US2791962A

US2791962A - Rocket igniter

Info

Publication number: US2791962A
Application number: US280720A
Authority: US
Inventors: Terce Paul Joseph Jean
Original assignee: S E R A M SOC
Current assignee: S E R A M SOC; SOCIETY S E R A M
Priority date: 1951-04-10
Filing date: 1952-04-05
Publication date: 1957-05-14
Anticipated expiration: 1974-05-14
Also published as: NL84466C; CH302185A; NL168481B; BE510197A; FR61564E; DE952421C; GB717185A; LU31362A1

Description

May 14, 1957 P. J. J. TERCE 2,791,962

ROCKET IGNITER Filed April 5, 1952 17314-4 7-02: 7,4 amine; Jaw 724%? ROCKET IGNITER Paul Joseph Jean Terc, Paris, France, assignor to Society S. E. R. A. M., Boulogne sur Seine, France Application April 5, 1952, Serial No. 280,720 Claims priority, application France April 10, N51

6 Claims. (Cl. 102-49) Rocket-motors are already known which comprise a hollow body for receiving a combustible propellent charge formed by a plurality of powder grains extending longitudinally throughout said body and arranged in spaced relation from one another, whereas an electrically operable igniter is arranged at the forward end of the motor body and separated from the powder grains by a transverse partition provided with apertures or flash-holes.

An object of the present invention is a rocket igniter adapted to project gas jets of high temperature through the flash holes with a substantially definite energy and at predetermined points of the combustible propellent charge to allow the ignition of said charge to be obtained in a symmetrical relation with respect to the size and shape of the charge.

Another object of the invention is to provide means facilitating control of the projection of the igniting hot gases generated by the igniter to allow them to be projected only when a predetermined pressure is reached in the igniter.

Still another object of the invention is to provide means preventing non-ignited powder from being thrown out of the igniter by hot gas-jets.

A further object of the invention resides in a perfectly symmetrical arrangement of the igniter with respect to the axis of the rocket and to the propellent charge.

With these objects in view, the rocket motor according to the invention comprises an electrically operable igniter formed by a flat cylindrical metal box or hollow body completely filled with a compressed igniting charge and comprising a cup-like lower part the bottom of which is applied against the front face of the powder grains and provided with flash holes arranged adjacent the voids provided between the grains, respectively, and symmetrically with respect to the voids, and a cover into which the cup is forced and the edge of which is bent outwardly and backwardly to be tightly and elastically forced into the forward end of the hollow metal box to form a head therefor, means for temporarily obturating the flash holes to allow the same to be opened only when the gas pressure in the igniting box has reached a predetermined value, and two electrical squibs arranged inside the igniting box symmetrically with respect to the motor axis and to the flash holes.

By way of example an embodiment of an ignition device according to the invention is described hereafter and shown in the annexed drawing:

Fig. 1 illustrates a vertical section of the device, which is shown in an elevation.

Fig. 2 is a cross-section taken along line l.IlI of Fig. 1.

The rocket motor illustrated in Fig. 1 includes a combustible propellent charge constituted by a block of powder 1 provided with longitudinal channels so that the transverse section of said block is in the shape of a cross as indicated in Fig. 2. This block is housed in the hollow cylindrical body 2 in which it is maintained in position nited States Patent Patented May 14, 1957 by means of a plurality of

wedges

3, 3. At the forward end of the body is arranged a flat cylindrical metal box 4 containing the igniter. The box 4 consists of a cuplike part or member 5 having an upright wall and a bottom Wall, the latter being applied to the adjacent front face of the block 1 and has flash holes or perforations 6, 6, 6", 6" arranged between the ribs or legs of the cross-shaped block 1. This cup-like part 5 is forced into a cover 7 having its edge bent outwards and backwards, to present a U-shaped peripheral flange 8 facing said body end and abutting the inner wall defining said hollow body 2, which flange is forced into the fore end of said body and constitutes an obturator therefor. In addition, this arrangement supplies a good centering of the ignition box 4 relative to the rocket body 2. Two electric squibs 9, 9' are symmetrically arranged with respect to the axis of the body. These igniters may be, for instance, set on a metal bracket 10 welded at 11 to and centrally of the cup-like part 5, the ends of the bracket carrying

small retaining tubes

12, 12 made of a plastic material through which pass for accommodation the feeding or

ignition wires

13, 13 of the igniters, the wires crossing next the bottom of the cup and the body of the rocket motor.

