Introduction

A method for developing and performing a rotorcraft flight simulation in a bluff body airwake is investigated and compared to flight test data. This method is broadly composed of two parts: an atmospheric boundary layer computational solution that is unsteady and time-accurate, and a UH-60 flight dynamics program that can be coupled with an airwake developed from the atmospheric boundary layer solution. The flight dynamics program is a MATLAB/SIMULINK implementation of the GENHEL model. The computational fluid dynamics airwake solution is developed to recreate the airwake present for the validation case flight tests that were used to collect the flight test data. The validation case f light test data was collected from a variety of station-keeping tasks performed in the wake of a hangar on land. Two kinds of flight simulations were performed: piloted simulations in a flight simulator facility and flight simulations performed using a pilot model. Comparisons of the power spectral density analyses of pilot control stick activity reveal that pilots in the simulated flight tests use a generally higher level of control activity energy than the pilots of the f light test validation case. Limited simulator flight test data showed sizeable differences in pilot control activity for the same simulated flight task flown by different pilots. Significant unknowns remain in comparing a simulated flight to a physical flight. The pilot model was not used to compare simulated flights to validation case flights, but was useful for comparing different flight simulation cases to each other as well as for analyzing sensitivity of flight simulations to positioning error within a simulated airwake. The pilot model flight simulations show that flight tasks performed in an airwake produced using a high-fidelity atmospheric boundary layer simulation require more pilot control input power than airwakes made using a comparable mean wind speed uniform inflow.

This paper presents a comparison of the motion produced by a flight simulator using conventional washout filters and a novel robust controller. Both approaches are implemented in an off-line Matlab/Simulink simulation which includes a model of an electrically-driven synergistic motion base flight simulator. In order to evaluate the performance of these motion base control approaches, the Boeing 747 airliner has been simulated using a nonlinear model of its dynamics. The motion experienced by the aircraft pilot is compared to that experienced by the simulator pilot, using both control approaches. Additionally, the model used for the simulator motion base is adjusted to represent two different scenarios: a highand a low-fidelity motion system. It is shown that the two control approaches reasonably track the motion of the aircraft, within the limitations of the motion base, but that the robust controller is able to compensate for variations in the fidelity of the motion system.

Flight simulators can recreate aircraft flights for flight training and aircraft design. This paper reviews existing engineering flight simulators and introduces the development of a multi-purpose reconfigurable engineering flight simulator at Ryerson University. The multi-purpose engineering flight simulator named the Ryerson Fixed Base Simulator (RFBS) has been designed and built to teach and initiate research projects in the area of aircraft design, flight simulation, pilot training, and flight data analysis. It consists of three 46 inch high definition screens and six 22 inch touch screen panels to represent the instrument panel, the centre console, and the overhead panels of an actual aircraft flight deck. Several low-cost, commercial flight simulation software were tested and X-Plane was selected as the main flight simulation tool. This paper also introduces a research that utilizes the RFBS and a commercial flight analysis software. The objective of the research was to develop a flight data conversion methodology. A case study was commenced to verify the work flow of flight data generation and analysis with an example of hard-landing analysis.

This paper studies the feasibility of applying the stochastic gain tuning method to the flight control system design of space vehicles. Stochastic gain tuning is a form of parameter optimization by which. the probability of the flight control system’s total mission achievement is maximized. This probability is estimated by applying the Monte Carlo method to the results of a large number of simulated flights. The flight simulation model contains various types of uncertain parameter, the stochastic properties of which are defined a priori. The flight control system requirements are defined based on the flight simulation results, and an optimization algorithm called the mean tracking technique is used to tune the feedback/feedforward gains of the flight control laws, which maximizes the probability of mission achievement. Although stochastic gain tuning requires large computational resources, the recent advent of low-cost, high-performance computers means that it has become feasible and practicable if efficient computational algorithms are employed. This paper demonstrates its feasibility by applying it to the designof the flight control system of a re-entry space vehicle, a low-speed sub-scaled model of which was flight tested in 1996.

An image processing system with variety of visual techniques has been designed and implemented to support the detailed analysis of land surface. The strong points of this system are dynamic algorithm-save-method for efficient handling of the huge size image, automatic menu generation and powerful visual programming environment. Most of the existing image processing systems use general graphic user interfaces. The authors adopted visual program language for remotely sensed image processing for its powerful programmability and ease of use. This system is an integrated raster/vector analysis system and equipped with many special functions such as vector overlay, flight simulation, 3D simulation, and object modeling techniques etc. In addition to the modules for image and digital signal processing, the system provides many other utilities such as toolbox, an interactive image editor. This paper also presents several cases of image analysis methods and design concept for visual programming environment.

