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SP-432 The Space Shuttle At Work

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Bulk alone is a scant clue to differences in these three engines. The F-1 was in Saturn V's first stage, used kerosene, and had to work for minutes; the second- and third-stage J-2 used hydrogen, also had a short design life. Shuttle engines (SSME), vastly more efficient, last for 5 5 flights before overhaul.

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