Engine Model: HG-3-SL. Propellants: Lox/LH2. Thrust(vac): 1,387.000 kN (311,810 lbf). Thrust(sl): 1,107.100 kN (248,886 lbf). Isp: 450 sec. Isp (sea level): 360 sec. Chambers: 1. Country: USA. Status: Study 1966. Designation for high-performance high-pressure chamber Lox/LH2 engine developed from J-2, fitted with lower-expansion nozzle for sea level use on Saturn INT-17. Technology led to Space Shuttle Main Engines.
HG-3 used on Rocket Stages
HG-3 used on Spacecraft