Document
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FLIGHT INVESTIGATION OF
THE AERODYNAMIC PROPERTIES
OF AN OGEE WING
by L. Stewart Rolls, David G. Koenig,
and Fred J. Drinkwater H I
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Ames Research Center
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OL3007L NASA T N D-3071 FLIGHT INVESTIGATION O F THE AERODYNAMIC PROPERTIES O F AN OGEE WING By L. Stewart Rolls, David G. Koenig, and Fred J. Drinkwater I11 Ames Research Center Moffett Field, Calif.
N A T I O N A L A E R O N A U T I C S A N D S P A C E A D M I N I S T R A T I O N For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price $1.00 I FLIGHT INVESTIGATION O F THE AERODYNAMIC PROPERTIES O F AN O G E E WING By L. Stewart Rolls, David G. Koenig, and Fred J. Drinkwater I11 Ames Research Center SUMMARY The low-speed c h a r a c t e r i s t i c s of a delta-wing a i r c r a f t modified t o an Ogee plan form were i n v e s t i g a t e d i n f l i g h t and i n t h e Ames 40- by 8 0 - ~ o o t Wind Tunnel. The f l i g h t r e s u l t s showed t h e a i r c r a f t had good f l y i n g q u a l i t i e s with improved l a t e r a l - d i r e c t i o n a l c o n t r o l c h a r a c t e r i s t i c s . The f l i g h t c h a r a c t e r i s - t i c s of t h e a i r c r a f t were s u f f i c i e n t l y improved t h a t t h e p i l o t w a s w i l l i n g t o lower t h e approach speed 10 knots.
INTRODUCTION Supersonic t r a n s p o r t configurations t h a t employ fixed-geometry wings of low aspect r a t i o have been found t o provide performance competitive with t h a t of other designs. Some small-scale wind-tunnel t e s t s ( r e f . 1) have i n d i c a t e d t h a t one v a r i a t i o n of t h i s type of wing, t h e Ogee, e x h i b i t s b e t t e r low-speed o r landing c h a r a c t e r i s t i c s than some o t h e r plan forms of low aspect r a t i o .
These b e n e f i t s r e s u l t from a s t a b l e vortex flow which i s e s t a b l i s h e d over t h e wing by t h e high sweep angle a t t h e wing root of t h e Ogee p l a n form. This vortex system enables t h e wing t o develop higher l i f t a t angles of a t t a c k used f o r landing and take-off. To f u l l y document t h e c h a r a c t e r i s t i c s of t h e Ogee plan form, it w a s t e s t e d i n f l i g h t and i n a f u l l - s c a l e wind t u n n e l . The spe- c i f i c o b j e c t i v e o f t h e t e s t s w a s t o determine whether t h e s e b e n e f i t s of vortex flow are obtainable i n f l i g h t and whether f l i g h t maneuvers would destroy t h e vortex system s o t h a t t h e p i l o t could not u t i l i z e t h e s t a t i c l i f t c a p a b i l i t i e s of t h e wing.
For t h i s i n v e s t i g a t i o n , t h e d e l t a wing of a Douglas F5D-l a i r c r a f t was modified t o incorporate a n Ogee wing plan form. This modification w a s first t e s t e d i n t h e Ames 40- by 80-Foot Wind Tunnel t o determine t h e s t a t i c aerody- namic d a t a before t h e configuration was f l i g h t t e s t e d . Following t h e t u n n e l t e s t s t h e modifications were made flight-worthy and t h e low-speed f l i g h t char- a c t e r i s t i c s w e r e i n v e s t i g a t e d .
This r e p o r t describes t h e flight-measured s t a t i c and dynamic aerodynamic c h a r a c t e r i s t i c s of t h e t e s t a i r p l a n e with t h e Ogee wing. Some of t h e r e s u l t s of t h e 40- by 80-foot wind t u n n e l tests are compared with t h e f l i g h t d a t a where a p p l i c a b l e .
