement; activities undertaken; their impact on the studies and lessons learned. We conducted 19 interviews about ten case studies, comprising one systematic review, one observational study and 8 randomised controlled trials in HIV and cancer. Studies were either open or completed, with start dates between 2003 and 2011. Interviews took place between March and November 2014 and were updated in summer 2015 where there had been significant developments in the study (i.e. if the study had presented results subsequent to the interview taking place). A wide range of PPI models, including representation on trial committees or management groups, community engagement, one-off task-focused activities, patient research partners and participant involvement had been used. Overall, interviewees felt that PPI had a positive impact, leading to improvements, for example in the research question; study design; communication with potential participants; study recruitment; confidence to carry out or complete a study; interpretation and communication of results; and influence on future research. A range of models of PPI can benefit clinical studies. Researchers should consider different approaches to PPI, based on the desired impact and the people they want to involve. Use of multiple models may increase the potential impacts of PPI in clinical research.

  14. Using Paper Helicopters to Teach Statistical Process Control

    Science.gov (United States)

    Johnson, Danny J.

    2011-01-01

    This hands-on project uses a paper helicopter to teach students how to distinguish between common and special causes of variability when developing and using statistical process control charts. It allows the student to experience a process that is out-of-control due to imprecise or incomplete product design specifications and to discover how the…

  15. Helicopter Gas Turbine Engine Performance Analysis : A Multivariable Approach

    NARCIS (Netherlands)

    Arush, Ilan; Pavel, M.D.

    2017-01-01

    Helicopter performance relies heavily on the available output power of the engine(s) installed. A simplistic single-variable analysis approach is often used within the flight-testing community to reduce raw flight-test data in order to predict the available output power under different atmospheric

  16. At Issue: Helicopter Parents and Millennial Students, an Annotated Bibliography

    Science.gov (United States)

    Pricer, Wayne F.

    2008-01-01

    Technological advances have made it easy for parents and children--many of them students--to communicate instantaneously. Devices and technologies such as cell phones, laptops, texting, and e-mail all enable various forms of instant communication. "Helicopter parents" are regarded as very overprotective and overly involved in the affairs of their…

  17. 77 FR 58925 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-09-25

    ...-17204; AD 2012-19-09] RIN 2120-AA64 Airworthiness Directives; Eurocopter France Helicopters AGENCY... comments. SUMMARY: We are adopting a new airworthiness directive (AD) for Eurocopter France (Eurocopter... contains this AD, the economic evaluation, any comments received, and other information. The street address...

  18. 77 FR 5994 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-02-07

    ...-045-AD; Amendment 39-16936; AD 2012-02-13] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... Eurocopter France EC130B4 helicopters that have not had Eurocopter Modification 073880 incorporated. This AD....m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the economic...

  19. 78 FR 21233 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-04-10

    ...-010-AD; Amendment 39-17409; AD 2013-07-05] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... new airworthiness directive (AD) for Eurocopter France EC130B4 helicopters. This AD requires visually... incorporated-by-reference service information, the economic evaluation, any comments received, and other...

  20. 77 FR 36213 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-06-18

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Eurocopter France...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for Eurocopter France EC130B4 helicopters... holidays. The AD docket contains this proposed AD, the economic evaluation, any comments received, and...

  1. Acoustic Helicopter and FW Aircraft Detection and Classification

    NARCIS (Netherlands)

    Koersel, A.C. van

    2001-01-01

    The possibility to detect the passage of aircraft (either propeller or jet) with one or more mechanical wave sensors (acoustic or seismic) is investigated. An existing algorithm-sensor demonstator can detect and classify helicopter targets. In its current form it is developed to reject other

  2. 78 FR 69989 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-11-22

    ... Airworthiness Directives; Eurocopter France Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for Eurocopter France... France and are approved for operation in the United States. Pursuant to our bilateral agreement with...

  3. 78 FR 65871 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-11-04

    ... Airworthiness Directives; Eurocopter France Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for Eurocopter France... aviation authority of France and are approved for operation in the United States. Pursuant to our bilateral...

  4. 77 FR 70360 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-11-26

    ... helicopters. This AD requires inspecting the cage of the free-wheel assembly for the correct alignment of the... tail rotor drive shaft free-wheel cage, which caused a pilot to experience a heavy jerk in the yaw.... That NPRM proposed to require inspecting the cage of the free-wheel assembly for the correct alignment...

  5. 78 FR 25367 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-05-01

    ... being found on the brackets which appear to be caused by stress corrosion. This condition, if not... We estimate that this AD will affect 733 helicopters of U.S. Registry and that labor rates will average $85 an hour. Inspecting the brackets will take about 4 work-hours per inspection cycle for a labor...

  6. Helicopter Rotor Noise Prediction: Background, Current Status, and Future Direction

    Science.gov (United States)

    Brentner, Kenneth S.

    1997-01-01

    Helicopter noise prediction is increasingly important. The purpose of this viewgraph presentation is to: 1) Put into perspective the recent progress; 2) Outline current prediction capabilities; 3) Forecast direction of future prediction research; 4) Identify rotorcraft noise prediction needs. The presentation includes an historical perspective, a description of governing equations, and the current status of source noise prediction.

  7. 77 FR 39911 - The New York North Shore Helicopter Route

    Science.gov (United States)

    2012-07-06

    ... concern over the danger to irreplaceable historic structures and the noise nuisance caused by the low... Island and thereby reducing helicopter overflights and attendant noise disturbance over nearby... to ``relieve and protect the public health and welfare from aircraft noise,'' the Administrator of...

  8. Flight Test Guide (Part 61 Revised): Instrument Pilot: Helicopter.

    Science.gov (United States)

    Federal Aviation Administration (DOT), Washington, DC. Flight Standards Service.

    The guide provides an outline of the skills required to pass the flight test for an Instrument Pilot Helicopter Rating under Part 61 (revised) of Federal Aviation Regulations. General procedures for flight tests are described and the following pilot operations outlined: maneuvering by reference to instruments, IFR navigation, instrument…

  9. 78 FR 76984 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-12-20

    ... inspecting each jettisonable emergency exit window panel (window) for sealant, and removing any sealant that... prevent failure of the windows to jettison, so helicopter occupants can exit the aircraft during an... Office, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590...

  10. 78 FR 37156 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-06-20

    ... inspecting each jettisonable emergency exit window panel (window) for sealant, and removing any sealant that... prevent failure of the windows to jettison, so helicopter occupants can exit the aircraft during an... comments to the U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor...

  11. 77 FR 57524 - Stage 3 Helicopter Noise Certification Standards

    Science.gov (United States)

    2012-09-18

    ... National Aeronautics and Space Administration (NASA), the FAA, and American helicopter manufacturers set up... the comment (or signing the comment for an association, business, labor union, etc.). DOT's complete... their national regulations to the extent practicable. The United States is a Contracting State to the...

  12. 78 FR 44422 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Science.gov (United States)

    2013-07-24

    ..., AS350C, AS350D, and AS350D1 helicopters with a single hydraulic system and a certain hydraulic pump drive installed. This AD requires inspecting the hydraulic pump drive pulley bearing (pulley bearing) for leaks... failure caused by seizure of the pulley bearing. These actions are intended to prevent hydraulic pump...

  13. Data Input, Processing and Presentation. [helicopter rotor balance measurement

    Science.gov (United States)

    Langer, H. J.

    1984-01-01

    The problems of data acquisition, processing and display are investigated in the case of a helicopter rotor balance. The types of sensors to be employed are discussed in addition to their placement and application in wind tunnel trials. Finally, the equipment for data processing, evaluation and storage are presented with a description of methods.

  14. 78 FR 40954 - Airworthiness Directives; Various Restricted Category Helicopters

    Science.gov (United States)

    2013-07-09

    ... material by hand using an India stone, repeating the MPI inspection, and re- identifying the fitting as..., Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001. Hand Delivery: Deliver to the... helicopters of U.S. registry and that labor costs average $85 per work-hour. Based on these estimates, we...

  15. Neck Pain in Military Helicopter Pilots: Prevalence and Associated Factors

    NARCIS (Netherlands)

    van den Oord, Marieke H. A. H.; de Loose, Veerle; Meeuwsen, Ted; Sluiter, Judith K.; Frings-Dresen, Monique H. W.