The box 4 is entirely filled with compressed ignition charge'so that the density of said charge remains unchanged after long transport and storage. Further the box is constructed to be gastight. For this purpose, the flash holes 6, 6', 6", 6", are covered, as shown in Fig. 2, with 'a' gauze 14 impregnated with a suitable varnish. According to an alternative form the holes are merely partly cut through to form breaking lines whereby the complete opening thereof is caused after ignition due to the pressure of the gases generated by the combustion of the ignition charge.

It can thus be seen that there has been provided according to this invention a rocket motor, which is characterized by a substantially cylindrical hollow body open at at least one end thereof, a substantially flat cylindrical closure box for receiving an igniting charge seated within the open end, the box including a cup-shaped member having a bottom wall and an upright wall, the cup-shaped member opening toward the open end of the body, a covermember for the cup-shaped member and provided with U-shaped peripheral flange means facing the body end, the peripheral flange means abutting against the inner wall defining the hollow body and embracing the upright wall of the cup-shaped member to thereby close the box, the bottom of the cup-shaped member being provided with perforations directed toward a propellent charge when placed in the hollow body adjacent the box, and electrical igniting means mounted on the bottom of the cup-shaped member and including ignition wire means and electric squib means symmetrically arranged with respect to the axis of the hollow body, and retaining tube means for accommodating the ignition wire means and extending from the squib means therethrough into the hollow body for contact with the propellent charge when contained therein.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. In a rocket motor; a substantially cylindrical hollow body open at at least one end thereof, a powder grain propellent charge arranged in said hollow body and provided with longitudinal channels, a compressed igniting charge, an electrically operable igniter formed by a flat cylindrical metal box completely filled with said compressed igniting charge and comprising a cup-like lower part the bottom of which is applied against the end of said propellent charge and is provided with flash liol'es arranged adjacent said channels provided in said charge, respectively,,and symmetrically withsrespect to. saidchannels; acover intdwhich said cupalike partris-forcedand. theredge'of which is bent outwardly and backwardly to:

betightly and-elastically forced into-the-open endof. the hollow body to form the headthereof, means for temporarily obturating saidi flash holes to allowsamewtobe opened. only when the: gas pressure in. the igniting box:

has reached. a predetermined value, and. two electrical squibs arranged inside: said. igniting, box-1 symmetrically with. respect to' the axis. of. the motor; and. to the flash holes.

2. Ina rocket.motor;;a substantially cylindricalhollow body open. at at:- least: one end: thereof, a; powdengrain.

propell'ent charge" arranged im said hollow body" and. pro.- vided with longitudinal channels; a. compressed. igniting charge, an. electrically operable: igniter formed. by a; flat-- cylindrical. metal box completely filled with. said. com..- pressed igniting charge and comprisingat. cup-like lower. part the bottom. of which. is applied against the end. of said propellent charge and provided with; flash holesarranged. adjacent to the: channelsprovidcd insaid charge,

respectively, and symmetrically with respect'to said chain nels', a cover into which. said cup-like part is;forced and. the edge of which is bent outwardly and-backwardlgtobe'tightly and; elastically forced into the open end; of the hollow body' to form the; head thereof, means for: tern porarily' obturating' said flash. holes to. allow' same; tobe opened only when the gas-pressure irrtheigniting: box.

