The setup, validation, and results of the Rotor Systems Research Aircraft (RSRA) fixed-wing, moving-base simulation performed in May 1983 are covered. The emphasis of the simulation was to familiarize the pilots with the RSRA's fixed-wing configuration. Additional information concerning stall speeds, minimum control speed, and various gross weights were recorded and included in the report

Kufeld, R. M.

English

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NASA Technical Memorandum 85863
NASA-TM-85863 19840005108
Rotor Systems Research Aircraft:
Fixed-Wing Simulations Results
Robert M. Kufeld
LIBRARY COpy
! I
December 1983
NI\S/\
National Aeronautics and
Space Administration
" ';' '984
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LANGLEY. RESEARf:H CENTER
LIBRARY, NASA
HAMPTON, VIRGINIA
https://ntrs.nasa.gov/search.jsp?R=19840005108 2020-03-21T01:54:04+00:00Z

2 1 RN/NASA-TM-85863
RPT#: NASA-TM-85863
01 SPLA\=' (i2/'-6../ '1 ':
84N13176** ISSUE 4 PAGE ~83 CATEGORY 5
83/12/00 16 PAGES UNCLASSIFIED DOCUMENT
UTTL: Rotor sYstems research ct\fCttift: Fixed-wing simuldt\o~S results
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;*COMPUTERIZEO SIMULATIO~l/*FIXEO WINGS/*ROTOR SYSTEMS RESEARCH AIRCRAFT
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NASA Technical Memorandum 85863
Rotor Systems Research Aircraft:
Fixed-Wing Simulations Results
Robert M. Kufeld, Ames Research Center, Moffett Field, California
NI\S/\
National Aeronautics and
Space Administration
Ames Research Center
Moffett Field, California 94035
N'tL/- J317(p~

SUMMARY
This report covers the setup, validation, and results of the Rotor Systems
Research Aircraft (RSRA) fixed-wing, moving-base simulation performed in May 1983.
The emphasis of the simulation was to familiarize the pilots with the RSRA's fixed-
wing configuration, which has never been flown. Additional information concerning
stall speeds, minimum control speed, and various gross weights were recorded and
included in the report.
INTRODUCTION
The Rotor Systems Research Aircraft (RSRA) (ref. 1), a test bed for advanced
rotor systems, is capable of flying in three different modes: helicopter, fixed-
wing, and compound (fig. 1). The RSRA also has a variable incidence wing that adds
an additional degree of configuration variability to the fixed-wing and compound
modes. Before the planned tests of the fixed-wing flight envelope, a moving-base
simulation was performed. The purpose of this simulation was to familiarize the
project pilots with the low-speed and high-speed handling qualities of the fixed-wing
aircraft in its various flying configurations, to develop a preferred takeoff and
landing technique, and to determine the fixed-wing stall speeds. The various flying
configurations included in the simulation were: wing incidences from 0° to 15°, tail
rotor on/off, vertical center of mass from water line 222 to water line 230, gross
weights from 11,864 kg (26,100 lb) to 15,000 kg (33,000 lb), and control phasing
unit (CPU) changes from 100% to 50% control authority in the pitch axis.
SIMULATION
Setup
The simulation was performed on the 6-degree-of-freedom Flight Simulator for
Advanced Aircraft (FSAA) at NASA Ames Research Center (ref. 2). The mathematical
model (ref. 3) used in the simulation is a modular form capable of simulating any of
three RSRA modes. The equations of motion are solved interactively by summing the
forces and moments of each module. The resulting aircraft motion is then transferred
into the Earth inertial-frame axis to provide proper simulator motion. The mathemat-·
ical model and cockpit configuration used in this simulation were previously devel-
oped and used successfully prior to this simulation project; therefore, further
development was unnecessary. The cockpit was configured with the following instru-
ments and controls:
Controls
Collective stick
Cyclic stick
Rudder pedals (with toe brakes)
Flap handle
TF-34 engine throttles
Validation
Instruments
Rate-of-climb indicator
Side-slip indicator
Wing angle of attack
TF-34 fan speed
T-58 torque
Rotor rpm
Turn and slip indicator
Airspeed indicator
A static comparison of the mathematical model to actual flight data was per-
formed to provide confidence in the results of the simulation. The static flight
data were accumulated from compound flights 740-2B-14 and 740-2B-16 (ref. 4). Com-
parison was made of the compound mode only; fixed-wing flight data were nonexistent.
