Enhanced liquid oxygen-propylene rocket engine

A liquid rocket engine, comprising:

• a combustion chamber configured to receive liquid oxygen and liquid propylene for combustion;
• a first propellant feed line configured to carry the liquid oxygen from a first propellant tank to a first main valve;
• a second propellant feed line configured to carry the liquid propylene from a second propellant tank to a second main valve;
• an injector assembly configured to receive the liquid oxygen and the liquid propylene from associated ones of the first and second main valves and inject the liquid oxygen and the liquid propylene into the combustion chamber, the injector assembly formed into a single body by an additive manufacturing process and comprising:
• a fuel cavity;
• an oxidizer cavity that forms a quasi-toroidal shape around the fuel cavity;
• two or more propellant feed stubs forming tube structures tapered outwards from a first face of the injector assembly and formed into the single body of the injector assembly by the additive manufacturing process, wherein the two or more propellant feed stubs are each mechanically swaged or flared to mate with a compression-type fitting in a metal-to-metal seal for attachment to an associated propellant feed line routed from the associated ones of the first and second main valves, with at least a first stub configured to carry the liquid propylene to the fuel cavity and at least a second stub configured to carry the liquid oxygen to the oxidizer cavity;
• and
• a plurality of injection features comprising a plurality of apertures in a second face of the injector assembly opposite the first face of the injector assembly, each of the fuel cavity and the oxidizer cavity feeding a corresponding subset of the plurality of apertures, with ones of the plurality of injection features configured to inject the liquid oxygen and the liquid propylene into the combustion chamber for combustion;
• wherein the first propellant feed stub extends outward from a central position of the first face of the injector assembly, and the second stub extends outward from the first face of the injector assembly in a position offset from the central position, and flow passages of the injector assembly are sized to account for a change in density of using densified propylene cooled below 25° C. as the fuel and liquid oxygen as the oxidizer.

A method of manufacturing a rocket engine propellant injection apparatus, the method comprising:

• forming an injector assembly into single body by an additive manufacturing process, wherein the single body of the injector assembly comprises a fuel cavity and an oxidizer cavity that forms a quasi-toroidal shape around the fuel cavity;
• forming at least a first propellant feed stub into a first face of the single body and tapering outwards from a central position on the first face of the single body by the additive manufacturing process to provide a first channel to carry fuel to the fuel cavity;
• forming at least a second propellant feed stub into the first face of the single body and tapering outwards from a position offset from the central position on the first face of the single body by the additive manufacturing process to provide a second channel to carry oxidizer to the oxidizer cavity;
• forming a plurality of propellant injection features into the single body by the additive manufacturing process comprising apertures in a second face of the injector assembly opposite the first face of the injector assembly, and sizing flow passages of the injector assembly to account for a change in density of using densified propylene cooled below 25° C. as the fuel and liquid oxygen as the oxidizer;
• and
• attaching a first compression fitting to the first propellant feed stub and a second compression fitting to the second propellant feed stub in a metal-to-metal seal, the first and second compression fittings each mechanically swaged or flared to couple to associated propellant lines.