FINAL SUMMARY REPORT GER-12842, VOLUME I

b

' I 1 . I I I study 01 EXPANDABLE

TERMINAL DECELERATORS FOR B MARS ATMOSPHERE ENTRY 1

GOODY EAR AEROSPACE CORPORATION AKRON, OHIO

704

JET PROPULSION LABORATORY JPL CONTRACT NO. 951153

3 October 1 9 h Copy No. A %

https://ntrs.nasa.gov/search.jsp?R=19670002392 2020-07-28T16:00:48+00:00Z

GOODYEAR AEROSPACE COR PO R AT IO N

A K R O N IS . OHIO

STUDY O F EXPANDABLE, TERMINAL

DECELERATORS FOR MARS ATMOSPHERE ENTRY,

Volume I - Fina l S u m m a r y Repor t

GER-12842, Rev A 2 1 October 1966

Jay L. Musi l

Goody e a r A e r o s pa c e C o r po rat ion, Akron, Ohio

fo r

Jet Propuls ion Laboratory, California Insti tute of Technology

Pasadena, Calif.

T h b d w u paformed far the Jet pmpllsian Imboratorg, California Institute of Technology, sponsored by the

tion urxiut National Aeronautics and Space Contract NAS7-100.

. .

GER- 12842, VOL I I I I I 1 I I I II I 1 1 I e E 1 1 I

FOREWORD

The r e s e a r c h descr ibed in this f inal s u m m a r y r epor t (Vol-

u m e I) was pe r fo rmed by Goodyear Aerospace Corporat ion,

subs id ia ry of The Goodyear T i r e & Rubber Company, Akron,

Ohio, for the J e t Propulsion Labora to ry , Cal i fornia Inst i -

tute of Technology, under the au thor i ty of Contract No.

951153.

October 1966. M r . J ames M. Brayshaw, J r . , was the

J e t Propuls ion Labora tory Technical Representat ive.

The work was conducted f r o m December 1965 to

The work was performed unde r the gene ra l d i rec t ion of

M r . R. L. Ravenscraf t , manage r of the Aero-Mechanica l

Engineer ing Division and M r . F r e d R. Nebiker , manage r

of the Recovery Systems Engineer ing Department .

p r o g r a m was d i rec ted by M r . Jay L. Musi l , p ro jec t engi-

n e e r .

The

Pe r sonne l contributing to this effor t w e r e M s s r s . A. P. Ahar t ,

configuration, weight, and s t r eng th ana lyses ; K. Birklein

and J. W. Sch lemmer , computer ana lyses ; I. M. Ja remenko ,

p r e s s u r e dis t r ibut ion analyses; and W. W. Sowa, t h e r m a l

ana lyses .

This is Volume I of two volumes.

supporting t e c hnical information.

Volume I1 presen t s the

GER.12842. VOL I

TABLE O F CONTENTS

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . .

LIST O F ILLUSTRATIONS . . . . . . . . . . . . . . . . . . LIST O F TABLES . . . . . . . . . . . . . . . . . . . . . . . Section Ti t le

I DESCRIPTION OF PROGRAM . . . . . . . . . . . 1 . Introduction . . . . . . . . . . . . . . . . . 2 . P r e s e n t Analysis P rocedure for Aerodynamic De-

3 . Analysis Procedure Establ ished f o r P r o g r a m . . ce le ra to r Applications . . . . . . . . . . . . .

I1

111

IV

V

ENVIRONMENTAL CONSIDERATIONS . . . . . . . 1 . Atmospheres and Tra j ec to r i e s . . . . . . . . . 2 . Decelera tor Configurations . . . . . . . . . . ANALYTICAL CONSIDERATIONS . . . . . . . . . . 1 . Basis of Analysis . . . . . . . . . . . . . . . 2 . Decelera tor Weight Relationships . . . . . . .

RESULTS O F ANALYSIS . . . . . . . . . . . . . . 1 . Tra jec to r i e s Considered . . . . . . . . . . .

3 . Decelera tor Weight . . . . . . . . . . . . . .

5 . Effect of Target Mach Number Variat ion . . . .

2 . Decelera tor Size . . . . . . . . . . . . . . .

4 . T e m p e r a t u r e and Mater ia l Considerat ions . . . .

SYSTEM COMPARISONS . . . . . . . . . . . . . 1 . B a s i s fo r Comparison and Selection . . . . . . . 2 . Dynamic Analysis . . . . . . . . . . . . . . .

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9 15

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2 1

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47

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49

. V-

Section Ti t le Page

3 . Comparisons of Composite Sys tems. . . . . . . a. G e n e r a l . . . . . . . . . . . . . . . . . b. I tems 1 and 2 - Decelera tor Diameter and Al-

titude a t Mach Number 1. . . . . . . . . . - c. I tems 3 and 4 - Decelerator Weight and En-

velope Weight . . . . . . . . . . . . . . - d. I tems 5 and 6 - Design and Actual Maximum

Decelera tor Envelope T e m p e r a t u r e . . . . . - e . I tem 7 - Auxiliary Gas Inflation Sys tem Weight - f . I tems 8 , 9 and 10 - Ancil lary Equipment

Weight, Attachment Design Saiety F a c t o r , and Packaging Volume . . . . . . . . . . . .

g. I tem 11 - Composite Sys tem Velocity a t 5 , 0 0 0 f t above T e r r a i n . . . . . . . . . .

- h. I tem 12 - Composite System Fl ight-Path Angle a t 5 ,000 ft above T e r r a i n . . . . . .

- i . I tems 13 and 14 - System Oscillation Ampli- tude and Rate. . . . . . . . . . . . . . .

i I tem 15 - Maximum Operating g-Level . . . - k. I tems 16 and 17 - Total Dece lera tor Sys tem

Weight and Weight F rac t ion . . . . . . . .

- -

61 61

61

6 3

64 64

65

66

66

67 67

68

VI RECOMMENDATIONS. . . . . . . . . . . . . . 69

VI1 CONCLUSIONS . . . . . . . . . . . . . . . . . . 73

LIST O F REFERENCES. . . . . . . . . . e . . . 7 5

Appendix

A DECELERATOR CHARACTERISTICS . . . . . . 77

B REFINED POINT- lMASS TRAJECTORY COMPUTA- TIONS AND TRANSIENT HEATING CALCULATIONS . 103

C DYNAMIC STABILITYANALYSES 117 . . . . . . . . .

I I I I I 1 1 I I 1 8 1 1 I I I 1 3

TABLE O F CONTENTS GER-l2842A, VOL I

-vi-

-

Revised 2 1 October 1966

GER-12842, VOL I

LIST O F ILLUSTRATIONS

F igure

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Ti t le ~~ ~~ ~~~

Interrelat ionships of Dece lera tor Applications . . . Functional Flow Diagram of Constraining Fac to r s and Va ria ble Pa ram et e r s . . . . . . . . . . . . . . .

Tra jec to r i e s for Mars Atmosphere Ent ry (VM7 Atmos- p h e r e ) . . . . . . . . . . . . . . . . . . . . . . Tra jec to r i e s fo r Mars Atmosphere En t ry (VM8 Atmos- p h e r e ) . . . . . . . . . . . . . . , . . . . . . .

J P L M a r s En t ry Capsule . . . . . , . . . . . . . Tra jec to r i e s f o r Mars Atmosphere En t ry (Atmospheres VM3 and VM4) . . . . . . . . . . . . . . . . . . De c e le ra to r Concepts . . . . . . . , . . . . . . . Drag Coefficient Variation with Mach Number . . . . Decelera tor Weight . . . . . . . . . . . . . . . .

Six Steps f o r Determing Decelera tor Size (All Values a r e Typical) . . . . . . . . . . . . . . . . . . .

Decelera tor Size Requirements (Tra j ec to r i e s A1 and A4; Atmospheres VM7 and VM8) . . . . . . . . . .

Decelera tor Size Requirements (Tra j ec to ry 1 9 and Atmosphere VM8) . . . . . . . . . . . . . . . . Decelera tor - to- Total Weight (Tra j ec to r i e s A1 and A4; Atmospheres VM7 and VM8) . . . . . . . . . . . .

Decelera tor - to- Total Weight (Tra j ec to ry 19 and Atmos- phere VM8) . . . . . . . . . . . . . . . . . . .

Aerodynamic and Thermal Effects on Decelera tor En- velope (Tra jec tor ies 1 9 and A l ) . . . . . . . . .

Page

3

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12

13

14

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18

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25

28

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- vii -

8 LIST O F ILLUSTRATIONS GER-12842, VOL I

Figure

16

17

18

19

20

2 1

2 2

23

24

25

26

27

28

2 9

B- 1

B-2

B-3

B-4

- viii-

T i t le

Minimum Decelerator Envelope Unit Weight ( T r a j e c - tory A l , hT = 20,000 f t , Dacron) . . . . . . . . .

Minimum Decelerator Envelope Unit Weight ( T r a j e c - tory A l ,

Minimum Decelerator Envelope Unit Weight (Tra j ec - tory 19, hT = 20,000 f t , Dacron) . . . . . . . . . Minimum Decelerator Envelope Unit Weight ( T r a j e c - tory 19, hT = 30,000 f t , Dacron) . . . . . . . . .

Change i n Pe rcen t Total Drag A r e a (Tra j ec to ry 19 and Atmosphere VM8) . . . . . . . . , . . . . . . . Change in Altitude with Variation of Ta rge t Mach Num- be r f r o m 1. 0 (Tra jec tory 19 and Atmosphere VM8).

Variation of Decelerator Weight with Ta rge t Mach Number (Tra jec tory 19; Attached BALLUTE) . . . . Trailing BALLUTE . . . . . . . . , . . . . . . . Attached BALLUTE. . . . , . . . . . . . . . . . Tucked-Back BALLUTE . . . . . . . . . . . . . A I R M A T C o n e . . . . . . . . * . . . . . . . . .

Decelerator Oscillation Charac t e r i s t i cs (Atmosphere VM8; Tra jec tory 19) . . . . . . . . . . . . . . .

Decelerator Oscil lation Charac t e r i s t i c s (Atmosphere VM8; Tra jec tory 2 2 ) . . . . . . . . . . . . . . .

Rocket Boost Technique f o r Simulation T e s t . . . . .

Space/Time and Envelope Trans i en t T e m p e r a t u r e v e r - sus Mach Number (Tra j ec to ry A l ) . . . . . , , , ,

Space/Time and Envelope Trans i en t T e m p e r a t u r e v e r - sus Mach Number (Tra j ec to ry B3) . . . . . . , ,

Space/Time and Envelope Trans i en t Tempera tu re v e r - sus Mach Number (Tra j ec to ry 19) . . . . . . - a

Space/Time and Envelope Trans i en t T e m p e r a t u r e v e r - sus Mach Number (Tra j ec to ry 22) . . . . . . . - I

= 20,000 f t , Nomex) . . . , . . . . . hT

.

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8 1 - I 1 1 I I 1

I I I I I s 8 0 E 1

m

LIST O F ILLUSTRATIONS GER-l2842A, VOL I

F igu re

B-5

B-6

c- 1

c-2

c - 3

c - 4

c - 5

C-6

Ti t le

Space/Time and Envelope Trans ien t Tempera tu re v e r - sus Mach Number (Tra j ec to ry 23)

Space/Time and Envelope Trans ien t Tempera tu re v e r - sus Mach Number (Tra j ec to ry 30)

. . . . . . . . .

. . . . . . . . .

Decelera tor Oscillation Charac t e r i s t i c s for Trai l ing BALLUTE (Atmosphere VM7; Tra j ec to ry 22; p = 0. 0 rad /sec) . . . . . . . . . . . . . . . . . . . . . Decelera tor Oscillation Charac t e r i s t i c s for Trai l ing BALLUTE (Atmosphere VM7; Tra j ec to ry 22; p = 0. 5 rad /sec) . . . . . . . . . . . . . . . . . . . . . Decelera tor Oscillation Charac t e r i s t i c s for Trai l ing BALLUTE (Atmosphere VM7; Tra j ec to ry 22; p = 0. 75 rad /sec) . . . . . . . . . . . . . . . . . . . . . Decelera tor Oscillation Charac t e r i s t i c s f o r Trai l ing BALLUTE (Atmosphere VM7; T r a j e c t o r y 22; p = 1. 0 rad /sec) . . . . . . . . . . . . . . . . . . . . . De c e le ra to r Os cilla tion C ha r a c te ri s ti c s fo r Trai l ing BALLUTE (Atmosphere VM8; Tra j ec to ry 19; p = 0 . 5 r a d / s e c ) . . . . . . . . . . . . . . . . . . . . . Decelera tor Oscillation Charac t e r i s t i c s for Trai l ing BALLUTE (Atmosphere VM8; Tra j ec to ry 19; p = 1 . 0 rad /sec) . . . . . . . . . . . . . . . . . . . . .

Revised 2 1 October 1966

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GER- 12842. VOL I

LIST O F TABLES

Table

I

I1

I11

IV

A- I

A- I1

A- 111

A- IV

A-V

A- VI

A- VI1

A- VI11

A- IX

A-X

A-XI

c-I

Ti t le

Charac te r i s t ics of VMAtmospheres . . . . . Init ial En t ry Conditions . . . . . . . . . . . Cases Selected fo r Extended Consideration . . Comparison of Decelerator Sys tems . . . Comparison of Decelerator Charac te r i s t ics . .

Comparison of Decelerator Charac t e r i s t i cs . .

Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac te r i s t ics . .

Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac te r i s t ics . . Comparison of Decelerator Charac t e r i s t i c s . . Comparison of Decelerator Charac te r i s t ics . .

Manhours and Cost . . . . . . . . . . . . .

. .

. .

. .

. .

. .

. .

. .

. .

. .

. .

. .

. .

. .

. .

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Page

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62

8 1

83

8 5

8 7

8 9

91

93

95

97

99

101

117

-xi-

GER- 12842, VOL I

SECTION I - DESCRIPTION OF PROGRAM

1. INTRODUCTION

Goodyear Aerospace Corporation (GAC) has conducted a pa rame t r i c study

to de te rmine the suitabil i ty of expandable t e rmina l dece le ra to r s for a

M a r s lander capsule .

J e t Propuls ion Labora to ry (JPL), the study was based on the analytical

formulation of the effects associated with the model environments of

M a r s and specified en t ry capsule cha rac t e r i s t i c s and en t ry conditions.

These effects, charac te r i s t ics , and conditions governed the requi re -

ments for the engineering applications of expandable dece lera tor devices .

Under the t e r m s of Contract No. 951153 f r o m the

The ma in objective was to determine fundamental engineering s y s t e m

design requirements for initial- s tage, expandable dece lera tors that

provide stabil ization and retardation for M a r s lander capsules (the en-

t i r e s y s t e m including the entry vehicle and dece le ra to r is r e f e r r e d to

a s the en t ry capsule) .

is t i c ' s w e r e analyzed:

To fulfill this objective the following cha rac t e r -

1.

2.

3 .

4.

5.

6.

7.

8.

9 .

Structural integrity

Per formance effectiveness

Aerodynamic stabil i ty

Bulk and weight

Heat insulation

Mat e ria Is

Ancillary equipment

Deployment and inflation

P a c kag ing

- 1 -

SECTION I - DESCRIPTION O F PROGRAM GER-12842, VOL I

The final objective was to compare and recommend:

1. Des i rab le configurations

2 . A r e a s of additional study and analysis

3 . Simulation and t e s t r equ i r emen t s

The charac te r i s t ics of var ious expandable dece le ra to r s w e r e de te rmined

by the formulation of uncomplicated s t ra ight forward engineering ana lys i s

and design. Then, des i r ab le dece le ra to r s that r e t a r d capsules to about

Mach 1 n e a r heights of 10, 000 , 20, 000 , and 30 , 000 f t above the Mar t ian

t e r r a i n w e r e se lec ted fo r more-de ta i led ana lyses and invest igat ions.

F igure 1 gives the in te r re la t ionship of aerodynamic dece le ra to r appl i -

cations f o r M a r s a tmosphe re en t ry . The r equ i r emen t s and technology

breakdowns assoc ia ted with operat ional functions, s y s t e m design, bas ic

sc ience , and applied engineering a r e re la ted d i r ec t ly to those requi red

under the scope of this p rog ram.

2. PRESENT ANALYSIS PROCEDURE FOR AERODYNAMIC DECELERA- TOR APPLICATIONS

To date aerodynamic dece le ra to r design h a s depended p r i m a r i l y on the

available technology developed f r o m spec ia l ized previous applications

and investigations. The accepted procedure fo r es tabl ishing a design

for a new application is given below.

1 . Survey pe r fo rmance data re la t ing to var ious de-

c e le r a t o r configurations

2 . Evaluate these data to de t e rmine the extent that

a par t i cu la r configuration and operat ing condi-

tions r e l a t e to the specified r equ i r emen t s for the

new application

3 . Conduct a p re l imina ry des ign effor t and build t e s t

models

2

SECTION I - DESCRIPTION OF PROGRAM GER- 12842A, VOL I

O B J E C T I V E S

A

- REQUIREMENTS T E C H N O L O G Y

MISS ION

A TMOS P H E R I C E N V I R O N M E N T

T E R R A I N

G E O L O G Y

A P P L I E D ENGINEERING

E V A L U A T I O N B Y S I M U L A T I O N O F PHENOMENA A F F E C T I N G DESIGN

E X P E R I M E N T A L T E S T OF SENSING,

A C T U A T I O N AND D E P L O Y M E N T METHODS

S T A T I C A N D DYNAMIC PERFORMANCE -S IMU L A T l ON

1 0 P E R A T I ONA L F UNCTl ONS

E N T R Y T R A J E C T O R Y C O N T R O L F O R A L T I T U D E AND MACH NUMBER I NTERCE P T S

SIGN1 F I C A N C E

ENGINEERING D E V E L O P M E N T

N A T I O N A L P R E S T I G E

BASIC SCIENCE I

A N A L Y T I C A L F O R M U L A T I O N O F E N V I R O N M E N T A L FACTORS A N D E F F E C T S G O V E R N I NG ENG I N E E R I NC A P P L I C A T I O N S

F O R M U L A T I O N OF E N G I N E E R I NG TECHNIQUES O F ANALYSIS AND I DESIGN

SYSTEM DESIGN

S T R U C T U R A L I N T E G R I T Y

P E R FORMA NCE E F F EC T I V E NESS

S T A T I C AND DYNAMIC S T A B I L I T Y

B U L K AND WEIGHT

H E A T INSULATION

D E P L O Y M E N T AND I N F L A T I O N R A T E S

M A T E R I A L S

SENSING, SEQUENCING, A C T U A T I O N

SYSTEM AND COMPONENT R E L I A B I L I T Y

Figure 1 - Interrelationships of Decelerator Applications

Revised 21 October 1966 - 3 -

SECTION I - DESCRIPTION O F PROGRAM GER-12842, VOL I

4. Conduct wind- tunnel, functional, and environmental

t e s t s to es tabl ish the validity of the predicted

performance of a specific design f o r the new appli-

cation and operating environments

5. Design, build, and conduct fu l l - sca le , free-fl ight

t e s t s of the dece lera tor s y s t e m under simulated

opera ti ona 1 conditions and environments

This procedure has been demonstrated successfully. However, i t has

been c a r r i e d out too often with the expense of unscheduled, additional

t ime and cost f o r redesign and r e t e s t

countered was the extrapolation of sys t em design data f r o m previous

applications. In many cases and usually a f t e r the p rogram was well

underway, unforseen f ac to r s o r changes made the avialable data in-

adequate o r not applicable. As a r e su l t , in terat ion of Steps 3 , 4 , and

5 was required. Additionally, procedures and t ime s c a l e s es tabl ish-

ing requirements f o r aerodynamic dece lera tor applications w e r e often

incompatible with the development of the m o s t reliable and efficient de-

ce le ra tor sys tem design.

One of the m a j o r difficulties en-

3 . ANALYSIS PROCEDURE ESTABLISHED FOR PROGRAM

This program,whi c h comprised a p a r a m e t e r study, took a different ap-

proach to evaluating the charac te r i s t ics of aerodynamic dece le ra to r s

a s compared with the analysis procedure outlined above. To i l l u s t r a t e

this approach, F igure 2 shows a functional flow d iag ram of the f ac to r s

and var iable pa rame te r s appropr ia te to the application of aerodynamic

dece lera tors for the t ra jec tory control of planetary e n t r y vehicles . The

inputs and outputs a r e assoc ia ted with the envi ronments , cons t r a in t s ,

requi rements , and objectives of this study.

The simplicity of the functional d i ag ram is somewhat decept ive.

s e r v o c i rcu i t is used as a n analogy, the s y s t e m is "open-loop, 'I which

a t once points up the inherent difficulty of aerodynamic dece le ra to r

If a

- 4-

SECTION I - DESCRIPTION O F PROGRAM GER-l2842A, VOL I

ATMOSPHERES:

E NV I RON ME NT AL * c o ND I - NOTE:

T IONS A T DEPLOYMENT: SOLID L I N E S R E P R E S E N T I N V A R I A N T F A C T O R S F O R

P H Y S I C A L CONSTRAINTS: T I I 1 WEIGHT, VOLUME, AND

I q , g'S, 6, E T C . TRAJECTORIES:

I I

I I .a L _. a

A N Y ONE P A R T I C U L A R T R A J E C T O R Y A N A L Y Z E D WITH E X C E P T I O N OF THOSE WITH ASTERIKS.

DASH E D L I N E S R E P R E S E N T V A R I A B L E S , P A R A M E T E R S. OR E F F E C T S T O BE E V A L U A T E D IN THIS STUDY.

COMPOSITE SYSTEM CHARACTERISTICS

CHARACTERISTICS

TARGET* I VM7, VMB

I N I T I A L E N T R Y

C O N D l T IONS:

ve AND Y e

1

ii V O L U M E A V A I L A B L E

AERODYNAMIC S T A B I L I T Y

j i I I

I POINTS

M, h , OMAX, e' M A X

1 _1 I----- r---- I I

WEIGHT I I

-I

I M A T E R I A L S A N D

I

I

U D E P L O Y M E N T , I I N F L A T I O N , A N D A T T AC HME N T

I I

WEIGHT I AND B U L K

----I A SSO C I A T E D E Q U I P M E N T

Figure 2 - Functional Flow Diag ram of Constraining Fac tors and Variable P a r a m e t e r s

Revised 21 October 1966 - 5 -

SECTION I - DESCRIPTION O F PROGRAM GER-12842, VOL I

design technology. "Matching"(that i s , achieving a n optimized design)

the pa rame te r s and f ac to r s for a des i rab le s y s t e m mus t be accom-

plished by techniques similar to the graphic solutions f o r s o m e types of

mathematical equations involving transcendental functions.

In rea l i ty there i s feedback through the dynamic c h a r a c t e r i s t i c s of the

physical system as a r e su l t of coupling through the external operating

environment and the result ing s y s t e m motions.

back is nonlinear by the v e r y na ture of the per formance charac te r i s t ics

of aerodynamic dece lera tor devices when moving through an a tmosphere

a t high speeds, necessitating adaptation of the p a r a m e t e r s to the des i re?

s y s t e m performance.

Unfortunately this feed-

The purpose of this discussion is not to emphasize the difficulty of this

study, but ra ther to demonst ra te the validity of the engineering analy-

sis approach and procedures established F u r t h e r , this analysis

approach was appropriate s ince i t permit ted evaluation fo r all possible

aerodynamic dece lera tor s y s t e m concepts.

A s shown by Figure 2, the significant f ac to r s and p a r a m e t e r s that r e -

quired consideration and evaluation to es tab l i sh the design of deployable

aerodynamic dece lera tor s y s t e m s f o r the M a r s lander capsule included:

1 . Initial e n t r y conditions (V ye , CY,, p , g , r , etc. ) e ' as s ocia ted with the designated JPL t ra j e c to r i e s

( A l , A4 , B1, B3, 19, 22, 23, 3 0 , 3 7 ) and the

charac te r i s t ics of the M a r s a tmosphe re (VM3,

VM4, VM7, VM8)

2 . Basic en t ry capsule s i z e , mass , and per formance

c ha ra c t e r i s t ic s

3 . Physical constraints of e n t r y capsule on the de-

celerator bulk, weight, configuration, a t tach-

ments , e tc .

