Low-speed Wind-Tunnel Study of Reaction Control-jet Effectiveness for Hover and Transition of a STOVL Fighter Concept

--- - -,._. -- "- -- - -. --- _._ - _.

I

I

Appendix A are collapsed and stowed, and the ejector inlet covers are closed. For hover, attitude control is provided by reaction control jets located in the nose, wing, and Aircraft Description and Operational tail sections of the aircraft. For conventional flight , Modes control is provided by elevons and a rudder. During transition, both systems are used.

A three-view drawing of the E-7A configuration is presented in figure 1. The design employs an ejector- Figure 2 illustrates the proposed method of augmentor system driven by engine bypass air that achieving STOVL capability. For hovering flight , all is located in the wing root section near the apex of engine bypass air is ducted forward to the wing ejec- a large 60° clipped-delta wing. A two-dimensional tors. The ejector-augmentor combination induces a ADEN-type core nozzle is located rearward on the large secondary mass flow that increases the thrust undersurface of the aircraft for vectoring the hot output of the system. The core nozzle is deflected main-engine exhaust. The long diffuser units of the to turn the core flow 90° downward. During transi- wing ejector-augmentor system shown in the front tion, the core nozzle angle is varied and the engine view are employed to improve the efficiency of the bypass air is modulated between the wing ejector sys- design. As illustrated, the aircraft would operate in tem and the aft nozzle. For conventional flight , all the hover and transition flight modes. For high-speed engine bypass air is directed rearward through the flight , the aircraft is reconfigured. The diffuser units aft nozzle.

I

L_

Appendix B Therefore, (B3) Equations Used In Data Reduction Finally, Because of the geometry used for the control jets

Ve = JqOO

in the model, the flow exiting t he nozzles was very qj distorted. For this reason the following simp lifi ed (B4) mathematical expressions, which assume incompress-

ible flow, were employed. = I¥oo Voo

V- P· J J Determining Values of Ve To determine the values of effective velocity where qoo is measured and qj is calculated from ratio Ve, the wind-off values of the measured mo- equat ion ( B3 ).

ment (rolling moment 1 used for illus trat ion) and the geometric moment arm may be used to compute the jet thrust by Computing ENPR ( Bl ) Tj = l/Yj To compute the estimated nozzle pressure ratio where it is recalled that ENPR , l et ENPR = Pa + qJ .

(B5) ( B2 ) Pa where qj is calculated from equation (B3).

. -- - -------.----~- ------ ____ ~ ________ ----.1

Appendix C then

t:::.L) (S)0.42(p. )0 . 75

17V Tj p = -0. e Aj p~ - 1.893 Estimation of Control-Jet Effectiveness ( (C3) Empirical equations predicting the induced lift Th e increme nt in roll-control moment can be loss of a reaction control jet exhausting into a cross- written as flow are presented in reference 1. These equations t:::.L (C4) are presented here for convenience since they were t:::.l = TjYjr.

J used in the comparisons presented herein.

The empirical method assumes that the lift loss The above equations, as indicated in refe ren ce 1, due to jet-induced effects consists of two terms which apply to values of velocity ratio Ve up to 0.1 , to values are designated by the subscripts 0 and p. Thus , of S/Aj up to about 7000 , and to jet pressure ratios Pj/Poo up to about 45.

To adjust the above method for control-jet loca- t:::.L = (t:::.L) + (t:::.L) (Cl) T· T · T· tions near the wingtip and near the wing trailing J J a J p edge , the factors Kc and Kb were proposed in ref- erence 1 as follows: where

t:.L) ( S )0 .5 ( S )0 .6 8 8

3 2 2 2 (C5)

K o = 1 - 123 ( ~; )'

4V Tj 0 = (3V e - 2. e ) Aj + 0.41 V e . A j ( (C2) If Y' ) 13 (C6)

Kb = 1 - 0.8 b!2

( !!L < 1.893 P oo - then The total expression for the estimated increment in rolling moment is then given by and if (C7) Pj > 1.893 Poo --- - -----_._-- - --- --- - -- - -- -- - - - - --~ - References 6. Maskew, B.; Strash, D.; Nathman, J .; and Dvorak, F . A.: Investigation To Advance Prediction Techniques of the Low-Speed Aerodynamics of V/STOL Aircraft. NASA 1. Kuhn, Richard E.: A Method for Estimating Jet Reaction CR-166479, 1983.

