Helicopter Flight Simulator Research Articles

Tilt perception is different in the pitch and roll planes in human.

Neurophysiological tests probing the vestibulo-ocular, colic and spinal pathways are the gold standard to evaluate the vestibular system in clinics. In contrast, vestibular perception is rarely tested despite its potential usefulness in professional training and for the longitudinal follow-up of professionals dealing with complex man-machine interfaces, such as aircraft pilots. This is explored here using a helicopter flight simulator to probe the vestibular perception of pilots. The vestibular perception of nine professional helicopter pilots was tested using a full flight helicopter simulator. The cabin was tilted six times in roll and six times in pitch (-15°, -10°, -5°, 5°, 10° and 15°) while the pilots had no visual cue. The velocities of the outbound displacement of the cabin were kept below the threshold of the semicircular canal perception. After the completion of each movement, the pilots were asked to put the cabin back in the horizontal plane (still without visual cues). The order of the 12 trials was randomized with two additional control trials where the cabin stayed in the horizontal plane but rotated in yaw (-10° and +10°). Pilots were significantly more precise in roll (average error in roll: 1.15 ± 0.67°) than in pitch (average error in pitch: 2.89 ± 1.06°) (Wilcoxon signed-rank test: p< 0.01). However, we did not find a significant difference either between left and right roll tilts (p= 0.51) or between forward and backward pitch tilts (p= 0.59). Furthermore, we found that the accuracies were significantly biased with respect to the initial tilt. The greater the initial tilt was, the less precise the pilots were, although maintaining the direction of the tilt, meaning that the error can be expressed as a vestibular error gain in the ability to perceive the modification in the orientation. This significant result was found in both roll (Friedman test: p< 0.01) and pitch (p< 0.001). However, the pitch trend error was more prominent (gain=0.77 vs gain=0.93) than roll. This study is a first step in the determination of the perceptive-motor profile of pilots, which could be of major use for their training and their longitudinal follow-up. A similar protocol may also be useful in clinics to monitor the aging process of the otolith system with a simplified testing device.

To the problem of simulation modelling of abnormal and emergency flight situations in the process of Mi-8MTV helicopter pilot simulation training

The article examines a method of obtaining the required initial data for adequate mathematical modelling of nonstationary processes in the Mi-8MTV helicopter computer and flight simulators. The principle of the method is as follows: the video fixation of non-stationary modes of the power plant operation in a real flight and the computation of the obtained dependencies according to the known formulas of mechanics, aerodynamics, the theory of gas turbine aircraft engines, etc. are analysed. Moreover, by juxtaposing the computed dependencies and the obtained video fixation, the parameter values, that determine the helicopter power plant behaviour (the inertia moment of the helicopter main rotor system, etc.) in the non-stationary modes, are found. These parameters allow us to solve the problem by modelling a complete picture of the helicopter power plant behaviour in abnormal and emergency situations, under which, it is impossible to formulate an objective verdict without violating flight safety requirements. Given the circumstances, the feasibility of an advantageous and reliable solution to the problem is considered using mathematical modelling of the transient power plant operation modes both in non-stationary conditions and in abnormal and emergency situations. A simulation of these scenarios and responsive actions is carried out using helicopter simulators. In a real flight, a helicopter crew monitors the functional systems status and the development of abnormal and emergency situations relying on readings from dial instruments, digital indicators, annunciators, and other computer-aided facilities in the cockpit, not only by the parameter values, but also by dynamics of their variation in flight. Within this timespan, the pilot must assess an abnormal situation and decide on required actions.

Helicopter Flight Simulation Trim and Validation Using Hybrid Genetic Algorithm

Helicopter Flight Simulation Trim and Validation Using Hybrid Genetic Algorithm

An Approach to Developing Mathematical Software of On-Board Helicopter Flight Simulator Decision Support System

Abstract The work explores methods and develops aids to improve a pilot flight training level using Full Flight Simulators. It examines their didactic advantages over real helicopters by implementing on-board intelligent decision support systems (IDSS). These simulation programs monitor actions of learner, find the best ways to correct errors and generate appropriate instructions. The training is carried out by reference point methods while the helicopter flight dynamics model simulates a flight and helps an instructor in parallel. Sufficiently simple and accurate model of helicopter flight dynamics was selected and tested to assess the proposed methods and aids. Our analysis introduces a functional structure of IDSS as an adaptive control system with a reference model. We further conducted a study on developing models, methods and means of automatic analysis, forecasting, optimization and correction of actions. Combining single-criteria conditional and vector optimization methods, we found out optimal flight parameters. The research findings revealed that the chosen optimization method requires too many system resources for the optimal solution to be found in a short time. The study thereby comes up with applying ANNs to solve this problem.