4. Resulting t ra jec tory p a r a m e t e r s assoc ia ted with

-6-

L

SECTION I - DESCRIPTION OF PROGRAM GER-12842, VOL I

the en t ry capsule (M, h, y, 8, e t c . ) that e s t ab l i sh

the permiss ib le velocity- t ime-d is tance sca l e s

fo r the dece lera tor operat ion

5. Environmental conditions a t deployment (To, q,

g ' s , 8, e tc . ) and operat ion of the dece le ra to r

that es tab l i sh design requi rements f o r per formance

and s t r u c t u r a l integri ty

6 . Dece lera tor charac te r i s t ics as r e l a t ed to pe r -

fo rmance , stabil i ty, weight, and bulk

7. Composite sys t em cha rac t e r i s t i c s

8 . T a r g e t points of Mach number , a l t i tude, angular

excurs ions , and at t i tude r a t e s

The in t e r r e l a t ed f ac to r s and p a r a m e t e r s affecting the application of

aerodynamic dece le ra to r s a r e found to be complex with no d i r ec t o r

p r e c i s e c losed- form solution possible .

effects had to be studied in d i sc re t e , uncomplicated, and o rde r ly fash-

ion and then the s e p a r a t e resu l t s f o r a composite s y s t e m as applied to

representa t ive operat ional cases had to be synthesized.

t ive t rends w e r e established, indicating the m o r e favorable per formance

cha rac t e r i s t i c s , select ions w e r e made . Refined ana lyses and invest i -

gations then w e r e performed leading to the f inal select ion of the con-

cepts and s y s t e m s recommended f o r fu ture full- s ca l e development and

application.

Analysis of the f ac to r s and

Af ter defini-

- 7 -

GER-12842, VOL I

SECTION 11 - ENVIRONMENTAL CONSIDERATIONS

1 ATMOSPHERES AND TRAJECTORIES

The var ious cha rac t e r i s t i c s f o r the model VM (Voyager/Mars) a tmos -

phe res considered in this study a r e l is ted in Table I. F igu res 3 and 4

show the M a r s en t ry t r a j ec to r i e s in the VM7 and VM8 a tmosphere pro-

f i les fo r the en t ry capsule i l lustrated in F igu re 5.

t o r i e s w e r e se lec ted by JPL for the en t ry capsule to es tab l i sh the en-

v i ronmenta l conditions under which the dece le ra to r s a r e requi red to

p e r f o r m successful ly with s t ruc tu ra l in tegr i ty .

loci t ies and angles , and m a s s bal l is t ic coefficients assoc ia ted with the

corresponding t r a j ec to r i e s a r e given in Table 11.

j ec to r i e s (one each in the VM3 and VM4 a tmospheres in F igu re 6 ) w e r e

investigated to de te rmine effects of a tmosphe re var ia t ion for off-design

conditions.

Seven en t ry t r a j ec -

The ini t ia l en t ry ve-

Two additional t r a -

Considerat ion a l s o was given to controll ing f ac to r s such as en t ry cap-

su l e s i ze and configuration, s te r i l i za t ion requi rements , en t ry t r a j ec -

t o r i e s and Mach number/alt i tude ta rge t points.

Although the su r face dens i ty fo r the projected M a r s VM8 a tmosphere is

a l m o s t twice that of the VM7, the inve r se s c a l e height above the tropo-

pause is g r e a t e r by a factor ofabout 2 . 8 ( s e e Table I). F o r a n e n t r y cay-

su l e with a given mass -bal l is t ic coefficient and having the s a m e initial

en t ry conditions, F igu res 3 and 4 show that t he re a r e s h o r t e r t ime s c a l e s

and lower al t i tudes f o r a given Mach number. Higher dynamic p r e s s u r e s

wi l l be assoc ia ted with decelerat ion of the en t ry capsule to the s a m e t a rge t

points (M = 1. Oat 10,000, 20,000, and30,OOO ft) in the VM8 a t m o s p h e r e a s

comparedwi th the VM7.

tabl ished the c r i t e r i a for the des ignin tegr i ty of an in i t ia l - s tage supersonic

dece le ra to r because higher Machnumber per formance is requi red and

Consequently en t ry into the VM8 a tmosphere es-

- 9-

SECTION 11 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

TABLE I - CHARACTERISTICS O F VM ATMOSPHERES

P r o p e r t y

S u r f a c e p r e s s u r e

S u r f a c e dens i ty

S u r f a c e t e m p e r a tu r e

S t r a t o s p h e r i c t e m p e r a t u r e

A c c e l e r a t i o n of g r a v i t y a t s u r f a c e

Compos i t ion

'O2 (by m a s s )

C 0 2 (by vo lume)

N2 (by m a s s )

N2 (by vo lume)

A (by mass)

A (by vo lume)

M o l e c u l a r we igh t

Spec i f i c hea t of m i x t u r e

Spec i f i c hea t r a t i o

Ad iaba t i c l a p s e r a t e

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

I n v e r s e s c a l e height ( s t r a t o s p h e r e )

Cont inuous s u r f a c e wind s p e e d

P e a k s u r f a c e wind speed

Des ign v e r t i c a l wind g rad ien t

- 10-

Symbol

PO

TO

= S

g

M

C

Y

P

r

h T

P

V

V m a x

dv/dh

Dim e n s ion

m b

Ib/sq f t

(gm/cu c m ) 1 ~ 5

( s lugs / cu ft)lO 5

K

R

K

R 2 c m / s e c

f t / s ec 2

m o l - '

c a l /g rn C

K/km

R / 1000 ft

k m

ki lo f t

km- f t - 1 5 x 10

f t / s ec

f t / s e c

f t / s ec /1000 f t

V M3

1 0 . 0

20 . 9

I . 365

2 . 6 5

275

495

200

360

375

1 2 . 3

28 . 2

20 . 0

7 1 . 8

80. 0

0 . 0

0 . 0

31 . 2

0 . 230

1 . 3 8

-3. 88

- 2 . 1 3

19 . 3

6 3 . 3

0 . 0 7 0 5

2 . 15

155. 5

3 9 0 . 0

2

Atmosphe

VM4

10 0

20 . 9

2 . 57

4. 98

200

360

100

180

375

1 2 . 3

7 0 . 0

68. 0

0 . 0

0 . 0

30 . 0

32 . 0

42. 7

0 . 153

1 . 4 3

-5 . 8 5

- 3 . 2 1

17 . 1

56. 1

0. 193

5 8 9

155. 5

3 9 0 . 0

2

p ro f i l e

VM7 ~

5. 0

10. 1

0. 68

1 . 32

275

495

200

360

3 7 5

1 2 . 3

28. 2

20. 0

71. 8

8 0 . 0

0. 0

0 . 0

31. 2

0 . 2 3 0

1 . 38

- 3 . 8 8

- 2 . 1 3

1 9 . 3

63 . 3

0 . 0 7 0 5

2 . 1 5

2 2 0 . 0

556. 0

2

V M8

5 0

1 0 . 4

1 32

2 . 56

200

360

100

180

3 7 5

1 2 . 3

1 0 0 . 0

1 0 0 . 0

0 0

0 . 0

0. 0

0 . 0

44. 0

0. 166

1 . 3 7

- 5 . 3 9

- 2 . 96

18. 6

61 . 0

0. 199

6 . 07

2 2 0 . 0

556. 0

2

I 1

100

90

00

T R A J E C T O R Y 22 - TRAJECTORY El -- -

- TRAJECTORY A4 - - -

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I 1 . 8 1 I I 1 8 I I 8 8 I I I 1 I I

70

60

50.

40

30

m- 0 20 X

k W W LL I

w 10

k O 3

I- -I U

I

'II l o

I I

I 0 1 2 3 4 5 6 7

M A C H N U M B E R

Figure 3 - Trajec tor ies f o r M a r s Atmosphere Entry (VM7 Atmosphere)

- 11-

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

I I I I I I 1 1 I I 1 1 1 I 1 1

~

4 ' 0 1 MACH NUMBER

- T R A J E C T O R Y 19

- - - -TRAJECTORY 8 3

2 3 4 5 6 7

Figure 4 - Tra jec to r i e s f o r M a r s Atmosphere E n t r y (VM8 Atmosphere)

- 12 -

SECTION 11 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

JPL t r a j e c t o r y de s i gna t i o n

A1

A4

B1

B3

19

22

23

30

37

PEii

JF DI

Figure 5 - JPL M a r s En t ry Capsule

TABLE I1 - INITIAL ENTRY CONDITIONS

En t ry velocity, V e

(fps 1

23,000

23,000

15,000

15,000

16,000

16,000

16,000

16,000

23,000

Entry angle, y e (deg)

25

25

15

15

16

16

16

16 '

28

Capsule mass bal l is t i c

p a r a m e t e r , M/C&

(slugs/sq f t )

0. 25

0. 25

0. 5

0. 5

0 .3

0.3

0. 3

0 .3

0 . 3

Atmo s phe r c profile

VM8

VM7 VM7

VM8

VM8

VM7

VM3

VM4

VM8

- 13-

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

1 6 0 -

120 '\

0

c

\

ic

160-

120

L \ 3

' B - ATMOSPHERE VM4 T R A J E C T O R Y 30

---I-- A - ATMOSPHERE VM3

T R A J E C T O R Y 23

-t-

- 14-

I

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOLI

correspondingly higher a e rodynami c p r e s s u r e loads a r e encountered .

Note that higher driving tempera tures a r e assoc ia ted with the VM7 a t m o s -

sphere a t Mach numbers corresponding with those in the VM8.

in the VM7 a tmosphere the resul ts of ana lyses indicate a t rend toward

considerably lower deployment Mach number requirements for f i r s t - s tage

dece lera tors . This t rend minimizes aerodynamic heating effects a s a

c r i t i ca l design factor for the VM7 en t ry cases considered in this study

(see Appendixes A and B).

specified with a blunted cone configuration, as shown in F igure 5 .

capsule has an included angle of 120 deg and the s i ze and mass cha rac t e r -

i s t ics as tabulated i n F igure 5, corresponding with the designated JPL

t ra jec tor ies .

min imum of interface constraints af t of the capsule base so that a s s e s s -

ment of the var ious decelerator configurations was not unduly r e s t r ic tec

by this consideration. However in te rgra t ion forward f r o m the capsule

base to the payload was beyond the scope of the study and this affect is

not reflected.

However,

For this study a basic en t ry capsule was

The

The study allowed substant ia l volume availabil i ty and a

2. DECELERATOR CONFIGURATIONS

An inflatableAIRMATa cone, extending from the base and para l le l to the

bas ic en t ry vehicle forebody angle and r a m - a i r , , self-inflating BALLUTEa

devices i l lus t ra ted in Figure 7 w e r e considered in this p rogram.

cha rac t e r i s t i c s i z e andweight t rends for these devices w e r e found to be in-

dicative df all expandable, pressure- inf la table devices , including parachutes

and other balloon-like configurations that r equ i r e auxi l iary gas inflation

sources . Only the values fo r the represented cases and configuration studied

wil l change.

The t ra i l ing and attached plain-back BALLUTE configurations a r e shown

in F igure 7 with burble fences about 15 deg aft of the maximum BAL-

LUTE d iame te r . T h e r e a r e var ious aerodynamic and s t ruc tu ra l con- s iderat ions for the use of the fence, one of which is to es tabl ish a

The

~~

a TM, Goodyear Aerospace Corporation, Akron, Ohio.

- 15-

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

ATTACHED BALLUTE

TUCKED-BACK BALLUTE

Figure 7 - Decelerator Concepts

point of un i form viscous separat ion near the max imum d iame te r of the

BALLUTE.

sonic speeds, that is, before the c r i t i ca l ( local sonic) Mach number i s

encountered n e a r the max imum BALLUTE diameter , t he re is a possi-

bility of encountering a n a s y m m e t r i c separation effect for a range of

t ransonic Mach numbers near 1. 0.

Although this consideration is associated p r imar i ly with sud-

Additionally the fence provides a substantial portion of the overa l l d rag

of the BALLUTE and can produce the same drag a s a much l a r g e r BAL-

LUTE without a fence. Strength, bulk, and weight requi rements can be

correspondingly l e s s f o r a given d rag effectiveness requirement .

have proved that projections a s high as 10 percent of the BALLUTE

diameter ( r e f e r r e d to a s a 10-percent burble fence) a r e effective.

amount of projection provides a 44-percent i nc rease in relation to the

BALLUTE reference a r e a and a t the same t ime, the des i r ed uni form

viscous separat ion effect is ensured.

T e s t s

This

It is recommended that a similar

- 16-

I I - I I I 8 I i 8 I I I B I I 1 I I I

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

fence be considered f o r incorporation with the tucked-back BALLUTE

configuration.

F igure 8 shows the drag coefficient var ia t ion with Mach number fo r the

configurations i l lustrated in F igure 7.

BALLUTEs and the AIRMAT cone configurations, there w e r e var ious

F o r the attached and t ra i l ing

sources of data fo r reasonable engineering confidence in the drag va r i a -

tions indicated throughout the Mach number range in Figure 8 .

w e r e no comparable data for the tucked-back BALLUTE. However, fo r

T h e r e

this study, a reasonable approximation was possible f o r the drag co-

efficient based on the charac te r i s t ic t r ends fo r blunt, large-angle cone

configurations and the resul ts of var ious BALLUTE development t e s t

p r o g r a m s 1-11

The drag coefficient variation fo r the trail ing BALLUTE shown in Fig-

u r e 8 is assoc ia ted with BALLUTE-to-forebody d iameter ra t ios in the

range f r o m 1. 0 to about 3 . 0.

effectiveness with increasing Mach numbers p r imar i ly is caused by the

reduction of ene rgy in the forebody wake and the wake flow conditions.

Numerous t e s t s have demonstrated the good drag effectiveness and low

oscil lation cha rac t e r i s t i c s of the BALLUTE trai l ing a t a distance with-

in l e s s than four forebody base d iameters - even when the BALLUTE is

t ra i l ing behind a n a symmet r i c lifting forebody a t angles of a t tack up to

30 deg and the forebody has la rge auxi l iary control flaps deflected as

much as 40 deg.

The charac te r i s t ic reduction in drag

Other trail ing dece lera tor configurations fo r supersonic applications,

including all c u r r e n t variations of supersonic parachutes , general ly

have to be positioned fa r ther a f t of the forebody base.

qu i re a l a r g e r d i a m e t e r to develop the equivalent drag effectiveness of

the BALLUTE configuration with a 10-percent burble fence. F u r t h e r -

m o r e , the charac te r i s t ic blunt face of the parachute canopy gives rise

to exaggerated unsteady flow conditions a t supersonic speeds, general ly

causing violent parachute canopy f lut ter and instabil i ty a t off- design

They a l s o r e -

- 17-

SECTION 11 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

I 1 - y 0

I I 0 m

- P P

W 11: 3

LL

W 0 z W LL

W _I

n 3

I- z W 0 rr W

0

'3 1

m

m

a -

W (3 4 n - W > a

I

- k

I

(3 111 0

0 P

0

0

I1

7: I 9 In

I

> i

?

11: b !

I 3 z I u Q I

m

3

~ ~~

Figure 8 - Drag Coefficient Variat ion with Mach Number

- 18-

I I I I I I I I B I I I 1 I I I I I I

I I * I I I I I I I I I I I I 1 I E I I

I

SECTION I1 - ENVIRONMENTAL CONSIDERATIONS GER-12842, VOL I

Mach numbers .

f lated BALLUTE devices during operation p r imar i ly because of (1) m o r e

s teady and uniform flow directed over the s y m m e t r i c a l fo rward portion,

(2) un i form separat ion as a resu l t of the fence, and ( 3 ) st rong damping,

rigidizing, and added m a s s and iner t ia effect of the entrapped inflation

gas a t high stagnation p r e s s u r e (that is, total p r e s s u r e ) ,

This phenomenon i s not assoc ia ted with ram-a i r - in-

The effect of the r i s e r line on the dece lera tor s y s t e m weight was estab-

l ished a s a n important consideration with respec t to the t ra i l ing BAL-

LUTE. This consideration a l so is t rue fo r t ra i l ing parachute decel-

e r a t o r s . The GAC:analyses ( see Appendix A, Volume 11) indicate that

fo r a BALLUTE trai l ing a t a distance of four entry-capsule b a s e d i a m e -

t e r s in the operational environment of in te res t , the weight breakdown

is approximately a s follows: 20 percent fo r the BALLUTE envelope,

33 percent f o r the mer id i an cables , 15 percent f o r the coating (con-

s ider ing both heat insulation and porosity), and 3 2 percent for the r i s e r .

Because of the high percentage of riser weight, a t ra i l ing dece lera tor

m a y weigh more than a n attached dece lera tor even though i t m a y be

s m a l l e r to develop the s a m e total d rag effectiveness.

- 19-

I I I I I I I I I I I I I I I I

I I

a

GER-12842 , VOL I

SECTION I11 - ANALYTICAL CONSIDERATIONS

1 BASIS O F ANALYSIS

To conduct sur face experiments and exploration of Mars effectively,

there will have to be a soft landing with equipment.

able te rmina l dece lera tor f o r a M a r s lander capsule only can be made

by evaluation and a s s e s s m e n t of the constraints of the overa l l mi s s ion

and related sys tems. To obtain a n optimized, expandable, t e rmina l de-

ce l e ra to r , the var ious interrelat ionships of F igu re 2 m u s t be evaluated

within a pa rame t r i c f ramework that allows meaningful tradeoffs.

Selecting an expand-

The requi rement to achieve a ta rge t Mach number and a t a rge t altitude

above M a r s and the evaluation of interrelat ionships in F igure 2 facil i-

tated the understanding of how pa rame t r i c formats and engineering

analysis procedures could be formulated.

w e r e point - mas s t ra jec tory computations, general ized s trength/weight

and configuration ana lyses , d rag pe r fo rmance es t imates , p r e s s u r e dis-

tribution es t imates , mater ia l s investigations, t he rma l ana lyses , and

aerodynamic stabil i ty analyses ( see Volume 11).

The analytical tools used

Decelerator s y s t e m weight has been established as a fundamental factor

i n the application of expandable te rmina l dece le ra to r s .

data, a n integrated tradeoff of dece lera tor weight and en t ry vehicle sys -

t em weight was made .

of allowable Mach number and alt i tude ( o r dynamic p r e s s u r e ) a t deploy-

ment, s i ze , per formance effect iveness , and available operation t imes

to achieve the specified target Mach nurnber/altitude conditions. This

tradeoff a l so took into consideration the vehicle 's

t ics and the operational environments given i n this study.

With appropriate

The dece le ra to r weight was expres sed in t e r m s

physical charac te r i s -

-21-

. _ SECTION I11 - ANALYTICAL CONSIDERATIONS GER-l2842A, VOL I

2 . DECELERATOR WEIGHT RELATIONSHIPS

The weight for a flexible pressure- inf la ted dece lera tor as shown by Fig-

u r e 9 (a l so s e e Appendix A of Volume 11) is related to:

where P is p r e s s u r e ; d, d i a m e t e r ; K a shape fac tor ; and K2, a m a t e r i a l

s t rength fac tor . The p r e s s u r e , P, for a ram-a i r - inf la tab le BALLUTE is

a function of the configuration, dynamic p r e s s u r e , and the flow conditions

of the operating environment. F o r design purposes and s t r u c t u r a l integri ty ,

maximum values of the p a r a m e t e r s corresponding to the deployment con-

ditions general ly a r e employed in any par t icular design application. The p r i m a r y c r i t e r ion is the p r e s s u r e recovery at the ram-air inlets of the de-

v ice .

considerat ion of geometry and position effects, a n a lmos t constant p r e s s u r e

r ecove ry fac tor of 2 . 75 a t the inlets can be achieved f o r deployment Mach

numbers above about 2 . 0.

1’

Numerous t e s t s and ana lyses have shown that by making judicious

-

SHAPE FACTOR 2’ MATERIAL STRE

Figure 9 - Decelerator Weight

- 2 2 - Revised 2 1 October 1966

SECTION I11 - ANALYTICAL CONSIDERATIONS GER-12842, VOL I

In t e r m s of a weight ra t io , i t is shown by Figure 9 that the dece lera tor

weight f ract ion inc reases l inearly with d iameter .

disappointing but well- known effect of the cube/square law fo r s t ruc tu ra l

scaling with increasing size. Additionally, the dece lera tor weight f r ac -

tion is a function of the dynamic p r e s s u r e o r squa re of the Mach number

and is related to the external sur face p r e s s u r e f r o m the aerodynamic

loads that requi res support by the in te rna l p r e s s u r e .

Thus, the dece lera tor weight r e su l t s w e r e developed f r o m s ta t ic a e r o -

dynamic loading relationships with empir ica l ly determined, quas i - s ta t ic

load, tempera ture , and design fac tors employed to account fo r operat-

ing environmental effects and ma te r i a l cha rac t e r i s t i c s . The validity of

this approach has been demonst ra ted by the r e su l t s of this study and has

led to optimum designs of sys t ems with min imum prac t ica l weight.

s ider ing dynamic loading effects, additional weight advantages a r e

gained by delaying the decelerator device deployment to lower dynamic

p r e s s u r e conditions, when time and distance sca l e s pe rmi t , fo r the

following reasons :

This fact re f lec ts the

Con-

1.

2 .

3 .

4.

Energy requirements to deploy and e r e c t the de-

ce l e ra to r a r e reduced since the bas ic vehicle sys -

t e m i s decelerating iner t ia l ly a t a lower r a t e

Snatch loads on the dece lera tor device, support-

ing s t ruc tu re , and vehicle as a r e su l t of lower

relat ive iner t ia l velocit ies a r e reduced

Deployment opening shock and inflation loads as

a r e su l t of lower dynamic p r e s s u r e s a r e reduced

Peak heat flux, integrated heat load, and maxi-

m u m tempera ture r i s e on exposed su r faces of the

dece lera tor a r e reduced because of the lower de-

ployment velocity and shor t e r t ime sca l e s of opera-

tion to a t ta in lower specified t a rge t alt i tude/Mach

number conditions

-23-

I 3 .

SECTION I11 - ANALYTICAL CONSIDERATIONS GER-12842, VOL I

Before specific r e su l t s a r e presented , i t i s des i rab le to es tab l i sh how

the dece lera tor s i ze was de te rmined ( see Section V of Volume 11).

u r e 10 i l lus t ra tes the s i x bas i c s t eps i n the graphic ana lys i s procedure

that lead to a f i r s t approximation determinat ion of the dece le ra to r s i z e

for achieving the t a rge t Mach number/al t i tude.

Fig-

-24-

I I .

c W 0 3

t- -I

t

a

I l l .

c w

t

a

0 3

i- -I

T A R G E T MACH NO.

1 e

t-7 / MACH NUMBER, (M ) I 3

n T A R G E T MACH NO.

n

( C D A )

(CDA)

(C A)

V

D

T

I .

c W 0 3

t- -I Q

k

(cD

CCD

(c D O P E R A T I N G

A )

A)

A)

V

D

T

(CDA)

(CDA)

P E R C E N T OF T

V

V E H I C L E DRAG A R E A

D E C E L E R A T O R D R A G

X (CDA) V

= 1 0 0 P E R C E N T

A R E A

V A L U E

MACH NUMBER

T A R G E T T R A J E C T O R Y 19

A L T I T U D E S A1

A T MOS P H E

M = 1.0 T

M = 3.0 I

P E R C E N T O F ( C D A I / (CDA)

T V (C,A)

R E VM8

P E R C E N T O F - " T

J

T R A J E C T O R Y

M = 1.0 T

VM8

19

( c D N = 281.5 SQ FT V

/ I N I T I A L MACH NUMBER, M,

~ SECTIOV 11; - ANALYTICAL CONSIDERATIONS GER-12842 , V O L I

V I .