Control Effectiveness. A Collection of Technical Papers- 7. Spreemann, Kenneth P.: Free-Stream Interference Effects AIAA 4th Applied Aerodynamics Conference, June 1986, on Effectiveness of Control Jets Near the Wing Tip of a pp. 237 - 242. (Available as AIAA-86 -1 805.)

VTOL Aircraft Model. NASA TN D-4084, 1967.

2. Fearn, Richard L. ; and Weston, Robert P.: Induced Veloc i ty Field of a Jet in a Crossftow . NASA TP-I087, 8. Foley, W. H.; Sheridan, A. E.; and Smith, C. W.: Study of Aerodynamic Technology for 1978. Single- Cruise- Engine 3. Aoyagi, Kiyoshi; and Snyder, Philip K.: Experimental V/STOL Fighter/Attack Aircraft. NASA CR-166268, Investigation of a Jet Inclined to a Subsonic Crossflow. 1982.

AIAA-81-261O, Dec. 1981. 9. Fearn, Richard; and Weston, Robert P.: Vorticity Associ- 4. Kotansky, Donald R.: Jet Flowfields. Special Course ated With a Jet in a Cross Flow. AIAA J., vol. 12 , no. 12 , on V/ STOL Aerodynamics, AGARD-R-710, Apr. 1984, Dec. 1974, pp. 1666- 1671.

pp . 7-1 - 7-48 . 10. Vogler, Raymond D.: Surface Pressure Distributions In- 5. Wood, M. N.: Jet V/STOL Aircraft Aerodynamics. Ann. duced on a Flat Plate by a Cold Air Jet Issuing Perpen- N. y. Acad. Sci., vol. 154, article 2, Nov_ 22, 1968, dicularly From the Plate and Normal to a Low-Sp eed Free- pp. 893 - 920.

Stream Flow. NASA TN D-1629, 1963.

Table 1. Model Geometric Characteristics Wing: Area, ft 14 .1885 Aspect ratio 1.665 Taper ratio .

0.115 Span, in . .. 58.320 Root chord, in. 62.860 Tip chord, in. 7.212 Mean aerodynamic chord (MAC) , in. 42.402 Leading-edge station of MAC, in. FS 34.239 Span station of MAC , in. BL 10.720 Leading:'edge sweep, deg Trailing-edge sweep, deg ... -10 Airfoil . . . .

NACA 64A004 Incidence, deg

o

Dihedral, deg .

· . 0 Twist, deg ..

· . 0 Elevon area, ft 1.7026 Vertical tail: Area, ft .. 1.2319 Aspect ratio 1.294 Taper ratio .

0.437 Height , in. .

15.150 Root chord, in. 16.293 Tip chord, in. 7.125 Leading-edge sweep, deg · 47.5 Airfoil: Root ... . 5.3-percent-thick biconvex Tip .. .. . 3.0-percent-thick biconvex Rudder area, ft2 . . . . . . . . . 0.2621 Fuselage: Length (nose boom removed) , in. 84.5415 1 2 ------ - ------ ----- ~ \ [ , .. ... --:--------

lt~~~~;:::,(~'-,---- -

-~:.-= .. ' "'-n' '''' 'T 'Tl,,''''i - - --- I I 1111 I I I I' , I I ;

::IIIIIIII::~ I S}

,11111111'1,' I i I I- i -i -i - i -i - i " i · i-I~I\"i ~ .Ji .1I .li~~ ~ :;~ ..! - - - - - -" -=7 , , ~~:::~"-"-:a: : Overall span _

,--

: :: :::: ... --- \_-":-- .. ----- (32 ft 4.8 in .)

Overall I height (17 ft) I Overall length (49 ft 5 in.)

Inlet cover ~/ I - - -- .... - .....

"'11 1 11'1 •• 11'1 '11 "' 11 ""'11"'" .11111."'" III1I II1 IIII Figure 1. The General Dynamics E-7A configuration.

,...

~

L . . __

---------- ---------- -- . _---

, -

....

II>- (a) Hovering fli ght .

fit,

.... :::~': 3'-

.. .. .. ..

~

!!

