Appendix A
To determine if errors existed in the leakage mass flow Appendix A parameters, the minimum-bleed, fixed engine nozzle data RCS Nozzle Mass Flow Parameter were examined. The total bleed flow measured in this case represents the total installed RCS leakage for the Adjustments for Leakage RCS valves in their nominally closed positions. On the Ground tests were performed with NASA Ames' basis of these data and the remaining results from the YAV-8B to validate the nonlinear simulation model individual valve-opening tests, it was decided to adjust representation of the RCS bleed and leakage. The aircraft the mass flow parameters representing the valve leakage.
was equipped with the duct pressure taps, rotary poten- RCS bleed flow data from all of the ground tests tiometers, and the calibrated engine described in the main involving individual RCS nozzle openings were used to text. Results from these ground tests are presented in determine the leakage corrections. The total bleed flow as reference 5. Modifications to the mass flow parameters predicted from isentropic flow theory, rh tOtisen, and the representing leakage are presented here, along with a total bleed flow as predicted by the simulation model, sample of the test data to illustrate the effects of these changes. fiatOtsim, are the sums of the RCS nozzle bleed flow rates.
In mathematical form Analysis of these tests compared the RCS bleed deter- mination method of the nonlinear aircraft simulation model and the isentropic flow theory method (as shown fiatot i_n = ril fPisen + ril api_ n + ril rWisen in the main text in eqs. (5) through (13)) to total bleed (AI) + lh lw isen + ril yaw isen measurements from the calibrated engine. The first ground tests determined the bleed rates through each RCS nozzle when each valve was opened independently of the rntotsim = rilfPsim + lhapsim + riirwsi m valves on the remaining RCS nozzles. The engine nozzles (A2) were fixed at a 40 ° downward deflection from the + m lw sim + m yaw sim horizontal, setting the RCS butterfly valve in the fully open position. During the testing of each RCS nozzle, the The simulation model and isentropic flow theory other valve linkages were disconnected to prevent calculate reasonable mass flow rates for open RCS inadvertent valve openings on the remaining nozzles.
nozzles. Hence, the actual leakage is defined as the total Bleed flow data were collected for throttle settings mass flow rate determined from the engine calibration between 85% and 100% of maximum RPM, with the minus the amount that is being bled through the currently pilot opening each valve in a series of stepped control open RCS nozzle, or deflections.
Additional bleed flow measurements were recorded with lia tot eag - ria(nozzle in use)i_n = ril leakageisen (A3) the valves closed, the engine nozzle deflection angle fixed at 40 °, and the RPM varied from 85% to 100%. This provided data on the combined leakage of the valves.
rn toteag - rn (nozzle in use) sim = rn leakagesim (A4) Figure A1 shows typical results Using the RCS nozzle mass flow parameter data from reference 4. Note that the The values of rhtoteng, rntotsi m, and rntotise n for the total bleed resulting from the simulation model and from individual nozzle tests contain the mass flow rate of the isentropic flow theory generally agree, but disagree with open RCS nozzle. Therefore, the difference between the total bleed calculated from the engine calibration rh toteng and the other total mass flow rates represents the equations by roughly a constant. Both analytical methods error in the RCS leakage for each calculation method. The predict a higher level of bleed flow usage than was percentage error in mass flow leakage for the closed (but actually demanded from the engine. Since the engine still leaking) RCS valves is given by calibration data are considered accurate, an error in the p.
mass flow parameters representing leakage was sus- Error in Total Bleed Flow pected. These parameters would be "constant" factors % Error in RCS Leakage - x 100% Actual Leakage when only one valve is open, since the other RCS valves (AS) are nominally closed.
