Enhanced reliability features of the RL10E-1 engine

Abstract

The RLlOE-1 rocket engine has been partially developed for the United States Air Force during the Atlas Reliability Enhancement Program. This engine is a 22,300 Ibf thrust liquid hydrogen, liquid oxygen, derivative of the RL10A-4-1, and incorporates an improved ignition system and new electromechanically actuated (EMA) valves controlled by an engine mounted Digital Electronic Rocket Engine Controller. The RLlOE-1 electronic control system operates the engine with only six valves (compared to the twelve on the RLIOA-4-1), provides boost phase engine cooldown capability (to avoid cryogenic temperatures at liftoff), and allows implementation of an improved torch ignition system with redundant, modem electronics. Other potential reliability improvements include active engine health monitoring, derated thrust operation, “soft” transients, and improved minimum residual shutdown capability. Although development of the RL10E-1 was not completed, the engine development tests were highly successful in demonstrating engine operation with the full authority, digital electronic control system and fewer valves. Many of the enhanced reliability features have been demonstrated and are directly applicable to other versions of the RL10 engines. Potential “hybrid” engine configurations offer a lower weight and less costly engine, while retaining much of the reliability improvements and other benefits of the RLIOE-1.