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TECHNICAL MEMORANDUM X-441

STABILITY AND CONTROL CHARACTERISTICS AT A MACH NUMBER

OF 2.01 OF A SUPERSONIC VTOL AIRPLANE MODEL HAVING

A BROAD FUSELAGE AND SMALL DELTA WINGS

By C orneli us Driver and M. Leroy Spearman

Langley Research Center Langley Field, Va. ,..--_____ ~ __ _1. _ ____,

XEROX $

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CLASSlFlED DOC',MENT - TITL" lW:...ASSlnEt' L..-~---~----..------"

This matl...rial :': mlains Luormation affecting the national defense Of the United Stah!S Within the meaning of the espionage laws. Title lB, U.S . C., Sees. 793 and 794, the transmission or r~velation .;)fwhli'~h in any maruler l( an unauthQrized person Is pr Jhlblled by law.

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

WASHINGTON February 1961

CON FI DENTIAL

https://ntrs.nasa.gov/search.jsp?R=19630006264 2018-06-14T01:01:41+00:00Z

. °-

CONFIDENTIAL

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

TECHNICAL MEMORANDUM X-441

STABILITY AND CONTROL CHARACTERISTICS AT A MACH NUMBER

OF 2.O1 OF A SUPERSONIC VTOL AIRPLANE MODEL HAVING

A BROAD FUSELAGE AND SMALL DELTA WINGS*

By Cornelius Driver and M. Leroy Spearman

SUMMARY

An investigation has been conducted in the Langley 4- by 4-foot

supersonic pressure tunnel at a Mach number of 2.01 to determine the

stability and control characteristics of a model representative of a

supersonic vertical-take-off-and-landing airplane. The model had a

broad fuselagep small delta wings, and twin vertical tails.

The results indicated that the body alone provides a reasonably

high lift-curve slope and a maximum value of lift-drag ratio of about 4.

This value was increased to about 5.2 by the addition of the wings. The

complete configuration indicated a positive value of pitching moment

at zero lift such that positive deflections of the elevator would be

required for trimming in the lower lift range. However, because of a

reduction in stability at higher lifts, a slight forward movement of

the center of gravity may be necessary.

The configuration displayed an initially low value of directional

stability that decreased rapidly with increasing angle of attack until

directional instability occurred above an angle of 6° . in addition, the

configuration had a positive dihedral effect that increased with increasing

angle of attack.

INTRODUCTION

Among the manned aircraft currently being proposed are those that

combine the features of supersonic operation with the ability to take

off and land vertically (VTOL). Some of the configurations being con-

sidered make use of lifting fans in order to achieve the VTOL capability.

If these fans are installed in the body, the result may be a rather broad

*Title, Unclassified.

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2 CONFIDENTIAL

flat-type fuselage that might be expected to have a pronounced effecton the aerodynamic characteristics of the vehicle. Accordingly, aninvestigation has been undertaken in the Langley 4- by 4-foot supersonicpressure tunnel to determine the aerodynamic characteristics at a Machnumberof 2.01 of a model representative of a supersonic VTOLairplanehaving a broad fuselage, small delta wings, and twin vertical tails. Theresults of the investigation, together with a limited analysis, are pre-sented herein.

SYMBOLS

All data presented herein are referred to the body system of axesexcept the lift and drag data which are referred to the stability systemof axes. The momentreference point is at a longitudinal station corre-sponding to 65.3_ percent of the body length (40 percent wing meanaero-dynamic chord).

b wing span, 1.77 ft

CD drag coefficient_ DragqS

CL

Cy

Cy6

lift coefficient, LiftqS

side-force coefficient,

side-force parameter

Side force

qS

C

Ct_

Cm

rolling-moment coefficient,

effective-dihedral parameter

Rolling moment

qSb

pitching-moment coefficient, Pitching moment

qS_

Cn yawing-moment coefficient, Yawing moment

qSb

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Cn[

c

q

S

g.

