Solid propellant rocket vehicle thrust control method and apparatu

Gin, W.

Piasecki, L. R.

Robillard, G.

English

NASA Technical Reports Server

Feb. 25, 1964 THOMAS KEITH GLENNAN 3,122,098 
ADMINISTRATOR OF THE NATIONAL 
AERONAUTICS AND SPACE 
ADMINISTRATION 
APPARATUS AND METHOD FOR CONTROL OF A SOLID 
FUELED ROCKET VEHICLE 
Filed Nov. 25, 1960 
https://ntrs.nasa.gov/search.jsp?R=19700028865 2020-03-17T02:13:51+00:00Z
I C 3,122,098 United States Patentr Office ,,, ,, ,,
1 2 
constricted to form a throat 8 fitting around the rim 7 
3,122,098 and terminating in a ffange 9 which mates with the flange 
j APPARATUS AND METHOD FOR CONI"I'OL OF A 6. The forward face of the flange 9 slopes rearwardly SO- FUELED ROCKET VEHICLE so that the distal face  of the flanges converge radially 
Th- Keith Gk-9 of N- 6 outwardly. The internal diameter of the throat 8 bears 
& ~ ~ I I ~ = ( o n A ~ ~ ~ ~ R M - - ~  a preselected ratio to the diameter of the nozzle throat 
CeolRcy Robillrrd S as will be brought out hereinafter. 
FiId Not. 25,1960, Scr. Na 180,374 Tbe flanges 6 and 9 are held together by a band as- 
4 Clrimr. (Cl. l O U 9 1  sembly 10. The band assembly includes inner band 10 member 11 of channel shaped cross section having radial- 
This invention relates to apparaNs and method for ly inwardly diverging side walls terminating in opposite- 
control of solid fueled rocket vehicles, more particularly IY directed reinforcing lips. The inner band member fits 
to terminal control of thrust of wch rocket vehicles in over the flanges 6 and 9 and clamps the flanges axially 
order to predetermine the trajectory thereof. as the band is constricted. The radially outer portion of 
Included in the object of this invention are: 11) the inner band joining the diverging walls is in the form 
First, to provide an apparatus and method for control of a cylindrical web. Secured to the web by spotwelds 
of solid h e l d  r w b t  vehicles whmin accurate and pre- Or other means is an outer band 12 which is cylindrical. 
determined reduction and termination of thrust may be The inner and outer bands are split at one or more 
dected from a m o t e  a t i o n  so as to effed vernier ad- points, depending upon the diameter of the juncture be- 
justmen* of nu!ge and velocity & tb - M. 00 tween the motor and nozzle structures. It is not essen- 
Second, to provide an apparatm and method for con- tial that thc outer band be coextensive with the inner 
crol of solid fueled rocket vehicles wherein reduction band: iqstead, short segments adjacent the split extremities 
and ternination of thrust is ef fww without producing of the inner band may be substituted. At each split ex- 
transient thrust peaks, or producing side thrus:~. tremity of the innet band, the outer band, or band seg- 
m r &  to provide an apparatus and method for con- @ ments is doubled upon itself to form a loop 13 which 
trol of solid fueled r w b t  vehiles which takes place is provided with a transverse slot 14. 
in two stages wherein first, the nozzle is ~eparatcd on The loops 13 are joined by a 7-bolt 15 having a cross 
command from the rocket motor chamber to reduce member 16 journalled in one of the loops 13, and a 
chamber pressure and heace thrust and second, the mo- shank 17 extending through the slots 14 of the two loops. 
tor chamber itself is separated on command from the QO The'other loop receives a tubular T-shaped elemtnt 18 
remaining components of the rocket vehicle and there- having a cross or jovmal portion 19 fitting the remain- 
upon caused to decelerate. ing loop 13 and a tubular sleeve portion 20 adapted to 
With tRe above and o b k r  objects in view as may a p  fit slidably on the shank 17. The shank protrudes , 
pear hereinafter, reference is directed to the accompany- through the sleeve Portion 20 and its protruding ex- 
ing drawings, in which: 1~ tremity is screwthreaded to receive a npt 21. When the 
FIGURE 1 is a reduced substantially diagrammati- nut is drawn tight, the inner band member 11 is tight- 
cal view showing the payload, motor, and nozzle struc- ened on the flanges 6 and 9 and securely holds the motor 
tures of a rocket vehicle, with the connecting bands re- and nozzle structures together. I 
