Gross Mass: 4,943,000 kg.
Empty Mass: 311,000 kg. Thrust (vac): 10,431,000 kgf. Isp: 410 sec. Burn time: 179 sec. Propellants: Lox/LH2Isp(sl): 345 sec. Diameter: 21.3 m. Span: 21.3 m. Length: 82.3 m. Country: USA. No Engines: 15. M-1Status: Study 1963. Comments: Operational date would have been July 1977. Recoverable stage. 10% plug nozzle. .