Partial fan ~ P~I fan

air to ejectors Core air air to aft vectored nozzle (b) Shor t-ta ke off- and -t ransition fli ght .

~ ::::::::::: III ........ Fan air, .::.:..:..: ............... .,..

afterburned Core air, as required afterburned as required ( c) Conventional flight.

Figure 2. Mo d es of operation of the E-7 A.

L-85-5629 Figure 3. Photograph of 15-percent-scale E-7 A model.

....

O'l Nose jet Jet Locations Control jet xj . ln.

Yj ' in.

Baseline jets -20.240 ±16.160 CoG.

Baseline jets Trailing-edge jet -28.115 +16.160 Wingtip jet - 20 .240 +29.348 Yaw jet Jets on long extension -20.240 ±35.535 Wingtip jet Nose jet +35 .900 0 i a-32.350 Yaw jet (b) i a Jet exit 1.50 in. aft of wing trailing edge.

b Exit at fuselage surface with jet directed through centerline parallel to lateral direction.

Trailing-edge jet long extension (a) P lanvi ew of control-jet locations.

Figure 4. Control-jet locations tested. Dimensions are given in inches .

--_._--- --- - .' -- - --- -- - --- -- ~ ----

-- ·-

8.23 ~-·~I

_~~~~~~ ~~~~~~~~~~,~\~~~~~F~~~~~_~eteff IUx

Trailing-edge control jet (side view) Jet efflux Wingtip control jet (front view) Jet on long spanwise extension (b) Sketches of alternate jet locations.

Figure 4. Concluded.

____ --.J ~- - -- - -- _. ---- ,...

§ {Y ~

8?'...Q==

Right-wing baseline

-.o2L ~

control jet I ~ .~~~ -.04 C m -.06 ENPR 0 1.0

-.08 t-

/

1.0

o 1.56

L -.10 6 1.86 \l 2.21 Ll 2.55 .04 .3 r- .2 .02 .1 C 0

CL z

-.02 -.1 -.04 0 0 2 3 5 6 2 2 q ex> , Ib/ft q ex> , Ib/ ft Fig ur e 5. E ff ect of fr ee-str eam dynamic press ure on model wit h design right-wing control j et operating at several pressure sett ings. a = 0°; {3 = 0° ; D e L = D e R = 0°.

, , Right-wing baseline control jet MEASURED ENPR 01.56 D 1.86 <) 2.21 {). 2.55 CALCULATED --- NPR < 1.893 - - NPR = 2.50 1.4 1.2 1 . )Itt"- __ _ .8 1'/10 .6

"'"

.4 .2 I .

o

.06 .08 .05 .07 .09 Ve (a) Right-wing roll jet.

Figure 6. Effectiveness of baseline roll jets for transition conditions. Q = 0°; (3 = 0°; Oe,L = Oe,R = 0°.

--- -. - -_. - -- MEASURED ENPR 01 .50 01.83 02.19 J6. 2.59 CALCULATED --- NPR < 1 .893 - - NPR = 2.50 Left-wing baseline control jet 1.4 1.2 I'll

o

.4 . 2

o

(b) Left-wing roll jet.

Figure 6. Continued.

MEASURED ENPR

o 1.95

o 2.52

<> 3.09

CALCULATED --- NPR < 1.893 - - NPR = 2.50 Left-wing baseline control jet 1.4 1.2 I'll

o

.2

o

.04 .05 .06 .07 .09 (c) Left-wing roll jet.

Figure 6. Concluded.

4 Crossflow ..

y/d OL...- __ ..L.---L_...I.L.---II -1

-3 o 1 2 3 4 6

x/d Figure 7. Planview sketch of constant pressure contours on flat plate at zero angle of attack with circular jet exiting at 90° to free stream. (See refs. 2, 9, and 10.)

------ I .4 .3 R ig ht- wi ng basel in e .2 control jet .1 CmO~ - . 1 -.2 -.3 ENPR -.4

o 1.0

o 2.21

1.6 1.0 1.2 .6 .8 CL .2 CD .4 -.2 -.6 -.4 -5 15 -5 15 5 25 35 5 25 35 45 a , deg a , deg (a) Wind axis data.

