RD-856

N₂O₄ / UDMHMixture ratio1.98CycleGas generatorConfigurationChamber4PerformanceThrust, vacuum54.23 kN (12,190 lbf)Chamber pressure7.160 MPa (1,038.5 psi)Specific impulse, vacuum280.5 s (2.751 km/s)Burn timeUp to 163 sRestarts1Gimbal range±30°DimensionsLength0.9 m (2 ft 11 in)Diameter3.35 m (11.0 ft)Dry weight112.5 kg (248 lb)Used inR-36, Tsyklon-2 and Tsyklon-3 second stage vernierReferencesReferences^[1][2][3]

The RD-856 (GRAU Index 8D69M), also known as the RD-69M, is a four-nozzle liquid-fuel rocket vernier engine, burning N₂O₄ and UDMH in a gas generator cycle.^[3] It was used on the R-36, Tsyklon-2 and Tsyklon-3 second stage as thrust vector control by gimbaling of its nozzle.^[3] The engine is distributed through a cylindrical structure that is integrated around the main engine RD-252 module. The structure includes aerodynamic protection for the nozzles.^[2] The engine was started by a pyrotechnic ignitor.^[2]

The engine was serially produced between 1965 and 1992. It was first launched on December 16, 1965 on an R-36 and its last launch was on January 30, 2009 with the last launch of the Tsyklon-3. The production capability was restarted for the Tsyklon-4 but with the apparent cancellation of the program the engine would still be out of production.^[4]

See also

• R-36 - The Soviet ICBM for which the RD-856 was created.
• Tsyklon-2 - A Soviet small rocket that uses the RD-856.
• Tsyklon-3 - A Soviet small rocket that uses the RD-856.
• Tsyklon-4 - A Ukrainian small rocket project that would have used the RD-856.
• Yuzhnoe Design Bureau - The RD-856 designer bureau.

References

External links

• Yuzhnoye Design Bureau English-language home page Archived 2021-06-29 at the Wayback Machine
• Yuzhmash Home Page