Aerojet Reusable Rocket Engine Preburners Excel in Tests

SACRAMENTO, Calif., June 8, 1999 -- Aerojet last week successfully tested fuel- and oxidizer-rich preburners as the first step in the development of a highly reusable rocket engine for future U.S. Air Force applications.

The key feature of Aerojet's preburners is that they generate both fuel-rich (gaseous hydrogen) and oxidizer-rich (gaseous oxygen) turbine drive fluids to power the engine's turbopumps. Dividing the work between two turbines significantly reduces the turbine inlet temperature. And using the entire propellant flow as the turbine drive fluid provides cooler drive gases that substantially reduce wear and tear on the turbines, which is vital for reusable engines.

"These initial tests demonstrated the solid engineering behind our preburners and their significance in the realization of long-life engines, " said Bob Harris, Aerojet vice president, Strategic and Space Propulsion.

Under the U.S. Air Force's Integrated Powerhead Demonstration Program, Aerojet is developing the preburners together with a main combustion chamber and a nozzle assembly that utilizes Aerojet's formed platelet technology.

Last week's tests conducted at Aerojet's cryogenic engine component development facility validated the preburners' ignition, reliability and throttleability over a range of fuel-oxidizer ratios and power settings. This data will also be used later to establish the optimum propellant flowrates needed for the engine's start sequence.

"Our preburners use higher propellant mass flows at lower temperatures. They achieve the same results as other engine systems that use lower, fuel-rich-only propellant mass flows at higher temperatures, a less efficient method with built-in dangers when used to drive liquid oxygen turbopumps," said Eric Motz, Aerojet's program manager for the project.

Aerojet's preburners eliminate a potential fire hazard by directing oxidizer-rich propellant flow to drive liquid oxygen turbopumps. So, even if a turbopump seal leaks, there is no fuel to burn with the oxygen, a situation that is possible with fuel-rich preburners that direct fuel-rich streams to liquid oxygen turbopumps.

Aerojet, a GenCorp company, is a world-recognized aerospace and defense leader principally serving the space electronics, missile and space propulsion, and smart munitions and armaments markets. Aerojet's Web site address is http://www.aerojet.com.

-- end --