0 0

W I- W z

0 [L 0 I-

[L W -I

d

5

a

I V .

A T T A C H E D E A L L U T E

ATMOSPHERE VM8

TRAJECTORY 19

M = 1.0 T

hT = 20,000 FT

A T T A C H E D B A L L U T E

I

MACH NUMBER V .

E l 0

I N I T I A L MACH NUMBER, M I

F i g u r e 10 - Six Steps fo r Determing Decelera tor Size (All Values are Typical)

-26-

GER-12842, VOL I

SECTION IV - RESULTS O F ANALYSIS

1. TRAJECTORIES CONSIDERED

The A l , A4, and 19 t ra jec tor ies specifically a r e considered he re but

the analysis procedures and charac te r i s t ic t rends indicated a r e appro-

pr ia te to all the t ra jec tor ies ( s e e Volume 11). Note that the A1 and A4

t ra jec tor ies have a M/CDA of 0. 25 and a r e assoc ia ted with a higher

init ial entry velocity and s teeper en t ry angle ( f rom Table 11,

23, 000 fps and y e = 2 5 deg)when compared with the other t r a j ec to r i e s ,

except for the 37 t ra jec tory that has the s a m e velocity but a s t eepe r

init ial entry angle of 28 deg and a n M/CDA of 0 .3 . These en t ry con-

ditions m a y be assoc ia ted with lower accu racy constraints for e i ther

orbiting o r flyby en t ry modes of the entry capsule. F o r the cases con-

s idered in this study and a s shown by the t r a j ec to r i e s of F igu res 3 and

4, the sever i ty of environmental conditions encountered a t correspond- ing alt i tudes in a tmosphe re VM8 a r e affected m o r e substantially by

init ial en t ry conditions than by the mass-ba l l i s t ic pa rame te r .

example compare the A1 and 19 en t ry cases a t the alt i tude of30,OOO ft.

It should be recognized that the resu l t s shown l a t e r pertaining to the

A1 t ra jec tory indicate l e s s favorable weight f ract ions for f i r s t - s t age

dece lera tors to achieve the s a m e ta rge t Mach number/alt i tude points

as compared with the 19 t ra jectory.

init ial en t ry velocity (V = 16, 000 fps) and a lower en t ry angle (y =

16 deg) with a higher mass-ba l l i s t ic p a r a m e t e r (M/C A = 0. 3) .

V = e

F o r

The 19 t r a j ec to ry has a lower

e e

D

2. DECELERATOR SIZE

The s ix-s tep ana lys i s procedure was used to develop Figures 11 and

12, which establ ish the decelerator s ize r equ i r emen t s to r e t a r d en t ry

capsules in the A l , A4, and 19 t r a j ec to r i e s to a t a rge t Mach number

-27-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

40

36

32

2E

2r - k W W L. - 0 0

U W + W I

0 K 0 k

K W -1 W u W 0

I!

a

I

T R A J E C T O R Y A1

ATMOSPHERE VM8

MT 1.0

hT 20,000 FT

I-- T R A J E C T O R Y A4

ATMOSPHERE VM7

- - 1 .o M T

- T R A I L I N G B A L L U T E --- A T T A C H E D B A L L U T E - 0- T UC KE D-BA C K B A LL U TE - -0 AlRMAT C O N E *

OPTIMUM I N I T I A L O P E R A T I N G MACH NUMBER

I 1 I

2 3 4 5 6 7 8

MACH NUMBER

Figure 1 1 - Decelera tor Size Requi rements (Tra j ec to r i e s A1 and A4; Atmospheres VM7 and VM8)

- 28-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

M = 1.0 T

I - - - A T T A C H E D B A L L U T E I ( I _- - TUCKED-BACK B A L L U T E

-. - AIRMAT CONE

O P T I M U M I N I T I A L O P E R A T I N G M A C H N U M B E R

I

Figure 12 - Decelerator Size Requirements (Tra jec tory 19 and Atmosphere VM8)

-29-

of 1. 0 n e a r target a l t i tudes of 20 , 000 and 30 ,000 f t ( s e e Section VI of

Volume 11).

effectiveness a t the corresponding Mach numbers on the a b s c i s s a sca l e .

In o ther words, fo r the f i r s t approximation of dece le ra to r s i z e , t ime

sca l e s f o r dece lera tor deployment and inflation w e r e not requi red to be

ref lected i n these r e su l t s . Note, however, that f o r the corresponding

Mach numbers in the f igures in this sec t ion i l lus t ra t ing the c h a r a c t e r -

i s t i c s of the dece le ra to r s t he re is a s l ight ly higher Mach number (about

5 percent ) and a higher dynamic p r e s s u r e (about 10 percent ) a t which

the dece lera tor device i s deployed ini t ia l ly and begins to inflate ( s e e

I tems 16 and 17 of Tables A- I through A-XI of Appendix A). F igu res 11

and 12 show the t rend to asymptot ic values of dece le ra to r s i z e as Mach

number is inc reased .

The dece le ra to r s w e r e defined a s developing the i r ful l -drag

Thus, this study has pointed out that i n re la t ion to the s i z e of a dece l -

e r a t o r , t he re is a n upper p rac t i ca l l imi t to the ini t ia l operat ing Mach

number . Above this l imi t t he re is no apprec iab le reduction i n decel-

e r a t o r s i ze to achieve lower specified t a rge t Mach number/al t i tude

points fo r the t r a j e c t o r i e s considered in this study.

cu rves assoc ia ted with the t a rge t point Mach number of 1 . 0 and the

20 , 000-ft al t i tude fo r t r a j ec to ry 19, the s m a l l e r dece le ra to r s i z e s a r e

indicated because of the increas ing densi ty of the a tmosphe re .

In comparing the

3 . DECELERATOR WEIGHT

F igures 13 and 14 p resen t the percent of d e c e l e r a t o r weight to total

en t ry capsule weight for the fou r dece le ra to r configurations in t r a j e c -

t o r i e s A l , A4, and 19. The r e su l t s w e r e obtained by the ana lys i s pro-

cedure in Appendix A of Volume 11. F o r these f igu res the dece le ra to r

s t rength requi rements a r e predicated on the u s e of dac ron a s s u m e d to

be operating a t a n elevated t e m p e r a t u r e of 350 F.

design f ac to r of 2. 0 a l s o is re f lec ted i n the r e s u l t s presented .

A m a t e r i a l s t r eng th

When i t i s possible to a t ta in specif ied t a r g e t a l t i tude/Mach number con-

ditions within physical cons t ra in ts and within al lowable t ime and d is tance

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

1 1 I 1 1 1 I I I 1 1 1 I 1 I I I

3 6

32

28

24

20

- 5 16 W U II: W a - 3+ \ 12 0

\ / /

/.4' / 1 '.:>. 0

3

I

W % _1

t- 0

0

k-

c,

a

?

L 0 I-

K W -I W u W

a

n

SECTION IV - RESULTS O F ANALYSIS GER- 12842, VOL I I * -

I 1 I ' I I t I I 1 I 1 I 1 I; t 1 R

T R A J E C T O R Y A1

ATMOSPHERE VM8

M = 1.0 T

T R A J E C T O R Y A 4

ATMOSPHERE VM7

- M = 1.0 T

-e-- - - -- 1 2 3 4 5 6 7

MACH NUMBER

~ ~

Figure 13 - Decelerator- to-Total Weight (Tra j ec to r i e s A1 and A4; Atmospheres VM7 and VM8)

-31-

32

28

24

20

- k

W U U W

z 16

a - I- 3 “o 12

3

I

W 3 -I d I- O

0

i 2

?

z 0 I- 4 [L W -I W V W 0

/ T R A I L I N G B A L L U T E I

. !

-_--- MT :- l o

h T = 30,000 F T

--- - A T T A C H E D B A L L U T E

---- TUCKED-BACK B A L L U T E

-e- A I R M A T C O N E

@ O P T I M U M I N I T I A L O P E R A T I N G MACH NUMBER

N O T E

BASED O N D A C R O N

A T 350 F

E 11 1 1 I 1 1 1 I 1 1 I I 1 I 1 I I R

.. SECTION IV - RESULTS OF ANALYSIS GER-12842, VOL I

1 2 MACH NUMBER

3 4 5 6 7

Figure 11 - Decelera tor - to-Tota l Weight ( T r a j e c t o r y 19 and Atmosphere VM8)

-32-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

sca l e s , F igures 11 through 14 indicate that i t is des i rab le to accept a

l a r g e r dece lera tor diameter and delay operation of the device to a cor -

responding lower Mach number. This consideration leads to the t rend

of a r r iv ing a t a minimum percentage of dece lera tor - to-total s y s t e m

weight and corresponding optimum init ial operating Mach number .

t r a j ec to ry 19 in Figure 14 and the ta rge t conditions of Mach number =

1. 0 and altitude = 20, 000 ft , the s a m e t rends a r e indicated. However

as a r e su l t of the extended available t ime and dis tance sca l e s andh ighe r

a tmosphe re density, the values for the dece lera tor s ize , weight f ract ion,

and operational Mach number a l l a r e reduced substantially as compared

with the requi rements for the 30, 000-ft t a rge t alt i tude case . The in te r -

action of Mach number effect (that i s , dynamic p r e s s u r e ) on the decel-

e r a t o r s t rength and weight requirements has a compounding effect.

F o r

4. TEMPERATURE AND MATERIAL CONSIDERATIONS

Figure 15 has been developed by the analysis procedure of Section IV

of Volume I1 to indicate the degree of validity in choosing dacron when

operating a t a tempera ture of 350 F for the dece lera tors analyzed and

in leading to the resu l t s presented in F igures 13 and 14 for t r a j ec to r i e s

A1 and 19. The the rma l requirement curves for dacron and Nomex for

t r a j ec to ry A1 rep resen t the envelope fabric weight p e r unit area re -

quired to l imit the total t empera ture r i s e to 350 F with dacron and600 F

with Nomex. These curves cor respond with the dece lera tor s i zes in

F igures 11 and 12 that begin effective operation a t the corresponding

Mach number on the absc issa sca le .

sul ts f r o m the local heat flux and integrated heat load corresponding

with the velocity- t ime-dis tance sca l e s (appropriate to init ial operating

conditions fo r the dece lera tors ) to achieve the t a rge t points of M

1. 0 and hT = 20, 000 ft.

a s s u m e d that the local heat flux is 0. 30 of the stagnation point value.

The m a t e r i a l t e m p e r a t u r e r e -

=

The analyses ( see Section I1 of Volume 11) T

Boundaries for both 30 , 000- and 20,000-ft t a rge t alt i tudes fo r t ra jec-

to ry 19 have been included in F igu re 15 to indicate the effect of a lower

-33-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

ta rge t altitude requirement . F o r the lower ta rge t alt i tude, t he re a r e

assoc ia ted lower opt imum init ial operating Mach number requi rements

with the resulting f a c t that aerodynamic heating effects a r e minimized .

At the higher init ial operating Mach numbers for this ta rge t alt i tude,

l a r g e r values fo r the fabr ic unit weight a r e required as a r e su l t of the

extended time sca l e s of operation and consequent i nc rease in total heat

load in addition to the effect of the higher values of Mach number . To

develop the thermal requi rement cu rves , the heat absorbed by the de-

ce le ra tor ma te r i a l was a s s u m e d simply to be that of i t s heat capacity.

In F igure 15 a r e the curves of dece lera tor envelope fabr ic weight p e r

unit a r e a for the attached and t ra i l ing BALLUTE dece le ra to r s estab-

l ished by aerodynamic loading requi rements . T h e r e a r e symbols for

the other configurations a s de te rmined a l s o by the aerodynamic load-

ing encountered at the corresponding ini t ia l operating Mach number to

achieve the desired ta rge t point conditions.

t a rge t conditions of M = 1. 0 and hT = 2 0 , 0 0 0 ft , i t is shown that the

u s e of dacron a t a 3 5 0 - F "s ta t ic" t e m p e r a t u r e fo r the AIRMAT cone

(initially operating at the indicated opt imum Mach number f r o m Fig-

u r e s 13 and 14) i s conservat ive.

assumpt ion of dacron a t 350 F is quite accu ra t e ; f o r the t ra i l ing and

tucked-back BALLUTEs , the assumpt ion is opt imist ic .

F o r t r a j ec to ry A1 with

T

F o r the attached BALLUTE, the

It is pointed out h e r e that the s ta t ic strength/weight ana lys i s and the

the rma l analysis did not include provision f o r coating weight. Some

coating m u s t be provided in any event to ensu re min imum acceptable

leakage ra tes to maintain the des i r ed p res su r i za t ion within the decel-

e r a t o r envelope.

a r e a l s o good heat insulating ma te r i a l s ( s e e Section I11 of Volume 11).

A nominal coating thickness of about 0. 01 psf of Vitron o r Neoprene

will provide a net porosi ty of about 0. 02 cu ft /sq f t / sec , which i s a n

acceptable value based on exper imenta l r e s u l t s f o r the upper values

of p r e s s u r e ratios and operating envi ronment encountered in this study.

Typical coating m a t e r i a l s employed fo r this purpose

0.15 I

0.1

- I- O 0 ll.

W r 3 a

s: K W

cn z 3 0

a n

a a - \ z 4 W U 4

z 2 K W

I- I

W 3

k

a

13

0.2

0.15

0.1

0.05

M A C H N U M B E R

35

RY A1

- - AERODYNP L O A D R E Q U I R E M E N T

3 IACH NUMBER

~ SECTION IV - RESULTS O F ANALYSIS GER-12842, V O L I

L O A D R E Q U I R E M E N T

T R A I L I N G B A L L U T E

i+,;OMEX A T 60: F 1 + - D A C R O N A T 350 F

% T R A I L I N G B A L L U T E

0 A T T A C H E D B A L L U T E

+ TUCKED-BACK B A L L U T E

A AIRMAT CONE

A h = 20.000 FT AND M = 1.0

h = 30,000 FT AND M = 1.0

T T

T T

- DACRON A T 350 F

- - - NOMEX A T 600 F

Figure 15 - Aerodynamic and Therma l Effects on Decelera tor Envelope (Tra j ec to r i e s 1 9 and AI)

4% - 3 4 -

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

F igures 16 through 19 present curves to es tabl ish a m o r e refined e s -

t imate fo r the minimum required dece lera tor envelope unit weight that

would be compatible with both the aerodynamic heating and aerodynamic

loading environment fo r the seve ra l en t ry cases considered in this study

(also s e e Section VI of Volume 11). Each figure i s assoc ia ted with the

dece lera tor configurations that provide decelerat ion of the basic en t ry

capsule to % = 1. 0 nea r the ta rge t alt i tude specified on the f igures .

each f igure i s the callout "optimum Mach no. , I' which is associated

with a minimum percentage of dece lera tor - to- total en t ry capsule weight.

In

On the ordinate in these figures is the callout "min imum prac t ica l

weight", which is the minimum weight of the envelope fo r each of the

dece lera tor types. The thermal requi rement curves a r e l imited to a

maximum tempera tu re of 450 F for dacron and 700 F for Nomex.

symbols fo r each decelerator located on the "opt imum Mach no. I ' line

cor respond to the envelope ma te r i a l thickness requi red to sustain the

aerodynamic loading a t the indicated tempera ture .

p rac t ica l weight" includes provision fo r a coating of 0. 01 lb/sq ft of

Neoprene o r Vitron to give the dece lera tor envelope a low value of po-

rosi ty .

specific heat as the envelope ma te r i a l , which i s a valid assumpt ion ( see

Section I11 of Volume 11).

The

The "minimum

F o r this study i t is a s sumed that the coating has the s a m e

The fabric weight pe r unit a r e a is in re ference to the thin envelope of

the dece lera tor device.

to total dece lera tor weight (see Appendix A of Volume 11) is nominally

20 percent for the t ra i l ing BALLUTE, 38 percent for the attached BAL-

LUTE, and 10 percent fo r the tucked-back BALLUTE.

MAT cone, the envelope compr i se s about 67 percent of the total ex-

pandable dece lera tor weight.

the period of the significant heat pulse is of the o r d e r of 5 s e c ( see

Section I1 of Volume I1 and Figures B-1 through B-6 in Appendix B).

In this in te rva l the speed of the en t ry capsule will have been reduced

The proportion of dece lera tor envelope weight

F o r the AIR-

F u r t h e r m o r e for the cases under study,

-37-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

I- O 0 LL W K Q 3

8 K W

m 0 Z 3 0

a

a a

a

- \ z

W K Q

I- I

W 3

\

!2

I

k 0 0 LL W K Q 3

8 0: W

m 0 Z 3 0

Q

3

W K a

I

W 3

a

a - \-

a

.. 6 :

0.3

0.2

0.1

0

MACH NO.

0.2

0.1

0

Y 2 3 4 5 6 7 I N I T I A L MACH NUMBER, MI

I I I

,MACH NO.

A I R M A T C O N E

I I

~ . . . . . . . . . . - . . . P R A C T I C A L

2 3 4 5 6 7

I N I T I A L MACH NUMBER. MI

~ ~ ~~~

Figure 16 - Minimum Decelera tor Envelope Unit Weight (Tra jec tory A l , hT = 20,000 ft , Dacron)

- 3 8 -

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

0.2

- I- O 0 LL W U 3 a

5: U W ; 0.1 0 Z 3 0 a a

d

a

'3

3 0

- \ %

W K

I- I

W

\

0.2

I- 0 0 LL W U 3 a

5: U W

u) 0 z 3 0

a 0.1

a a

d

a

'3 S o

- \ 3

W U

I- I

W

\

I TRAILING B A L L U T E

MINIMUM PRACTICAL 6ooF

MACH NO.

A T T A C H E L IALLUTE

0 P T IMUM MACH NO

00 F b MINIMUM PRACTICAL WEIGHT

4

- TUCKED-BACK B A L L U T E

400 F. 500 F, 600 F,

MINIMUM PRACTICAL

6 7 3 4 5 6 INITIAL MACH NUMBER, MI IN IT IAL MACH NUMBER, M,

Figure 17 - Minimum Decelerator Envelope Unit Weight (Tra jec tory A l , hT = 20,000 f t , Nomex)

-39-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

0.3 I T U C K E D - B A C K B A L L U T ~ I I

L N J R I I I-

- 40-

2 3 4 5 IN IT IAL MACH NUMBER. MI

A T T A C H E D B A L L U T E m OPTIMUM MACH NO. I I

I I AlRMAT C O N E 1

OPTIMUM MACH NO.

2 3 4 5 IN IT IAL MACH NUMBER, MI

Figure 18 - Minimum Dece le ra to r Envelope Unit Weight (Tra j ec to ry 19 , h - 20, 000 f t , Dacron) T -

I- O 0 LL W [L

3 a

s:

3

(L W a

Z 3 0 a a

d

- \ z

w U a I- I u W 3

\

-

- I- O 0 LL W K 3 a

U W

v) 0 Z 3 0

a

a a

d

- \ 3

W K a I- S

W B

\

!?

0.3

0.2

0.

0

TRAILING B A L L U T E 1

/ I l l

0.3 T U C K E D - B A C K B A L L U T E

0.2

0.1

n

MINIMUM PRACTICAL WEIGHT

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

d 8 1 I 1 i 1 1 I i t i I 8 8 8 I

I

- 2 3 4 5 6 7

I N I T I A L MACH NUMBER, M,

A T T A C H E D B A L L U T E I I 1

MINIMUM P R A C T I C A L WEIGHT

I I / / f

A I R M A T C O N E I I

MINIMUM P R A C T I C A L

2 3 4 5 6 7 I N I T I A L MACH NUMBER, MI

Figure 19 - Minimum Decelerator Envelope Unit Weight (Trajectory 1 9 , hT = 30 ,000 ft, D a c r o n )

-41-

SECTION IV - RESULTS O F ANALYSIS GER-12842AY VOL I

significantly and the corresponding aerodynamic loads will be smaller

by the t ime the m a t e r i a l r eaches the a s s u m e d elevated operat ing tem-

pe ra tu res used in this study (note F igu res 16 through 19). Thus, i t is

indicated (see I tem 1 1 , Tables A-I through A-XI of Appendix A) that

fo r the dece lera tor envelope with coating thickness based on acceptable

leakage ra te and heat insulation, reasonable dece lera tor weight f r a c -

tions can be obtained.

5. E F F E C T O F TARGET MACH NUMBER VARIATION

The determinat ion of how the dece le ra to r s i z e and t a rge t alt i tude a r e

affected by the ta rge t point Mach number as i t v a r i e s f r o m 0. 7 to 1 . 5

is important as relating to s i ze and per formance operating to le rances .

F igu res 2 0 and 2 1 i l lus t ra te these effects for t r a j ec to ry 19 . Cons ide r -

ing the effect on s i ze (F igu re 20), increas ing the t a rge t Mach number

to 1. 4 reduces the requi red total s y s t e m d r a g a r e a by about 100 p e r -

cent f r o m the value requi red a t Mach 1. 0.

r e f e rence point (the z e r o value on the ordinate sca le of F igu re 20) for

t r a j ec to ry 19, the percentage of total s y s t e m d rag a r e a to the en t ry

capsule drag a r e a i s requi red to have a nominal value of about 500 p e r -

cent to attain a n M

1. 4 a t 30 , 000 ft, the percentage of dece le ra to r d r a g a r e a to the en t ry

capsule drag a r e a can be reduced to about 400 percent . In this c a s e ,

this reduction i s the s a m e a s decreas ing the dece le ra to r d i ame te r by

about 10 percent for a n ini t ia l operat ing Mach number of 3 . 0.

t rend is for a s m a l l e r reduction in s i ze with higher init ial operat ing

Mach number.

At the Mach number 1. 0

- T - 1. 0 a t 30, 000 f t . If the MT i s i nc reased to

The

On the other hand f o r a lower t a rge t Mach number of 0 . 7 , a 10-per -

cent i nc rease in dece le ra to r s i ze is indicated.

while assuming a constant value of d r a g coeff ic ient fo r the s y s t e m ,

which is optimistic compared with the c h a r a c t e r i s t i c lower d rag co-

efficient of bodies a t subsonic veloci t ies .

numbers , the effect of the ini t ia l operat ing Mach number is nominal.

This i n c r e a s e is made

At the subsonic t a rge t Mac11

-42 - Revised 21 October 1966

160

120

80

40

0

I1 -80 t- E + 4

I- - 0 -120 u - -

\ I- - a 0 u

Y

- 1 6 0

SECTION IV - RESULTS OF ANALYSIS GER-12842, VOL I 1 . I 1 1 I 1 I 8 I I I I I I I I I I

0 . 6 0 .E 1 .o 1.2 1.4 1.6

T A R G E T MACH NUMBER, M T

Figure 2 0 - Change in Percent Total Drag Area (Tra j ec to ry 19 and Atmosphere VM8)

- 4 3 -

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

- 8,000 I

t W W LL - s - 10,000 W u z 6 x u 0 3

- 12,000

I i I

I

I

I- -I 4 - 1 4 , 0 0 0

0 . 6 0.8 1 .o 1.2 1.4 1.6

T A R G E T MACH NUMBER, M I T

Figure 21 - Change in Altitude with Variat ion of T a r g e t Mach Number f r o m 1. 0 (T ra j ec to ry 1 9 and Atmosphere VM8)

- 44-

I I I I I I I I I 1 I 1 I I I I I I I

SECTION IV - RESVLTS O F ANALYSIS GER-12842, VOL I

The effect of ta rge t point Mach number variation on alt i tude shows that

i f the ta rge t Mach number is allowed to inc rease above 1 . 0, there i s

a n incrementa l gain in target alt i tude.

d e c r e a s e s with decreasing values of ta rge t point Mach number .