    2010-01-01

    Our aim is to estimate the self-reported one-year prevalence of neck pain in military helicopter pilots and to compare work-related, individual, and health-related factors in the pilots with (neck pain group) and without (reference group) regular or continuous neck pain. A questionnaire was

  16. 78 FR 20234 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2013-04-04

    ... prompted by flight crew reports of deviations between the displayed attitude on the attitude display screen... screens occurred simultaneously during flight on several helicopters equipped with the GV76-1 vertical... of the Rotorcraft Flight Manual (RFM) by inserting a copy of this AD into the RFM or by pen and ink...

  17. 77 FR 58971 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Science.gov (United States)

    2012-09-25

    ... prompted by flight crew reports of deviations between the displayed attitude on the attitude display screen... screens occurred simultaneously during flight on several helicopters equipped with the GV76-1 vertical... of the Rotorcraft Flight Manual (RFM) by inserting a copy of this AD into the RFM or by pen and ink...

  18. Engineering team developing helicopter that would investigate nuclear disasters

    OpenAIRE

    Mackay, Steven D.

    2010-01-01

    Students at Virginia Tech's Unmanned Systems Laboratory are perfecting an autonomous helicopter they hope will never be used for its intended purpose. Roughly six feet long and weighing 200 pounds, the re-engineered aircraft is designed to fly into American cities blasted by a nuclear weapon or dirty bomb.

  19. 77 FR 57996 - Airworthiness Directives; Eurocopter France Helicopters

    Science.gov (United States)

    2012-09-19

    ... tangential gearbox (gearbox) and adjusting, as necessary, the fuel shut-off control lever. This AD was prompted by the jamming of one of two fuel shut-off control levers because of solidified grease in the... control levers to shut off fuel going into the engine and to shut off the helicopter's electrical power...

  20. Tone-corrected metrics for pre-2005 INM helicopters

    Science.gov (United States)

    2012-07-01

    Of the 21 Helicopters represented in INM 7.0b, only five include the tone-corrected metrics. The calculation of these metrics involves the analysis of 1/3 octave-band data obtained during the source data measurement process, and requires sound-pressu...

  1. A theoretical analysis of the electromagnetic environment of the AS330 super Puma helicopter external and internal coupling

    Science.gov (United States)

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

    1991-01-01

    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.

  2. Vibration Suppression of a Helicopter Fuselage by Pendulum Absorbers : Rigid-Body Blades with Aerodynamic Excitation Force

    Science.gov (United States)

    Nagasaka, Imao; Ishida, Yukio; Koyama, Takayuki; Fujimatsu, Naoki

    Currently, some kinds of helicopters use pendulum absorbers in order to reduce vibrations. Present pendulum absorbers are designed based on the antiresonance concept used in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics. Therefore, the best suppression cannot be attained by using the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. Our previous study proposed a 2-degree-of-freedom (2DOF) model composed of a rotor blade and a pendulum absorber. The blade was considered as a rigid body and it was excited by giving a sinusoidal deflection at its end. The present paper proposes a 3DOF model that is more similar to the real helicopter, since the freedom of the fuselage is added and the periodic forces are applied to the blade by aerodynamic force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is obtained when the natural frequency of the pendulum is a little bit different from the frequency of the external force. Various unique nonlinear characteristics, such as bifurcations, are also shown.

  3. Neural network disturbance observer-based distributed finite-time formation tracking control for multiple unmanned helicopters.

    Science.gov (United States)

    Wang, Dandan; Zong, Qun; Tian, Bailing; Shao, Shikai; Zhang, Xiuyun; Zhao, Xinyi

    2018-02-01

    The distributed finite-time formation tracking control problem for multiple unmanned helicopters is investigated in this paper. The control object is to maintain the positions of follower helicopters in formation with external interferences. The helicopter model is divided into a second order outer-loop subsystem and a second order inner-loop subsystem based on multiple-time scale features. Using radial basis function neural network (RBFNN) technique, we first propose a novel finite-time multivariable neural network disturbance observer (FMNNDO) to estimate the external disturbance and model uncertainty, where the neural network (NN) approximation errors can be dynamically compensated by adaptive law. Next, based on FMNNDO, a distributed finite-time formation tracking controller and a finite-time attitude tracking controller are designed using the nonsingular fast terminal sliding mode (NFTSM) method. In order to estimate the second derivative of the virtual desired attitude signal, a novel finite-time sliding mode integral filter is designed. Finally, Lyapunov analysis and multiple-time scale principle ensure the realization of control goal in finite-time. The effectiveness of the proposed FMNNDO and controllers are then verified by numerical simulations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  4. Linear modeling of rotorcraft for stability analysis and preliminary design

    OpenAIRE

    Wirth, Walter M.

    1993-01-01

    Approved for public release; distribution is unlimited. This thesis investigates linear state space modeling of single main rotor helicopters culminating in a computer program that can be used for 1) stability and control analysis for any single main rotor helicopter or 2) preliminary design of a helicopter. The trim solution for a flight condition is found, the aircraft is perturbed about the nominal point, and the stability and control derivatives are determined. State space models and ...

  5. Identification of stability and control derivatives for AS 355 L2 helicopter with Quad-M/CTA methodology

    Science.gov (United States)

    de Oliveira, Sérgio Servilha; Menegaldo, Luciano Luporini

    2012-11-01

    This work presents results obtained from a study of case for H-55 Helicopter System Identification which was carried out by an implementation of Quad-M Methodology purposed for Jategaonkar. The implementation performed was based on Cruz et al whose works were developed in Centro Técnico Aeroespacial (CTA). A comparison between Stability and Control Derivatives tables from these results and those from literature is performed for some important flight conditions. This comparison allows us to conclude about the reliability of the method, to present preliminary SCD tables for the studied aircraft and point to possible future works.

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

    DEFF Research Database (Denmark)

    Tølbøll, R.J.; Christensen, N.B.

    2006-01-01

    but can resolve layer boundary to a depth of more than 100 m. Modeling experiments also show that the effect of altimeter errors on the inversion results is serious. We suggest a new interpretation scheme for HEM data founded solely on full nonlinear 1D inversion and providing layered-earth models...... 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...... supported by datamisfit parameters and a quantitative model-parameter analysis. The backbone of the scheme is the removal of cultural coupling effects followed by a multilayer inversion that in turn provides reliable starting models for a subsequent few-layer inversion. A new procedure for correlation...

  7. Proposed health state awareness of helicopter blades using an artificial neural network strategy

    Science.gov (United States)

    Lee, Andrew; Habtour, Ed; Gadsden, S. A.

    2016-05-01

    Structural health prognostics and diagnosis strategies can be classified as either model or signal-based. Artificial neural network strategies are popular signal-based techniques. This paper proposes the use of helicopter blades in order to study the sensitivity of an artificial neural network to structural fatigue. The experimental setup consists of a scale aluminum helicopter blade exposed to transverse vibratory excitation at the hub using single axis electrodynamic shaker. The intent of this study is to optimize an algorithm for processing high-dimensional data while retaining important information content in an effort to select input features and weights, as well as health parameters, for training a neural network. Data from accelerometers and piezoelectric transducers is collected from a known system designated as healthy. Structural damage will be introduced to different blades, which they will be designated as unhealthy. A variety of different tests will be performed to track the evolution and severity of the damage. A number of damage detection and diagnosis strategies will be implemented. A preliminary experiment was performed on aluminum cantilever beams providing a simpler model for implementation and proof of concept. Future work will look at utilizing the detection information as part of a hierarchical control system in order to mitigate structural damage and fatigue. The proposed approach may eliminate massive data storage on board of an aircraft through retaining relevant information only. The control system can then employ the relevant information to intelligently reconfigure adaptive maneuvers to avoid harmful regimes, thus, extending the life of the aircraft.

  8. Novel controller design demonstration for vibration alleviation of helicopter rotor blades

    Science.gov (United States)

    Ulker, Fatma Demet; Nitzsche, Fred

    2012-04-01

    This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor sys- tems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-delity aeroelastic simulations. To validate the con- troller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations.

  9. Helicopter collision avoidance and brown-out recovery with HELLAS

    Science.gov (United States)

    Seidel, Christian; Schwartz, Ingo; Kielhorn, Peter

    2008-10-01

    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.

