Igniter capsule for chemical ignition of liquid rocket propellant

Gregory, J. W.

Straight, D. M.

English

NASA Technical Reports Server

June 2, 1964 D. M. STRAIGHT ETAL 3,135,090 
ROCKET MOTOR SYSTEM 
Filed March 30, 1962 2 Sheets-Sheet 1 
NG. / 
/I4 
INVENTORS 
DAVID M. STRAIGHT 
JOHN W. GREGORY 
https://ntrs.nasa.gov/search.jsp?R=19700029189 2020-03-17T02:15:06+00:00Z
June 2, 1964 D. M. STRAIGHT ETAL 3,135,090 
ROCKET MOTOR SYSTEM 
Fi led March 30, 1962 2 Sheets-Sneet 2 
'34b NG. 4 
INVENTORS 
DAVID M. STRAIGHT 
JOHN W. 
-Qd 
2- 
ATTORNEYS 
3,135,0943 Unted States Patent Ofice June 2, 1464 
L 
1 2 
FIG. 4 is an enlarged sectional view of still another 
3,135,090 embodiment of an ignition capsule constructed in accord- 
ROCKET MOTOR SYSTEM ance with the invention. 
David M. Straight, North Olmsted, mard John W. Gregory, In order to achieve the aforementioned objects there is p m a  Heights, Ohio, assifloss to the united States of 5 provided a rocket motor system of the type having an 
as liPy the of '" elongated interposed between a National Aero~amaaatics and Space Administration 
Piled Mm. 30,1962, Ser. Na. 183,977 nozzle and an injector, together with a source of liquid 
5 Claims. (@I. 60-35.6) proyellant that flows through the injector into the com- 
(Granted under Title 35, U.S. Code (1952), sec. 266) bust1011 chamber. A compact ignition system is mounted 
10 adjacent the combustion chamber and the system in- 
The invention described herein may be manufactured cludes a container of ignitor chemical that is introduced 
and used by or for the Government of the United States into the combustion chamber independent of the BOW of 
of America for governmental purposes without the pay- the propellant. 
rnent of any royalties thereon or therefor. Referring to the drawings, there is shovm in FIG. 1 
This invention is concerned with an improved rocket 15 a rocket motor system PO which includes a hollow, elon- 
motor system which utilizes a liquid fuel and, more par- gated combustion chamber 12 interposed between an in- 
titularly with a rocket motor having means for chemical jector 14 and a nozzle 16. A source of liquid propellant 
ignition that is independent of the fuel flow. The inven- such as a lank 18 is operably connected to the combustion 
tion is especially directed to  a compact igniter for engines chamber 12 through a supply line 20 that is in com- 
which burn nonhypergolic liquid propellant combinations. 20 munication with the injector 14. A second source of 
Various devices have been proposed for the ignition of liquid propellant such as a tank 22 is likewise in com- 
non-hypergolic liquid propellant rockets including electric munication with the combustion chamber 12 through a 
sparks, solid pyrotechnic charges and devices whqich inject line 24 that is customarily connected t o  the nozzle 16 for 
liquid ignitor chemicals in advance of the liquid propel- regenerative cooling. The specific types of propellants 
lant. The electrical spark ignition systems are limited 25 in the tanks 18 and 22 form no part of the invention, and 
in the amount of ignition energy that can be provided any type of non-hypergolic propellant that requires inde- 
without the use of augmentation chambers which tend to pendent ignition may be used. The flow of propellant 
complicate the propellant scheduling control. Also, elec- from the tank 18 is controlled by a valve 26 in the line 
tric power generation or storage equipment must be car- 20 while the propeilant flow from the tank 22 is likewise 
ried with the engine to  activate the spark system. The 30 coatrolled by a valve 28 in the line 24. If desired, the 
solid pyrotechnic ignitors are customarily inserted into valves 26 and 28 may be solenoid operated and activated 
the rocket chamber through the nozzle, and this requires by a suitable timer 30. 