A visually effective stereoscopic CRT display technique has been developed which uses continuous tone computer graphics in combination with electro-optic shutter viewing devices. The technique involves the generation of left and right perspective views of an object model using continuous tone computer graphics. The perspective views constitute stereo pairs and are displayed in an alternating manner on the even and odd field scans of a conventional 2:1 interlace raster scan CRT display. When viewed with electro-optic shutters operated synchronously with the CRT field scan rate, the alternating perspective views are perceived as stereoscopic images with strong binocular depth-of-field sensations. Lightweight stereoscopic viewing glasses have been developed which use lead lanthanum zirconate titanate (PLZT) ceramics as electronically controlled shutter elements. Representative applications of the stereoscopic display technique to dynamic flight simulation and complex molecular modeling are presented. The flight simulation illustrates a landing sequence on an aircraft carrier while the modeling application shows complex three-dimensional structures of double helix DNA and bacterial ferredoxin molecules. The stereoscopic display technique has been shown to be highly effective for adding binocular depth-of-field to computer graphics displays with a resulting enhancement of object model realism.

Flight simulator for civil aircraft can be used for pilot training. The flight test data for modelling, verification, validation, and qualification of flight simulator can be obtained through flight simulator data package flight test. In order to improve the efficiency of flight test and save the resources of flight test, the planning of flight simulator data package flight test was studied. Four principles of flight test planning were proposed, considering the requirements of flight simulator development progress, flight test planning of aircraft, aircraft configuration plan, requirements of flight simulator data package flight test and aircraft flight test. The principles included the principle of flight test method similarity, the principle of progress priority, the principle of pre-test meeting and the principle of considering configuration requirements. The principles of flight test planning given in this paper have been applied in the actual planning of flight simulator data package flight test for a certain aircraft, and the efficiency of flight test has been improved.

Between 2018 and 2020 the NATO Science and Technology Organization (STO) engaged a Research Task Group (RTG) on rotorcraft flight simulation model fidelity. The primary goal of this RTG was to apply and compare flight simulation model enhancement methods and fidelity assessment criteria based on flight-test case studies. Under the AVT panel 296 (Applied Vehicle Technology), 20 partners from NATO nations' industries, governmental research establishments and universities tested 7 different model updating or "renovation" methods through comparison of simulation models vs flight data. Comparisons between update methods have been investigated to find best practices and suitability for different applications including advanced rotorcraft configurations. Most of the existing methods make extensive use of System Identification (SID) to generate improved-fidelity state-space models. Thereafter, these models are used as a reference for nonlinear model improvements. Among the case-studies carried-out, ONERA, US-Army and THALES Training and Simulation run a collaborative work to investigate the potential use of flight data from simulator’s Qualification Test Guides (QTG) in System Identification. The objective behind this work was to assess whether the state-space models resulting from this identification could be used and contribute to enhance the physics-based model. The renovation technique based on deltas of forces and moments was applied to select the most relevant derivatives of the identified model. The analysis of the derivatives helped identify some improvement axes of the physics-based model. This paper will present the work carried out in the scope of this collaboration.

The design of guidance and control strategies is a promising study trend of dynamic soaring for small unmanned aerial vehicles, for which the flight modeling and simulation specifically for soaring-capable unmanned aerial vehicles is significant and necessary. The aim of this paper is to propose a flight simulation platform for dynamic soaring. In order to do so, firstly, two different sets of equations of motion of small unmanned aerial vehicles have been derived and their characteristics are compared: one is expressed in body-fixed frame and the other in air-relative flight path frame. Secondly, the latter set is used for energy analysis to maximize energy gain while climbing and diving and minimize energy cost during turning in dynamic soaring. While the former serves to build the dynamic soaring simulation platform, in which a piecewise trajectory-based guidance and control strategy according to the energy analysis is proposed tracking the optimum climb and bank angles and traveling toward desired directions. Simulation results indicate that the unmanned aerial vehicles can perform dynamic soaring toward various directions in different wind fields, follow asymptotically the typical straight-line and circular-orbit paths by repeating soaring cycles.