Results of the static comparison are shown in figures 2-4. These plots show good
agreement between flight and simulator data. The minor discrepancy shown in the
lateral stick position and wing angle of attack can be attributed to known source
of error. The error in lateral stick position occurs because the roll degree of
freedom was eliminated from the simulation model for the static comparison. The
discrepancy between simulator and flight wing-angle-of-attack data can be attributed
to the error in the wing-angle-of-attack measurement, which occurred because the
measurement was made in the induced flow of the wing.
Results
Takeoff- Various takeoff configurations were simulated to obtain a preferred
takeoff configuration and technique for future fixed-wing flights. The pilots
preferred a takeoff configuration of 50 wing incidence with flaps down. The tech-
nique used for takeoff is as follows: a full-power acceleration to takeoff speed,
a small longitudinal stick displacement forward to lift the tail wheel off the
ground at 60 knots, and continued to acceleration until the main wheels lift off the
ground at aboutl20 knots. The lift-off required slight aft stick displacement. The
three-point takeoff technique, where all three wheels lift off at the same time,
was determined to be unacceptable because of a rapid pitch up of the aircraft at
lift-off .
The directional control stability of the fixed-wing configuration during take-
off roll was also studied. It was concluded that the simulation's landing gear
model could not adequately simulate the landing gear reactions, and the question of
directional control stability on the ground remains unanswered. Further investiga-
tion during the high-speed taxi test will be required.
The control power of the tail rotor and vertical tail during the low-speed
takeoff roll was studied. The "tail rotor on" configuration provided excellent
directional control at low speeds. In the "tail rotor off" configuration, which
was considered the worst-case situation, the pilots noticed that the rudder became
effective at approximately 60 knots. Below 60 knots, differential brakes were used
for directional control. Again, the runway interaction model makes these results
questionable.
2
Landing- The landing configuration and technique described below were chosen by
the pilots because they provided the lowestworkloCld and a comfortable pitch atti-
tude during landing. A landing pitch attittide'less than the RSRA's ground angle of
2° was desired by the pilots to avoid tail wheel first landings; The configuration
had a 5° wing incidence and the flaps were full down. 'Table 1 gives the other land-
ing configurations and attitudes that were simulated. The landing technique devel-
oped in the simulation starts with an approach speed of 140 knots, flaps down, and
a rate of descent of 0.305 km/min (1,000 ft/min). Once over the runway, a rotation
is made to the landing attitude, decreasing power to slow down and to maintain a
rate of descent. The touchdown velocity was around 125 knots, which is Over
1.1 times the flaps-down stall speed (Vsf). The same technique is used with flaps
up, except that the approach speed was 160 knots and touchdown was approximately
145 knots. Although the 5° wing incidence, full flaps configuration provided the
lowest pilot workload during landing, the landing was still a very high workload
condition. The simulation shows a tendency for the aircraft to climb upon the rota-
tion to landing attitudes, and requires quite a bit of finesse to coordinate the
power reduction with the rotation to maintain a rate of descent.
The landing simulation was also used to verify the response of the aircraft to
a go-around situation and to landing with a crosswind. The go-around situation
showed that the aircraft could be easily controlled during a sudden increase to full
power. The crosswind landing showed that the aircraft responded as expected; accept-
able landings were made with a 10-knot crosswind. Higher crosswind landings were not
attempted. Again, conclusions drawn during the landing rollout are questionable.
StallB- The response of the aircraft at high angles of attack in various con-
figurations was also simulated. The power-on stall speeds and wing angles of attack
for the different configurations are listed in Table 2. The aircraft showed no
roll-off tendency in stall in any configuration except with 15° wing incidence and
flaps full down. The stall in the simulation was distinguishable by the aircraft's
ina6ility to maintain level flight followed by a sharp rise in angle of attack and
rate of descent. Lateral maneuvers were made in the stalled flight condition to
confirm that the lateral controllability of the aircraft at high angles of attack
was acceptable. There was no perceivable difference in stall characteristics with
or without tail rotor.
Engine out- Single-engine failures in flight, single-engine-out landings, and
the determination of minimum control speed (Vmc ) were simulated in different con-
figurations. The response of the aircraft to an engine failure in flight was a
slight yaw in the direction of the failed engine, a decrease in airspeed, and a
slight descent. This motion was easily controlled by the pilot. The simulation of
engine-out landings provIded acceptable aircraft response to the pilots. However,
go-arounds from a landing attitude were marginal. The maximum rate of climb that
was obtained in the simulation with wing incidence at 5° and flaps full down was
0.076 km/min (250 ft/min) at an airspeed of 125 knots. The low rate of climb coupled
with an airspeed near flaps-up stall speed creates a high pilot workload.