  10. Novelties that change carrying capacity.

    Science.gov (United States)

    Erwin, Douglas H

    2012-09-01

    Comparative developmental studies have revealed a rich array of details about the patterns and processes of morphological change in animals and increasingly in plants. But, applying these insights to the study of major episodes of evolutionary innovation requires understanding how these novel morphologies become established and sufficiently abundant (either as individuals within a species or as a clade of species) to be preserved in the fossil record, and, in many cases, to influence ecological processes. Evolutionary novelties may: (1) disappear without changing the species; (2) be associated with the generation (through selection or drift) of a new species; and if the latter (3) may or may not become ecologically significant. Only the latter are commonly preserved in the fossil record. These alternatives mirror the distinction among historians of technology between innovation and invention. Here, I argue that specific sorts of evolutionary inventions drive ecological transformation, essentially constructing an environment for themselves and ancillary organisms through ecological spillover effects, increasing the "carrying capacity" of an ecosystem. Copyright © 2011 Wiley Periodicals, Inc.

  11. Integrated interpretation of helicopter and ground-based geophysical data recorded within the Okavango Delta, Botswana

    DEFF Research Database (Denmark)

    Podgorski, Joel E.; Green, Alan G.; Kalscheuer, Thomas

    2015-01-01

    ) data recorded across most of the delta, (ii) 2D models and images derived from ground-based electrical resistance tomographic, transient electromagnetic, and high resolution seismic reflection/refraction tomographic data acquired at four selected sites in western and north-central regions of the delta...... on the arcuate nature of its front and the semi-conical shape of its upper surface in the HTEM resistivity model. Moderate to high resistivity subhorizontal layers are consistent with this interpretation. The deepest unit is the basement with very high resistivity, high P-wave velocity, and low or complex......Integration of information from the following sources has been used to produce a much better constrained and more complete four-unit geological/hydrological model of the Okavango Delta than previously available: (i) a 3D resistivity model determined from helicopter time-domain electromagnetic (HTEM...

  12. 75 FR 69862 - Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

    Science.gov (United States)

    2010-11-16

    ... AD was prompted by two reports of cracks detected in the hub in the area near the flex beam bolt hole... of the 5 flex beam bolt hole locations. If you found a crack, the Emergency AD 2010-18-51 required... of the 5 flex beam bolt hole locations. If you find a crack, this AD requires, before further flight...

  13. 76 FR 41662 - Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

    Science.gov (United States)

    2011-07-15

    ...-18-51. That EAD was prompted by two reports of cracks detected in the lower hub near the flex beam... rotor lower hub assembly (lower hub) for a crack, and if you find a crack, before further flight... cracked lower hub, the existing AD requires reporting the finding to the Los Angeles Aircraft...

  14. 75 FR 12441 - Airworthiness Directives; MD Helicopters, Inc. Model MD-900 Helicopters

    Science.gov (United States)

    2010-03-16

    ..., and to retain the life limits of various other parts. Interested persons have been afforded an... the States, or on the distribution of power and responsibilities among the various levels of...) 900C2010192-105, -107, -109, or -111, on or before 1,800 hours time- in-service (TIS). (2) The collective...

  15. The Apache Longbow-Hellfire Missile Test at Yuma Proving Ground: Ecological Risk Assessment for Helicopter Overflight

    Energy Technology Data Exchange (ETDEWEB)

    Efroymson, Rebecca Ann [ORNL; Hargrove, William Walter [ORNL; Suter, Glenn [U.S. Environmental Protection Agency

    2008-01-01

    A multi-stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus of the assessment was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, M60-A1 tanks. This paper focuses on the wildlife risk assessment for the helicopter overflight. The primary stressors were sound and the view of the aircraft. Exposure to desert mule deer (Odocoileus hemionus crooki) was quantified using Air Force sound contour programs NOISEMAP and MR_NMAP, which gave very different results. Slant distance from helicopters to deer was also used as a measure of exposure that integrated risk from sound and view of the aircraft. Exposure-response models for the characterization of effects consisted of behavioral thresholds in sound exposure level or maximum sound level units or slant distance. Available sound thresholds were limited for desert mule deer, but a distribution of slant-distance thresholds was available for ungulates. The risk characterization used a weight-of-evidence approach and concluded that risk to mule deer behavior from the Apache overflight is uncertain, but that no risk to mule deer abundance and reproduction is expected.

  16. 3D Digitisation of Large-Scale Unstructured Great Wall Heritage Sites by a Small Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Fucheng Deng

    2017-04-01

    Full Text Available The ancient Great Wall of China has long suffered from damage due to natural factors and human activities. A small low-cost unmanned helicopter system with a laser scanner and a digital camera is developed to efficiently visualize the status of the huge Great Wall area. The goal of the system is to achieve 3D digitisation of the large-scale Great Wall using a combination of fly-hover-scan and flying-scan modes. However, pose uncertainties of the unmanned helicopter could cause mismatching among point clouds acquired by each hovering-scan. This problem would become more severe as the target area becomes larger and more unstructured. Therefore, a hierarchical optimization framework is proposed in this paper to achieve 3D digitisation of the large-scale unstructured Great Wall with unpredictable pose uncertainties of the unmanned helicopter. In this framework, different optimization methodologies are proposed for the fly-hover-scan and flying-scan modes, respectively, because different scan modes would result in different features of point clouds. Moreover, a user-friendly interface based on WebGL has been developed for 3D model visualization and comparison. Experimental results demonstrate the feasibility of the proposed framework for 3D digitisation of the Great Wall segments.

  17. Surveying glacier bedrock topography with a helicopter-borne dual-polarization ground-penetrating radar system

    Science.gov (United States)

    Langhammer, L.; Rabenstein, L.; Schmid, L.; Bauder, A.; Schaer, P.; Maurer, H.

    2017-12-01

    Glacier mass estimations are crucial for future run-off projections in the Swiss Alps. Traditionally, ice thickness modeling approaches and ground-based radar transects have been the tools of choice for estimating glacier volume in high mountain areas, but these methods either contain high uncertainties or are logistically expensive and offer mostly only sparse subsurface information. We have developed a helicopter-borne dual-polarization ground-penetrating radar (GPR) system, which enhances operational feasibility in rough, high-elevation terrain and increases the data output per acquisition campaign significantly. Our system employs a prototype pulseEKKO device with two broadside 25-MHz antenna pairs fixed to a helicopter-towed wooden frame. Additionally attached to the system are a laser altimeter for measuring the flight height above ground, three GPS receivers for accurate positioning and a GoPro camera for obtaining visual images of the surface. Previous investigations have shown the significant impact of the antenna dipole orientation on the detectability of the bedrock reflection. For optimal results, the dipoles of the GPR should be aligned parallel to the strike direction of the surrounding mountain walls. In areas with a generally unknown bedrock topography, such as saddle areas or diverging zones, a dual-polarization system is particularly useful. This could be demonstrated with helicopter-borne GPR profiles acquired on more than 25 glaciers in the Swiss Alps. We observed significant differences in ice-bedrock interface visibility depending on the orientation of the antennas.

  18. Examining the Resilience of Crop Production, Livestock Carrying Capacity, and Woodland Density in a Rural Zimbabwean Socio-Ecological System Using Agent-Based Models Representing Human Management Decisions

    Science.gov (United States)

    Eitzel Solera, M. V.; Neves, K.; Veski, A.; Solera, J.; Omoju, O. E.; Mawere Ndlovu, A.; Wilson, K.

    2016-12-01

    As climate change increases the pressures on arid ecosystems by changing timing and amount of rainfall, understanding the ways in which human management choices affect the resilience of these systems becomes key to their sustainability. On marginal farmland in Mazvihwa, Midlands Province, the historical carrying capacity of livestock has been consistently surprisingly high. We explore this phenomenon by building an agent-based model in NetLogo from a wealth of long-term data generated by the community-based participatory research team of The Muonde Trust, a Zimbabwean non-governmental organization. We combine the accumulated results of 35 years of indigenous and local knowledge with national datasets such as rainfall records. What factors keep the carrying capacity high? What management choices can maintain crops, livestock, and woodland at levels necessary for the community's survival? How do these choices affect long-term sustainability, and does increasing resilience at one scale reduce resilience at another scale? We use our agent-based model to explore the feedbacks between crops, livestock, and woodland and the impacts of various human choices as well as temporal and spatial ecological variation. By testing different scenarios, we disentangle the complex interactions between these components. We find that some factors out of the community's control can strongly affect the sustainability of the system through times of drought, and that supplementary feed may maintain livestock potentially at the expense of other resources. The challenges to resilience encountered by the farmers in Mazvihwa are not unique - many indigenous and rural people face drought and the legacies of colonialism, which contribute to lowered resilience to external challenges such as climate change, epidemics, and political instability. Using the agent-based model as a tool for synthesis and exploration initiates discussion about resilience-enhancing management choices for Mazvihwa's farmer-researchers.