the ejection of mechanical parts from the engine after According to the invention, an ignitor capsule 32 is 
ignition which may cause damage to the engine walls. mounted adjacent the combustion chamber I2 on the in- 
Previous devices far injecting a liquid ignitor chemical 35 jector 14, as shown in FIG. 1, for introducing liquid 
into the combustion chamber simultaneously with the ignitor chemicals into the combustion chamber inde- 
propellants have been complex in that they utilize separate pendently of the feeding of the liquid propellants from 
tankage and feed lines, pressurization and pnrge systems, the tanks 18 and 22. The ignitor capsule 32 comprises a 
check valves, loading valves, and shutoff valves which are compact assembly of elements which may be readily 
subject to malfunctioning. 40 transported and easily stored until used. The capsule 32 
It  is, therefore, an object of the dnvention to provide is easily mounted on the injector 14, and while its opera- 
an improved rocket system having means for chemically tion is independent of the flow of propellants from the 
igniting non-hypergolic fluid propellant combinations tanks 18 and 22, it may be actuated by the timer 30. 
which xilay be operated independently of the feeding of Referring to FIG. 2 the ignitor capsule assembly 32 is 
the propellant with a relatively small initiating impulse. 45 naounted on a surface 34 of the injector 14 opposite the 
Another object of the invention is to provide a com- injector face 36 in the combustion chamber 12. For con- 
pact liquid chemical ignition capsule that is entirely self- venience, the portion of the injector 14 shown in FIG. 2 
contained, easily manufactured, and highly reliable in is illustrated as being solid; however, the construction of 
operation. the injector I4 forms no part of the present invention and 
Still another object of the invention is to provide a 50 may be of a number ?f types. For example, the injector 
chemical ignition system for a fluid propellant rocket 14 may contain a pair of separated chambers, one for 
which is cstgable of delivering a relatively high quantity receiving propellant from the line 20, and the other for re- 
of ignition energy continuously during starting and has ceiving propellant from the line 24. The propellants are 
a positive shutoff of the injection port after ignition. then injected into the chamber 12 through a plurality of 
A further object of the invention is to  provide a liquid 6.5 orifices. 
ignitor chemical capsule that has great flexibility because The capsule assembly 32 comprises a generally cylin- 
of its adaptability to a variety of engine operating condi- drical housing 38 secured to a base plate 40 having a cen- 
tions and environments. trally disposed protuberance 42 that is received in a mating 
Other objects and many attendant advantages of the depression in the injector 14 so that the base plate 40 en- 
present invention will be apparent from the specification 60 gages the surface 34. A nozzle 44 is mounted on the 
which follows and from the drawings in which like nu- prptuberance 42 and extends through an aperture in the 
merals are used throughout to identify like parts. injector 14  to the interior of the combustion chamber 12. 
In the drawings: A passage 46 in the nozzle 44 is aligned with a mating 
FIG. 1 is a view in elevation of a rocket motor system passage 47 in the protuberance 42, and the passage 46 
constructed in accordance with the invention; 65 terminates at the injector face 36 to form an orifice. 
FIG. 2 is an enlarged sectional view taken along the A spring bellows 48 is mounted in the housing 38 with 
line 2 - 2  in FIG. 1 showing one embodiment of a capsule one end secured to the base plate 40 and the opposite end 
assembly utilized in a chemical ignition system con- secured to a cup 50 which forms a movable wall. A 
structed in accordance with the invention; liquid ignitor chemical such as chlorine trifluoride is pre- 
FIG. 3 is an enlarged sectional view illustrating an 70 loaded in a chamber 52 formed by the base plate 40, the 
alternate embodiment of an ignition capsule constructed spring bellows 48, and the cup 50. Discharge of the 
in accordance with the invention; and ignitor chemical from the chamber 52 through the pas- 
3,135,090 
3 4 
sages 46 and 47 is prevented by a rupturable diaphragm between a nozzle 44b and a protuberance 42b on the base 
in the form of a frangible disc 54 mounted between the plate 40b which seals a passage 47b from a passage 46b. 
