jul low - dticsecurity class, (ao thla topolt) unclassified dcj.a2sific"ation./oowng ca,...

* HIGH-LIFT CAPABILITY OF LOW ASPECT RATIO WINGS9=1 UTILIZING CIRCULATKIN CONTROL AND

UPPER SURFACE BLOWING

by

DTNSRDC/ASED-80/15d~5• 0

Jul low

UNCLASSTFTED!ECUMITY CLASSIFICATION OF THIS PAGE (hmen Date Entered)

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSREPORTDOCUMENTATIONPAGE13BEFORE COMPLETING FORM

I. REPORT NUMBER 2. GOVT ACCEISSION NO. S. MECCPIE'NT' CATALOG NUMBER

DTNSRDC/ASED-8O/15 ____________`J=__

4. TITLE (and Subtlltj C. TYPE OP REPORT 6 PERIOD COVERIED

HIGH LIFT CAPABILITY OF LOW ASPECT RATIO WINGSUTILIZING CIRCULATION CONTROL AND UPPER SURFACE InterimBLOWING 4. PERFORMINO OG0, REPORT NUMVIR

7. AUTuOR(e) 0. CONTRACT OR GRANT NUMEER(f)

Roger J. Furey

S. PERFORMING ORGANIZATION NAME AND ADDRESS 10, PIROGRAM E.s"MENT. PRO.JECT, TASKDavid Taylor Naval. Ship Research and AREA & WOMK 4NIT NiJMBER$Development Center Task. Area WF4i 421 000Bethesda, Maryland 20Cn4 Program Element 6224111

BWork Unit 1-1660-07911. CONTROLLING OFFICE NAMe. AND ADDRESS 12. REPORT DAT.E

Naval Air Systems Command July 1980AIR 320D 13. NUMBIER OF IPA1$ ..

Washington, D.C. 7314. FMONITORINO AGENCY NAME " ADDOESS(t01diItfernt from Con,.,oilln Olli'ef) IS. SECURITY CLASS, (ao thla topolt)

UNCLASSIFIED

Ca, DCj.A2SIFIC"ATION./OOWNG RAOINO"SCH•OL

6. �DISTRIMUTION STATEMENT (ot this Repot).

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

17. DISTRIiUTION STATEMENT (of the abstract entered In Block 20, it different from Repoft)

IS. SLIPPL-EMENTAIRY NOTES

1S. KEY WORDS (Continue on reverse side It n ,mocear' and identily by block number) 7'

Low Aspect Ratio WingsPowered-Lift Systems ,Lift Augmentation

20. ABSTRACT (Continue on reverse Ide, It neoeeeary, aid identity by block number)

A semispan research model with a 2-ft span wing was used to measurethe high lift capabilities of low aspect ratio wings utilizing powered-lift wconcepts. The concepts evaluated were the Circulation Control Wing (CCW),the Upper Surface Blowing (USB), and a unique combination of the two(CCW/USB). Wing tip sails were used as a means of increasing th(, effectiveaspect ratio of these wings during high lift.

Db JN 1473 EDITION OF I NOV 61 It OBSOLETE

S/N 0102-LF-01 4.6601SECURITY C;L.AI$11ICATION OP' THIS PlAGe (PWHnaIaR nl IfltslsE

~ ~ ~ . . . . - . . . .

UNCLASSIFIED J51CUIRITY CLASSIFICATION OF THIS AFJI[ (*Woun Date Itriredj

I(Block 20 continued) .1

The highest lift was generated with the CCW/USB configuration wherethe CCW is used as a thrust vectoring device and successfully turns theengine exhaust up to 165 deg. The lift augmentation resulting from theCCW and the turning exhaust flow prodiced a CL of 5.1 with an aspect

maxratio 4 wing. It is shown that this nearly approaches the theoreticalmaximum circulation lift (independent of the thrust contribution to

lift) that can be developed for a given aspect ratio wing. The wingtip sails are effective in reducing the induced drag of these powered-lift low aspect ratio wings under high-lift conditions. The induceddrag factor is reduced in some instances by 30 to 35 percent. The relativelylow drag of this configuration shows thet with correct operationalprocedure the potential for short takeoff and landing is significant.

IIIII

iins (fl\&l I

IIi t

UNCLASSIFIED

IICURImY Ct AIIFICATION Ol'THIS PAOUIRhl Daelta NIMered) I

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I

* TABLE OF CONTENTS

i Page

LIST OF FIGURES ................... . ............................... iii

SNOTATION............................................... vi

ABSTRACT ...................... .................................. I

ADMINISTRATIVE INFORMATION ............ ......................... I

INTRODUCTION ............................... .

MODELS, APPARATUS AND TEST PROCEDURES ....... . ....... . .. . 3

RESULTS AND DISCUSSION . ........ ....... . ....... 6

EVALUATION OF WING TIP SAILS ........................ 6

I CIRCULATION CONTROL WING.. ..... . ........ 8

UPPER SURFACE BLOWING ............... .. . 9

CIRCULATION CONTROL WING/UPPER SURFACE BLOWING . . . . . . . . . . . 12

CONCLUSIONS . . . . . ....... . ........ . . ....... .. 13

REFERENCES . . . . . . , . . . . . . ............... 69ILIST OF FIGURES

1 - Semispan Wing-Fuselage Model Configurations ......... .............. 15

2 - Semispan Model in USB Configuration ............. .................. 19

3 - Semispan Model in CCW Configuration with Wing Tip Fence ........ 19

S4 - Semispan Model in CCW/USB Configuration ......... ................ 21

5 - Supercritical Wing in Smoke Tunnel . ................ 23

6 - Longitudinal Characteristics of CCW Configurationwith Plain Wing Tip, AR= 4, 6 n = 40 Degrees .... ............. ... 26

7 - Longitudinal Characteristics of CCW Configurationwith Wing Tip Fence, AR= 4j •n 6 40 Degrees .... ............. ... 28

iii

LIST OF FIGURES .1Page

8 ". Longitudinal Characteristics of CCW Configurationwith Four Tip Sails, AR - 4, Sn w 40 Degrees . . . ......... 30

9 - Effect of Tip Sails on Induced Drag for 1CCW Configuration, AR w 4, 6n 0 40 Degrees . . . . . ...... 32

10 - Oil Flow for bUB model, AR - 4 ................... 33 1Ii - Longitudinal Characteristics of USB Configuration with

Wing Tip Fence, AR a 4, 5f - 40 Degrees, an 0 40 Degrees ...... 35 I12 - Longitudinal Characteristics of USB Configuration with

Four Tip Sails, AR w 4, 6 f - 40 Degrees, 6n a 40 Degrees . . . . . . 37

13 - Lift Components for USB Configuration, AR * 4, 1af = 40 Degrees, 6n n 40 Degrees ........ . . . . . . . . . 39

