Solid propellant ignition with hypergolic fluid injected to predetermined portions of propellan

Allen, H., Jr.

Ciepluch, C. C.

Fletcher, E. A.

English

NASA Technical Reports Server

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March 16, 1965 H. ALLEN, JR., ETAL 
A P P A R A ~ S  FOR IGNITING SOLID PROPELLANTS 
Filed March 16, 1962 2 Sheets-Sheet 1 
l NVENTORS 
HARRISON ALLEN JR. 
CARL C. CIEPLUCH 
EDWARD A.FLETCHER 
4iao@2 
ATTORNEY 
https://ntrs.nasa.gov/search.jsp?R=19700024064 2020-03-17T01:33:09+00:00Z
March 16, 9965 H. ALLEN, JR., ETAL 3,173,25 1 
APPARATUS FOR IGNITING SOLID PROPELLANTS 
File$ March 16, 1962 2 Sheets-Sheet 2 
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INVEXTOR 
HARRISON ALLEN J R .  
C A R L  C. C I E P L U C H  
EDWAR D A FLETCHER 
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3,173,251 1 United States Patent Office Mar. 16, 1965 
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3,173,251 of the tube, and nleans for concentrating the fluid at the 
FOR EGNITIWG SOLIE ttlbe end to react with the propellant before escaping 
PROPELLANTS from the opposite end of ths rocket nozzle. 
Mamison Allen, Jr., Cleveland, and Carl C. Cieplrrcb, Referring to the dmwings, there is shown in FIG. 1 a 
Berea, Ohio, and Edrrad Abraham Pletchen; Minne- 5 testing apparatus for determining the eeffcts of ditferent 
apolis, Miiin., assignors to the United States of Anperlea ignition nixids and various injector configurations, to- 
2s represented by the AdminisWitor of & Natiofial gether with other features relating to the ignition cf a 
Aeronautics and Space Adrninistrafion 
Filed Mar. 16,1962, Ser. No. 180,370 rocket engine. This testing apparatus con~prises a solid 
4 Claims. (CI. 40-35.61) propellant motor 21 having a head 12 such as a block 
( ~ ~ ~ ~ ~ ~ d  Plncjer gse 35, U.S. .pode (g9';2), set. 206) 10 of steel or other similar rnaterial located at its upstream 
end. A tap 13 for conveying an ignition fluid and a 
The invention described herein may be manufactured chaillber pressure passage 14 are dl-illed in the block ~ 2 .  
and used by or for the Government of the United Sates The testiilg apparalus utilizes an igllition system ~ h i c h  
of America for governnlental purposes wiihoi~t the Pali- includes a storage bottle 15 connected to a colltrol valve 
ment of any royalties thereon or therefor. 15 H6 that may be operated remotely by a powered inechani- 
This invention pertains to the ignition of solid propel- cal device (not sllown). Tkle bottle 25 is previously filled 
lant rocket lllotors and, more partic~lariy, to the ignition wiih a measnred qualltity of ignition fluid and pressurized 
of solid propellant rocket motors by the injection of hy- with a non-reactive gas such as helium. Additionally, 
pergolic fluids. Ihc ignition s!rs!em has a chec!~ valve 17 between the 
Solid propellant rockets are customarily ignited by fir- 20 control valve lg sild the tap 13. 
ing a small quantity of a pyrotechnic powder, such as A double-walled cylindrical chamber IS encloses a 
black powder, in the form of a squib. Igniters of this h~!low charge consisiing of a mass of solid propellant 
type have many disadvantages, snch as great tenperatcre ia the form of an elongated tube 19. The solid propel- 
sensitivity which requires certain environmental condi- lant in the tub-, 19 is preferably a colllposite consisting 
tions, unpredictable sheif life which res~l!ts in detericra- 25 prinlariiy of poiysu:fide po]ymer fuel and amnloniunl 
tion, complicated mechanical Paris which may not be perchlorate oxidizer. Th:: challlber liS is rigidly attached 
able, and rigid quality control requirements. to a. protuberance in the form of a threaded boss 20 
In order to solve these problems, ii has been propo~" extending froill a surface of the head 12, An opening 
to distribute a chemical fluid such as broiaine trinuoride coillpr~sillg a bore having a plurality of longitudinal 
or chlorine tiifluoride over a large area of a Illass of 30 grooves 21 forilled in the wall thereof extends along 
solid propellant. The fluid reacts hypergolicaIly with entire axial lenglh of the tube $9 from a nozzle 22 to the 
either the fuel or oxygen component of the propel1aii.t boss 29. The nozzle 22 is of tile coilventional convergent- 
grains to Cause ignition. However, this ignition is Cot divergent type 2nd is rigidly afi::ed to !he dowllstreanl 
sin~ultaneous and an objectionable delay SP,SU!~S which end of the cyliildrical casing 18 for conducting gases ex- 
makes firing at a precise tiine difficult lo obtain. 35 hausted from the rocket engine 10. 
It is, therefore, an object of the invention to provide According to the investion, 11ypergolic ignition fluid, 
a11 improved apparati:~ for igniting a Illass or' solid pro- silch as chlorine trifluoride, bromine (rifluoride, or bra- 
pellants using a hypergolic igniting fluid. mine perltailuoride stored ia the bottle 85 in a nleasured 