Understanding the Effect of Rotor-to-Rotor Interference on CH-47D Helicopter Dynamics

During the development of the Boeing CH-47D helicopter flight simulation model, test pilots reported mismatch between the flight simulator results and flight test data of the hover and low-speed lateral axis handling qualities, especially for the case without the automatic flight control system. In addressing the observed mismatch, the gains of the longitudinal and lateral components of the inflow model were selected to be significantly higher than their theoretical values. In this study, a detailed understanding of the rotor-to-rotor inflow interference is pursued using a recently developed multi-rotor pressure potential superposition inflow model. It is shown that the coupling between the inflow gradients of individual rotors exists in a tandem rotor, which can be approximated by using higher values for the longitudinal and lateral inflow gains of individual rotors. Further, it is shown that the need for empirical tuning of aerodynamic hub moment influence factors can be eliminated by properly accounting for the rotor-to-rotor interference in the inflow model.

Piloted Flight Simulation of Helicopter Recovery to the Queen Elizabeth Class Aircraft Carrier

This Paper describes how flight simulation has been used to investigate helicopter recovery operations to the deck of HMS Queen Elizabeth, the United Kingdom’s new aircraft carrier. A helicopter flight simulation environment has been developed in which the unsteady airflow over the ship has been created using full-scale computational fluid dynamics. A six-degree-of-freedom motion flight simulator has been used to conduct real-time piloted deck landings where a helicopter flight dynamics model representative of a Sikorsky SH-60B Seahawk helicopter was recovered to the designated rotorcraft landing spots toward the stern of the ship. A test pilot was instructed to land the helicopter and to give workload ratings for the difficulty of the task when flying in relative winds from Ahead, and 45 deg and 90 deg from starboard. The workload ratings, along with the corresponding pilot control activity and helicopter positional accuracy, are discussed in relation to the airflow to which the helicopter was subjected. The Paper demonstrates how flight simulation could be used to support flight trials and helicopter clearance activities but also notes that real-world trials data are needed to compare with the simulations before the techniques can be beneficially deployed.

Dynamic parameters identification of a haptic interface for a helicopter flight simulator

Abstract. The haptic interface force feedback is one of the key factors for a reliable flight simulation. This paper addresses the design and control implementation of a simple joystick-like haptic interface to be used for a helicopter flight simulator. The expression of the haptic interface force is obtained by dynamic analysis of the haptic interface operation. This paper proposes a new strategy aiming at avoiding the use of an expansive and complex force/torque sensor. Accordingly, specific dynamic model is implemented by including Stribeck friction to describe the friction moment. Experimental data are processed as based on a genetic algorithm for identifying the dynamic parameters in the Stribeck friction model. This allows to obtain the friction moment parameters of the haptic interface, as well as the torque distribution due to gravity and the rotational inertia parameters of the haptic interface for the calculation of the haptic interface force. Experimental tests are carried out and results are used to validate the proposed dynamic model and dynamic parameter identification method and demonstrate the effectiveness of the proposed force feedback while using a cheap photoelectric sensor instead of an expansive force/torque sensor.