Table A1. Revised RCS nozzle leakage characteristics
%Error inRCS Leakage, Isentropic Flow Theory
rhtoteng - hatOtise n (A6) RCS Original leakage Revised = x 100% nozzle mass flow leakage mass m leakageise n parameter fl0w parameter
m 'Po) (m 'Po)
% Error in RCS Leakage, Simulation Front pitch 0.120 0.072 Downblowing wing 0.150 0.089 hatot eng - hat°t sim (A7) Upblowing wing 0.120 0.072 = × 100% Rear pitch/yaw 0.200 0.125 haleakagesi m These errors were averaged between the simulation model Figure A2 shows the total bleed results after the leakage and the isentropic flow method and used to recalculate the mfp revision for the same left roll valve input illustrated RCS leakage mass flow parameters. Table A1 lists the in figure A1. These revised mfp leakage values were used original closed-valve mfp values and their revised values.
in the determination of the individual RCS nozzle bleed The difference between the new and old mfp values is flow rates presented in this report.
approximately 40%.
Appendix B
LetM i =M n + A, IAI <Mn, where Mn equals an initial Appendix B estimate of Mi. Substituting into equation (B5): Iteration Method to Determine Mach Number at Each Pressure Tap 1.728(M n + A) (B6) A R = Let A* be the cross-sectional area of the RCS nozzle [1 + 0.2(M n + A)2] 3 opening, where M = 1. The duct cross-sectional area where pressure tap i is located is represented by Ai. The area ratio A R is defined as Expanding the denominator A m 1.728(M n + A) (B7) A R = A R = A-- T (BI) The area ratio is used as the initial estimate for the Mach number at the pressure-tap location, M n- Equation (B2) Assuming A 2 is small determines successive values of Mach number: 1.728(M n + A) Mn+l =Mn + A (B2) AR --_ (B8)
(,+oaMen +04Mn4'
The interval A is determined by the expression 1.728(M n + A)
( A R 1 + 0.2M - 1.728M n (B9)
A= 1"728- I'2ARMn(I + 0"2M2) 2 (B3)
2>31 ,2Mn, ]
(,+02Mn
The iteration on Mach number continues until the absolute value of A is less than 1 x 10 -6. The stagnation Solving for A pressure calculation, equation (13) in the text, uses this final value of Mach number.
AR(I + 0.2M2)3 + AR(I.2MnA)(I + 0.2M2) 2 The remainder of the appendix shows the derivation of (BI0) equation (B3) from isentropic flow theory. Mi, the Mach = 1.728(M n + A) number at the pressure tap, is related to AR and the ratio of specific heats, T, as follows: (T+l) A R 1 +0.2M - 1.728M n A= (B4) AR =MiI/T___)(I+__M2)] 2(,-I) 1"728- I'2ARMn(I + 0"2M2) 2 (BII) Assuming "y = 1.4 for air 1.728M i A R - (B5) (1 +0.2M2) 3 4. Melsom, R. K.; and Gerhold, M. N.: AV-8B References Reaction Control System Performance. British 1. Fozard, John W.: The Jet V/STOL Harrier An Aerospace P. L. C. report number BAe-KGT-R- Evolutionary Revolution in Tactical Air Power.
V8B-01100, January 1982.
British Aerospace Aircraft Group, Kingston- 5. Borchers, P. F.; Moralez, E.; Merrick, V. K.; Stortz, Brough Division, July 1978.
M. W.; and Eames, D. J. H.: Determination of 2. McDonnell Aircraft Company: YAV-8B Simulation YAV-8B Reaction Control System Bleed Flow and Modeling, Volume 1: Aircraft Description Usage. AIAA-92-4232, August 1992.
and Program Summary. NASA CR-170397, 6. Ruscoe-Pond, M. G.: Harrier Reaction Control March 1983.
Data. British Aerospace P. L. C. report 3. Eames, D. J. H.: Pegasus Engine 8735 Bleed Flow number P. O. N. 1216, December 1967.
Calibration at Patuxent River. Rolls-Royce Inc.
ATLR 0703, December 1987.
.... VTO and hover -- -- • Decelerating transition -- Accelerating transition Without autostabilization Q I l \ O l \ l \
_i
% "% O I- • ...'-....