Another object of the invention is to provide an appn- quantity such as five cubic centimeters, passes through 
ratus for igniting a mass of solid pI'opei!ant iliiii~isg the valves 16 acd 17 inlo the tap 13. This measured 
hypergolic fluids wherein the igniting substance is con- quantity of fluid is then introduced into the head of 
centrated on predetermined pcrtions of the propellant. the opening in the propellant charge 19 by a suitable 
A still further object of the invention is to provide an injector apparatus 23 associated with the boss 20 where 
apparatus for studying the ignition of a solid propellani 45 the f-',uid is directed against preselected por[ions of the 
rocket using a hypergolic fluid. inside walls of the opening. 
Cther objects of the invention will be apparent from A pressure transducer 24 is positioned adjacent the 
the following description when taken together v~irh th- head B2 by an intermediate block 25 through wxch the 
accompanying drawings wherein like nn~neraIs are used passage 14 in the head 12 also passes. 'Tile trallsducer 
throughout to identify like parts. 50 24 is connected to the ?assage 44 for measuring the 
In the drawings: chamber pressure, and this device can be of the strain 
FIG. 1 is a partially sectioned, ozrspective view of a gage type. The pressure side of thc transducer 24 an& 
coil~posite propellant iuotor having in:prove:l ignitioil vertical pressure Iine above it are filled with a high tem- 
apparatus for perfornling the method of the invention; perature silicone oil for protection from combustion 
FIG. 2 is an enlarged sectional view of the preferreci 55 gases. An electrical signal from the pressure transducer 
embodiment of a hypergolic flu2 injector ~onstructed in 24 is recorded oil a direct recording osciliograph 26 
,accordance with the inveillion; which d s o  measures ignition delay. This is accom- 
FIG. 3 is an enlarged seciional view of an a!ternaie p!ished by imposing a separate signal on the oscillograpli 
embodiment of the injector; record at the moment when the valve 16 is opened there- 
FIG. 4 is an enlarged se.ciioiia1 view of another em- 60 by nlarking tiine zero. The ignition delay is the elapsed 
bodinlent of the injector; and time from the marked tiin:: zero until the chtmber pres- 
FIG. 5 is an enlarged sectional view of still another sure rises to SO percent of its normal value. This igni- 
embodiment of the injector. t i ~ n  delay colnprises both dead t ixe and reaction time; 
In order to achieve the above listed objects there is the dead time bring the tiine required for the fluid to 
provided a rl~etliod of igniting a ti~bular luass of salid 65 reach the injector after the opening of tile valve 16 while 
propellant in which a measured quanlitjl of hypergnlic the reaction time is delerrnined by subtracting the dead 
fluid is injected into an opening in the iubillar mass, and time from the ignition delay. The dead time which is 
this Auid is directed against predeleriliined portions of determined by high-speed photography is a constant of 
the walls of thc opening. There is also provided appa- about 1.1 secon~is for thc disclosed testing apparatus. 
ratus for performing the method of the invention which 70 The preferred form of the invention is illustrated by 
includes an injector mounted at one end cf a prop~ll.??it the pocket type injector 23 in FIGS. 1 and 2. This injec- 
charge for supplying the hypergolic fluid inlo the interior tor cor!;prises an elongated iliembcr such as a tube 30 
8,173,251 
3 4 Pg 
that extends into the bore formed in the mass of solid tion or the scope of the subjoined claims. For example, 
propeliant 19. A longitudinally extending passage in the the invention is not limited to any particular type of solid 
tube 30 is in colnmunication with the tap 13 for con- propellant, and the various types of injectors that have 
veying hypergolic fluid into an enlarged pocket 31 formed been disclosed as being used with composite solid pro- 
in the end of the charge of solid propellant 19. A mass 5 pellants are equally applicable to double-base propellant 
of solid propellant such as a disk 32 of plasticized poly- motors. Also, the hypergolic fluids are not limited to 
vinyl chloride and ammonium perchlorate is positioned the three particular aforementioned fluorides. 
adjacent the tube 30 at the bottom of the pocket 31. The What is claimed is: 
fluid is concentrated in the pocket 31 to react with both 1. Apparatus for igniting a tube of solid propellant 
the solid propellant of the tube 19 and the disk 32 before 10 having a longitudinal bore extending therethrough, said 
it escapes through the nozzle 22 after the disk 32 burns. apparatus comprising 
The pocket type injector 23 was mounted in the ap- means at one end of said tube for directing a stream of 
paratus shown in FIG. 1, and two tests were performed hypergolic fluid along the axis of said bore, and 
using 5 cubic centimeters of chloritie trifluoride pres- a member positioned in the path of said stream of 
