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Rocket Engine Evolution

The first American rocket engine to produce more thrust than the 56,000 pounds delivered by the German V-2 (A-4) engine was the Rocketdyne XLR43-NA-1. Initially, this engine developed 75,000 pounds static thrust, but later its power output was improved to 120,000 pounds. The XLR43 was originally developed for the Navaho supersonic cruise missile booster, but the Navaho was never produced. The XLR43, however, was adopted as the powerplant for the Army Redstone missile, the booster that launched the first American space satellite. Later, modified Redstones served as the launch vehicles that lifted Navy Commander Alan B. Shepard Jr. and USAF Capt. Virgil I. Grissom into space in 1961 on their separate suborbital missions aboard the Mercury spacecraft.

The XLR43 then evolved into the Rocketdyne S-3D engine that powered the Jupiter launch vehicle. Following the S-3D was a further development leading to the LR79 rocket engine. It powered the workhorse Thor launch vehicles that, since 1962, have put many smaller payloads into orbit or deep space.

Two more rocket engine combinations contributed much to the nation's space program. The Rocketdyne LR89 booster and the LR105 sustainer engines for the Atlas launch vehicle were used in the Mercury orbital program. The Aerojet-General XLR87 engine powered the first stage of the Titan II booster that put the Gemini spacecraft into orbit. The Titan II was also the booster planned for the abortive Dyna-Soar and Manned Orbiting Laboratory programs.

The Apollo astronauts were launched to the moon atop the gigantic Saturn launch vehicle powered by the 1.5 million pounds thrust F-1 engine. Initial development of the F-1 was begun by the USAF Rocket Propulsion Laboratory in 1955, but in 1958 the project was turned over to NASA, where it continued with great success.

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Related Fact Sheets
Mercury Spacecraft
Gemini Spacecraft
Rocketdyne LR79 Engine
Aerojet-General LR87 Liquid Rocket Engine
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