Conversely the t a rge t alt i tude

A higher init ial operating Mach number resu l t s in a n additional gain in

alt i tude p r imar i ly because the higher Mach number is a l so associated

with a higher init ial operating altitude ( see Step 1 in Figure 10). F o r

lower ta rge t Mach numbers a higher init ial operating Mach number

causes loss in alt i tude. This loss occurs because of the lower air den-

s i ty corresponding with the higher alt i tude a t which the re ference ta rge t

Mach number of 1 . 0 is attained and because the required dece lera tor

d rag a r e a corresponding with the higher init ial operation Mach number

a l s o i s sma l l e r .

F igure 22 i l lus t ra tes the t rend of dece lera tor - to- total en t ry capsule

weight as a function of target Mach number variation with ta rge t altitude

as a p a r a m e t e r fo r t ra jec tory 19.

the absc i s sa sca le i s the Mach number to which the en t ry capsule de-

ce l e ra t e s without an auxiliary dece lera tor . F o r t r a j ec to ry 1 9 i t is in-

dicated that fa i r ly low values of subsonic Mach number can be attained

fo r dece lera tors weighing l e s s than 10 percent of the total en t ry capsule

weight.

t r a j ec to ry 19, substant ia l weight penalt ies a r e incur red r ega rd le s s of

ta rge t a1 t i tude.

The intersect ion of the curves with

To achieve ta rge t Mach numbers of l e s s than about 0. 4 fo r

- 45-

SECTION IV - RESULTS O F ANALYSIS GER-12842, VOL I

I I I

h = TARGET ALTITUDE T

r- 0 I

w % J

I- O

0

U 0 l-

U W -I W u W 0

a

? ?

a

T A R G E T MACH NUMBER, M T

tl ---I-

1.2 1.4 1 .6 1.8 2.0

Figure 22 - Variation of Dece lera tor Weight with T a r g e t Mach Number (Tra j ec to ry 1 9 ; Attached BALLUTE)

-46-

I I 1 I I I I 1 I I I I I 1 1 I I I I

~~ ~~ ~

GER-12842, VOL I

SECTION V - SYSTEM COMPARISONS

1. BASIS FOR COMPARISON AND SELECTION

The compar ison and subsequent selection of dece lera tor configurations

and their su i tab le a r e a s of application for final study and ana lys i s w e r e

facil i tated by a tabulation scheme.

with each of the four decelerator configurations fo r the var ious en t ry

c a s e s under study w e r e evaluated as shown in Tables A - I throughA-XI

in Appendix A.

that es tabl ish rea l i s t ic total dece lera tor s y s t e m weight es t imates and

that w e r e n e c e s s a r y for use with the dynamic computer ana lyses .

Thir ty separa te f ac to r s assoc ia ted

The tabulation includes those engineering design fac tors

Seventeen cases w e r e selected as indicated in Table I11 below, for r e -

f ined point - ma s s t ra j e c to r i e s t ha t inc o r po r a t ed a t r a n s i en t ,

analysis p r o g r a m to determine m o r e real is t ical ly the t e m p e r a t u r e to

which the fabr ic of the dece lera tor envelope will be subjected.

u r e s B-1 through B-6 in Appendix B show the r e su l t s of the refinedpoint-

m a s s t ra jec tory computations and t rans ien t heating calculations.

heating

.Fig-

TABLE I11 - CASES SELECTED FOR EXTENDED CONSIDERATION

Decelera tor Configurations

numb e r (ft x 103) TB AB TBB AC

Targe t t r a j ec to ry alt i tude -c------

X X 20 I

20 ' x X X

19 20 X X X X

22 30 X X X X

23 30 X X

30 20 X X

- 47-

I SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

The select icn of the en t ry cases in Table I11 for extended ana lyses was

considered appropriate s ince these cases encompass the broad range

of p a r a m e t e r s assoc ia ted with the study, including: (1 ) mass bal l is t ic

p a r a m e t e r , s i ze , and weight of en t ry capsule , ( 2 ) in i t ia l t r a j ec to ry con-.

dit ions, ( 3 ) Mars a tmosphere prof i les , and ( 4 ) the four bas ic expandable

dece le ra to r configurations. Thus, a reasonable a s s e s s m e n t of the e f fec t

these p a r a m e t e r s have on the cha rac t e r i s t i c s of expandable t e r m i n a l

dece le ra to r s could be made .

s ince all the dece le ra to r configurations w e r e evaluated fo r these two

t r a j e c t o r i e s , including the dynamic s tabi l i ty ana lyses . These t r a j ec -

t o r i e s a r e considered the m o r e appropr i a t e fo r the ea r ly M a r s lander

mis s ions and, as wil l be d i scussed , show that expandable t e r m i n a l de-

ce l e ra to r s can provide des i r ab le s y s t e m pe r fo rmance with reasonable

weights within cu r ren t expandable dece le ra to r technology.

T r a j e c t o r i e s 1 9 and 2 2 w e r e emphas ized

The refined point-mas s t r a j ec to ry computations included provis ion fo r

a l inear i nc rease in dece le ra to r d rag a r e a f r o m init iation of deploy-

ment to full inflation during a n in te rva l of 1 . 5 s e c .

inflation in te rva l and l inear d rag a r e a var ia t ion w a s based on exper i -

ence with r a m - a i r inflated BALLUTEs for the Mach number and dy-

namic p r e s s u r e range of c u r r e n t i n t e r e s t .

off considerations of a minimum d e s i r e d t ime to achieve ful l -drag effec-

t iveness and low opening shock and to avoid m a t e r i a l fatigue f a i lu re as

a r e su l t of f lut ter during the inflation in te rva l .

The choice of this

This choice includes t r ade -

With the ram-a i r - inf la ted configurations, the s i z e and number of the

inlets m u s t provide the requi red m a s s flow into the dece le ra to r envel-

ope consistent with the dece le ra to r i n t e rna l volume and the inflation

in te rva l of 1. 5 s e c .

gas inflaticn sou rce , gas p r e s s u r e , gas volume, valve s i z e s , and

valve numbers a l s o m u s t be compatible wi th the inflation in t e rva l of

1. 5 s e c .

For the 120-deg AIRMAT cone with a n auxi l ia ry

Layout drawings of se lec ted dece le ra to r /veh ic l e combinations fo r the

- 48-

I I 1 1 1 I I I

I P I I I I I D

a

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

four dece lera tor configurations under study w e r e made a s shown in Fig-

u r e s 23 through 26.

ment , deployment requirements , and constraints was gained. Addi-

tionally rea l i s t ic weight es t imates fo r the anc i l la ry equipment assoc ia ted

with these i tems w e r e obtained as tabulated in these f igures .

packaged volume requirements a r e not beyond the range of prac t ica l

considerations ( see Item 13 of Tables A - I through A-XIinAppendix A) .

F r o m these a n a s s e s s m e n t of the packaging, attach-

Note that

As i l lust rated in the layout drawings of F igures 23 through 26, Marmon

c lamps accompl ish attachment and separat ion functions of the var ious

dece lera tor devices and associated equipments.

significantly l ighter and has l e s s bulk with higher reliabil i ty and uni-

formi ty in accomplishing separation functions. F u r t h e r m o r e , this

a t tachment method is suitable for all the dece lera tor concepts includ-

ing the trail ing dece lera tors .

the capsule base and the confluence point of the r i s e r a r e attached to

the ring as i l lustrated in Figure 23.

men t s a r e s imple with a minimum of pa r t s .

for this method of attachment fur ther lend themselves to simplifying

the s ter i l izat ion of this assembly.

The Marmon c lamp is

In this ca se the suspension l ines between

Additionally the a s s e m b l y requi re -

All of these cha rac t e r i s t i c s

2. DYNAMIC ANALYSIS

Dynamic stabil i ty charac te r i s t ics for each of the four dece lera tor con-

figurations for the 19 and 22 t r a j ec to r i e s w e r e analyzed.

of attached dece lera tor configurations, a s ix-degree-of - f reedom com-

puter p rogram was used (see Appendix B of Volume 11) for the formu-

lation of the dynamic stability analysis .

two additional degrees of f reedom w e r e included.

In the case

F o r the t ra i l ing BALLUTE

F igures 27 and 28 show the oscil lation cha rac t e r i s t i c s for each of the

four bas ic dece lera tor configurations a s applied to the 19 and 22 t r a -

jec tor ies .

kinematic coupling between rolling velocity and angle of a t tack caused

In the case of the t ra i l ing dece le ra to r s , the effect of the

- 49-

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

5 0 -

the capsule to continually diverge to l a rge angles of a t tack and coning

angles fo r both the 19 and 22 t r a j ec to r i e s .

the s y s t e m dynamics with the t ra i l ing dece lera tor is not adequate and

should be studied i n g r e a t e r detai l i n fu ture p rograms .

plitude of oscillation f o r the 2 2 t ra jec tory is caused by the reduced

damping moments i n the lower densi ty of the VM7 a tmosphere as com-

pared with the VM8 a tmosphere .

The p resen t descr ipt ion fo r

The l a r g e r am-

The drag force and moment of the t ra i l ing dece lera tor has the na tura l

effect of providing stabil ization f o r the composite capsule/decelerator

sys tem. However, because of kinematic ( rol l -yaw) coupling effects

there is considerable divergence in angle of a t tack of the composi te s y s -

tem.

the kinematic coupling effect.

ing velocity of the en t ry capsule when the dece le ra to r s a r e deployed

s ince the moment of iner t ia in ro l l has been inc reased .

s y s t e m rolling velocity is reduced a small amount s ince conservat ion

of the rolling angular momentum is p rese rved p r i o r to and immediately

a f t e r dece lera tor device deployment.

F o r the attached dece lera tor t he re was no divergence caused by

T h e r e is a nominal reduction in the ro l l -

The composi te

It should be recognized that the values used f o r the pitch and yaw damp-.

ing fac tor (C

fo r the attached dece lera tor configurations ( s e e I t e m 28 in Tables A- I

through A-XI of Appendix A and Section I of Volume II). paucity of data relating to this fac tor for the configurations under study,

this t e r m was evaluated using Figure 10 i n Section I of Volume I1

( re ferenced to the pa rame te r of qD /v) to account fo r the composi te

capsule/decelerator cg position.

f o r Mach number effect (for the range of Mach numbers of i n t e re s t ,

M*2 to 5).

theory f o r (Cm t C

tions a s shown by Figure 14 in Section I of Volume 11.

t Cm, ) in the dynamic ana lyses m a y be questionable m 9 CY

In view of the

0

The t e r m then was doubled to account

This approach was predicated on the t rend of da ta and

) v e r s u s Mach number f o r conical configura- m. 9 CY

BASIC B A L L U T E PACKAGE INFORMATION FOR SEVEl

JPL TRAJECTORY

NO.

83

37

A1

19

A4

E 1

Dv (FT) (FT)

12.0 23.7

16.0 25.4

18.5 30.7

16.0 23.0

18.5 21.1

12.0 17.5

DV

(CDAlV

(SQ F T )

158.0

281.5

376.0

281.5

376.0

158.0

(CDA)T

(SQ FT)

536

690

96 1

749

692

359

9, (LB/SQ FT)

20.3

112.5

76.5

9.9

26.2

25.4

10.4

DESIGN DRAG LOAD ( L E )

ATTACHME AND RELEI

DEVICE (LE)

15,320

91,700

89,500

9,260

16,600

10,200

7,300

I 13.2

47.7 I 54.8

4.8

10.1

8.8

3.8

B A L L U T E IN STOWED POSITION

STRING FOR B A L L U T E DEPLOYMENT

T lON CANISTER

HEAT SHIELD AND B A L L U T E CANISTER COVER

RADIAL BRIDLE STRAPS (36 REQUIRED). FORWARD ENDS OF BRIDLE STRAPS TERMINATE WITH A F A N PATCH T Y P E CONSTRUCTION T H A T IS ATTACHED TO T H E PERIPHERAL FABRIC

FABRIC T H A T SUPPORTS T H E I BRIDLE STRAP F A N PATCHES

FABRIC T H A T SUPPORTS THE R A D I A L BRIDLE STRAP F A N PATCHES

MARMAN CLAMP WITH 3 EXPLOSIVE B O L T

ASSEMBLIES MARMAN CLAMP WITH

I

3 EXPLOSIVE BOLT ASSEMBLIES

SECTION V - SYSTEM COMPARISONS CER-12842, V O L I

4L CAPSULE DIAMETERS ( D v )

:: 1 AUX:I:RY EQUIPMENT FOR STOWING

12.9

106.1

108.3

5.6

18.6

1 13.3

7.4

B A L L U T E CANISTER AND HEAT SHIELD

(LB)

60

80

110

80

110

60

80

B A L L U T E DACRON FABRIC

(LB)

129.3

1061.0

1083.0

56.1

185.9

132.9

74.3

T O T A L PACKAGE CONCEPT

( L B )

215.4

1294.8

1356.1

146.5

324.6

215.0

165.5

INLET FOR RAM INFLATION (16)

,/" /'

A D l A L r

NOTE: UNLESS OTHERWISE SPECIFIED

1 . THE ATTACHMENT DETAILS SHOWN FOR Dv = 12.0 F T ARE FOR TRAJECTORY 83 ONLY

THE ATTACHMENT DETAILS SHOWN FORDv = 16.0 F T ARE FOR TRAJECTORY 37 ONLY

THE ATTACHMENT DETAILS SHOWN FOR Dv = 18.5 F T ARE FOR TRAJECTORY A1 ONLY

2.

3.

4. THE ATTACHMENT DETAILS ARE BASED ON THE USE OF 7075-T6 ALUMINUM UNDER LOAD A T 350 F WITH THE FOLLOWING VALUES:

Ft Y

Fbr

Fs

= 0.62 X 67,000 = 41,500 LB/SQ IN.

= 0.67 X 94,000 = 63,000 LB/SQ IN.

= 0.74 X 46,000 = 34,000 LB/SQ IN

Y

U

I Figure 23 - Trailing BALLUTE

-5%.

PLACES)

I I t MARMA’N CLAMP WITH 3 EXPLOSIVE BOLT ASSEMBLIES

I ‘-/ ’ \ \

SLEEVES COLLAPSED B Y RAM PRESSURE TO PREVENT EXCESSIVE LEAKAGE

T

/

J P L ‘RAJECTORY

NO.

8 3

37

A1

19

A4

B1

22

DEPLOYMENT(ONEF0REACH

STOWAGE

D” (FTI

12.0

16.0

18.5

16.0

18.5

12.0

16.0

DE (F

22

28

31

27

28

18

24 -

MERIDIAN S-

I SECTION V - S Y S T E M COMPARISONS GER-12842 , VOL I

DESIGN DRAG LOAD (LE)

15,330

90,500

89,400

9,260

14,900

10,200

7,310

-

3

7’ - .9

.O

.7

1

.6

.9

.9 -

ATTACHMENT AND RELEASE

DEVICE (LE)

13.9

56.9

65.6

5.8

10.9

9.2

4.6

BASIC BALLUTE PACKAGE INFORMATION FOR SEVERAL CAPSULE DIAMETERS (Dv)

(CDA)V

(SQ F T )

158.0

281.5

376.0

281.5

376.0

158.0

281.5

RAP)

536

796

1023

750

842

3 59

633

20.3

88.0

68.8

9.9

16.0

25.4

10.4

AUXILIARY BALLUTE BALLUTE

10.1

63.1

68.6

6.2

18.4

11.6

7.7

Fs = 0.74 X 46,000 = 34,000 LEI’S0 IN. h l

60

80

110

80

110

60

80

100.7

631 .O

686.0

61.9

183.5

116.3

77.0

NOTE: UNLESS OTHERWISE S PEClFlED

1 . THE ATTACHMENT DETAILS SHOWN FOR Dv = 12.0 F T ARE FOR TRAJECTORY 83 ONLY

THE ATTACHMENT DETAILS SHOWN FOR D V = 16.0 F T ARE FOR TRAJECTORY 37 ONLY

THE ATTACHMENT DETAILS SHOWN FOR Dv = 18.5 F T ARE FOR TRAJECTORY A1 ONLY

2.

3.

4. THE ATTACHMENT DETAILS ARE BASED ON THE USE OF 7075-T6 ALUMINUM UNDER LOAD A T 350 F WITH T H E FOLLOWING VALUES:

Ft Y

Fbr

= 0.62 X 67,000 = 41,500 LB/SQ IN.

= 0.67 X 94,000 = 63,000 L B / S Q IN. Y

TOTAL PACKAGE CONCEPT

(LE)

184.7

831 .O

930.2

153.9

322.8

197.1

169.3

Figure 2 4 - Attached B A L L U T E

- 54-

JPL TRAJECTORY

NO.

83

37

A 1

19

A4

E1

22

D" (FT)

12.0

16.0

18.5

16.0

18.5

12.0

16.0

(FT)

25.7

30.4

35.9

31.05

31.5

21.3

20.07

f 6 5 -1

1 SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

3ASlC B A L L U T E PACKAGE INFORMATION FOR SEVERAL CAPSULE DIAMETERS (Dv)

,A)V > F T ) - 58.0

31.5

76.0

11.5

76.0

58.0

31.5

536

735

1005

749

800

3 59

633

20.3

103.0

72.15

9.9

17.5

25.4

10.4

DESIGN DRAG LOAD ( L B )

15,400

93,300

90,900

9,260

14,820

10,200

7,310

z--\ FOR D v = 12.0 FT

~

ATTACHMENT AND RELEASE

DEVICE ( L E )

13.4

51 .8

57.7

5.1

9.4

8.9

4.1

AUXILIARY EQUIPMENT

FOR STOWING ( L E )

4.3

35.1

36.3

2.9

6.6

5.9

3.7

B A L L U T E CANISTER AND HEAT SHEILD

(LB)

60

80

110

80

110

60

80

B A L L U T E DACRON FABRIC

( L B )

42.6

351 .O

363.0

29.4

65.6

58.8

36.9

T O T A L PACKAGE CONCEPT

120.3

51 7.9

567.0

117.4

191.6

133.6

124.7

B A L L U T E B A L L U T E FABRIC FABRIC

\ HARMAN CLAMP W I T MARMAN CLAMP WITH

9

NOTE: UNLESS OTHERWISE SPECIFIED

1. T H E ATTACHMENT DETAILS SHOWN FOR Dv = 12.0 FT ARE FOR TRAJECTORY 83 ONLY

2. T H E ATTACHMENT DETAILS SHOWN FOR Dv = 16.0 F T ARE FORTRAJECTORY 37 ONLY

3. T H E ATTACHMENT DETAILS SHOWN FOR Dv = 18.5 F T ARE FOR TRAJECTORY A 1 ONLY

3 EXPLOSIVE B O L T 4SSEMB LIES

TRAP)

3 EXPLOSIVE B O L T ASSEMBLIES

4. T H E ATTACHMENT DETAILS AREBASED ON T H E USE O F 7075-T6 ALUMINUM UNDER LOAD A T 350 F WITH T H E FOLLOWING VALUES:

Ft Y

Fbr

FB

= 0.62 X 67,000 = 41,500 LB/SQ IN.

= 0.67 X 94,000 = 63,000 LB/SQ IN. Y

= 0.74 X 46,000 = 34,000 LB/SQ IN. U

Figure 25 - Tucked-Back BALLUTE

- 56

BASIC ATTACHED 12

J P L rRAJECTORY

NO.

8 3

37

A1

19

A4

61

22

12.0

16.0

18.5

16.0

18.5

12.0

16.0

-

( 5 ISC -

E

E

6

i

E

3

E -

-CAPSULE SECONDARY STRUCTURE SUPPO CANISTER FOR AIRMAT CONE STOWAGE

FABRIC ATTACHMENT SKIRT

AIRMAT CONE IN DEPLOYED POSITION I I”

MARMAN CALMP WITH 3 EXPLOSIVE BOLT ASSEMBLIES

I

SECTION V - S Y S T E M COMPARISONS C E R - 1 2 8 4 2 , VOL I

(LB/SQ FT)

20.3

112.5

75.4

9.9

23.2

22.93

10.4

0-DEG AIRMAT CONE PACKAGE INFORMATION FOR SEVERAL CAPSULE DIAMETERS (Dv)

DESIGN DRAG LOAD (LB)

15,330

91,500

92,100

9,260

14,800

9,740

7,310

36

88

85

149

‘i I

i t s

IE (36)

ATTACHMENT AND RELEASE

DEVICE (LB)

14.4

58.4

67.3

5.9

10.8

9.1

4.7

AUXILIARY EQUIPMENT

FOR STOWING ( L e )

7.2

77.6

42.8

5.4

15.1

5.9

3.9

AIRMAT CONE CANISTER AND HEAT SHIELD

(LB)

60

80

110

80

110

60

80

AIRMAT CONE DACRON FABRIC

(LB)

71.8

776.0

428.0

53.8

151 .O

58.7

39.4

NOTE: UNLESS OTHERWISE SPECIFIED

1 . THE ATTACHMENT DETAILS SHOWN FOR D v = 12.0 FT ARE FOR TRAJECTORY 83 ONLY

2. THE ATTACHMENT DETAILS SHOWN FOR DV = 16.0 FT ARE FOR TRAJECTORY 37 ONLY

3. THE ATTACHMENT DETAILS SHOWN FOR Dv = 18.5 FT ARE FOR TRAJECTORY A1 ONLY

4. THE ATTACHMENT DETAILS ARE BASED ON THE USE OF 7075-T6 ALUMINUM UNDER LOAD A T 350 F WITH THE FOLLOWING VALUES:

Ft Y

Fbr

Fs

= 0.62 X 67,000 = 41,500 LB/SQ IN.

= 0.67 X 94,000 = 63,000 LB/SQ IN. Y

= 0.74 X 46,000 = 34,000 LB/SQ I N U

T O T A L PACKAGE CONCEPT

( L B )

153.4

992.0

648.1

145.1

286.9

133.7

128.0

T R A I L I NG B A L L U T E P I T C H YAW D A M P I N G -0 .29

; ARE I N A C C U R A T E ! I I,P A N D 8

A T T A C H E D B A L L U T E P I T C H YAW D A M P I N G -0 .270

h

m 0

X

I-

c

: 10 LL v

w 0 3 I-

I- 1 U

-

0 50 100

U

,g

- ---p

150 T O T A L A N G L E ( D E G R E E S )

4c

- 30

20

h

m 0 c

X

I- : 1 0 LL v

W 0 3 I-

I- _J

-

4 0

T U C K E D - B A C K B A L L U T E P I T C H YAW D A M P I N G -0.336

40r

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I 8 I I 1 I 1 I i 1 I I I I I I I I

---! j__ 0

ANGULAR R A T E S ( R A D I ANS P E R SECOND)

-0 .6 0 0 . 6

1 I I i N O T E :

ARROW I NO I C A T E S D E P L O Y M E N T A L T 1 T U D E

1

T O T A L A N G L E A N G U L A R R A T E S ( D E G R E E S ) ( R A D I A N S P E R S E C O N D )

h

m 0 c

X

I- W W

LL v

W 0 3 I-

c -I a

-

T O T A L A N G l ( D E G R E E S )

4c

- 3c

2c

h

m 0 c

X

c t: 1 c LL v

W 0 3 I-

I- 1

-

u c

- 0 . 6 ANGULAF ( R A D I A \

A I R M A T CONE

0 .6 1 ! A T E S P E R S E C O N D )

P I T C H YAW D A M P I N G -0 .280

2 4 6 T O T A L ANG ( D E G R E E S )

4c

- 3c

20

h

m 0

x I-

c

: 10 LL v

W 0 3 I-

I- _1

-

u o - [

AN

~, L A R 0 .6 1 .0

l A T E S ( R A D I A N S P E R SECOND)

Figure 27 - Decelera tor Oscillation Charac te r i s t ics (Atmosphere VM8; Tra jec tory 19)

- 59-

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

T R A I L I NG B A L L U T E *

T U C K E D - B A C K B A L L U T E P I T C H YAW D A M P I N G = -0.258

70

60

50 n 0 o 40 r

x t- 30

- 20

W W LL

W 0

E l 0

2 4 6 T O T A L A N G L ( D E G R E E S )

E A N G U L A R R A T E S

A T T A C H E D B A L L U T E P I T C H Y A W D A M P I N G = - 0 . 2 0 8

70 70

60 60

50 50 n 0

n

o 40 0 c

o 40 r

x x k 30 L 30

20 '20 W LL

W W

W 0

W 0

2 1 0 210 - - k 1 I-

-I 4 0 a

0 2 4 6 8 -0.6 0 0.6 1 T O T A L A N G L E A N G U L A R R A T E S

( R A D I A N S P E R S E C O N D ) ( D E G R E E S ) ( R A D I A N S P E R S E C O N D )

70

60

50 n ? 40

x L 30

'20 W lA.

