The reaction control engine (RCE) is being developed for NASA's Marshall Space Flight Center and the Exploration Systems Mission Directorate as a relevant technology that is applicable to the Vision for Space Exploration.

The engine testing validated the operability of a cryogenic LOX-ethanol reaction control engine and ignition system in both steady state and pulse mode operation. It included long duration steady state operations up to 240 seconds and numerous pulse mode operations typical of ascent, on-orbit and re-entry operations.

The testing also included the evaluation of the effects of chamber pressure and mixture ratio variations on the engine, combustion chamber thermal response, and six different pulse duty cycles between 80 milliseconds and ten seconds.

Chamber temperatures were as predicted and uniform in steady state and during pulsing, validating Aerojet's capabilities in controlling the injection and combustion process through the use of proprietary platelet injector design.

"With this testing, Aerojet again demonstrated the value of our unique platelet technology," said Aerojet RCE Program Manager Eric Veith. "The platelet technology distributes the LOX and ethanol propellants in a more uniform manner, thus producing an even mixture ratio, which provides efficient and uniform combustion."

Pulse mode testing was conducted to demonstrate the operability requirements for minimum pulse widths for a liquid-liquid auxiliary propulsion system that used LOX Ethanol. Aerojet worked closely with its suppliers, Moog and Castor Engineering, to develop LOX & Ethanol main injector and igniter valves that operated to meet the required pulse mode operations.

"The successful demonstration of a cryogenic liquid-liquid reaction control engine steady state and pulse mode testing provides the technical foundation for the next step in the LOX-based reaction control system development," Veith said.

Oxygen-based propulsion systems offer several advantages over hydrazine-based systems including improved operability, reduced environmental impacts and the potential for in-situ propellant production beyond Earth's surface.

Aerojet plans to build, hot fire test and deliver three engines for system level testing by NASA during summer 2005 at White Sands Test Facility, New Mexico.

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