RD-856

The RD-855 (GRAU Index 8D69M), also known as the RD-69M, is a four nozzle liquid 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]

RD-856 (РД-856)
Country of originSoviet Union
First flightDecember 16, 1965
Last flightJanuary 30, 2009
DesignerYuzhnoye Design Bureau
ManufacturerYuzhmash
ApplicationVernier
Associated L/VR-36, Tsyklon-2 and Tsyklon-3
StatusOut of production
Liquid-fuel engine
PropellantN
2O
4 / UDMH
Mixture ratio1.98
CycleGas Generator
Configuration
Chamber4
Performance
Thrust (vac.)54.23 kN (12,190 lbf)
Chamber pressure7.160 MPa (1,038.5 psi)
Isp (vac.)280.5 s (2.751 km/s)
Burn timeup to 163s
Restarts1
Gimbal range+/- 30°
Dimensions
Length0.9 m (2 ft 11 in)
Diameter3.35 m (11.0 ft)
Dry weight112.5 kg (248 lb)
Used in
R-36, Tsyklon-2 and Tsyklon-3 second stage vernier
References
References[1][2][3]

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

References
  1. "RD-856". Encyclopedia Astronautica. Retrieved 2016-07-06.
  2. Pillet, Nicolas. "Tsiklone - Le deuxième étage" [Tsyklon - The second stage] (in French). Kosmonavtika.com. Retrieved 2016-07-06.
  3. "RD-856". Yuzhnoye. Retrieved 2016-07-06.
  4. Krebs, Gunter Dirk (2016-04-24). "Tsiklon". Gunter's Space Page. Retrieved 2016-07-05.


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