NOTATION drag
drag c o e f f i c i e n t , -
qs l i f t
l i f t c o e f f i c i e n t , -
qs dynamic pressure, lb/sq f t wing area, sq f t angle of a t t a c k , deg angle of s i d e s l i p , deg elevon d e f l e c t i o n , deg rudder d e f l e c t i o n , deg p i t c h i n g v e l o c i t y , radians/sec r o l l i n g v e l o c i t y , radians/sec yawing v e l o c i t y , radians/sec DESCRIPTION Test Airplane The a i r c r a f t used i n t h i s i n v e s t i g a t i o n w a s t h e Douglas F5D-1, a single-place, jet-propelled, delta-wing f i g h t e r . The highly swept d e l t a plan form of t h i s a i r c r a f t served as a convenient base f o r t h e modifications required t o produce t h e Ogee plan form. A photograph of t h e F3D-1 as modified f o r t h e s e t e s t s i s shown i n f i g u r e 1. Figure 2 p r e s e n t s a two-view drawing of t h e airplane; p e r t i n e n t dimensions a r e presented i n t a b l e I and i n f i g u r e 3.
The plan form f o r t h e b a s i c F5D-l i s shown on f i g u r e 2 f o r comparison. The wing extension w a s constructed of wood which w a s attached t o t h e o r i g i n a l wing with metal sheets and g l a s s f i b e r m a t e r i a l .
25,000 t o The weight of t h e a i r c r a f t during t h e s e f l i g h t s varied from 21,000 pounds and t h e c e n t e r of g r a v i t y w a s 32 percent of t h e mean aerodynamic chord. S t r u c t u r a l l i m i t a t i o n s prevented b a l l a s t i n g t o a more forward center- of-gravity p o s i t i o n .
INSTRUMENTATION Recording instruments were i n s t a l l e d t o record simultaneously measurements of airspeed, a l t i t u d e , normal and l o n g i t u d i n a l a c c e l e r a t i o n , angles of a t t a c k and s i d e s l i p , and t a i l - p i p e t o t a l pressure. Control p o s i t i o n transducers were mounted a t t h e c o n t r o l surfaces, and angular turnmeters were i n s t a l l e d t o doc- ument t h e t r i m and s t a b i l i t y c h a r a c t e r i s t i c s and unsteady phenomena.
To mini- mize t h e e r r o r s i n t h e airspeed and angle-of-attack measuring systems, a boom 10 f e e t long w a s mounted on t h e nose of t h e a i r c r a f t . This i n s t a l l a t i o n was not c a l i b r a t e d , but a similar i n s t a l l a t i o n used i n t h e t e s t s described i n r e f - erence 2 indicated t h e e r r o r s t o be s m a l l .
A motion p i c t u r e camera mounted on t h e v e r t i c a l t a i l photographed t h e wing t u f t s and vortex p a t t e r n s .
RESULTS AND DISCUSSION Longitudinal C h a r a c t e r i s t i c s The s t a t i c l o n g i t u d i n a l aerodynamic c h a r a c t e r i s t i c s of t h e t e s t configuration, as measured during t h i s f l i g h t i n v e s t i g a t i o n , a r e shown i n f i g - ures 4, 5 , and 6 i n t h e form of angle of a t t a c k , drag c o e f f i c i e n t , and pitching-moment v a r i a t i o n with l i f t c o e f f i c i e n t . For comparison, t h e 40- by 80-foot wind-tunnel d a t a a r e p l o t t e d on t h e appropriate f i g u r e s . The varia- t i o n s of angle of a t t a c k and drag c o e f f i c i e n t with l i f t c o e f f i c i e n t f o r t h e
gear-up configuration a r e presented i n f i g u r e 4, and f o r t h e gear-down config-
u r a t i o n i n f i g u r e 5 . These d a t a were obtained i n steady f l i g h t a t d i f f e r e n t airspeeds a t t h e lower angles of a t t a c k , and during continuous maneuvers with slowly decreasing airspeed a t t h e higher angles of a t t a c k . The equations f o r determining l i f t c o e f f i c i e n t , drag c o e f f i c i e n t , and t h r u s t a r e described i n reference 3. The t e s t s t o measure t h e s e q u a n t i t i e s were conducted a t an a l t i - tude of about 10,000 f e e t .
