J-2 (rocket engine)

The J-2 was America's largest liguid hydrogen fueled rocket engine before the Space Shuttle main engines were created (SSME). Five J-2 engines were used in the S-II second stage of the Saturn V rocket. One J-2 engine was used in the Saturn V third stage (S-IVB) and the Saturn IB second stage (S-IVB). There were proposals to use various numbers of J-2 engines in the upper stages of the planned Nova rocket.

Original J-2 specifications

Thrust (altitude): 200,000 lbf (890 kN)
Burn time: 500 s
Specific impulse: 418 lbf·s/lb (4.1 kN·s/kg)
Engine weight – dry: 3,480 lb (1,578 kg)
Engine weight – burnout: 3,609 lb (1,637 kg)
Exit to Throat Area ratio: 27.5 to 1
Propellants: LOX & LH2
Mixture ratio: 5.00
Contractor: NAA/Rocketdyne
Vehicle Application: Saturn IB / S-IVB 2nd stage – 1-engine
Vehicle Application: Saturn V / S-II 2nd stage – 5-engines
Vehicle Application: Saturn V / S-IVB 3rd stage – 1-engine