RD-855

The RD-855 (GRAU Index 8D68M), also known as the RD-68M, is a four nozzle liquid rocket vernier engine, burning N2O4 and UDMH in a gas generator cycle. It was used on the R-36, Tsyklon-2 and Tsyklon-3 first 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-251 module. The structure includes aerodynamic protection for the nozzles and small retro engines to assure the separation of the first stage. The engine was ignited two second before the RD-251 main engine.


The RD-855 (GRAU Index 8D68M), also known as the RD-68M, is a four nozzle liquid rocket vernier engine, burning N2O4 and UDMH in a gas generator cycle. It was used on the R-36, Tsyklon-2 and Tsyklon-3 first 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-251 module. The structure includes aerodynamic protection for the nozzles and small retro engines to assure the separation of the first stage. The engine was ignited two second before the RD-251 main engine.
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