surized with 15 p.s.i.g. helium gas. The tube 30 had an 18 hypergolic fluid for deflecting the flow thereof toward 
inside diameter of 0.104 inch and extended into a one the wall of said bore and initially concentrating said 
inch diameter pocket 31 for a distance of %-inch. The fluid at said one end to react with said solid pro- 
disk 32 was positioned 1% inches from the head end of pellant in said tube before escaping from the opposite 
the charge 19, and the two tests produced reaction times end of said bore. 
of 0.3 1 and 0.34 second. 20 2. Apparatus for igniting a tube of solid propellant 
Referring to the embodiment of the invention shown in having a longitudinal bore extending therethrough, said 
FIG. 3, the injector means 23a comprises a longitudinal- apparatus comprising 
ly extending tube 35 having its innermost end 36 closed. injector means mounted at one end of said tube for 
A plurality of radial apertures 37 extend through the introducing hypergolic fluid into said bore, said in- , 
walls of the tube 35 to concentrate the hypergolic fluid 25 jector means conlprising 
on the walls of the solid propellant charge 19. an elongated member extending into said bore at 
A radial injector of the type shown in FIG. 3 com- said one end thereof, said member having a 
prising a tube 35 having an inside diameter of 0.104 inch longitudinally extending passage therein for 
was tested in the apparatus shown in FIG. 1. This tube conveying said fluid therethrough into said bore, 
35 extended into the bore for a distance of %-inch and 30 and 
four radially-drilled holes 37, each having a diameter of a mass of solid propellant positioned in said bore adja- 
0.06 inch were provided for directing the fluid against cent said elongated member for forming an obstruc- 
the solid propellant. Hypergolic fluid in the storage bot- tion which initially blocks the flow of said hyper- 
tle 15 was pressurized to 15 p.s.i.g. and reaction times golic fluid thereby concentrating said fluid at said 
of 0.55 and 0.59 second were observed. 35 one end to react with said solid propellant in said 
Referring now to the Y type injector means 23b shown tube and said mass before escaping from the op- 
in FIG. 4, hypergolic fluid is conveyed to the head end of posite end of said bore. 
the tube 19 of solid propellant through the tap 13 as 3. Apparatus for igniting a tube of solid propellant as 
previously described. Passages 40 and 41 are drilled in claimed in claim 5 wherein the mass of solid propellant 
the boss 20 to the tap 13 forming jets to concentrate the 40 in the bore comprises a disc of plasticized polyvinyl chlo- 
hypergolic fluid at the head end of the tube 19. ride and ammonium perchlorate. 
A Y type injector shown in FIG. 4 was tested in the 4. Apparatus for igniting a tube of solid propellant as 
apparatus shown in FIG. 1. This injector included a pair in claim 1, wherein said member deflects the flow of the 
of drilled passages each having a diameter of 0.072 inch stream of hypergolic fluid at an angle relative to the longi- 
that were located at an angle of 90 degrees from one an- 45 tudinal bore of said tube. 
other. A spacing of 0.313 inch was provided between 
the ends of the passages 40 and 41, and a reaction time of References Cited by the Examiner 
0.71 second was observed when the hypergolic fluid in UNITED STATES PATENTS 
the bottle 15 was pressurized to 15 p.s.i.g. 50 2,685,168 8/54 Malick -------------- 60-39.74 
m he axial type injector 23c shown in FIG. 5 consists 2,698,514 1/55 Hull et 60-35.6 4 
of an elongated tube 44 coaxial with the bore in the tube 2,708,341 5/55 Zucrow ------- 60--39.06 , 
19 of solid propellant. Such a tube 44 having an inside 2,850,975 9/58 Teague --------------- 60-35.6 
diameter of 0.104 inch was mounted on the apparatus 2,859,588 1/58 Wilson --- 60-39.74 
shown in FIG. 1 to extend into the bore in the solid pro- 55 2,955,420 Schirmer 66"39.06 pellant charge 19, a distance of %-inch. A reaction time 2,972,227 2/61 Allen 600--39.45 
of 0.91 second was observed when the hypergolic fluid 2,974,484 3/61 Cooley 60-39.82 
was pressurized to 15 p.s.i.g. 2,984,973 5/61 Stegelman ------------ 60-35.6 
the data in the above was obtained, 2,990,682 7/61 Mullaney ---- -- 60-35.6 
using a measured quantity of 5 cubic centimeters of igni- tion fluid, a compos~te motor was aho ignited 60 3,068,641 12/62 Fox ----------------- 60-35.4 
3,128,599 4/64 Carr ----------------- 60-35.6 
with 2.5 and 10 cubic centimeters of chlorine trifluoride. 3,144,751 Blackman et - 66"35,6 
The ignition characteristics observed were approximately 
the same for all these fluid quantities. 
Several illustrative embodiments of the invention have SAMUEL LEVINE, Primary Examiner. 
been disclosed and various structural modifications may 65 CARLTON R. CROYLE, Examiner. 
be made withput departing from the spirit of the inven- 


Apparatus for igniting solid propellants Patent

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