14 - Circulation Lift of COW and USE . . . . . . . . . . . 40

15 - Longitudinal Characteristics of USE Configuration withPlain Wing Tips, AR - 4, 6f - 60 Degrees, an - 40 Degrees . .... 41 I

16 - Longitudinal Characteristics of USB Configuration with 3Four Tip Sails, AR - 4, 6S - 60 Degrees, 6n a 40 Degrees . . . . . . 43

17 - Longitudinal Characteristics of USB Configuration with 1Wing Tip Fence, AR = 4, 6f • 60 Degrees, n = 40 Degrees ...... 45

18 - Oil Flow for USE Configuration, AR = 4,6f - 60 Degrees, an - 40 Degrees, a - 18 Degrees . . . . . . . . . . 47

19 - Effect of Tip Sails on Induced Drag for USB ConfigurationAR w 4 . . . . . . . .... . . . . . . . . . . . .. . . . . . . . ... . 49

20 - Lift Components for USB Configuration, AR a 4,6f w 60 Degrees, 6n - 40 Degrees . . . . . . . . . ........ . 50

21 - Longitudinal Characteristics of USB Configuration withPlain Wing Tip, AR = 4, Sf - 0 Degrees, 6 n n 0 Degrees ........... 51 1

ivI

'4 1 .. i, ,T ' • • --• -r '• • -- wq .m'I

LIST OF FIGURES

Page

22 - Longitudinal Characteriscics of USB Configuration withWing Tip Fence, AR - 4, 6f a 0 Degrees,6 n 0 Degrees, 4 . . a . I . 6 . . . . . . . . . 53

23 - Longitudinal Characteristics of USB Configuration withWing Tip Sails, AR w 4, 6t = 0 Degrees . . . . . . ... .. . 55

24 - Longitudinal Characteristics of USB Configuration withPlain Wing Tip, AR - 5, 6f * 0 Degrees,6 n 0 Degrees s s a . . . . 0 a 6 . . a a . , . a . 0 57

25 - Induced Drag Factor for USB Configuration,6t m 0 Degrees, 6n - 0 Degrees ......... 59

26 - Longitudinal Characteristics ot CCW/USB Configuration,AR m 4, CT -0.61 6n m 40 Degrees . P.. . .. . .. .. .# . 61

27 - Longitudinal Characteristics ot CCW/USB Configuration,AR = 4, CT m 1.19, 6n * 40 Degrees . a a . * . .. .... .. .a 63

28 - Longitudinal Characteristics ot CCW/USB ConfigurationAR m 4, CT w 1.45, 6n = 40 Degrees .. s & . a .a. . . . .. 64

29 - Blowing Coefficient versus Duct Pressuretor CCW/USB . . . . . . . .. . . . .. .. . . , 6 . * . , 66

30 - CCW/USB Static Engine Thrust Turning . .. ........... 67

31 - Induced Circulation Lift . . . . .. . . .. . . ... . 68

!v

Ii

I

, I

',V

NOTATION

AR Aspect ratio, b 2 /S

b Wing span, ft (m)

CD Drag coefficient, D/qS ICD Drag coefficient at zero lift

CL Lift coefficient, L/qS

CL Lift curve elope, aCL/aa ICL Maximum lift coefficientmax

CT ThrusL coefficient, T/qS

CP Momentum coefficient, ;Vj/qS

c Wing chord, ft (m) jD Drag, lb (N)

Oswald efficiency facLor

K Induced drag factor, 1/rARe jL Lift, lb (N)

m Mass flow IPT Duct total pressure, lb/in. 2 (N/m 2 )d

q Dynamic pressure, 1/2 p V2

S Wing reference area, ft 2 (m2 )

T Thrust, lb (m)

V Free-stream velocity, ft/sec (m/u) 3V. Jet velocity, ft/sec (m/s)

Angle of attack, deg

f Trailing edge flap angle, deg J6n Leading edge flap angle, deg

I

.,i ... I-

ABSTRACT

A semispan research model with a 2-ft span wing was used to measurethe high-lift capabilities of low aspect ratio wings utilizing powered-lift concepts. The concepts evaluated were the Circulation Control Wing(CCW), the Upper Surface Blowing (USB), and a unique combination ofthe two (CCW/USB). Wing tip sails were used as a means ot increasingthe effective aspect ratio of these wings during high lift.

The highest lift was generated with the CCW/USB configuration wherethe CCW is used as a thrust vectoring device and successfully turns theengine exhaust up to 165 deg. The lift augmentation resulting from theCCW and the turning exhaust flow produced a CL of 5.1 with an aspect

maxratio 4 wing. It is shown that this nearly approaches the theoreticalnmaximum circulation lift (independent of the thrust contribution tolift) that can be developed for a given aspect ratio wing. The wingtip sails are effective in reducing the induced drag of these powered-lift low aspect ratio wings under high-lift conditions. The induceddrag factor is reduced in some instances by 30 to 35 percent. Therelatively low drag of this configuration shows that with correctoperational procedure the potential for short takeoff and landingis significant,

ADMINISTRATIVE INFORMATION

The work reported was authorized by the Naval Air Systems Command (AIR 320)

and was funded under WF 41 421 000, Work Unit 1660-079.

INTRODUCTION

The operating constraints of many types of naval aircraft, (that is, restrict-

S11ed size in landing and takeoff platforms) and the ever-increasing costs ot build-

ing and supporting the current type of conventional aircraft carrier, have caused

considerable interest in short takeoff and landing (STOL) aircraft as a means at

3 reducing some of these difficulties.

The restriction of a 45-ft wing span whea operating from a landing platform

helicopter (LPH) size ship (which is often suggested as the nominal size for a tu-

ture sea control ship) necessitates the use of a less efficient low aspect ratio

wing. In order to realize the platform restrictions, the performance of such air-

cratt are compromised in cruise and range. The current effort completes a low

aspect ratio high-lift wing aerodynamics study at David Taylor Naval Ship Researcn

and Development Center (DTNSRDC) to develop the means of overcoming the platform

restrictions.*

A number of powered-lift concepts have been studied with high aspect ratio

wings as a possible means of achieving efficient STOL performance. References 2

through 6 present a number of these efforts in which the most promising concepts

are evaluated, Two of these approaches are the Upper Surface Blowing (USB) and the

Circulation Control Wing (CCW). Both concepts use the Coanda effect as a means of

augmenting aerodynamic lift.

In the case of the USB concept, the exhaust nozzle flow of an above-the-wing '

mounted turbofan engine is turned a predetermined amount by a continuous surface

trailing edge flap which provides the Coanda turning until separated flow on the 3surface occurs. In addition to the thrust component added to the lift direction,

a certain amount of lift augmentation is achieved by entraining free-stream air Iinto the exhaust flow.

