US3048970A

US3048970A - Plastic nozzle plate for missile motors

Info

Publication number: US3048970A
Application number: US769517A
Authority: US
Inventors: Stephen H Herzog
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-10-24
Filing date: 1958-10-24
Publication date: 1962-08-14
Anticipated expiration: 1979-08-14

Description

Aug. 14, 1962 s. H. HERZOG PLASTIC NOZZLE PLATE FOR MISSILE MOTORS Filed Oct. 24, 1958 INVENTOR. STEPHEN H. HERZOG ilnited rates Patent U 3,048,970 PLASTIC NOZZLE PLATE FOR MISSILE MOTORS Stephen H. Herzog, China Lake, Califi, assignor to the United States of America as represented by the Secretary of the Navy Filed Oct. 24, 1958, Ser. No. 769,517 3 Claims. (Cl. 6035.6) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to rocket motors; more specifically, it relates to improvements in discharge nozzles.

Steel discharge nozzles for rockets have been used successfully in the past. The use of higher energy propellants, however, brought about the use of erosion-resistant inserts in the constricted part of the nozzle where the erosion is greatest. Some of the present propellants are so energetic that the steel around the insert erodes away during operation of the motor, allowing the insert to be expelled from its seat.

Further, the steel nozzles used in the past have been fairly heavy of necessity, due to the rather substantial construction required.

It is therefore an object of this invention to provide a nozzle having an erosive-resistant insert which will not be expelled during operation of the motor.

A further object is to provide a nozzle which is considerably lighter than existing steel ones, while having a nozzle insert which will not be expelled during operation of the motor.

With these and other objects in view, as will hereinafter more fully appear, and which will be more particularly pointed out in the appended claims, reference is now made to the following description taken in connection with the accompanying drawings in which:

FIG. 1 shows a plan view of the nozzle plate assembly;

FIG. 2 shows an elevational crom-sectional view taken along line 2-2. of FIG. 1, and

FIG. 3 shows a cross-sectional plan view taken along line 33 of FIG. 2.

Referring now to the figures, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown a nozzle plate 11 having a plurality of exit ports as shown, each port having a beveled surface 12. The plate 11 has a raised center portion 13 on the side opposite to the side shown in FIG. 1 which is provided with a threaded hole extending through the raised portion and plate; plate 11 is further provided with a circumferential skirt portion 14 made integral therewith. A disk 15 is positioned inside the skirt portion in contact therewith and is provided with a plurality of exit ports corresponding to and in alignment with the ports in plate 11, the ports of disk 15 having beveled surfaces 16 so as to form a smooth continuous surface with the beveled surfaces 12 of plate 11. Disk 15 is provided with a well, as shown, to receive the raised portion 13 of plate 11 and to remain in contact therewith. A threaded hole extends from the bottom of said Well to the other side of disk 15.

Tubular inserts 17 are provided in the ports of disk 15, said inserts having beveled surfaces 18 which form a smooth continuous surface with the

beveled surfaces

12 and 16 of plate 11 and disk 15, respectively. Inserts 17 are also provided with inner beveled surfaces at the end opposite to the end having beveled surfaces 18. The parts of disk 15 are further provided with beveled surfaces 19 3,943,973 Patented Aug. 14, 1962 at the end opposite to the end having beveled surfaces 16.

Rupture diaphragms 21 are provided in the hollow inserts to seal the openings until the motor is ignited, whereupon they are ruptured.

Plate 11, its skirt portion 14, and raised center portion 13 are conventional and made of steel.

The inserts 17 are highly resistant to erosion and are made of graphite, a refractory metal, or certain metal oxides, all well known for their resistance to erosion.

The disk 15 is made of a thermosetting resin, preferably a phenolformaldehyde resin which incorporates up to 70% of a filler. The filler is preferably chopped glass or asbestos though other materials could be used. The preferred resin is one having a low degree of polymerization. The filler may be glass, asbestos fibers or metal particles and filaments, though asbestos or glass fibers are preferred.

In practice, the steel plate 11 is first machined; the plastic portion is made separately and press fitted into position.

The plastic disk 15 is made by positioning the erosionresistant inserts in a suitable mold, pouring in the resin to which the filler has been added and blended, and heat treating the mold to cure the resin. The rupture diaphragm is thus molded in place in this operation. Alternatively, the steel plate 11 and integral skirt 14 may be used as part of the mold and the disk 15, the inserts 17 and blowout diaphragms 21 molded in place.

In assembling a rocket motor incorporating the nozzle assembly of this invention, the combustion chamber is first loaded with propellant and ignition means, and the nozzle plate assembly is screwed into position at the end of the combustion chamber.

A number of the instant nozzle plate assemblies have been tested under the same conditions that caused conventional steel nozzle plates to expel their erosion-resistant inserts and no such expulsion was observed.

What is claimed is:

1. An erosion resistant nozzle plate assembly comprising a metal plate having an annular skirt portion on one side thereof and at least one discharge port therein, the walls of each discharge port increasing gradually in diameter from the side of said plate having the annular skirt portion to the opposite side of said plate, a disk of heatresistant plastic material having a diameter equal to the inner diameter of said plate skirt portion fitting within said skirt portion and in contact with said plate, said disk having a number of discharge ports therein equal to said at least one port in said plate and in alignment therewith, the walls of each discharge port in said disk increasing gradually in diameter from a smallest diameter at a point intermediate the two faces of said disk to the outer face thereof, the largest diameter of each discharge port in said disk at the face thereof which contacts said plate being equal in diameter to the smallest diameter of said at least one discharge port in said plate, a tubular nozzle insert of erosion-resistant material imbedded in said disk port Walls at said intermediate point being completely separated from said plate by the material of said disk and having walls coinciding with said disk port walls, whereby a converging-diverging nozzle having smooth surfaces is formed by the beveled surfaces of the aforementioned parts and a heat barrier is formed between the nozzle surfaces and said metal skirt.

2. The device of claim 1 wherein the disk portion is made of a phenol-formaldehyde resin incorporating from about zero to about 70% of a filler selected from the class consisting of asbestos and glass and said insert is made of graphite.

zap same 3. A nozzle plate assembly for rocket motors comprising a steel plate having a circumferential steel skirt and a plurality of exit ports therein each of which has a beveled surface, a heat-resistant rosin disk positioned within said skirt, said disk having a plurality of exit openings in alignment with the exit ports of the steel plate and each opening being provided with a beveled surface, and a tubular erosion-resistant insert embedded Within the Walls of each of the exit openings of said disk, each insert being insulated from said steel plate by the resin of said disk and having a beveled surface, and the beveled surface of each exit opening of said disk merging with the beveled surfaces of its associated insert and exit port to provide a smooth continuous surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,755,620 Gillot July 24, 1956 2,835,107 Ward May 20, 1958 2,849,860 Lowe Sept. 2, 1958 2,939,275 Loedding June 7, 1960 2,958,184 Sanders Nov. 1, 1960 2,968,919 Hughes et a1 Jan. 24, 1961 2,987,874 Nicholson June 13, 196 1 FOREIGN PATENTS 1,135,050 France Apr. 23, 1957 757,890 Great Britain Sept. 26, 1956 l