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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Analysis of a longitudinal pilot-induced oscillation experienced on the approach and landing test of the space shuttle

During the final free flight (FF-5) of the shuttle's approach and landing tests, the vehicle experienced pilot-induced oscillations near touchdown. The light test data showed that pilot inputs to the hand controller reached peak-to-peak amplitudes of 20 deg at a frequency between 3 and 3.5 radians per second. The controller inputs were sufficient to exceed the priority rate limit set in the pitch axis. A nonlinear analytical study was conducted to investigate the combined effects of pilot input, rate limiting, and time delays. The frequency response of the total system is presented parametrically as a function of the three variables. In general, with no dead time, for controller inputs of 5 deg or less, the total system behaves in a linear fashion. For 10 deg of controller input, independent of the delay time, the elevon loop will be rate saturated above a frequency of 4 radians per second.

Smith, J. W.↗
NASA NTRS1982

In-flight investigation of the effects of pilot location and control system design on airplane flying qualities for approach and landing

The handling qualities of large airplanes in the approach and landing flight phase were studied. The primary variables were relative pilot position with respect to center of rotation, command path time delays and phase shifts, augmentation schemes and levels of augmentation. It is indicated that the approach and landing task with large airplanes is a low bandwidth task. Low equivalent short period frequencies and relatively long time delays are tolerated only when the pilot is located at considerable distance forward of the center of rotation. The control problem experienced by the pilots, when seated behind the center of rotation, tended to occur at low altitude when they were using visual cues of rate of sink and altitude. A direct lift controller improved final flight path control of the shuttle like configurations.

Weingarten, N. C.↗
NASA NTRS1982

An experimental study of human pilot's scanning behavior

The scanning behavior and the control behavior of the pilot who manually controls the two-variable system, which is the most basic one of multi-variable systems are investigated. Two control tasks which simulate the actual airplane attitude and airspeed control were set up. In order to simulate the change of the situation where the pilot is placed, such as changes of flight phase, mission and others, the subject was requested to vary the weightings, as his control strategy, upon each task. Changes of human control dynamics and his canning properties caused by the modification of the situation were investigated. By making use of the experimental results, the optimal model of the control behavior and the scanning behavior of the pilot in the two-variable system is proposed from the standpoint of making the performance index minimal.

Washizu, K.↗
NASA NTRS1982

Modeling lateral acceleration effects on pilot performance

Attendant to the direct side force maneuver of a Vectored Force Fighter is the transverse acceleration imposed on the pilot. This lateral acceleration (Gy), when combind with a positive Gz stress, is a potential source of pilot tracking performance impairment. A research effort to investigate these performance decrements includes experimental as well as anaytical pilot performance modeling using the Optimal Control Model.

Korn, J.↗
NASA NTRS1981

The integration of control and display concepts for improved pilot situational awareness

Consideration is given to a part of the Langley Terminal Configured Vehicle program in which the pilot is retained as an active segment of an integrated system. The pilot is active in the outer control loop and controls the orientation of the aircraft velocity. The pilot thus has a task, but a low workload. Attention is also given to first- and second-generation primary flight display for horizontal and vertical situation awareness.

Person, L. H., Jr.↗
NASA NTRS1982

Visual scanning behavior and mental workload in aircraft pilots

This paper describes an experimental paradigm and a set of preliminary results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary as a function of the level of difficulty of a verbal loading task. The average dwell time of each fixation on the pilot's primary instrument increased as a function of the loading. The scanning behavior was also a function of the estimated skill level of the pilots, with novices being affected by the loading task much more than experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

Tole, J. R.↗
NASA NTRS1980

Instrument scan - Is it an indicator of the pilot's workload

Results of an investigation of the relationship between an aircraft pilot's visual scanning of instruments and the level of mental activity during a simulated approach and landing are presented. Noting that periods of activity which demand either close to 100% of human capacity or low levels of capacity are the times when most errors are committed, trials were conducted with three NASA test pilots in a terminal configured vehicle simulator. The pilots flew a normal approach while verbally responding to three digit stimuli to be judged plus or minus according to an order of magnitude scheme, and also while using a control stick to extinguish a light that came on and off to the right and left of the instrument panel. Eyescans of the instrumentation were monitored, and determinations were made of the most common instruments used during approach and flare. Fixation on instruments was found to increase with the arithmetic tasks.