  19. Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.

    Science.gov (United States)

    Yang, Xianfeng; Zhang, Zhiqiang; Yang, Jialing; Sun, Yuxin

    2016-01-01

    The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.

  20. Do Salmonella carry spare tyres?

    Science.gov (United States)

    McQuiston, John R; Fields, Patricia I; Tauxe, Robert V; Logsdon, John M

    2008-04-01

    Salmonellae are enterobacteria that have the unique ability to change their flagellar composition by switching expression among two loci that encode the major flagellin protein. This property is not available to all Salmonella, but is species, subspecies and serotype specific. Curiously, the subsequent loss of the second locus in some lineages of Salmonella has apparently been tolerated and, indeed, has led to considerable success for some lineages. We discuss here an evolutionary model for maintenance of this unique function and the possible evolutionary advantages of loss or preservation of this mechanism. We hypothesize that the second flagellin locus is a genetic 'spare tyre' used in particular environmental circumstances.

  1. Quadrotor helicopter for surface hydrological measurements

    Science.gov (United States)

    Pagano, C.; Tauro, F.; Porfiri, M.; Grimaldi, S.

    2013-12-01

    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

  2. Simulation and control of a helicopter operating in a ship airwake

    Science.gov (United States)

    Lee, Dooyong

    This thesis describes a study in simulation and control of a helicopter operating in proximity to a ship. The helicopter/ship combination used in the study is a UH-60A helicopter operating off an LHA class ship. This represents the same aircraft ship combination used in the JSHIP program. The flight dynamics model is based on the GENHEL software and this flight dynamics model has been updated to include high-order dynamic inflow model and gust penetration effects of the ship airwake. To simulate the pilot control inputs for typical shipboard operations, an optimal control model of the human pilot is developed. The pilot model can be tuned to achieve different tracking performances based on a desired crossover frequency in each control axis and is designed to operate over a range of airspeeds using a simple gain scheduling algorithm. The pilot model is then used to predict pilot workload for shipboard operations in two different wind-over-deck conditions. Validation studies are conducted using both time and frequency domain analyses to understand the impact of a time-varying ship airwake on the pilot control activity for the approach and departure operations. The pilot control input autospectra predicted from the simulation model are compared to those of flight test data from the JSHIP program. It is found that the control activities are similar in low frequency range but underestimate in magnitude in the high frequency range (over 1.5 Hz). There is clear evidence that the human pilot is continually moving cyclic stick in the maneuver. At this stage of the study no attempt has been made to optimize the parameters of the human pilot model. The paper also discusses the application of a stochastic airwake model for more efficient simulation. This new airwake model is derived from the simulation with the full CFD airwake by extracting an equivalent six-dimensional gust vector. The spectral properties of the gust components are then analyzed, and shaping filters are

  3. Multivariable Super Twisting Based Robust Trajectory Tracking Control for Small Unmanned Helicopter

    Directory of Open Access Journals (Sweden)

    Xing Fang

    2015-01-01

    Full Text Available This paper presents a highly robust trajectory tracking controller for small unmanned helicopter with model uncertainties and external disturbances. First, a simplified dynamic model is developed, where the model uncertainties and external disturbances are treated as compounded disturbances. Then the system is divided into three interconnected subsystems: altitude subsystem, yaw subsystem, and horizontal subsystem. Second, a disturbance observer based controller (DOBC is designed based upon backstepping and multivariable super twisting control algorithm to obtain robust trajectory tracking property. A sliding mode observer works as an estimator of the compounded disturbances. In order to lessen calculative burden, a first-order exact differentiator is employed to estimate the time derivative of the virtual control. Moreover, proof of the stability of the closed-loop system based on Lyapunov method is given. Finally, simulation results are presented to illustrate the effectiveness and robustness of the proposed flight control scheme.

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

    DEFF Research Database (Denmark)

    Tølbøll, R.J.; Christensen, N.B.

    2006-01-01

    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...... but can resolve layer boundary to a depth of more than 100 m. Modeling experiments also show that the effect of altimeter errors on the inversion results is serious. We suggest a new interpretation scheme for HEM data founded solely on full nonlinear 1D inversion and providing layered-earth models...

  5. Design and Testing of Flight Control Laws on the RASCAL Research Helicopter

    Science.gov (United States)

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

    2001-01-01

    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.

  6. Optimal control of helicopters following power failure. Helicopter no engine koshoji no saiteki hiko seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, Y.

    1993-01-01

    In order to study the optimal control of helicopters, the control procedures following power failure were theoretically investigated by applying nonlinear optimal control theory to the following four optimization problems. The first was minimization of the touchdown speed following power failure. Comparisons between the calculated optimal solutions and the empirical flight test results showed that pilots used nonoptimal controls, especially in the timing and amplitude of the collective flare before touchdowns. The second was prediction of the height-velocity (H-V) boundaries. The calculated H-V boundaries showed good correlation with the flight test results. The third was optimization of the takeoff procedures for category A STOL operation following power failure. The results showed that the required takeoff distance using the normal takeoff procedure can be significantly reduced. The fourth was evaluation of the takeoff performance for category A VTOL operation. The calculating method of the maximum takeoff weight was confirmed, and possibility of allowing the payload to be increased was shown. 38 refs., 53 figs.

  7. BOREAS RSS-03 Atmospheric Conditions from a Helicopter-Mounted Sunphotometer

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains Helicopter-based measurements of atmospheric conditions acquired during the BOReal Ecosystem-Atmosphere Study (BOREAS) processed to estimates of aerosol...

  8. BOREAS RSS-03 Atmospheric Conditions from a Helicopter-Mounted Sunphotometer

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Contains Helicopter-based measurements of atmospheric conditions acquired during the BOReal Ecosystem-Atmosphere Study (BOREAS) processed to estimates of...

  9. A method for determining internal noise criteria based on practical speech communication applied to helicopters

    Science.gov (United States)

    Sternfeld, H., Jr.; Doyle, L. B.

    1978-01-01

    The relationship between the internal noise environment of helicopters and the ability of personnel to understand commands and instructions was studied. A test program was conducted to relate speech intelligibility to a standard measurement called Articulation Index. An acoustical simulator was used to provide noise environments typical of Army helicopters. Speech material (command sentences and phonetically balanced word lists) were presented at several voice levels in each helicopter environment. Recommended helicopter internal noise criteria, based on speech communication, were derived and the effectiveness of hearing protection devices were evaluated.

  10. A new approach to helicopter rotor blade research instrumentation

    Science.gov (United States)

    Knight, V. H., Jr.

    1978-01-01

    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.

  11. Helicopter Acoustic Flight Test with Altitude Variation and Maneuvers

    Science.gov (United States)

    Watts, Michael E.; Greenwood, Eric; Sim, Ben; Stephenson, James; Smith, Charles D.

    2016-01-01

    A cooperative flight test campaign between NASA and the U.S. Army was performed from September 2014 to February 2015. The purposes of the testing were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. This test was performed at three test sites (0, 4000, and 7000 feet above mean sea level) with two aircraft (AS350 SD1 and EH-60L) tested at each site. This report provides an overview of the test, documents the data acquired and describes the formats of the stored data.

  12. NASA/FAA experiments concerning helicopter IFR airworthiness criteria

    Science.gov (United States)

    Lebacqz, J. V.

    1983-01-01

    A sequence of ground and flight simulation experiments was conducted as part of a joint NASA/FAA program to investigate helicopter instrument flight rules (IFR) airworthiness criteria. The first six of these experiments are described and the results summarized. Five of the experiments were conducted on large amplitude motion base simulators; V/STOLAND UH-1H variable stability helicopter was used in the flight experiment. Airworthiness implications of selected variables that were investigated across all of the experiments are discussed, including the level of longitudinal static stability, the type of stability and control augmentation, the addition of flight director displays, and the type of instrument approach task. Among the specific results reviewed are the adequacy of neutral longitudinal statics for dual pilot approaches and the requirement for pitch and roll attitude stabilization in the stability and control augmentation system to achieve flying qualities evaluated as satisfactory.

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

    Directory of Open Access Journals (Sweden)

    Huiliao Yang

    2014-01-01

    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.