nozzle 44 and the protuberance 42. The frangible disc 54b is punctured by a pointed plunger 
When the liquid ignitor is to be ejected from the cham- 104 mounted on the cup 100 which is moved toward the 
ber 52 into the combustion chamber 12, the disc 54 is 5 base plate 40b by permitting a highly pressurized gas in 
ruptured by a pointed plunger 56 that extends through the a storage bottle 106 to expand into a chamber 108 on the 
end of the housing 38 opposite the base plate 40. The opposite side of the cup 100 from the chamber 102. The 
plunger 56 is mounted on the movable cup 50, and as this chamber 108 is bounded by a portion of the housing 96, 
cup moves toward the base plate 40 under the influence the storage bottle 106, the cup 100, the bellows 98, and a 
of a coil spring 58, the pointed end of the plunger 56 10 peripheral portion of the base plate 40b. The storage 
breaks the disc 54. Further movement of the cup 50 bottle 1184 is vented to the chamber I08 by actuating an 
ejects the ignitor chemical from the chamber 52 and explosive type valve 110 that is mounted on the end of 
causes the pointed end of the plunger 56 to move along the housing 96 opposite the base plate 40b. The valve 
the passages 46 and 47. The plunger 56 is spaced from 110 contains an explosive squib I12 that, when ignited 
the walls of the passages 46 and 47 by radially extending 15 by the electrical leads 64b and 65b, shifts a spool 114 to 
ribs, and the plunger is retained in its retracted position place a passage 116 from the storage bottle PO6 in com- 
with the spring 58 compressed, as shown in FIG. 2, by a munication with a passage PI8 that leads to the chamber 
latch pin 68 that engages a slot in the plunger 56. A I@$. 
charge within a cartridge 62 on the end of the housing After the valve 110 has been actuated and the ignitor 
38 is exploded by an electric current carried by leads 64 20 fluid has been expelled from the chamber 102 by move- 
and 45 from any suitable source such as the timer 30 in ment of the cup XOO. the passage 57b is sealed by seating 
FIG. 1 to withdraw the latch pin 60. A solenoid may a tapered portion 11269 of the plunger I04 adjacent the 
also be used to move the latch pin 60 out of engagement cup 1063 in a mating entrance to the passage 47b. The cup 
with the plunger 56. 100 and the plunger 104 are maintained in the extended 
An important feature of the invention is that when sub- 25 position with the tapered portion 120 in engagement with 
stantially all of the ignitor fluid has been expelled from the entrance of the passage 47b by a non-return lock 
the chamber 52 by the cup 50, the passage 47 is sealed by washer 122 that is mounted on a ring I24 on the cup 100 
a tapered portion 66 which seats in a mating entrance por- adjacent the bellows 98. 
tion of the passage 47. The plunger 56 is maintained in While the preferred embodiments of the invention have 
its extended position by the spring 58 and movement to- 30 been disclosed and described, various modifications may 
ward the retracted position is prevented by a tapered pin be made t o  the capsule structure without departing from 
68 that is moved to a locking position by a spring 76) as the spirit of the invention or the scope of the subjoined 
the plunger 56 moves toward the base plate 40. claims. For example, a pluraJity d capsules may be man- 
Referring now to FIG. 3 there is shown an ignitor car- ifolded for a multiple restart ignition system. Likewise, 
tridge 32a which comprises a generally cylindrical wall 35 the capsules may be indiviriually located at  various injec- 
72  having one end secured to a base plate 40a and the op- tion ports at the injector face. 
posite end secured to a head plate 74.  A spring bellows What is claimed is: 
76 has one end secured to the head plate 74 and the op- 1. A capsule assembly for injecting an ignitor chem- 
posite end secured to a generally circular disc 7 8  form- ical into a rocket engine through an injector, said capsule 
ing a movable wall within the confines of the cylindrical 40 assembly comprising 
wall 72.  A liquid chemical ignitor is preloaded into a a plate h ~ v i n g  a surface for engaging said injector, a 
chamber 80 formed by the base plate 40a, the cylindrical protuberance extending from said plate, said pro- 
wall 72, the disc 78,  the bellows 76, and a peripheral por- tuberance having a first passage extending there- 
tion of the head plate 74.  Discharge of this fluid through through, 
a passage 47a in a protuberance 42a on the base plate 4Qa 45 a nozzle mounted on said protuberance for extending 
and an aligned passage 46a in a nozzle 44a at an injector through said injector, said nozzle having a second 
face 36a is prevented by a frangible disc 54a mounted be- passage extending therethrough in substantial align- 
tween the nozzle 44a and the protuberance 42a. The ment with said first passage, 