100 1 "10 ,ID E %, %, E _,_.
o. _20 I- 0 20 40 60 80 100 Percent of time above stated flow Figure 1. Typical bleed usage for Harrier technology-demonstrator aircraft (adapted from ref. 1).
m llne .......... _ ...... I .p. • ..---" constant r ......... I'.p .nl. . -
I
..... increasing Short lift rating Normal lift rating Rated time mean bleed 0 H.P. bleed offtake - Ib/sec Figure 2. Engine lift rating for the Harrier (adapted from ref. 1).
Yaw/aft pitch RCS valve (top view) (front view) (_ Nozzle bodies RightrollRCSvalve/___ _ _l_ (_ (_ Valve shutters (_ Actuator linkage Forward pitch RCS valve (side view) p.
Butterfly valve Figure 3. RCS layout with RCS nozzle and valve details.
]5 0.166-in. diameter through reaction control nozzle Outboard Fo Pressure transducer installation Shutter pivot Outboard Flow direction Downward Section A-A Figure 4. Typical RCS pressure-tap installation (roll nozzle).
]6 Yaw valve _ FS 599.0 /--/I w,120.5 Fuselage datum o
w,,°.oo
-- _ _ L___ I _ Rear pitch valve • I 8° -.___1 ' FS 605 51 Fr°nt pitch valve /11 _-_---_J i/ 8° " II _"--_ " FS 137.48 /! ;/ WL 114.63 WL 70.36 / .....1 'l / Roll valve BL 0 BLO "----_/ _ .... ?'°_-,- i /',_-_ FS 432.45 • I _ WL 83.89 BL 177.84 All dimensions in inches FS - fuselage station WL - water line BL - butt line Figure 5. YA V-8B reaction control nozzle locations and thrust lines for maximum shutter deflection (as taken from ref. 2).
i?
Total Front pitch ....... Dwnb. wing ............ Upbl. wing Aft pitch Yaw
\ -
20 40 60 80 100 Percentage of time above stated flow Figure 6. RCS bleed air usage during hover.
_q 40 m
J!
2o
I I I I _ II I t i t t t III I II|l I I I ] lilt[ I I I i I I I I I1 I I I t I it i I [ 0 20 40 60 80 100 Percentage of tlme above stated flow Figure 7. Percentage of available RCS bleed air used during hover.
Total
1° V
Front pitch Dwnb. wing Upbl. wing Aft pitch Yaw Figure 8. RCS bleed air usage during longitudinal translations.
2O 100- . Longitudinal translations 80 Hover - 60 4O 20- t I I I I i , i i I I I i I I I i I I I I'1 I I I I I I I I i i I I I i I I I I I i I I I I I i i I 0 20 40 60 80 100 Percentage of tlme above stated flow Figure 9. Percentage of available RCS bleed air used during longitudinal translations.
2] Total Front pitch ....... Dwnb. wing ............ Upbl, wing Aft pltch Yaw \ i t t i I I I I I I I I I I I I I i t I I I I I I I I I I I I t t t I i I I I I I I I t I t t t I I 0 20 40 60 80 100 Percentage of time above stated flow Figure 10. RCS bleed air usage during lateral translations.
Lateral translatlons
,o F
" Hover Q a.
Ii i i I I i i i i I I I I I I I I I I I l T I I I I I I I I I I I i I i i i I I I I I I I I i I l I • 0 20 40 60 80 100 Percentage of tlme above stated flow Figure 11. Percentage of available RCS bleed air used during lateral translations.
14 I Total Front pitch I_,,,_ ....... Dwnb. wing I \ i- \ ............ Upbl. wing - 8 1°I ....
.................... .'..'.:..'.:..-.,--____ ............. "__ ----,._ _.... ____ I Ill J I It I I I I II I I I It i It t l ill It I I I I I i t I i t I i i i I I t n n a I 0 20 40 60 80 100 Percentage of time above stated flow Figure 12. RCS bleed air usage during pedal tums.
Pedal turns n i I ii I i i = =1 , i iiI illll III I III I m I I = III I I I o I It ' I I I ' = = I 20 40 60 80 100 Percentage of time above stated flow Figure 13. Percentage of available RCS bleed air used during pedal tums.