moved and the structures shown separated. The forward end of the motor structure 2 is internally 
FIGURE 2 is an enlarged fragmentary longitudinal sec- 40 constricted to form a forward throat 22, the diameter 
tional view taken through 2-2 of FIG. I showing the of which bears a preselected ratio to the diaineters of 
motor and nozzle sections joined by a connecting band. the nozzle throat S of the nozzle structure and rearward 
FIGURE 3 is a similar enlarged fragmentary longitudi- throat 8 of the motor structure. Externally the motor 
nal sectional view taken through 3-3 of FIG. 1 showing structure is provided with a forwardly continuing skirt 
the motor and payload structures Joined by a connect- 4 j  23 surrounding the throat 22 and terminating in an ex- 
ing band. krnal flange 24 which confronts a corresponding ex- 
FIGURE 4 is a transverse sectional view taken through ternal flange 25 at the =mvard end of the payload struc- 
4-4 of FIG. 2 showing the connecting band in position. ture 1. The rearward end of the payload structure is 
FIGURE 5 is a similar transverse sectional view taken provided with a portion 26 including a central heat resist- 
through 6 5  of FIG. 3. 60 ant pad 27 covering and sealing the throat 22. 
FIGURE 6 is a fragmentary elevational view of the The confronting flanges 24 and 25, except for greater 
mo:or and payload structures and the connecting band, diameter. a n  identical to the mating flanges 6 and 9, and 
the vitw being taken from U of FIG. 5. have radially outwardly converging faces which m i v e  a 
FIGURE 7 is an enlarged, partially sectional, partialty second band assembly 28, the elements of which may be 
elevational view taken through 7-7 of FIG. 6 showing 65 identical, except for diameter, to the dements of the band 
the severing knife and its remotely actuated aperating assembly 10 and arc similarly identified. For purposw 
charge. of illustration, the band assembly 28 is shown as split 
A rocket vehicle adapted to this invention includa a diametrically. 
payload structure 1, a motor structure 2 mtaining a Fitted on each of the shanks 17 of the T-bdts 15 of 
. solid propellant 3, and a n d e  structure 4. the two bapd assemblies is a rembtely actuated severing 
b The nozzle structure is in the form of a truncated ' dev* 29. Each severing device includa a tubulu shell 
cone +ring forwardly to form a throat 5. At the 30 having a transverse hole whicb reaives the shank 17' 
throat end, the nozzle structure is provided with an ex- of a T-bolt. Within the shell 30 is a cylinder 31 having 
ternal flange 6 having sloping or beveled face at its rear- a shearing edge 32 adapted, when forced against the shank 
ward side and planar at its forward side. The flange is 17, to sever the lank.  At the opposite side of the win- 
preferably located rearwardly of the forward extremity der 31 from the shank 17, the sleeve is provided with a 
of the throat, which forms a forwardly projecting rim 7 .  propellant charge 33 capable of generating sufficient force 
The motor structure is in the form of a cylindrical to shear the l a n k  17. The end of the slteve remote &am 
tube into which has been cast a conventional solid the shank is provided with a cap 34 tbrough which. pass 
propellant 3 having a central bore of conventional cross ro Ignition wires 35. A suitable electrical igniter, not shorn, 
section. Conventional igoition means, not shown, are is incorporated in the propellaat charm 33. C 
provided. The rearward end of the motor structure b It is customary to provide in rocket vehicles a power 
I \ .  , "*I - 
' . +laa,o*&t - " . . .> L . I  * ,..,. {. 
, -, ' b :  ' 
3 ... . \ -- T '. . a  *. 
source to operate the various devices contained in. the To achieve the desired. condition in which instantane- 
payload structure, and to provide control means subject ously, there is no change in.thrust it is necessary ,that: 
to remote command. Such conventional means is repre- 
sented diagrammatically as a battery 36 and switches 37 ( 5 )  CF~A 6'CF2A 8 
and 38 for independent control of the severing. devices 6 Thus it is possible to sorve lPof CFZ and A8 between the 
