A piloted simulation study was conducted to evaluate the utility of a display device designed to illustrate graphically and conformally the approximate location of a fighter aircraft's velocity vector. The display device consisted of two vertical rows of light emitting diodes (LED's) located toward the center of the cockpit instrument panel to each side of the control stick. The light strings provided a logical extension of the head up display (HUD) velocity vector symbol at flight path angles which exceeded the HUD field-of-view. Four test subjects flew a modified F/A-18 model with this display in an air-to-air engagement task against an equally capable opponent. Their responses to a questionnaire indicated that the conformal velocity vector information could not be used during the scenarios investigated due to the inability to visually track a target and view the lights simultaneously

Burley, James R., II

Jones, Denise R.

English

NASA Technical Reports Server

NASA Technical Memorandum 102629
QUALITATIVE EVALUATION OF A CONFORMAL VELOCITY VECTOR
DISPLAY FOR USE AT HIGH ANGLES-OF-ATTACK IN FIGHTER AIRCRAFT
DENISE R. JONES
JAMES R. BURLEY II
JUNE 1990
(NA_A-F_-10752_) .._tJALITATIVL i_VALLIATIjN I-!F
A L.'_;_:,JPi,!,_.L V_Lr)CI'IV VLzfi[i!K ,..;[SPLAY l--,.}E US.'_-
AT _IGH A_C, LzS-OF-ATTACK IN FIuHI-_H, AIRCRAFT
(NASA) i1 D L;SCL Oi.r,
National Aeronautics and
Space Administration
Langley Research Center
Hampton, Virginia 23665-5225
https://ntrs.nasa.gov/search.jsp?R=19900016665 2020-03-19T22:20:53+00:00Z
SUMMARY
A piloted simulation study has been conducted in the Langley Differential
Maneuvering Simulator (DMS) to evaluate the utility of a display device designed
to illustrate graphically and conformally the approximate location of a fighter
aircraft's velocity vector. The display device consisted of two vertical rows of light-
emitting diodes (LED's) located toward the center of the cockpit instrument panel,
with one row of lights visible to the left of the control stick and the other row visible
to the right of the control stick. The light strings provided a logical extension of the
head-up display (HUD) velocity vector symbol at flight-path angles which
exceeded the HUD field-of-view. Four test subjects flew a modified F/A-18 model
with this display in an air-to-air engagement task against an equally capable
opponent. Their responses to a questionnaire indicated that the conformal
velocity vector information could not be used during the scenarios investigated
due to the inability to visually track a target and view the lights simultaneously.
INTRODUCTION
During the course of fighter aircraft display format research, many pilots have
expressed a desire to have the direction in which the aircraft is traveling (aircraft's
velocity vector) presented in the cockpit. The pilots felt that displaying the velocity
vector conformally (relative to the outside world) would be beneficial during all
phases of flight since the control systems in today's fighter aircraft are designed to
maneuver the aircraft about this vector. Thrust-vectored control systems being
developed for the next generation of fighter aircraft have accentuated this
perceived need even further as agility requirements push normal operations into
the post-stall region.
A piloted simulation study was conducted to evaluate the utility of a display device
designed to illustrate graphically and conformally the approximate location of a
fighter aircraft's velocity vector. The display device consisted of two vertical rows
of lights located toward the center of the cockpit instrument panel to each side of
the control stick. The light strings provided a logical extension of the head-up
display (HUD) velocity vector symbol at flight-path angles which exceeded the
HUD field-of-view.
This paper describes the conformal velocity vector display and experiment in
detail. Subjective results, garnered from pilot questionnaires and discussions, are
also presented.
SIMULATION CHARACTERISTICS
Aircraft Model
The aircraft simulation model utilized for this study was a non-linear, six degree-of-
freedom, rigid-body dynamic model of a F/A-18 fighter aircraft modified to include
thrust-vectoring capabilities. Thrust-vectoring enabled post-stall maneuvering of
the aircraft at angles-of-attack up to a maximum of 70 °. A description of the
modified F/A-18 aircraft model can be found in reference 1.
Simulator
This study was conducted in the Langley Differential Maneuvering Simulator
(DMS) (ref. 2, pp. 94 and 95, and ref. 3). The DMS consists of two identical fixed-
based, visual flight simulators, each housed in a 12.2 m diameter (40 ft.) projection
sphere (fig. 1). The facility was designed to provide a means of simulating two
piloted aircraft operating in a differential mode. A dynamic sky/Earth scene was
generated in each simulator sphere along with a target aircraft image. The target
image presented to each pilot represents the aircraft being flown by the pilot in the
adjacent sphere. For this study, however, only one sphere was utilized and the
target aircraft was driven by the Tactical Guidance Research and Evaluation
System (TGRES, pronounced "tigress"). TGRES is a software program that uses
knowledge-based guidance to determine the most appropriate air-combat
maneuver possible for the target aircraft relative to the position of the piloted
