The four solid rocket booster (SRB) hold-down posts are fastened to the mobile launch platform (MLP) with four large nuts. At liftoff the nuts are split with explosive changes to release the SRB/Shuttle. A blast container is placed over the nuts to protect the vehicle from flying debris. The blast container is a reusable part and has to be protected from aerodynamic heating during flight. The thermal protection system (TPS) used to protect these blast containers is cork. Fitting the flat cork sheet to this hemispherical shaped blast container is both time consuming and expensive. Another problem is removing the charred cork and epoxy glue from the blast containers. Replacements of this cork with another TPS material such as MTA-2 was examined. Heating rates along the centerline of the forward facing areas of the blast container were determined. The feasibility of using 1/2 in. MTA-2 on the SRB blast containers for protection from ascent, plume impingement and reentry heating is demonstrated

Dean, W. G.

English

NASA Technical Reports Server

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TECHNICAL NOTE 
Huntsville Research 8 Engineering Center 
Contract ~ l \ s t j - 1 \ 2 ~ !  Date 30 June 1982 DOC. LMSC-HKLC TN D867571 
Title RESULTS OF TESTS OF MTA-2 T P S  ON THE SRB H@LD-DOWN BOLT BLAST CONTAINER 
-c 
BACKGROUND 
The SRB s i t -  on t h e  MLP b e f o r e  launch on f o u r  hold-down p o s t s .  These 
f o u r  hold-down p o s t s  are f a s t e n e d  to  t h e  HLP w i t h  f o u r  large n u t s .  
t h e s e  n u t s  are s p l i t  wi th  e x p l o s i v e  charges  t o  release t h e  SRB/Shuttle. 
" b l a s t  c o n t a i n e r "  i s  placed over  t h e s e  n u t s  t o  p r o t e c t  t h e  v e h i c l e  from f l y i n g  
d e b r i s .  T h i s  b l a s t  c o n t a i n e r  i s  a r e u s a b l e  p a r t  and h a s  t o  be p r o t e c t e d  from 
aerodynamic h e a t i n g  d u r i n g  f l i g h t .  P r e s e n t l y ,  t h e  TPS used t o  p r o t e c t  t h e s e  
b l a s t  c o n t a i n e r s  i s  cork. F i t t i n g  t h e  f l a t  cork  s h e e t  t o  t h i s  h e m i s p h e r i c a l  
shaped b l a s t  c o n t a i n e r  i s  both time consuming and expensive.  
i s  removing t h e  char red  cork and epoxy g l u e  from t h e  b l a s t  c o n t a i n e r s .  
t h e r e f o r e  d e s i r a b l e  t o  r e p l a c e  t h i s  cork  wi th  a n o t h e r  TPS material such as 
MTA-2. 
A t  l i f t o f f  
A 
Another problem 
I t  i s  
OBJECTIVE 
The purpose of t h e  tests p r e s e n t e d  h e r e i n  i s  t o  demonst ra te  t h e  f e a s i -  
b i l i t y  of u s i n g  112 i.1. MTA-2 on t h e  SRB b l a s t  c o n t a i n e r 8  f o r  p r o t e c t i o n  from 
a s c e n t ,  plume impingement and r e e n t r y  hea t ing .  
TEST DESCRIPTION 
C a l i b r a t i o n  Runs: A c a l i b r a t i o n  model was f a b r i c a t e d  and run i n  p o s i t i o n  1 of  
t h e  
t h e  
NASA-MSFC Hot Gas F a c i l i t y  (HGF). 
The purpose of t h i s  m o d e l / t e s t  was t o  de te rmine  t h e  h e a t i n g  rates a l o n g  
c e n t e r l i n e  of t h e  forward f a c i n g  a r e a  of  t h e  b l a s t  c o n t a i n e r .  The model 
f a b r i c a t e d  U I - ,  "spare" b l a s t  c o n t a i n e r  
ASA-CR-17C891) RBSULTS OF TESTS OP BTA-2 
TPS ON THZ SBB HOLD-DOWN BOLT BLAST 
CONTAINBB (Lockheed Hissiles and Space  Co.) 
13 p HC A@2/HP A S 1  ZSCL 21tr 
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CENTER 
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https://ntrs.nasa.gov/search.jsp?R=19850026911 2020-03-20T17:16:08+00:00Z
UlSC-HREC TN D867571 
The m o d e l  i s  roughly a hemisphere w i t h  about  10 i n .  d iameter  and approximately 
7 in .  high. 
10 thermocouples and f a s t e n e d  t o  t h e  o u t s i d e  s u r f a c e  o f  t h e  m o d e l .  
