ENGI NE PROG RAM OFFI CE SATURN HISTORY DOCUMENT University of Alebema Research Institute Hiet~ry f: Science G. Technology Groilp Date -------- -- Doc. No . ----, , , DEVELOPMENT OF LOX-YYDROGEN ENGI NES FOR T HE SATURN APOLLO LAUNCH VEHICLES NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
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8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
Developxnent Pr og ra mFig ure 5 shows the~deve lopm'enf yc le for the
RL -1 0 engin e v..llich f all s within the typi cal 5-7
ye a r spa n re qu i re d fo r p ropu ls ion sys te ms .
Tes t ing under s imula ted Centaur s ta ge condi-
t ions on a dua l-pos it ion ver t i ca l tes t s tand contr i -
buted significantly to the lack of engine pro ble ms
once vehicle ground and flight testing commenced.
Vehicle components such as the hydraulic po wer
pack, propellant utilization drive moto r, r e c i r c u l -
ation ducts and diffuse rs, vehicle boost pumps,
and re tromaneuver discharge duc ts were tes ted
on the dual-engine stand under conditions closely
approximating those found on the actua l s tage in
flight. Thi s not only allowed inter action s on th eengines to be identified, but permitted accurate
simulation data for purpo ses of developing the sta ge
components.
Produc t ion support e f for t was ini t ia ted to min-
imi ze the impact of production probl ems and con -
t inua l ly impro ve s ys tem re l iabi l i ty and f l ight .wort hiness . This included establishment of vehi-
c le s ta r t ing sequences and l imits , opt imizat ion
of prelaun ch chilldown and boost pump sett ing s,
and investigation of flight problems.
Basic technology was developed in speci al te st
fac i l i t ies , hydrogen injec tors , ignit idn sys t ems ,
idling and throttling, reduced net positive suction
head (NPSH) operation, the use of cryogen ics for
a bearing and ge ar coolant and the feasibility for
a "zero chilldo\vn time" engine.
The RL-10 has not only been a reliab le engine
sys tem for the Sa turn and Centaur program s, but
has se r ved as a " tes t-bed" for other a reas of
technology. The use of fluorine a s a11,oxidizer was
pro ven on modi fied engin es of an ea;G_vintage to
provide one of the f i rs t " fl ight we i~ ht " luor ine- -prototjrpe engines. This w as arcolnplislled by mod-.
ifying the pump seals in the oxidizer system to pro-
vide fluorine compatibility and by changing the
engine "trim".
A modified RL-10 engine has run successf ully
in the throttling mode down to one percent of the
ra ted engine thrus t . The feed sys tem was s table
a t a l l thrus t leve ls in this range . F u r t h e r , a
modified RL-10 has operated in the low-idle mode,
in which the turbopump does not r otate b ut the. . . . .
2; ..--- ---& engine ope ra te s on tank pre ssur e with gaseous ,cCall U a j . E ~ liquid. o r mixed-phase
Other areas. , such as hypergolic ignition through
the use of a small perc entage of trioxygen difluoride
in the oxidizer and ins tant-s ta r t or ze ro cooldownF i g u r e 5. RL-10 Projec t Miles tones tim e accomplished by insulating the fuel pump in -
te rna l surfaces , were inves t igated us ing the RL-10The f i rs t Centau r f l ight ut i l izing an RL-10 engine as a l~ te s t -bc d~ lnd were pro,7en feasible.oc cur red fix-e ye ar s a f te r pro gram init iat ion. Ap- r:
proxilna te ly $240 mil l ion do l la rs was spent on the , Problems
RL-10 engine program of whicll about seventyThe RL - 10 engine encountered-a wide galnut of
pe rc ent \-:as sp en t on the developnlent phase. probl ems during development. Some of the majo r
.. pro6lem a re as a re l is ted below. .'
