Encyclopedia Astronautica
UR-100N Stage 2N


N2O4/UDMH propellant rocket stage. Loaded/empty mass 12,195/1,485 kg. Thrust 214.27 kN. Vacuum specific impulse 322 seconds. Engine has one main engine and four verniers. Verniers continue to burn for 19 seconds after mainstage shutoff.

Status: Active.
Gross mass: 12,195 kg (26,885 lb).
Unfuelled mass: 1,485 kg (3,273 lb).
Height: 3.90 m (12.70 ft).
Diameter: 2.50 m (8.20 ft).
Span: 2.50 m (8.20 ft).
Thrust: 214.27 kN (48,170 lbf).
Specific impulse: 322 s.
Burn time: 183 s.
Number: 178 .

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Associated Countries
Associated Engines
  • RD-0235 Kosberg N2O4/UDMH rocket engine. 240 kN. UR-100N / RS-18 (SS-19) stage 2. Main engine based on RD-0217 with larger nozzle for altitude operation. Staged combustion cycle. Isp=320s. First flight 1972. More...
  • RD-0236 Kosberg N2O4/UDMH rocket engine. 15.760 kN. UR-100N / RS-18 (SS-19) stage 2 vernier. Out of Production. Developed in 1969-1974 / problems not solved until 1978. Vernier engines. Gas generator cycle. Isp=293s. More...

Associated Launch Vehicles
  • UR-100N Russian intercontinental ballistic missile. The UR-100N was designed as a replacement for the UR-100 at the end of its ten year storage life. Although it could be installed in the same silos, it was 50% heavier. The competing design of Yangel, the MR-UR-100, was also put into production when the Soviet hierarchy deadlocked and could not pick one design over the other. More...
  • UR-100NU Russian intercontinental ballistic missile. Development of an improved version of the UR-100N was authorised on 16 April 1976 (UR-100NU; U = UTTKh = 'Improved Technical-Tactical Characteristics). Viktor Bugaisk at TsKBM headed the engineering team. The UR-100NU was to have a new warhead dispenser bus and improved guidance system by Vladimir Sergeyev of NII-692. The new system allowed up to six pre-programmed targets to be entered, any one of which could be selected at launch. This allowed deployment of better countermeasures and a considerable improvement in accuracy. More...
  • Rokot Russian all-solid orbital launch vehicle, consisting of decommissioned UR-100N ICBMs with a Briz-KM upper stage. More...
  • Rokot K Russian all-solid orbital launch vehicle. Version with Briz-K upper stage. More...
  • Strela Russian intercontinental ballistic missile. Launch vehicle by NPO MASH based on UR-100N's decommissioned from Ukrainian missile fields. 106 tonne liftoff mass. More...

Associated Propellants
  • N2O4/UDMH Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Unsymmetrical Dimethylhydrazine ((CH3)2NNH2) became the storable liquid fuel of choice by the mid-1950's. Development of UDMH in the Soviet Union began in 1949. It is used in virtually all storable liquid rocket engines except for some orbital manoeuvring engines in the United States, where MMH has been preferred due to a slightly higher density and performance. More...

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