Abstract: This invention relates to a passive self-contained auto ignition system for a hydrogen-oxygen fueled rocket engine. When the fuel for the engine is turned on, the gas pressure in the inlet tube 1 can be used to heat a small portion of the hydrogen in a resonance tube 4 and inject hot hydrogen into the combustion chamber 11 to ignite the hydrogen-oxygen fuel mixture. Once the ignition has started, the pressure in the combustion chamber changes the pressures in the resonance cavity 3, which then shuts off the resonance tubes' heating ability and so shuts off the ignition. If the fuel supply is shut off the engine is turned off and can be restarted by turning the hydrogen-oxygen supplies back on causing the resonance tube to re-ignite the engine.

Abstract: There is disclosed in combination with a solid fuel-propellant grain 24 having an axially extending aperture 26, particularly of a hybrid rocket motor, an oxidizer inlet 20 at one end and a combustion gas outlet 22 at the other end, a tubular oxidizer injector 32 disposed in the inlet and extending axially in the grain aperture. The tubular injector comprises a tube 34 containing a plurality of oxidizer injection orifices 38 in the outer circumference of the tube to discharge fluid streams of oxidizer into the fuel grain aperture for combustion of the fuel grain. Additional oxidizer orifices, e.g. in the form of shower head orifices 44, are disposed in the downstream end of the tube.