Gross Mass: 4,213,000 kg.
Empty Mass: 194,000 kg. Thrust (vac): 9,977,000 kgf. Isp: 299 sec. Burn time: 118 sec. Propellants: Lox/KeroseneIsp(sl): 260 sec. Diameter: 21.3 m. Span: 21.3 m. Length: 25.9 m. Country: USA. No Engines: 4. 5 mlbf RP-4Status: Study 1963. Comments: Operational date would have been July 1977. Recoverable stage. 10% plug nozzle. .