Figure 8. Effect of angle of attack on longitudinal aerodynamic characteristics with and without th e right-wing baseline roll jet operating. Q: = 0°; {3 = 0° ; O e, L = O e, R = 0° ; and q oo = 4 lb / ft .

~ ~ ---- ----- t-:) ~ .4 ENPR .3

o 1. 0

Right-wing baseline

o 2 . 21

control jet .2 . 1 C

a

m -.1 - .2 -.3 -.4 .05 1.6 .03 1.2 .0 1 .8 C A CN -.0 1 .4 -.03

a

-.05 -.4 -5 5 15 25 35 - .5 15 45 5 25 35 a, deg a, deg (b) Body ax is data.

Figure 8. Concluded.

.----- -- --- ---- - ---~---- Right-w i ng baseline control . 08 .06 .04 .02 C 0 -.02

ENPR

o 1.0

-.04

o 1.56

o 2.21

- .06

-.08L---~--~----L- __ 7= __ -l __ ~~ __ ~ __ ~~ __ L-~

-5 35

a, deg

Figure 9. Variation of model rolling-moment coefficient with right-wing baseline control jet operating at several pressure sett ings with qoo = 4 lb/ft .

~ C11

l __

~ 0) .04 . 03 Right - wing baseline .02 control jet .01 C z -.01 -.02.

ex = 0°

-.03 ENPR -.04

o 1.0

o 1.56

. 04

o 2.21

.03 .02 .01 C z -.01

ex = 20°

-.02r ex = 10 °

-.03 -.04 -25 -25 - 15 -5 5 15 25 ~,deg '?

(a) qoo = 4 Ib /f t .

Figure 10 . E ff ect of sideslip angle on model rolling-moment coe ffi cient wi th right-wing baseline control jet oper at ing at several pr essure settings.

.04 .03 Right- wing baseline .02 control jet .01

c[

- . 0 ;'V'.------' ex = 0° ENPR .06

o 1.0

o 1.56

.04

o 2.21

C 1 0/< .."..." q ','>' oc:: -.02 -.04

•

-.06. , , I , v -20 -12 -4 4 12 20 12 20 ~,deg ~,deg (b) qoo = 2 lb/ft .

Figure 10. Concluded.

~ ~ ------

I

~ .08 ao

ENPR = 1.0

.04~

Right - wing baseline control jet

.06, ~I

~

-

.02 C[ 0 v _1 I

"'~ •

-.02 -.04 -.06 -.08 oe R , -20° 0° .08r I 20° .06

ENPR = 1.56

ENPR = 2. 21

.04 .02 C[ 0 -.02 -.04 , - . 06 -.08 -5 15 -5 15 5 25 35 45 5 25 35 45 a, deg a, deg Figure 11. Effect of elevon deflection for right-wing baseline control jet operating at several pressure settings .

f3 = 0° ; q oo = 4 l b/ft ; D e, L = 0° .

Wing-trailing-edge jet MEASURED ENPR 01.37 D 1.65

<> 1.97

62.38 CALCULATED -- NPR < 1.893 1.4 1.

0 6

.8 1 '11 .6 .4 .2

o

Figure 12. Effectiveness of trailing-edge roll jeVfor transition conditions. a = 0 °; {3 = 0° ; D e,L = De,R = 0°.

- -- -- -- -- Wingtip jet ~ MEASURED ENPR 01.46 D 1.70

<> 2.02

~ 2.37 CALCULATED --- NPR < 1.893 - - - NPR = 2.50 1.4 1.

Do

<>~ <> <>

06 Do

~ .8 I'll .6 .4 .2

o

Figure 13. Effectiveness of wingtip roll jet for transition conditions. a = 0° ; {3 = 0°; 8 ,L = 8 ,R = 0°.

e e

__ J

- -- " ~- ENPR 0 1.68 2.08 C 2.49 2.97 Jet 1.4 1.2

o 0

.8 I'll 0 .6 .4 .2

o

(a) Long extension on left wing.

Figure 14. Effectiveness of long-extended roll jets for transition conditions. Q = 0°; f3 = 0°; be,L = be,R = 0°; solid line indicates value at [' / [0 = 1.0.

I

I

I

_J

Jet on long extens ion ~ • ENPR 1.62 0 1.77 2 . 03 6- 2.33 1 .4 1 .2

o

1 .~~------------~~ . 8 /'//

o

.6 .4 .2

o

(b) Long extension on right wing.

