Encyclopedia Astronautica

Pratt and Whitney lox/lh2 rocket engine. 290 kN. Development. Isp=472s. Advanced, high-performance upper-stage rocket engine proposed by Pratt & Whitney for both domestic and international launch vehicles.

The 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.

Status: Development.
Unfuelled mass: 500 kg (1,100 lb).
Thrust: 290.00 kN (65,190 lbf).
Specific impulse: 472 s.

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Associated Propellants
  • Lox/LH2 Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

  • Pratt & Whitney Home Page, Web Address when accessed: here.

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