Encyclopedia Astronautica
UR-500 Stage 3


N2O4/UDMH propellant rocket stage. Loaded/empty mass 23,940/2,180 kg. Thrust 613.11 kN. Vacuum specific impulse 320 seconds. Original Proton third stage design.

Status: Design 1962.
Gross mass: 23,940 kg (52,770 lb).
Unfuelled mass: 2,180 kg (4,800 lb).
Height: 3.70 m (12.10 ft).
Diameter: 4.10 m (13.40 ft).
Span: 4.10 m (13.40 ft).
Thrust: 613.11 kN (137,833 lbf).
Specific impulse: 320 s.
Burn time: 110 s.

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Associated Countries
Associated Engines
  • RD-0212 Kosberg N2O4/UDMH rocket engine. 613 kN. Proton stage 3. Engine unit consisting of 1 RD-0213 maine engine and 4 RD-0214 vernier/steering engines. 8D48 essentially similar to 8D411 and 8D412 and has the same combustion chamber. Isp=324s. First flight 1967. 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...
  • 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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