W 0

El0 b- 1 4 0 -0.6 0 0.6

( R A D I A N S P E R S E C O N D )

!

8 . o

N O T E : ARROW I NO I C A T E S D E P L O Y M E N T A L T I T U D E

A I R M A T C O N E

3

P I T C H Y A W D A M P I N G -0.218 70

60

50 h

m 0 40 r

x 30

- 20

W LL

W 0

E l 0 k 1 4 O

0 2 4 6 8 -0.6 0 0.6 1.0 T O T A L A N G L E A N G U L A R R A T E S ( D E G R E E S ) ( R A D I A N S P E R S E C O N D )

-

Figure 28 - Decelerator Oscil lation Charac t e r i s t i c s (Atmosphere VM7; Trajectory 22)

-60 -

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

3 . COMPARISONS O F COMPOSITE SYSTEMS

a . Gene ra l - The final compar ison of the expandable dece le ra to r cha rac t e r i s t i c s

was made p r imar i ly in t e r m s of engineering design considerat ions.

In o ther words s ince a l l the configurations init ially w e r e "s ized" to

a t ta in specified t a rge t Mach number/alt i tude conditions ( s e e Appen-

dix B ) , the compar ison was made on the bas i s of the 17 cha rac t e r -

i s t i c s Table IV shows the r e su l t s of this compar ison .

Dacron was used f o r the envelope fabr ic of all the dece le ra to r s . The

r e su l t s fo r the var ious charac te r i s t ics in Table I V a r e d i scussed below.

inTab le IV.

- b. I tems 1 and 2 - Decelerator Diameter and Altitude a t Mach Number 1

The dece le ra to r diameter was de te rmined by the f i r s t approximation

analysis procedure descr ibed in Section V of Volume I1 and i l lus-

t ra ted in F igure 1 0 of t h i s volume.

e r a t o r s i z e w e r e selected as corresponding with o r tending toward

the minimum weight fraction fo r the dece le ra to r device that would

achieve a ta rge t point Mach number of about one n e a r a t a rge t a l t i -

tude of 20, 000 f t for the A l , B3 and 1 9 en t ry cases and a t a rge t a l t i -

tude near 30, 000 ft fo r the 2 2 en t ry case . The values w e r e obtained

f r o m Figures 6 7 , 68, 69 , 7 0 , 73 , 74 , 87 and 88 insec t ion VIof Vol-

ume 11.

tor ies a r e the identical designs f o r the 2 2 and 19 t r a j ec to r i e s , r e -

spect ively.

var ia t ion on s y s t e m per formance and engineering design cons idera-

t ions.

The numer ica l values of decel-

Note that the dece lera tor s i zes f o r the 23 and 30 t r a j ec -

The purpose was to a s s e s s the effect of a tmosphere

Also note that the dece lera tor s i z e s es tabl ished on the bas i s of the

f i r s t approximation analysis procedure was reasonably accu ra t e for

the A1 and B3 ent ry cases to achieve a t a rge t Machnumber ofabout

one n e a r 20,000 ft .

F o r the 19 t r a j ec to ry with a t a rge t alt i tude near 2 0 , 000 ft and 2 2

-61-

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

- 6 2 -

a b ;

N - w d - 0 . . . . .n i i . o o h P 0 - 0 . . . . . - * : o ; E m 2 0 - 2 : . . . .

- . . - Q Q

A N ,

. . . . . . Y) C I Q P C - . . Z o e - . a m o o _ . . _ . . m i 3 . . . . . . . C

a - . n : % K O ; 0 ; g o N $ ?

m . . . . . C N c a .n- . o o a - . C d m m . . . . . . e.&: d e N - y o ; , 2 ; 6 ; -4: . . . . . . , 2 . ;

1 1 1 I 1 I I 1 1 I I 1 1 I 8 I I I I

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

t r a j ec to rywi th a ta rge t a l t i tude of 3 0 , 000 f t , the procedure was con-

serva t ive . Consequently i t can be expected that sl ightly s m a l l e r dece l -

e r a t o r s i zes could be employed to achieve the specified t a rge t con-

ditions fo r these en t ry cases with a s m a l l amount ofweight saving.

- c . I tems 3 and 4 - Decelera tor Weight and Envelope Weight

As d iscussed insec t ion 111, I tem 1 useful integrated t radeoffs can be

made between dece lera tor and total weight in t e r m s of Mach number

and al t i tude a t deployment, dece le ra to r s i ze , per formance effective-

ness , a n d m a t e r i a l cha rac t e r i s t i c s . The formulat ion of the t radeoffs

for the specif ic dece le ra to r s is es tab l i shed in AppendixA of Volume 11.

Note that the weight/strength ana lys i s of Appendix A, Volume I1

a s s u m e s that the dece lera tor m a t e r i a l s w e r e operating a t a s t a t i c

elevated design t empera tu re . In the c a s e of dacron this t empera -

t u re leve l was taken a s 350 F where the s t rength is nominally one

half the value compared to room t e m p e r a t u r e o r about 70 F.

t ionally, a des ign safety fac tor of 2. 0 i s ref lected in the weight/

s t rength ana lys i s .

ing t empera tu re i s considered as a p rac t i ca l design point for in-

f la table s t r u c t u r e s fabr icated of flexible m a t e r i a l s .

Addi-

A half- s t rength operat ing leve l with cor respond-

On the bas i s of the above considerat ions, a f i r s t approximation

weight was es tab l i shedfor the dece le ra to r s i z e s corresponding with

I tem 1 of Table IV (see I t em 6 of Tables A - I through A-XI in Ap-

pendix A). Using these va lues , the proport ion of weight a l located

to the dece le ra to r envelope was de te rmined . Then using the the r -

mal ana lys i s procedures of Section IV of Volume 11, a second ap -

proximation was made to s e c u r e a m o r e l ikely value fo r the opera-

ting t e m p e r a t u r e (Item 5) and unit weight of the dece le ra to r enve-

lope (I tem 4).

through 50 of Volume I1 and I tem 9 of Tables A - I through A-XI of

Appendix A.

includes a unit coating weight of a t l ea s t 0. 01 lb/sq ft to provide a

The values de te rmined a r e shown in F igu res 46

Note that for all c a s e s the dece le ra to r envelope weight

- 6 3 -

low value of poros i ty for the envelope . t e rna l p re s su r i zed gas leakage to no g r e a t e r than 0. 02 lb/sq f t /sec.

The coating l imi t s the in-

In re i te ra t ion the s t rength and the re fo re the weight of the mer id ian

cables f o r a l l the dece le ra to r s and the r i s e r l ine of the t ra i l ing

BALLUTE is based on the half s t rength of dac ron m a t e r i a l with a

design safety fac tor of 2 . 0. The weights fo r I tem 3 in this Table

a r e based on the above considerat ions.

- d. I tems 5 and 6 - Design and Actual Maximum Dece le ra to r Envelope Tempera tu re

In comparing I tems 5 and 6 , note that the second approximation fo r

the a s sumed operat ing t empera tu re f o r the dac ron dece le ra to r en-

velope was quite a c c u r a t e f o r the A1 and 19 t r a j ec to r i e s and for the

AIRMAT cone in the 2 2 t r a j ec to ry .

second approximation was s t i l l conserva t ive by as much as a f ac to r

of 1 . 5 to 2 . 5. However as noted above ( s e e Item 4) the d e c e l e r a t o r

unit weight includes a minimum coating of a t least 0 . 01 lb/sq f t .

F o r the o the r t r a j e c t o r i e s the

Thus with the possible exception of the a t tached BALLUTE fo r the

B3 t ra jec tory w h e r e a 10 percent saving in dece le ra to r weight might

be real ized, only nominal weight would be saved for the o ther c a s e s .

A l so as noted above the m e r i d i a n cable and r i s e r - l i n e s t r eng th and

weight would co r re spond approximate ly to a n operat ing t e m p e r a t u r e

of 350 F with a design safety fac tor of 2 . Consider ing the 19 and 30

t r a j ec to r i e s ,where the operat ing t e m p e r a t u r e is equivalent to r o o m

t empera tu re , the dece le ra to r m e r i d i a n cables and r i s e r s ac tua l ly

would have a design safe ty fac tor of about 4 based on the weights of

I tem 3 .

and 23 t r a j ec to r i e s would range between about 3 . 2 and 3 . 8 f o r the

indicated va lues of operat ing t e m p e r a t u r e .

The design safe ty f ac to r s cor responding with the B3 , 22

- e . I tem 7 - Auxil iary Gas Inflation S y s t e m Weight

F o r the r a m - a i r inflated d e c e l e r a t o r s , th i s i t e m m a y be cons idered

I I I 1 I 1 1 1 I 1 I 1 1 I I I I

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I -,

SECTION V - SYSTEM COMPARISONS GER-12842, VOL I

as optional. By the definition of this study, however, i t is manda-

to ry with the 120-deg AIRMAT cone.

flation aid gas f o r the r a m - a i r inflated configurations was approxi-

mated as 50 percent of that required for the fully inflated decel-

e r a t o r a t the design initial deployment Mach number , a l t i tude, and

in t e rna l p r e s s u r e corresponding to the p r e s s u r e recovery a t the

ram-air inlets of the decelerator .

factor of 1. 5 to account f o r the container weight ( s e e I tem 12 of

Table A - I through A-XI i n Appendix A ) . F o r the AIRMAT cone the

inflation gas and container weight was determined f r o m Figure 100

in Section VI1 of Volume I1 corresponding to the s i z e and supporting

p r e s s u r e requi rements encountered a t the init ial deployment Mach

number and altitude for this configuration.

The weight of auxi l iary in-

This value was multiplied by a

- f . I tems 8 , 9 and 10 - Ancillary Equipment Weight, Attachment Design Safety Factor ,and Packaging Volume

I tem 8 includes the weight es t imates for the dece lera tor attach-

men t s , packaging equipment, separat ion and deployment means ,

and base heat shield.

ment and separat ion means a r e provided fo r each of the dece le ra to r s

considered in this study.

Figures 23 through 26 i l l u s t r a t e how at tach-

Note that the anci l lary equipment weight includes the capsule b a s e

heat shield to protect the dece lera tor and equipment f r o m the b a s e

heating encountered during en t ry . The shield probably will be fab-

r icated of f iberglass with a thickness capable of maintaining the

in t e rna l t empera tu re below 200 F for a total heat input load of

about 1000 B T U ' s / s q f t . On the bas i s of M a r s en t ry energy levels

and typical base heating levels encountered in orb i ta l e n t r y of blunt

body shapes , this heat input is considered r ea l i s t i c . The weight

of the heat shield allows fo r additional reinforcing to support the

base p r e s s u r e and deceleration loads of en t ry .

function of the heat shield would be utilized to ex t r ac t and deploy

the dece lera tor .

The separa t ion

-65-

SECTION V - SYSTEM COMPARISONS GER-l2842A, VOL I

I t em 9 indicates the a t tachment design fac tor .

spond with the load developed a t full inflation of the d e c e l e r a t o r s

and the design yield s t r e s s f o r the attachment components a r e in-

dicated in F igu res 23 through 26.

conservat ively designed by assuming operat ion a t a n elevated t em-

pe ra tu re of 350 F and the m a t e r i a l s t r e s s capabili ty cor responding

to this t empera tu re level was used.

The values c o r r e -

The attachment suppor ts a r e

The packaging volume indicated by I t em 10 f o r the d e c e l e r a t o r s is

referenced to a packaging densi ty of 30 lb/cu f t , which is a typical

value for expandable dece le ra to r s fabr ica ted of flexible m a t e r i a l .

Even i f the packaging densi ty w e r e reduced to 20 lb/cu f t , the vol-

ume requi rements a r e not excess ive in t e r m s of the volume ava i la

bil i ty provided i n this study.

g. I t em 11 - Composite Sys tem Velocity a t 5, 000 f t .above T e r r a i n

The tabulated data for this i t e m and the space - t ime h is tor ies of

F igu res B-1 through B-6 in Appendix B show that reasonably low

subsonic velocit ies will be attained s o that conventional parachute

s y s t e m s could be deployed to l imit t e r r a i n impact veloci t ies to

acceptable leve ls .

1 established on the bas i s of achieving a t a rge t point Mach number

of about one n e a r o r above a n alt i tude of 20,000 ft in the VM8 a tmo-

s p h e r e and 3 0 , 0 0 0 ft in the VM7 a tmosphere .

This finding is f o r the dece le ra to r s i z e s of I t em

- h. I tem 12 - Composite Sys tem Fl ight -Pa th Angle a t 5, 000 ft above T e r r a i n

The attached expandable dece le ra to r s can def lec t the e n t r y capsule

flight-path fo r the A I , 19, 2 2 , 23 and 30 e n t r y c a s e s to within 10

deg of the ver t ica l at a n al t i tude of 5000 f t .

be compatible with the levels of subsonic veloci t ies of I t em 11 and

the energy and control capabili t ies of a sof t - landing, t e rmina l -

s t age , r e t rosys t em of the Surveyor type.

This def lect ion would

-66- Revised 21 October 1966

SECTION V - SYSTEM COMPARISONS G E R - 12842A, VOL I

- i. Item 13 and 14 - OscillationAmplitudes a n d R a t e s a t 5000-ftAltitude

AS descr ibed previously, for the case of the t ra i l ing dece le ra to r s

there is a divergence tendency in angle of a t tack resul t ing p r imar i ly

f r o m the inadequate descr ipt ion of the 8-degree-of - f reedom com-

puter formulat ion ( see F igures 27 and 28 and Appendix C.) Limited

experience with the application of t ra i l ing dece lera tors attached to

a spinning forebody generally has not exhibited this tendency, a t

l ea s t to the magnitude encountered in this study.

the analytical (mathematical) descr ipt ion of the s y s t e m dynamics

should be studied and evaluated in much g r e a t e r detai l in future pro-

g r a m s fo r the application of t ra i l ing dece le ra to r s .

motion involving the use of the attached dece le ra to r s did not resu l t

in a l a rge angular divergence.

discussion of the dynamic analysis considerations and resu l t s .

Comparing the magnitudes of oscil lation amplitude and r a t e for the

corresponding decelerator configurations, the effect of a tmosphe r i c

density is apparent . The reduced damping moments in all modes of

oscil lation f o r t ra jectory 22 r e su l t - in l a r g e r values of angular am-

plitude and r a t e .

dicates that the attached configurations provide be t te r stabil i ty than

the t ra i l ing decelerator f o r the reason previously discussed.

bes t of the attached configurations is the tucked-back BALLUTE;

p r imar i ly because of higher and m o r e favorable values fo r C

X /Dv and (Cm t Cm.). See I tems 26, 27, and 28 in Tables

A-I11 and A-XI in Appendix A.

It is apparent that

The s y s t e m

See Appendix C f o r a comprehensive

The compar ison of the sepa ra t e dece le ra to r s in-

The

, Nci!

9 cy CP

I tem 15 - Maximum Operating g-Level

The decelerat ion g-levels encountered a t full inflation of the decel-

e r a t o r s a r e not excessive in re la t ion to those in ea r th en t ry ap-

plications.

than the peak loads a t launch and boost in the entry of the basic

capsule fo r the t ra jec tor ies s tudies .

Except for t r a j ec to ry A l , the load levels would be l e s s

Revised 21 October 1966 -67-

SECTION V - SYSTEM COMPARISONS GER- 12842A, VOL I .*

k. -

-68-

As i n Item 1, the dece le ra to r s fo r t r a j ec to r i e s 23 and 30 a r e the

same designs for t r a j ec to r i e s 2 2 and 19, respect ively. The c o r -

responding g-loads at full inflation of the dece le ra to r s for t r a j ec -

t o r i e s 23 and 30 a r e 2 and 1. 5 t imes g r e a t e r than the 2 2 and 19

c a s e s . Refering back to I t em 9 (Attachment Design) , the at tach-

men t design f o r both configurations in t r a j ec to ry 23 and f o r the

tucked-back BALLUTE in t r a j ec to ry 30 would not be adequate . Some

s t ruc tu ra l strengthening of the at tachments would be r equ i r ed with

nominal i n c r e a s e in the dece le ra to r a t tachment weight.

however, that the a t tachment design is conservat ive on the bas i s of

the a s sumed elevated operat ing t empera tu re .

the effects of the s y s t e m dynamics on the dece le ra to r s t r eng th and

weight.

I tems 16 and 17 - Total Dece le ra to r Sys t em Weight and Weight F rac t ion -

I tem 16 is the s u m of I t ems 3 , 7, and 8 and I tem 17 is the percent -

a g e of the total dece le ra to r weight to the total en t ry capsule weight.

The tucked-back BALLUTE has the m o r e favorable weight f rac t ion

by a slight m a r g i n ove r the AIRMAT cone, which is the next bes t

configuration.

among al l configurations does not exceed two pe rcen t of the total

en t ry capsule weight, much l e s s than the a c c u r a c y of the a s s u m p -

tions and approximations made in the p a r a m e t r i c ana lyses of this

s tudy .

Recal l ,

Appendix C cons iders

F o r t r a j ec to r i e s 19 and 2 2 the weight difference

F a c t o r s other than weight and pe r fo rmance wi l l be impor tan t i n

choosing the m o s t sui table expandable t e r m i n a l d e c e l e r a t o r fo r a

M a r s lander sys t em. These f a c t o r s would include s t a t i c and dy-

namic aerodynamic s tabi l i ty , complexi ty and cos t of fabr icat ion

methods, sequencing and cont ro l functions, i n t e r f ace cons t ra in ts ,

e t c .

a m o r e comprehensive and detai led s y s t e m des ign than encom-

passed by this s tudy ( s e e next sec t ion) .

The accu ra t e evaluation of t hese f a c t o r s only can be m a d e by

Revised 2 1 October 1966

1 ‘ 1 -. 1 8 I 1 I I 1 1 I I 1 I I I 1 I D

GER-12842. VOL I

SECTION V I - RECOMMENDATIONS

As in fe r r ed f r o m the s ta tement of work fo r this p r o g r a m , this study was

not expected to yield data in sufficient detai l f o r complete and final engineer-

ing designs of expandable dece lera tors for M a r s a tmosphe re entry. Conse-

quently recommendat ions w e r e made f o r a r e a s requir ing additional investi-

gation and analyses . Additionally descr ipt ions of development, simulation,

and proof- t e s t p rocedures to qualify aerodynamic dece lera tor s y s t e m s for

the M a r s miss ion , including the types of fac i l i t i es required, w e r e made

( see Sections VIII, IX, and X of Volume 11).

The a r e a s recommended a s requiring additional investigation include:

1. Detailed configuration design analyses fo r a n at tached

expandable decelerator assoc ia ted with a specific en t ry

capsule and per formance envelope within the broad

l imits encompassed by this study

2. Fabricat ion techniques and constraints for a n approxi-

mate ly full- sca l e , ram-a i r - inf la ted attached expandable

configuration

3 . Conventional wind-tunnel and free-f l ight wind- tunnel

model t e s t s to determine the aerodynamic pe r fo rmance

and stabil i ty of an en t ry capsule/attached expandable

configuration under s imulated operating environments

( see Section VIII of Volume 11)

4. Design and fabrication of a full- o r near - fu l l - sca le

functional mockup of a n en t ry capsule/attached expand-

able configuration for packaging, deployment, and in-

flation t e s t s in the NASA Ames o r Langley fu l l - sca le ,

wind- tunnel facil i t ies

-69-

5. Large-sca le , f ree- f l igh t s imulat ion t e s t s of a n en t ry

v e hic 1 e /a tt a c he d expandable c onf igu r a t i on us i ng r o c ke t

boost techniques

Section IX of Volume 11)

as i l lus t ra ted by F igu re 2 9 ( s e e

6. Functional, environmental , s te r i l i za t ion and rel iabi l i ty

tes ts of m a t e r i a l s hardware , and anc i l l a ry equipment

assoc ia ted with the en t ry capsule/attached expandable

c onf igu r a t i on

1 1 8 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I

GER-12842 , VOL I SECTION VI - RECOMMENDATIONS

/ DE-SPIN J E T S q, 1S0,OOO FT

a'/; M A C H 5.0 A D D P E P DRAG BRAKES OR

A D D P E P R E T R O ROCKETS \ / Q C O N E D E P L O Y E D

NOSE C O N E O F F

C-BAND TRANSPONDER 225-MC T R A N S M I T T E R

SPIN R A T E 3000 LB MAX

V E H I C L E

C O N D OR T H I R D AGE D E P E N D I N G

N F I G U R A T I O N

L A U N C H

B E A C O N T R A N S P O N D E R ON F IRST S T A G E IGNIT ION T R A C K I N G F L A R E S T E L E M E T R Y ON S E Q U E N C E R O N

S T A T I C PRESSURE D Y N A M I C PRESSURE DE c E LE RAT OR SHOCK D E C E L E R A T O R DRAG A C C E L E R A T I O N T E MPE R A T URES B A L L U T E I N T E R N A L PRESSURE F M / F M P A M E V E N T MONITORING

I N - F L I G H T ( E L E C T R O M E C H A N I C A L T IMER) - AI

L A S T STAGE BOOSTER I G N I T I O N L A S T S T A G E BOOSTER SEPARATION, D R A l T E L E M E T R Y C A L I B R A T E

DE-SPIN JETS ( R A T E GYRO) ON-BOARD CAMERAS (2) S T A T I C A N D DYNAMIC PRESSURE PORTS C C A N I S T E R E J E C T I O N

D A T A TRANSMISSION - A D D P E P T E L E M E T R Y

SECTION VI - RECOMMENDATIONS GER-12842, VOL I

) D P E P PROGRAMMING

; BRAKES

P E N

D E C E L E R AT I ON C A N I S T E R 0 F F ’, B A L L U T E D E P L O Y E D

\ D E P LOY E D

WATER OR L A N D I M P A C T

PARA B A L L U T E F L O T A T I O N 240-MC B E A C O N FLASHING L I G H T D Y E MARKER 37-KC MARKER

F i g u r e 2 9 - Rocket Boost Technique for Simulation Tes t

- 72+

GER-12842, VOL I

SECTION VI1 - CONCLUSIONS

The r e s e a r c h conducted during this study has led to the following conclusions:

1. The suitable application of expandable t e rmina l decel-

e r a t o r s f o r M a r s a tmosphere en t ry can be establ ished

by the analyt ical formulation of environmental fac tors

and effects governing engineering applications and

s t ra ight forward engineering techniques of analysis and

design.

2 . Definitive t rends toward minimum weight f ract ions (of

reasonable magnitude) for expandable t e rmina l decel-

e r a t o r s with corresponding optimum values for init ial

operating Mach number (that i s , dynamic p r e s s u r e ) to

aerodynamical ly re ta rd en t ry capsules to Mach num-

b e r s of less than 1 . 0 a t alt i tudes of 2 0 , 0 0 0 and 30,000 ft

above M a r s for specific model a tmosphe res has been

establ ished. F o r all the en t ry c a s e s considered in this

study, the suitable applications fo r expandable t e rmina l

dece le ra to r s fo r Mars a tmosphe re e n t r y a r e within the

cu r ren t de c e 1 e r a t or techno logy.