The CCW concept employs a spanwise thin trailing edge slot which expels a jet

of air over a rounded trailiing edge. The Coanda turning of this jet relocates the

*Reported informally by Harris and Trobaugh ("Comparison of the Effect of the

Circulation Control Wing, Upper Surface Blown Flap, and Augmented Jet Flap on theShort Takeoff and Mission Performance of a Low Aspect Ratio Patrol Aircraft,"DTNSRDC TM-16-18-02 Apr 1978).

**A complete listing of references is given on page 67.

2

%-

trailing edge stagnation point and also entrains free-stream air, thereby

augmenting lift totally by supercirculation (there is no contribution to lift

from the jet force itself).

* A third and new concept, the CCW/USB, was also studied as a means of augment-

ing the aerodynamic lift and vectoring the engine thrust. In this approach, the

above-the-wing mounted engine has its exhaust turned by the trailing edge Coanda

3 slot and surface. The need for the larger trailing edge mechanical flap is thereby

eliminated. The three concepts with the dimensions and geometry of the basic semi-

span model are illustrated in Figure 1.

An additional phase of the program included enhancing the aerodynamic effi-

ciency of low aspect ratio wings through the use of wing ttp devices. The present

effort was limited to an evaluation of a wing tip fence and wing tip sails. The

wing tip sails are a derivative of those developed by Spillman,7 and were origi-

nally conceived as a means of alleviating induced drag on relatively high aspect

ratio wings in a cruise condition. The emphasis in this phase of the program is

on applying wing tip sails to low aspect ratio wings in a high lift condition in

order to (1) reduce the accompanying high induced drag for takeoff, (2) modulate

the high induced drag during landing approach, and (3) reduce the induced drag

of the unblown wing during cruise.

I MODELS, APPARATUS, AND TEST PROCEDURES

t A semispan model with a 14-percent thick supercritical wing was the basis for

Sall three configurations tested (Figure 1). Figure 2 shows the model in the USB

configuration, mounted on its grotndboard in the DTNSRDC 8- by 10-ft wind tunnel.

The wing is equipped to handle'trailing edge flap settings of 0, 40, and 60 deg.

The flap surface consisted of a continuous curved section on the inboard portion of

4 3"I,

*0!

the wing where the engine exhaust would impinge, The outboard win6 section was

equipped with double slotted flaps. The propulsion simulator was a 5,5-in. di-

ameter airdriven fan with two tip-drive turbines in tandem. The exhaust nozzle

had an aspect ratio 3.3 exit area, and was equipped with an insert with a 10-deg

turning angle deflecting the flow toward the wing surface. Additional sections jcould be added to the outboard portion of the wing to create aspect ratios of 3,

4, and 5. A leading edge flap which was 15 percent of the wing chord and projected 1at an angle of 40 deg to the wing chord was used with the 40- and 60-deg flap

settings. Transition strips of number 30 grit were placed approximately 1 in.

behind the wing leading edge.

The GCW model is shown in Figure 3. In this arrangement, the forward portion

of the wing is the saLme 14-percent thick supercritical section used in the USB con-

figuration. The trailing edge has been modified to provide for the internal air

passage, the trailing edge slot, and the rounded trailing edge that makes up the

circulation control wing. Figure 3 also shows the wing tip fence used to delay Itip stoll on some of the configurations.

In the CCW/USB arrangement presented in Figure 4, the forward portion of the Iwing and the engine assembly is identical to that of the USB model. The trailing

edge continuous flap section has been replaced with the CCW trailing edge. The

turning of the engine exhaust (thrust vectoring) is provided by the CCW trailing

edge. This configuration was investigated only in the aspect ratio 4 arrangement.

Since one of the objectives of the program was to increase the effectiveness

of low aspect ratio wings, an initial and limited portion of the test included an

appraisal of wing tip devices as a means of iucreasing tho effective aspect ratio.

In addition to the tip fence in Figure 3, an arrangement of "sails" was also

4¶ I i

Istudied. The tip sails were a derivative of those developed at the Cranfield

Institute 7 for the purpose of increasing the effective aspect ratio of a given

wing. In the Cranfield studies, tip sails were shown to reduce the induced drag of

the Paris aircraft by 20 percent. These sails were included in the present study

to observe it this approach would be equally effective *or low aspect ratio high-

lift conditions.

The tests were conducted in the 8- by 10-ft north subsonic wind tunnel at

DTNSRDC. This wind tunnel is of the closed circuit type and is capable ot contin-

uous operation at atmospheric pressure, Although the facility can generate dynamic

pressure up to 80 lb/ft 2 (3830 N/m2), the greater portion of this test was conduct-

ed at 20 lb/ft 2 (957 N/s 2 ). This provides a Reynolds Number of 0.8 x 106 per foot.

The semispan model was floor-mounted in the test section in a vertical posi-

tion using a base strut s>stem. The strut system is located beneath the tunnel

floor, and transfers the aerodynamic loads of the model to an external Toledo

mech&nical balance system. The balance system measures six component force and

moment data for recording on magnetic tape utilizing a Beckman 210 high-speed

acquistion system.

The wing-fuselage model was mounted in the test section such that only the

wing was attached to the balance frame. The fuselage was mounted to a boundary

layer splitter plate and was independent of the balance frame, with a small gap

existing between wing root and fuselage body. The forces and moments measured by

the balance frame are essentially wing-alone data in the presence of a body. The

gap between wing root and fuselage (Figure 3) allowed air to leak from the control

room below the tunnel while the tunnel was operating. To alleviate the resulting

flow interference, a root fence (Figure 4) was used to divert the leakage.

q5

The circu sr boundary layer splitter plate was 8 ft (2.44 m) in diameter and

served as a reflection plane for the semiipan model. This plate was mounted to the

tunnel floor wit'i a gap between the groundboard and floor to separate the boundary

layer; see Figure 2.

The propulsion simulator was calibrated with the model assetably on the balance

frame in t~e wind tunnel. The house air supply provides air at the rate of 1.2 lb/ Isec (5.38 N/s), and 165 lb/in2 (11.4 x 104 N/m2 ). At this rate, the engines can be Idriven at 26,000 rpm, which provided a thrust coefficient range from 0 to 2.0 for

the test conditions considered. The momentum coefficient for the CCW and 'CW/USB jportions of the program ranged from 0 to 0.6 and were determined from the expres-

sion:

C- ;Vi1J qS

where the mass flow was measured by a venturimeter located in the air supply line.

The jet exit velocity was determined assuming an isentropic expansion from the wing Iplenum total conditions to the free-stream static conditions.