T he e ng ine , in i t s va r ious v e r s ions ha s c om- (1 thrus t over shootpleted 01 e r o ne nill lion seconds of total firin gs; ( 2 ) gimbal block lubrication -and has been flown on 15 Centaur flights and six - ( 3 ) spark igniter deficiencySaturn f l rghts. A total of 66 engines have been -
flo\i.n with n o malfunction which affected the m is -
sion. b
3 ;
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
. Th rus t Overshoot. The Cent aur vehicle wa s Gimbal Block Lubrication. The gimbal ass em -
unable to accept m or e than 15 perc ent th r us t over - bly is the componen.t with the highest unit loading
shoot. Th rus t exceeding the specif ied l imi t oc-
cu r r e d b ecau s e th e en gin e th ru s t co nt ro l v a lv e
( F i g u r e 6) was s e t t o ma in ta in a ch amb er p r e s s u re
of 300 ps i and d id not by-pass any turb ine dr iv e
g as u n ti l t h e n o min a l th ru s t l ev e l was reached.
T h e s y s t e m m o m en t um w a s n o t r e t a r d e d e a r l y
enough to prev ent the overshoot . Adjus tments ins p r i n g p r e s s u re o n the th ru s t co n t ro l p i s ton p r e -
vented exces s ive th rus t overshoot , bu t caused the
sys tem to s tab i l ize below the nominal th rus t level .
The problem w as so l ved by the incorpora t ion
of a "pneumat ic r ese t" on the th rus t contro l . Th e
th ru s t co n t ro l b y -p a ss w a s s e t t o op en a t a l o we r
ch amb er p r e s s u r e ( ap p ro xima tely 270 ps i) , and the
d es i r ed n o mina l 3 00 p s i ch amb er p r e s s u re was r e -
es tab l is hed by use of the pneumat ic re se t sys tem.
' The referen ce pr es su re on the back s ide of the
th ru s t co n t ro l b y -p as s p i sto n i s a tmo s p h e r i c p r e s -
s u r e wh ich i s e s s en t i a l ly ze ro p s i a t t he en g in e
opera t ing a l t itude . When the thrus t contro l ler by-
p as s i s ac tu a ted a t th e lo wer ch amb er p r e s s u re
leve l, hydrogen is vented into the thru st control
body. By orif icing the thrus t cont rol valve body
vent , the body pr es su re and p is ton ref eren ce pres -
s u r e a r e in c r eas ed ap p ro x ima te ly 3 0 p s i which r e -
s e t s the by-pass re l ief p re ss ur e to ob ta in the nom-- -
* - , . ,i n a l 300 p s i ch amb er p r e s s u r e . ,By this method
the r ' ese i p ressure lags the body dur'ing
engine accele ratio n \vhich allows the thrust contro l
valvd to reLurn to a nominal pos ition before thc de-
s i r ed 3 00 p s i ch a tn b e r p r e s s u r e i s r each ed .
Development of a backup elec tro3i c thru st con-
t ro l le r was in i t ia ted in the product ioh s uppor t p ro-
gr am and the des ign had prog ress ed to the po int
whe re a de cis ion could have been made to use i t
when the modified pneuma tic con trol ler proved
s , a t i s f a c t o r y ..h * - - - =7
i.~ & u r c 6 . Th rus t Contro l Valve Schemat ic,z.%, *. -
aid is the only loaded compo nent that i s exposed to
high vacuum during engine operation. Space vac-
uum effect on mat eria ls is s ignificant in two
r e ~ ~ e c t s .
(1 ) evaporat ion of solid s
(2) vaporization of surf ace gas lay ers
1Evaporation of mat eria l is not a significknt pro-
blem because of t1le rate of m ater ial los s i s negli-
gible at te mpe ratu res below 300°F and the engine
surface temperatures remain continuously below .this crit ical range. Vaporization of surf ace gas .lay ers of engine components is a s ignificant pro-
bl em beca use of the assoc iate d phenomenon of "cold
welding. " Degass ing a meta l sur face removes the
oxide coat ing that i s characte r is t ica l ly presen t
within the atmos pher e of the earth and pro te cts the
me ta l s u r f ace ag a ins t ~n o lec u la r t t r ac t io n of s imi -
la r c lean mater ia ls . Also the f r ic t ion behveen the
rubbing metals increases proportionately to the ex-
ten t tha t the sur fa ces a re degassed . A d ry f i lm
lubr ican t (molybdenum disulphide) was developed
fo r the gimbal block to reduce the increas ed torque
encounte red under sp ace conditions to a tolerable
leve l well within the s t ruct ural capabili ty of the
engine and the vehicle.