The minimum control speed (Vmc ) was determined in two different configurations:
wing incidence 7.5°, full flaps and wing incidence 10°, full flaps. The minimum
control speed is defined as the airspeed which requires 90% of the pedal deflection
tq overcome the asymmetrical thrust caused by an engine-out condition. The minimum
control speed for 7.5° wing incidence, full flaps was 104 knots and ~nc for 10°
wing incidence, full flaps was 106 knots.
3
High speed- Airspeeds up to 250 knots were flown in the simulator~ where the
control response of the aircraft was studied by the pilot. The only configuration
change at these high speeds was moving the CPU from 100% fixed-wing pitch control
to 50% fixed-wing pitch control. The pilot favored the 100% CPU position because
of the increased control sensitivity. The pilot also reported no tendency for
pilot-induced oscillation reported in previous simulations (ref. 5).
Weight and vertical center of mass- Small deviations from the normal flight
configuration were simulated to give the pilots some experience with different
weights and center of mass (CM) of the aircraft. The gross weights used were
ll~834~ l2~727~ l3~636~ and l5~000 kg (26~lOO~ 28~000~ 30~OOO~ and 33~OOO lb). The
expected fixed-wing gross weight of ll~834 kg (26~100 lb) was the normal weight
used in the simulation. Takeoffs and landings were simulated at each of these
weights~ and the response of the aircraft~ as noted by the pilot~ became increas-
ingly more sluggish as the weight increased.
The CM of the aircraft was raised from its normal fixed-wing waterline posi-
tion of 222 to a waterline of 230. This configuration was simulated because of a
planned high vertical CM test. Again~ takeoffs and landings were simulated~ gener-
ating a similar response from the pilot; the new configuration was more sluggish
than the nominal configuration. In all of the cases~ however~ the aircraft had
acceptable handling qualities.
CONCLUSIONS
The RSRA fixed-wing simulation provided important information in preparation
for the fixed-wing flight test. Takeoff and landing techniques were developed.
The pilots became familiar with the low-speed~ high-speed~ and engine-out flying
qualities of the aircraft. The sensitivity of the aircraft to changes to CM and
gross weight was also explored.
The simulation was unable to supply useful information about directional con-
trol of the aircraft during takeoff roll but did provide information about tail
rotor on/off control power. It is believed that the landing-gear mathematical
model could be improved to provide directional control information and should be
studied at a later time.
The simulation validation showed good comparison between flight and simulation
data. A comparison of dynamic flight data with simulation data is presently being
accomplished and will be discussed in a later report.
4
REFERENCES
1. Linden, A. W.; and Hellyar, M. V.: The Rotor Systems Research Aircraft - A
Flying Wind Tunnel. AIAA Paper 74-1277, Toronto, Ontario, Canada, 1974.
2. Sinacori, J. B.; Stapleford, R. L.; Jewell, W. F.; and Lebman, J. M.:
Researchers Guide to the NASA Ames Flight Simulator for Advanced Aircraft.
NASA CR-2875, 1977.
3. Houck, J. A.; Moore, F. L.; Howlett, J. J.; Rellock, K. S.; and Browne, M. M.:
Rotor System Research Aircraft Simulation Mathematical Model. NASA
TM-78629, Nov. 1977.
4. Erickson, R. E.; Kufeld, R. M.; Cross, J. L.; Hodge, R. W.; Ericson, W. F.;
and Carter, R. D. G.: RSRA 740 Flight Test Data Report Helicopter and
Compound Configuration. NASA TM-85843, Sept. 1983.
5. Nguyen, S. T.: Results of Simulation of RSRA in DMS Facility. Memorandum to
RSRA Project Office, June 5, 1975. (Available from the Rotorsystems Flight
Investigations Branch, Moffett Field, California.)
5
TABLE 1.- LANDING CONFIGURATION
Wing Approach LandingFlaps pitch pitchincidence, position altitude, attitude,deg deg deg
0 UP +4 9
0 DOWN -1.5 5
5 UP 0 3.5
5 DOWN -4.5 2
7.5 UP -1.5 3
7.5 DOWN -5 0
10 UP -3.5 2
'10 DOWN -8 -1
15 UP -7.6 0
15 DOWN -10.6 -4
TABLE 2.- SIMULATION STALL SPEEDS
Wing StallWing Flaps angle of a
incidence position attack, speed,
deg knot
0 UP 18 121
0 DOWN 16 99
7.5 UP 18 125
7.5 DOWN 16 100
10 UP 18 127
10 DOWN 17 101
15 UP 18 130
15 DOWN 17 107
aStall speed data taken in true
airspeed.