Helicopter stability and control derivatives identification in different flight conditions

Helicopter flight simulators require high-fidelity dynamic models based on a set of stability and control derivatives (SCDs). For different flight conditions, specific sets of SCDs must be identified and utilized in the flight simulator software. In this study, nine sets of SCDs of the AS 355 F2 helicopter have been estimated from experimental flight-testing data, considering different combinations of velocity, mass, and altitude. Linear dynamic models with eight states and four controls were determined for the different flight conditions, using the output-error method. The associated optimization problem was solved with the Gauss–Newton algorithm, and identification reliability was evaluated by the Cramer–Rao (CR) and relative correlation coefficient (RCC) indices. An instrumented AS 355 F2 Helicopter belonging to the Instituto de Pesquisas e Ensaios em Voo, Departamento de Ciencia e Tecnologia Aeroespacial, Sao Jose dos Campos, Brazil, was utilized for data collection in different flight conditions, totaling 16 test hours. The following natural dynamic modes have been excited: phugoid, short period, spiral and Dutch roll, by command inputs of the type: frequency sweep (sinusoidal), doublet pulse and 3-2-1-1. Considering CR and RCC criteria, the most appropriate maneuver for exciting each dynamic mode is suggested, and the sets of the nine flight conditions are SCDs reported.

Distributed Turbulence Model with Rigorous Spatial Cross-Correlation for Simulation of Helicopter Flight in Atmospheric Turbulence

This paper presents a distributed turbulence model with rigorous spatial cross-correlation for helicopter flight simulation in atmospheric turbulence and for future handling-quality analysis. First, digital filters with longitudinal correlations of the von Kármán turbulence are developed to generate discrete turbulence velocity components. Meanwhile, transverse turbulence correlations are considered by relating the filters in different positions with mathematically rigorous spatial cross-correlation. Then, the distributions of the related filters on the transverse plane in front of helicopter and their velocity components in the longitudinal direction of airspeed, as well as turbulence models of helicopter aerodynamic surfaces, are established. Finally, a flight dynamics model coupled with the turbulence model is developed and validated against the flight-test data. The proposed model can achieve accurate real-time simulations of helicopter response to atmospheric turbulence in the frequency range of interest of handling qualities. The effect of transverse turbulence correlations on helicopter frequency response is also analyzed. The results show that the simulation model regardless of transverse turbulence correlations would aggravate the "rotor-to-body attenuation" effect of the main rotor and therefore underpredict the helicopter roll, pitch, and heave rate responses to atmospheric turbulence in the frequency range of interest.

Helicopter Flight Simulation based on URANS Solver and Virtual Blade Model

Abstract The methodology of simulation of a rotorcraft flight has been developed and applied to simulate several stages of flight of light helicopter. The methodology is based on coupling of several computational models of Computational Fluid Dynamics, Flight Dynamic. The essence of the methodology consists in calculation of aerodynamic forces acting on the flying rotorcraft by solving during the simulation the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In this approach, the rotorcraft is flying inside the computational 3D mesh modelling the space filled with the air. The flight simulation procedure is completely embedded in the URANS solver ANSYS FLUENT. Flow effects caused by rotating blades of main or tail rotor are modelled by application of the developed Virtual Blade Model (VBM). In this approach, real rotors are replaced by volume discs influencing the flow field similarly as rotating blades. Time-averaged aerodynamic effects of rotating blades are modelled using momentum source terms placed inside the volume-disc zones. The momentum sources are evaluated based on the Blade Element Theory, which associates local flow parameters in the blade sections with databases of 2D-aerodynamic characteristics of these sections. Apart of the VBM module, two additional UDF modules support the simulation of helicopter flight: the module responsible for modelling of all kinematic aspects of the flight and the module gathering the momentary aerodynamic loads and solves 6 DOF-Equations describing a motion of the helicopter seen as solid body. Exemplary simulation of helicopter flight, starting from a hover, through an acceleration and fast flight until a deceleration and steep descent, has been discussed.

The reliability of thromboelastography in a simulated rotary wing environment

BackgroundWith the increasing role of point-of-care coagulation testing in trauma, we sought to test the reliability of the thromboelastography (TEG)6s machine in a simulated rotary wing environment.MethodA two-arm study was...

Helicopter flight simulation trim in the coordinated turn with the hybrid genetic algorithm

Helicopter trim models are multivariate nonlinear equations and it is difficult to determine these initial trim points comparable to flight conditions. To solve this question, a hybrid genetic algorithm is presented in this paper, that combines the quick convergence ability of the quasi-Newton method and the advantages of genetic algorithm, such as global convergence. The trim control vector and the constraint conditions were established in the coordinated-turn based on the helicopter flight dynamic model. The coordinated turn flight of a UH-60 A helicopter was taken as an example to simulate on the experimental platform. Comparisons were made between the trim results and flight test data and there is a good agreement among them, and the efficiency of the algorithm presented is verified. It is a general method that can be applied to trim the helicopter of different flight conditions.

