by James F. Campbell FLOW FIELD SURVEY AND DECELERATOR DRAG CHARACTERISTICS IN THE WAKE OF A MODEL OF THE X-15 AIRPLANE AT MACH 2.30 AND 4.

FLOW FIELD SURVEY A N D

DECELERATOR D R A G CHARACTERISTICS

IN THE WAKE OF A MODEL

OF

THE

X-15

AIRPLANE AT MACH

2 . 3 0

A N D 4.65

by

James

F. Campbell

LangZey

Research Center

LdngZey Station, Hampton,

Va.

N A T I O N A L A E R O N A U T I C S A N D SPACE A D M I N I S T R A T I O N W A S H I N G T O N , D. C. FEBRUARY 1 9 6 6

1 i https://ntrs.nasa.gov/search.jsp?R=19660007274 2020-03-24T04:12:22+00:00Z

TECH LIBRARY KAFB, NM

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NASA 'I"U - Y Z U 3

FLOW F I E L D SURVEY AND DECELERATOR DRAG CHARACTERISTICS

IN

THE WAKE O F A MODEL O F T H E X-15 AIRPLANE

AT MACH

2.30 AND 4 . 6 5

By J a m e s F. Ca mpbel l

Langley R e s e a r c h C e n t e r

Langley Station, Hampton, Va.

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

For sale by t h e Clearinghouse for F e d e r a l Scientific and Technical Information Springfield, Virginia 22151

-

P r i c e $2.00

FLOW FIELD SURVEY AND DECELERATOR DRAG CHARACTERISTICS

IN THE WAKE O F A MODEL O F THE X-15 AIRPLANE

AT MACH 2.30 AND 4.65 By J a m e s F. Campbell Langley Research Center

SUMMARY

An investigation w a s made to determine decelerator d r a g c h a r a c t e r i s t i c s in the

asymmetric wake of a 1/12-scale model of the X-15 airplane at a Mach number of 4.65.

The four types of decelerators tested w e r e as follows: Self-inflatable (ram-air) ballute, supersonic parachute, rigid cone, and rigid tension shell. A p r e s s u r e survey was a l s o included a t Mach numbers of 2.30 and 4.65 to define the X-15 wake characteristics.

Decelerators are available that w i l l produce stable characteristics behind the X-15

airplane and with relatively high d r a g characteristics, even though the X-15 has asym­

m e t r i c wake characteristics. At trailing distances on the o r d e r of 7 to 10 t i m e s the

towing-model base diameter, the 80° rigid cone had the highest value of d r a g coefficient

of all the decelerator configurations investigated. Both the rigid tension-shell configura­

tion and the supersonic parachute configuration w e r e extremely unstable a t longitudinal distances downstream of the towing-vehicle base g r e a t e r than 4 . 5 and 6.7 base diameters, respectively; however, the tension-shell configuration indicated a potentially high d r a g capability.

INTRODUCTION

The use of towed d e c e l e r a t o r s f o r controlled reentry and/or recovery of spacecraft

and other high-speed vehicles establishes the criterion of satisfactory performance at

high altitudes and supersonic speeds. Wind-tunnel studies at supersonic and hypersonic

speeds have been made on a variety of decelerator configurations (refs. 1 to 8) and have

indicated satisfactory d r a g and stability c h a r a c t e r i s t i c s f o r s e v e r a l types of decelerators.

These investigations were undertaken with the decelerators attached to m i s s i l e or space­

craft configurations as the towing vehicle, and it is felt desirable t o determine whether

these s a m e types of decelerators are feasible f o r use on an airplane configuration. Since airplane wakes have some degree of asymmetry as compared with missile wakes and

of t h i s airplane was believed appropriate f o r these tests. An experimental study, there­

f o r e , w a s made of s e v e r a l types of d e c e l e r a t o r s attached t o a 1/12-scale model of the

X-15 airplane as the towing vehicle. In o r d e r to understand decelerator performance

m o r e completely, a p r e s s u r e survey w a s a l s o included to define the wake characteristics

behind the model. An off-center tow position f o r the d e c e l e r a t o r s w a s dictated by the.

engine arrangement on the airplane.