The test procedure involved establishing tunnel and model conditions q, rpm,

and C and sweeping the model through small angular increment,;, Force and moment.

data were recorded at each pause from -5 deg angle of attack through the stall

point. .1

RESULTS AND DISCUSSION

EVALUATION OF WING TIP SAILS jThe main objective of the program was to evaluate the effectiveness of low

aspect ratio wings, in conjunction with powered-lift devices, in developing high I:

6

• ~.*. -..

lift. A means of enhancing the lifting effectiveness of low aspect ratio wings

also considered was the use of a tip fence and wing tip sails. Preliminary to the

8- by 10-ft tunnel tests was a brief appraisal of one of these methods, the tip

sails, through the use of a DTNSRDC smoke tunnel. A 14-percent thick, aspect ratio

4, supercritical wing was fabricated for this purpose, and is shown in Figure 5

attached to the smoke tunnel wall. Models ot the tip sails developed by Spillman

at Cranfield were fabricated to serve as a basis of comparison for other wing tip

flow enhancing devices eventually considered.

t The sails (shown in Figure 5a), in accordance with Reference 8, had a span

equivalent to 41 percent of the wing tip chord. The sail root chord was 16 percent

of the wing tip chord, and was highly cambered in the root section where the tip

vortex would be strongest. The purpose of the Cranfield tip sails was to reduce

the induced drag while the wing was at relatively low angles of attack or a cruise

condition, To utilize these methods at high-lift conditions, the sail local angle

of attack, orientation (roll angle about the wing tip), and chord position were

varied. The number of sails were varied in an attempt to favorably affect the wing

tip vortex by delaying its break-up to higher angles of attack. The tip vortex pat-

tern for the basic wing, without sails, is shown in Figure 5b.

The sails then were positioned such that the local streamline was tangent

to the sail surface at the trailing edge. This condition would allow for flow

attachment on the sails for the particulav wing angle of attack. Figures 5c and

5d show the wing beyond stall and with the flow favorably affected by the sails.

An arrangement of four sails (the most forward mounted vertically at mid chord,

the most rearward mounted horizontally, and equal angular increments between the

four) was most effective in maintaining the tip flow to high angles of attack.

•..• •T :"• :T • :• •-F!•'••,•~eb " .:• .,,-,.,. ..~........... ..... ...... ..

.1

This four-sail arrangement was also used with the CCW and USB configuration in the A

8- by 10-foot wind tunnel tests.

CIRCULATION CONTROL WING

Figures 6, 7, and 8 show the lift curves and drag polars obtained with the

aspect ratio 4 CCW configuration. The maximum lift coefficient obtained for this

configuration was 4.0, which was achieved with the model utilizing the family of

tip sails. The use of the wing tip fence and the tip sails enhanced the perform-

ance of the CCW. The improvement shown in both CL and CL while using the tipa Cmax

fence or sails is attributed to the delay in the tip stall brought about by these

devices. The tip sails proved to be somewhat more effective. In comparing common

values of C in Figures 7 and 8, the sails show a higher value of CL and delay

the stall to a higher angle at attack. The drag polars at Figures 6, 7, and 8

show the tip sails have little impact on the zero or low-lift drag, but these jsails definitely influence the induced drag that is deve)oped. The induced

drag is reduced over that of the plain tip configuration in both cases. IA comparison ot the induced drag factor K is presented in Figure 9. The in-

duced drag factor of the CCW with the tip sails for two representative values of C

shows a reduction of 30 to 35 percent over that ot the plain wing tip, and this

benefit is maintained into the high-lift region of interest. The pitching moments

obtained from the CCW model were obtained for wing alone (measured about the 1/4- .chord position). The large nose-down pitching moment typical ot these powered lift

configurations was apparent. The pitching moments were considerably more affected

by increases in the blowing coefficient than by angle-of-attack changes. The

pitching moments were also affected by the tip fence and sells. For similar

values of C the fence and sails produced the larger nose-down moments. I8 1

" ... . . .. . . ... -• " ";"-.• ! • . ,-

UPPER SURFACE BLOWING

Figure 10 shows various configurations of the USB model. A series of bench

testing was conducted on the USB model before entering the tunnel. Initial oper-

ation of the engine nozzle combination showed the exhaust flow did not adhere to

the trailing edge flap for the full extent of turning, but separated after a small

degree of turning. To alleviate this, an angled insert was placed in the nozzle to

deflect the flow more directly to the flap surface. The insert is shown in Figure

lOa, and the resulting attached flow, in the form of oil flow, is shown in Figure

lOb, The oil flow also served to determine the. spanwise extent of the flap to

which the exhaust would adhere. Outboard of this region, the double-slotted flaps

were exposed as shown in Figure lOc,

The lift and drag characteristics of the USB model with a 40-deg flap deflec-

tion are shown in Figures 11 and 12. The data were obtained with the aspect ratio

4 wing, and employed either the wing tip fence or the four tip sails. In both

instances, a CL of 4.8 was achieved, with the tip sails showing a slight improve-max

ment in the induced drag over that of the tip fence. The data of Figures 11 and 12

are the measured drag and, therefore, include the thrust component. This is the

case witb all the USB and CCW/USB configurations. The nose-down pitching moments

of this configuration are slightly more sevire than was the case with CCW and are

less affected by angle-of-attack changes,

Figure 13 shows a make-up of the lift contribution for this configuration.

The lower lift curve for each pair of curves shows the aerodynamic lift and includes

whatever augmentation is attained due to increased circulation resulting from the

j exhaust flow being turned by the trailing edge flap, The difference between the

lower lift curve and the upper curve then represents the thrust component for that

9

*1

S ..... . ......... .. • i A• . '•

particular power setting. The figure shows that the increment in lift augmentation

being attained by induced circulation due to thrust is decreasing as the thrust

is increasing; that is, the thrust contribution to the lift continues to increase

in proportion to the thrust, while the lift due to increased circulation may be

approaching a limit. The theoretical upper limit of lift due to circulation9 as a

function of aspect ratio and values from the current program are shown in Figure

14. With the thrust component removed from the USB data, the CCW more nearly

approaches the theoretical limit. The full range of the propulsion simulator was

not usable in this test program due to limitations in the house air supply; however,

the data of Figure 13 show the increment in circulation lift to be decreasing with

increasing thrust,

Figures 15 through 17 provide the longitudinal characteristics for the USB

model with a 60-deg flap deflection. The three arrangements evaluated were the

plain wing tip, tip sails, and tip fence. The maximum lift coefficient of 4.7 was

attained using the tip sails.

Oil flow studies of the three configurations are shown in Figure 18, The

model is at an angle of attack of 18 deg, The significant portion of the flow is

that about the wing tip. Figure 18a shows the plain wing tip with the flow sps- I

rating about half-way down the trailing-edge 60-deg flap section. The tip fence of

Figure igb has the flow separating just behind the slotted section of the flap.

