Encyclopedia Astronautica

SNECMA, Pratt and Whitney lox/lh2 rocket engine. 230.4 kN. Design 2000. New upper-stage cryogenic engine for the upgraded Ariane-5, the Atlas-5, and other new vehicles.

On 18 February 2000 Pratt & Whitney (USA) and Snecma (France) announced their signing of a memorandum of understanding to jointly design and develop a new upper-stage cryogenic engine for the upgraded Ariane-5, the Atlas-5, and other new vehicles. Rocketdyne had already begun work on the MB-60, slated for first use on the Delta-4 in 2004. Pratt & Whitney and Snecma identified the SPW-2000 as the successor to the now-defunct Pratt & Whitney RL-50, whose early development work was to be transferred to the new engine. The SPW-2000 was to have a thrust comparable to the RL-50's, in the 200-270 kN range. However, the SPW-2000 venture was rejected by ESA on 22 June 2000 due to concerns about competition with European rocket engine manufacturers and problems in setting up a work-sharing agreement among the two companies and their subcontractors. Instead, ESA decided to proceed with development of the all-European Vinci project, initiated in March 1999 but never pursued, to develop an all-cryogenic restartable engine that would boost Ariane-5's capability from 6,300 kg to 11,500 kg into a geosynchronous transfer orbit.

Status: Design 2000.
Thrust: 230.40 kN (51,796 lbf).
First Launch: 2000.

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Associated Countries
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Associated Manufacturers and Agencies
  • SNECMA French manufacturer of rocket engines and rockets. SNECMA, France. More...

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...

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