Insulated Engine, 100-Pound Thrust

Abstract

The design and test results of an insulated, 100-pound thrust engine capable of delivering high performance, providing long, steady state and pulse mode endurance, and maintaining a low outside surface temperature of 4000 F, are presented. Included are descriptions of the injector designs and insulation materials investigated, plus a discussion of the thermal analysis and test results. Continuous operation in excess of 29 minutes, and start capability in excess of 4900 pulses, have been demonstrated. To allow the use of available chamber materials and coating systems under insulated conditions, the major challenge to the designer was to define an injector design that would provide gas temperatures and performance of a predetermined value. The solution was the development of an unbalanced, 8-element triplet injector having an unequal fuel distribution within each element, capable of providing a specific impulse in excess of 290 pounds at reduced wall temperatures. The design consists of a columbium chamber and nozzle utilizing a silicide coating, a columbium injector, a composite insulation system of aluminum oxide