ge

gr

directional-stability parameter

local chord, ft

wing mean aerodynamic chord, 1.08 ft

free-stream dynamic pressure, ib/sq ft

wing area, 1.488 sq ft

angle of attack, deg

angle of sideslip, deg

elevator deflection, deg

rudder deflection, deg

Subscripts:

L left

R right

Model components:

B body

V vertical tail

W wing

MODEL AND APPARATUS

Details of the model are shown in figure i and the geometric charac-

teristics are given in table I. The model was constructed in such a way

that the wing and tail panels could be removed and the deflection angles

of the elevator and rudder could be changed. Both a plane and a cambered

wing were investigated. The body was designed to provide for an internal

flow system composed of twin horizontal-ramp inlets on the sides of the

body that were ducted to six simulated jet exits side by side at the base

of the body. No attempt was made to simulate jet exits that might be

required for VTOL, however. With but one exception, all tests were made

with O.lO-inch-wide transition strips of No. 80 carborundum grains affixed

2 inches behind the fuselage nose and at the lO-percent-chord stations of

the wing and tail surfaces.

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T_

--v

4 CONF IDENTIAL

The model was mounted in the tunnel on a remote-controlled rotary

sting. Six-component force and moment measurements were made throughthe use of an internal strain-gage balance.

TESTS, CORRECTIONS, AND ACCURACY

The tests were made in the Langley 4- by 4-foot supersonic pressuretunnel with the following test conditions:

Mach number ........................... 2.01Stagnation temperature, OF ................... ii0

Stagnation pressure, ib/sq in .................. i0

Reynolds number, based on _ ................ 2.6 x 106

The stagnation dewpoint was maintained sufficiently low (-25 o F or

less) so that no condensation effects were encountered in the testsection.

Tests were made for an angle-of-attack range of about -7° to 16°

at _ _ 0° and for an angle-of-sideslip range of about -8° to 12 ° at

= -0.5 ° and about -8° to i° at _ = 4.8 °, 9.3 °, and 13.8 °.

The angles of attack and sideslip were corrected for deflection

of the balance and sting under load. The drag data have been corrected

for the effects of internal flow, base pressure, and balance chamberpressure.

The estimated accuracy of the individual measured quantities is asfollows:

CL .............................. ±0.0004

CD .............................. ±0.0007

Cm .............................. ±0.0004Cn .............................. ±0.0001

CZ .............................. ±0.0003

Cy .............................. ±0.0007

_, deg ............................. ±0.2

_,deg ............................. ±0.2

The control deflections were accurate to within +0.i °.

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DISCUSSION

The addition of transition strips to the complete configuration withthe camberedwing (fig. 2) had little effect on the aerodynamic charac-teristics in pitch other than to cause a slight increase in drag with anattendant decrease in lift-drag ratio. All the other results presentedherein were obtained with transition fixed.

The primary effects of cambering the wing (fig. 3) were to cause apositive increment in Cm, to increase the minimumvalue of CD, and toreduce the drag due to lift. Becauseof the compensating changes inminimumdrag and drag due to lift_ there was little effect of wing camberon the maximumvalue of L/D. All other results presented herein wereobtained with the cambered-wingarrangement.

The results for various combinations of model components (fig. 4)indicate that the body alone provides a reasonably high slope of thelift curve and a maximumvalue of L/D of about 4. The addition ofthe wing causes an increase in lift-curve slope and in minimumdragbut a decrease in drag due to lift so that the maximumvalue of L/Dis increased to about 5.2. The results indicate a positive value ofCm at CL = 0 for the configuration either with or without the wing.This effect is probably caused by lifting pressures induced over thecanopy. The complete configuration indicates a decrease in stabilitywith increasing lift and, in fact, becomesabout neutrally stable in thelift-coefficient range from about 0.2 to 0.5.