Figure 18c shows the tip sails with the flow almost completely attached on the out-

board flap section. This favorable effect is reflected in the lift that was gen-

erated and the drag characteristics shown in Figures 15 through 17.

The associated induced drag factors of the plain tip and the tip sails

configurations are shown in Figure 19. Note that the thrust contribution has been

removed. The figure also shows the induced drag associated with this model while I

10 ]

., -.. .............I-.--•.

using no flaps. Of significance is that the difference in induced drag is more

favorable for the high-lift condition with a 60-deg flap setting than it is for the

no-flap or cruise condition.

The contribution to lift due to circulation and thrust for the USB model with

a 60-deg flap deflection is shown in Figure 20. The limiting effect ot lift aug-

mentation because of increased circulation is apparent with little augmentation

being attained beyond a thrust coefficient of 1.01. The maximum value of circu-

lation lift obtained with this configuration is 3.3, which is equivalent to the

lift obtained with the USB model and a 40-deg flap deflection, and falls right on

the value shown in Figure 14.

The USB aspect ratio 4 and 0-deg flap deflection data are shown in Figures 21

through 23, In this configuration, the 14 percent thick aupercrltical wing is

without the leading edge flap. The maximum lift coefficient is obtained with the

plain wing tip. The induced drag, however, benefits with the addition ot the tip

sails. For comparison, the model was equipped with a wing tip extension which in-

creased the aspect ratio to 5. The lift and drag characteristics for this config-

uration are provided in Figure 24. The induced drag factors for the "USB, AR M 4"

with and without tip sails and the "USB, AR w 5" with plain wing tip are shown in

Figure 25. The tip sails again show an improvement in the induced drag factor over

that for the plain wing with the same aspect ratio. The induced drag factor for

the aspect ratio 4 wing is equivalent to the plain tip for the aspect ratio 5 wing.

However, extrapolating the straight lines of Figure 25 back to zero lift gives the

zero lift drag which shows the penalty for using the sails. The effective aspect

ratio of the wing is increased at the expense of increased drag at other than the

design range of the particular sails.

ft

I

CIRCULATION CONTROL WING/UPPER SURFACE BLOWING

Figures 26 through 28 show the longitudinal aerodynamic characteristics of the

aspect ratio 4 CCW/USB configuration. The maximum lift coefficient of 5.1 was

obtained at the maximum attainable thrust coefficient, but at a moderate level of

C - 0.322 (Figure 28). The effectiveness of the tip fence and sails was not

measured on this configuration, therefore, all of the data pertain only

to the plain wing tip.

In comparing the CCW model with similar C P values of 0.29 with and without

tip sail (Figures 3 and 6), the maximum CL is shown to increase from 3.3 to 3.7 1when employing the sails. On this basis, the CCW/USB configuration would generate

a CL on the order of 5.6 if sails are used. The drag polars of Figures 26max

through 28 show a unique feature of the CCW/USB. At a given thrust level, an

increase in the momentum coefficient C causes the drag to increase as the thrust

is deflected more and more, due to the trailing edge blowing. The versatility of jthis feature makes possible the use of this concept in reversing thrust and in

vertical or hovering flight. To isolate the circulation lift on the CCW/USB

configuration, it is necessary to determine the degree of thrust vectoring that is

achieved with various levels of C• and engine ýhrust. Figure 29 shows the relation- Iship between the momentum coefficient CV and the 4 nternal duct pressure of the CCW.

Figure 30 then provides the exhaust turning angle corresponding to different thrust

levels and CCW duct pressure as determined under tunnel static conditions. For the

conditions being considered (C. - 0.322 giving PT " 60 in. Hg, (20.0 X 104 N/M2 )

and CT - 1.44 giving T - 59.6 lb (265.0 N)), the engine exhaust is deflected 89

deg. With the model at an angle of attack of 24 deg when a CL of 5.1 is

Imax

12 1

, .. ,- , .- . . ,.

generated, the lift due to circulation is 3.8. This is shown in Figure 31 along

with the highest values obtained in the test program for the CCW and USB models.

Considering that the CCW/USB was operating at a lower C,, value than that of the CCW

alone, and without the demonstrated benefits ot the tip sails, the CCW/USH shows

the best potential for generating the circulation lift closest to the theoretical

maximum.

A feature of the CCW/USB, as is the case with COW, is that an aircraft using

this combination is not required to contend with the high drag ot the extended

trailing edge flaps and deflected thrust during the takeoff roll, as is so with

USB. The procedure would entail using all thrust for acceleration until litt-ott,

when the CCW would be used to vector the engine thrust to some predetermined poei-

tion, thereby enhancing the circulation lift and adding the thrust component for

inmediate lift-off. The CCW/USB combination also has potential for vertical flight

because, as shown in Figure 30, the engine exhaust can be vectored up to 165 deg.

CONCLUSIONS

Low aspect ratio wings using powered-lift augmentation have the potential to

provide good STOL performance. The CCW/US8 configuration has the greatest poten-

tial in terms of lift augmentation and versatility for possible modes of operation.

The lift augmentation from the increased circulation due to the GCW trailing

edge and that of the deflected USB exhaust flow produced a CL of 5.1. The CCW/USB

model showed an increase of 43-percent in circulation lift (thrust components

Sremoved) at C - 0.332. This value of C was the maximum available when simul-

taneously operating the trailing edge blowing and the propulsion simulator because

of a limitation in supply air.

13

The USB configuration developed a CL of 4.7. With the thrust component

removed, this configuration demonstrated an increase of 28 percent in lift due

to circulation.

The COW configuration developed a CL of 4.0 with the lift due to circulation

being increased by 51-percent at C - 0.42.

The difference ir ., -entage increase in lift due to circulation, between the ICCW/USB and CCW alone, to clouded by the fact that the limited supply air restricted

the CCW/USB model to a lower C value. This was due to the need to operate both

the propulsion simulator and the trailinq edge blowing simultaneously off the same

source of supply air. The gains of the CCW and TBB separately suggest that, with)

an appropriate air supply, the CCW/USB would be even more effective than demon-

strated. Further, the CCW/USB combination has the versatility of thrust vector

control by a nonmechanical device to enhance its operational options. i

The use of wing tip sails reduced the induced drag factor by 30 to 35 percent Y

while allowing for a moderate increase in CL' Although the tip sails may not be

the best configuration for utilizing the tip vortex, results indicate that wing tip

devices are effective on low aspect ratio wings.