The four types of d e c e l e r a t o r s tested w e r e as follows: Self-inflatable (ram-air)

ballute, supersonic parachute, rigid cone, and rigid tension shell. The t e s t s w e r e per­

formed in the Langley Unitary Plan wind tunnel at a Mach number of 4.65 f o r the

decelerator-drag study and a t Mach numbers of 2.30 and 4.65 f o r the X-15 wake survey. SYMBOLS

Measurements f o r this investigation w e r e taken in the U.S. Customary System of

Units. Equivalent values are indicated herein parenthetically in the International System

(SI) in the interest of promoting use of t h i s system in future NASA reports. Details con­

cerning the u s e of SI, together with physical constants and conversion factors, are given

in reference 9. A a b C CD D d e f 2

reference area (maximum cross-sectional area of decelerator, based on maxi­

mum diameter a; includes burble fence on B1, B2, and B3 configurations)

maximum diameter of decelerator

diameter of maximum c r o s s section of self-inflatable decelerator excluding burble fence

distance f r o m apex of self-inflatable decelerator t o point of maximum c r o s s

section (excluding burble fence)

,

measured parallel t o center line

d r a g coefficient

,

D/qA

d r a g

base diameter of towing vehicle length of self-inflatable decelerator

g 2

M

P Pt q R/ft R/m r X Y Z

height in radial direction of inflation scoop on B2 and B3 self-inflatable decel­ e r a t o r configurations

local length

f r e e - s t r e a m Mach number static p r e s s u r e

total p r e s s u r e (behind a normal shock)

f r e e

-

s t r e a m dynamic p r e s s u r e

Reynolds number p e r foot Reynolds number p e r meter local radius

longitudinal distance downstream of towing-vehicle base (for wake survey, meas­ ured t o static- and total-pressure orifices; f o r decelerator-drag study, meas­ ured t o apex of decelerator)

lateral distance f r o m plane of symmetry of towing vehicle vertical distance f r o m center line of towing vehicle

APPARATUS Wind Tunnel

The t e s t s w e r e conducted in the high Mach number test section of the Langley

Unitary Plan wind tunnel, which is a variable-pressure continuous-flow tunnel. The t e s t

section is 4 feet (1.2 meters) square and '7 feet (2.1 meters) long. The nozzle leading t o

the t e s t section is of the asymmetric, sliding-block type which permits a continuous v a r i ­

ation in test-section Mach number f r o m about 2.3 to 4.7.

Models

Airplane model.- Details of the 1/12-scale model (1/12th except f o r nose geometry) of the X-15 airplane a r e shown in figure 1. Emphasis was given t o afterbody details

since t h i s is the region of the towing vehicle most likely t o affect the wake characteris­

tics, which would, in turn, affect the drag and stability of a towed decelerator. The

model was supported in the center of the tunnel by two thin s t r u t s spanning the tunnel

in the horizontal plane. In o r d e r to simulate decelerator storage, a container was

mounted on top of the fuselage r e a r w a r d of the vertical fin.

Arrangement of the wire-strain-gage balance and the low-speed gear-reduction

motor in the r e a r section of the model is shown in figure 2. The motor-driven drum w a s

remotely operated and provided variation in the steel, tow-cable length. One suitable

location f o r attachment of a tow cable on the X-15 flight vehicle is the upper engine

mount. This location r e s u l t s in an off-center tow position which was simulated on the

model by use of a pulley (fig. 2).

Decelerator models.- The following table lists the designation associated with each

decelerator along with its maximum diameter and reference a r e a :

i

-

Reference a r e a , A

-

Decelerator in. cm ft2 m2 B1 3.600 9.144 0.070686 0.006567 B2 5.875 14.923 .188253 .017489 B3 11.875 30.163 .769123 .071454 80° rigid cone 4.00 10.16 .087267 .008107 Supersonic parachute 3.50 8.89 .066814 .006207

Tension shell 4.OO 10.16 ,087267 .008107

Details of the self-inflatable (ram-air) ballute decelerator configurations (B1, B2, and B3) a r e shown in figure 3. These models were fabricated f r o m either nylon o r dacron cloth

and were coated with neoprene, which acted as a s e a l and eliminated porosity as a v a r i ­

able. There a r e four inflation scoops evenly spaced around the decelerators at the point

of maximum c r o s s section (excluding the burble fence). The nylon cords shown in fig­

u r e 3 were glued to the decelerator surface.