frangible disc 54a is punctured by a pointed plunger 82 a housing secured to said plate on the opposite side 
carried by the disc 78  during sliding movement into the 50 thereof from said protuberance for containing said 
passage 46a and 47a. ignitor chemical, 
The disc 7 8  and the plunger 82 are moved by igniting a a frangible disc mounted between said nozzle and said 
gas-generating squib 84 by electric leads 64a and 65a. The protuberance for closing said first and second pas- 
squib 84 is contained in a cartridge 86 on the head plate 7 4  sages, 
that is in communication with an expandable chamber 55 a movable wall within said housing on the opposite 
88 defined by the head plate 74,  the bellows 76  and the side of said ignitor chemical from said plate, 
disc 78.  When the squib 84 is ignited the chamber 88 is a plunger for rnpturing said disc, 
filled with a gas which moves the disc 78  toward the means for moving said wall and said plunger sirnulta- 
base plate 4@a thereby causing the plunger 82 to pierce neously toward said plate whereby said plunger rup- 
the disc 54a, and when all of the ignitor fluid has been ex- c0 tures said disc and said ignitor chemical is ejected pelled from the chamber 80, the passage 47a is sealed by through said first and second passages, said plunger 
engagement of a tapered portion 90 of the plunger 82 
with a mating portion at  the entrance of the passage 47a. having a tapered portion for seating engagement 
The plunger 82 is locked in its extended position by spring with the entrance to said first passage for sealing the 
loaded pins 92 in the disc 7 8  that engage a circumferential 65 same when substantially all of said ignitor chemical 
slot 94 in the cylindrical wall 72. has been ejected, and 
Referring now to PIG. 4 there is shown another embodi- means for maintaining said tapered portion in seating 
ment of an ignition capsule 32b which comprises a hous- engagement with said entrance to said first passage. 
ing 96 having its normal open end secured to a base plate 2. A capsnle assembly for injecting an ignitor chemical 
48b. A spring bellows 98 within the housing 96 has one 70 into a rocket engine through an injector, said capsule as- 
end secured to the base plate 4Qb and its opposite end sembly comprising 
secured to a cup 160, and the chemical ignitor liquid is a plate having a protuberance extending from a first 
preloaded in a chamber I02 formed by the base plates surface thereof toward said injector, said protuber- 
40b, the bellows 98, and the cup 100. This fluid is re- ance having a first passage extending therethrough, 
tained in the chamber 102 by a frangible disc 54b mounted 75 a nozzle mounted on said protuberance, said nozzle 
3,135,080 
5 6 
having a second passage extending therethrough in tain said tapered portion in seating engagement with 
substantial alignment with said first passage, said entrance to said first passage. 
a housing secured to a second surface on said base plate 3. A capsule assembly, as in claim 2, wherein said 
for containing said ignitor chemical, locking means comprises 
a frangible disc mounted between said nozzle and said 5 a pin for engaging the end of said plunger remote from 
protuberance for closing said first and second pas- said end portion. 
sages, 4. A capsule assembly, as in claim 2, wherein said 
a spring bellows positioned within said housing, housing has a slot adjacent said plate, and said locking 
a movable wall mounted on said spring bellows within means includes at least one radially extending pin carried 
said housing on the opposite side of said ignitor 10 by said wall for engaging said slot. 
chemical from said plate, 5. A capsule assembly, as in claim 2, wherein said 
a plunger mounted on said wall and having an end locking means comprises 
portion extending into said first passage, a lock washer carried by said wall for engaging the 
means for moving said wall and said plunger toward interior surface of said housing. 
said plate whereby said end portion of said plunger 15 
ruptures said disc and said ignitor chemical is ejected References Cited in the file of this patent 
through said first and second passages, said plunger UNITED STATES PATENTS 
having a tapered portion remote from said end por- 810,403 Fulton et al. ----------- Jan. 23, 1906 
tion and adjacent said wall for seating engagement 2,505,798 skinner ---- M~~ 2, 1950 
with the entrance to said first Passage and sealing 20 2,847,148 Altseimer -------------- Aug. 12, 1958 
the same when subslantially all of said ignitor chem- 2,858,942 Lucien -- ----- NOV. 4, 1958 
ical has been ejected, and 2,924,359 Beremand ------------- Feb. 9, 1960 
locking means for retaining said wall adjacent said plate 2,959,007 Gregory et al. --------- Nov. 8, 1960 
after said ignitor chemical has been ejected to main- 2,974,484 Cooley ---------------- Mar. 14, 1961 


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