11

14

\.I

Figure 1 -Semispan Wing-Fuselage Model Configurations

NOMINAL CHORD SWEEP (dog)ASPECT RATIO TIP ROOT LI.E T.E, SEMISPAN

9 .40 in. 18.34 In. me a 1.91 It(21.34cm) (46.59cm) 218 0 (0,582m)

6.042 In, 18.34 In. 258 0 2.12 ft(16.31cm) (46.58cm) 258 0 (0,646m)

AR - 4

AR- 3

ROOT FENCE\

TUNNL FLORSIE IE 8f(.4384m) DIA.EL FSIDEVIEWSPLITTER PLATE

-R *0.0362C PLENUM

Figure lb -Circulation Control Wing Configuration

15

TANDEMMOUNTED1NG! NEt NE

EXHAUST DUCT

WINI

CHORDLINEENGINE PYLON

DUCT EXIT AREA j

Figure le - Upper Surface Blowing Configuration

gTANDEMMOUNTED I•'"ENGINEI INLE•T -

EXHAUST DUCT - N-'

F PANQ.E, .

• ENGINE PYLON I•• PLENUM

Figure id - Circulation Control Wing/Upper SurfaceBlowing Configuration

161

~~i

*.1 I

1 1.52 CWING TIP PLATE

WING ROOT PLATE

I Figure le -. Wing Tip and Wing Root Vence Configurations

17

Figure 2 -Semiapan Model in USE Configuration

Figure 3 -Samuipan. Model in CCW' Configuration with Wing Tip Fence

2. rCuMuO ACt BLANK-NOT J7LUs

Figure 4 -Semispan Model in CCW/USB Contiguration

21

4 3~~iEOIDNG PAds mLAw-maT FILMJ

Figure 5 - Supercritical Wing in Smoke Tunnel

Figure 5a - Wing Tip Sails

Figure 5b -Wing Tip Vortex (Plain Tip)

23

. . i- - -L

Figure 5 (Continued)

Figure 5c - Tip Flow at Stall

Figure Jl -'rip Vortex as Affected by Sails

25

M==.N1G PACK BLAMC-OT 1JIMJ~

.... . .....

Figure 6 - Longitudinal Characteristics of CCW Configurationwith Plain Wing Tip, AR 4, 6n 1" 40 Degrees

5.00

4,30 -

I JJ

I CL 3.00

Cm 0.07

1 2.50

2.00

1 1.50

I1.00S-10.00 0,00 10.00 20.00 30.00 40.00

a (deg)

, Figure 6a - Lift Curve

26

94

I'

Figure 6 (Continued) ,

4.001

3,50 1

3.00

CL 2,50I

1.50 C -0m 070

U!

1.00 I I I I L0.00 0.40 0.80 1.20 1.60 2.0", 2.40

CO

Figure 6b -Drag Polar J

2

I27

•iJ"3

Figure 7 - Longitudinal Characteristics of CCW Configurationwith Win8 Tip Fence, AR 4, 6 - 40 Degreesn

4,00

Cm 0 0.29

3.50 -

Cu- 0.,12

3.00

Cm 0.07

I (CL 2.50

!0I ,o

2.00

1.50

1 1.00 I I I .-10.00 0.00 10.00 20,00 30.00 40,00

I c (deg)Figure 7a -Lift Curve

.II, •• • . . ., . . + + •8

IFigure / (Continuud) I

5 ,00 ' I I

I4.501

4.00 1

3.60 1

CL 3.07

2.50 -

2,00 -

]1.50 -

1,000.00 0.40 0.80 1.20 1.60 2.00 2.40

Co

Figure 7h - Drag Polar i

29

: ":,!

IP

1I

Figure 8 - Longitudinal Characteristics of CCW Configurationwith Four Tip Sails, AR m 4, 5n 40 Degrees

4,50

4.00

1 3.50 "

CL

2.50

2.00

1.50I

1.00-10.00 0.00 10.00 20.00 30.00

I a (deg)

Figure 8a - Lift Curve

30

I3

)


5.00 - I' - I

4.60

4.00 -

A

3.501

CL 3.00 -

# w

II

2.50

2,00 - .

1.50 -

1.00- J0.00 0.40 0.o0 1,20 1.60 2.00 2.40

co

Figure 8b - Drag Polar

3.1

S, 1 i. ,

--II •

1.4 NO SAILS -

K. c- MORS

SAIS LK 0.06I

1 1.0 .o

S ~Co 0.8 C- 00

NO SAILS0.6 K -0.088

SAILSjK - 0,063

0.4 - 3

D CDo + KCL

0.2 -

0 I I I I3 2.0 4.0 6.0 8.0 10 12 14 16

CL

Figure 9 - Effect of Tip Sails on Induced Drag forCCW Configuration, AR - 4, 6 - 40 Degrees

I3I

II 3 2

Figure 1Oa - Nozzle Insert and Tip Saila,

6f - 40 Degrees

Figure lob - Plain Tip, Figure 10e - Outboard Double Slotted-f 60 Degrees Flaps, Tip Fence, 6 - 60 Degrees

Figure 10 - Oil Flow for USB Model, AR - 4, Static Tunnel Conditione

33

:4 •,.7. " ...

-e , l e innI

Figure 1.1 - Longitudinal Characteristice of USB Configurationwith Wing Tip Fence, AR - 4, f - 40 Degrees, 6n , 40 Degrees

5,00

CT - 1.4

4.50

i ,CT- 1,0

4.00

I

1 3.50

CT 0.59II CL 3.00 -

2.50I

2.00

1.10

1.00 .., I-10.00 0.00 10.00 20.00 30.00 40.00 50.00

01 (deg)

Figure lla - Lift Curve

35

I r ' 1MG PAM MAW-= ]MUM

Figure 11 (C~ontinued) .5.001

4.50 1r1.

TI4.00 CT1.

3.50

CT 0O.50

CL 3,00 1CI

1.00 II-0.40 0-00 0.40 0.80 1.20 1.60 2.00J

co

Figure Ilb - Drag Polar

36 1

Figure 12 - Longitudinal Characteristics of USB Configurationwith Four Tip Sails, R - 4, f - 40 Degrees, 6. W 40 Degrees

5,00

C T -1.4

4.50 T

C? -0.92

4.00

i 3.50

CL 3,00

2.50

1 2.00

Ii 1.50

I 1.00Ii

-10.00 M 0.00 10,00 20,00 30.00 40.00

a (deg)


1 37

,iI

S. ...... . . .- . •. .. .-..

I:!

Figure 12 (Continued) "

5,00 I I I

CT 1.4I

4.50

4, 300 1

I

0,03.50 1

1..3,00--25 I

-0.40 0.00 0 .40 0.60 1.20 1.60 2.00Co


38 1

I'3

i

5.0

4.5 00 0000

0

4.0

C 1. 1 0

30 * A0. --LJ ~4* ~ A

CL 2,5 A QQQ-0CO5~0

2,0 0

01.6

1.0

0.6o.:LI I IL i I.