t h i c k ,  3f4-in. wide,  cork  s t r i p s  were placed under t h i s  s t a i n l e s s  steel  s t r i p  
wi th  about  a 1/2-in. gap between them to  form a n  a i r  c a v i t y  behind t h e  
thermocoaples.  
t h e  approximate l o c a t i o n s  of t h e s e  thermocouple locat ions.  
model was recessed i n t o  t h e  HGF "f loor"  by about  3/4 in .  t o  h e l p  prevent  
chocking of  t h e  flow. 
A " t h i n  shin" s t r i p  of  304 s t a i n l e s s  steel  was ins t rumented  wi th  
Two 1/8 i n  
F igure  1 is a photo  of t h i s  completed model. S k e t d i  1 shows 
The hemisphere 
This  model was run f o r  :wo 5 sec runs  i n  p o s i t i o n  1 of  t h e  HGF. R e s u l t s  
The i n  t h e  form o f  h e a t i n g  rates a t  each TC l o c a t i o n  are shown i n  Table  1. 
maximum h e a t i n g  rate o f  approximately 80 B t u f f t  -sec occurred  a t  l o c a t i o n  
2. Table 1 Slso p r e s e n t s  t h e  r u n  c o n d i t i o n s  and t h i n  s k i n  material prop- 
e r t ies  used t o  reduce t h e  d a t a .  
s k i n ,  temperatwe-t ime s l o p e  method. 
2 
The data were reduced u s i n g  t h e  s t a n d a r d  t h i n  
Data from t h e  second run were n o t  used because t h e  cork  s t r i p s  c h a r r e d  
and allowed flow under  t h e  t h i n  s k i n  s t a i n l e s s  steel s t r i p .  
TPS Test :  
nominal 1f2-in. t h i c k n e s s  of MTA-2. The b a s i c  hemisphere was f i r s t  sand- 
b l a s t e d  and then  primed and p a i n t e d  b e f o r e  t r o w c l l i n g  t h e  MTA-2 i n  p lace .  
MTA-2 was then cured  o v e r n i g h t  i n  a n  oven. 
t h e  MSFC Materials Lab.) 
Five thermocouples were used t o  moni tor  t h e  i n s i d e  s u r f a c e  tempera ture  o f  t h e  
b l a s t  c o n t a i n e r  d u r i n g  thP 
2. 
purposes. 
A f t e r  t h e s e  c a i  tests, t h e  model was r e f u r b i s h e d  and covered wi th  a 
The 
(This  TPS was a p p l i e d  in-house a t  
A photo of t h i s  f i n i s h e d  model i s  shown i n  Fig.  2. 
?st ,  t h e  l o c a t i o n s  of  which are shown i n  s k e t c h  
A maximum a l l o w b l e  tempera ture  of  400 F on any TC was s e l e c t e d  f o r  c u t o f f  
The pun time f o r  t h i s  TPS model was s e l e c t e d  as fol lows.  
2 
The plume i m -  
pingerr.ent h e a t  load of  278  B t u f f t  
M-9230-76-60 from W. Youngblood t o  D. Seymour, f o r  a n  X l o c a t i o n  of 1870 i n . ,  
was obta ined  from Northrop document No. 
2 
LOCKHEED-HUNTSVILLE RESEARCH 6 ENGINEERING CENTER 
LMSC-tlpEC TN D867571 
2 and a 8 = 30 deg. 
was ob ta ined  from t h e  October 1980, Design Environment for Body P o i n t  2186 f o r  
a s c e n t  and 7037 f o r  r e e n t r y .  
An o v e r - t e s t  f a c t o r  o f  40% was used t c  g i v e  a to ta l  h e a t  l oad  r e q u i r e d  of 1106 
B t u / f t 2 .  
t i m e  would be 13.9 sec .  
The combined a s c e n t  and reo,ntry h e a t  load of 512 B t u / f t  
T h i s  gave a t o t a l  heat load o f  790 Btu / f t2 .  
2 With a peak h e a t i n g  ra te  of 79.6 B t u / f t  sec t h e  r e q u i r e d  test 
This  TPS model was run on 4 June  1982 (Run 1166) i n  p o s i t i o n  1 of  t h e  
HGF. The t e s t  r a n  for 13.4 sec a t  which t i m e  i t  was  t e rmina ted  wben TC 1 
exceeded 400 F. F igure  3 shows t h e  p o s t - t e s t  photo  of t h i s  model. R e s u l t s  of 
t h i s  test are shown i n  terms o f  pretest and p o s t - t e s t  t h i c k n e s s e s ,  r e c e s s i o n  
and r e c e s s i o n  rates a t  each l o c a t i o n  i n  Table  2. Since  t h e  m o d e l  s u r f a c e  is  
curved,  two measurements were made a t  each l o c a t i o n  - one p e r p e n d i c u l a r  t o  t h e  
c e n t e r l i n e  and one p a r a l l e l  t o  t h e  c e n t e r l i n e .  
l o c a t i o n s  ( 3  and 4 ) .  