3 . Dacron and Nomex, which a r e compatible with plane-

t a r y s te r i l i za t ion requirements , can be employed safely

for fabr icat ion of expandable t e rmina l dece le ra to r s

under the combined aerodynamic and t h e r m a l loading

environments encountered in M a r s en t ry for the t r a j ec -

to r ies considered in the study. F o r all c a s e s analyzed

minimum coating thickness of the o r d e r of 0. 01 lb/sq ft

can be employed to maintain low acceptable values of

- 7 3 -

SECTION VI1 - CONCLUSIONS GER-l2842A, VOL I

porosity f o r the dece lera tor envelope and to maintain

the ma te r i a l t empera ture to acceptable design values

with only minimum weight penalt ies.

4. The effect of varying t a rge t point Mach number f r o m

a nominal value of 1. 0 a t a specified t a rge t altitude has

a measurable effect on dece lera tor s i z e and weight

fraction.

5. Detailed engineering analysis , design, and simulation

testing pointed toward a specific expandable dece lera tor

configuration and performance envelope within the broad

range of values and t rends encompassed by this study

can be undertaken confidently.

implemented over a reasonable period of 24 months f r o m

go-ahead and r e s u l t in a prototype expandable decel-

e r a to r sys t em that could be flight-qualified subsequently

f o r a s e a r l y as the 1973 M a r s lander miss ion ( s e e

Section X of Volume 11).

estimated ( s e e Appendix D) that a p r o g r a m f o r the de-

sign, development, and t e s t of a n expandable te rmina l

aerodynamic dece lera tor fo r a M a r s lander capsule

could be accomplished a t an overa l l cost to the govern-

ment of l e s s than $ 3 million.

Such a p r o g r a m could be

F o r budgetary purposes i t was

- 74- Revised 2 1 October 1966

GER-12842, VOL J

LIST O F REFERENCES

1.

2.

3 .

4.

5.

6 .

7 .

8.

9.

AEDC TR-65-218: Drag Charac te r i s t ics of T h r e e BALLUTE Decel- e r a t o r s in the Wake of the ALARR Payload a t Mach Numbers 2 to 4. Arnold A i r F o r c e Station, Tenn. Arnold Engineering Development Center . 1965.

AEDC TDR-63- 11 9: Pe r fo rmance of Flexible Aerodynamic Dece le ra to r s at Mach Numbers f r o m 1. 5 to 6. Arnold A i r Station, Tenn. Arnold Engineering Development Center . 1963.

Alexander , W. C. : Investigation to Determine the Feasibi l i ty of Using Inflatable Balloon Type Drag Devices f o r Recovery Applications i n the Transonic , Supersonic , and Hypersonic Fl ight Regime. Part 11. Mach 4 to Mach 10 Feasibi l i ty Investigation. Akron, 0hio.Goodyear A i r c r a f t Corp. ASD TDR-62-702. December 1965.

Charczenko, N. : Aerodynamic Charac t e r i s t i c s of Towed Spheres , Coni- c a l Rings and Cones Used as Dece le ra to r s at Mach Numbers f r o m 1. 57 to 4 .65. TN D-1789. NASA, Apr i l 1963.

Charczenko. N. : and McShera. J. T. : Aerodvnamic Charac t e r i s t i c s of Towed Cones Used as Decelera tors a t Mach Numbers f r o m 1 . 5 7 to 4 .65. TN D-994. NASA, December 1965.

Altgelt , R. : Gemini BALLUTE Sys tem Development. GER- 11538 Akron, Ohio. Goodyear Aerospace Corporat ion. January 1965.

GER- 11665: Aerodynamic Deployable Dece le ra to r Pe r fo rmance Evalua- tion P r o g r a m . Akron, Ohio. Goodyear Aerospace Corporat ion.

AEDC-TR-65-266: The Charac te r i s t i c s of a BALLUTE in the Wake of the Mar t in Ful l sca le SV-5D Vehicle a t Mach Numbers from 0 . 6 to 2. 9. Arnold A i r Station, Tenn. Arnold Engineering Development Center . 1965.

AEDC-TR-64- 13 1: Gemini BALLUTE S t ruc tu ra l T e s t a t Mach Numbers 0. 55 and 1. 92. Arnold A i r Station, Tenn. Arnold Engineering De- velopment Center . 1964.

-75-

GER- 12842, VOL 1 LIST O F REFERENCES

10. McShera, J. T. : Aerodynamic Drag and Stability Charac te r i s t ics of Towed Inflatable Dece lera tors a t Supersonic Speeds. TN D- 1601. NASA.

11. GER- 11762: BALLUTE Evaluation P r o g r a m f o r P ro jec t Sleigh Ride. Akron, Ohio. Goodyear Aerospace Corporat ion.

- 76-

GER-12842, VOL I

APPENDIX A - DECELERATOR CHARACTERISTICS

A n explanation of each i t e m in Tables A - I through A-XI is given below. Each

number in the l i s t cor responds with each i t e m number in the tab les .

1.

2 .

3 .

4.

5.

6 .

Optimum init ial operating Mach number a t ful l -drag

effectiveness - Defined as the Mach number se lec ted

o r corresponding with the value fo r o r t rend toward

the minimum weight f rac t ion of the dece lera tor that

will achieve the target point Mach number/altitude

conditions.

u r e s 6 7 through 99 in Section VI of Volume 11.

s e e Appendix A of Volume 11.

Dynamic p r e s s u r e a t init ial Mach number - Value

obtained f r o m point-mass t ra jec tory computations

corresponding with the Mach number of I t em 1 above

Altitude a t ini t ia l Mach number - Value secu red f r o m

point- m a s s t ra jec tory computations c o r responding to

I t em 1 above

Adiabatic wal l t empera tu re a t init ial Mach number -

Value corresponding with I tem 1 fo r t empera tu re r e -

covery fac tor of 0 . 9 ( s ee Section I1 of Volume 11)

Drag a r e a a t initial Mach number (C A) - Value based

on d rag a r e a determined as requi red to achieve the

t a rge t Mach nurnber/altitude conditions (obtained f r o m

F igures 52 through 6 2 i n Section V of Volume 11)

Diameter - Value based on dece le ra to r drag coefficient

corresponding to Item 1 ( s e e Section V and VI, Vol-

ume 11) and I t em 5 above

This Mach number is obtained f r o m F i g -

Also

D

- 7 7 -

APPENDIX A GER- 12842A, VOL I

7. Drag coefficient, CD (total) - See I tem 6 above (a l so ,

Figure 8)

8 . Decelerator weight - Value based on weight f ract ion

corresponding to I tem 1 multiplied by the en t ry capsule

weight associated with the specific en t ry case ( s e e

Appendix A of Volume 11)

9 . Minimum prac t i ca l dece lera tor envelope unit weight

f o r combined the rma l and aerodynamic loading envi-

ronment including porosity coating weight of 0. 01 lb/-

sq f t - Value taken f rom Figures 8 9 through 99 by the

analysis descr ibed in Section IV of Volume I1

10. Total dece lera tor sur face a r e a - Value taken f r o m

Figure A-9 by the analysis descr ibed in Appendix A of

Volume I1

11. Total dece lera tor weight (based on I tem 9 ) - I t em 8 x + I tem 9 X I tem 10; for

pendix A of Volume 11)

1 2 . Auxiliary gas inflation aid weight - Defined as 1 . 5 X

(50 percent of I tem 2 9 ) g fo r Trai l ing BALLUTE (TB) , e Attached BALLUTE (AB), and Tucked-Back BALLUTE

(TBB) configurations; fo r the AIRMAT cone (AC) con-

figuration s e e F igure 100 of Section VII, Volume I1

13. Packaging volume required - Based on I tem 11 fo r

packing densit ies indicated. The weights given a r e

the maximum weights of the dece le ra to r s f r o m I tem 11

Inflated dece lera tor volume - Taken f r o m Figure A- 9 by analysis descr ibed in Appendix A of Volume I1

14.

15. Specified inflation t ime ( f rom s t a r t of deployment) -

- 7 8 - Revised 21 October 1966

APPENDIX A G E R -12842A, VOL I

Specified on bas is of s i z e , min imum des i r ed t ime to

full-inflation, reduction of fabr ic f lut ter , and reduced

loads

16.

17.

18.

19.

20.

21.

22.

23.

Mach number a t deployment init iation - Taken f r o m

point-mass t ra jec tory computations as the value occur-

r ing 1. 5 s e c before I tem 1

Dynamic p r e s s u r e a t deployment - Obtained in the s a m e

manner as I tem 16 above

Adiabatic wall t empera ture a t deployment - Corresponds

with I tem 16 f o r t empera ture recovery fac tor of 0 . 9

Centroid of inflated volume - Derived f r o m Figure A-9

by the analysis in Appendix A , Volume I1

T r a n s v e r s e radius of gyrat ion of dece le ra to r squared -

Obtained in the same manner as I tem 1 9

T r a n s v e r s e radius of gyration of composite sys tem

squared -

I tem 11 Item 2 0 ) t g >

(Item 25 - 0 . 253 '} J Rotational radius of gyration of dece lera tor squared -

Obtained in s a m e manner as I tem 19

Rotational radius of gyrat ion of composi te s y s t e m

squared -

r 1

Revised 2 1 October 1966 -79 -

APPENDIX A GER-12842, VOL I

2 4.

25.

26.

27.

28.

29.

30.

Centroid of dece lera tor weight ( f r o m capsule base) -

Derived i n s a m e manner as I tem 19

Composite sys t em cg position -

3 = 0 . 2 5 t- wD[o. 385 t I tem 24 wT

Composite s y s t e m cp position - Approximated as

Item 19 t 0 . 8 6 5 fo r attached configurations only

Estimated C

(per deg ree )

Est imated Cm t Cm, Approximated f r o m Figure

10 of Section I, Volume I1 and doubled to account for

Mach number effect. See F igure 14 of Section I of

Volume I1 (pe r radian about composite s y s t e m cg)

- Approximated f r o m Munk's theory NcY

L s Added mass of inflation g a s (approximate) - Approxi-

mated a s

p, X (Item 14) I

gmRmTm

Defining PT = 2. 7 5 X f [(M), (P,/Pm) 1 ; s e e Section I1

of Volume 11, Figures 22, 23 and 24

Apparent mass effect of boundary layer -

a where 8 A 0 . 03 DD

a Hoerner , S. : Fluid Dynamic Drag . Publ ished by the author . New York, N . Y . 1958.

-80-

m U

m k aJ

U rd

rd c U

a,

U

2

.+ Y

.c

Y

d

.+

c

M

U a, n

In N a

r- 0 c"

a,

3

m m o 0 0 0 0 3

* N . m a 0 + 0 9 N

- c o o 0 0 , o o ln .o . o o o r n o m e

d t - m r- r- co . o m . r - m m - r - o m 0 m m

+ ; \ O N c o m m o m e

m a 9 0 o o ~ o o m . o . O d o d r o d r +

d k

k a, P

5 " r u

E

2 3

.3 * .+

.+ Y

rd

c

d aJ

-0 I * .3 4 2 3

4

V w

k aJ P

5 c c v

E

5 ld .+ Y .+

.3

Y ld d a, k rd M d k n

A 4

4 2

Y v

rd 0

n V

c a,

U '3 rr a, 0 U

M d

CI

.+

.+

6

c a aJ m rd n 2 M .+

$ k 0

d a,

a, V

Y

3

B

h 0 m rr)

d e 0 k U

Y

: E k U

d

APPENDIX A GER- 12842, VOL 1,.

c

a a, m d

c M

n Y

.3

i 2 rd G 0

d .r( * 4 % .- c

l a, a

W 0

k d

c )

c )

m

E - - '3

E .r( c )

c 0

d

c v *

-r( c )

4 '3

.r(

; h a2 m a

C

d

C

c a,

.,- c )

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c )

Ex 0 a a, 21

d k a, P

7 c L:

4

*

E

0

3

E 7 0 > V a,

d

c

0

4

4 2

4 '3

.+ '3

2

5 h 42

V

h 0 d a,

a, u o a 0

G 0

d k x M

0

m 7

*

4

w

.r( Y

'3

s 2

:: a, m k

H m

a, e

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m 0 a M u

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E

c .3 * .3

m 0 a a u

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m Y .3

0 a E V

A

a, a, k -

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h a, 2 ; -5

a x - d .3 - m *

V II

a, M

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m w

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Q) Q) m

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h

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2 5 4

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tn

I3

d w I3

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z

2

n

d C L

I

c c I

U

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4 4

2 .!! L I *

0. co ln 9 . m 9

N - N I n I n N - 4 0.4 . 0 . m O W N . G * -+ .+

5 5 d d H b

'n V - k aJ n E 3 c i: u

2 4

d

c

Id d aJ h Id M d k

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.+ *

n

u v)

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a aJ rn

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U

C

k 0 *

; d

N 4

In

u . d k k a J

4

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6 a J 2 - 3

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I ’ APPENDIX A GER-12842, VOL I

“. . + \ r - 2

- + - L o r -

m e 0 ln m r -

m N O W N a 9 N .-I m m

+ . N . + m A N N 4 0 9 r- .+ m 0 0 - 0 I 0 0

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W m In m m a . m co 0 m N N N . 9 9 N .-I a . . m m 4 m a . 0 m . . d f m m . 0 r - I 4 - 4 Q 9 m . . o o . r - - N m . . . . 4 3 . G 4 r - M N N d V I t- N - 4 m o . 0 0 a 0

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+

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S P J J

k 0 *

a, d

A

a, a, k M a, G

a a, m d P

c M

Y

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c

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3 ‘3

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I a, a

a, U a, a w 0

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0

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a, m k

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0

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V - a a,

d c

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a t s . d

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m r-

c o o 4

k

m i

cc N

> c

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rd

h rd M rd

c

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0- m Y

..-4

k a, U 4-2

a Id c. u

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m m o m N C O

N m m I r - m o N O

m . o m . m . 4 m * - . 4 4

P P J J

rd 0 c)

k.

1 APPENDIX A GER-12842, VOL I,

r- m e

0 9 0

- o m . . o m N d

r- s m o m P

d N m 0 O , . .

N

m m

m N

m 4

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N

m r - m - C O N - 0

o o c l o . . . .

m 0 ,-4

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9 r - N I n 4

0 0 . .

h

m E Y H

c 0 -0 a, m d D Y

2

3

M a, .+

h 0 d *

2 2 a d a , & u u

4

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a a, (0

d P

2 M .+

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rd

c

-3 * 4 w .+

x r n

4 %

0

rd

d

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.+ * .+

.+ Y

5 E x 0 a a, V

d h a,

+

*

n E 2 c u

3

3 0 > V a,

rd

C

0

4

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2 h * c U

w d 0 %

c .r( Y .+ m 0 R M u

€ * m x m a,

rn * .r(

0 R

0 E U

k?

EV

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U +

u - V a, *

Y m w

N 4

4

9 x a

a

.+

2 w 0 M C C d M u P

d

C

,+

.+

*

m Y

E" E u al a, a

E

< Y .r.

d a,

0 C 0

d C d a

w

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d

3 &

2 *

a { A

a '3 -

A

M e, a 0 N 4 - al E

u s 9 I

U 4

r- 0 c o * ln o m . *

. m o l n N m . W d W N d W d

m o d o m c o

Y Y a l a l M M k h d d bk-4

Al I

P P 4 4

% u - k e, P

3 c c

E

U

2 3

-+ +J .3

.+ +

d

c

d d a, k d M d

d a, a l k - e 3 0

0 N r- N

A

2

v

5 d w Y

3

4 2 Id 0 b

E ". " 0

I Z C

87

APPENDIX A GER-12842, VOL I

0 W 0 m r - -l N m m u .

r - 0 m m In . dl . * N m m N -l m 4 4 f a m .. m H . o m a . a . r - N * O . N W r - \ m . . a . . a m . m D 0 r- . . . . 0 . . - l z N . m m + - 4 W d - l O ,-4 N m m o o - l o I d o

0 0 m a l * - N * . r-

m a m m m - m - 4 d W

e . N A N d m - d m d N N a m d . o 0 - 0

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4 s 9 x

a 3 w 0 M c c c M a, e d

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4

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c

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w

a, + a, a, k M 0 a k a, a v

a, a

n * w

c o .+ g ' * II .+ v o o

U N W

I1 I1 .,- 0- a, 5 5 L .,- .r(

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a a, d

3

Y

4

i)

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Y

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d

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d

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4

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c * L

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N O O C O V . r-.- ' m m N 4 a N " r - d

N r - m o o o o o r - . m . r - C O

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4

m m o o o o o r -

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m 0 * o 0 o m . C O N O

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* m m o o o o o w . * .oCO O * O m N

+ U

Y v

rd 0

n U

c)

S W

U

c3 c3 a, 0 U

M Id

.+

.+

6

APPENDIX A G E R - 12842, VOL I

m l n a m l n m 9 m m In

O < - t - d 0 c o c o m . . e m . r- r+l . . . . d \ d t - d - 0 l n m a H m - 4 0 v) r+l K s 0 0 4 0 I z d

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4 4 9 x

a 3 il 3 M c c c M a, P

d

c

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Y

m *

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0 a, m

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A U d Q)

0 d 0

d c d a

u

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x, k 0 L 4

c

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v)

h a,

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c

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d k a,

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<n V - k QJ P

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c

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Y

d

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4-2 - d 0

n u Y C e,

u % * al 0 u M d

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d

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a a, v) d D - 2 M .3

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d h e, a, u a,

73

d 0 b

Y

i

*

APPENDIX A GER-12842, VOL I

9 -4 N m N d m m m

4 z m N * ul m m m G- m m v o 0 m N . . m . . r - r - . L l i s d m . . . . d \

1 - 4 * . m N H F d N , + m o * N co N 0 0 0 0 I 2 0 & * m N - 0 0 ' O N F O

m m a ul * * L n Ln 4 N W * N 6 m F N 0 m N . . N . m m r - m 4 O N N N r - 0 . 0 0 o m * * 6 N N N . 4 0 - 4 4 N d m O * N 9 N 0 0 0 0 I 0 0 . . . . a m . 0 9 9 9 . . . . 0

3

* C

x

R a, V

rd a, k

rd

a, R

3

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2

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3 3

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3

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d

5 2

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42

a, k

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m k e, u d

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c)

+

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m a N c o

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B

APPENDIX A GER-12842, VOL I

t- N rr) Q) a m t- t- a m 0 * m * m N . Q) e m m N 0 W C O . . m . m N a m N . m m . . a . * N - 4 0 . m o m a . . - 4 . . t - t - . m CO VI to . . . . 0 . .

a * t - . m N t - d N - 4 m O 6 N d N 0 0 - 4 0 I O 0

m m m t - a m . .

- 4 - 4

m m -4

* 0 -4 .-(

N

rr)

2 N

t- m

0 2 - 4 N P C O d + N O 0

0 0 - 4 0 . . . .

* 0

0 I

Q) C O N m - 4 0 0 . .

a . Q)

N O

m 0 N N t- N CO rr) * m m -4 m m

. . 0 . m N Q ) m m . o t - . . t - m . o . . m . . a m . d t- a -

, P P ~ 4 4

cn E

i o

* H

G

a a, m d ~e

i 2 M .3

3

* Id 0 'b

G 0

V al 10 d P a 0) k .3

k

; 7 0 > M G

M d x u

3

.3

2

E" 1 0 > k 0

Id 0 al u al V a al

d

+

*

3

* 3 '3

3

al a w 0 2

* G

; x 0 a a d a, k 1 m 10 al k a u

3

*

.3

E z a"

k 0

d a,

a, u 0, a '3 0

c

*

4

.r( * 2 x M

0 '3

? .3 a d

a, m k

:z b m

' 3 d o u

' 3 M o u m 0

G 0 .* * .A

m 0 a M u

E i)

m x m al

m * .+

0 a 0 E U

c 0 .+ 4-2 .r(

m 0 a a u

E * m x m a,

m 0 a

* .+

E u

h

P

Eo-

u +

u - a a, +

.r( $ &I

m w

h

* a,

.3 3 3 a a d

m d M G 0

6

E

0 m m

- .3 4 2

3 '3

.r(

'3

d E -0 a, a :

k a, x d 3

2 d a c 1 0 n w 0

u a, w w a,

m m

*

$ * G

k

8.

3 N 3 H

4

s 9 x

a 2 '3 0

M G G G M a,

.r(

.3

n CI

a m c Y

; E u 0 a, m

E c1 .r.

c u a

L 4 0 d 0

a c Id a

.3 Y

+

3 : &

c

k d e

m U

m k al U d

d c U

o, U

... c)

...

Y

3

2

M a a 0 -

$ S 2 w k

W

In 0

... o, 3

u v)

.r( c)

U

E ". 0 0

S C

VI " . V I 9 0

o m . o . . u , F m a - I . - I F

dm ~m N - I A A

u,

m m m - 4 m

o m . N . . m r - m a c o . 0 0

~ - 4 m ~m - 4 - 1 * a

h

% u - k a, n E 3 c c U

3 3

d

c:

d Id e, k d M d k

... Y .3

... c)

n

k o, Y

E" Id 6

h 3

Y

Y - d 0

n u C o,

U

b+ % a 0 U

M d

42

... ...

6

c k U

d

O. 0 31

. N r n * m a r - 0 0

. . APPENDIX A GER-12842, VOL I

F m m In c o d W to

c o c o 0 * N 2 N d+ * 9 0 + A a m . . 9 . . m o . co t-' 4 . . . . . 0 . . m 4

L n ' \ m a a . d N d W O * co co O O d O I 0 0

a F N M O . N O N . F - W m o . 0 9 .

f

c 0

V m m Id P

c M

Y

-+

i 2 Id c 0

d

c

.+ Y

3 '3

.3

m Id Ma,

2 0' + .3 m

5 : 4 M

I a, a ' 3 c 0 0

E 3 0 > -0 m d

d

0

+

Y

4 '3

-+ w

3

9 0 k Y

u

k 0

d

a, a, U a, a w 0

c 0

*

A

.C U

2 x M

0

3 a d k

a, m k

'3

m .+

? ? z : 2 $ e m

a, 4

m -

c 0 .+ Y .+ m 0 a M U

E Y m x m m m Y .+

0 a 0 E U

a, m k M

V k m a -

m

m Y

2 ; d .+

8 - k x a k a d d a

- e

N 3

4 5 3 x

a : w 0

M c c e M a, P

Id

c

-4

.A

U

0 Y

; E U

m m m

E Y .r(

2 u d

-4 0 c 0

d c d a

.r( 4-2

4

x, h

- 96-

m 0

0 U r

c

CA

h

M aJ a 0 N d - aJ c:

rd W Y

P

U

u)

k

.+ *

.+

aJ 4 2

V ld

m m m N . m o m r -

m N m m m ~ d d N

. . o w . o m i N I n I - 4 . m m

In w N . - 0 3 * .

o w . N e *

m r u m m m d d r - d m i N m m . 0 0

m N In N . m m m . . o o . w . r -

m * N O W . c o d m N m m ~ d o r - l - i

u w

k aJ P

3 G r U

E

2 4

.+ * .+

.e

4 4

d

c

d Id aJ k d M d k n

C

P aJ In

c k U

d

APPENDIX A G E R - 12842, VOL I

* r- m N . m w

#-I a m . o m . 0 - 0

I , . . m m o * r - d + N m o d . a * m r n 4 . 0 6 . 4 " <

. . . . m \ 0 . . m P - N w a O \ - 2 * . s ' i m - m N m i * - a - m 0 . d 0 0 0

c a e, m rd n c M

42

.r(

$ 2 d

E" 1 0 > k 0 d e, e, u e, V V e, rd

4

*

+

c 3 w El

.r( c * .r( * .r(

.r(

*

rd

c

c

E" x 0 a e, a d k e,

3

c.)

n E

5 1 c

E 3 0 > a

rd

c

0

3

* + w .A

w

2 k

C e, u *

k 0

d e, e, u e, a 0 c 0

rd

x M

0

m 1

d

e, m k

*

4

c(

.r( 42

w

s

:z B m

k 0

d e, a, U e, V w 0 G 0

*

4

.r(

U

2 x M

0

m 1 a

13

.3

2

.o, 3

d G V

* k d d z g d m

c 0 .r( * .r(

m 0 a M u

E Y m x m e,

m 0 a 0

* .r(

E U

e, e, k M a,- a k e, a Y

P

EV

u +

u - V e,

rd *

E .r( Y

m w

X a

a

.r(

5 2 c( 0

M c c d M e, .n

rd m c

.r(

.r(

L)

.c)

E" E u a, e, u)

E Q)

c rd

Y -r(

U

k-i 0

0

Id c d a

..-I Y

4

2 h

*

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d d .r( ... c ) Y .e ... I $ &

m

m k 0 U

d c U

W

U

U ... Y

... Y

2

d

.4 c c

bo al a

3 - u - d k d M

2 tl

w t-c 3 c-1 c-1

2 Y U d P I a al Y U 7 Y

I

m a t-c

U .3 * .r( m & al

U Y

c

E * " 6 = ; E

rr) 0-4 a 3 d r N 9

* . o m . * . . 0 0 0 o m d . a 3 N

N d m N m N d d r t -

m P m 0-4 m a m N - . oco . o . . o m o m I n . m o

N - 4 m N I n N d -4N

rn

m In O H m 9 0 3 . . o m . m . . oa3 o m N . 0 9

N - 4 m N m N d m t -

m 0-4 N m a 3 . . 0 9 . - 4 . . oco o m P * a m

N d m N N d d c y 9

k al P

3 E I:

E

U

3 3

-4 &i .r(

.r(

Y

d

c

d al k 7 m al k a U

'2 a" d C

k e, P

3 C c

E

U

3 3

.3 Y .d

.r(

Y

d

E

d al a 3

4-l -4 Y d

e

c U

d

... * ... d C

d e, k 7

... *

42

2

E a

* 3 3

d 3 U ...