aircraft (refs. 1 and 4), thus providing an intelligent and equally-capable opponent.
Cockpit
The simulator cockpit utilized three color cathode ray tubes (CRT's), each with a
6.5 in. square viewing area, to display aircraft state information (fig. 2). A wide-
angle FIUD was also provided. Other controls utilized included a control stick,
dual throttles, and rudder pedals. The controls were programmed and configured
for the modified F/A-18 aircraft.
VELOCITY VECTOR DISPLAY IMPLEMENTATION
A conformal velocity vector display was implemented in the simulator cockpit to
indicate the location of the velocity vector of the aircraft. This was accomplished
by physically placing two vertical rows of light-emitting diodes (LED's) toward the
center of the cockpit instrument panel with one row of lights visible to the left of the
control stick and the other row visible to the right of the control stick (fig. 3). This
was made possible by installing the LED's in rectangular plexiglass frames. Two
rows of lights were used instead of a single row to prevent total obstruction by the
control stick while the pilot was maneuvering the simulated aircraft. The lights
positioned closest to the angular location of the velocity vector were illuminated.
The concept employed was that a straight line drawn between the pilot's eye and
the illuminated lights would form a vector parallel to the aircraft's velocity vector.
The lights were spaced in six-degree increments beginning at 16 ° at the HUD and
ending at 58 ° on the cockpit floor (fig. 4). It was thought that during an air combat
task the velocity vector lights would be seen with the pilot's peripheral vision,
therefore, the lights were flashed in order to make them more noticeable to the
pilot. Each light flashed at a 5 Hz rate, however, the light positioned at 58 ° flashed
at 10 Flz for all angles greater than 58 °. If the position of the velocity vector was
within one degree of the corresponding angular position value for a light, only that
light would be illuminated. However, when the location of the velocity vector was
between light angular position values, the two adjacent lights would be lit
accordingly. For example, if the aircraft's velocity vector was positioned at 37 ° , the
LED's located at 34 ° and 40 ° would flash simultaneously.
2
EXPERIMENT DESCRIPTION
Four pilots with varying degrees of air-combat experience participated in this
study. The pilots were asked to engage in air-to-air combat with the target aircraft.
While maneuvering against the opponent, the subjects were to evaluate the
conformal velocity vector display and determine the utility of knowing the
directional location of the velocity vector. The test was conducted on a strictly
subjective basis with a questionnaire (appendix A) being given to each pilot at the
completion of the session.
RESULTS AND DISCUSSION
This section discusses the comments obtained from the questionnaire and
observations made during the pilot sessions.
It is well known that during air-to-air combat, the most important task for the pilot is
to track the opponent visually and never lose sight of him. However, it was felt that
the conformal velocity vector lights would be seen with the peripheral vision of the
pilot and aid in engagement with an adversary. Due to the large angular
differences that occur between the two aircraft and the human field-of-view
limitations, however, it was impossible for the test subjects to see the lights during
the majority of the engagement without looking away from the opponent. This was
particularly true at high angles-of-attack when the illuminated lights were near the
floor of the cockpit. As a result, all four pilots concluded that the conformal velocity
vector display could not be utilized during the air-to-air engagement. Furthermore,
they felt that the velocity vector information was not necessary for the scenarios
utilized during this air-combat simulation, which was contrary to the information
needs perceived prior to this evaluation by the pilots and display designers alike.
The velocity vector display presented the conformal location of the velocity vector
in the vertical plane only. One pilot suggested illuminating either the right or left
row of lights to indicate the direction of sideslip. This feature would provide more
information about the vector to the pilot; however, the illuminated lights could be
obstructed by the control stick while maneuvering the aircraft.
Although the velocity vector display was not useful during the simulated air-
combat task, there may be other tasks or maneuvers, such as the "Herbst
maneuver," that could be performed more proficiently with displays of this type.
The Herbst maneuver is a 180 ° change of heading that is conducted by
manipulating the aircraft into the post-stall range and then turning as rapidly as
possible, completing the maneuver at the point of departure (ref. 5). Another
application that could possibly benefit from the velocity vector display would be
the very steep landing approaches that may be made by a Short Take-Off and
Landing (STOL) fighter. This type of landing is made at slow speeds and high
angles-of-attack, which preclude the use of a HUD since the velocity vector is
outside of the HUD field-of-view. The velocity vector display could be used to
