RD-856

RD-856 (РД-856)

Country of origin	Soviet Union
First flight	December 16, 1965
Last flight	January 30, 2009
Designer	Yuzhnoye Design Bureau
Manufacturer	Yuzhmash
Application	Vernier
Associated LV	R-36, Tsyklon-2 and Tsyklon-3
Status	Out of production
Liquid-fuel engine
Propellant	N2O4 / UDMH
Mixture ratio	1.98
Cycle	Gas generator
Configuration
Chamber	4
Performance
Thrust, vacuum	54.23 kN (12,190 lbf)
Chamber pressure	7.160 MPa (1,038.5 psi)
Specific impulse, vacuum	280.5 s (2.751 km/s)
Burn time	Up to 163 s
Restarts	1
Gimbal range	±30°
Dimensions
Length	0.9 m (2 ft 11 in)
Diameter	3.35 m (11.0 ft)
Dry mass	112.5 kg (248 lb)
Used in
R-36, Tsyklon-2 and Tsyklon-3 second stage vernier
References
References	[1][2][3]

The RD-856 (Russian: Ракетный Двигатель-856, romanized: Raketnyy Dvigatel-856, lit. 'Rocket Engine 856', GRAU index: 8D69M), also known as the RD-69M, is a four-nozzle liquid-fuel rocket vernier engine, burning a hypergolic mixture of unsymmetrical dimethylhydrazine (UDMH) fuel with dinitrogen tetroxide (N₂O₄) oxidizer 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

1. "RD-856". Encyclopedia Astronautica. Archived from the original on June 27, 2002. 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. Archived from the original on 29 May 2015.
4. Krebs, Gunter Dirk (2016-04-24). "Tsiklon". Gunter's Space Page. Retrieved 2016-07-05.

External links

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