6
HELICOPTER
AIRPLANE
COMPOUND
Figure 1.- Simulations of RSRA helicopter, airplane, and compound modes.
7
WING INCIDENCE Iw =10
0
COLLECTIVE STICK Xc =40%
<> FLIGHT 14
'\l FLIGHT 16
• SIMULATION RESULTS, 5-83
•
10
N UP
5
o
NON
-51....-__....1. ..... "--__....1. -'
50
AFT
40
30
FWD
201....-__....1. ..... "--__....1. -'
50
UP
40
30
ON20 I....-__--L ...I..-__....... ..I.-__----"
15
N UP
10
5
NON01....-__....1. ..... "--__--&. -'
10
N UP
5
180100 120 140 160
CALIBRATED AIRSPEED, knots
o
N ON L__L-_~~~~~~~---l
-5
80
(a) Longitudinal comparisons~
Figure 2.- RSRA trim level flight; collective stick = 40%.
8
WING INCIDENCE Iw = 10°
COLLECTIVE STICK Xc =40%
o FLIGHT 14
'V FLIGHT 16
• SIMULATION RESULTS, 5-83 .
-~- ~.' -', " , ' .
. .'
Cl
Q)
"C
0.'
...J(I)
W 0
o LT.(I) -5 L-__....;.L ...l- .L.-__--L__---J
6
RT.4 .......__......L. .L...-__--L ..L-__.....J
10
LT.
8 <> A.~.~__. ..:~~ v.
_~:M:-.-~<>4,.,V~
• • • •50
LT.
40 .......__--L-__--'----J....---...L---.....J
70
RT.
60
...J
<!~0 0 ,Wz
0.0
a:-
w!::
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00
::::>0.
a:
g 5
"C, RT.
...JW 0
...JO
0:::>
a:!:: -5
l-I- LT.
<! -10 '--__......L. ...L..-__--L ...L...__.....J
180
••••
100 120 140 160
. CALIBRATED AIRSPEED, knots
60
*...J ,RT.<! ~z 50
a:u O
w-i=
1-1- - 40<!(I)(I)
...J 2 LT.
30 '--__---L -l.-_.,.".,..;-_~__---L ...I
80
(b) Lateral comparisons.
Figure 2.- Concluded.
9
WING INCIDENCE Iw =10°
COLLECTIVE STICK Xc =35%
o FLIGHT 14
V FLIGHT 16
• SIMULATION RESULTS, 5-83
10
N UP
5
o • () --o.~
NON • yv
-5 '--__--1- .... .......__....... -'
30
FWD20 L-.__........__---JI.--__....L-__---L__---'
50
AFT
40 •
50
UP
40
· -o--.....<:>---4-<>~
30
ON20 '--__......... ..&.-__--L. ........__----'
5
NONOL..-__--'- .L.-__--L ...!-__---J
•
•
•
15
N UP
10
180
10
N UP
5
o ·""O A
N ON -V~__o_ sf.i.ri-
-5 L..-__--'- .L.-__--L__-...!------J
M 100 1~ 1~ 100
CALIBRATED AIRSPEED, knots
(a) Longitudinal comparisons.
Figure 3.- RSRA trim level flight; collective stick = 35%.
10
WING INCIDENCE Iw =,10° ','
COLLECTIVE STICK Xc·~ 35,%
o FLIGHT 14
V FLIGHT 16
• SIMULATLON RESULTS, 5-83
•-I.'o::---~~---f4J-­v .v-~ •
••
• O·__O~·' ~
• 0
•
.~
..¢
•
-o-~--o~
• • V V~~
•
-0-
.-0
100 120 140 160 180
CALIBRATED AIRSPEED, knots
C'I 10
CI) RT."'C
Q.' 5
...J
(I)
W 00 LT.(I)
-5
0: 0 C'I
10
OWCl) LT.1-(1)"0 80(1) ,
o:w::r:
...Jo:u 6_0..1-«~c::: RT.1-- 4
...J 70«~o Q, RT.Wz0..0 60
0:-
wI-
0(1) 5000 LT.:::)0..
a: 40
C'I 5CI)
"0 RT.,
...J W 0
...JO
0:::)
o:!::
-5I- LT.I-
«
-10
60
...J <fi- RT.«~z' 50O:u O
w-j::1-1-- 40«(1)(1)
...J 0 LT.0..