Three other decelerator t e s t models a r e shown in figure 4. The rigid cone and tension-shell models were made of fiber glass; the supersonic parachute model was con­

structed of wire mesh and close-woven cloth, with nylon shroud lines. (Details of a

s i m i l a r supersonic parachute configuration a r e shown in ref. 8.) Ordinates defining the

shape of the tension-shell configuration a r e presented in table I.

A swivel w a s used in attaching the decelerator models t o the tow cable t o allow

decelerator rolling motion without inducing twisting loads in the cable. A line attached t o the r e a r of all the decelerators stabilized them during starting and stopping of the 4

tunnel and also prevented the models f r o m striking the test-section windows during

periods of instability. This line w a s kept slack during data acquisition. No attempt w a s

made in this investigation to simulate decelerator m a s s o r tow-cable m a s s and elastic

properties; of course, simulating mutual dynamic characteristics between the f orebody

(X-15 model) and the decelerator was impossible under these t e s t conditions. TESTS

Test conditions f o r the flow survey behind the X-15 model a r e summarized in the following table:

Stagnation Stagnation Dynamic

Reynolds number p r e s s u r e p r e s s u r e number

I

2.30 150 339 1.56 X 106 5.12 X 106 1189

1

369.444 336 16.088 2.91 4.65

1

175

1

353 7716 56'930 352

I

16*854

Drag data were obtained on the decelerator models a t M = 4.65; the t e s t conditions

a r e as follows:

Stagnation Stagnation Dynamic _{Reynolds number}

I

temperature p r e s s u r e p r e s s u r e O F

I

OK- _Psf

I

_{w m 2} pSf

I

M / m 2 p e r f t I I 175

I

353 4262 204.066 185 8.858 1.61 X 106 1 7727 369.971 335 16.040 2.91 9.55 12274 587.682 533 25.520 4.63 15.19

Drag data at a Reynolds number p e r foot of 2.91 x l o 6 (R/m = 9.55 X 106) were obtained

on the 80° cone, the B1, and the B3 configurations a t x/d = 7.70; in addition, the B1 con­

figuration w a s tested a t a Reynolds number per foot of 4.63 X 106 (R/m = 15.19 X 106) at

x/d = 10.08.

The stagnation dewpoint was maintained below -30° F (239O K) in o r d e r to avoid

condensation effects in the test section.

MEASUREMENTS AND ACCURACY

Decelerator d r a g f o r c e w a s measured by means of an electrical strain-gage bal­

ance housed within the X-15 model and rigidly fastened to the drum and pulley support.

A p r e s s u r e rake w a s used t o perform the wake survey behind the X-15 model and is

illustrated in figure 5. The rake w a s 10 inches (25.4 cm) high and was composed of 41

total-pressure probes 1/4 inch (0.635 cm) apart and 21 static-pressure probes 1/2 inch

(1.270 cm) apart. P r e s s u r e measurements were obtained by means of p r e s s u r e t r a n s ­

ducers. In addition to f o r c e data, high-speed schlieren motion pictures w e r e taken of

each decelerator model. Schlieren photographs of the p r e s s u r e r a k e and the decelerator

models at various x/d locations behind the X-15 model are shown in f i g u r e s 6 and 7,

respectively

.

The accuracies

of

the individual quantities are estimated to be within the following

limits:

CD

. . .

k0.05

p

. . .

k 7 psf (k335 N/m2) pt

. . .

110 psf (5479 N/m2)

x,

decelerator study

. . .

*0.20 in. (k0.508 cm)

x, wake survey

. . .

10.01 in. (10.025 cm)

kO.01 in. (*0.025 cm) y

. . .

z

. . .

DISC

US

SION Wake Survey 4 . 0 1 in. (k0.025 cm)

Total-pressure distributions in the vertical plane

of

symmetry at M = 2.30 and

M = 4.65 a r e shown in figure 8 at various x/d locations behind the X-15 model base.

The data indicate that at small values of x/d (0.25 and 0.42) and within the geometric

limits of t h e model base (z = *2 inches (k5.08 cm)) the total p r e s s u r e s a r e essentially

equal t o base static p r e s s u r e

at

both Mach numbers. This no-flow condition near the

model base w a s r e f e r r e d t o as the "dead-air region'' in reference 10. A s the value of

x/d is increased, a corresponding increase is seen in total p r e s s u r e near the model

center line. At the l a r g e s t value of x/d, the p r e s s u r e recovery is about 75 percent of

f r e e - s t r e a m total p r e s s u r e f o r M = 2.30 and about 60 percent

of

f r e e - s t r e a m total

p r e s s u r e f o r M = 4.65. The l a r g e increase in pt seen

as

z is increased negatively

would be expected to occur at l a r g e r , positive z values because of X-15 geometry dif­

f e r e n c e s above and below the model center line. These data indicate the center of the

wake to be located near a positive value of z between 1 inch (2.54 cm) and 2 inches

(5.08 cm).

