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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27

Analysis of longitudinal pilot-induced oscillation tendencies of YF-12 aircraft

Aircraft flight and ground tests and simulator studies were conducted to explore pilot-induced oscillation tendencies. Linear and nonlinear calculations of the integrated flight control system's characteristics were made to analyze and predict the system's performance and stability. The investigations showed that the small-amplitude PIO tendency was caused by the interaction of the pilot with a combination of the aircraft's short-period poles and the structural first bending mode zeros. It was found that the large-amplitude PIO's were triggered by abrupt corrective control actions by the pilot, which caused the stability augmentation system servo to position and rate limit. The saturation in turn caused additional phase lag, further increasing the tendency of the overall system to sustain a PIO.

Smith, J. W.↗

The Out of Service Guest Pilot Evaluation of the Two-segment Noise Abatement Approach in the Boeing B727-200

Guest pilot evaluation results of an approach profile modification for reducing ground level noise under the approach of jet aircraft runways are reported. Evaluation results were used to develop a two segmented landing approach procedure and equipment necessary to obtain pilot, airline, and FAA acceptance of the two segmented flight as a routine way of operating aircraft on approach and landing. Data are given on pilot workload and acceptance of the procedure.

Nylen, W. E.↗

A g-load display for remotely piloted vehicles and other aircraft that are subject to maneuvering constraints

The absence of kinesthetic cues deprives RPV pilots of essential feedback, particularly during high speed maneuvers. A display was designed to facilitate pilot control of g loads and to permit an immediate indication of g-load constraint violations. The display embodies all the motion vector components that contribute to maneuvering accelerations. In one mode of operation, the device displays the components of angular velocity as variable length pointers emanating from the center of a circle whose radius is determined by the linear velocity of the vehicle. An alternative mode of operation permits the pilot to select a display in which g loads are presented directly as variable length pointers emanating from the center of a circle whose radius is again determined by the linear velocity of the vehicle. Each circle defines a safe region of operation, and penetration of the circumference of the appropriate circle by a pointer implies that the structural design load was exceeded.

Howard, J. C.↗

A decision and control multi-axis pilot model based on an urgency for action concept

An all digital multiple axis, multiple input, multiple output pilot model flies five different tasks in aircraft of different classes while encountering turbulence represented by the Dryden spectral model. Six degree of freedom linearized aircraft equations of motion are used together with a generalized stability augmentation system. The pilot model consists of two parts: (1) a decision maker, and (2) a control action implementer. This decision maker selects the critical variable and predicts the error at action implementation. The control action implementer decides the magnitude of control to be applied and applies it. This system has been successfully compared with hybrid/analog man in the loop simulations of the F-5, A-7, T-33, and 707 aircraft, thus validating the all digital simulation and the decision and control pilot model.

Pollard, J. J.↗

Subsonic stability and control derivatives for an unpowered, remotely piloted 3/8-scale F-15 airplane model obtained from flight test

In response to the interest in airplane configuration characteristics at high angles of attack, an unpowered remotely piloted 3/8-scale F-15 airplane model was flight tested. The subsonic stability and control characteristics of this airplane model over an angle of attack range of -20 to 53 deg are documented. The remotely piloted technique for obtaining flight test data was found to provide adequate stability and control derivatives. The remotely piloted technique provided an opportunity to test the aircraft mathematical model in an angle of attack regime not previously examined in flight test. The variation of most of the derivative estimates with angle of attack was found to be consistent, particularly when the data were supplemented by uncertainty levels.

Iliff, K. W.↗

A piloted-simulation evaluation of two electronic display formats for approach and landing

The results of a piloted-simulation evaluation of the benefits of adding runway symbology and track information to a baseline electronic-attitude-director-indicator (EADI) format for the approach-to-landing task were presented. The evaluation was conducted for the baseline format and for the baseline format with the added symbology during 3 deg straight-in approaches with calm, cross-wind, and turbulence conditions. Flight-path performance data and pilot subjective comments were examined with regard to the pilot's tracking performance and mental workload for both display formats. The results show that the addition of a perspective runway image and relative track information to a basic situation-information EADI format improve the tracking performance both laterally and vertically during an approach-to-landing task and that the mental workload required to assess the approach situation was thus reduced as a result of integration of information.

Steinmetz, G. G.↗

Effect of color on pilot performance and transfer functions using a full-spectrum, calligraphic, color display system

The use of blue and red color in out-of-window cockpit displays, in full-spectrum calligraphic computer-generated display systems, is studied with attention given to pilot stereographic depth perception and response to visual cues. Displays for vertical approach, with dynamic and frozen-range landing approach and perspective arrays, are analyzed. Pilot transfer function and the transfer function associated with the contrasted approach and perspective arrays are discussed. Out-of-window blue lights are perceived by pilots as indicating greater distance depth, red lights as indicating proximity. The computer-generated chromatic display was adapted to flight simulators for the tests.

Chase, W. D.↗

The effect of visual-motion time-delays on pilot performance in a simulated pursuit tracking task

An experimental study was made to determine the effect on pilot performance of time delays in the visual and motion feedback loops of a simulated pursuit tracking task. Three major interrelated factors were identified: task difficulty either in the form of airplane handling qualities or target frequency, the amount and type of motion cues, and time delay itself. In general, the greater the task difficulty, the smaller the time delay that could exist without degrading pilot performance. Conversely, the greater the motion fidelity, the greater the time delay that could be tolerated. The effect of motion was, however, pilot dependent.

