Gross Mass: 5,040,000 kg.
Empty Mass: 317,000 kg. Thrust (vac): 9,714,000 kgf. Isp: 451 sec. Burn time: 215 sec. Propellants: Lox/LH2Isp(sl): 379 sec. Diameter: 21.6 m. Span: 23.2 m. Length: 49.8 m. Country: USA. No Engines: 18. HP-1Status: Study 1963. Comments: Operational date would have been December 1974. .