a t t a c h e d  t o  t h e  model and were t h e r e f o r e  n o t  t y p i c a l  o f  t h e  f l i g h t  envi ron-  
ments on t h e  b l a s t  c o n t a i n e r .  The f i r s t  two p o i n t s  ( 1  and 2 )  were probably i n  
a s e p a r a t e d  f low reg ion  - a g a i n  probably  n o t  t y p i c a l  of t h e  f l i g h t  environ- 
ments. It was t h e r e f o r e  dec ided  t c  exc lude  t h e s e  f o u r  p o i n t s  from t h e  
a n a l y s i s .  
The TPS burned through a t  two 
These were i n  the area where t h e  flow probably  re- 
F igure  4 shows a p l o t  o f  r e c e s s i o n  rate v e r s u s  h e a t i n g  ra te  from t h i s  
test .  
least  s q u a r e s  method. 
q1*154. 
s t anda rd  MTA-2 thermal p r o p e r t i e s  from prev ious  a n a l y s e s .  An a n a l y s i s  was 
performed f o r  a p o i n t  on t h e  v e h i c l e  nea r  t h e  " h o t t e s t "  t h r u s t  p o s t / b l a s t  
c o n t a i n e r  l o c a t i o n .  
a s c e n t  body po in t  679, and r e e n t r y  body p o i n t  7412. 
p o i n t  f o r  r e e n t r y  i s  7105). 
+Y a x i s  on t h e  l e f t  hand SRB, as seen  on Fig.  5. 
from a p o i n t  a t  X = 1870 i n .  0 = 30 deg from Northrop document No. 
M-9230-76-60 from W. Youngblood t o  D. Seymour. The t o t a l  h e a t  l o a d s  from 
A s t r a i g h t  l i n e  was p u t  through t h e s e  d a t a  by "eyebal l "  - n o t  by t h e  
The e q u a t i o n  o f  t h i s  l i n e  w a s  found t o  be R = 0.33 
This  e q u a t i o n  was i n p u t  t o  t h e  Lockheed a b l a t i o n  program u s i n g  
The  October 1980 Design Environments were a p p l i e d  f o r  
(The e q u i v a l e n t  body 
These p o i n t s  are a t  30 deg from the  +Z toward t h e  
Plume h e a t i n g  was a p p l i e d  
3 
LOCKHEED-HUNTSVILLE RESEARCH 6 ENGINEERING CENTER 
LMSC-HREC TN D867571 
2 2 as  compared t o  t h e  790 B t u / f t  t h e s e  p o i n t s  added up t o  804 B t u / f t  
o r i g i n a l l y  planned f o r  t h e  HGF tes t  model. 
The computer program c a l c u l a t e d  temperature  and r e c e s s i o n  f o r  t h e s e  con- 
d i t i o n s ,  u s i n g  a 112 i n .  t h i c k n e s s  of MTA-2. A t  t h e  end of t h e  t r a j e c t o r y  
(410 sec) ,  t h e  MTA-2 had receded 0.28 i n .  and t h e  max imum tempera ture  on t h e  
b l a s t  c o n t a i n e r  was 157 F. Therefore  t h i s  112 i n .  t h i c k n e s s  g i v e s  a 1.78 
overdes ign  margin. 
CONCLUSIONS 
A s  a r e s u l t  o f  t h e s e  tests and a n a l y s e s  i t  is concluded t h a t  t h e  0.5 i n .  
MTA-2 i s  adequate  f o r  t h e  b l a s t  c o n t a i n e r  on t h e  SRB f l i g h t  v e h i c l e .  
C o n t r a c t  NAS8-32982 
Approved : 
Systems Engineer ing  Sec t ion  
Attach:  (1) Tables  1 and 2 
(2)  Figs .  1 through 5 
4 
LOCKHEED-HUNTSVILLE RESEARCH 6 ENGINEERING CENTER 
LMSC-HREC TN D867571 
Table 1 
CALIBRATIOIJ TEST RESULTS 
(Run f1160) 
Surface from 3ase of 
Model (In.)  
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
1.0 
2.0 
3.0 
4.0 
5.0 
6.0 
7.0 
8.0  
9.0 
10.0 
~~-~ ~~ 
Cold Wall 
Heating Rate 
2 (Btu/f t -sec) 
78.2 
79.6 
61.4 
38.7 
37.7 
24.0 
Bad 
11.6 
21.9 
Bad 
Notes : 
1. Thin-skin wall  thickness = ,0295 in .  
2. Thin-skin w a l l  material = 304 stainless steel 
3. Thin-skin wall  properties [p  C t ]  = .126 
4 .  Run conditions: 
P 
Pc = 138 psia,  Tc = 1600 F ,  
Pair = 135C ps ig ,  PGH = 900 psig 
2 
5 
LOCKHEED-HUNTSVI T. LE RESEARCH 6 E N G I N E E R I N G  CENTER 
LMSC-HREC TN D867571 
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L n d O N O c J u a b m  
m m r l d b b b h o d  m u u u r n d o o d d  . . . . . . . . . .  
. .  . . . . . .  
o u  r l a o o u a m  
d h l o o u d N m u m  
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LOCKHEED-HUNTSVILLE RESEARCH 6 E N G I N E E R I N G  CENTER 