Spa rk Igniter Deficiency. The f i r s t s t a t i c t e s t
s tan ds ' t hat were buiIi for the R L - 10 development
pro gra m positioned the engines in a horizontal att i-
tude for firing into a long diffuser. The d i f fusers
wer e used to cre ate a vacuum around the engine
pr i or to s tar t . Late r a dual engine tes t s tand was
'built in.wh?eh.the engines w er e positioned verti-
cally and f ired downward into diffusers fr om a n
elevated facili ty. The f i r s t a t tempt to f i re an
RL-10 engine vertical ly resulte d in an explosion
that extens ively d lmaged the engine and tes t facil-
itie s. .The ensuing investigation prov ed that LO X
was introduced intd the thrus t chamb er in suc h a
way that i t bypassed the igniter. During the s t ar tof a horizontal engine fir ing , the LOX fo rmed a
pool inside the thru st chamb er. Boil-off f rom this
pool mixed with the hydrogen to fo rm a com bus -
tible mix tur e fo r ignition. When the engine wafi
f ire d verticall y, the LO X droppsd to-the bottom of. L -
the diffuser tubes, and the ignition occ urr ed at that
point. The explosion pro gre ss ed up through the
diff user s to the engines and test facili ty. The cn-
gine inje ctor was modified s o that both oxygen and
fuel wer e rou ted pas t a rece ssed spa rk- torch ign i-
ter dur ing s t ar t and so lved the problem.
Up ra ti'ng
There has been a sus ta ined spectacular payloadincr ease over thc years att r ibuted to engine im-
provement . A s s h o v ~ n d F i g u r e 7, an increase of
a l m o s t 800 ' Ibs.of payload has re sult ed from engine
improvements made over a s ix ycar period: Es s en -
t ia l ly a l l of these amel iora t ion s resu l ted f rom i tn-
pro vem en ts i:l efficienc y with the IS P progressing
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
* - s te p -wise f ro m the o r ig ina l de s ign spe c i f ic a - Design f lexibi l i ty had to be mainta ined s i nce
t ion l im i t of 412 lb. s e c i lb to a deliwered the J -2 engine was to be used in the second s tage
no ~ni na l f 442 lb s e c l lb . of the Sa tu rn IB a nd the s e cond a nd th i rd s ta ge s
of the Saturn '7 , a s shown in F igure s 8 and 9.
----RLIOA-I SPEC YL\ rSP. i 12 SEE . EL OX< SSP
F i g u r e 7. RL-10 Engine Contr ibut ion to Centaur
P a y l o a d I n c r e a s e
F i g u r e 8. Satu rn IB-V, Engineis-IVB StageAc c ompl i shme nts
Application. Som e of the accompli shments of the RL-10
e n gi n e p r o g r a m a r e l i s t e d b e lo w:(1 ) First LH2/LOX engine
r- --- --- -- -- --- - I- -2.. -- - .".(2) Develope d LH2 techfiology -- -- - - '1- -(3 ) Combustion Stabi l i t y ! I; F I V E 1- 2 IhCINfS OH 5-11 STLCL
PROPELLAW1(4 ) Mult ip le s ta r t c a pa b i l i ty -
1 .' F i LOI/LH2/ , 0111 l"R"l,(5 ) Idl ing and throt t l ing capabil i ty ! .--%&/...-
1I
~. lzs.ooo 0;I
(6 ) Test-bed for oth er a re as of technology i- 1 : 1.!50.OGO LB
" 3 - 3 , ,- ": ',
LAa gL<_;' . . . .< gg - - -,
T h e RL -10 e ng ine ha s be c ome a work-h orse in9-
the pr .op1s ion f ield . In addit ion to b e i n g a n e x - + I : -. - . l-. - 5 " - ,I- -c e l le n t experimental tool it a l so wa s the fo re -
/. 5 - <.,{'
;7 * :;,-5 . <>run ner of the J -2 and M -1 engines. ' \ ,
, \.-I
- 'Iy-.