The vertical total- and static-pressure distributions at various distances f r o m the

model plane of symmetry (y/d = 0 t o 2.75) are shown in figure 9 f o r each x/d location.

A s lateral distance is increased f r o m y/d = 0 the asymmetric effects of the X-15 model

on total p r e s s u r e rapidly dissipate, particularly outside the region near the model base

(y/d equal t o o r g r e a t e r than 0.5). At y/d = 2.75, only a small region near z = 0

shows a variation in pt, probably as a result of the model support strut; the data pre­

sented in reference 10 f o r a cone-cylinder model using identical support s t r u t s indicated similar p r e s s u r e distributions.

The total-pressure data indicate that the location of a decelerator in the wake of

the X-15model can be critical f r o m the standpoint of decelerator drag and/or stability.

The data (fig. 8) indicate that location of a decelerator at l a r g e distances f r o m the

X-15base (at least 7.22 t i m e s the base diameter) is desirable f o r high d r a g character­

istics. Since it would be expected that the wake w i l l have the least effect on the sta­

bility characteristics of a decelerator located in the wake center, the off -center

tow-cable attachment required f o r the X-15configuration should be advantageous.

Drag and Stability

T e s t s in the Reynolds number range f r o m 1.61 X 106 to 4.63 X 106 p e r foot

(5.28 x 106 to 15.19 x 106 per m) at M = 4.65 indicated little effect of Reynolds number

on the characteristics of the 800 rigid cone, the B1, and the B3 configurations. V a r i a ­

tions of decelerator drag coefficient with trailing distance behind the X-15model base

are presented in figure 10 f o r each decelerator configuration tested at M = 4.65 f o r

R/ft = 1.61 x 106 (R/m = 5.28 X 106) only. An increase in the value of x/d r e s u l t s

in a general increase in CD f o r all the decelerator configurations investigated. Data

obtained as the trailing distance is decreased (ticked symbols) generally indicate higher

values of CD than did the data obtained at the corresponding location but with

increasing trailing distances. This trend w a s also noted in reference 7 f o r several spherical models and w a s attributed to the decelerator's passing through the transition region of the wake. The differences shown in the present investigation, however, a r e

considerably smaller than those shown in reference 7, probably because of the small

diameter of the decelerator in comparison with the model base.

Effect of decelerator s i z e on CD can be seen by comparing the r e s u l t s f o r the

B1,B2, and B3 configurations, where increasing the maximum diameter f r o m

3.600 inches (9.144 cm) f o r B1 t o 11.875 inches (30.163 cm) f o r B3 results in c o r r e ­ sponding increases in CD throughout the x/d range. This trend (illustrated graphi­ cally in fig. 11) would be expected since increased diameter exposes l a r g e r portions of the decelerator area t o the higher p r e s s u r e s that occur away f r o m the center of the

wake. It is believed that the difference in burble-fence and inflation-scoop geometries

f o r the B1 configuration as compared with those f o r the B2 and B3 configurations w i l l

not a l t e r the drag and stability r e s u l t s presented herein.

At trailing distances on the o r d e r of 7 t o 10 t i m e s the towing-model base diameter,

the 800 rigid cone h a s the highest CD value of all the decelerator configurations.

Comparison of these 80° cone data with the data presented in references 5 and 7 f o r

s i m i l a r 800 cone configurations towed behind cone-cylinder models (center-line

tow-cable attachment) shows that the cone of the present investigation has lower CD

values. It should be pointed out, however, that if comparable trailing-distance-to-base­

diameter and decelerator-diameter-to-base-diameter r a t i o s are considered (based on

a n X-15 model effective base diameter l a r g e r than 4 inches (10.16 cm), as indicated by

the p r e s s u r e results), comparable d r a g values might be attained. Comparison of the stability c h a r a c t e r i s t i c s of these cone configurations by m e a n s of visual observation showed little difference in stability t r e n d s with x/d, particularly in the region of maxi­

mum CD where the 80° cone configurations w e r e stable r e g a r d l e s s of the towing vehi­

cle (X-15 model of the present investigation and cone-cylinder models of ref. 7). The

r a m - a i r decelerator configurations (B1, B2, and B3) a l s o showed a high degree of sta­

bility at l a r g e x/d values.

