Gross Mass: 1,633,000 kg.
Empty Mass: 113,000 kg. Thrust (vac): 1,361,000 kgf. Isp: 426 sec. Burn time: 468 sec. Propellants: Lox/LH2Diameter: 21.3 m. Span: 21.3 m. Length: 21.3 m. Country: USA. No Engines: 4. M-1Status: Study 1963. Comments: Operational date would have been July 1977. Recoverable stage. .