Pitching-moment v a r i a t i o n s with l i f t c o e f f i c i e n t a r e presented i n f i g u r e 6. The f l i g h t data were obtained from t h e measured v a r i a t i o n of longi- t u d i n a l c o n t r o l d e f l e c t i o n with airspeed and were converted t o p i t c h i n g moment by use of t h e value of c o n t r o l e f f e c t i v e n e s s as measured i n t h e wind-tunnel t e s t s . The data on t h i s f i g u r e i n d i c a t e t h a t f o r t h e t e s t center-of-gravity l o c a t i o n of 32 percent of t h e mean aerodynamic chord, t h e s t a t i c l o n g i t u d i n a l s t a b i l i t y was n e a r l y n e u t r a l . The mild i n s t a b i l i t y shown i n t h i s f i g u r e at a l i f t c o e f f i c i e n t of about 0.5 w a s a l s o measured during t h e wind-tunnel t e s t s and was apparent t o t h e p i l o t during f l i g h t t e s t s . The magnitude of t h i s e f f e c t was s m a l l and as shown i n f i g u r e 6(b) w a s of t h e order of lo change i n c o n t r o l surface d e f l e c t i o n and did not cause t h e p i l o t s t o l i m i t t h e f l i g h t envelope of t h e v e h i c l e .
F l i g h t s a t high angles of a t t a c k a r e characterized by s l i g h t b u f f e t t i n g , and although t h i s disturbance does not increase s i g n i f i c a n t l y as angle of a t t a c k i s increased above l 5 O , it i s considered t o i n d i c a t e t h e l i m i t i n g angle 1 1 1 I I I 111 II 1 1 1 - 1 1 1 1 . 1 - 1 1 1 f o r landing approach. The p i l o t s r e p o r t t h a t during f l i g h t a t high angles of a t t a c k , t h e primary problem i s c o n t r o l l i n g p i t c h a t t i t u d e , and t h a t s m a l l ele- vator inputs a r e continually required t o keep t h e a i r c r a f t from wandering. The increased l o n g i t u d i n a l c o n t r o l a c t i v i t y r e s u l t s from t h e nearly n e u t r a l s t a b i l - i t y of t h e a i r c r a f t a t t h e center-of-gravity l o c a t i o n flown. The shaded a r e a on f i g u r e 6 ( b ) a t t h e high angles of a t t a c k illustrates t h e magnitude of t h i s c o n t r o l a c t i v i t y .
Lateral-Directional C h a r a c t e r i s t i c s The s t a t i c d i r e c t i o n a l s t a b i l i t y was i n v e s t i g a t e d a t four airspeeds, 180, 130, 120, and 100 knots, corresponding r e s p e c t i v e l y t o angles of a t t a c k of 7', 1 2 ' , l 5 ' , and 2 3 O , and t h e r e s u l t s a r e presented i n figure 7. It had been speculated t h a t nonlinear s t a b i l i t y c h a r a c t e r i s t i c s might r e s u l t i n s i d e s l i p s from t h e vortex changing l o c a t i o n with r e s p e c t t o t h e wing leading edge. As shown i n f i g u r e 7, within t h e s i d e s l i p angles which could be obtained i n f l i g h t , t h e v a r i a t i o n s of d i f f e r e n t i a l elevon angle and rudder angle with steady s i d e s l i p angle f o r t h e gear-up and gear-down configurations are indi- cated generally t o be smooth and l i n e a r f o r t h e lower angles of a t t a c k . Some n o n l i n e a r i t y i n t h e dihedral e f f e c t i s becoming evident a t t h e t e s t angle of a t t a c k of 15' ( f i g . 7 ( b ) ) , but t h e magnitude shown d i d not evoke any c r i t i c a l comments from t h e p i l o t .