30
80
(b) Lat~ral comparisons.
Figure 3.- Concluded.
11
WING INCIDENCE Iw =7.5
0
COLLECTIVE STICK Xc =25%
OR AS REQUIRED
o FLIGHT 21
• FLIGHT 22, AUXILIARY ENGINES
GROUND IDLE
• SIMULATION RESULTS, 5-83
•
•
•
•
10
N UP
5
o
NDN
-5 '--__-I- ..L...-__.... ""'--__--I. -L-__--.I
••
• ~---0--..r,{ ~~'--'""
• •...
50
AFT
40
30
FWD20 '--__........__--.l -L-__--I. --'-__----I
60
•
• •
•50
UP
40
30
DN20 '--__--I- ..I..-__--'- ..........__---I. ...L-.__---'
•
•
•
•
•
. ..
15
N UP
10
5
N DNOL...-__.... ...L-. "'--__--L ....... "'--__---'
180160
~
•
60 80 100 120 140
CALIBRATED AIRSPEED, knots
10
N UP
5
o
NDN
-5 '-- -J- ..L...---....----'--__---I. ...L-.__--.I
40
(a) Longitudinal comparisons.
Figure 4.- RSRA trim level flight; collective stick = 25%.
12
•180
•
•
Q':)o~ 0 0
160
o
•
•
•
• 0
o FLIGHT 21
• FLIGHT 22, AUXILIARY ENGINES
GROUND IDLE
• SIMuLATION RESULTS, 5-83
80 100 120 140
CALIBRATED AIRSPEED, knots
~
•
" . ..
~..'.•
.'
60
WING INCIDENCE Iw = 7.5
0
COLLECTIVE STiCK Xc =25%
OR AS REQUIRED
Cl 10Q) RT.
"C
a.: 5
-I
C/)
0W
0 LT.
C/)
-5
12
~ 0 Cl 10I-wQ)
C/)'"O LT.o C/) •
a::wJ: 8
-Ia::u
_c..1-
«~a:: 61--
RT.
4
-I 70«~
0° RT.w, •
c.. 2 600
a::-
wt::oc/) 5000 LT.:::>c..
a:: 40
Cl 5Q)
'"0 RT..
-I W 0
-10
0:::>
a::t::
-5I- LT.I-
« -10
60
-I *. RT.
«::,,::2 50a::u O
w-j::1-1-- 40«C/)C/)
-I 0 LT.c..
30
40
(b) Lateral c6mparisons.
Figure 4;~ Concluded.
13
..
1. Report No. 2. Government' Accession No. 3. Recipient's Catalog No.
NASA TM-85863
4. Title and Subtitle 5. Report Date
, December 1983ROTOR SYSTEMS RESEARCH AIRCRAFT:
FIXED-WING SIMULATIONS' RESULTS 6. Performing Organization Code
7. Author(s) 8. Performing Organization Report No.
Robert M. Kufeld A-9549
10. Work Unit No.
9. Performing Organization Name and Address T-6565
Ames Research Center 11. Contract or Grant No.
Moffett Field, Calif. 94035
13. Type of Report and Period Covered
12. Sponsoring Agency Name and Address Technical Memorandum
National Aeronautics and Space Administration 14. Sponsoring Agency Code
Washington, D.C. 20546 532-03-11
15. Supplementary Notes
Point of Contact: Robert M. Kufeld, Ames Research Center, M.S. 237-3,
Moffett Field, Calif . 94035 FTS 448-6573 or (415) 965-6573
16. Abstract
This report covers the setup, validation, and results of the Rotor
Systems Research Aircraft (RSRA) fixed-wing, moving-base simulation performed
in May 1983. The emphasis of the simulation was to familiarize the pilots
with the RSRA's fixed-wing configuration, which has never been flown.
Additional information concerning stall speeds, minimum control speed, and
various gross weights were recorded and included in the report.
17. Key Words (Suggested by Author(s)) 18. Distribution Statement
Rotor Systems Research Aircraft Unlimited
Fixed-wing simulation
Variable-incidence wing
Handling qualities Subject Category - 05
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price'
Unclassified Unclassified 16 A02
'For sale by the National Technical Information Service, Springfield, Virginia 22161




Rotor systems research aircraft: Fixed-wing simulations results

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