Ephrath, A. R.↗
NASA NTRS1983

Comparative evaluation of workload estimation techniques in piloting tasks

Techniques to measure operator workload in a wide range of situations and tasks were examined. The sensitivity and intrusion of a wide variety of workload assessment techniques in simulated piloting tasks were investigated. Four different piloting tasks, psychomotor, perceptual, mediational, and communication aspects of piloting behavior were selected. Techniques to determine relative sensitivity and intrusion were applied. Sensitivity is the relative ability of a workload estimation technique to discriminate statistically significant differences in operator loading. High sensitivity requires discriminable changes in score means as a function of load level and low variation of the scores about the means. Intrusion is an undesirable change in the task for which workload is measured, resulting from the introduction of the workload estimation technique or apparatus.

Wierwille, W. W.↗
NASA NTRS1981

Visual scanning behavior and pilot workload

An experimental paradigm and a set of results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary as a function of the level of difficulty of a verbal mental loading task. The average dwell time of each fixation on the pilot's primary instrument increased as a function of the estimated skill level of the pilots, with novices being affected by the loading task much more than the experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

Harris, R. L., Sr.↗
NASA NTRS1983

Analysis of pilot control strategy

Methods for nonintrusive identification of pilot control strategy and task execution dynamics are presented along with examples based on flight data. The specific analysis technique is Nonintrusive Parameter Identification Procedure (NIPIP), which is described in a companion user's guide (NASA CR-170398). Quantification of pilot control strategy and task execution dynamics is discussed in general terms followed by a more detailed description of how NIPIP can be applied. The examples are based on flight data obtained from the NASA F-8 digital fly by wire airplane. These examples involve various piloting tasks and control axes as well as a demonstration of how the dynamics of the aircraft itself are identified using NIPIP. Application of NIPIP to the AFTI/F-16 flight test program is discussed. Recommendations are made for flight test applications in general and refinement of NIPIP to include interactive computer graphics.

Heffley, R. K.↗
NASA NTRS1983

Visual scanning behavior and pilot workload

Sophisticated man machine interaction often requires the human operator to perform a stereotyped scan of various instruments in order to monitor and/or control a system. For situations in which this type of stereotyped behavior exists, such as certain phases of instrument flight, scan pattern was shown to be altered by the imposition of simultaneous verbal tasks. A study designed to examine the relationship between pilot visual scan of instruments and mental workload is described. It was found that a verbal loading task of varying difficulty causes pilots to stare at the primary instrument as the difficulty increases and to shed looks at instruments of less importance. The verbal loading task also affected the rank ordering of scanning sequences. By examining the behavior of pilots with widely varying skill levels, it was suggested that these effects occur most strongly at lower skill levels and are less apparent at high skill levels. A graphical interpretation of the hypothetical relationship between skill, workload, and performance is introduced and modelling results are presented to support this interpretation.

Tole, J. R.↗
NASA NTRS1982

Visual scanning behavior and pilot workload

This paper describes an experimental paradigm and a set of results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary with the difficulty of a verbal mental loading task. The average dwell time of each fixation on the pilot's primary instrument increased with the estimated skill level of the pilots, with novices being affected by the loading task much more than experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

Harris, R. L., Sr.↗
NASA NTRS1982

Entropy, instrument scan, and pilot workload

Experimental results are presented from a set of experiments designed to explore the relationship between the performance, skill, and visual scanning behavior of pilots under varying levels of mental workload. Instrument fixations were recorded as groups of pilots with widely differing levels of skill simultaneously performed a continuous instrument flight task and a verbally presented loading task with four discrete levels. Pilot scanning patterns were found to be significantly affected by the level of mental workload in a manner that was dependent on skill. These scanning alterations were quantified by the methods of entropy and autocorrelation, where the former concerns visual scan path and the latter assesses the relations among scan periodicity, skill level and mental task periodicity.

