Rocketdyne A-7

The Rocketdyne A-7 was a pump-fed, gas-generator liquid rocket engine, the last of seven closely related versions, A-1 to A-7, of the NAA 75-110 engine that North American Aviation developed for the Army's Redstone missile. Encyclopedia Astronautica records about 370 kilonewtons of thrust at sea level, an engine mass of 658 kilograms and flights between 1956 and 1959, and describes a version for the Jupiter-C test vehicle that burned Hydyne fuel for 140 seconds. When designers of the Mercury-Redstone launch vehicle needed an engine, they chose the A-7 used on the latest military Redstone, and ABMA engineers Hans Paul and William Davidson modified it for crewed flight. They returned it to alcohol fuel with liquid oxygen, because Hydyne had never been used with the A-7 and was more toxic.