RS-56 was an American liquid-fueled

rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entir ...

engine, developed by

Rocketdyne Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, in the western San Fernando Valley of suburban Los Angeles, in southern California. The Rocketdyne Division was founded by North American Avia ...

. RS-56 was derived from the

RS-27 The RS-27 was a liquid-propellant rocket engine developed in 1974 by Rocketdyne to replace the aging MB-3 in the Delta. Incorporating components of the venerable MB-3 and the H-1 designs, the RS-27 was a modernized version of the basic design ...

rocket engine, which itself is derived from the Rocketdyne H-1 rocket engine used in the

Saturn I The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to low Earth orbit payloads.Terminology has changed since the 1960s; back then, 20,000 pounds was considered "heavy lift". The rocket's first st ...

and

Saturn IB The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, 43 ...

. Two variants of this engine were built, both for use on the

Atlas II Atlas II was a member of the Atlas family of launch vehicles, which evolved from the successful Atlas missile program of the 1950s. The Atlas II was a direct evolution of the Atlas I, featuring longer first stage tanks, higher-performing engine ...

rocket series. The first, RS-56-OBA, was a booster engine, while the RS-56-OSA was designed for use as a sustainer and produced lower thrust but at a higher

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

References

{{Rocket engines Rocketdyne engines Rocket engines using the gas-generator cycle Rocket engines using kerosene propellant Rocket engines of the United States