I ;..-r, --..- % -l, .. .rP a r t 11: Development of the J-2 Engine ,? . -
*. ." 7 ,. -
Design ~ h i l o s o ~ 1 1 ~ \ * ~ ~ H ! C L Efi.:?, n!r~,.sg2 < .'4- ,;1
- I r/\
&I\T "'ktf!1cLE S:-S'i4 E i ' D S U J S f ~ f i i T zz f 1
T he J -2 e ngine i s the s e c ond ma j or p ropu lsion - -& I
sys te m de ve loped us ing l iqu id hydroge n a s the fuel .F i g u r e 9. Sa tu rn V, Engine/S-LT St age .Applicati on
Developm ent of the 5-2 engine was under take n to
5ati sfy the need for a high -thru st, high-perforlPn-
anc e upper s tage engine which would be capable of I t was dec ided in the ear ly s tages of the Apollo
,r e $ & r t i w in, pace. Prdpe l lant ut i r iza t ion and Pr og ra m tha t the engines for the second and
t h ru s t ~ r o g r a m ~ n i n ge qu i r e d a n a dd i t iona l f l e x i - third s tages would be comple te ly inte rchangeable .
bi l i ty fo r the engine sys tem., Much of the exper- The J -2 engine requi res only minor changes to
iec ce and technology ga ined on the RL-10 P rog ram per mi t appl ica t ion in the second and thir d s tag es .wa s d i r e c t ly a pp l ic ab le to the J -2 e ngine. Since Changes in the insulation, orificing, and he a t e x -
the J - 2 wa s to be used on a manned vehic le . cons id- changer connect ions a re required, and provis ions
erab le a t tent ion had to be given to achieving a high mus t be ma de fo r r e f i l ling the hydroge n s ta r t bo t t le
re l iab i l i ty through ex tens ive component and engine fpr the S-IVB res ta r t .
sy s t em s ground tes t ing to reso lve a riy potent ia l
pro ble ms before f l ight tes t ing. In the des ign of
the 5-2, a t tea t ion has been focused on potent ia lDescr ipt ion
fa i lu re 111odes and inhere? t des ign ch ar ac t e r is t i cs The J -2 rocke t engine , shown in Figu re 10,
whic h c ou ld p re ye n t the se f a i lu re s ; - Welded joints i s a 230 , 000-pound th rus t , mul t ip le - re s ta r t ,
a r e used throughout the engine to prevent leaks . gimballed engine utiliz ing liquid hydrogen and
D ua l s e a l s , w it h i ~ l t e r m e d i a t e l e ed s , a r e us e d
- a t a l l h ot g a s and prope l lant separable connec t ions .
1
5
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
' ' . l iq u i d o x y ge n a s p r o p e l l a n t s a n d is d e s i g n ed t o b e
u s e d s i n g u l a r l y o r c l u s t e r e d . T h e e n g i n e h a s a
r e g c n e r a t i v e l y c o o l e d t h r u s t c h a m b e r , . s e p a r a t e
LHZ a n d LO X p u m p s d r i v e n b y a g a s g e n e r a t o r
c o ~ e c t e dn s e r i e s t o t u r b in e s p ow e ri n g e a c h
p u m p , g a s e o u s h y d r o g e n f o r e n g i n e s t a r t , a n d a n
i n t e g r a l h e l i u m c o n t r o l b o t t l e f o r p n e u m a t i c v a l v e
o p e r a t i o n . An e l e c t r i c a l c o n t r o l a s s e m b l y ( E CA )
p a c k a g e c o n t r o l s t h e e d g i n e s e q u e n c i n g a n d p r o -
v i d e s t h e h i g h v o l t a g e t r a n s f o r m e r s f o r t h e s p a r k
ign i t ion sys t em.
