Encyclopedia Astronautica
UR-500 Monoblok Stage 1M


N2O4/UDMH propellant rocket stage. Loaded/empty mass 367,360/25,560 kg. Thrust 8,989.70 kN. Vacuum specific impulse 310 seconds. Original conventional 'Monoblock' design for Proton first stage.

No Engines: 4.

Status: Design 1962.
Gross mass: 367,360 kg (809,890 lb).
Unfuelled mass: 25,560 kg (56,350 lb).
Height: 30.00 m (98.00 ft).
Diameter: 6.20 m (20.30 ft).
Span: 6.20 m (20.30 ft).
Thrust: 8,989.70 kN (2,020,965 lbf).
Specific impulse: 310 s.
Specific impulse sea level: 280 s.
Burn time: 115 s.

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Associated Countries
Associated Engines
  • 11D43 Glushko N2O4/UDMH rocket engine. 1642 kN. Developed 1960-64. Isp=316s. Low-expansion ratio gimbaled variant for Proton stage 1 concept. Configuration 4 x 8D43 clustered with 4 x 11D43 abandoned in favor of 6 x Glushko 11D48 in final Proton design. More...
  • 8D43 + 11D43 Kosberg N2O4/UDMH rocket engine. 2247.450 kN. Design 1962. Isp=310s. Originally the first stage of the Proton was designed for 4 x fixed 11D43 and 4 x gimballed Kosberg 8D43; replaced by 6 x 11D48 from Glushko in final Proton design. More...

Associated Launch Vehicles
  • Monoblock UR-500 Russian orbital launch vehicle. During UR-500 design studies, two variants of the first stage were considered: polyblock and monoblock. The monoblock approach was that the first stage be assembled from two separate modules with the same diameter: an upper oxidiser module and a lower fuel and engine block. In assembly trials of this design it proved difficult, because of the height of the first stage, to obtain access to the upper stages and payload atop the rocket. Although there was a payload advantage compared to the more compact polyblock design, this was relatively small and outweighed by the operational difficulties. 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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