indicate the approximate touch down point upon landing.
CONCLUDING REMARKS
Although it was thought that pilots might be able to obtain peripheral information
from a conformal presentation of the aircraft's velocity vector, this study indicated
that this was not possible during air-to-air engagements. The test subjects could
not see the lights while visually tracking a target due to the large angular
differences that occur between the two aircraft and the human field-of-view
limitations. Although this implementation of a conformal velocity vector display
was not advantageous for the scenarios investigated in this simulated air-combat
environment, there may be other tasks that could benefit from this type of
information display.
4
APPENDIX A
Velocity Vector Lights Display Questionnaire
The simulated flight that you've just completed incorporated a set of lights in the
cockpit which indicated the spatial location of the velocity vector at high angles-of-
attack. Please answer the following questions regarding the utility of this display
concept.
1. Did you find the velocity vector lights useful under any of the simulated flight
conditions? If so, which flight conditions and how were they useful?
. Are there any other flight tasks that you can think of in which the velocity vector
lights would be useful? If so, how would the lights be used to accomplish the
task that you've just described?
3. How would you change the velocity vector lights to make them more useful to
you?
4. Looking back over your answers, what would you conclude about the
usefulness of the velocity vector lights and why?
Thank you for your time and comments. Hopefully, your efforts will lead us to a
better understanding of the pilot's needs in tomorrow's high performance aircraft.
If you are interested in the final results of tl_is test, please leave your name and
address so that I can mail you a copy of the results.
5
REFERENCES
° Goodrich, Kenneth H.; and McManus, John W.: Development of a Tactical
Guidance Research and Evaluation System (TGRES). AIAA Flight
Simulation Technologies Conference, Paper No. 89-3312, August 14-16,
1989.
2. Langley Aerospace Test Highlights - 1988. NASA TM-101579, May 1989.
o Ashworth, B. R.; and Kahlbaum, William M., Jr.: Description and Performance
of the Langley Differential Maneuvering Simulator. NASA TN D-7304,
June 1973.
° McManus, John W.; and Goodrich, Kenneth H.: Application of Artificial
Intelligence (AI) Programming Techniques to Tactical Guidance for Fighter
Aircraft. AIAA Guidance, Navigation, and Control Conference, Paper No. 89-
3525, August 14-16, 1989.
5. Herbst, W. B.: Supermaneuverability. Jahrestagung 1983der Deutschen
Gesellschaft fur Luft- und Raumfahrt, Paper No. 83-106, October 17-19, 1983.
6
L-71-8700
Figure 1. Artist rendition of the Differential Maneuvering Simulator.
\
L-86-7487
Figure 2. DMS instrument panel.
ORrG[NAL PAGE
BLACK AND WHITE PHOTOGP,,A,pH
7
8Figure 3.
L-89-8041
DMS cockpit emphasizing velocity vector lights.
ORIGINAL PAGE
BLACK AND WHITE PHOTOGRAPH
CAT
Display/
/
,///_vVee locity A
ctor
Lights
 YYYA
I-d
0
0
0
0
0
0
0
0
0
0
HUD
16o --
22o I
Figure 4. Angular position of velocity vector lights.
Report Documentation Page
I 1. Report No
NASA TH-102629
2 Government Accession No
4 Title and Subtitle
Qualitative Evaluation of a Conformal Velocity Vector
Display for Use at High Angles-of-Attack in Fighter
Aircraft
7 Author(s)
Denise R. Jones
James R. Burley It
9. Performing Orgamzat_on Name and Address
NASA-Langley Research Center
Hc:mpton, VA 23665-5225
12 Sponsonng Agency Name and Address
National Aeronautics and Space Administration
Washington, DC 20546-0001
3 Rec_p_ent's Catalog No
_- 5 Report Date
June 1990
6 Performing Organ_zabon CodeI
8 Performing Organtzatton Report No
10 Work Unit No.
505-66-71
11. Contract or Grant No
13 Type of Report and Period Covered
Technical Memorandum
14 Sponsor,ng Agency Code
15 Supplementary Notes
16. Abstract
A piloted simulation study has been conducted to evaluate the utility of a display device designed to
illustrate graphically and conformally the approximate location of a fighter aircraft's velocity vector. The
display device consisted of two vertical rows of light-emitting diodes (LED's) located toward the center
of the cockpit instrument panel to each side of the control stick. The light strings provided a logical
extension of the head-up display (HUD) velocity vector symbol at flight-path angles which exceeded the
HUD field-of-view. Four test subjects flew a modified F/A-18 model with this display in an air-to-air
engagement task against an equally capable opponent. Their responses to a questionnaire indicated
that the conformal velocity vector information could not be used during the scenarios investigated due
to the inability to visually track a target and view the lights simultaneously.
17 Key Words (Suggested by Author(s))
Fighter Aircraft
High Angle-of-Attack
Display Systems
Man-Machine Systems
Aircraft Instrumentation
19. Securrty Classff. (of this report)
Unclassified
[ 18 DJstrtbuhon Statement
Unclassified-Unlimited
Subject Category 06
20. Security Classif (of this page)
Unclassified
21 No of pages 22. Price
A02
NASA FORM 1626 OCT 86


Qualitative evaluation of a conformal velocity vector display for use at high angles-of-attack in fighter aircraft

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