  14. Engineering Design Handbook. Helicopter Engineering. Part One. Preliminary Design

    Science.gov (United States)

    1974-08-30

    tember 1966. REFERENCES 17. E. S. Quade, System Analysis Techniques for Planning-Programming-Budgeting, P-3063, I. C. W. Churchman , R. L. Ackoff, and E...February 1970. 1966. 78. Gessow & Myers, op. cit., p. 117 ff. 70. Douglass J. Wilde and Charles S. Beightler, 79. P. R. Payne, Helicopter Dynamics and...July 1958). Symposium on Shock and Vibration, Key 43. B. B. Blake, J. E. Burkam, and R. G. Loewy, West , Florida. November 1971. "Recent Studies of

  15. Conservative Management of Mechanical Neck Pain in a Helicopter Pilot.

    Science.gov (United States)

    Alagha, Babak

    2015-10-01

    Acute and chronic spinal symptoms such as neck pain may limit flying performance significantly and disqualify the pilot from flight duty. Mechanical neck pain is very common among pilots because of their exposure to vibration, +GZ forces, helmet weight, poor neck posture during air combat maneuvers, previous neck injuries, and poor treatment plans for such injuries. Successful treatment of such injuries requires appropriate therapeutic procedures as well as an aeromedical assessment. The aim of this case study was to demonstrate the benefits of conservative procedures such as spinal manipulation and mobilization therapy (SMMT) and exercise therapy (ET) in treating chronic mechanical neck pain in an Iranian commercial helicopter pilot. A 36-yr-old male patient presented to the clinic with moderate, intermittent nonradicular chronic neck pain and limited range of motion over a 2-yr period. The patient was treated with cervical and upper thoracic SMMT followed by home ET for 5 wk. After this period, the patient reported significant recovery and improvement in range of motion in his neck. Mechanical neck pain is very common among helicopter pilots. Although Air Force and Navy waiver guides recommend nonsteroidal anti-inflammatory medications as well as SMMT and ET, there are currently very few published studies that examine the benefits of manual and exercise therapy for treating mechanical neck pain in commercial and military pilots. Based on the results of this study, it seems that SMMT and ET may be a safe and effective in treatment of uncomplicated mechanical neck pain in helicopter pilots. Alagha B. Conservative management of mechanical neck pain in a helicopter pilot.

  16. Aerodynamic Design Optimisation for Utility Helicopter Drag Reduction

    OpenAIRE

    Grawunder, Moritz

    2017-01-01

    In order to reduce helicopter’s fuel flow requirements and emissions, the aerodynamic design of Twin-Engine-Light (TEL) class utility helicopter is revised. A viable approach for achieving efficiency gains is reducing the helicopter’s parasite drag. This is achieved by the development of aerodynamic fairings for the skid-landing-gear and passive flow control devices at the rear fuselage. On aggregate, a parasite drag benefit of 22% is achieved, which corresponds to about 10% fuel flow reducti...

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

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej

    2015-12-01

    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.

  18. Advanced automatic target recognition for police helicopter missions

    Science.gov (United States)

    Stahl, Christoph; Schoppmann, Paul

    2000-08-01

    The results of a case study about the application of an advanced method for automatic target recognition to infrared imagery taken from police helicopter missions are presented. The method consists of the following steps: preprocessing, classification, fusion, postprocessing and tracking, and combines the three paradigms image pyramids, neural networks and bayesian nets. The technology has been developed using a variety of different scenes typical for military aircraft missions. Infrared cameras have been in use for several years at the Bavarian police helicopter forces and are highly valuable for night missions. Several object classes like 'persons' or 'vehicles' are tested and the possible discrimination between persons and animals is shown. The analysis of complex scenes with hidden objects and clutter shows the potentials and limitations of automatic target recognition for real-world tasks. Several display concepts illustrate the achievable improvement of the situation awareness. The similarities and differences between various mission types concerning object variability, time constraints, consequences of false alarms, etc. are discussed. Typical police actions like searching for missing persons or runaway criminals illustrate the advantages of automatic target recognition. The results demonstrate the possible operational benefits for the helicopter crew. Future work will include performance evaluation issues and a system integration concept for the target platform.

  19. Measurement and Characterization of Helicopter Noise at Different Altitudes

    Science.gov (United States)

    Watts, Michael E.; Greenwood, Eric; Stephenson, James

    2016-01-01

    This paper presents an overview of a flight test campaign performed at different test sites whose altitudes ranged from 0 to 7000 feet above mean sea level (AMSL) between September 2014 and February 2015. The purposes of this campaign were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. In addition to describing the test campaign, results of the acoustic effects of altitude variation for the AS350 SD1 and EH-60L aircraft are presented. Large changes in acoustic amplitudes were observed in response to changes in ambient conditions when the helicopter was flown at constant indicated airspeed and gross weight at the three test sites. However, acoustic amplitudes were found to scale with ambient pressure when flight conditions were defined in terms of the non-dimensional parameters, such as the weight coefficient and effective hover tip Mach number.

  20. Two-Dimensional Fourier Transform Analysis of Helicopter Flyover Noise

    Science.gov (United States)

    SantaMaria, Odilyn L.; Farassat, F.; Morris, Philip J.

    1999-01-01

    A method to separate main rotor and tail rotor noise from a helicopter in flight is explored. Being the sum of two periodic signals of disproportionate, or incommensurate frequencies, helicopter noise is neither periodic nor stationary. The single Fourier transform divides signal energy into frequency bins of equal size. Incommensurate frequencies are therefore not adequately represented by any one chosen data block size. A two-dimensional Fourier analysis method is used to separate main rotor and tail rotor noise. The two-dimensional spectral analysis method is first applied to simulated signals. This initial analysis gives an idea of the characteristics of the two-dimensional autocorrelations and spectra. Data from a helicopter flight test is analyzed in two dimensions. The test aircraft are a Boeing MD902 Explorer (no tail rotor) and a Sikorsky S-76 (4-bladed tail rotor). The results show that the main rotor and tail rotor signals can indeed be separated in the two-dimensional Fourier transform spectrum. The separation occurs along the diagonals associated with the frequencies of interest. These diagonals are individual spectra containing only information related to one particular frequency.

  1. Modelagem de redes logísticas com custos de inventário calculados a partir da cobertura de estoque Logistic networks modeling with inventory carrying costs calculated using inventory turnover

    Directory of Open Access Journals (Sweden)

    Ricardo Hamad

    2011-01-01

    Full Text Available A consideração dos custos de inventário tem se tornado cada vez mais importante na análise dos trade-offs e na tomada de decisões sobre redes logísticas. O artigo propõe uma metodologia para tratamento do custo de inventário a partir da cobertura de estoque esperada em cada instalação, incorporada na modelagem matemática da localização de fábricas e/ou centros de distribuição em redes logísticas com vários elos, representando uma nova versão do modelo apresentado em Hamad e Gualda (2008. As principais contribuições desta metodologia em relação a outros métodos encontrados na literatura são a facilidade de aplicação do método, a inclusão de restrições ligadas à capacidade de armazenagem e a consideração do custo total de inventário, e não apenas do custo relacionado aos produtos modelados.Inventory carrying cost has become very important in the analysis of the trade-offs and an important component to be considered when taking decisions about a logistic network. This paper proposes a methodology incorporated in a multi-echelon sourcing decision model, to be considered as a new version of the model presented in Hamad, Gualda (2008. It treats the carrying costs using the inventory Days-on-hand estimate in each echelon of the chain (plants and/or Distribution Centers. The main contributions of this methodology compared to other options found in the literature are the simplicity of its application, the consideration of all inventory costs (not only the ones related to the products being modeled and, also, the inclusion of constraints related to warehousing capacity.

  2. Optimizing HF antenna systems on the Dolphin and Sea Hawk helicopters

    Science.gov (United States)

    Crawford, James B.

    1987-09-01

    Making an aircraft available and modifying it to test various antenna systems and configurations is extremely costly. The computer model is an excellent alternative means of analyzing antenna systems for optimum communication system performance. In this study electromagnetic wire grid computer models of two helicopters and eight HF antenna configurations are developed using Interactive Graphics Utility for Automated NEC Analysis (IGUANA). Numerical Electromagnetics Code (NEC) is used to obtain radiation patterns, and the Advanced Prophet program is used to develop the criteria for judging system effectiveness. These computer results compare favorably with test range data, showing great savings of cost. They provide the additional advantage of showing radiation patterns at an elevated angle for sky wave propagation analysis (patterns which cannot be obtained on an antenna test range).