Analysis of Helicopter Handling Quality in Turbulence with Recursive Von Kármán Model

A recursive von Kármán turbulence model is developed and integrated into the current distributed turbulence model for helicopter flight simulation and handling quality analysis in atmospheric turbulence. First, high-order filters are developed with rational expressions to approximate the von Kármán spectra. Recursive algorithms for modeling the von Kármán turbulence are derived by discretizing the filters with the Tustin transform. Then, the recursive von Kármán turbulence model is used to replace the Dryden model in the current distributed turbulence model for helicopter flight simulation in atmospheric turbulence. The results show that the spectra of the recursive von Kármán turbulence have an excellent agreement with the theoretical von Kármán spectra, and they are valid over a normalized frequency range up to 400 rad, which is suitable for helicopter handling quality analysis in atmospheric turbulence with low flight speed and large turbulence scale lengths. The present turbulence model significantly extends the capability of helicopter handling quality analysis to the higher-altitude and lower-velocity flight conditions compared with the current distributed turbulence model.

Response of Flight Nurses in a Simulated Helicopter Environment

ObjectiveThe purpose of this study was to determine if a helicopter flight simulator could provide a useful educational platform by creating experiences similar to those encountered by actual flight nurses. MethodsFlight nurse (FN) and non-FN participants completed a simulated emergency scenario in a flight simulator. Physiologic and psychological stress during the simulation was measured using heart rate and perceived stress scores. A questionnaire was then administered to assess the realism of the flight simulator. ResultsSubjects reported that the overall experience in the flight simulator was comparable with a real helicopter. Sounds, communications, vibrations, and movements in the simulator most approximated those of a real-life helicopter environment. Perceived stress levels of all participants increased significantly from 27 (on a 0-100 scale) before simulation to 51 at the peak of the simulation and declined thereafter to 28 (P < .001). Perceived stress levels of FNs increased significantly from 25 before simulation to 54 at the peak of the simulation and declined thereafter to 30 (P < .001). Perceived stress levels of non-FNs increased significantly from 31 before simulation to 49 at the peak of the simulation and declined thereafter to 25 (P < .001). There were no significant differences in perceived stress levels between FNs and non-FNs before (P = .58), during (P = .63), or after (P = .55) simulation. FNs' heart rates increased significantly from 77 before simulation to 100 at the peak of the simulation and declined thereafter to 72 (P < .001). ConclusionThe results of this study suggest that simulation of a critical care scenario in a high-fidelity helicopter flight simulator can provide a realistic helicopter transport experience and create physiologic and psychological stress for participants.

Distributed Atmospheric Turbulence Model for Helicopter Flight Simulation and Handling-Quality Analysis

A distributed atmospheric turbulence model is developed for helicopter flight simulation. The impacts of different aerodynamic surfaces on handling qualities with helicopter in turbulence are analyzed. Both helicopter flight dynamic model and turbulence model are validated against the flight test data, which shows that the proposed model improves the accuracy of the simulation of rotor blade element turbulence model on the vertical axis within the interested frequency range for handling-quality analysis. A quantitative index is developed to study the impact of turbulence on helicopter handling qualities by analyzing the effects of different aerodynamic surfaces on helicopter response to turbulence. The results show that the main rotor has the dominant effects on both the heave and roll handling qualities, the airframe has the primary effect on the pitch handling quality, and the tail rotor has an important effect on the yaw handling quality. Furthermore, the impacts of the main rotor in turbulence on the helicopter handling qualities of roll, pitch, and yaw increase with the forward speed at lower speeds but decrease at higher speeds. The increment trend with the forward speed of the airframe’s impacts on the pitch and yaw handling qualities reduces at higher speeds.