Deflection of the elevator (fig. 5) provides reasonably linearincrements of Cm. Becauseof the initial positive value of Cm atCL = O, positive deflections of the elevator would be required for trimin the lower lift range. Such an arrangement might result in a slightincrease in L/D due to trimming since the control deflection requiredfor trimming would provide a positive lift increment. However, becauseof the neutrally stable region at higher lifts, a slight forward move-ment of the center of gravity may be necessary.

The effects of various combinations of model componentson thesideslip characteristics are presented in figure 6 for several anglesof attack. The complete configuration displays a low level of directionalstability throughout the angle-of-attack range as a result, primarily, ofthe large instability of the body alone. In addition to the initiallylow directional stability, the variation of Cn with _ is nonlinearand does in fact reverse with increasing sideslip (fig. 6(a)). Thepresence of the wing provides a slight stabilizing increment in yawingmoment.

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6 CONFIDENTIAL

The addition of both the wing and the tail provides a positivedihedral effect. With increasing angle of attack the contribution torolling momentprovided by the wing increases while that provided bythe tail decreases slightly but the overall effect is a progressiveincrease in effective dihedral for the complete configuration.

The effects of angle of attack on the sideslip characteristics ofthe complete model are shownmore clearly in figure 7 and the variationsof sideslip derivatives with angle of attack for the model with and with-out the vertical tail are presented in figure 8. The directional stabilityCn_ decreases rapidly with increasing angle of attack so that directionalinstability occurs above _ = 6° . This decrease in Cn_ is due in partto the increasing instability of the wing-body combination and in partto a loss in vertical-tall effectiveness. The increasing instability ofthe wing body is characteristic of bodies having far rearward momentcenters, whereas the loss in tail effectiveness maybe caused by adisturbance created by the inlet lips.

The results also indicate a rapid increase in positive effectivedihedral __(-Cz_) with increasing angle of attack. This increase ineffective dihedral combinedwith the decrease in Cn_ suggests the needfor vertical fin area behind and below the center of moments.

Limited studies of the directional control characteristics (fig. 9)indicate that with increasing _ there is a progressive decrease inthe ability of the rudder to produce Cn. Deflection of the rudderalso causes a substantial increment in adverse rolling-moment coefficientthat increases with increasing _. Deflection of the elevator had littleeffect on the directional control characteristics.

The roll control characteristics (fig. i0) were investigated fordifferential deflections of ±7.5° with elevator deflections of 0oand -25° and for both cases the increment of rolling-moment coefficientobtained was essentially constant with angle of attack. The roll effec-tiveness was considerably reduced by deflecting the elevator to -25°probably because of a decrease in lift effectiveness of the left elevatorat the high total deflection of -32.5 ° .

CONCLUDINGRENARKS

An investigation has been conducted in the Langley 4- by 4-foot

supersonic pressure tunnel at a Mach number of 2.01 to determine the

stability and control characteristics of a model representative of a

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.t --

CONF IDENT IAL 7

supersonic VTOL airplane. The model had a broad fuselage, small delta

wings, and twin vertical tails.

The results indicated that the body alone provides a reasonably

high lift-curve slope and a maximum value of lift-drag ratio of about 4.

This value was increased to about 5.2 by the addition of the wings. The

complete configuration indicated a positive value of pitching moment at

zero lift such that positive deflections of the elevator would be required

for trimming in the lower lift range. However, because of a reduction in

stability at higher lifts, a slight forward movement of the center of

gravity may be necessary.

The configuration displayed an initially low value of directional

stability that decreased rapidly with increasing angle of attack until

directional instability occurred above an angle of 6 °. In addition,

the configuration had a positive dihedral effect that increased with

increasing angle of attack.

Langley Research Center,

National Aeronautics and Space Administration,

Langley Field, Va._ October 17, 1960.

CONFIDENTIAL

8 CONF IDENT IAL

TABLE I.- GEO_¢_TRIC CHARACTERISTICS OF THE MODEL

Wing:

Span, in .........................

Theoretical root chord, in .................

Tip chord, in ........................

Mean aerodynamic chord, in .................