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

    Science.gov (United States)

    Venkatesan, C.; Friedmann, P. P.

    1984-01-01

    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. The Effects of Modafinil on Aviator Performance During 40 Hours of Continuous Wakefulness: A UH-60 Helicopter Simulator Study

    National Research Council Canada - National Science Library

    Caidwell, John

    1999-01-01

    ...) activation in helicopter pilots who had been deprived of sleep. Six Army helicopter pilots were each exposed to two 40-hour periods of continuous wakefulness separated by one night of recovery sleep...

  5. Development of a snubber type magnetorheological fluid elastomeric lag damper for helicopter stability augmentation

    Science.gov (United States)

    Ngatu, Grum T.

    Most advanced helicopter rotors are typically fitted with lag dampers, such as elastomeric or hybrid fluid-elastomeric (FE) lag dampers, which have lower parts counts, are lighter in weight, easier to maintain, and more reliable than conventional hydraulic dampers. However, the damping and stiffness properties of elastomeric and fluid elastomeric lag dampers are non-linear functions of lag/rev frequency, dynamic lag amplitude, and operating temperature. It has been shown that elastomeric damping and stiffness levels diminish markedly as amplitude of damper motion increases. Further, passive dampers tend to present severe damping losses as damper operating temperature increases either due to in-service self-heating or hot atmospheric conditions. Magnetorheological (MR) dampers have also been considered for application to helicopter rotor lag dampers to mitigate amplitude and frequency dependent damping behaviors. MR dampers present a controllable damping with little or no stiffness. Conventional MR dampers are similar in configuration to linear stroke hydraulic type dampers, which are heavier, occupy a larger space envelope, and are unidirectional. Hydraulic type dampers require dynamic seal to prevent leakage, and consequently, frequent inspections and maintenance are necessary to ensure the reliability of these dampers. Thus, to evaluate the potential of combining the simplicity and reliability of FE and smart MR technologies in augmenting helicopter lag mode stability, an adaptive magnetorheological fluid-elastomeric (MRFE) lag damper is developed in this thesis as a retrofit to an actual fluid-elastomeric (FE) lag damper. Consistent with the loading condition of a helicopter rotor system, single frequency (lag/rev) and dual frequency (lag/rev at 1/rev) sinusoidal loading were applied to the MRFE damper at varying temperature conditions. The complex modulus method was employed to linearly characterize and compare the performance of the MRFE damper with the

  6. A helicopter that flaps its wings : The Ornicopter flaps its wings like a bird to get into the air

    NARCIS (Netherlands)

    Van Holten, T.; Mols, B.

    2003-01-01

    No other type of aircraft is as manoeuvrable as a helicopter. Reverse in full flight, rotate in the air, hover at a standstill, the helicopter can do it all. The police, fire services, medical services, military and civil aviation all use the helicopter for the freedom of flight it offers. However,

  7. Should women carry their antenatal records?

    OpenAIRE

    Draper, J; Field, S; Thomas, H; Hare, M J

    1986-01-01

    A study of women's views on carrying their medical records during their pregnancy was conducted in Cambridge in 1982. Eighty eight women who were given their full records were compared with a control group of 83 women who carried the traditional cooperation card, both groups answering postal questionnaires about the advantages and disadvantages of carrying their respective records. Most women found advantages in carrying the complete record, although it was too large to carry for practical pu...

  8. Improvement of helicopter attitude stability by active control of the conventional swash plate

    Science.gov (United States)

    Ham, Norman D.

    1993-01-01

    The Final Report on improvement of helicopter attitude stability by active control of the conventional swash plate covering the period from Nov. 1986 to Dec. 1993 is presented. A paper on the history, principles, and applications of helicopter individual-blade-control is included.

  9. 14 CFR Appendix B to Part 29 - Airworthiness Criteria for Helicopter Instrument Flight

    Science.gov (United States)

    2010-01-01

    .... Static longitudinal stability. (a) General. The helicopter must possess positive static longitudinal control force stability at critical combinations of weight and center of gravity at the conditions... and landing; (iii) For Category A helicopters, the dynamic stability requirements of Subpart B must...

  10. 14 CFR Appendix B to Part 27 - Airworthiness Criteria for Helicopter Instrument Flight

    Science.gov (United States)

    2010-01-01

    ... longitudinal stability. (a) General. The helicopter must possess positive static longitudinal control force.... Stability must be shown throughout the speed range 20 knots either side of trim with— (i) The helicopter... speed, there must be no negative dihedral stability perceptible to the pilot through lateral control...

  11. 78 FR 44039 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-07-23

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: We propose to adopt a new airworthiness directive (AD) for Eurocopter Deutschland... airworthiness directive (AD): Eurocopter Deutschland GmbH Helicopters (Eurocopter): Docket No. FAA-2013-0642...

  12. 78 FR 22209 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-04-15

    ... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: We propose to adopt a new airworthiness directive (AD) for Eurocopter Deutschland...): Eurocopter Deutschland GmbH Helicopters: Docket No. FAA-2013-0340; Directorate Identifier 2010-SW-081-AD. (a...

  13. 78 FR 54383 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-09-04

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Eurocopter Deutschland GmbH (ECD) EC 135 P1, P2, P2+, T1, T2, and T2+ helicopters equipped with a certain... directive (AD): 2013-16-14 Eurocopter Deutschland GmbH: Amendment 39-17552; Docket No. FAA-2013-0239...

  14. 78 FR 16196 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Science.gov (United States)

    2013-03-14

    ... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... directive (AD) for all Eurocopter Deutschland GmbH (ECD) EC 135 P1, P2, P2+, T1, T2, and T2+ helicopters... Airworthiness Directive (AD): Eurocopter Deutschland GmbH: Docket No. FAA-2013-0239; Directorate Identifier 2010...

  15. 14 CFR Appendix H to Part 36 - Noise Requirements For Helicopters Under Subpart H

    Science.gov (United States)

    2010-01-01

    ... Tone Corrected Perceived Noise Level (PNLTM). The reference flight path, ErKr represents a stable...) The helicopter must fly within ±10° or ±65 feet (±20 meters), whichever is greater, from the vertical... a height of 394 ±33 feet (120 ±10 meters) (3) The helicopter must fly within ±10° or ±65 feet (±20...

  16. Comprehensive aeroelastic analysis of helicopter rotor with trailing-edge flap for primary control and vibration control

    Science.gov (United States)

    Shen, Jinwei

    A comprehensive aeroelastic analytical model of helicopter rotors with trailing-edge flaps for primary and vibration controls has been developed. The derivation of system equations is based on Hamilton principles, and implemented with finite element method in space and time. The blade element consists of fifteen degrees of freedom representing blade flap, lag, torsional, and axial deformations. Three aerodynamic models of flapped airfoils were implemented in the present analysis, the unsteady Hariharan-Leishman model for trailing-edge flaps without aerodynamic balance, a quasi-steady Theodorsen theory for an aerodynamic balanced trailing-edge flap, and table lookup based on wind tunnel test data. The trailing-edge flap deflections may be modeled as a degree of freedom so that the actuator dynamics can be captured properly. The coupled trim procedures for swashplateless rotor are solved in either wind tunnel trim or free flight condition. A multicyclic controller is also implemented to calculate the flap control inputs for minimization of vibratory rotor hub loads. The coupled blade equations of motion are linearized by using small perturbations about a steady trimmed solution. The aeroelastic stability characteristics of trailing-edge flap rotors is then determined from an eigenanalysis of the homogeneous equations using Floquet method. The correlation studies of a typical bearingless rotor and an ultralight teetering rotor are respectively based on wind tunnel test data and simulations of another comprehensive analysis (CAMRAD II). Overall, good correlations are obtained. Parametric study identifies that the effect of actuator dynamics cannot be neglected, especially for a torsionally soft smart actuator system. Aeroelastic stability characteristics of a trailing-edge flap rotor system are shown to be sensitive to flap aerodynamic and mass balances. Key parameters of trailing-edge flap system for primary rotor control are identified as blade pitch index angle

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

    Directory of Open Access Journals (Sweden)

    Jialiang Wang

    2014-01-01

    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.

  18. Helicopter rotor induced velocities theory and experiment

    Science.gov (United States)

    Berry, John D.; Hoad, Danny R.; Elliott, Joe W.; Althoff, Susan L.

