The requirements of the Space Shuttle Bipropellant RCS Engine Technology contract and the scheduled contract effort are presented herein. The requirements included an engine concept scalable from 400 to 1100 lbf, with a 100 mission life employing N204/MMH propellants. Emphasis is placed on reusability and minimum post-flight servicing. The engine components are reviewed and their selection supported by tradeoff analyses, thrust chamber firing test data, materials test data and metallurgical evaluations. The materials test data indicate that the proposed silicide-coated columbium chamber and uncoated columbium injector have the potential of meeting the mission life consistent with the Isp goals. The engine valve trade studies resulted in the selection of a torque motor-operated bipropellant valve configuration. “Fuel vortex film vortex film film cooling” of the insulated chamber is described, together with the fuel vortex film cooling scaling parameter and its verification by test data to a thrust level of 5500 lbf. The steadystate performance goal of 295 s Isp with a maximum insulated chamber temperature of 2200 F has been demonstrated with that approach to chamber film cooling. Engine thermal analyses are presented. The correlation of predicted and observed pulse mode operation confirms the basic engine transient analytical model. The results of engine rain, sand and dust, salt spray testing, and no post-firing servicing indicate that minimum engine ground servicing will be achieved. The test data to date, the component configurations, and materials selected indicate that all bipropellant RCS requirements and goals can be met.
