Dual TV monitor and collimated lens system in windscreens of standard aircraft cockpit simulator permits both pilot and copilot to simultaneously view three dimensional presentation. Proper design of complete system permits depth and viewpoint of visual displays to be accurately presented

Chase, W. D.

English

NASA Technical Reports Server

November 1971	 Brief 71-10427 
S
NASA TECH BRIEF 
Ames Research Center
	
_4V 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield,' Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Virtual-Image Display System for Flight Simulators 
[i
The problem: 
Conventional visual flight simulators present 
television or movie displays of outside scenes to the 
pilot only. These simulators cannot provide coordi-
nated flight training for the crews of large aircraft 
because the copilot cannot participate effectively in 
the simulation of cabin activities. Moreover, such 
displays lack the realism of actual flight, since they 
cannot provide real world visual cues with high 
fidelity, particularly for the critical aircraft takeoff 
and landing maneuvers. 
The solution: 
A dual TV monitor and collimated lens system 
in the windscreens of a standard aircraft cockpit 
simulator permits both the pilot and the copilot to 
simultaneously view the three-dimensional presenta -
tion. Proper design of the complete system permits 
the depth and viewpoint of the visual displays to be 
accurately presented. 
How it's done: 
The visual flight simulator consists of three 
groups of components: (1) an instrumented, fixed 
cockpit cabin, complete with an engine-sound sys-
tem, wheel noise, and a control system which reacts 
realistically to the pilots' movements; (2) a pair of 
projection and collimated monitor viewing systems 
which present the "outside" view to the pilots; and 
(3) a color TV camera and an optical probe which 
scans a scale model of a runway and generates for 
the TV monitor a view corresponding to the flight 
attitude of the cockpit simulator as selected by the 
pilots. 
The projection system is the conventional Schmidt 
type, with unity picture perspective magnification,
color and black-and-white viewing capability, and 
a screen brightness gain of 2.5. The pilot's eye posi-
tion for this system is located 10 ft from the screen, 
with a field of view of about 48° horizontal and 36° 
vertical and a maximum resolution of 7 min of arc. 
The collimated virtual image display system' for 
each pilot consists of a 21 in. monitor, two 25 in. 
diameter pIano-convex acrylic lenses (50 in. focal 
length), with a unity picture perspective field of view 
of 40.6° horizontal and 30.4° vertical. The colli-
mated monitor display has a maximum resolution of 
5 min of arc. Since the resolution of the human eye 
is about 1 min of arc, the TV scene lacks some of 
the detail available to a pilot in real situations. It 
was foundthat the collimated monitor scene is more 
acceptable to color TV viewing than to black and 
white TV. 
The design of'the optimum virtual-image lens sys-
tem for visual simulation displays is based on the re-
lationships among image distance, angular magnifi-
cation, field of view, and exit-window diameter. Be-
cause of sonic undesirable characteristics of refrac-
tive lens systems, a compromise had to be made in 
order to maintain height-and-depth visual cues. This 
was accomplished by minimizing observations with-
out disturbing the image area at sharp focus. 
Usually, the distance from the pilot's eye to the 
projection screen should be on the order of 10 ft. 
Calculations for the collimated monitor showed the 
best position of the image plane to be about 10.9 ft 
from the pilot's eye: therefore, 3 1/2 in. thick con-
vex lenses were selected for location in the wind-
screen area, about 27 in. from the pilot's eye. Also, 
since the TV camera's photosensitive system is nor-
mally adjusted for a field of view of about 48°. the 
This documett was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
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lens diameter was matched with the 21 in. monitor 
and selected to subtend the same field of view, thus 
preserving the linear perspective as seen by the pilot. 
The system allows pilots the freedom to move 
their heads without receiving the impression that 
the field of view has shifted grossly. Moreover, 
since sufficient collimation has been achieved, visual 
transition from the instrument panel to the dis-
played outside scene is accomplished with normal 
eye accomodation, and the altitude-range perspective 
of the display approaches that of actual flight con-
ditions. 
An analog computer was programmed to repre-
sent a 6-degrees-of-freedom simulation of a DC-8 
aircraft. The system includes longitudinal responses 
(both phugoid and short-period modes), lateral re-
sponses (including the spiral, roll subsidence, and 
Dutch-roll modes), and ground-effect character-
istics. Several hundred experimental simulated flights 
were conducted for comparison of the TV virtual-
image system with conventional TV projection 
systems, for both color and black-and-white view-
ing. Based upon the performance measures of, the 
system and on comments of commercial airline 
pilots, it was concluded that color displays wcre 
far more satisfactory than black-and-white dis-
plays. Various flight maneuvers were more accurate-
ly performed and better picture quality and depth 
perception were provided with the color monitor 
display. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: TSP7I-10427 
Patent status: 
No patent action is contemplated by NASA. 
Source: W.D. Chase
Ames Research Center
(ARC-10175)
C 
. 
. 
Brief 7 1-10427	 Category 03


Virtual-image display system for flight simulators

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