<* u w

k o P

3 E Ld

E

U

2 3

.+ * .+

... Y

d

C

d d a, k d M d

h 0 *

E" d s

3

42

4.2 w

d 0

n u c! *

.r(

-4 U

-4.4 * al 0 U

M d

6

C 0 a a, m d n 2 M .+

i k 0 d

o al U

*

3

B

Irr 0 m m

d C 0 k U

c)

: C k U

d 3 ,

* rd 0 e

~ APPENDIXA GER-12842, VOL I

r- 9 N a N m m 0 N

e g . m + o m 4 N d N O rr) - co 4 0 0 0 0 I z d

r - r - m d 0 o- N * w o r n m o 4 * m a l m o . O d - . d N 6 0 . . m . . o m . m r- N w . . . . d \

m l- 9 Q) m r - m N

d 9 0 d 4 m m

9 2 m . m ' N S d N d N 0 9 4 u 0 0 4 0 I 0 0

1 - 0 m * 0 0 m c m . + o m m o . 0 9 . . d 0 1 - N O 0 . N O N \ . * . . o m . N Q) N . . . . 0 . .

d N m d . r - m . o 4 0

r n d N r- w 0 * G G - 4 O N

A \ . . o - . . o m 0 . ; d m . . m z N . N 4 N d N d N 4 d 4 a 4 d d . d 0 0 0

m m 0 m . 9 r - 0 m o . o r - .

d 0 k 0

8

U '3

2 2 \

0 W

I I

x

c a

Y .r(

m

F

2 .+ 3 U

al

1 0 > k 0

id

al e, U e,

a e,

cd

E 3

*

3

* 3

I al a '3 0

k d *

* m

E 0 h '3 Y

E" .+ U

C 0

d

C

.+ 42

d

- 2 2 e,

.+

vla

C

d

d

d

.+ U

.+ * .+

.+ Y

E" x 0 a e, a d k e,

4

*

n E 2 c

2

1 0 ' -0

d

C

0

3

* 4 '3

.+ '3

2 k Y c u

k 0

ld

al

e, U al '0 '3 0

e 0

*

3

.+ * 2 x M

0

3

ld

al m k

'3

m

ti

:; z : 2 g b m

al U .+ m 0 a 0 E U

'3 0

e 0

ld x M

0

.r( U

'3

m 2 -0 a u I d h 4 k $ z g .41 E d 2 Y

al 4

2

E

2

a ld

0 k '3 w

M .+

t k 0 Y

2 3 al U al a 0 '3

s

0:

0 k h

V n

C 0 .d U .+ m 0 a M U

E U m >.

0, I-' .+ m 0 a 0 V E

0 al k M

P k al a w

-4 -4

N 3

W 4

4 s 6,

x

a 2 '3 0

2 .+ C d M al

-+

n Y

d m c *

; E 0 U

P) al m

E Y .d

c u d a, '3 0 C 0

.r( Y

d a 4

1 h

* 0) M k

G

w U

m k a,

U

.r( u

.+

*

d 5 d

a, U z

2 >

* a, M

d H

k 0) Y

E d .3 n

M P)

0

a W

U

6

c m M I m m m

3

Y

$3

d a, k d M d

U

E *. Q ) O Z C

m r- 0 4 O N D m . . o m . o . . oco o m c o . r - c o

N - l m N 9 N - l - l *

M

4 2 W c W

k Q) P

3 c c U

E

3 4

.+ * .r(

.r(

*

d

C

d a, k 3 m m a, k a U

'2 a" d C

k a, D

3 C c U

E

3 4

.+ * .3

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rd

d

d a, U 5 * .,. * 4 4

4n V Y

k a, P

5 d e

E

U

5 4

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.+ *

d

d

d d a, k d M d

2

4

Y

* Y

d 0

n V * C a, .+ U .+

W W

a, 0 U

M d

5

C

U a, m d P

2 M -4

i k 0

d a,

a, U

*

4

d

Fr

m

d C 0 k U

0 u-l

Y

&

d 0 k U

&

APPENDIX A GER-12842, VOL I

c 0 -0 e, m d P

c 4 2

M .r.

; 2 d c 0 .r( *

2 w h

c 0

a al m d P a a, k

5 G- a, k

.3

E" 5 0 > M C M d 3

4

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U

a"

='tl 5

5 4

0 N

II

x 10 C a, a M c

* .r(

E

2

Y w

8 ff \

0 m

I I

x 42 .r(

: a M e 3 V

.r(

a"

; 1 0 > k 0 d a, al V a, a a a,

d

3

*

4

* 3 w 3

I a, -0

0

k d

W

*

Y m

E 0 k w Y

.r. E" c)

c, 0

d

c

.r( c)

3 w - .r.

a; .? 0) 2 E : g ad m a

c 0

d

C

c

.+ *

.r. * .+

.r(

*

E x 0 a al -0

d k a, D

3

*

E 2 5 3

Y c

E x a a, a d a, k 5 m m a, k a V

3

*

'2 2

E 2 0 > a a,

d

C

0

42

3 W

-r(

w

2

E,

0 4 2

u

k 0 d a,

0) V 0 a W 0

c

d k x M

0

5

d

Y

3

.r( 42

W

m

6

al m k

:2

H m

a, * .3 m 0 a 0 V W 0 c 0

d x M

0 m 3

d a l k k

E

.r. c)

w

6 a

0 4

2 E i: e a b

H m

al 3

2 z E

2

a

k w w

M .r.

i k 0 * 2 + 0 V al a 0 w

2

s : k -

Q ) d U n

c 0 .r. c) .r(

m 0 a M V

E * m x 10

al

m * .r(

0 a 0 E u

0

m 0 a a

.r( Y .r(

V

E Y m x m 0

m 0 a 0

Y .r(

E u

h

0)

k M

a k e, a - aQ u

II

al M rd 0 > rd - 2" u a a,

d U

E .r. 42

w

h

* 0) d

X 0 k a a d

d M c

rd

C

0

E .r(

w

m

.r( c)

4 w .r(

W

m m d

a al a

E

k al x d 3

5 d a E 5 0 n * 0

V al W W al

m m

*

2 * c 0 k rd a

i: N 4

0 4

4 6 9 X

a %

? L 4 0

.r( c e M e, P

d

e

.r(

*

m *

E E 0 u Q) al m

E P)

s u rd al

0 c 0

d c d a

Y .r.

Q-4

.r( Y

d

1 2 k

- 1 o v

GER-12842, VOL I

APPENDIX B - REFINED POINT-MASS

TRAJECTORY COMPUTATIONS AND

TRANSIENT HEATING CALCULATIONS

The f igures in this appendix present the space / t ime

and envelope transient t empera tu re h is tor ies of the

dece lera tor envelope fabr ic fo r the en t ry cases in

Table I11 of this report . The envelope fabric in a l l

ca ses was dacron.

-103-

32

2E

2c

16

12

8 m- 2 X

I- W W LL4

W 0 3

I- J 4:

-

b

0

T U C K E D - B A C K B A L L U T E _- A N D A I R M A T C O N E

1 2 3 4 5 M A C H N U M B E R

I60

140

120

100

80

60

40

- In

20 0 u W

W 5

In - -

' 0 I-

480

40C

32C

24C

- t W I Z W (I: 160 I 4: IL

W (I: 3 I- a (I: W a 8C 5 W I- W

0 J W > z

-

a

W c - MACH

APPENDIX B GER-12842, VOL I

1 N U M B E R

1 I

- -- TUCKED-BACK B A L L U T E

---AIRMAT C O N E T L I N l T l A

4 5 6 2 3

Figure B- 1 - Space /Time and Envelope Transient Tempera tu re versus Mach Number (Tra jec tory A l )

28

24

2c

16

12

8

m- 2

I - 4

X

W W ll.

W 0 3 I- I- -1

- -

4 0

T I M E -

r T T A C H E 1 A L L U T E

M PACT

70

$0

50

$0

30

20

10

0 0.8 1.6 2.4 3.2

MACH NUMBER

- VI 0 z 0 u W VI

W

I-

- E

. <

, APPENDIXB GER-12842, VOL I

140

12c

1 oa

BC

60

4c

ORDER OF A PPROX I M

- k W I z W U I a

W U 3 l- a U W

r W I-

t 20

a

C

M A C H N U M B E R

I I --- - A T T A C H E D B A L L U T E

- - - TUCKED-BACK B A L L U T E

-.- A I R M A T CONE

F i g u r e B-2 - Space/Time and Envelope Transient Tempera tu re v e r s u s Mach Number (Tra j ec to ry B3)

- 10%

3

2

2

21

11

1;

m- Z t X

I- W W LL

W 0 3

I- -I

4 -

t

a 0

0.4 0.8 1.2 1.6 2 . 0 2.4 MACH NUMBER

I60

I 4 0

I20

I O 0

30

io

I O

ffl 0

10 = 0 u W

W I I-

ffl - -

APPENDIX B G E R - 1 2 8 4 2 , V O L I

, MATERIAL U N I T WEIGHT (LB/SQ FTI

1ST APPROXIMATION 2ND A P P R O X I M A T I O N

40k A T T A C H E D B A L L U T E 0.0204

TUCKED-BACK B A L L U T E 0.01 12

I A I R M A T C O N E 0.078 Z

O . O P 5

0.016

0.012

0.049

W U I a 5 2c W K 3 F

U W Q 5 W

a

0.4 0.8 1.2 1 .6 2 . 0 + o MACH NUMBER

F i g u r e B - 3 - Space/Time and Envelope Trans ien t T e m p e r a t u r e v e r s u s Mach Number (Tra j ec to ry 19)

-1qe

5

5(

41

4(

3;

2

11

I

0.2 0.6 1 .o 1.4 1.8

MACH NUMBER

60

4 0

20

00

&/-/

In 0 z 0 u W In

W

t-

- 5

I X B GER- 12842A, VOL I

240-

zoo

160

120

80 - k W I z W LL I U - 40 W LL 3 I- U LL W

I W I- 01

a

O R D E R O F A P PROX l M A T l 0 N W / A (LB/SQ FT)

1ST 0.01 1 - ----- ’ 1

1ST

-= -=- -- .- 2 N D

2ND

2ND 0.019 -- ---- ----- --E --e-- 3r ---- 1 1 S T

I

2ND --- 1 S T

--(I

t I N I T I A L I I - T R A I L I N G B A L L U T E - - - - A T T A C H E D B A L L U T E

- 0 0 TUCKED-BACK B A L L U T E

-. - AIRMAT C O N E

0.2 0.6 1 .o 1.4 1 .8

M A C H NUMBER

2.2

Figure B-4 - Space/Time and Envelope Transient Tempera tu re v e r s u s Mach Number (Tra jec tory 22)

Revised 21 October 1966 - 1 1 1 - 2 ,

MPACT,

,TIME

TUCKED-BACK B A L L U T E , AND ATTACHED B A L L U T E

I 1;' I

I I

I

---- A T T A C H E D BALLUTE - -- TUCKED-BACK B A L L U T E

1.4 1.8 2.2 0.2 0.6 1 .o M A C H N U M B E R

240

200

160

120

80

40 - In 0 z 0 u W In

W z

3 +

- -

. .

APPENDIX B GER-12842 , VOL I

140

ORDER OF APPROXIMATION

W / A f LB/SQ FT)

120 2 ND -- -

2 ND -- .- - - - - ---,--- - -- 1 S T 100

- -- TUCKED-BACK B A L L U T E

80

h 0.01 9 I ‘1

Figure B-5 - Space/Tirne and Envelope Transient Tempera tu re versus Mach Number (Tra jec tory 23)

- 113’-

I TIME-

0

A / T R A I L I N G B A L L U T E

I I

- T R A I L I N G B A L L U T E

- - ,TUC K E D-BAC K B A L L U T E I 8

T R A I L I N G A N D TUCKED-BACK B A L L U T E S

20

0.2 0.6 1 .o 1.4 1 .e 2.2

M A C H NUMBER

I .

80.

60

I

40

20

0

YPPENDIX B GER-l2842A, VOL I

I 1ST A N D 2ND APPROXIMATIONS FOR B O T H D E C E L E R A T O R S

\

M A T E R I A L U N I T WEIGHT (LB/SQ F T )

1ST APPROXIMATION 2ND A P P R O X I M A T I O N

T R A I L I N G B A L L U T E 0.018 0.015

TUCKED-BACK B A L L U T E 0.0112 0.012 -

0.2 0.6

MACH NUMBER

1 .o 1.4 1 .e 2.2

Figure B-6 - Space/Time and Envelope Transient Tempera tu re v e r s u s Mach Number (Tra j ec to ry 3 0 )

Revised 21 October 1966 - 1 1 u -

GER-12842A, VOL I I

APPENDIX C - DISCUSSION O F DYNAMIC STABILITY

ANALYSES

1 . INTRODUCTION

The determinat ion of the dynamic motion charac te r i s t ics for a recovera-

ble space vehicle landing on the sur face of M a r s with attached o r t ra i l -

ing aerodynamic dece lera tors is a p r i m a r y requirement .

cha rac t e r i s t i c s will predominantly affect the design of t e rmina l impact

control s y s t e m s , whether they a r e of the hard- o r soft-landing type.

The motion

Additionally, a s shown by the r e su l t s of this study, there is relat ively

l i t t le weight advantage indicated for a par t icu lar dece lera tor configura-

tion on a drag per formance basis.

t icular configuration largely could be dictated by dynamic per formance

cha rac t e r i s t i c s .

Consequently, the choice of a pa r -

The weight analysis developed in this study was based on s ta t ic a e r o -

dynamic loading relationships with empir ical ly determined, quasi- s ta t ic

load, t empera tu re and design f ac to r s employed to account for operating

environmental effects and ma te r i a l cha rac t e r i s t i c s . This weight analy-

sis of necessi ty preceeded the dynamic ana lys i s , a s suming adequate

aerodynamic stabil i ty of the var ious configurations and l i t t le dynamics

interact ion with the decelerator strength-weight requi rements .

interact ion is discussed subsequently in this appendix a s re la ted to the

attached dece le ra to r configurations.

This

T h e development of a n adequate mathemat ica l model formulated for u s e

with high-speed digital computer equipment is a prerequis i te to analyze

dynamic motion and to secure resu l t s within reasonable t ime sca l e s .

The dynamic motion about the flight path of a n aerodynamic expandable

Revised 21 October 1966 -117-

APPENDIX C - DYNAMIC STABILITY ANALYSES G E R - 128424, VOL I

dece le ra to r is quite complex; par t icu lar ly , i f spin about the longitudinal

axis of the en t ry capsule is p re sen t p r i o r to deployment of the dece le ra -

to r device. Spin may be induced intentionally o r be p re sen t inherent ly

f o r rotationally s y m m e t r i c bodies t r ave r s ing entry-f l ight paths .

tentionally induced spin (usually sma l l , about 1. 0 r ad / sec o r l e s s and

not intended for spin s tabi l izat ion) p r i m a r i l y min imizes deviations f r o m

the flight path as a r e su l t of l a t e r a l cg to le rance and e n s u r e s s y m m e t r y

of heating over the forward portion of the en t ry capsule .

In-

During the ear ly IRBM and ICBM nose cone development p r o g r a m s , i t

was found that nose cones not intentionally spun would develop inherent

spin during en t ry through the e a r t h ' s a tmosphe re as a r e s u l t of l a t e r a l

cg to le rance and a s y m m e t r i c ablat ion when'incorporating this method of

heat insulation.

the o r d e r of 0. 2 r ad / sec .

ax is control sys t em with aerodynamic o r je t - reac t ion cont ro ls .

Typical sp in r a t e s encountered in this m a n n e r w e r e of

The a l te rna t ive to spinning is anac t ive , t h ree -

F o r the c a s e of a n aerodynamic body with a t ra i l ing aerodynamic de-

ce l e ra to r , there a r e 18 deg of f r eedom when the motions of the r i s e r

and suspension s y s t e m between the forebody and t ra i l ing dece le ra to r

a r e considered.

- i. e . , forebody, r i s e r and suspension l i nes , and t ra i l ing dece le ra to r can

be t r ea t ed a s rigid bodies.

w e r e considered fo r each component, then the s y s t e m has 36 deg of

f r eedom.

t r a j ec to ry of an en t ry body and t ra i l ing d e c e l e r a t o r f r o m deployment to

impact , using the requi red integrat ion in t e rva l s , would be prohibi t ive

o r a t l ea s t unrea l i s t ic even with the highest speed and capaci ty digi ta l

computers available.

This a s s u m e s that each of the s e p a r a t e components ,

If f lexibil i ty and tors iona l deflection modes

The solution of this motion descr ip t ion during the r e a l - t i m e

Exper ience has indicated ( a t l e a s t f o r pu rposes of p a r a m e t r i c analy-

s e s ) that the physical descr ip t ion f o r the dynamic motion of a body can

be approximated reasonably by neglecting f lexibi l i ty effects o r by in-

troducing this considerat ion a s a modif icat ion to rigid-body p a r a m e t e r s

- 118-

I D I I I I I I I I I I I I 1 I 1 I I

I I I I I 1 I I I I I I I I I I 1 I I

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

and coefficients. Additional simplifications in the mathemat ica l formula-

tions can be made with appropriate assumpt ions and approximations such

a s l inearization of non-linear t e r m s , s m a l l angle approximations, in-

var iant p a r a m e t e r s , constant coefficients , etc . F o r bodies defined as

having rotational s y m m e t r y and weight distribution, the proper choice

of body re ference axes about and along which the motions can be de-

sc r ibed el iminates c r o s s products of iner t ia and decouples pitch and yaw

angular r a t e s f r o m the rol l mode s ince the t r a n s v e r s e moments of i ne r -

tia of the body a r e implicitly equal.

accelerat ing in longitudinal flight o r is nea r te rmina l velocity conditions,

the longitudinal force equation usually m a y be s u r p r e s s e d and the space-

t ime h is tory adequately described by sepa ra t e , m o r e s imple poin t -mass

t ra jec tory computations .

Additionally, i f the capsule is not

2 , ANALYSIS

Goodyear Aerospace has developed in Appendix B of Volume 11, equa-

tions of motion with six and eight degrees of f r eedom to descr ibe the

cha rac t e r i s t ics of composite sys t ems with attached o r t ra i l ing ae ro -

dynamic dece lera tors entering planetary a tmospheres .

tions w e r e developed for use with the IBM 360 ,computer s y s t e m availa-

ble a t the Goodyear Aerospace computer faci l i t ies .

planation of this formulation is made in this appendix.

i l lus t ra te what fac tors and p a r a m e t e r s a r e important in the force and

moments affecting the motion cha rac t e r i s t i c s of composi te en t ry capsule/-

dece lera tor sys t ems , the following simplified equations a r e s e t for th

using conventional a i r f rame-dynamic-stabi l i ty notation.

i s not the s a m e as employed in Appendix B of Volume 11.

The formula-

No additional ex-

However, to

This notation

F o r the cases of a n en t ry capsule with attached dece lera tor configura-

t ions, the fo rce and moment equations m a y be wri t ten in t e r m s of pr in-

cipal axes of a body.

pendent of the angular motions about the axes and a r e constant with the

resu l t that' all products of inertia a r e eliminated.

Thus, the s y s t e m moments of iner t ia a r e inde-

-119-

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-12842AY VOL I

a F o r c e equations

Moment equations

The summation sign implies consideration of all appror ia te aerodynamic

factors f o r both the vehicle and dece lera tor .

and a s used in the study, the t r ansve r se moments of iner t ia w e r e defined

a s equal, eliminating effects of iner t ia coupling in the rol l -angular acce l -

erat ion equation.

pendix A, the iner t ia coupling effect is about 10 percent of the c ross -p lane

angular velocity for e i ther the pitch o r yaw angular acce lera t ion equations

The effect will be osci l la tory in accordance with the sign of the c r o s s -

plane angular velocity s ince the ro l l damping was negligible and the roll

ra te remained constant in the computations of this analysis .

roll-angular accelerat ion equation is eliminated f r o m fu r the r discussion

in this appendix.

As previously noted above

Using I tems 2 1 and 23 of Tables A-I11 and A-XI of Ap-

Thus, the

The pa rame te r s (g) and (c) given below f o r t r a j ec to r i e s 19 and 22 a r e

a See Lis t of Symbols a t the end of this appendix f o r definition of t e r m s .

- 120-

1 I I I I I I I 1 I I I 1 I I I I I I

~

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

I I I I I c I I I I I 0 1 I I I I

evaluated a t init ial operation and nea r te rmina l conditions for each attached

dece lera tor configuration f rom Tables A-111 and A-XI.

P a r a m e t e r s for t ra jec tory 19 (VM8)

AB

(SI i 65

(g) 1 2 . 3 t

91

P a r a m e t e r s for t ra jec tory 22 (VM7)

AB

(,) 1 2 . 3 t

(E)i 6 6

1 3 . 9

TBB AC - -

85 59

14. 4 1 2 . 4

147 8 5

25 17. 8

TBB AC - -

7 4 52

13. 5 1 2 . 9

106 65

19. 4 15. 1

The variation in values tabulated above a r e indicative only of the differ-

ences in geometry of the decelerators s ince, for prac t ica l purposes , the

dynamic p r e s s u r e , q, i s the s a m e and the m a s s (m) i s identical for a l l

cases . Note that the values for these p a r a m e t e r s in both the force and

moment equations a re of comparable magnitude.

-

-121-

The fac tors compris ing the aerodynamic t e r m s contained in the force and

moment equations with a l l coefficients r e f e r r e d to body axes a r e given be-

low.

F o r c e equations:

Moment equations :

X M 7 = c ( C , ) = -Cp - 0 in this study V

P 9Ad

d M Y = C ( C m ) = c m c y + km q t cm

P 9 cy cy qAd

I I I I I I I I I I I 1 1 I I I 1 I

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

where typically (assuming sma l l angular displacements) - r . * ..

u = xx+;i;+.;:

' vi '- cyu c y = V2

VL

-122-

L

APPENDIX C - DYNAMIC STABILITY ANALYSES GER- 12842A, VOL I

Note again that the above notation i s not the s a m e as that employed in

Appendix B of Volume I1 but is introduced in this appendix to gain a n

appreciat ion of what aerodynamic t e r m s m a y be important .

the parenthet ical products , (ap) and (pp), which essent ia l ly provide

damping fo rces and moments , a r e general ly r e f e r r e d to as the kinematic

coupling t e r m s in conventional a i r f r ame-dynamic - s tabi l i ty ana lyses .