Tole, J. R.↗
NASA NTRS1983

Single pilot IFR accident data analysis

The aircraft accident data recorded by the National Transportation and Safety Board (NTSR) for 1964-1979 were analyzed to determine what problems exist in the general aviation (GA) single pilot instrument flight rule (SPIFR) environment. A previous study conducted in 1978 for the years 1964-1975 provided a basis for comparison. This effort was generally limited to SPIFR pilot error landing phase accidents but includes some SPIFR takeoff and enroute accident analysis as well as some dual pilot IFR accident analysis for comparison. Analysis was performed for 554 accidents of which 39% (216) occurred during the years 1976-1979.

Harris, D. F.↗
NASA NTRS1983

Pilot controls and SPIRF flight

A study was performed to determine the relative advantages and disadvantages of four candidate pilot control devices for use by a single pilot flying a general aviation aircraft in instrument meteorological conditions. Only the pitch and roll axes were considered. The control devices examined were the wheel-yoke, center-stick, Brolley handles, and side-arm controller. Qualitative evaluation criteria were established that included instrument panel visibility, control sensitivity, pilot comfort, and space requirement behind the instrument panel. The results of the study indicated that the side-arm controller offered the possibility of an improvement, but further research was necessary to determine its feasibility.

Downing, D. R.↗
NASA NTRS1983

A flight investigation of simulated data link communications during single-pilot IFR flight

A Flight Data Console (FDC) was developed to allow simulation of a digital communications link to replace the current voice communication system used in air traffic control (ATC). The voice system requires manipulation of radio equipment, read-back of clearances, and mental storage of critical information items, all contributing to high workload, particularly during single-pilot operations. This was an inflight study to determine how a digital communications system might reduce cockpit workload, improve flight proficiency, and be accepted by general aviation pilots. Results show that instrument flight, including approach and landing, can be accomplished quite effectively using a digital data link system for ATC communications. All pilots expressed a need for a back-up voice channel. When included, this channel was used sparingly and principally to confirm any item of information about which there might be uncertainty.

Parker, J. F.↗
NASA NTRS1984

Real-time pilot guidance system for improved flight test maneuvers

The Dryden Flight Research Facility of the NASA Ames Research Center has developed a pilot trajectory guidance system that increases the accuracy of flight-test data and decreases the time required to achieve and maintain desired test conditions. The system usually presented to the pilot computed differences between reference or desired and actual flight state conditions. The pilot then used a cockpit display as an aid to acquire and hold desired test conditions. This paper discusses various flight-test maneuvers and the quality of data obtained using the guidance system. Some comparisons are made between the quality of maneuvers obtained with and without the system. Limited details of the guidance system and algorithms used are included. In general, the guidance system improved the quality of the maneuvers and trajectories flown, as well as allowing trajectories to be flown that would not have been possible without the system. This system has moved from the developmental stage to full operational use in various Dryden research and test aircraft.

Meyer, R. R., Jr.↗
NASA NTRS1983

Real-time pilot guidance system for improved flight-test maneuvers

The Dryden Flight Research Facility has developed a pilot trajectory guidance system that is intended to increase the accuracy of flight-test data and decrease the time required to achieve and maintain desired test conditions, or both. The system usually presented to the pilot computed differences between reference or desired and actual flight state conditions. The pilot then used a cockpit display as an aid to acquire and hold desired test conditions. This paper discusses various flight-test maneuvers and the quality of data obtained using the guidance system. Some comparisons are made between the quality of maneuvers obtained with and without the system. Limited details of the guidance system and algorithms used are included. In general, the guidance system improved the quality of the maneuvers and trajectories flown, as well as allowing trajectories to be flown that would not have been possible without the system. This system has moved from the developmental stage to full operational use in various Dryden research and test aircraft.

Meyer, R. R., Jr.↗