US3254603A - Hypergolic igniter - Google Patents

Description

June 7, 1966 B. B. GOULD HYPERGOLIC IGNITER Original Filed March 8, 1961 IN VEN TOR 5527 5. 601/40 BY I A TTOB/VEVS United States Patent 3,254,603 HYPERGOLIC IGNITER Bert B. Gould, Berkeley, Calif., assignor to Ordtech Corporation, a corporation of California Continuation of application Ser. No. 94,239, Mar. 8, 1961. This application Feb, 4, 1965, Ser. No. 431,779 6 Claims. (Cl. 102-70) This invention relates to a method and apparatus for igniting miniature solid propellant rockets.

This application is a continuation of my copending application Ser. No. 94,239, filed March 8, 1961, now abandoned and entitled Hypergolic Igniter.

The ignition of large solid propellant rockets presents no particular problems, but the ignition of miniature rockets involves serious problems. For one .thing, the physical sizes are so small that conventional ignition systems cannot be scaled down sufliciently. Further, the burning time of miniature rockets is so short that substantially uniform ignition must be obtained instantly throughout the rocket in order to secure eflicient use of the propellant and to prevent excessive tail burning. The miniature rockets to which this invention relates are extremely small in size wherein the rocket has a diameter of about one-tenth inch, and a length of one and onehalf inches. Ordinarily, a central burning port of about 0.05 is employed with a nozzle throat diameter of only 0.03". Thus, the ignition system must be extremely small and be adapted for insertion through a throat of only 30 mils diameter.

In accordance with the present invention, it has been found that such miniature rockets can be satisfactorily ignited employing a hypergolic fluid. Preferably the grain of the rocket is first coated with a pyrotechnic mixture, it being understood, of course, that the hypergolic fluid which is selected is one which will ignite spontaneously with the pyrotechnic mixture, if used, or if not used, with the grain itself. Typical hypergolic combinations of a liquid or gas and a solid are red fuming nitric acid and phenylenediamine, hydrogen peroxide and red phosphorus, chlorine trifluoride and nitrocellulose.

A pyrotechnic mixture, such as black powder, Sb S and Ba (N09 boron and KNO or lead monoresorcinate and KClO may be mixed with nitrocellulose as a binder and used as a coating. Before drying, the surface may be dusted with the solid component of the hypergolic combination. Alternatively, the solid component may be incorporated directly into the pyrotechnic mixture.

Various methods can be used for bringing the hypergolic fluid into contact with the pyrotechnic material. Small tubes may be employed which can be inserted through the throat of the motor and which inject the liquid directly into the burning port. The tube need not enter the port directly but a spraying device can be employed to spray the fluid through the nozzle into the port. According to one embodiment of the invention, the nozzle of the rocket is coated with a pyrotechnic material, and the ignition of this coating induces ignition of the grain. Further, the hypergolic liquid may be contained within the port itself in a suitable envelope or capsule and ignition effected merely by rupturing the capsule.

In the drawings forming part of this application:

FIGURE 1 is a sectional view of a rocket motor wherein liquid is injected directly into the port;

FIGURE 2 is a sectional view of a rocket motor wherein a hypergolic liquid is sprayed externally of the port; and

FIGURE 3 is a sectional view of a rocket motor wherein the hypergolic liquid is contained within one or more capsules within the motor.

In all figures, 5 represents the casing of the motor, said casing having a propellant grain 7 therein which is coated 3,254,603 Patented June 7, 1966 with a pyrotechnic mixture 9. The motor is also provided with a nozzle assembly 11.

In the embodiment of the invention shown in FIGURE 1 a source of a hypergolic liquid under pressure 13 is provided which is connected by means of the valve 15 to a manifold line 17 which terminates in a branch line 19. Since the rockets of the present invention are ordinarily packaged in a cluster and fired in a salvo, ordinarily a plurality of branch lines 19 would be connected to the manifold line 17 although only one branch line is shown. Branch line 19 terminates well inside of the port 10 as at 21. In order to fire the rocket motors, it is only necessary to actuate the valve 15 releasing the hypergolic liquid into the ports of the rockets.