5.0 10 15 20 25 30 36 40

a (deg)

Figure 13 Lift Components for USB Configurationwith Tip Sails, AR - 4, 8 - 40 Degrees, 65 n 40 Degrees

39

4-1141 1

-t0 uI

40ei

Figure 15 - Longitudinal Characteristics of USB Configuration withPlain Wing Tip, AR - 4, Sf f 60 Degrees, 6 - 40 Degrees

4.50 CT -1.39

CT 1.02

4.00 -

1 3.50

cT 2,07

S3.00

2.50I

2.00

II 1.50

iI 1,oo.0 I I I I

-10.00 0.00 10.00 20.00 30,00 40.00

I ca (deg)


I1 41

SII

1I

Figure 15 (Continued) J4,.50 " 1

C T 1.39

4 .00 C-T 1 .0 2 -

I3 .5 0 -

ST .5

3.00

CLI

2 .5 0 -

12.00

1.50

1.00- I I I I I0.00 0.40 0.80 1.20 1.60 2.00

Co


42 !

V..,/ ..... •• ...- '..p .••' .

Figure 16 - Longitudinal Characteristics of USB Configurationwith Four Tip Sails, M - 4, f - 60 Degrees, 6 - 40 Degrees

I n

5.00

4.50 CT - 1.42

CT. 0 1.03

4.00

3.50C- 0,57

CL 3.00

2.50

2,00

t 1.10-

1,00 -i-10,00 0.00 10.00 20.00 30.00

a (deg)Figure 16a - Lift Curve

43

• 1.

II


1.00 I I I

4.501.42

4.00 TI

3.50 -- ar05

CL 3,00-

II

2,50 -

I

1.50 - I

1.500

0.00 0.40 0.60 1.20 1.60 20i co

Figure 16b -Drag Polar I

44

Figure 17 - Longitudinal Tharacteriutics of USB Configurationwith Wing Tip Fence, AR - 4, S£ * 60 Degrees, 8n * 40 Degrees

5.00 I " I '

4.50CT, 1.,42

IC4. 00 a

B 3.50O

I/IICL 3.OO

1 2.50

5 2.00

I1.50

I ~ ~~~~1,001_I._ . I_

-10.00 10,00 20.00 30.00 40.00 50100

i (deg)


S I" 45

JA ... .....

l"igurL• J 7 (Con L inued)

CT 1.421

4.00 - .. .. 02

3.50 I

°"" IS0 C r 0 1,01

CL 3.00 I

i2.50 I

2,00 -

1.50 -

0.00 0.40 0,80 1.20 1.60 2.zo 2.40

CO


46

-V. , 1 .

Figure 18a - Plain Tip

Figure Abb - Wing Tip Fence lFiguro Lbc - Wing 'lip Sails

Figure 18 - Oil Flow for USE Configuration, AR - 4

af w 60 Degrems, Sn 40 Degrees, a * 18 Degrees

47

IleI1.4

*w. 0.701

1.2

I 1.0

CD 0,8

I

0.6 *t 0,6

f *O.734

0.4 -6f an 6 SAIL8 (4)

000 40i0 60 4 0

0.2 - 00 0

0 2 4 6 8 10

cL e

Figure 19 -Effect of Tip Sails on Induced Drag for USE Configuration, AR 4

1 49

PA aN-AtFL

4.0 00 *Thrust

.CT 1.4

pt30.,o -II - II'

G~ ~ C 0 '----"-

CL 2.5 C 7I

2.0

1.5

1.00

0.5

AI0 5.0 10 15 20 25 30 35

a (deg)

Figare 20 - Lift Components for USB Configuration, AR = 4,a•f = 60 Degrees, 6 r. 40 Degrees

0 n 30J

Figure 21 - Longitudinal Characteristics of USB Configurationwith Plain Wing Tip, AR 4, - 0 Degrees, n - 0 Degrees

f n

4.00 -1I

3,50

3 -CT- 1.43,00

20I 2.10

CT a 1.0

CL 2.00

CT " 0.53t1.50I

1 1,00

I1 0.50

-10.00 0.00 10.00 20.00 30.00 40.00 50.00


51

7._° _

I

Figure 21. (Continued) .

4.00

3.60-

3.00 0.• - cT 1 , 4

2,50

CL. 2.00 -

1,50 -- I

I

3,00 --

0.50

]C0 .001

-1.60 -1.20 -0.80 -0.40 -0.00 0.40 0,80c D

S~I

r Figure 21b -Drag PolarI

52

usa

11I• . o . o . L .. ,, , "; ,,IS. • -- .I.- --• , - . ... . . . .

II

Figure 22 - Longitudinal Characteristics of USB Configuration

with Wing Tip Fence, AR - 4, 6f - 0 Degrees, d " 0 Degrees

I 4,00

3.50I

1 3.00

i CT - 1.41

CL 2.00

1.50 -

C 1.00

0.50

0.00 I i I-10.00 0.00 o0.00 20.00 30.00 40.00 50.00

a (deg)


53

Ii,


4.004300 1T I

3,50 --.

I

3,0 1.]

2.50

CL 2.00 1"CT0,58 -

1.50 -

1.00

0,50 -- 1

0100-1.60 -1.20 -0,80 -0.40 -0.00 0.40 0.80

CO

Figure 22b - Drag Polar 3

54

1a

I

Figure 23 - Longitudinal Characteristics of USB Configuration

Swith Wing Tip Sails, AR - 4, e -0 Degrees, n 0 Degrees

4,00-

12.50 -

I

i 3.00

1.00-

0.50S1,040 -. ;

-10.00 0.00 10.00 20.00 30.00 40.00 50.00

a (deg)


55

Fig~ure 23 (Colintined)

3.501

2.501

CL 2.001

1.60

1,001

0.00 1-1.60 -1.20 -0.90 -0.40 -0.00 0.40 0.80

co


56

II

Figure W/ - Longitudinal Characteristics of USB Configuration%i tth Plain Wing Tip, M - 5, 6 f 0 Degrees, 6nd 0 Degrees

g 4o400 I I I

I 3.50 -

I

1 3.00 -

CT m 1,31

2.50 -

SC. - 0.94

.CL 2.00-

I CT -0.65

1.50 -

I CT 0231,00

1 0.50

I0.00 I I i I I

-10.00 0.00 10.00 20.00 30.00 40.00 50.00a (deg)


57

U I.