These t e r m s can have a n appreciable effect on the dynamic motion c h a r -

a c t e r i s t i c of a spinning body i f l a rge angular excurs ions in angle of

a t tack and yaw a r e encountered.

t e r m s fo r a constant ro l l ra te can a l te rna te ly a id o r aggrava te the os -

cil lation tendency of the sys t em in the c ros s -p l ane modes of motion.

Note that

Note fu r the r that the effect of these

3 . RESULTS FOR ATTACHED CONFIGURATIONS

In this study, all aerodynamic damping t e r m s w e r e neglected in the

force equations.

equations.

account for the kinematic coupling a s defined in the above notation, the

coupling effect m a y be in te rpre ted a s being p resen t through the formu-

lation of the angular r a t e mat r ix in Appendix B of Volume 11.

P i t ch and yaw damping was considered in the moment

Although no separa te coefficient t e r m was introduced to

Now, consider ing the aerodynamic fo rce and moment equations above,

the evaluation of the pa rame te r (-) is made f o r each at tached decel-

e r a t o r configuration a t initial operat ion and n e a r t e r m i n a l conditions a s

follows :

d 2v

P a r a m e t e r for T r a j e c t o r y 19

AB - TBB AC - d (rv)i 0.021 0 .024 0. 02

0. 041 0. 047 0. 04

-123-

1 APPENDIX C - DYNAMIC STABILITY ANALYSES GER-12842A) VOL I

P a r a m e t e r f o r t r a j ec to ry 22

- AB TBB - AC

0 . 0 1 4 0 . 015 0. 013

(nJt 0.025 0 .028 0 .024

The values f o r the p a r a m e t e r s given below a r e taken f r o m Tables A-I11

and A-XI of Appendix A ( I tems 25, 26, 27, and 28):

P a r a m e t e r s for t r a j ec to ry 19

AXcp

V D

AC - - AB TBB

-0 . 92 -1 . 104 - 0 . 8 7 6

C = Cy (pe r deg ree ) 0. 01 0. 02 0. 005 P

(pe r d e g r e e ) - 0 . 0092 -0 .0221 -0 . 00438 = c = c - AXCp

m "0 NCu D V

C (Y

(pe r rad ian) 9

- 0 . 2 7 -0 .336 - 0 . 2 8

P a r a m e t e r s for t r a j ec to ry 2 2

AB TBB AC - - AX

D CP

V

-0 .818 -0 .973 - 0 . 7 8 5

0. 005 (pe r d e g r e e ) 0 . 0 1 0. 02

= C (pe r d e g r e e ) -0 .0082 -0 .0195 -0 .00393 (Y "P

(pe r rad ian) -0 .208 -0 .258 - 0 . 2 1 8 (Cm cm CY

APPENDIX C - DYNAMIC STABILITY ANALYSES CER-l2842A, VOL I I

The aerodynamic f o r c e and moment equations at ini t ia l operation of the

dece lera tors reduce approximately to the following values:

F o r c e and moment equations fo r t ra jec tory 19

AC - - AB TBB

- - - -cx - 1 . 3 0 .99 1.43 c Fx - ‘D w

y= -c -0.01p -0.02p - 0.005p Y CF

qA

-0.OlQ -0.02Q -0 . 0 0 5 ~ - cN CFZ - =

qA

- (0. 0 0 9 2 ~ t - ( 0 . 0 2 2 ~ t - ( O . 0 0 4 4 ~ t 0. 0057q) 0. 0081q) 0. 0056q)

0. 0057r) 0. 0081r) 0. 0056r) - ( O . 0092p t - ( O . 0022p t - ( O . 00446 t

F o r c e and moment equations fo r t ra jec tory 22

AC - AB TBB -

- - - -cx - - CD 1 .3 10 .2 1 .435 c FX

qA

-0 .01p - 0 . ozp -0 . 005p

- 0 . O l Q -0 .02Q -0 . 0 0 5 ~ c - - FZ - -cN w - ( O . 0082Q + - ( O . 0 1 9 2 ~ t - ( O . 0 0 3 9 ~ t

0. 0039q) 0. 0039q) 0. 00284q)

0. 0039r) 0. 0039r) 0 . 0028r) - ( O . 0082p t - ( O . 0195p t - (O. 0039p t

The l inea r and angular accelerations due to the aerodynamic forces and

moments plus iner t ia coupling (approximated as 10 percent of the c r o s s -

plane angular velocity) a t init ial operation a r e as follows.

- 125-

APPENDIX c - DYNAMIC STABILITY A ~ A L Y S E S GER- 12842A, VOL I

L inea r and angular acce lera t ions f o r t r a j ec to ry 19

AB - .. x = - 8 4 . 5

9 = -0 .656

z = - 0 . 6 5 ~ ..

b = 0

6 = - 0 . 8 3 7 ~ - 0 . 519s - 0. l r

5 = -0 .8376 - 0. 5191- - 0. l q

TBB .. x = -84. 1

t; = - 1 . 7 6

r ; = o

.. z = -1 .7Q

4 = - 3 . 2 3 ~ - 1 . 1 9 s - 0. l r $ = -3 .236 - 1. 1 9 r - 0. l q

.. x = - 8 4 . 4

= -0 .2956 .. z = - 0 . 2 9 5 ~

r ; = o 4 = - 0 . 3 7 4 ~ - O.476q - 0 . I r

= -0 .3746 - 0 . 4761- - 0 . l q

Linear and angular acce lera t ions fo r t r a j e c t o r y 22

AB - .. x = - 7 5 . 4

y = - 0 . 586 z = - 0 . 5 8 ~

..

.. b = o 4 = -0 . 5 4 1 ~ - 0 . 257q - 0. l r

= -0 .5416 - 0 . 2571- - 0 . l q

- 126-

/

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-12842AJ VOL I

TBB

e 0

x = - 7 5 . 4

y = -1 .48p I .

.. z = - 1 . 4 8 ~

b = o 4 = - 2 . 0 6 5 ~ ~ - 0. 414q - 0. l r

= -2.065p - 0.4141- - 0. Iq

.. x = -74 .6

y = - 0 . 2 6 6

z = - 0 . 2 6 ~

p = o

.. 0.

0

4 = - 0 . 2 5 3 ~ - 0 . 185q - 0 . l r

E = -0 .253p - 0.1851- - 0 . l q

Refer now to F igures 27 and 28 of this volume.

s i s , i t is shown by inspection of the f igures and the reduced equations

above that the difference in the angular osci l la t ion cha rac t e r i s t ics

among the th ree at tached dece lera tor configurations is p r i m a r i l y af-

fected by the magnitude of the s t a t i c aerodynamic fo rce coefficient and

the s t a t i c s tabi l i ty marg in .

pandable a t tached decelerator configuration is of p r i m a r y impor tance tG

e n s u r e des i r ab le dynamic stabil i ty cha rac t e r i s t i c s fo r a specif ic t e r -

mina l des cent per formance .

tion of the osci l la t ion r a t e cha rac t e r i s t i c s for each configuration.

value fo r the damping factor (Cm

nea r ly the s a m e for each configuration ( s e e I tem 28, Tables A-I11 and

A-XI of Appendix A). motion a t ini t ia l operat ion where the configuration geometry p a r a m e t e r s

a r e introduced, the effect of the dece le ra to r geometry is substant ia l .

In t e r m s of the analy-

That i s , the s i z e and geometry of the ex-

This is fu r the r emphasized by cons idera-

The -t Cm,) is for p rac t i ca l purposes

9 CY

However, upon reduction of the equations of

Again, consider ing the above reduced dynamic motion equations fo r each

-127-

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-12842AJ VOL I

of the attached dece le ra to r configurations a t init ial operation, the deg ree

of accu racy may be approximated i n basing the previous weight ana lyses

on the assumptions that adequate stabil i ty would ex is t and that t he re would

be l i t t le dynamic interact ion with s t ress -weight requi rements .

t ranslat ional decelerat ion load along the longitudinal axis on the com-

posite entry-body dece lera tor is approximated as follows:

The total

where

g e = ea r th g ' s (32. 2 f t /sec/sec) ,

k = t r a n s v e r s e radius of gyrat ion of composi te

s y s t e m (from I tem 2 1 , Tables A-111 and A-XI

of Appendix A),

q and r = maximum values from F igures 2 7 and 28.

The composite s y s t e m l a t e ra l acce le ra t ion is approximated as :

Conservatively, the composite max imum g ' s can b e approximated as:

The following values a re the equivalent ea r th -g loads acting on the s y s t e m

for each of the at tached dece le ra to r configurations at ini t ia l operat ion f o r

t r a j ec to r i e s 19 and 2 2 :

- 128-

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

Ear th-g loads for t ra jectory 1 9

TBB AC - - AB - NI - 2 . 6 9 - 2 . 7 2 - 2 . 6 8

x , 9, r

Net e * , -1. 13 - 3 . 4 1 - 0 . 5 2 Y, z, g, r

Ntot -2 . 92 - 4 . 3 5 - 2 . 7 2

Ear th-g loads for t ra jectory 22

TBB AC - AB - N,. - 2 . 4 1 - 2 . 4 4 - 2 . 3 7

x , q, r

N.0 t t - 0 . 6 1 - 2 . 2 4 - 0 . 3 6 y, z, 4, ;.

Ntot -2 . 48 - 3 . 3 1 -2 . 4

Compare , now, the above tabulated values of g-loads with I t em 15 in

Table IV of this s u m m a r y report .

tucked-back BALLUTE for t ra jectory 19) that basing the strength-weight

requi rements of the dece lera tors on quasi- s ta t ic design s t rength, load,

and safety fac tors will, in general , tend to be conservative a s compared

to the max imum loads predicted by the dynamic analysis .

It is seen (with exception of the

This t rend i s on lyas f a r a s the attached dece lera tors a r e concerned. This

observat ion mus t , of course, a l s o be t empered in light of the a c c u r a c y

of the assumpt ions and approximations made throughout the p a r a m e t r i c

study. On the bas i s of previous engineering design experience and ap-

plication, i t is considered that the indicated t rends a r e valid.

4. RESULTS FOR TRAILING CONFIGURATION

As descr ibed in Appendix B of Volume 11, the trail ing dece lera tor i s

attached to the forebody through a suspension s y s t e m a s s u m e d to be

rigid. The confluence point is defined as the in te rsec t ion of the suspension

-129 -

APPENDIX C - DYNAMIC STABILITY ANALYSES GER- 1 2 8 4 2 4 VOL I

s y s t e m and r i s e r .

me t r i ca l relationship with respec t to the forebody r ega rd le s s of the

motion of e i ther the forebody o r t ra i l ing dece lera tor .

t rea ted as essentially a rigid rod f r e e to pivot a t any angle and in any

plane a t the confluence point.

In the ana lys i s , this point re ta ins a constant geo-

The r i s e r l ine is

The dece lera tor attached to the end of the r i s e r a l s o is defined a s r e -

taining a f ixed geometr ica l re la t ionship with the r i s e r (essent ia l ly a

rigid sphe re a t the end of a rigid rod f r e e to pivot a t the confluence

point).

having two degrees of f r eedom about the confluence point.

is influenced by the aerodynamic lift and s ide- force as a function of

angle of attack and yaw ( i . - e. , angular displacement of the r i s e r ) a s wel l

a s the d rag force and mass cha rac t e r i s t i c s of the dece lera tor . The spin

of the forebody i s not considered to affect the dece le ra to r motion as far

a s rotational, iner t ia l , and aerodynamic effects a r e concerned.

Thus, the analysis has neglected any consideration of i ne r t i a l o r a e r o -

dynamic coupling in descr ibing the motion of the t ra i l ing dece le ra to r .

The effect of the t ra i l ing dece lera tor motion and loads on the forebody

motion i s assumed to be t ransmi t ted as a tension f o r c e through the r i s e r

to the fixed confluence point.

Thus, fo r this p r o g r a m the motion of the composi te forebody and t r a i l -

ing decelerator has been descr ibed by the e ight -degree-of - f reedom

formulat ion presented in Appendix B of Volume 11.

The motion of the t ra i l ing dece lera tor and r i s e r is descr ibed as

This motion

Refer r ing now to F igures 27 and 28 and F igures C - 1 through C-6 of this

appendix fo r the t ra i l ing dece lera tor , i t is shown that the p re sen t ma the -

mat ica l model desc r ibes a n apparent coupling effect and resonance be-

tween rolling velocity and angular att i tude. This coupling causes the

composi te capsule motion to diverge to l a rge a t tack , yaw, and coning

angles f o r t ra jec tor ies 1 9 and 22. F igures C- 1 through C-6 have been developed f rom additional computer runs f o r the s a m e capsule/ t ra i l ing

dece lera tor charac te r i s t ics f o r different values of roll ing velocity. The

- 130-

I I

I

I I

1 I I I

1

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

I

0 0 0 - X

I- W W IL

W 0 3

I- -I

- t-

a

7

61

51

4

3

21

11

C

C- 1 - Decelera tor Oscillation Charac te r i s t ics f o r Trai l ing BALLUTE (Atmosphere VM7; Trajectory 22; p = 0 . 0 rad/sec)

- P A Y L O A D

t - ---- D E C E L E R A T O R

p 0.0 RAD’SEC

PITCH-YAW DAMPING = -S.Z/RAD I

5 10 15 2 0 25

A N G L E OF A T T A C K (DEGREES)

-131-

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

0 0 0 o i - 0 N 0 m 0 U 0 VI r. (D

(0001 x 1333) 3 a n i i n v

--r K

2

E 0 m 0 U 0 * 0 0

C-2 - Decelerator Oscil lation Charac t e r i s t i c s f o r Trai l ing BALLUTE (Atmosphere VM7; Tra j ec to ry 22; p = 0. 5 rad /sec)

1 I I

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

7 0

60

50

40

30

20

X

w 0 3 I- t -

- P A Y L O A D

-- - D E C E L E R A T O R I

I p 0.75 R A W S E C

PITCH-YAW DAMPING = -5 ,2 /RAD

5 10 1 5 2 0 25 ANGLE OF A T T A C K (DEGREES)

C-3 - Decelera tor Oscillation Charac te r i s t ics for Trail ing BALLUTE (Atmosphere VM7; Tra jec tory 2 2 ; p = 0. 75 rad/sec)

- 1 3 3 -

APPENDIX C - DYNAMIC STABILITY ANALYSES G E R - 12842A, VOL I

C - 4 - Decelerator Oscil lation Charac t e r i s t i c s f o r Tra i l ing BALLUTE (Atmosphere VM7; Tra j ec to ry 2 2 ; p = 1. 0 rad /sec)

- 134-

APPENDIX C - DYNAMIC STABILITY ANALYSES CER- l2842A, VOL I

h I '\.. Lo N Lo 0

m m

0 Q E \ "! Lo-

I

Lo -

LL 0 W J 0 z Q

>

C- 5 - Decelera tor Oscillation Charac te r i s t ics for Trail ing BALLUTE (Atmosphere VM8; Tra jec tory 19; p = 0 .5 rad /sec)

- 135-

APPENDIX C - DYNAMIC STABILITY ANALYSES G E R - 12842A, VOL I

,

,

- 136-

C-6 - Decelerator Oscil lation Charac t e r i s t i c s f o r Trai l ing BALLUTE (Atmosphere VM8; Tra j ec to ry 19; p = 1. 0 rad /sec)

APPENDIX C - DYNAMIC STABILITY ANALYSES GER- 12842A, VOL I

apparent e f fec t of ro l l coupling on the s y s t e m motion as descr ibed by

the present mathemat ica l model is s t rongly in evidence.

The drag fo rce and moment of the t ra i l ing dece lera tor has the na tu ra l

effect of providing stabilization for the composi te capsule/decelerator

s y s t e m as demonst ra ted by the case for the rolling velocity equal to

ze ro . Additionally, a s shown by the f igures of this appendix, the mag-

nitude of ro l l r a t e is important i n determining whether the s y s t e m wil l

converge to o r diverge f r o m a stable attitude in te rmina l descent . While

the possibil i ty of coupling and resonance is recognized to exis t fo r the

motion of a spining en t ry capsule with a t ra i l ing dece lera tor , Goodyear

Aerospace ' s experience with such applications (including cases of a

spinning forebody) has not exhibited general ly a divergence tendency, a t

l ea s t to the magnitude encountered in this study.

Therefore , the motion of a forebody with a t ra i l ing dece lera tor as p r e s -

ently decr ibed by the eight-degree-of-freedom formulation presented in

Appendix B of Volume I1 is not considered to be a completely adequate

descr ipt ion. The analytical descr ipt ion of the s y s t e m dynamics f o r u s e

of t ra i l ing dece le ra to r s should be studied and evaluated in g r e a t e r de-

tail than encompassed in this p r o g r a m in view of the impor tance for the

r ecove ry and safe landing of p lanetary en t ry vehicles .

5. CONCLUSIONS AND RECOMMENDATIONS

1. The present s ix-degree-of-freedom mathemat ica l

model describing the dynamic motion of composi te

en t ry body and attached expandable dece lera tor con-

figurations is adequate.

of this study, it i s not n e c e s s a r y to include additional

As shown by the r e su l t s

sophisticated p a r a m e t e r s such as kinematic a e r o -

dynamic coupling t e r m s o r non-linear var ia t ion of

coefficients with angular attitude for pre l iminary

p a r a m e t r i c analyses of the dynamic motion cha rac t e r - is t ics .

- 1 3 7 -

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

2. F o r the ini t ia l conditions established by the speci-

fied J P L ent ry t r a j ec to r i e s for this study c o r r e -

sponding to the t ime of dece lera tor deployment and

operation, the t rans ien t dis t rubance as a resu l t of

dece lera tor deployment does not r e su l t in excessive

angular excursions and r a t e s .

expandable dece lera tor configurations, the t rend is

toward convergence to reasonable magnitudes of an-

gular att i tude and damping of angular r a t e s of motion.

F o r all of the attached

3 . F o r the attached expandable dece lera tor configura-

t ions, the magnitude of the s ta t ic n o r m a l force co-

efficient and s ta t ic m a r g i n of stabil i ty (center of p r e s -

s u r e ) , which a r e indicative of the shape of the device

combined with the device s i ze and configuration geo-

m e t r y , profoundly affect the dynamic motion cha rac t e r -

i s t ics and damping of the composi te sys t em.

4. The computer r e su l t s using the p re sen t e ight-degree-

of-freedom formulation descr ibing the s y s t e m dy-

namics fo r a n en t ry capsule and t ra i l ing dece lera tor

point out that kinematic ( rol l -yaw) coupling effects

can r e su l t in angular att i tude and r a t e divergence

when an ini t ia l ro l l r a t e exceeding about 0 . 5 rad /sec

is present a t deployment.

a l so indicate that t he re is resonance , - i. e . , coupling

between the t ra i l ing dece lera tor and en t ry capsule

motion, that causes a pronounced divergence t rend .

The formulation presented in Appendix B of Volume I1

and the computer p r o g r a m have been de termined to

be mathemat ica l ly c o r r e c t and provide a n accu ra t e

descr ipt ion of the s y s t e m mot ion as descr ibed by the

formulat ion.

T h e computer r e su l t s

APPENDIX C - DYNAMIC STABILITY ANALYSES GER-l2842A, VOL I

5. In this event, the p re sen t e ight-degree-of-freedom

mathemat ica l model fo r the en t ry capsule and t r a i l -

ing decelerator does not appea r to be a completely

accu ra t e description of the s y s t e m dynamics.

observation s tems from actual f ree-f l ight experience

of Goodyear Aerospace personnel with s i m i l a r load-

ing environments. Apparently, m o r e sophisticated

f o r m s a r e required to descr ibe the dynamics s u c h a s

r i s e r - l i ne elasticity and additional degrees of f r eedom

to descr ibe confluence point motion, a t l eas t i n the

l a t e ra l planes. A descr ipt ion of the trail ing decel-

e r a t o r motion a t the end of the r i s e r line by two addi-

tional degrees of f r eedom a l so might be des i rab le .

Thus, i t appears that a t l ea s t twelve degrees of f r e e -

dom m a y be necessa ry to adequately descr ibe the

sys t e m dynamics.

Th.is

A survey should be made of pas t f ree-f l ight t ra i l ing

dece lera tor data.

be gathered to es t imate s ta t ic stabil i ty and damping

coefficient derivatives fo r u s e with the dynamic s t a -

bil i ty analyses of t ra i l ing dece lera tor configurations.

More complete information should

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I I I

G E R - l 2 8 4 2 A , VOL I

LIST O F SYMBOLS FOR APPENDIX C

A = r e fe rence a r e a

Cl = rolling moment coefficient

Cp = rolling moment coefficient der i p velocity (damping in ro l l )

Cm = pitching moment coefficient

ati e vith rolling

= pitching moment coefficient derivative with pitch- m C q ing velocity

= pitching moment coefficient derivative with angle of a at tack (X-body axis) m C

= pitching moment coefficient derivative with angle of m - C LY at tack r a t e

= pitching moment coefficient derivative with total angle m C p of at tack

CN = norma l f o r c e coefficient derivative with pitch r a t e

9

C = n o r m a l force coefficient derivative with angle of a t tack Na (X-body axis)

C = n o r m a l f o r c e coefficient derivative with angle of a t tack Nci r a t e

C = n o r m a l force coefficient derivative with total angle of N P a t tack

C = yawing moment coefficient n

C = yawing moment coefficient derivative with angle of yaw "0

Cx = axial force coefficient

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LIST O F SYMBOLS FOR APPENDIX C GER-12842A’ VOL I

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~

Cy = s ide fo rce coefficient

Cy = s ide- force coefficient der ivat ive with angle of yaw

P Cz = ver t i ca l fo rce coefficient

d = r e fe rence d i ame te r

D = s y s t e m re fe rence d i ame te r V

F = axial aerodynamic fo rce along X-body axis X

F = side aerodynamic fo rce along Y-body axis Y

F = ver t ica l aerodynamic f o r c e along Z-body axis Z

= ea r th grav i ty ge

I = moment of iner t ia about X-body axis

I = moment of iner t ia about Y-body axis

X

Y

I = moment of iner t ia about Z-body axis Z

k = t r a n s v e r s e radius of gyration

m = s y s t e m mass

M = aerodynamic moment about X-body axis X

M = aerodynamic moment about Y-body axis Y

M = aerodynamic moment about Z-body axis Z

= t o t a l ( rms) gravi ty load f ac to r Ntot

N.. = axia l g rav i ty load fac tor due to l i nea r acce lera t ion along X-body ax i s and cent r i fuga l acce le ra t ion due t o pitching and yawing angular veloci t ies

x’ q’

I I I I I I I I I I I 1 I 1 I 1 1 1 I

LIST O F SYMBOLS FOR APPENDIX C GER-l2842A, VOL 1

N.. Y,

= t r ansve r se gravity load f ac to r due to l inear acce l - erat ions along Y and Z body ax is and pitching and yawing angular accelerat ions

Z , i , i

p = rolling angular velocity

= rolling angular acce lera t ion

q = pitching angular velocity

= dynamic p res su re

6 = pitching angular accelerat ion

r = yawing angular velocity

G = yawing angular accelerat ion

V = velocity (total)

k = l inear velocity component along X-body axis

x = l inear accelerat ion along X-body axis ..

9 = l inear velocity component along Y-body axis .. y = l inear acceleration along Y-body axis

= l inear velocity component along Z-body axis

.. z = l inear accelerat ion along Z-body axis

CY = angle of attack

& = angle of attack ra te

p = angle of yaw

j = angle of yaw ra t e

AX = center of p re s su re position with respec t to sys tem ‘P center of gravity

= summation of re la ted fac tors or t e r m s

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