Area, sq ft .........................

Aspect ratio ........................

Taper ratio .........................

Leading-edge sweep, deg ...................

Trailing-edge sweep, deg ..................

Sweep of quarter-chord line, deg ..............

Dihedral, deg ........................

Incidence, deg .......................

Thickness, percent c ...................

Elevon area, sq ft .....................

Body:

Length, in .........................

Maximum width, in ......................

Body station for maximum width_ in .............

Maximum depth (excluding canopy), in .............

Vertical tail:

Span, in ..........................

Root chord:

Theoretical, in ......................

Exposed, in .......................

Tip chord, in ........................

Leading-edge sweep, deg ...................

Trailing-edge sweep_ deg ..................Vertical-tail area (each):

Theoretical, sq ft ....................

Exposed, sq ft ......................

Rudder area (each), sq ft ..................

21.3o

19._oo.62

13.oo1.488

2.12

0.032

63.5

13 .O5

57.450

0

3

o.3s2

39.o2lO.68

36.98

1.90

4.13

7.44

6.25

1.0963.5

25

0.2_5

0.172

O.O63

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O

\\\\_i " /

m_

o

0

GJ

0

_J

.r4

0

0

_J

r_o

o

.H

o

0 %

o ul

r---I .r--i

0 o

o ._

_ r---Ir--t

©

r._0

r-I.H

!

_0.r-,I

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. - ..................

wu uge •

i0 CONF IDENTIAL

(b) Exposed wing panel.

Figure i.- Continued.

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\\\

\

00

_f

oJ

0 0

\\

O]

4

,-I o

o•r-I !

v _

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12 CONFIDENTIAL

Cm .04

0

16

12

4

a, deg

0

-12-.3 -.2 -.I 0 .I .2 .3 .4 .5 .6 ,7

CL

(a) Variation of C m and _ with C L.

Figure 2.- Effect of transition on aerodynamic characteristics in pitch.

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CONFIDENTIAL 13

2

LD

0

-2

.18 -4

-6

.14

.12

Co .10

08

.02

.I .2 .3 .4 .5 .6

CL

(b) Variation of L/D and CD with C L.

Figure 2.- Concluded.

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14 CONFIDENTIAL

Cm .04

16

12

4

a, deg

o

-.2 -.I 0 .I .2 .3 .4 .5 .6 .7

CL

(a) Variation of Cm and _ with C L.

Figure 5.- Effect of wing camber on aerodynamic characteristics

in pitch.

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- o

CONFIDENTIAL 15

6

4

2

L

D

0

2O

.18

CD .10

.02

-.I 0 .I .2 .3 .4 .5 .6

CL

(b) Variation of L/D and C D with C L.

Figure 3.- Concluded.

CON_FIDENTIAL

16 CONFIDENTIAL

.16

.08

Cm

.04

-.04

16

12

-2 -.I 0 .I 2 .3 ,4 .5 .6 .7

CL

(a) Variation of C m and _ with C L.

Figure 4.- Effect of model components on aerodynamic characteristics in

pitch.

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_ - .uc ......

w w o - -

CONFIDENTIAL 17

cD

.2o

.18

.i6

.14

.12

.IO

.OB

.061

.O4

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O-2 -.I .I

B WVBVBWB

.2

CL

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ilii

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t:i

i_i -6

i:i

iii

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LD

(b) Variation of L/D and CD

Figure 4.- Concluded.

with CL •

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18 CONFIDENTIAL

O8

Cm

.04

2O

16

12

a,deg 4

-12_-2 -,I 0 .I .2 .3 .4 .5 .6 7

CL

(a) Variation of C m and _ with C L.

Figure 5.- Effect of elevator deflection on the aerodynamic character-

istics in pitch.

CONFIDENTIAL

T.

- v ....

CONFIDENTIAL 19

2

L

D

0

CD .I 0

.08

-2 -.I 0 ,I .2 3 4 .5

CL

(b) Variation of L/D and C D with C L.

