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. It was used on the R-36, Tsyklon-2 and Tsyklon-3 second stage as thrust vector control by gimbaling of its nozzle. 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. The engine was started by a pyrotechnic ignitor. 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.
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This article is an automated import of the Wikipedia article "RD-856", available at https://en.wikipedia.org/wiki/RD-856 . Text is licensed under CC BY-SA 4.0.