The a i r c r a f t and c o n t r o l surface motions during a r a p i d rudder r e l e a s e maneuver from maximum l e f t s i d e s l i p angle of t h e two lowest airspeeds a r e pre- sented i n f i g u r e s 8 and 9. These d a t a i n d i c a t e p o s i t i v e d i r e c t i o n a l damping.
These data, and data from s i m i l a r rudder r e l e a s e s , have been analyzed, and t h e period and damping a r e presented i n f i g u r e 10. The d a t a on t h i s f i g u r e show only a minor change i n damping c h a r a c t e r i s t i c s f o r angles of a t t a c k up t o approximately 24'.
The p i l o t f e l t t h a t t h e d i r e c t i o n a l s t a b i l i t y and c o n t r o l c h a r a c t e r i s t i c s superior to those of any delta-wing a i r c r a f t he at high angles of a t t a c k w e r e The a i r c r a f t exhibited no tendency t o develop abrupt had previously flown.
changes i n s t a b i l i t y and c o n t r o l .
Vortex C h a r a c t e r i s t i c s The vortex system can, under c e n t a i n atmospheric conditions, produce v i s i b l e condensation trails over t h e wing. Figure 1 1 shows t h e vortex, photo- graphed from t h e chase a i r c r a f t during a landing approach. It w a s not possi- b l e t o document t h e vortex c h a r a c t e r i s t i c s completely e i t h e r with t h e camera s o some of t h e information about t h e on t h e a i r c r a f t o r i n t h e chase a i r c r a f t , vortex behavior was obtained from t h e v i s u a l observations of t h e p i l o t s of both a i r c r a f t . The c h a r a c t e r i s t i c s of t h e vortex, both observed and photo- graphed, agree with t h e vortex behavior measured during t h e water t u n n e l t e s t s on an Ogee plan form described i n reference 4 regarding t h e changes due t o angle-of-attack and angle-of-sideslip v a r i a t i o n s . A s e t of sketches of t h e derived from photo- t u f t p a t t e r n s over t h e wing a t various angles of a t t a c k , a r e presented i n f i g u r e 12. The graphs taken by t h e tail-mounted camera, first t h r e e sketches show t h e increase i n t h e a r e a of unsteady flow as t h e The two sketches a t angle of a t t a c k changes from 7 . 5 O t o 1 5 ' and then t o 1 8 ' .
18O angle of a t t a c k are included t o show t h e v a r i a t i o n i n t u f t p a t t e r n s i n f l i g h t during t h e onset of mild b u f f e t t i n g and i n d i c a t e an increase i n t h e area of unsteady flow i n f i g u r e 1 2 ( d ) . Since changes i n t u f t p a t t e r n s between f i g u r e s l2(c) and 12(d) occurred i n about 0.3 second and were continually changing, it was reasoned t h a t flow changes over t h e outboard section of t h e wing might be one of t h e causes f o r t h e b u f f e t t i n g disturbance previously noted a t angles of a t t a c k g r e a t e r t h a n 1 - 5 ' . It i s a l s o possible t h a t some of t h i s disturbance i s caused by t h e e f f e c t of t h e vortex flow on t h e v e r t i c a l t a i l . The p i l o t o f t h e chase a i r c r a f t observed t h a t during f l i g h t s a t t h e s e angles t h e vortex appears t o be high o f f t h e wing and flows t o an area near t h e t a i l .
Comparison With Other Data A comparison of t h e c h a r a c t e r i s t i c s of t h e Ogee wing with t h e c h a r a c t e r i s t i c s of t h e d e l t a wing on t h e b a s i c F 5 S l a i r c r a f t should i n d i c a t e t h e effectiveness of t h e vortex flow i n maintaining favorable flow p a t t e r n s However, no f l i g h t d a t a a r e a v a i l a b l e over t h e wing at high angles of a t t a c k .