Miller, G. K., Jr.↗

Individual differences in pilot performance

Selected literature on individual differences in pilot performance is reviewed in order to indicate a possible direction for research. Approaches to studying pilot decision-making processes are discussed, with emphasis given to the wrong-model approach in which accident and incident data, or 'process tracing' provide experimental computational structures. Analysis of data from a simulator experiment on V/STOL zero-visibility landing performance suggests that the order of ranking of individual pilot's effectiveness varies with particular situations defined by combinations of tracking requirements (e.g., glide slope, localizer) and glide-slope segment, or speed requirements; the data are being further analyzed.

Murphy, M. R.↗

Pilot centered requirements in control/display design

A method developed for predicting pilot opinion ratings for particular vehicles and tasks using optimal control pilot model is described and an outline of a flight director design procedure based upon the optimal control pilot model is given. Longitudinal and lateral control of a helicopter in hover and in a -6 deg constant ground speed-command landing approach are considered. Emphasis is placed on display design for optimum V/STOL control.

Hess, R. A.↗

Survey of piloting factors in V/STOL aircraft with implications for flight control system design

Flight control system design factors involved for pilot workload relief are identified. Major contributors to pilot workload include configuration management and control and aircraft stability and response qualities. A digital fly by wire stability augmentation, configuration management, and configuration control system is suggested for reduction of pilot workload during takeoff, hovering, and approach.

Ringland, R. F.↗

Problems pilots face involving wind shear

Educating pilots and the aviation industry about wind shears presents a major problem associated with this meteorological phenomenon. The pilot's second most pressing problem is the need for a language to discuss wind shear encounters with other pilots so that the reaction of the aircraft to the wind shear encounter can be accurately described. Another problem is the flight director which gives a centered pitch command for a given angular displacement from the glide slope. It was suggested that they should instead be called flight path command and should not center unless the aircraft is actually correcting to the flight path.

Melvin, W. W.↗

User's manual: Subsonic/supersonic advanced panel pilot code

Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words.

Moran, J.↗

Use of piloted simulation for studies of fighter departure/spin susceptibility

The NASA-Langley Research Center has incorporated into its stall/spin research program on military airplanes the use of piloted, fixed-base simulation to complement the existing matrix of unique research testing techniques. The piloted simulations of fighter stall/departure flight dynamics are conducted on the Langley Differential Maneuvering Simulator (DMS). The paper reviews the objectives of the simulation research, presents the rationale underlying the simulation methods and procedures used in the evaluation of airplane characteristics, and discuss in detail the evaluation steps used to assess fighter stall/departure characteristics. Simulation results are presented to illustrate the flight-dynamics phenomena dealt with. The use of the piloted simulation methods and procedures described has been found very effective in identifying stability and control problem areas and in developing automatic control concepts to alleviate many of these problems. A good level of correlation between simulated flight dynamics and flight-test results has been obtained over the many fighter configurations studied in the simulator.

Gilbert, W. P.↗

Research in pilot scanning behavior

A NASA-developed oculometer, which measures pilot scanning behavior, is described in terms of design and operating parameters. Results are presented of tests conducted in a terminal configured vehicle (TVC) aft cockpit simulator, involving pilots making simulated instrument approaches. Attention is given to the amount of time the pilots spend scanning the SFD and EADI CRT displays, and to differences resulting from both the physical location of the CRTs (within a 30 x 30 x 30 cm space), and from their intrinsic characteristics.

Waller, M. C.↗

Flight experience with advanced controls and displays during piloted curved decelerating approaches in a powered-lift STOL aircraft

The control, display, and procedural features are described for a flight experiment conducted to assess the feasibility of piloted STOL approaches along predefined, steep, curved, and decelerating approach profiles. It was found to be particularly important to assist the pilot through use of the flight director computing capability with the lower frequency control-related tasks, such as those associated with monitoring and adjusting configuration trim as influenced by atmospheric effects, and preventing the system from exceeding powerplant and SAS authority limitations. Many of the technical and pilot related issues identified in the course of this flight investigation are representative of similarly demanding operational tasks that are thought to be possible only through the use of sophisticated control and display systems.

Hindson, W. S.↗

Effects of visual and motion simulation cueing systems on pilot performance during takeoffs with engine failures

Data are presented that show the effects of visual and motion during cueing on pilot performance during takeoffs with engine failures. Four groups of USAF pilots flew a simulated KC-135 using four different cueing systems. The most basic of these systems was of the instrument-only type. Visual scene simulation and/or motion simulation was added to produce the other systems. Learning curves, mean performance, and subjective data are examined. The results show that the addition of visual cueing results in significant improvement in pilot performance, but the combined use of visual and motion cueing results in far better performance.

Parris, B. L.↗

Development and validation of a piloted simulation of a helicopter and external sling load

A generalized, real time, piloted, visual simulation of a single rotor helicopter, suspension system, and external load is described and validated for the full flight envelope of the U.S. Army CH-54 helicopter and cargo container as an example. The mathematical model described uses modified nonlinear classical rotor theory for both the main rotor and tail rotor, nonlinear fuselage aerodynamics, an elastic suspension system, nonlinear load aerodynamics, and a loadground contact model. The implementation of the mathematical model on a large digital computing system is described, and validation of the simulation is discussed. The mathematical model is validated by comparing measured flight data with simulated data, by comparing linearized system matrices, eigenvalues, and eigenvectors with manufacturers' data, and by the subjective comparison of handling characteristics by experienced pilots. A visual landing display system for use in simulation which generates the pilot's forward looking real world display was examined and a special head up, down looking load/landing zone display is described.

Shaughnessy, J. D.↗