C
T h e m a j o r p a r a m e t e r s a r e s ho wn i n F i g u r e 11.
fo r f l i gh t eng ines . Bo th the f i r s t f l i gh t conf igu ra-
t ion and !he uprate d configurat ion eng ine s have
been qual i f ied . T h e f li g h t t e s t p r o g r a m t o c s t a b -
l i s h o v e r a l l v e h ic l e p e r f o r m a n q e h a s v e r i f ie d t h e
eng in e ' s f l i gh t capab i l i t i es . The 5 -2 eng ine has
b e e n u n d e r d e v e l o p m e n t f o r a l m o s t e i g h t y e a r s .
E x t e n s i v e c o m p o n e n t a n d s y s t e m t c s t in g h a v e
d e m o n s t r a t e d a re l i ab i l i t y of 0 .9950 a t a 50 pcrc cn t .
conf idence l eve l . T h e r e h a v e b e en 3 , 1 8 3 s ing lc -
e n g i n e t e s t s w i t h a n a c c u m u l a t e d t e s t t i m e o f
309 ,140 seconds . T h e r e h a v e b e e n 57 c l u s t e r f i r -
ing t es t s , cons i s t ing of the fu l l f ive-engine c lus -
t e red conf igu ra t ion c o n d u c t ed f o r 1 0 , 1 1 3 s e c o n d s
of f i r ing t ime . T h e J - 2 e n g in e h a s m a d e f o u r
S a t b r n IB f l igh t s and two f l igh t s in t he Sa tu rn V
vehicle.I I~ k u r e2. J -2 E n g in e P r o j e c t M i l e s t o n e s
F i g u r e 10 . 3-2 Engine
Prob lc lns (Non-Fl igh t ) . Th e c o u r s e of t h e J - 2
, devclopment has no t been wi thou t inc iden ts . The
f i r s t en gi ne t e s ~ s x h i bi t ed s i d e l o a d s d u r i n g s t a r t
-a t s e a l e v e l c o n d it io n s ; h o w ev e r , t h e r e h a v e b e e n
. . .
.... .... no s i de load p rob lem s whi l e t cs ti r ig a t a l ti t ude ......
.... .. T h e s i d e l o a d s w e r e d u e t o g a s fl ow s e p a r a t i o n s... . .> L "..., ..,.. i n s i d e th c t h r u s t c h a m b e r . S ince the g imbal ac tua -
.......,.. ...... t o r s w e r e d es i g n e d t o ta k e t h e n o r m a l t h r u s t l o ad ,........ ...-.,. ... .
. . me an s had to be found to con ta in these s id e.. .,. = .~ . l oads . Th i s was accompl i s hed bv modi fy ing the....... .....*.-. with the 'addi t ion of s ide Load r es t r ai n-,- ......
,............ i ng a r m s t o p h y si c al l y h ol d t he e ng i ne d ~ r i n gn -,.,.....: ... .--- -- -............ --
g i n e s t a r t .~ . . ~............
".. .............
. . . . F u e l p u m p s t a l l w a s a d e v e l o p m e n t p r o b l e m.......
: , , .".. e a r l y i n th e p r o g r a n i , The . fue l pump 'f low e n te red .
. . . . . . . . . . . . . .' . > ,. %....*a - I L ..---L- - . .. - . -.., .. h e r e g e n e r a t i v e l y c o o le d j a ck e t b e f o r e p a s s i n g
' in to the in jector . A s t h e fu c l pu m p d e l i v e r e d t h e
F i g u r e 11 . 5 - 2 E n g in e P a r a m e t e r s f i r s t f u el t o t he r e l a t i v e l y w ar n -, c h a m b e r , a c o n -
s i d e r a b l e v o l u m e of h y d r o g e n g a s w a s c r e a t e d . The
D e\ e l o p ~ n e n t r o g r a m g a s c o u l d no t p a s s t h r o u g h t he i n j e c t o r a t a r a t eSign l i t c an t deve lopm ent s wi th ,in th e 3-2 p r o - suffi ,cient to kecp up with the flow. Thc soluLion was
g r a i n a r e s h o w n in F i g u r e 1 2. T h e d e v e l o p me n t . to p rech i l l t he pump and charnbcr .irith l i q u id h y d r o -
t c s t p r o g r a m h a s t h r e e d i s t in c t f a ce t s: C a m p o - g c n t o l i m i t t h e t e n l p e r a t u r e c o n d i t i o n s u n d r r w h ic h
n e n t t e s t i n g , e n g i n e s y s t c n l s t e s t i n g , a n d i l i g h t - a s t a r t w0u.l-d be atte mpt ed.