We developed the virtual cockpit as an inexpensive flight simulator, using off-the-shelf equipment. This system functions as a component of a distributed interactive simulation. Any flight simulator has three principal tasks: image display, image generation, and flight dynamics. We built the flight simulator, the virtual cockpit, using a head-mounted display (HMD) to display the out-the-window imagery and the cockpit interior. The virtual cockpit consists of a Silicon Graphics workstation and supporting hardware components, such as an HMD and position tracker. The software falls into three areas by function: flight dynamics and cockpit instruments; network interface (either SimNet or DIS PDUs); and display of the out-the-window view. The virtual cockpit developed uses a multiprocessor Silicon Graphics Iris (the 4D/440VGXT) connected to a Polhemus Laboratories fiber-optic head-mounted display, a Polhemus magnetic head tracker and a hands-on-throttle-and-stick (HOTAS) by Thrustmaster. The software uses the AT and T C++ translator and the Silicon Graphics C compiler running under Irix 4.0.5. a Unix operating system. We use Software Systems' MultiGen to create the geometric models and the terrain database.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This study evaluated an anticipation-based training program for private pilots to recover from unusual flight attitudes, stalls, and spins using visual reference cues. Flight performance, psychophysiological measures of cardiac and electrodermal activity, and subjective measures of workload and emotion were collected from 33 pilots during simulated and real flight. The results demonstrate positive training effects of anticipation-based training in real and simulated flight to improve performance and to change patterns of psychophysiological arousal, workload, and emotion in pilots.

Digital projectors based on liquid crystal or micro-mirror technologies provide higher spatial resolution than the CRTs typically used in flight-simulator applications. However, their temporal response is limited by long hold-times. Hold-time is the interval that pixels are activated during each frame, and it is related to both the design of the driver circuitry and the display itself. Long hold-times result in the blurring of moving imagery, which can affect the detection and identification of simulated targets as well as the perceived realism of simulated scenes. Described here are the results of an evaluation of several digital projectors that implement various techniques for reducing pixel hold-time. The evaluation included estimates of both spatial and temporal resolution, as well as perceptual tests used to assess the validity of those estimates. The techniques described here can be used to assess the potential utility of candidate projectors for a given simulator application. The following projectors were tested: ferro-electric liquid crystal on silicon (FLCoS), liquid crystal on silicon (LCoS), liquid crystal (LCD), digital light projector (DLP, a digital micro-mirror device, or DMD), and cathode ray tube (CRT). The hold-time of the FLCoS and LCD projectors was varied using mechanical shutters, and the hold-time of the DLP projector was varied using an electronic shutter. The CRT and LCD projectors were used mainly for comparison and so their hold-times were not varied.

In order to evaluate the mental workload of the pilots during the flight, a flight simulation platform for Electroencephalography (EEG) experiment is developed. The platform uses a distributed flight simulation framework, and the flight visual is driven by a real flight dynamics equation. A common simulation parameter architecture based on Extensible Markup Language (XML) is introduced to meet the requirement of versatility. Flight simulation tasks can be designed by a programming interface based on the fight visual system. This platform provides experimental conditions for the further research on mental fatigue, mental workload and cockpit instrument interface ergonomic design.

State-space representation of the dynamic inflow is an essential element in rotorcraft flight mechanics modeling and simulation. Identification of a reliable low-order model which is able to predict the transient response of the inflow as well as the steady part, becomes even more important during the maneuvering flights. The objective of this paper is to exploit an experimental setup, consists of a helicopter model and a simplified ship geometry, to investigate the possible effect of the wake interactions with environmental elements such as ground effect or airwake of the ship, on the time constants associated with the buildup of the inflow states. A series of wind tunnel tests were performed, simulating various flight conditions, including hover and forward flight, inside and outside of the ground effect, and the rotor over the deck of the SFS1 at two different positions with respect to the ship super-structure, with the wind coming from two different directions. After trimming the rotor at each flight condition, a sequence of pitch excitation commands were applied to the collective, lateral and longitudinal cyclic in order to excite the induced flow of the rotor. The frequency analysis of the measured aerodynamic loads shows the variation of the time lag, while rotor is operating in the same trim condition, but different positions with respect to the ground or the flight deck.

The use of flight simulators for pilot training and evaluations is common in the modern aeronautical sector. Whether for airplanes or helicopters, the military and airline companies use this feature to keep their crews operational, safety-oriented and resource-saving. This work presents a proposal for adjusting the washout filter parameters that allows the use of Stewart's platform in helicopter simulators. The identification of the filter parameters was carried out based on tests on an available commercial platform, certified by the company Moog, model MB-E-6DOF/24/1800KG, currently used in the SHEFE helicopter simulator of the Brazilian Army. The work dealt with the physiological aspects of the human vestibular system and its dynamics. Subsequently, the methods for choosing the filter model, and configuration parameters are presented. Three series of tests were carried on the commercial platform and in a real helicopter prepared with special flight test instrumentation. The tests were completed, and the motion platform filter adjustments were made to minimize errors between the movement cues perceived by the pilot in the aircraft and the flight simulator. The results of this work will be used as a basis for the development of a national movement platform for another flight simulator in the development phase.