LMSC-HREC TN D867571 
. 2 Cold Wall Heating Rate, q (Btu / f t  - sec) 
Fig. 4 - Recession Rate vs Heating Rate for MTA-2 on Blast Container 
10 
LOCKHEED - HUNTSVILLE RESEARCH 6 ENGINEFRINC CENTER 
D867571 
Location of Hold- 
Down Blast Container 
+ 
Fig. 5 - Left-Hand SRB Aft Skir t  
11 
LOCKHEED. HUNTSVILLE RESEARCH 6 ENGINEFHiNG CENTER 
LMSC-HREC TN D867571 
ORSG~NAL PAGE rs 
OF POOR QUALITY 
( N u t  t o  scale) 
Y 
3 / 4  in. recess 
in panel r f - - - h  
Side V i e w  
Sketch 1 - Approximate Thermocouple Location and Thickness Measurement 
Locations on Calibration Model BL-CONT-CAL, Run No. 1160 
12 
LOCKHEED - HUNTSVILLE RESEARCH 6 ENGlNECRlNG CtNTER 
LMSC-HREC TN D867571 
(Not to  Scale) 
I \ 
\ 
Note: Dimensions are approximate 
and along surface of blast 
cmtainer.  
/ 
I I 
t x - x  % 
4.5" i 
1+3.5'+ t- 3.5" 4 
L -  
Front V i e w  
Sketch 2 - Thermocouple Locations on TPS Model - BCA-1 
1 3  
LOCKHELD. HUNTSVILLE RESEARCH b ENGIN€FRiNG CCNTER 


Results of tests of MTA-2 TPS on the SRB hold-down bolt blast container

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