A variant of the first alternative considered in the 1962 nuclear N1 study. This was a 'high thrust' version of the Type A engine - apparently with higher propellant rate, lower specific impulse, and lower engine weight. Due to the very low density of the enormous liquid hydrogen upper stages, these immense vehicles would have been very ungainly (and had interesting stress problems during ascent!)

Manufacturer: Korolev. LEO Payload: 300,000 kg (660,000 lb). to: 220 km Orbit. at: 51.60 degrees. Payload: 27,100 kg (59,700 lb). to a: lunar surface trajectory. Liftoff Thrust: 35,000.000 kN (7,868,000 lbf). Total Mass: 2,500,000 kg (5,500,000 lb). Core Diameter: 17.00 m (55.00 ft). Total Length: 200.00 m (650.00 ft).

• Stage Number: 1. 1 x Stage: N1 1962 - A. Gross Mass: 1,384,000 kg (3,051,000 lb). Empty Mass: 117,000 kg (257,000 lb). Thrust (vac): 39,420.000 kN (8,861,960 lbf). Isp: 331 sec. Burn time: 103 sec. Isp(sl): 296 sec. Diameter: 10.00 m (32.00 ft). Span: 17.00 m (55.00 ft). Length: 30.00 m (98.00 ft). Propellants: Lox/Kerosene. No Engines: 24. Engine: NK-15. Status: Study 1963. Includes 14,000 kg for Stage 1-2 interstage and payload fairing. Compared to total fuelled mass excludes 15,000 kg propellant expended in thrust build-up and boil-off prior to liftoff. Values as in draft project as defended on 2-16 July 1962.

• Stage Number: 2. 1 x Stage: N1 Nuclear AF. Gross Mass: 800,000 kg (1,760,000 lb). Empty Mass: 150,000 kg (330,000 lb). Thrust (vac): 7,840.000 kN (1,762,500 lbf). Isp: 810 sec. Burn time: 650 sec. Diameter: 13.00 m (42.00 ft). Span: 13.00 m (42.00 ft). Length: 110.00 m (360.00 ft). Propellants: Nuclear/LH2. No Engines: 40. Engine: YaRD Type AF. Status: Study 1963. N1 nuclear upper stage study, 1963. Figures calculated based on given total stage thrust, specific impulse, engine mass.

• Nuclear N1 designs Nation: USSR. At the end of 1961 the Glushko and Bondaryuk bureaux completed their draft projects on nuclear thermal engines for space vehicle upper stages. It was decided to continue work on development of an engine in the 30 to 40 tonne thrust range. In the following year Korolev was asked to study application of such engines, followed by a specific demand in May 1963 from the Scientific-Technical Soviet for specific recommendations. For a Mars expedition, it was calculated that the AF engine would deliver 40% more payload than a chemical stage, and the V would deliver 50% more. But Korolev’s study also effectively killed the program by noting that his favoured solution, a nuclear electric ion engine, would deliver 70% more payload than the Lox/LH2 stage. Further investigation of nuclear thermal stages for the N1 does not seem to be pursued. Bondaryuk and Glushko turned to Chelomei and his competing UR-700 rocket for future application of such stages.

• Vetrov, G S, S. P. Korolev i evo delo, Nauka, Moscow, 1998. ISBN: 5020036846. The collected papers of Soviet Chief Designer Korolev. A tremendous source of new information and insight on the Soviet space program. Russian language. More at amazon.com...