t es t ing . Th e compo nen t t e s ine, con s i s t s of qua li - .
fy ing a l l maj o r co1nponer ;t s and ver i f i ca t ion t es t ing%
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
around the ent ir e peripher y. Since this wheel Fig ure 18. F ai led ECA T i m e r T r a n s i s to r
opera ted a t about 8 ,000 rpm, the potentia l energy
avai lable could cause ca tas trophic re sul t s i n ca se This whisker growth is a c ha ra c t e r -of failure. It was disco vered that in going through isti c of noble bas e metals such as t in, indium,the mixture ra t io excurs ion on the J -2 engine, a read and s i lver . The growth i s known to be acc e l -standing wave was ge nera ted in the turbine wheel e ra t e d by (x-ray) , mois ture , e lec t r ica~cpoten2n-which continued to flex the metal a t the hub ar e a ial difference, and the pres ence of si l ica. Sinceunti l fat igue occu rred . BY changing the web thick- ' the t rans i s tor ha s a t in pla ted case , contains s i l i ca
ness and the st i ffening characterist ics of the wheel ge l de s i c c a n t is assembled in an uncontrol led hu-- -the destruct ive standing wave vibrat ion was el im- miditxen3,ironment, ha s a poor her me tic seal, and
--.----p..-p.
Enat&-- - -
- . i s exposed to an e lec t r ica l potentia l di f fe rence i t- .makes an exce l lent t es t -bed for whisker growth.
-
The re was concern over replac ing a qua li f ied com--, - 8 7 -2 -------- \ w - 7 -r-- -- ponent which had 2296 engine hot fi r e tes ts f or a
' ..._-- . fir-<
;>demo nstrated rel iabi l i ty of 0.9999 at a 50 perc ent
- -,/. --- , confidence level and 50,000 ex posure s in no=-hot../.a ,-- - . ~ . f i r e t e s t s f o r a rel iabi l i ty of 0. 9998 at a 50 per -.-.L:---'-1.
cent confidence level . Th is is another example
of the A pa lo prog ram pushing the s ta te of the a r t .
The t rans i s tors wer e the bes t ava i lable in the
indust ry a t the t ime they were chosen for the ap-
pl icat ion. However, th e long lead t im e involved .
in manufac turing an i t e m a s compl ica ted a s the
Saturn V vehicle resul ted in long s torage t im e fornumerous sub-components . This t ime per iod was
sufficiently long enough to allow the whisker to
grow to the extent tha t i t caused a short be tween
the t rans i s to r e lement and the case . The t r a ns i s -
to rs w ere rep laced with a high re l iabi l i ty improv ed
uni t made under mor e r igid manufac tur ing sp ec-'
Fi gure 17. LOX Tu rbine Wheel Hub Cra ckificat ions and with a c as e mater ial which did not
suppo rt whisker growth.
EC A T i me r Fa i l u re s . An e l e c t r i c a l c on t ro l
a s s e n ~ b l y imer fa i lure occu rred during checkout
at Cape Kennedy. Throughout the histo ry of the
t imer development encompassing about eight years
only 'e leven fai lu res were noted. Of these fai l ur es
s i x we re a t t r ibu t e d t o t r a ns i s t o r s i n t he amer c i r -
cui t . A thorough inves t iga t ion of th e p r o b j6 ~ i t -
t ributed th e caus e to be whisker growth wiF1Gn
the ca se enclosing it CI< 65 t rans i s tor w&+ is an '
integ ral pa rt of the t ime r. The urhisFer &.r?wthis shown in Figure 18. . .
P r ob l em s ( F l i g x .
