Suchergebnisse

This study investigated the problem of navigation in low-altitude, high-speed, terrain-following flight. Tests were made in a four-degree-of-freedom flight simulator that had an out-of-cockpit television presentation synchronized with it in such a way that a subject seemed to be flying over a landscape with freedom to climb, descend, and change course at will. Twelve experienced jet pilots flew 48 one-and-one-half-hour missions using several combinations of navigational and terrain-following displays in two different types of simulated aircraft. The results showed that the pilots navigated with much greater efficiency when they had information from a simulated inertial guidance system than when they did not have this information. They navigated better in mountainous terrain when they used a head-up display for terrain-following than when they used conventional in-cockpit instruments for terrain-following, and they navigated better in the aircraft that had the more desirable handling qualities.

To assure maximum effectiveness, digital system design parameters must be chosen to optimize human perception. An experimental methodology is described which relates human visual performance and electronic design parameters. These relationships are then used to show how to specify optimal encoder design parameters. To illustrate this experimental procedure, tradeoffs were determined for a digitally encoded television system. These relationships were determined by measuring subjects' minimum perceptible acuities for various length lines and spatial orientations. Visual performance was determined for points along four noise-bandwidth curves representing different information capacities and system costs. Optimum system performance was achieved by maximizing the sampling frequency (bandwidth) of the encoder.

Digital communication systems distort their signals as a consequence of the digitization process. The distortions are related to the code length and sampling frequency of the system. The present study assessed viewers' responses to these variables by using simulated digital television. To do this, 24 subjects rated the quality of pictures distorted by several combinations of the variables. A response surface generated from the ratings showed that the ratings were affected by both variables, but most profoundly by code length. Interpretation of the surface's contours from the perspective of system costs revealed that costs should be considered solely from the standpoint of code length.

Pilots were task-loaded to various degrees in simulated low-altitude, high-speed flight. Approximately 210 hours of flight were made in a moving-base simulator that had a total vertical travel of 12 feet and an acceleration capability of ±6G. A jet aircraft in the light fighter or attack category was mechanized on the simulator's analog computer. Flights were made over several types of terrain at several airspeeds under different conditions of navigation task and emergency task loading. Medium-heavy turbulence was simulated for the flights, each of which lasted one hour. Performance deteriorated markedly as terrain slopes increased in steepness and as airspeed increased from .4 Mach and .7 Mach to .9 Mach. Navigation and emergency task performance did not vary with any of the experimental conditions, and did not affect the pilots' ability to maintain a 500 foot terrain clearance. There was no evidence of fatigue during the flights.

A head-up display (HUD) was evaluated in simulated low-altitude high-speed terrain-following flight using a four degree of freedom moving-base simulator. An aircraft representative of the RF-4C was programmed as the test vehicle through analog computers associated with the simulator. Six Air Force pilots made a total of 108 one-half hour flights in various terrain, airspeed, and visibility conditions. The pilots' tasks during the flights were to maintain a given clearance altitude and heading at all times. The results showed that terrain-following with the HUD was better than it was with typical in-cockpit instruments. The pilots also preferred the HUD to the in-cockpit instruments, although they felt that numerous improvements could be made to the particular HUD that was used. General findings were that terrain-following efficiency varied with type of terrain, airspeed, and visibility.

Responses of experienced pilots and aerial observers were studied in simulated low-altitude, high-speed (LAHS) flight. The pilots "flew" three-hour surveillance missions at airspeeds of .4M and .9M in different degrees of simulated atmospheric turbulence. Flying ability decreased from .4 to .9M; however, intensity of vertical accelerations did not seem to affect flying ability except at the most severe levels. Target identification was unimpaired by either turbulence or airspeed. The observers also flew three-hour missions while experiencing acceleration time histories recorded from the pilot's flights. Target identification deteriorated as airspeed increased from 0.4 to 0.9 Mach. Gust intensity did not affect performance of any of their tasks. Performance efficiency on all tasks did not deteriorate from beginning to end of the missions of both pilots and observers.