Although the tension-shell configuration indicates a potentially high drag capability,

data w e r e not obtained at x/d locations f a r t h e r behind the forebody than are shown in

figure 10 (that is, at x/d values g r e a t e r than 4.5) because of s e v e r e oscillations of the

model. Subsequent t e s t s (unpublished data) have shown t h i s tension-shell configuration

t o have s i m i l a r instability c h a r a c t e r i s t i c s when tethered behind a cone-cylinder model

with a center-line tow cable. Similar oscillations w e r e a l s o noted f o r the supersonic

parachute configuration, and resulted in termination of drag-data acquisition near x/d

of 6.7.

CONCLUSIONS

A wind-tunnel investigation of the flow field and decelerator d r a g characteristics

in the asymmetric wake of a 1/12-scale model of the X-15 airplane indicated the fol­

lowing conclusions :

1. Decelerators are available that will produce stable characteristics behind the

X-15 airplane and with relatively high d r a g characteristics, even though the X-15 has

asymmetric wake characteristics.

2. At trailing distances on the o r d e r of 7 to 10 t i m e s the towing-model base diam­

eter, an 80° rigid cone had the highest value of d r a g coefficient of all the decelerator conf igurations investigated.

3. Both a rigid tension-shell configuration and a supersonic parachute configura­

tion were extremely unstable at longitudinal distances downstream of the towing-vehicle

base g r e a t e r than 4.5 and 6.7 base diameters, respectively; however, the tension-shell

configuration indicated a potentially high drag capability.

Langley Research Center,

National Aeronautics and Space Administration,

Langley Station, Hampton, Va., December 1, 1965.

9

REFERENCES

1. Nebiker, F. R.: Feasibility Study of an Inflatable Type Stabilization and Deceleration

System f o r High Altitude and High-Speed Recovery. WADD Tech. Rept. 60-182,

U.S. Air Force, Dec. 1961.

2. Aebischer, A. C.: Investigation To Determine the Feasibility of Using Inflatable

Balloon Type Drag Devices f o r Recovery Applications in the Transonic, Supersonic,

and Hypersonic Flight Regime

-

Part I. Functional and Performance Demonstra­

tion. ASD-TDR-62-702,

Pt.

1, U.S. Air Force, Oct. 1962.

3. Alexander, W. C.: Investigation To Determine the Feasibility of Using Inflatable

Balloon Type Drag Devices for Recovery Applications in the Transonic, Supersonic,

and Hypersonic Flight Regime

-

Part II. Mach 4 t o Mach 10 Feasibility Investiga­

tion. ASD-TDR-62-702, Pt. 11, U.S. Air Force, Dec. 1962.

4. Coats, J a c k D.: Static and Dynamic Testing of Conical Trailing Decelerators for the

Pershing Re-Entry Vehicle. AEDC-TN-60-188, U.S. A i r Force, Oct. 1960.

5. Charczenko, Nickolai; and McShera, John T.: Aerodynamic Characteristics of Towed

Cones Used

as

Decelerators at Mach Numbers F r o m 1.57 t o 4.65. NASA T N D-994,

1961.

6. McShera, John T., Jr.: Aerodynamic Drag and Stability Characteristics of Towed

Inflatable Decelerators at Supersonic Speeds. NASA TN D-1601, 1963.

7. Charczenko, Nickolai: Aerodynamic Characteristics of Towed Spheres, Conical

Rings, and Cones Used as Decelerators

at

Mach Numbers F r o m 1.57 t o 4.65. NASA

TN D-1789, 1963.

8. Charczenko, Nickolai: Wind-Tunnel Investigation of Drag and Stability of Parachutes

at Supersonic Speeds. NASA TM X-991, 1964.

9. Mechtly, E. A.: The International System d Units

-

Physical Constants and Con­

version Factors. NASA SP-7012, 1964.

10. McShera, John T., Jr.: Wind-Tunnel P r e s s u r e Measurements in the Wake of a

Cone-Cylinder Model

at

Mach Numbers of 2.30 and 4.65. NASA TN D-2928, 1965.