AS-203 hot cro sso ve r duct. Fl ight data
f r o m AS-203 indica ted tha t the c ro ssov er duc t
(See Fig ure 10) which con nects the fuel turbin e
to'the oxidizer turbine did not cool a s rapid ly
as ant ic ipa ted and the addi tiona l energy in thesys tem inf luenced the engine s ta r t t rans ient .
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
F i g u r e 23. S i d e V i e w of A r e a s H e a t e d a n d C o o l e d
a t E n g i n e h T u mb e r 2 Cutoff
T h e m o s t p r o b ab l e s u s p e c t s f o r c a u s i n g this
t y p e of a n o m a l y i s a l e a k i n t h e a u g n le n t ed s p a r k
i g n i t e r (ASI) f u e l o r o x i d i z e r l i n e w i th t h e f u e l
l i n e t h e p r i r n e c a n d id a t e. ( F i g u r e s 24, 25, 26,
and 27 .
F i g u r e 2 4 . 5 - 2 E n g i n e I g n it i o n S y s t e m
It h a s b e e n p o s t u l a t ed t h a t a s lmal l leal< oc -
c u r r e d i n t h e l i n e 2 n d co n t ln u c d t o n i a n i f e s t i t s e l f
u n t il t h e r e c r a s a c o i n p l e t e r u p t u r e . At t h i s p o i n t
h o t g a s e s f r o m t h e c o i nb u s ti o i l c h a m b e r w o u ld
b a ck f lo \ v t h r o u g h o n e l e g o f t h e r u p t u r e d l i n e i n
the v ic in i ty o f the AS1 p o r t a n d r e s u l t i n h o t g a s
s p e wi n g o u t o n e p a r t of t h e b r e a k a n d r a v c r y o g e n i c
p r o p e l l a ~ t o m i n g ou t o f t h e o t h e r s e \ - e r e d en d .
T h i s p h e n o m e n a h a s n o t b e e n c o n l p l e t e ly d d p l i c a t e dunclcr c on t r o l l ed co l id i t io~l s t t il e t i me t h i s p a p e r
w a s w r i t te n .
F i g u r e 25 . L o w e r e n d o f ASI F u e l L i n e
F i g u r e 26 . Uppe r end of AS1 Fuel Lin e
F i g u r e 27. AS1 LOX Li ne
8/4/2019 Development of LOX-Hydrogen Engines for the Saturn Apollo Launch Vehicles
b u rn , h y d rau l i c s y s t em f a i lu r e , an d f a i lu r e o f th e engtne. A s a re su lt of an intensive s implif ica ' t ion
en g in e to r e s t a r t o n s eco n d b u rn . p ro g ram , th e J - 2 en g in e i s p ro g rammed fo r a
demo ns tra t ion of des ign ' in an upra ted vers ion in
Th e f i r s t b u rn o f th e 5 - 2 e n gi n e w a s n o r m a l u p t h e 1970 time f r a m e .
,--- to 695 s eco n d s a f t e r li ftof f. A t th a t t im e th e r ewas a n eng ine p e r fo rma n ce s h i f t an d a d i s tu rb an ce --
/ in environmenta l condi t ions .
T h e c h a m b e r p r e s s u r e d r op p ed , f u e l p u m p
d i s c h a r g e p r e s s u r e i n c r e a s e d , b o th t h e f u e l and
LOX n j e c t o r p r e s s u r e d e c r e a s e d , t h e f u e l in-
j ec to r . t emp era tu r e ro s e , amd t h e fu e l p u mp s p eed
wen t to ze ro rp m. F ig u re 3 1 in d ica te s th a t b o thh ea t in g an d co ol ing o ccu r r ed ex te rn a l to th e en g in e
dur ing a 15 second t im e in terval .