associated respectively with the band assemblies 1@ and 28. 1s t  WO eqiiations, cShce all th& .&her parmeters W& 
The practice of the method for controlling a rocket known ~ Q T  a given o&Yathg 6onditioa: . 
vehicle utilizing the apparatus hereinbefore descm'bed, is- : ',.In general? CtZ, :not red%'at,the %due-wed-by1 
as follows: . . the bBove' qp&o,n,,@utdn,@~c ~ondii ion~Wl "d be -a- 
Initially the payload, motor and n d e  strncture are' 10 tablisded at the8new &oat"atea:"G . $ l ~ ' ~ @ ~ a t . ~ m e  
secured in series by the clamp dssemblies 18 and* 28. value greaW.,$an unity. qnd, incw?$f&b,~ut 1.25 .(&- 
After firing, and before burnout, and also before it is de- I pendime on the spe-heat ratio of,&gases) when local 
termined that thrust should be completely terminated, the sonic conditions are reached. The chamber pressure will 
severing device connectedwith the clamp band assembly adjust ta  a. lower level. determined by Aa and hence a 
10 is actuated by remote command. The clamp band as- 16 lowered sustaining levels of h s t  is now available for 
sembly immediately spreads radially, freeing the n o d e  vernier operation. At. a desi~ed Dime, the, thrust may be. 
structure 4 from the motor structure 2. As a consequence, cancelIed by fhe next step of separating the rnotor~stru~ 
the effective throat area,changes from' the area of the. ture from the payload structure. 
throat 5 to the area of the throat 8 of the motor structure . In determining the, separation plane at. the forward 
2, causing, when equilibrium is reestablished, a cbrre- 20 end,, the following cansideratians must be made.. Be- 
spondiig reduckion in thrust. i . .  cause, prior to- separation, there is na laow in tbe hemi- 
The rocket vehicle is permitted to continue at reduced spbricd lorward end of, the motor s t w e  2, ,the mo- 
thrust for vernier contra1 of its course; then at ths appro- : nlentary h a t  coewent due topartitioncat t h  f o r w ~ d  
priate time severing devices connected with the clamp end is unity. There, the instantaneous reverse thrust is: 
band 28 are actuated by remote command. The net ~6 (61 
thrust, due to the opposite open ends of the motor struc- : . , P C ~ Z  . 
ture, is for an instant, zero; however, on establishing of TO cancel the forward thrust, it is required'that: 
equilibrium by reason of flow from the forward throat 2% . (73 ~. 
there is produced a net forward thrust decelerating the . CFz~c&=~a&a ' 
motor structure. This has the effect of accelerating the 30 where 
-
motor structure away from the payload structate. An: the hrea of &oat 22 
That the conditions of partial thrust,.then termination 
of thrust may be,.in fact, a ~ e d ,  the fouo*g analY& , sin&.the equilibrib value of Chis 1.25 appmximately, 
is pertinent: it followa ,that: 
It is well established in rocket motor desigri that the 36; (8) An= 1.25A8 
f ' t ~ ~ e ~ ~ ~  seg net *st ior an instant is thus m ,  but local sonic 
be expressed as: velocity soon occurs at the forward end of tke motor 
structure 2. Since the forward end throat 22 is larger 
(1) F = S s ~ d s = S s ~ & ~ + S s i ~ d ~ i  4o than the a;ft end throat 8, the reaward thrust is greater 
where: . and thus the.motor structure will decelerate. Or, stated otherwise, it will accelerate away from the payload struc- 
F: thrwt ture 1, 
p: local pressure Xt .ti be observed that k 'the combustion stops at this 
pi: inside pressure stage and if later the propellant should reignite, there is 
p,: external pressure 45 no intluence on the separated payload structure 1. 
S: surface area l t  will ,be apparent from the abqve description that 
Si: inside surface area many modifidations are possible in the light of the above 
So: outside surface area teaching. It is, therefore, to be understooil that within 
If the thrust coefficient is defiaed as the ratio of thrust 
to the product of chamber pressure and throat area, it 
is established that: ' 
where: 
As: cross sectional area of the throat 5 
&: cross sectional area of the motor chwber structure' 
&: cross sectional area at disuharge end of the p e e  
structure 4 
CF: thrust d c i e n t  
e: expamion ratio 
'the scope of the appended claim the invention may be 
practiced otherwise than as specifically described herein. 