F igure 14. Concluded.

Nose jet ENPR

o 1.36

o 1.98

02.58 63.20 1 .4 1. 2 1 .nA----------~~~--------------------------------

~rP~8 ~

o

Bo

o

o

.8

o

.6 .4 .2

o

Figure 15. Effectiveness of nose jet for tran sition condition s. a = 0 °; (3 = 0°; 8 • = 8 • = 0°; solid line e L e R indicates value at m' /mo = 1.0.

-- --- ~ Ill- 1.2

o

o

o

1.0

o 0 0

6 66060S

o

o

o

.8 n'ln .6

o

./ I I

ENPR

0 1.28 :=:> i:i~ : lj;; . )

.4~ ~IC "'~"+lr" 77:in

0 1.81

o 2.42

6 3.06 --- .....

Yaw jet .21 - 0 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 . 11 Ve Figure 16. Effectiveness of left yaw jet for transition conditions. a = 0°; f3 = 0° ; Oe ,L = Oe ,R = 0° ; solid line indicates value at n'lna = 1.0.

--- - --- ~----- -~~---- ~-- ------ -

-- -- -- -- - ---- ------ --------- -- ---------~------------ --------------~--------~---------~-----~ . 14 .1 2 . 10 . 08 .06 C y .04 .02 Yaw jet -.02 ENPR -.04

o 1.0

o 1.28

o 2.42

25 35 45 a , deg Figure 17. Lateral aerodynamic coefficients versus a for model with left yaw jet operating at several pressure settings. {3 = 0° ; q oo = 4 lb/ft ; O e, L = O e, R = 0°.

~ CI1 -- --- . --~ -- - -~ - ~ - --- ----- -- ~ 0') ENPR

o 1.28

o 2.42

Yaw jet .3 .2 . 1 ~ CN o I ~ ~ ~::o cr::::: ~----,(}= ~ ~ -.1 -.2~15~ -- ~O ----~--~~--~~~~--~~--~----L---~

a, deg

Figure 18. Jet-induced normal-force increments due to yaw jet operation. (J = 0° ; q oo 4 lb/ft ; O e L = O e R = 0° .

1 1 - __ I

l

}

NI\SI\

Report Documentation Page Na\lona t AeronautICs and Space Adml"ISHaloQn 1. Report No. 3. Recipient's Catalog No.

12. Government Accession No.

NASA TM-4147 4. Title and Subtitle 5. Report Date Low-Speed Wind-Thnnel Study of Reaction Control-Jet December 1989 Effectiveness for Hover and Transition of a STOVL 6. Performing Organization Code Fighter Concept 7. Author(s) 8. Performing Organization Report No.

Donald R. Riley, Gautam H. Shah, and Richard E. Kuhn L-16616 10. Work Unit No.

9. Performing Organization Name and Address 505-61-71-07 NASA Langley Research Center 11. Contract or Grant No.

Hampton , VA 23665-5225 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, DC 20546-0001 15. Supplementary Notes Donald R. Riley and Gautam H. Shah: Langley Research Center, Hampton , Virginia.

Richard E. Kuhn: San Diego, California.

16. Abstract A brief wind-tunnel study was conducted in the Langley 12-Foot Low-Speed Thnnel to determine reaction contro l-j et effectiveness and some associated aerodynamic characteristics of a 15-percent- scale model of the General Dynamics E- 7A STOVL fighter concept applicable to hover and transition flight. Tests were made with the model at various attitude angles in the tunnel test section and at various tunnel airspeeds for a range of control-jet nozzle pressure ratios. Eight reaction control jets were tested individually. Four jets were at the design baseline locations providing roll, pitch, and yaw control. The remaining four jets were tested at alternate locations for roll control.

Comparisons of measured data with values calculated using empirical methods were made where possible.

17. Key Words (Suggested by Authors(s)) 18. Distribution Statement VTOL Unclassified- Unlimited STOVL Control jets Jets in crossflow Subject Category 08 19. Security Classif. (of this report) 120. Security Classif. (of this page) 21. No. of pages122. Price Unclassified Unclassified 37 A03 NASA FORM 1626 OCT 86 For sa le by the National Technical Information Service, Springfield, Virginia 22161-2171