Encyclopedia Astronautica
UR-500 Polyblock Stage 1P

RD-253 engine
Credit: Khrunichev
N2O4/UDMH propellant rocket stage. Loaded/empty mass 378,900/26,900 kg. Thrust 8,989.70 kN. Vacuum specific impulse 310 seconds. Original 'Polyblock' design for Proton first stage. This was selected configuration; although somewhat greater in dry mass, it had the advantages of shorter length.

No Engines: 4.

Status: Design 1962.
Gross mass: 378,900 kg (835,300 lb).
Unfuelled mass: 26,900 kg (59,300 lb).
Height: 21.20 m (69.50 ft).
Diameter: 4.10 m (13.40 ft).
Span: 7.40 m (24.20 ft).
Thrust: 8,989.70 kN (2,020,965 lbf).
Specific impulse: 310 s.
Specific impulse sea level: 280 s.
Burn time: 119 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
  • Polyblock UR-500 Russian orbital launch vehicle. UR-500 design studies considered two variants of the first stage: polyblock and monoblock. The polyblock variant consisted of a centre large diameter oxidizer tank surrounded by several smaller diameter fuel tanks. This version could be assembled in a special rig with the lateral blocks being sequentially mounted on the centre. In January 1962 this design was chosen as most advantageous, following studies that indicated improved wind loads and bending moment characteristics compared to the monoblock design. The developed version of the design would become known as the Proton. 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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