Encyclopedia Astronautica
N1 Nuclear A


Russian nuclear orbital launch vehicle. A version of the N1 with a nuclear upper stage was studied by Korolev in 1963. It was concluded that the optimum design would allow a single N1 to launch a direct manned lunar landing and return. However for manned Mars missions, a nuclear electric engine was found to be much more efficient. This essentially killed further consideration of thermal nuclear upper stages within the bureau.

Following abandonment of the nuclear-ammonia ICBM projects, the engine bureaus of Bondaryuk (OKB-670) and Glushko (OKB-456) continued study of nuclear propulsion, but using liquid hydrogen for upper stage applications. Engines of 200 metric tons and 40 metric tons thrust with a specific impulse of 900 to 950 seconds were being considered. At the end of 1961 both bureaus completed their draft projects and it was decided to continue work on development of an engine in the 30 to 40 metric ton 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.

Korolev considered three variants based on the N1:

  • A three stage vehicle using the N1 first and second stages and a nuclear third stage
  • A three stage vehicle using the N1 first stage and nuclear second and third stages
  • A two stage vehicle using the N1 first stage and a nuclear second stage
Considered for each case were nuclear engine designs Type A (18 metric tons thrust, 4.8 metric tons mass), AF (20 metric tons thrust, 3.25 metric tons mass), V (40 metric tons thrust, 18 metric tons mass), and V with a bioshield for use on manned flights (40 metric tons thrust, 25 metric tons mass).

The study concluded that the two stage vehicle was the most promising. Compared to an equivalent vehicle using liquid oxygen/liquid hydrogen, mass in low earth orbit would be more than doubled. Optimal stage size was 700 to 800 metric tons for the Type A engines and 1,500 to 2,000 metric tons for the type V engines (this resulted in a halaciously large number of nuclear engines by Western standards). Use of the nuclear stage would result in a single N1 launch being able to launch a round-trip lunar landing (mass landed on lunar surface over 24 metric tons with return of a 5 metric ton capsule to earth).

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 favored 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.

LEO Payload: 270,000 kg (590,000 lb) to a 220 km orbit at 51.60 degrees. Payload: 24,600 kg (54,200 lb) to a lunar surface.

Stage Data - N1 Nuclear A

  • Stage 1. 1 x 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 1962. Comments: 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 2. 1 x N1 Nuclear A. Gross Mass: 700,000 kg (1,540,000 lb). Empty Mass: 250,000 kg (550,000 lb). Thrust (vac): 6,860.000 kN (1,542,180 lbf). Isp: 900 sec. Burn time: 570 sec. Diameter: 12.00 m (39.00 ft). Span: 12.00 m (39.00 ft). Length: 90.00 m (295.00 ft). Propellants: Nuclear/LH2. No Engines: 40. Engine: YaRD Type A. Status: Study 1963. Comments: N1 nuclear upper stage study, 1963. Figures calculated based on given total stage thrust, specific impulse, engine mass.

Status: Study 1963.
Gross mass: 2,400,000 kg (5,200,000 lb).
Payload: 270,000 kg (590,000 lb).
Height: 180.00 m (590.00 ft).
Diameter: 17.00 m (55.00 ft).
Thrust: 35,000.00 kN (7,868,000 lbf).
Apogee: 220 km (130 mi).

More... - Chronology...


Associated Countries
Associated Engines
  • NK-15 Kuznetsov Lox/Kerosene rocket engine. 1544 kN. N-1 stage 1 (block A). Development ended 1964. On the basis of NK-9 the NK-15 was developed for the N-1 launcher. 30 were used on the Block A (Stage 1) of the N-1. Isp=318s. First flight 1969. More...
  • YaRD Type A Korolev nuclear/lh2 rocket engine. 177 kN. Study 1963. Design considered in N1 nuclear upper stage studies. Outgrowth of work done by Bondaryuk and Glushko on YaRD engines for nuclear ICBM's, but using liquid hydrogen as propellant. Isp=900s. More...

See also
  • N1 The N1 launch vehicle, developed by Russia in the 1960's, was to be the Soviet Union's counterpart to the Saturn V. The largest of a family of launch vehicles that were to replace the ICBM-derived launchers then in use, the N series was to launch Soviet cosmonauts to the moon, Mars, and huge space stations into orbit. In comparison to Saturn, the project was started late, starved of funds and priority, and dogged by political and technical struggles between the chief designers Korolev, Glushko, and Chelomei. The end result was four launch failures and cancellation of the project five years after Apollo landed on the moon. Not only did a Soviet cosmonaut never land on the moon, but the Soviet Union even denied that the huge project ever existed. More...

Associated Manufacturers and Agencies
  • Korolev Russian manufacturer of rockets, spacecraft, and rocket engines. Korolev Design Bureau, Kaliningrad, Russia. More...

Associated Stages
  • N1 1962 - A Lox/Kerosene propellant rocket stage. Loaded/empty mass 1,384,000/117,000 kg. Thrust 39,420.00 kN. Vacuum specific impulse 331 seconds. Earlier design for the Block A. 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. More...
  • N1 Nuclear A Nuclear/LH2 propellant rocket stage. Loaded/empty mass 700,000/250,000 kg. Thrust 6,860.00 kN. Vacuum specific impulse 900 seconds. N1 nuclear upper stage study, 1963. Figures calculated based on given total stage thrust, specific impulse, engine mass. More...

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