Interprofessional Flight Camp Attracts 29 Graduate Nurses From Puerto Rico

The Dorothy Ebersbach Academic Center for Flight Nursing in Cleveland, OH, holds an annual flight camp designed for master's degree nursing students in the acute care nurse practitioner program, subspecializing in flight nursing at the Frances Payne Bolton School of Nursing at Case Western Reserve University. The weeklong interprofessional training is also open to any health care provider working in an acute care setting and focuses on critical care updates, trauma, and emergency care within the critical care transport environment. This year, 29 graduate nursing students enrolled in a master's degree program from Puerto Rico attended. Although the emergency department in Puerto Rico sees and cares for trauma patients, there is no formal trauma training program. Furthermore, the country only has 1 rotor wing air medical transport service located at the Puerto Rico Medical Center in San Juan. Flight faculty and graduate teaching assistants spent approximately 9 months planning for their participation in our 13th annual flight camp. Students from Puerto Rico were extremely pleased with the learning experiences at camp and expressed particular interest in having more training time within the helicopter flight simulator.

Calculation method of blade element aerodynamic loads based on small perturbation theory

A calculation method of blade element aerodynamic loads based on small perturbation theory is established for helicopter flight simulation application. The method synthesizes flap-lag-torsion elastic rotor blade mode,couples rotor dynamic inflow,unsteady aerodynamics model with dynamic stall and rotor trimming model. The entire model is developed in a standard state-space form. To verify this model,the UH-60 A helicopter is taken as an example,and the effects of yaw flow on rotor aerodynamic performance are studied at low speed flight and high speed flight. It is shown that yaw flow has a greater effect on rotor aerodynamic performance at high speed flight. Blade induced velocity fields and aerodynamic loads are simulated,and the results are compared with flight test data. It is shown by the results that the method can accurately predict the unsteady aerodynamic rotor loads in steady flight by capturing its variational characteristics along blade azimuthal locations,and it is still applicable for high speed flight.

Roles of Size, Position, and Speed of Stimulus in Vection with Stimuli Projected on a Ground Surface.

Although the induction of vection (perception of illusory self-motion) has been studied for some decades, the effect of ground surface properties on vection remains to be assessed quantitatively. This study will be helpful for designing helicopter or airplane flight simulation, because pilots often perceive optic flow on the ground surface and perceive self-motion from such flows. Vection stimuli of variable position, size, and optic flow speed were presented in a trapezoidal area on a ground surface. Body sway was also measured. Substantial vection was induced by stimuli on a ground surface. Increases in stimulus speed and size were each associated with stronger vection (e.g., the subjective strength increased by 50% as the speed increased from 0.375 m·s(-1) to 1.5 m·s(-1)). When the stimulus occupied a more distant section of the visual field, vection was more efficiently induced than when the nearer section was occupied (e.g., the subjective strength decreased by 50% when the nearer half section of optical flow was removed). These properties of vection were similar to vection induced by upright vertical stimuli. Speed, size, and position of vection stimuli modified both length and direction of body sway significantly. Vection and body sway showed some correlations (e.g., r=0.55). Stimuli on ground surfaces can induce substantial vection and vection strength can be modified by the stimulus properties of the ground surfaces.

An IDRA approach for modeling helicopter based on Lagrange dynamics

In order to accelerate the algorithm speed of dynamic model of helicopter, an IDRA approach for modeling helicopter was proposed and a dynamic model of six degrees of freedom (6 DOF) combining flying and landing was established in this paper. As the dynamic model is derived from the Lagrange equation of a non-conservative system, treating micro displacements and rotating angles of airframe in a simulation step as generalized coordinates, the relationship between energy dissipation, kinetic energy, potential energy and the generalized coordinates was analyzed. Finally, the reliability of this method and real-time of dynamic model were verified on the experimental platform of helicopter flight simulator, which could provide reliable theoretical foundation for solving the retardance of data transfer of helicopter simulator.

Implementation of artificial neuron networks for the simulation of loads generated by the helicopter main rotor

The possibility of applying the mathematical apparatus of artificial neural networks for simulating the loads, created by the helicopter rotors, is investigated. The effect of the network characteristics on the calculated root-mean-square error of parameters being simulated is evaluated on examples. The future prospect of this simulation method in the flight dynamics mathematical models of a helicopter flight simulator is demonstrated.