has reachedv a predetermined value, two. electrical. squibs. arranged inside. said igniting: box. symmetrically with re-- spec: to the motor axis and to the. flash holes; a metallic bracket welded to the: bottom oi the cup-like'part' of the:

igniterbox, insulating tubes attached. to theendsof? said;

of said propellentcharge and provided: with flash holes arranged; adjacent thechannels provided in said charge, respectively, and symmetrically'with respecttosaid chant n'els, and a cover into which said cup-like part is forced and the edge; of which: is bent outwardly: and backwardly to betightly and elastically forced intothe forward end of the hollow body to form the head therefor, a gauze impregnated with a varnish. temporarily obturating said flash holes to allow some to be opened only when the gas pressure in the igniting box has reached a predetermined value, and. two electrical squibs arranged inside said igniting box symmetrically with respect to the axis of said motor and to the flash holes.

4. In a rocket. motor; a combustible propellent chargecomprising a powder block having a cross-shaped transverse section, a hollow body open at at least one end wherein said block is: arranged longitudinally, a compressed igniting charge, an electrical igniter formed by a flat cylindrical metal box completely filled with said compressed igniting charge and constituted by a cup-likelower part the bottom of which is applied against the end of said powder block and provided with four flash holes arranged symmetrically'with' respect to the axis of the motor, a cover into which said cup-like part is forced and the edge of-whicli is bent outwardly andbackwardly to be tightly and elastically forced into the open end of the hollow body to form the head thereof, means for temporarily obturating said flash holes to allow same to be opened only when the gas pressure in the igniting box has reached a predetermined value, a bracket fixed to the bottom of the: cup-likepart of the igniting box, two insulating tubes carried by the ends of said bracket, two feeding'wires arranged inside the hollow body and entering the igniting'box and'passingthrough said tubes, and two electrical:squibs:connected to said'wires, respectively, and arranged symmetrically with respect to said axis ofthe motor-and to thefl'ash holes.

5. A rocket motor comprising a substantially cylindrical hollow body open at at least one end thereof, a substantially flat cylindrical closure box for receiving an igniting charge seated within said open end, said box including a cup-shaped member having abottom wall and an upright wall, said cup-shaped member opening toward said open end of said body, a cover member for said cup-shaped member andprovided with U-shaped peripheral flange means facing said body end, said peripheralfiange means abutting against the inner wall defining said' hollow body and embracing said upright wall of said cup-shaped'membertothereby close-said box, the bottom of said cup-shaped member being provided with perforations directedtoward apropellent. charge when placed in'said' hollow body adjacent said box, and electrical igniting means mounted on said bottom wall ofsaid cup-shaped member'and including ignition wire means, and electric squib means symmetrically arranged with respect to the axis of said hollow body, and retaining tube means for accommodating said ignition wire means and extending from said squib means therethrough into said hollow'bod'y'forcontact with said-propellent charge when contained therein.

6. A rocket igniter for insertion in the open end of arocket motor to be filled with a propellent charge, comprising a closure box for containing the igniting charge, said box including a cup-shaped member having a bottom wall and an upright wall and opening toward the open end of said motor, a cover member for said cup-shaped member and provided with laterally extending U-shaped flange means to respectively engage said upright wall of said cup-shaped member for closing-the latter and to abut against a: wall of said rocket motor defining said open end, electric squib means having wires, bracket means on the bottom of" said' cup-shaped member for carrying said electric squib'rneans, and wire retaining tube means, whereby said wires from said squib means extend through said tube means and said bottom wall of said cup-shaped member into said propcllent charge of said rocket motor, said bottom wall of said cup-shaped member being provided with perforations equi-distantly spaced from the center of said bottom wall and directed toward said propellent charge when contained in said rocket motor.

References Cited. in the file of this patent UNITED STATES PATENTS 1,812,010 McBride June 30, 1931 2,469,350 Lauritsen May 10, 1949 2,515,048 Lauritsen July 11, 1950 2,685,837 Sage et-al. Aug. 10, 1954 FOREIGN PATENTS 16,712 Great Britain of 1915 580,866 Great Britain Sept. 23, 1946 922,209 France Jan. 27, 1947