Ground-based Flight Simulators Research Articles

Closed-loop motion characteristic requirements of receiver aircraft for probe and drogue aerial refueling

To address the lack of flying qualities criteria for probe and drogue aerial refueling in conventional military flying qualities standards, this paper proposes new requirements for the closed-loop motion characteristic parameters of a receiver aircraft. By applying mission-oriented flying qualities evaluation approach, various closed-loop motion characteristics of the receiver aircraft are evaluated with a pilot-in-the-loop ground-based flight simulator. A comparison of the evaluation results with several conventional flying qualities criteria indicates that the closed-loop motion characteristic parameters used in the conventional flying qualities criteria cannot effectively reflect the motion characteristic requirements of the probe and drogue aerial refueling task. Based on analyses of the evaluation results and the characteristics of the probe and drogue aerial refueling task, quantitative requirements for longitudinal and lateral closed-loop motion characteristic parameters are proposed. The conclusions can be used to predict flying qualities and in the design of flight control laws for the probe and drogue aerial refueling mode.

MATHEMATICAL MODEL OF THE AIRCRAFT AERODYNAMICS IN A VORTEX WAKE

The process of the generation and evolution of the vortex wake behind an aircraft in turbulent atmosphere is considered. An artificial neural networks–based approach to the development of a mathematical model of the aerodynamics of an aircraft during in-flight refueling is proposed. The accuracy and speed of the developed software module were evaluated for the problem of in-flight refueling modeling using a ground-based flight simulator.

Control Allocation for an Over-Actuated Aircraft Based on Within-Visual-Range Air Combat Agility

The control allocation problems of an over-actuated aircraft are studied to fully utilize the within-visual-range (WVR) air combat agility. By analyzing the agility requirements of modern WVR air combat, a control effector superiority evaluating method is proposed to identify the control effectors participated in control allocation. An optimized control allocation model is constructed based on the air combat agility. As a case study, the control effector superiority parameters of a typical canard-delta-wing aircraft are evaluated, and the optimized control allocation configuration is built. The combat cycle times of the optimized and other two control allocation configurations are evaluated by pilot-in-the-loop simulation on a ground-based flight simulator. The simulation results show that the optimized control allocation model constructed in this paper can efficiently make use of the agility potentials of the target aircraft, which indicates that the control effector superiority evaluating method and the control allocation model proposed are sound and effective.

Evaluation of Airplane Upset Recovery Training

Loss of control is one of the leading factors in hull losses and fatalities in airline aircraft. To reduce the risk of this type of accident, four types of airplane upset recovery training have been developed (ground-based flight simulation, aerobatic flight, ground-based flight simulation with aerobatic flight, and in-flight simulation). These were evaluated during in-flight reenactments of fatal, hull loss airline airplane accidents. A between-subjects design, with five groups of eight nonmilitary pilots flying in their probationary year for airlines, was used to evaluate these types of training. Each group had received a different type of training, including one group that had received no training. Each pilot completed a 1.4-hr evaluation flight in which eight airplane upsets were introduced. For some scenarios, training clearly works – specifically, 39 evaluation pilots recovered from the wind shear upset. But few evaluation pilots used bank to change the direction of the lift vector to recover from nose-high upsets. Further, very few used differential thrust to recover from rudder- or aileron-induced roll upsets (use of alternate controls). Finally, recovery attempts from icing-induced stalls were generally inadequate.

Design/Development of Mini/Micro Air Vehicles through Modelling and Simulation: Case of an Autonomous Quadrotor

Normal 0 MicrosoftInternetExplorer4 Design and development of an autonomous quadrotor micro aerial vehicle is undertaken following a systematic approach. A fairly detailed model was constructed and simulations were then carried out with the purpose of refining the baseline design, building a controller, and testing the flying qualities of the vehicle on a ground-based flight simulator. Following this, a smooth transition to rig and flight testing has been enabled in a cost- and time-effective manner, meeting all the design requirements. Defence Science Journal, 2011, 61(4), pp.337-345 , DOI:http://dx.doi.org/10.14429/dsj.61.1086

The Influence of Simulator Motion on Handling Qualities

Ground-based flight simulation is a vital tool in the assessment of handling qualities. The strengths and weaknesses of ground-based flight simulators are well documented and understood, but the effects of individual simulator characteristics on handling qualities are not. This study compared the effect of three simulator motion states on handling qualities during a lateral tracking task using airplane models differing in lateral (roll) dynamics. Pilots' perception of the simulated aircraft's handling qualities were recorded in terms of Cooper–Harper ratings and subjective comments. The experiment was conducted on the motion simulator at the University of Toronto. Three highly qualified experimental test pilots with test pilot school backgrounds participated in the evaluation trials. The independent experiment variables were; lateral aircraft dynamics (roll mode time constant) and simulator motion states. The evaluation task consisted of tracking under roll gust upsets. Three values of the roll-mode time constant were tested under three different simulator motion states. These motion states were (a) fixed-base, (b) "very low" motion washout levels, and (c) "very high" washout levels. These states represented the extremes in useable simulator washout filter coefficients in the Flight Research Simulator (FRS). The results indicated that very low motion washout levels were preferred by pilots to fixed-base, while fixed-base was preferred to very high levels of motion washout.Some insight into pilot control strategies as a result of changes in motion state was also gained. The results suggested that pilot control strategy is driven by changes in motion state, for the same set of aircraft dynamics.

