The RD-250 (, GRAU index: 8D518) is the base version of a dual-nozzle family of liquid-fuel rocket engines, burning a hypergolic mixture of unsymmetrical dimethylhydrazine (UDMH) fuel with dinitrogen tetroxide oxidizer in a gas-generator open cycle.[1] The RD-250 was developed by OKB-456 for Yangel's PA Yuzhmash ICBM, the R-36 (8K67). Its variations were also used on the Tsyklon-2 and Tsyklon-3 launch vehicles. It was supposed to be used on the Tsyklon-4, but since the cancellation of the project it should be considered as out of production. Three engines from this family bundled together make the corresponding RD-251 propulsion module.
Versions
The engine has seen different versions made:
- RD-250 (GRAU index: 8D518): Base engine of the family. Used on the R-36. A bundle of three RD-250 form the RD-251 cluster.
- RD-250P (GRAU index: 8D518P): Improved version of the RD-250. Used on the