f o r t h i s airspeed range. It i s t h e r e f o r e necessary t o r e l y on t h e opinion of t h e p i l o t s as t o how t h e c h a r a c t e r i s t i c s of t h e a i r c r a f t with t h e Ogee wing compare with those of t h e b a s i c a i r c r a f t . I n carrier-type landings, t h e landing-approach speed of t h e b a s i c a i r c r a f t i s l i m i t e d by t h e d e t e r i o r a t i o n i n l a t e r a l - d i r e c t i o n a l c h a r a c t e r i s t i c s , evidenced l a r g e l y by low damping and high yaw angles induced by l a t e r a l - c o n t r o l inputs. The p i l o t s f e l t t h a t t h e l a t e r a l - d i r e c t i o n a l c h a r a c t e r i s t i c s were much improved f o r t h e a i r c r a f t with t h e Ogee wing and permitted a reduction i n t h e landing-approach speed of approximately 10 knots. The approach speed of t h e a i r c r a f t with t h e Ogee wing i s l i m i t e d by poor f l i g h t - p a t h c o n t r o l caused by l o n g i t u d i n a l i n s t a b i l i t y and by t h e r a p i d increase i n t h e power required with decreasing f l i g h t speed.
CONCLUDING REMARKS F l i g h t t e s t s of a delta-wing a i r c r a f t modified t o incorporate an Ogee wing plan form indicated t h a t over t h e range of angles of a t t a c k and s i d e s l i p flown, t h e vortex produced s t a b l e l i f t c h a r a c t e r i s t i c s . I n t h e opinion of t h e p i l o t t h e modified a i r c r a f t has improved l a t e r a l - d i r e c t i o n a l c o n t r o l and damp- i n g c h a r a c t e r i s t i c s . A t high angles of a t t a c k , g r e a t e r t h a n about l 5 ' , a slight lateral unsteadiness w a s noted by t h e p i l o t and, although it did not increase s i g n i f i c a n t l y a t higher angles of a t t a c k , it w a s considered an indi- c a t i o n of t h e l i m i t i n g angle f o r landing approach. The l a t e r a l - d i r e c t i o n a l f l y i n g q u a l i t i e s of t h e a i r c r a f t with t h e Ogee wing were s u f f i c i e n t l y improved t o permit a 10-knot reduction i n approach speed.
Ames Research Center National Aeronautics and Space Administration Moffett F i e l d , Calif., Sept. 2, 1965 REFERENCES 1. Spence, A.; and Smith, J. H. B.: Some Aspects of the Low-Speed and Supersonic Aerodynamics of Lifting Slender Wings. Proceedings of the
International Council of the Aeronautical Sciences, Third Congress -
stockholm, 1962, pp. 553-567.
2. White, Maurice D.; and Innis, Robert C . : A Flight Investigation of the Low-Speed Handling Qualities of a Tailless Delta-Wing Fighter Airplane.
NASA MEMO L15-59AY 1959.
3. R o l l s , L. Stewart; and Wingrove, Rodney C . : An Investigation of the Drag
Characteristics of a Tailless Delta-Wing Airplane in Flight, Including Comparison With Wind-Tunnel Data.
NASA MEMO io-8-58~, 1958.
4. Werl6, Henri; and Fiant, Claude: Water-Tunnel Visualization of the Flow
Around the Model of a "Concorde"-Type Airplane.
La Recherche Aerospa- tiale No. 102, September-October 1964, pp. 3-19.
TABU 1.- DIMENSIONAL DA,TA F O R THE F5D-1 AIRPLANE WITH AN OGZE PLAN-FORM WING - Wing
Area, sq f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 661
S p a n , f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.5
A s p e c t r a t i o . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.70
Mean aerodynamic chord, f t . . . . . . . . . . . . . . . . . . . . . 22.59
Incidence at r o o t , deg . . . . . . . . . . . . . . . . . . . . . . . 0
Geometric t w i s t , deg . . . . . . . . . . . . . . . . . . . . . . . . 0
Sweep
Leading edge a t r o o t , deg . . . . . . . . . . . . . . . . . . . . . 77
Leading edge, minimum, deg . . . . . . . . . . . . . . . . . . . . 33.8
Elevon
Area aft o f hinge l i n e (one s i d e ) , sq f t . . . . . . . . . . . . . . 24.26
S p a n , f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.79
Inboard elevon (trimmer) Area a f t of hinge l i n e (one s i d e ) , sq f t . . . . . . . . . . . . . .