We claim: - .  . , .  
1. A rocket vehicle comprising: me- defining a 
rocket m~ to r  chamber conhidng a solid propellant; a 
first t h a t  crf smaller area, a second ;throat of inter- 
mediate area, and a. third &rat of larger area, the first 
and second threat communiaating,with and directed cear- 
w a r d ~  from said rocket mato8 chamber, the third throat . 
dso ~:ommnniCathg wi& rocket motor chamber and 
directed forwardly therefrom; said first, second, and third 
throats 'being operable in sequence b impart 'respectively 
an initial.mapr forward tlmst, a subdequmt minor' for- 
,.ward thrust, and a final seasward &rust t@ 's&d rocket 
motor. I 
4 2. A rocket vehiole crmrprising: means defining a e":x - 
a 85 rooket m t o t  .chamber cmtahing a solid pbpellmt; a 
fist  throat of smaller arew a second 4thrqat;' of in&' p,: chamber pressure mediqte. area,. and! a .third &mat of larger are% tsle^ f i ~ t  
At the instant that the no&e strumre is separated-the and second thnat comPhunicrting with' an$ Mectii re&>, 
throat 8 (having a &oss-section& area A81 becomes e&c- wardlyIfromm said rocket motor chakkr, b e  third thioat 
tive, and the thrust produce&k: . , .  . also comztl~nicating witti said rocket motor chamber and 
(3) F2=%pcA8 directed 'forwardly therefrom sifd first throat being o p  
where erabIe to. impart an initial forward ttirust to said rocket 
(4) c,,, =L&-&-& [SAdWe -iddA6p motor; a :&st remote command means for terminating 
An % Aa r ' p b  E#'] n opratis 'of saidl'&sf throat and ciusrng operation of 
5,122,008 
5 6 
said second throat, said second throat being operable to produce a major initial forward thrust; a second nozzle 
impart a minor forward thrust to said rocket motor; and means for said motor chamber structure to produce a 
a second remote command means for causing operation minor forward thrust; means responsive to remote com- 
of $aid third throat to cancel the said minor forward mand to inactivate said first nozzle means and activate 
thrust and producc a rearward thrust to said rocket motor. 6 said second nozzle means; a third nozzle means for said 
3. A rocket vehicle, comprising: a payload structure; motor chamber structure to produce a rearward thrust 
a rocket motor structure; a nozzle structure; a first and on said motor chamber structure thereby to effect de- 
second remote command means connecting respectively celeration thereoP; a payload structure initially connected 
said nozzle structure to said motor structure, and said to said motor chamber structure; and means responsive 
motor structure to said payload structuye; a minor throat 10 to remote command for disconnecting said motor cham- 
formed in said nozzle structure; an intermediate throat ber structure from said payload 'structure prior to activa- 
formed in the rearward end of said motor structure ad- tion of said third nozzle means. 
jacent said nozzle structure; and a major throat formed 
in the forward end of said motor structure and initially References Cited in the file of this patent 
covered by said payload structure; said minor throat 16 UNITED STATES PATENTS 
being operative to produce an initial forward thrust to 2,596,644 Bradford et al. ,,-,,,-- May 13, 1952 said structures; said first w d  second remote control mcans 
being operable in sequence to cause operation of said 2,655,105 Hansche --------- - ---- Oct. 13, 1953 
intermediate and major throats; thereby to produce in 2,809,584 Smith ---,---,----,,-, Oct. 15, 1957 
sequence a reduced folrward thrust to said payload and 20 2,952,972 ICimmel et ---------- Sept. 20s 1960 
rocket motor structures and a final rearward thrust to said 29959,129 Warren ---------------- NOv. 1960 
motor structure. 2,996,316 Terhume ,,--------,--, Aug.15,1961 
4. A rocket vehicle structure, comprising: a rocket 3,029,734 Allenson -------------- AP~.  17, 1962 
motor chamber structure containing a, solid propellant; 3,032,356 Botsford --------------- May 1, 1962 . 
a first nozzle means for said motor chamber structure to %i 3,040,517 Ryden et al. ------------ June 26, 1962 


Apparatus and method for control of a solid fueled rocket vehicle Patent

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