    1987-01-01

    An investigation has been performed to assess methods used for rotor inflow modeling. A key element of this assessment has been the recent acquisition of high quality experimental measurements of inflow velocities taken in the proximity of a lifting rotor in forward flight. Widely used rotor performance predictive methods are based on blade element strip theory coupled with an inflow model. The inflow prediction models assessed in this paper include the uniform inflow based on momentum, a skewed disk model, and two methods based on a vortex wake structure.

  19. Energetics of load carrying in Nepalese porters.

    Science.gov (United States)

    Bastien, Guillaume J; Schepens, Bénédicte; Willems, Patrick A; Heglund, Norman C

    2005-06-17

    Nepalese porters routinely carry head-supported loads equal to 100 to 200% of their body weight (Mb) for many days up and down steep mountain footpaths at high altitudes. Previous studies have shown that African women carry head-supported loads of up to 60% of their Mb far more economically than army recruits carrying equivalent loads in backpacks. Here we show that Nepalese porters carry heavier loads even more economically than African women. Female Nepalese porters, for example, carry on average loads that are 10% of their Mb heavier than the maximum loads carried by the African women, yet do so at a 25% smaller metabolic cost.

  20. A study of the application of differential techniques to the global positioning system for a helicopter precision approach

    Science.gov (United States)

    Mccall, D. L.

    1984-01-01

    The results of a simulation study to define the functional characteristics of a airborne and ground reference GPS receiver for use in a Differential GPS system are doumented. The operations of a variety of receiver types (sequential-single channel, continuous multi-channel, etc.) are evaluated for a typical civil helicopter mission scenario. The math model of each receiver type incorporated representative system errors including intentional degradation. The results include the discussion of the receiver relative performance, the spatial correlative properties of individual range error sources, and the navigation algorithm used to smooth the position data.

  1. Helicopter Electromagnetic and Magnetic Geophysical Survey Data for Portions of the North Platte River and Lodgepole Creek, Nebraska, June 2008

    Science.gov (United States)

    Smith, Bruce D.; Abraham, Jared D.; Cannia, James C.; Hill, Patricia

    2009-01-01

    This report is a release of digital data from a helicopter electromagnetic and magnetic survey that was conducted during June 2008 in areas of western Nebraska as part of a joint hydrologic study by the North Platte Natural Resource District, South Platte Natural Resource District, and U.S. Geological Survey. The objective of the contracted survey, conducted by Fugro Airborne, Ltd., was to improve the understanding of the relationship between surface water and groundwater systems critical to developing groundwater models used in management programs for water resources. The survey covered 1,375 line km (854 line mi). A unique aspect of this survey is the flight line layout. One set of flight lines were flown paralleling each side of the east-west trending North Platte River and Lodgepole Creek. The survey also included widely separated (10 km) perpendicular north-south lines. The success of this survey design depended on a well understood regional hydrogeologic framework and model developed by the Cooperative Hydrologic Study of the Platte River Basin. Resistivity variations along lines could be related to this framework. In addition to these lines, more traditional surveys consisting of parallel flight lines separated by about 270 m were carried out for one block in each of the drainages. These surveys helped to establish the spatial variations of the resistivity of hydrostratigraphic units. The electromagnetic equipment consisted of six different coil-pair orientations that measured resistivity at separated frequencies from about 400 Hz to about 140,000 Hz. The electromagnetic data along flight lines were converted to electrical resistivity. The resulting line data were converted to geo-referenced grids and maps which are included with this report. In addition to the electromagnetic data, total field magnetic data and digital elevation data were collected. Data released in this report consist of data along flight lines, digital grids, and digital maps of the

  2. Evaluation of the Environmental Impact and Recommended Control Measures to Reduce the Noise Generated from Military Helicopter Operations at the McGuire Veterans Administration Hospital, Richmond, Virginia

    Science.gov (United States)

    1974-10-01

    Civil Engineering Planning and Progranning; Land Use Planning with Respect to Aircraft Noise, 1 October 1964. b. The Noise Control Act of 1972...area (Figure 8, Appendix A). * P° ea ™ a map of the a-i J?! The US En^ironlnental Proteccion Agency has recently deveüoped a guideline on a...Application," NASA CR-132430 (1974). 19 Ernest G. Hinterkeuser and Harry Stemfeld, " Civil Helicopter Noise Assessment Study: Boeing Vertol Model 347," NASA

  3. Parasite-Drag Measurements of Five Helicopter Rotor Hubs

    Science.gov (United States)

    Churchill, Gary B.; Harrington, Robert D.

    1959-01-01

    An investigation has been conducted in the Langley full-scale tunnel to determine the parasite drag of five production-type helicopter rotor hubs. Some simple fairing arrangements were attempted in an effort to reduce the hub drag. The results indicate that, within the range of the tests, changes in angle of attack, hub rotational speed, and forward speed generally had only a small effect on the equivalent flat-plate area representing parasite drag. The drag coefficients of the basic hubs, based on projected hub frontal area, increased with hub area and varied from 0.5 to 0.76 for the hubs tested.

  4. Advanced Technology Helicopter Landing Gear Preliminary Design Investigation

    Science.gov (United States)

    1985-10-01

    helicopter studied, the criteria for attitudes and sink rates to develop landing gear loads should be as follows: * The peak design load in the shock...baseline shock struts and the shock struts required for the peak load at 42 feet per second -5 deg pifrh and 15 deg roll. Baseline design load Peak ... design load P = 50,390 lb P = 57,000 lbcB C Pressure = 6074 psi Pressure = 6870 psi Lower Piston Sections C-C and G-G (Figures 26 and 27) O-D = 3.250 4340

  5. A flight dynamics investigation of compound helicopter configurations

    OpenAIRE

    Ferguson, K.; Thomson, D.

    2013-01-01

    Compounding has often been proposed as a method to increase the maximum speed of the helicopter. There are two\\ud common types of compounding known as wing and thrust compounding. Wing compounding offloads the rotor at\\ud high speeds delaying the onset of retreating blade stall, hence increasing the maximum achieveable speed, whereas\\ud with thrust compounding, axial thrust provides additional propulsive force. The concept of compounding is not new\\ud but recently there has been a resurgence o...

  6. Multilevel Analysis of Continuous AE from Helicopter Gearbox

    Czech Academy of Sciences Publication Activity Database

    Chlada, Milan; Převorovský, Zdeněk; Heřmánek, Jan; Krofta, Josef

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] R&D Projects: GA MPO FR-TI3/755 Institutional support: RVO:61388998 Keywords : structural health monitoring (SHM) * signal processing * acoustic emission (AE) * diagnostics of helicopter gearbox * wavelet analysis * continuous acoustic emission Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts http://www.ndt.net/events/ECNDT2014/app/content/Paper/630_Chlada_Rev1.pdf

  7. Hydrogen Fuel Cell on a Helicopter: A System Engineering Approach

    Science.gov (United States)

    Nesheiwat, Rod

    Hydrogen fuel cells have been previously investigated as a viable replacement to traditional gas turbine auxiliary power unit onboard fixed wing commercial jets. However, so far no study has attempted to extend their applicability to rotary wing aircrafts. To aid in the advancement of such innovative technologies, a holistic technical approach is required to ensure risk reduction and cost effectiveness throughout the product lifecycle. This paper will evaluate the feasibility of replacing a gas turbine auxiliary power unit on a helicopter with a direct hydrogen, air breathing, proton exchange membrane fuel cell, all while emphasizing a system engineering approach that utilize a specialized set of tools and artifacts.

  8. Local Dynamic Stability Associated with Load Carrying

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2013-03-01

    Conclusion: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.

  9. Optimising the allocation of groundwater carrying capacity in a data ...

    African Journals Online (AJOL)

    An analysis model of groundwater carrying capacity was then established and is solved with the Lagrange multiplier method. A case study of groundwater resource carrying capacity in 2010 and 2015 in the Yaoba Oasis irrigation district, Alxa Left Prefecture, Inner Mongolia Autonomous Region, China, was performed.

  10. System-Integrated Finite Element Analysis of a Full-Scale Helicopter Crash Test with Deployable Energy Absorbers

    Science.gov (United States)

    Annett, Martin S.; Polanco, Michael A.

    2010-01-01

    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.

  11. A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 1: Technical discussion and results

    Science.gov (United States)

    Lebacqz, J. V.; Forrest, R. D.; Gerdes, R. M.