9.04
Span, f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.58
V e r t i c a l t a i l
Area, sq f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69.87
Span, f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.46
Sweep of 25-percent chord l i n e , deg . . . . . . . . . . . . . . . . . 48.22
Rudder
Area a f t of hinge l i n e , sq f t . . . . . . . . . . . . . . . . . . . . 9 -25
S p a n , f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2s
Fuselage
Length, f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.83
M a x i m u m depth, ft . . . . . . . . . . . . . . . . . . . . . . . . . . 4.75
M a x i m u m width, f t . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7; ~.
I I 1111111111 I 111, ..I 1,111.. I, I,,, I I..,.. 1,1-.- ,,,_.I I --.-.__
A-32660-4 Figure 1.- Photograph of t h e t e s t a i r c r a f t i n f l i g h t .
\D Basic F5D-I - _- . . -
-
.I
Figure 2.- Two-view sketch of t e s t a i r p l a n e .
Engine inlet (ref.)
Wing leading edge-duct intersection x = 5 3 y = 103.5
b
Inflection point
xi
-- Section A-A L e a d i n g edge .3226
Y = 475.50 - 100 [ 2290 - 12.771
x -21 T r a i l i n g edge
y = 426.80 + , 3 0 3 2 2 ~
Figure 3 .- Details of Ogee plan form.
Figure 4.- Variation of angle of a t t a c k and drag c o e f f i c i e n t with l i f t coefficient; gear up.
L D Figure 5.- Variation of angle of attack and drag coefficient with lift coefficient; gear down.
F I ight test
----
4 0 X 80 wind tunnel
I .o
.8 $6 .4 .2
4 0 - .02 -.04 0
UP P i t c h i n g - moment c o e f f i c i e n t E l e v o n d e f l e c t i o n , deg about .32 mean aerodynamic chord.
(a) Pitching moment. (b) Elevon angle.
Figure 6.- Pitching-moment characteristics in landing-approach condition.
l o I
I O '
Vi + c 0 e 180 k n o t s .- E 0 ,-I30 knots A v 100 k n o t s 2 0 I O m Q) U
G o
M I O 2 0 c .c a -I 8 4 4 12 l 2 L e f t a Right ( a ) Gear up.
Figure 7.- Variation o f rudder and d i f f e r e n t i a l elevon angles with steady s i d e s l i p .
I
~ 3 0 Q
I Vi
+ =s! 70 r 0 z 180 knots 0, .- CL 0 c 130 knots % 12"
0 s 120 knots 15"
2 0 - - ..
I O I W -0
%
-
c 0
- 6
a m -_
'g
c Y- a l -I
-- I
4 8 Right L e f t (b) Gear down.
Figure 7 .- Concluded.
. . . ~ ._.. , , .
2 4 6 8 I O t, sec Figure 8.- Time h i s t o r y of a r e t u r n from maximum right sidesli-p at 120 k n o t s .
Time h i s t o r y of a r e t u r n from maximum right sideslip a t 100 knots.
Figure 9.-
1 8 4 8 12 16 20 24 a , deg Figure 10.- Directional damping characteristics as a function of angle of attack.
I [u A-33500-2 Figure 11.- Photograph o f t h e v i s i b l e vortex system.
I
I Steady t u f t d Unsteady tuft
I
L!
( c ) a = 18" ( d ) a = 18" Figure 12.- Tuft patterns at various angles of attack, zero sideslip.
NASA-Langley, 1965 A-2192 “ T h e aeronautical and space activities of the United States shall be conducted so as t o contribute . . . to the expansjon of human knowl- edge of phenomena in the atmosphere and space. The Administsation shall provide f o r the widest practicable and appropriate dissemination of information concerning its actisities and the results thereof .” -NATIONAL AERONAUTICS A N D S P A C E ACT OF 1958
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