TABLE I

ORDINATES DEFINING TENSION-SHELL MODEL

~~ r in. cm in. cm 0.000 0.000 0

.oo

0.000 .210 .533 .10 .254 .422 1.072 .20 .508 ,630 1.600 .30 .762 .832 2.113 .40 1.016 1.026 2.606 .50 1.270 1.218 3.094 .60 1.524 1.396 3.546 .70 1.778 1.562 3.967 .80 2.032 1.720 4.369 .90 2.286 1.864 4.735 1

.oo

2.540 1.996 5.070 1.10 2.794 2.116 5.375 1.20 3.048 2.216 5.629 1.30 3.302 2.308 5.862 1.40 3.556 2.384 6.055 1.50 3.810 2.448 6.218 1.60 4.064 2.496 6.340 1.70 4.318 2.530 6.426 1.80 4.572 2.554 6.487 1.90 4.826 2.562 6.507 2.00 5.080 11

.

1 4 . 5 0 2 . 1 0 ( 5 . 3 3 4 ) S t P 0.000 (0.000) c_10.21­ ( 2 5 . 9 3 3 )

1 _I I I I I I I I I Side v i e w P l a n e 0 1 s y m m e t r y

7

Figure 1.- Concluded.

1/16 -in

.

r

t o w c a b l e (0.16) c a b l e 16) S i d e v i e w

1 6 c o r d s s p a c s d 2 2 . 5 ' a p a r t e= 3.20 4

-(8.128) -0.254 0.306 L B u r b l e f e n c e ( 0 . 6 4 5 ) _{( 0 . 7 7 7 )} I I n f l a t i o n s c o p e ( f o u r e v e n l y s p a c s d ) (a) 81 configuration.

E c o r d s s p a c e d 45' a p a r t c ( f o u r e v e n l y s p a c e d ) B u r b l e f e n c e g u Maximum s e c t i o n

-!I

C o n f i g u r a t i o n 110 S e c t i o n A - A (b) B2 and B3 configurations. Figure 3.- Concluded.

( 6 . 0 5 )2 . 3 8 4 C l o s e - w o v e n c l o t h

1

S h r o u d l i n e s 1 . 0 0

I _

4

( 2 . 5 4 ) 9.00 __ _I ( 2 2 . 8 6 ) N o t e : O r d i n a t e s o f t e n s i o n -s h e l l m o d e l a r e -s h o w n i n t a b l e I 8 0 ° c o n e a - 3 . 5 0 ( 8 . 8 9 ) L W i r e m e s h S u p e r s o n i c p a r a c h u t e -T e n s i o n s h e l l

Figure 4.- Decelerator details. (Dimensions are given first i n inches and parenthetically i n centimeters.)

. .

T o t a l p r e s s u r e

.

7-

O r i f i c e

. .

. .

S t a t i c p r e s s u r e o r i f i c e

. .

. .

. .

10.00 (25.40)

. .

. .

. .

. .

.

:A

.

:T

1

0.50 -0.25

1

:

:

&0.50 (1.27) _{S i d e v i e w} F r o n t v i e w S t a t ic - p r e s s u r e o r i f i c e \ _____2_ T o t a l - p r e s s u r e o r i f i c e Top v i e w

Figure 5.- Details of pressure rake. (Dimensions are given f i r s t in inches and parenthetically in centimeters.)

x / d = 7 . 2 2 x / d = 2 . 5 2

x / d = 0.81 x / d = 0 . 4 2

x / d = 0 . 2 5

(a) M = 2.30. L-65-9031 Figure 6.- Schlieren photographs of pressure rake at various x/d locations behind the X-15 model.

19

I , .. .. , , , .. . ~ . ..-*­ x / d = 1 . 2 2 x / d = 5 . 0 5 x/d = 2 . 5 2 x / d 3 0 . 4 2 ! x / d = 0 . 2 5 (b) M = 4.65. L-65-9032 Figure 6.- Concluded.

x/d 7.63 _{x/d 5.05}

x/d

=

2.55 x/d 1.53

(a) B 1 self-inflatable configuration. L-65-9025 Figure 7.- Schlieren photographs of decelerator models at various x/d locations behind the X-15 model. M = 4.65.

2 1

x/d

=

7.75

x/d 5.18

x/d 4.25 x/d

=

2.63

(b) Bp self-inflatable configuration. L-65-9026 Figure 7.- Continued.