    1982-01-01

    A ground-simulation experiment was conducted to investigate the influence and interaction of flight-control system, fight-director display, and crew-loading situation on helicopter flying qualities during terminal area operations in instrument conditions. The experiment was conducted on the Flight Simulator for Advanced Aircraft at Ames Research Center. Six levels of control complexity, ranging from angular rate damping to velocity augmented longitudinal and vertical axes, were implemented on a representative helicopter model. The six levels of augmentation were examined with display variations consisting of raw elevation and azimuth data only, and of raw data plus one-, two-, and three-cue flight directors. Crew-loading situations simulated for the control-display combinations were dual-pilot operation (representative auxiliary tasks of navigation, communications, and decision-making). Four pilots performed a total of 150 evaluations of combinations of these parameters for a representative microwave landing system (MLS) approach task.

  12. Active fault tolerant control based on interval type-2 fuzzy sliding mode controller and non linear adaptive observer for 3-DOF laboratory helicopter.

    Science.gov (United States)

    Zeghlache, Samir; Benslimane, Tarak; Bouguerra, Abderrahmen

    2017-11-01

    In this paper, a robust controller for a three degree of freedom (3 DOF) helicopter control is proposed in presence of actuator and sensor faults. For this purpose, Interval type-2 fuzzy logic control approach (IT2FLC) and sliding mode control (SMC) technique are used to design a controller, named active fault tolerant interval type-2 Fuzzy Sliding mode controller (AFTIT2FSMC) based on non-linear adaptive observer to estimate and detect the system faults for each subsystem of the 3-DOF helicopter. The proposed control scheme allows avoiding difficult modeling, attenuating the chattering effect of the SMC, reducing the rules number of the fuzzy controller. Exponential stability of the closed loop is guaranteed by using the Lyapunov method. The simulation results show that the AFTIT2FSMC can greatly alleviate the chattering effect, providing good tracking performance, even in presence of actuator and sensor faults. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Requirements for a Hydrogen Powered All-Electric Manned Helicopter

    Science.gov (United States)

    Datta, Anubhav

    2012-01-01

    The objective of this paper is to set propulsion system targets for an all-electric manned helicopter of ultra-light utility class to achieve performance comparable to combustion engines. The approach is to begin with a current two-seat helicopter (Robinson R 22 Beta II-like), design an all-electric power plant as replacement for its existing piston engine, and study performance of the new all-electric aircraft. The new power plant consists of high-pressure Proton Exchange Membrane fuel cells, hydrogen stored in 700 bar type-4 tanks, lithium-ion batteries, and an AC synchronous permanent magnet motor. The aircraft and the transmission are assumed to remain the same. The paper surveys the state of the art in each of these areas, synthesizes a power plant using best available technologies in each, examines the performance achievable by such a power plant, identifies key barriers, and sets future technology targets to achieve performance at par with current internal combustion engines.

  14. Helicopter Scene Response for Stroke Patients: A 5-Year Experience.

    Science.gov (United States)

    Hawk, Andrew; Marco, Catherine; Huang, Matt; Chow, Bonnie

    The purpose of this study was to examine the usefulness of an emergency medical service (EMS)-requested air medical helicopter response directly to the scene for a patient with clinical evidence of an ischemic cerebrovascular accident (CVA) and transport to a regional comprehensive CVA center. CareFlight, an air medical critical care transportation service, is based in Dayton, OH. The 3 CareFlight helicopters are geographically located and provided transport to all CVA scene patients in this study. A retrospective chart review was completed for all CareFlight CVA scene flights for 5 years (2011-2015). A total of 136 adult patients were transported. EMS criteria included CVA symptom presence for less than 3 hours or awoke abnormal, nonhypoglycemia, and a significantly positive Cincinnati Prehospital Stroke Scale. The majority of patients (75%) met all 3 EMS CVA scene criteria; 27.5% of these patients received peripheral tissue plasminogen activator, and 9.8% underwent a neurointerventional procedure. Using a 3-step EMS triage for acute CVA, air medical transport from the scene to a comprehensive stroke center allowed for the timely administration of tissue plasminogen activator and/or a neurointerventional procedure in a substantive percentage of patients. Further investigation into air medical scene response for acute stroke is warranted. Copyright © 2016 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

  15. Measures for simulator evaluation of a helicopter obstacle avoidance system

    Science.gov (United States)

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

    1993-01-01

    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. Sensor supported pilot assistance for helicopter flight in DVE

    Science.gov (United States)

    Waanders, Tim; Münsterer, T.; Kress, M.

    2013-05-01

    Helicopter operations at low altitude are to this day only performed under VFR conditions in which safe piloting of the aircraft relies on the pilot's visual perception of the outside environment. However, there are situations in which a deterioration of visibility conditions may cause the pilot to lose important visual cues thereby increasing workload and compromising flight safety and mission effectiveness. This paper reports on a pilot assistance system for all phases of flight which is intended to: • Provide navigational support and mission management • Support landings/take-offs in unknown environment and in DVE • Enhance situational awareness in DVE • Provide obstacle and terrain surface detection and warning • Provide upload, sensor based update and download of database information for debriefing and later missions. The system comprises a digital terrain and obstacle database, tactical information, flight plan management combined with an active 3D sensor enabling the above mentioned functionalities. To support pilots during operations in DVE, an intuitive 3D/2D cueing through both head-up and head-down means is proposed to retain situational awareness. This paper further describes the system concept and will elaborate on results of simulator trials in which the functionality was evaluated by operational pilots in realistic and demanding scenarios such as a SAR mission to be performed in mountainous area under different visual conditions. The objective of the simulator trials was to evaluate the functional integration and HMI definition for the NH90 Tactical Transport Helicopter.

  17. Effect of advanced component technology on helicopter transmissions

    Science.gov (United States)

    Lewicki, D. G.; Townsend, D. P.

    1989-01-01

    Experimental tests were performed on the NASA/Bell Helicopter Textron (BHT) 500 hp advanced technology transmission (ATT) at the NASA Lewis Research Center. The ATT was a retrofit of the OH-58C helicopter 236 kW (317 hp) main rotor transmission, upgraded to 373 kW (500 hp), with a design goal of retaining long life with a minimum increase in cost, weight, and size. Vibration, strain, efficiency, deflection, and temperature experiments were performed and the results were compared to previous experiments on the OH-58A, OH-58C, and UH-60A transmissions. The high-contact-ratio gears and the cantilevered-mounted, flexible ring gear of the ATT reduced vibration compared to that of the OH-58C. The ATT flexible ring gear improved planetary load sharing compared to that of the rigid ring gear of the UH-60A transmission. The ATT mechanical efficiency was lower than that of the OH-58A transmission, probably due to the high-contact-ratio planetary gears.

  18. [Fitness, carrying capacity and competition in an ecosystem].

    Science.gov (United States)

    Wedekind, J; Wöhrmann, K

    1975-01-01

    In this paper a model is introduced in which fitness, carrying capacity and competition are considered. Thereby as well genetic as ecological parameters were assumed to become active. It results from the investigations that: 1. Competition may compensate the influence of genotypic fitness. 2. The carrying capacity has a more important influence on the construction of a population than the genotypic fitness. 3. As well competition as carrying capacity are parameters which do influence not only the size of the populations but also the genotypic construction of the populations. Therefore for a description of populations it is necessary to take into account a polyfactorial system with genotypic fitness, carrying capacity and competition. The model proposed has been compared with those described in the literature. The importance of population fitness and by it the genetic load has been discussed considering ecological parameters such as competition and carrying capacity.

  19. Some thoughts on the implementation of pilot night vision devices for helicopters

    Science.gov (United States)

    Tucker, G. E.

    1984-01-01

    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.

  20. Development of an Attitude Sensor for a Cm-Sized Helicopter

    Science.gov (United States)

    Sunada, Shigeru; Tokutake, Hiroshi; Kikuchi, Atsushi; Kawashima, Kenta

    Our developed cm-sized helicopter is inclined with a large pitch angle by the nose down moment generated by the aft propeller when it goes forward and when it keeps its position against a wind. This is because the ratio of parasite drag to the gravitational force is larger for a smaller helicopter. And the horizontal component of aerodynamic force generated by the main rotors, which equals the parasite drag, should be larger. Then, a small and lightweight attitude sensor was newly developed to measure the large pitching angle of the helicopter and to control the rotational speed of the aft propeller. The principle is same as that of a solar sensor.