Figure 5-- Concluded.

.6 7

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2O

.O2

CONFIDENTIAL

.01

Cn 0

-.01

--.02

.01

Cl 0

-.01

Cy 0

-.I

-12 -8 -4 0 4 8 12 16

B, deg

(a) _ =-0.5 °.

Figure 6.- Effect of model components on aerodynamic characteristics

in sideslip for various angles of attack.

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CONFIDENTIAL 21

.01

Cn

0

.01

Ct

0

Cy 0

-8 -4 0

,6',deg

(b) cc = 4.8 °.

Figure 6.- Continued.

4 8 12

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22

.... - .... r _ . ....

CONFIDENTIAL

.01

Cn

0

-.01

.Of

C_

0

-.01

Cy 0

-12 -8 -4 0 4 8 12

B, deg

(c) _ : 9.3 °.

Figure 6.- Continued.

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= . _ .....

23

.01

Cn

0

-.01

.02

.0 I

C_

0

-.01

Cy 0

Figure 6-- Concluded.

4 8 12

CONFIDENTIAL

24

....... r .... . _

CONFID_T_L

Cfl

c_

Cy

.02

222

.o, !!.!

O x:

N:

-.o 3;NH::

ilii.02 _i;_

FxV'i6:

[i!i

.01 _[!:T?I

o m

_U

i:;i_ttH+

H]iH

., ii!:N

±itttt

O v-H_

t-.

-12 -8 0 8 12 16

/S', deg

Figure 7.- Effect of angle of attack on aerodynamic characteristics

in sideslip. Complete model.

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C0_ID_T_L 25

.001

0

-.001

BWV

BW

-002

-.003 0

-.003

0 -004

-.02-8 -4 0 4 8 12 16 20

,-,, deg

Figure 8.- Variation of sideslip derivatives with angle of attack.

CONFIDENTIAL

26

° . . .=

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.O1

Cy

a, deg

Figure 9.- Directional control characteristics.

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=

CONFIDENTIAL 27

Cn

C_

Cy

.01

0

-.01

.01

0

ttt

-o,

::±_

-.oztH

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:Hi

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t,t, -,÷e ................ h..

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,., ..+ .... +, .....

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re- _r]!

:2! ...... " .... * ........... +_ *-.t -++,,

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H: +,+. _i::

........... 521

:T:: ;+q_:_=,=+,g_

Hff ":_! ft!+

,-tt itt- _ft tf-i

;t_ '

q:-; U*'I

lilt _ttt t!-"

ui ::¢:ii!! -_;+_....

_tt

-_ :::1

_tt t_tt tft,

t_t f_ff ttt_ fftt

1::................kffi :!]! t_ttlt_bl _

_E :_:: i!:! :':: m',b+F +,:f4_H ::4_*,t_t_....

iTr: : i , i_

0

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::::":":: ::'::::: !!ii li_i'::::: :::: i!! ii_:

:i_i!:.::!!!!!!:_-.::" ii:i ¢_:i_.dt:::}:_: _i

....... ::I_ .............. 4

!tt11_tfl it'- tttt ]'tf t:÷:'[:i: "T:1 ltt !:1t

rtr. .iU! _ii; :i:_i_= iU:i: .... :f-_ Hq: _,_

_-4Li{f_i:i :;:::L':: i:!::;::::;r:: _ !E

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........ :::::Ji:.uu--:: _:..' #=:: .....

::::!:+_i::Hh}::r:tt::::::::::: ::::

.:m :::: :::: ................... +-..

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....... " ttt !:..... ..... ...._ t ,tr-7_...... fFii :¢::::::

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4 8 12

:*t:

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::I/r-*t

:¢rt

t+tt

::::i:::

SL::

t:::

;,2.11tttt

*4;--

tree

a, deg

Figure i0.- Roll control characteristics.

.ASA-_.,,,,g_e_ne_, v_. L-1256CONFIDENTIAL

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