Total Front pltch Dwnb. wlng Upbl. wlng Aft pltch Yaw m 80 100 0 20 40 60 Percentage of time above stated flow Figure 14.RCS bleed air usage during arrested descents.
6O I Arrested descents Hover _.a L-- (I) n tl i i n i t i i t i I t i i i t i i i i t i i i i i i i t i i i i i i i i t , Ii I t I I t I I I ] 20 40 60 Percentage of time above stated flow Figure 15. Percentage of available RCS bleed air used during arrested descents.
0 20 40 60 80 100 Percentage of time above stated flow Figure 16.RCS bleed air usage during vertical landings.
100- VerUcal landings 80 ....... Hover
!
i
2O ti i i i i i i i I I i i i i i i i i i i i i i i i i i i i i i I i i i i i i i i i i i i I i i i i i 20 40 60 80 100 Percentage of time above stated flow Figure 17. Percentage of available RCS bleed air used during vertical landings.
Total Front pitch Dwnb. wing Upbl. wing Aft pitch Yaw o m • ° , . • • ° ° o 0 0" 40 60 80 100 Percentage of time above stated flow Figure 18. RCS bleed air usage during short takeoff.
3O Short takeoff Hover
|,o
J_
|
a.
20 40 60 80 Percentage of time above stated flow Figure 19. Percentage of available RCS bleed air used during short takeoff.
14 - Total 12 - Front pltch Dwnb. wlng ............ Upbl. wlng 10 _ .... Aft pltch
I\
I\ ..... Yaw
rn 4 I "_'_'_ ._..,_,_. " ............................................... ..._...-_-_:.--. - - , ..... "-',.----- - ,r'--"-'_ ....
I I I I I I I I I I I t t t I ;'t tTI I I I I 1 "i' t _ T r"T-'i"t_rT i i f-i i t i i n n 'n'u n 0 20 40 60 80 100 Percentage of time above stated flow Figure 20. RCS bleed air usage during approach and transition to hover.
Approach and transition Hover - 60 Q D,, 2O I i i ii I I i , I , i I , III III i i i i I i I i ' I i I i ' I i i i ' I i i J I I i ' I i I 0 20 40 60 80 100 Percentage of time above stated flow Figure 21. Percentage of available RCS bleed air used during approach and transition to hover.
Total Front pitch Dwnb. wlng ............ Upbl. wlng I Aft pitch Yaw
T
i i
\
m 4 !
, . • . . ._q I • _'.% .................... _, ..................... ._-_.'._,........._.,,=_,,=__'_ i i I I I I I I I I I I I I II I _ u I _ n n ,I n n n_ I n n n _ I n n n n I _ _ u nT_7"T'"r-I 0 20 40 60 80 100 Percentage of time above stated flow Figure 22. RCS bleed air usage during slow, rolling landing.
r 160- Slow landing Hover 80 -
i
&40
!
ii ii II iIi I i i i i] i Is III I III I I I III i I Ill I I III I I I I I I III 20 40 60 80 100 Percentage of time above stated flow Figure 23. Percentage of available RCS bleed air used during slow landing.
.6 [- Roll axls L Pitch axis Q.
_.'
0 20 40 60 80 100 Percentage of time above stated control power Figure 24. RCS control power during hover.
Roll axis
'F
Pitch axis ....... Yaw axis
"°_____
i ............... ii;i;i ...........
0 20 4O 60 80 100 Percentage of time above stated control power Figure 25. RCS control power during longitudinal translations.
Roll axis Pitch axis 1.0 Yaw axis ,,-, .8 ¢N
| .e
g
J
8 .4
.2 80 100 0 20 40 60 Percentage of time above stated control power Figure 26. RCS control power during lateral translations.
Roll axis
9 E
.8 / Pitch axis n ,7 mo_,mo.
.5
_._
_._
.2 .1 0 2O 40 60 80 100 Percentage of time above stated control power Figure 27. RCS control power dudng pedal turns.
