Encyclopedia Astronautica
UR-100N MIRV Bus


N2O4/UDMH propellant rocket stage. Loaded/empty mass 1,100/725 kg. Thrust 4.90 kN. Vacuum specific impulse 200 seconds.

Status: Active.
Gross mass: 1,100 kg (2,400 lb).
Unfuelled mass: 725 kg (1,598 lb).
Height: 0.50 m (1.64 ft).
Diameter: 2.50 m (8.20 ft).
Span: 2.50 m (8.20 ft).
Thrust: 4.90 kN (1,102 lbf).
Specific impulse: 200 s.
Burn time: 150 s.
Number: 92 .

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Associated Countries
Associated Engines
  • RD-0237 Kosberg N2O4/UDMH rocket engine. 4.9 kN. UR-100N / RS-18 (SS-19) stage 3. MIRV service block. Open cycle. Analogous to RD-0225, pressure fed. Steering engine for space vehicles gimbaling +/- 45 degree. Isp=200s. First flight 1972. More...

Associated Launch Vehicles
  • 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...

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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