A s h a r p d r op i n t he c y l i n d e r o i l t e m p e r a t u r e
of the yaw actuator was r ecor ded a t 695 second s
to co r r e s p o n d wi th th e p r ev io u s ly men t io n ed en -
v ironmenta l changes .
t
Figure 31 . Su mm ary of Environlllell tal Condition
Changes
All precol ld i tioni l lg r equ irem ents w ere s a t i s -f ac to ry fo r th e s eco n d b u rn an d a l l v a lv es
cy c led p ro p e r ly . T h e s t a r t tr a n s i e n t w a s n o r -
m al un t i l the beginning of main s tage except for
c h a m b e r p r e s s u r e w h i ch f a i le d t o r i s e t o t h e
d es i r ed l ev e l in d ica tin g n o ig n it io n in th e ma in
ch amb er . T h e m o s t p r o b a b l e c a u s e f o r t h e f i r s t
burn anorr la l ies and t t e Cai lure to res tac t i n the
P xc nt n : n r ~ l
.&I'D 01 EEI or A S S I ~ 10 c h r ! Ir rn 1 ~ 7 1 a u l i orC?LhlCb l S1LXi;IED tVGI1:t I W 1970.
\
Fi gur e 32. J - 2 Engine Contr ibu tion .to Saturn V
Pay lo ad In c r eas e
S u m m a r y
c r a m h a s e n -he J - 2 engine development pro ,
countere d problems typ ical of a new prop uls i o~l
unit . To d a te n o p ro b lem h as ap p ro ach ed th e t ech -
n ica l complexi ty of the combus t ion ins tab i l i ty phen-
omen a found in the LO X-RP-1 engines . T h e p r e s -
ence of two cryoge nics mak es the dynamic balance
of the propuls ion s ys te m under a wide opera t ing
band a ve ry d i f f icu lt p roblem espe cia l ly dur ing the
s t a r t t r an s i en t p h as e . Th e b as i c en gin e d es ig n h as
beell thoroug hly evaluat ed and tested.
Fu tur e Outloolr .
Th e develop ment of l iquid oxygen-liquid hydrogen
engines is b u t an o the r t i ck m ark in th e ln i l e s to n es
of propuls ion , The pas t t rend ha s been to la rg er
engines bu t now a p la teau se em s to be forming .
F or the nea r fu ture , developments wi l l p robably
ev o lve a lo n g mo r e v e r s a t i l i t y in th e s y s t em, h ig h e r
imp ulse , and m or e re l iab i l i ty . One of the mo s t
p ro mis in g f i e ld s i s t h e lo w co s t b o o s te r u t i l i z ing
e i th e r p ack ag ed s to r ab le s o r s o l id p rop e l l an t s .
second burn i s a n AS1 fuel l ine f a i lu re . MathAcknowledgements
m o d el s p r od uc e s i m i l a r ~ e r f o r l n a n c e hi f t s fo r
fa i led AS1 fu e l l in es ; h o wev er , a l l ma l fu n c tio n s Th e a s s i s t an ce of th e man y p eo ple who co n t r i -
have not 1-e t been sa t i s fac tor i ly expla ined . T e s t buted to the prepara t ion of th is paper i s appr eci-p r o g r a m s a r e u n d er w a y t o d e m o n s t r a t e f l i gh t a ted . Th e au thor would par t icu la r ly- l ike to thankfa i lu r e mo d es .
p e r s o n n e l in th e Pro p u l s io n an d Veh ic le En g in ee r -
in g Lab o ra to ry an d o th e r l ab o ra to r i e s a t t h e
Uprating Mars h a l l Sp ace F l ig h t C en te r an d th e man y Sa tu rnCons is ten t wit11 the pa t ter n of the o ther la rg e c o n t r a c t o r s wl-?p contr ibu ted data and analyses for
liquid engines developed by NASA, the J-2 engine th e p r e l im in a ry co n c lu s io n s d r awn in th e f lig ht
- h a s b e en s t e a di l y i ~ n p r o v e d i n c e i t s c o n r ep t i on p r a b l e r n a r e a .
and contributed marlied1)- to vehicle payload in-
c r e a s e s a s s ho wn i n F i g u r e 32. Pay lo ad cap ab i l -
i ty in th e Sa tq rn V v e hi c le h a s b e en i n c r e a s e d a l -
m o s t 7000 lbs . ih rough improvexnents in the 3-2