In FIGURE 2 an embodiment of the invention is shown wherein a sprayhead 23 or similar injection device is located some distance aft of one or a plurality of the rockets. The inner surface of the nozzle is coated with a pyrotechnic material 12 which extends into-the burning port 10 and connects with the pyrotechnic material 9. Sprayhead 23 is connected to a pressurized source of a hypergolic fluid, not illustrated. Here it is only neces sary to release a cloud or spray 25 of the hypergolic fluid and the fluid ignites the mixture 12 which will propagate the flame to the material 9 and thus ignite the rockets. In many instances it is unnecessary to coat the nozzle area since there will be suflicient penetration of the fluid to ignite the rocket.

In FIGURE 3 an alternate form is shown wherein a hypergolic fluid is contained within a frangible capsule- 27. In order to fire the rocket, it is only necessary to insert a needle-like object 29 through the throat of the rocket and rupture the capsule 27. This can be done either by moving the motor backwards over a fixed mandrel or by holding the motor still and inserting the mandrel into the cavity.

It is obvious that any liquid, vapor and aerosols of solid or liquids may be employed providing they are hypergolic with the pyrotechnic and/or propellant compositions employed.

I claim:

1. An igniter for a miniature solid propellant rocket. comprising in combination:

(a) a solid propellant rocket having a discharge nozzle and a solid propellant grain with a central burning port;

(b) a source of a hypergolic fluid external of said discharge nozzle;

(c) a coating of a pyrotechnic mixture on the walls of said burning port, said mixture being hypergolically sensitive with said fluid; and

(d) means for injecting said fluid from said source onto said coating.

2. The device of claim 1 which includes a small tube in the port of the rocket through which the hypergolic fluid is injected into the port.

3. The device of claim 1 wherein the inside surface of the rocket nozzle is coated with a pyrotechnic material.

4. The device of claim 1 which includes a frangible container within the port of the rocket containing the hypergolic fluid and means for rupture of said frangible container.

5. An igniter for a miniature solid propellant rocket comprising in combination:

(a) a solid propellant rocket having a discharge nozzle and a solid propellant grain with a central burning port in alignment with said discharge nozzle;

(b) a separate source of hypergolic fluid;

(c) a coating on the walls of said burning port formed of a solid pyrotechnic mixture which is hypergolically sensitive with said fluid;

3 (d) means for release of hypergolic fluid from said source for engagement with said coating; and (e) a coating of a pyrotechnic material as a coating on the rocket nozzle. 6. A device as claimed in claim 5 in which the hypergolic fluid is introduced into engagement with the coating of pyrotechnic material on the rocket nozzle.

4 References Cited by the Examiner UNITED STATES PATENTS 2,959,001 11/1960 Porter 1027O 2,974,484 3/196-1 Cooley 102-865 BENJAMIN A. BORCHELT, Primary Examiner. G. H. GLANZMAN, Assistant Emminer.

Claims (1)

1. AN IGNITER FOR A MINIATURE SOLID PROPELLANT ROCKET COMPRISING IN COMBINATION: (A) A SOLID PROPELLANT ROCKET HAVING A DISCHARGE NOZZLE AND A SOLID PROPELLANT GRAIN WITH A CENTRAL BURNING PORT; (B) A SOURCE OF A HYPERGOLIC FLUID EXTERNAL OF SAID DISCHARGE NOZZLE; (C) A COATING OF PYROTECHNIC MIXTURE ON THE WALLS OF SAID BURNING PORT, SAID MIXTURE BEING HYPERGOLICALLY SENSITIVE WITH SAID FLUID; AND (D) MEANS FOR INJECTING SAID FLUID FROM SAID SOURCE ONTO SAID COATING.

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