Figure. 24 (Continiued)

4.00

3.50 3

3.00

CT 1,32.50

CL 2,00 1Tw09

1.50 T-06

1.00 Iý02

0.50 1

0.001 r-1.60 -1.20 -0.80 -0.4-0 -0.00 ý 0.40 0.803

Figure 24b b rag Polar

58j

IIII 0.7

0 PLAIN TIP M 4I 0.6 r' SAILS MIR-4

0.8 PLAIN TIP AIR 5

00

0.5

0,4

CD

0.3

10.2 COUm %D + KCLII

I 0.1

I0 I . I I I I _0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

C2

LFigure 25 - Induced Drag Factor for USB Configuration,

af" 0 Degrees, a n 0 Degrees

I | tI

59,

-- , •,I

Fi"gure 26 - Longitudinal Characteristics of CCW/USB ConfiRuration, .AR - 4, CT 0 0.6, 6 - 40 Degrees

4.0 -- T T I ' I •4,

3.06

30 12.5 4

CL

2.0 2f I

1.0 1

I0,

-4 0 4 a 12 Is 20 24 26

a~ (dog)

Figure 26& - Lift Curve 1

60

II

i Figure 26 (Continued)

,CI 0.576

4.0

3.5

C0 CM -0.327

Cm /0.,172

C L 2 .0 --0

1 c,5

1 1.5 --

' I 1.0-

111-t I1 -0.8 -0.4 0 0.4 0.3 1,2 1.6 2.0

CD


4' 61.

"Ii

F'izure 27 - longitudinal Chnracteristics of CCW/USB Configuration,

0AR -4. CT , 1.19, 6n 40 Degrees

4.0 -I3.5- ;/1

2.0 1

3,5

I

3.01

-0.4 0 4 a 12 is 20 24 28

a (deg)Figure 27a - Lift Curve

2.02

I 0• I

0.5' ; ,,

I

I ~Figure 27 (Continued)

5.0 'Co. 0,572

w4.5 -

4.0 -

3.5cU 0.326S~~3.5 - : ~~

3.0 - Ci, 0.17

I ~CL

2.5B

I1.2.0

11.5

1,0I •0cu-0.0

1 0.5

-0.8 -0.4 0 0.4 0.8 1.2 1.6 2.0 2.4I'1 Co


63

( . -,• a, • I I, ' • . . .

Figtire 28 -Longitudinnl Characteristics of CCW/USB Configuration,AR -4, C T w 1.45, 6 n 40 Degrees

4.6

4,0 1

3.,5I

3.0

CL 2. -C

1.5 1

1.0

a (des)

Figure 28a - Lift CurveI

64j

IIII

I Figure 28 (Continued)

5.0

14,0• ••1 4.5

I4.0

3.0

I ,CL

2.5- #

I 2,0

I1.0

I!"i:'Figure 28b - Drag Polar

6I5

"I .

I

0.7 I

0,00.6 - I'0.5 -

0.4 -

0,3 -

0.2

0,1- 3

5 10 IS 20 25 30 35 40 45 50 55 60

pT (lb/i,•,2)

TDFigure 29 - Blowing Coefficient versus Duct Pressure for CCW/USB 1

6II

66

4 II

I

I

140 -

120T 496 lb

100 -T - 39.6 lb

.| • so -T - 72.6 :Lb

! soI 1 40

20-

II,

0 20 40 60 60 100 120

P (CCW TOTAL PRESSURE) (in. Hg)D T

i Figure 30 - CCW/USB Static Engine Thrust Turning

<I

I]

1- 4Il

10 NOIVIrMI I

68I

I

REFERENCES

1. Nichols, J.H., Jr., "Development or High Lift Devices for Application to

Advanced Navy AircrafL," DTNRSDC-80/058 (Apt 1980); also presented at Workshop on

V/STOL Aerodynamics, Naval Post Graduate School, Monterey, CA (16-18 May 1979).

2. Phelps, A.E., Ill, "Wind Tunnel Investigation of a Lwin Engine Straight-

J Wing Upper-Surface Blown Tet-Flap Configuration," NASA TN D-7778 (Jan 1975).

3. Sleeman, W.C., Jr., and W.C. Hoklweg. "Low Spead Wind Tunnel Investigation

I of a Four-Engine Upper Surface Blown Model Having a Swept Wing and Rectangular and

D-Shaped Exhaust Nozzles," NASA TN D8061 (Dec 1975).

* 4. Perry, B., III and G.C. Greene, "Wind-Tunnel Investigation of Aerodynamic

Loads on a Large-Scale Externally Blown Flap Model and Comparison with Theory,"

NASA RN D-7863 (Mar 1975).

5. Woodrey, R.W., et al., "An r<verimental Investigation of a Vectored

Engine Over-Wing Powered Lift Concept," AFFDL-TR-76-.92 (Sep 1976).

1 6. Englar, R.J. and R.A. Hemmerly, "Design of the Circulation Control Wing

STOL Demonstrator Aircraft," Paper 79-1842 presented at AIAA Aircraft Systems and

Technology Meeting, New York (20-22 Aug 1979).

* j7. Spillman, J.J. and J.E. Allen, "The Use of Wing Tip Sails to Reduce Vortex

Drag," Cranfield Institute cf Technology (Jun 1976).

1 8. McCormack, B.W., Jr., "Aerodynamic of V/STOL Flight,': Academic Press, New

York (1967), pp. 53-57.

69

~ • ,. . . . . . . . . .,

II

I

OTNSROC ISSUES THREE TYPES OF REPOt"S

1. DTNSR11C REPORTS, A FORMAL SERIES, CONTAIN INFORMATION OF PERMANENT TECIi-NICAL VALUE. THEY CARR•Y A CONSECUTIVE NUMERICAL IDENTIFICATION REGARDLESS OF

THEIR CLASSIFICATION OR THE ORIGINATING DEPARTMENT.

2. DEPARTMENTAL REPORTS, A SEMIFORMAL SERIES, CONTAIN INFURMATION OF A PRELIM-INARY, TEMPORARY, OR PROPRIETARY NATURE OR OF LIMITED INTEREST OR SIGNIFICANCE.THEY CARRY A DEPARTMENTAL ALPHANUMkRICAL IDENTIFICATION

3. TECHNICAL MEMORANDA, AN INFORMAL GENIES. CONTAIN TECHNICAL DOCUMENTATIONOF LIMITED USE AND INTEREST. TH4EY ARE PRIMARILY WORKING PAPERS INIENDED FOR IN-TERNAL. URE. THEY CARRY AN IDENTIFYING NUMBER WHICH INDICATES THEIR TYPE AND THENUMERICAL CODE OF THE ORIGINATING DEPARTMENT. ANY DISTRIBUTION OUTSIDE DTNSRDCMUST BE APPROVED BV THE HEAD OF THE ORIGINATING DEPARTMENT ON A CASE.BY-CASEBASIS.

I'ISI

jII

jul low - dticsecurity class, (ao thla topolt) unclassified dcj.a2sific"ation./oowng ca,...

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