Artifact: Rocket Engine, SE-6, Liquid Fuel, Gemini Reentry Control System (RCS)

SE-6 pressure fed bipropellant engines manufactured by ROCKETDYNE Corporation for installation onboard the Gemini spacecraft Re-Entry Control System (RCS). These thrusters utilized a hypergolic propellant combination of Nitrogen Tetroxide (NNH) as the Oxidizer and Monomethyl Hydrazine (MMH) as the fuel. The ablatively cooled pulse-operated engine was rated for a total life span of 96 seconds while providing a vacuum thrust of 23.5 pounds/107 Newtons.

The Thrust Chamber Assembly (TCA) consists of two propellant valves (fuel and oxidizer), injection system, calibrated orifices, combustion chamber and expansion nozzle. The fuel and oxidizer solenoid valves are the normally-closed quick acting type which open simultaneously upon command. The action permits fuel and oxidizer flow into the injector system. The injectors use precise jets to impinge fuel and oxidizer streams on one another for controlled mixing and combustion. The calibrated orifices are fixed devices used to control propellant flow. Hypergolic ignition occurred in the combustion chamber. The combustion chamber is non-regenerative; it is lined with ablative materials and insulation to absorb and dissipate heat and control external TCA wall temperature. When integrated to the Gemini spacecraft, the engine was installed within the RCS module mold line, with the nozzle terminating flush with the outer mold line. A total of (2) sets of eight SE-6 thrusters were paired at approximate radially symmetrical points on the RCS module in a location suitable to execute yaw/roll/pitch maneuvering and attitude control after loss (vehicle separation) of the Equipment Section/Orbit Attitude and Maneuver System (OAMS). The OAMS employed the more potent SE-7 (25, 85 and 100 pound) engines and provided primary attitude control during flight. Firing of the RCS TCA's were commanded via the Gemini spacecraft's Attitude Control and Maneuver Electronics System (ACME).