RL-50

Pratt and Whitney LOx/LH2 rocket engine. Development. Advanced, high-performance upper-stage rocket engine proposed by Pratt & Whitney for both domestic and international launch vehicles.

The RL-50 was an advanced, high-performance upper-stage rocket engine that was being developed by Pratt & Whitney for both domestic and international launch vehicles. The RL-50 was to meet future launch vehicle requirements for increased payload delivery capability, improved launch system operability and enhanced system cost effectiveness. It provided more than twice the thrust of existing upper-stage Lox/LH2 engines. The RL-50 was to have been available in 2003, and incorporated modern technologies to simplify the engine and decrease costs.

Engine: 500 kg (1,100 lb). Thrust to Weight Ratio: 59. Oxidizer to Fuel Ratio: 5.5. Restarts: 2.