Roll axls
s E
_'_'6 _ Pitch axis L_ _.,
8.2
0 20 40 60 80 100 Percentage of tlme above stated control power Figure 28. RCS control power during arrested descents.
4O Roll axis
8 E
Pitch axis .6 0 20 40 60 80 100 Percentage of time above stated control power Figure 29. RCS control power during vertical landings.
m Isentrop!c flow I m.,Q ,.Q_.
I-- I I I I I I I I v I I v I I m Simulation model -o_ 5 i I i I I I I I I I I I I I i I ,'_4 o_ v-2 I, I t I I I t I _=_-['JI I I I i I 10 20 30 40 50 60 70 80 Time (seconds) Figure A 1. Total bleed flow comparison for left roll valve deflections, _n -- 40°, 90% maximum rpm, original mfp.
Total bleed flow rate Total bleed flow rate Lateral stick input (in.)
(Ibm/sec) (Ibm/sec) Left ¢ _ _ Right I o m _ _] I i I o i I , i ,i i 1 i i i i ¢b
-
C_
-g
• 3 • _ _ • -_" __.
o
,f
o
i0
y
,/
II 4_ m _ o_ m _ [] I"1 Cb C_ Form Approved REPORT DOCUMENTATION PAGE OMB No.OZO4.018e Public reporting burden for this collection of information is estimated to average 1 hour per response, includingthe time for reviewinginstructions,searching existing data sources, gathering and maintainingthe data needed, and completingand reviewingthe collectionof information. Send comments regardingthis burden estimate or any other aspect of this collection of information,includingsuggestions for reducingthis burden, to Washington Headquarters Services, Directorate for informationOperations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Pro ect (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED April 1994 Technical Memorandum 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS YAV-8B Reaction Control System Bleed and Control Power Usage in Hover and Transition 533-02-37 6. AUTHOR(S) Paul F. Borchers, Emesto Moralez III, Vernon K. Merrick, and Michael W. Stortz 8. PERFORMING ORGANIZATION 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) REPORT NUMBER Ames Research Center A-93080 Moffett Field, CA 94035-1000 10. SPONSORING/MONITORING SPONSORING/MONITORING AGENCY NAME(S) ANDADDRESS(ES) AGENCY REPORT NUMBER National Aeronautics and Space Administration NASA TM-104021 Washington, DC 20546-0001 11. SUPPLEMENTARY NOTES Point of Contact: Paul E B orchers, Ames Research Cente_ MS 211-2, Moffett Field, CA 94035-1000; (415) 604-6115 12b. DISTRIBUTION CODE 12a. DISTRIBUTION/AVAILABILITY STATEMENT Unclassified -- Unlimited Subject Category 08 13. ABSTRACT (Maximum 200 words) Using a calibrated Rolls-Royce Pegasus engine and existing aircraft instrumentation and pressure taps, total and individual nozzle reaction control system (RCS) bleed flow rates have been measured on a YAV-8B Harrier during typical short takeoff, transition, hover, and vertical landing maneuvers. RCS thrust forces were calculated from RCS nozzle total pressure measurements, and control power was determined from the moments produced by these thrusts and the aircraft's moments of inertia. These data document the characteristics of the YAV-8B RCS with its basic stability augmentation system (SAS) engaged. Advanced control system designs for the YAV-8B can be compared to the original SAS based on the total bleed use and the percentage of available bleed used. In addition, the peak and mean values of the bleed and control power data can be used for sizing the reaction controls for a future short takeoff and vertical landing (STOVL) aircraft.
15. NUMBER OF PAGES 14. SUBJECT TERMS STOVL, Reaction control systems, STOVL stability and control, Preliminary design 16. PRICE CODE A03 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRAC 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION OF ABSTRACT OF REPORT OF THIS PAGE Unclassified Unclassified Standard Form 298 (Rev. 2-89) NSN 7540-01-280-5500 Prescribed by ANSI Std. Z39-18