RD-0255

RD-0255 is a designation for a specific engine developed by Energomash, a Russian rocket engine manufacturer. It is a hypergolic liquid rocket engine burning unsymmetrical dimethylhydrazine (UDMH) as fuel and nitrogen tetroxide (NTO) as oxidizer. The RD-0255 served as the vernier engine on the Soviet Union's R-36 ICBM (NATO reporting name: SS-9 Scarp).

Its primary function was to provide precise course correction and attitude control during the later stages of the missile's flight trajectory. Being a vernier engine, it offered significantly lower thrust compared to the main engines responsible for the initial phases of launch. This allowed for finely tuned adjustments that were critical for accurate targeting.

The use of hypergolic propellants meant that the engine ignited spontaneously upon contact between the fuel and oxidizer, offering high reliability and simplified engine design. This was especially important for ICBM applications where quick and dependable start-up was paramount.

While primarily associated with the R-36 missile, the RD-0255 design may have influenced subsequent developments in Russian rocket engine technology, although direct lineage is difficult to confirm given the secrecy surrounding military applications. Detailed specifications regarding thrust, specific impulse, and operating parameters of the RD-0255 are often kept confidential, but it is generally understood to be a relatively compact and efficient engine for its specific role in the R-36 system.