Modeling Human Pilot Cue Utilization with Applications to Simulator Fidelity Assessment

An analytical investigation to model the manner in which pilots perceive and utilize visual, proprioceptive, and vestibular cues in a ground-based flight simulator was undertaken. Data from a NASA Ames Research Center vertical motion simulator study of a simple, single-degree-of-freedom rotorcraft bob-up/down maneuver were employed in the investigation. The study was part of a larger research effort that has the creation of a methodology for determining flight simulator fidelity requirements as its ultimate goal. The study utilized a closed-loop feedback structure of the pilot/simulator system that included the pilot, the cockpit inceptor, the dynamics of the simulated vehicle, and the motion system. With the exception of time delays that accrued in visual scene production in the simulator, visual scene effects were not included in this study. Pilot/vehicle analysis and fuzzy-inference identification were employed to study the changes in fidelity that occurred as the characteristics of the motion system were varied over five configurations. The data from three of the five pilots who participated in the experimental study were analyzed in the fuzzy-inference identification. Results indicate that both the analytical pilot/vehicle analysis and the fuzzy-inference identification can be used to identify changes in simulator fidelity for the task examined.

Lynx Main Rotor/Tail Rotor Interactions: Mechanisms and Modelling

A flight trial has been conducted by the Defence Research Agency (DRA) Bedford using a Lynx AH Mk5 helicopter fitted with an instrumented tail rotor to collect data on tail rotor aerodynamic performance. The analysis carried out to date has concentrated on the effects of main rotor wake interactions on the tail rotor. This paper describes the trial and the analysis in broad outline and discusses in detail mechanisms to explain three out of the six main rotor/tail rotor interactions found. The modelling of these effects to improve the fidelity of ground-based flight simulation is also covered.

Performance Measurement during Simulated Air-to-Air Combat

Measurement and assessment of operator performance of complex tasks with decisional and psychomotor components of which only ultimate outcome measures are well defined provide difficult methodological challenges. One such task is the practice of air-to-air combat skills in simulated combat environments such as the Air Force Air Combat Maneuvering Instrumentation (ACMI) or ground-based visual flight simulators. Measurement and assessment of pilot performance in these environments are especially challenging because of the special cognitive and psychomotor skills involved in the freeplay and gamesmanship of two or more competing pilots. A review of the existing approaches to automated aircrew performance measurement was performed. Although the most common measurement models, using positional advantage or disadvantage, provide an adequate performance metric, other measures, such as control manipulation and the management of kinetic and potential energy, must be added to provide a refined performance measurement algorithm.

A microcomputer implementation of a turbulence generator for flight simulation

The inclusion of a realistic representation of atmospheric turbulence in ground-based flight simulation is an essential ingredient in providing the pilot with an authentic working environment, in addition to its possible importance in assessing the handling qualities of the particular aircraft being simulated. The Royal Aircraft Establishment Bedford and Newcastle upon Tyne Polytechnic have collaborated in the development of a model of turbulence suitable for digital simulation. As a FORTRAN subroutine it has been extensively validated and has an established reputation. This paper discusses the principal features of the model and describes the methods used to develop a micro-computer-based implementation designed to run in parallel with the main simulation. The conclusion is that a successful implementation is possible using an inexpensive standard system.

Visual Simulation Requirements for Aircraft Aspect Recognition at Real World Distances

A research program is underway whose goal is to provide engineering guidelines on target image sufficiency for training tactics and maneuvering skills in ground based flight simulators. A preliminary experiment was carried out in the Naval Training Equipment Center's Visual Technology Research Simulator (VTRS), using computer-generated aircraft images displayed on a dome via a variable-resolution target projector. The experiment examined aspect recognition sensitivity, or the distance at which subjects could determine the orientation of another aircraft. For our initial effort, the aspect (orientation) recognition task was simplified in the following ways: a) on each trial one of only 16 stationary target orientations of a TA4J aircraft was presented, b) targets had the same length/width ratio; c) subjects made binary up/down judgments; d) a staircase method provided thresholds for aspect recognition range. Four different target luminances, and three background luminances were combined with four different levels of projector resolution in a partial parametric study to assess the relative effects of contrast, resolution and brightness. All main effects were found to be significant. Over the ranges studied, contrast accounted for the most variance and brightness the least. In the best condition studied, aspect recognition was performed successfully at >4 miles (a 5.5 arc minute target), whereas the most degraded condition showed thresholds at 1.5 miles (a 14 arc minute target). These are comparable to distances known to be required in outdoor training ranges and in combat. An additional finding is that reliable subject differences were substantial (>20% of the total accounted for variance). The four subjects who were tested in this study had normal or better vision by static and dynamic tests of contrast sensitivity. Individual differences in these subjects' contrast sensitivity scores were predictive of their visual performance on this target aspect recognition task. These data are discussed from the standpoint of the utility of this paradigm for providing guidelines for training equipment design.

Simulator motion as a factor in flight-director display evaluation.

The results of research conducted in ground-based flight simulators must be interpreted with care in view of the potential effects of differences between the simulated and actual flight environments. A study comparing various flight-director displays in a moving-base simulator was replicated without motion. Significantly different results occurred as a function of the presence or absence of motion. Implications of these results raise doubt concerning the validity of findings from simulator experiments in which whole-body acceleration cues might be a factor.

Flight Simulation for Research

SummarySome of the uses of ground based flight simulation as a research tool to aid the design of new aircraft and their equipment are described. The function of the simulator is to provide a method for investigating humon flying tasks in the laboratory, so that the relationship between the pilot's capabilities and the equipment's characteristics can be systematically studied. The paper is presented in two parts describing recent work on two research simulators at the RAE.Part I deals with the use of simulation for studying aircraft stability and control characteristics. The equipment used at RAE for this work is described, with particular emphasis on methods of presenting to the pilot a simulated view of the outside world, and for reproducing some of the motion cues which he experiences in flight. Experimental evidence of the importance of these simulation cues when making aircraft control assessments is also presented. Several examples of simulation studies into the control of conventional and VTOL aircraft are given, to illustrate the type of research problems in this field which may be tackled and the techniques involved in solving them.