-

-

,

-...

-,..

...

,.., ,,,.,,...

....

.-.

, , ,,., , ,

.

,,, ,, I,

.

, .,

.

,,

...

,

..

,

.

.,..

,,.,

.

.,

.

.

.

,,. ,

.

,

.

, ,

. ---.---..

-.. .

.,..,.,

.

,.,,.

.

,.,

... .

.I. x/d

=

7.70 x/d

=

4.28 x/d

=

2.63

x/d

=

1.00

(c) Bg self-inflatable configuration. L-65-9027 Figure 7.- Continued. 23 4

x/d

=

7.88 x/d

=

5.30

x/d

=

2.88 x/d

=

1.85

(d) BOo rigid cone. L-65-9028

Figure 7.- Continued.

t

x/d

=

6.65 x/d

=

2.85

x/d 1.03

(e) Supersonic parachute. L-65-9029

I

Figure 7.- Continued.

c

x/d

=

7.60 x/d

=

6.33 X/d

=

4.35 _x/d 3.35 X/d

=

1.53 (f) Tension shell. L-65-9030 Figure 7.- Concluded. 26

z , cm z , cm -20 -15 -10 - 5 0 5 1 0 -20 -15 -10 -5 0 5 10- 4 5 I I I I I I I -40 -3 5 -30 -25 P t , kN/m2 - 20 - 15 - 10 z , in. z, in.

2 . cm -20 -15 -10 -5 I US -6 -4 -2 2 , i n . Figure 9.­ z , cm -10 5 10 3

-

-15 I 45 40 35 Y/d 0 0 0 0.25 A 0.50 30 0 0.75 n 1.00 n 1.25 0 2.75 25 p t . kN/m2 20 15 10 5 0 6 4 p . kN/mZ I4.65' 2 0 -4 -2 0 2 b 2 , i n . (a) x/d = 0.25.

Vertical total- and static-pressure distribution at various y/d locations.

z. cm -20 -15 -10 I -15 -5 0 5 10 I I 1000 L5 900 LO 800 I I 15 700 Y/d 0 0.25 0.50 IO 600 0.75 h 1.00 P t l P S f 0 1.25 0 2.75 !5 500 1 p t . kN/m2 I I !O 400

i

15 300 200

i

_I LO I I 100 I 5 0 0 ~ !

i

I 4 80 P 9 P S f I p , kN/m2 6 120 I 2 40 1 I2.30 1 ₁ I 0 0. -4 -2 z. i n . (b) x/d = 0.42. Figure 9.- Continued. 29

Z . cm z, cm -20 -15 -10 -5 0 5 1 0 -20 -15 -10 - 5 '-8 -6 -4 -2 0 2 4 -8 -6 z, in. z , in. (c) x/d = 0.81. Figure 9.- Continued. I 5 10 45 40 35 30 25 Pt,kN/mZ 20 15 LO 5

I

0 6 4 P , kN/m2 2 0 J 30

I , cm _{Z . cm}

z , in. z. in.

(d) x/d = 2.52. Figure 9.- Continued.

z. cm -20 -15 -10 5 I l,O -20 -15 -10 I -5 I 0 I 5 10 ₁

P

c n 0.; A 0.: 0 0.i o 1.c

P

n I.; d 0 2.7

f

l ?

P

I

4

I

- 6 - 4 p , kN/m2 M = 4 ,

t

1 - 2 !I t* 4 _{-2 0} 0 z, in. z , in. (e) x/d = 5.05. Figure 9.- Continued. 32

Z. cm z, cm -20 -15 -10 3 5 - 10 -20 -15 0 -5 0 5 10 1000

‘

I I I _, , , I I I 1 I ~ I _I 400 300 200 100 0 120 P . P S f 80 <N/In2 M = 2.30 40

I l l

0 -2 0 2 4 z. in. z , In. (f) x/d = 7.22. Figure 9.- Concluded. 33

.4 CD .2 0 " 0 1 2 3 4 5 6 7 8 9 10 x/d

Figure 10.- Variation of drag coefficient with x/d for t h e decelerator configurations. M = 4.65. (Ticked symbols indicate data taken as x/d i s decreased.)

34

.

D r a g a r e a ,

CDA, f t 2

D e c e l e r a t o r d i a m e t e r / F o r e b o d y d i a m e t e r , a/d

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