The RD-0255 is a propulsion module composed of an RD-0256 main engine and a RD-0257 vernier engine. Both are liquid rocket engine, burning UDMH in N₂O₄. The RD-0256 main engine operates in the oxidizer rich staged combustion cycle, while the vernier RD-0257 uses the simpler gas generator cycle. It was used on the R-36MUTTKh (GRAU:15A18) and R-36M2 (GRAU:15A18M). Subsequently, it has been in the Dnepr second stage and as of 2016 it is still in active service.^[4][5]

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The RD-0256 is an improved version of the RD-0228 (GRAU: 15D84), itself composed of an RD-0229 (GRAU: 15D84) main engine and a RD-0230 (GRAU: 15D79) vernier engine.^[6] The RD-0228 was developed between 1967 and 1974 for the first generation of R-36M (GRAU: 15D83) ICBM second stage, but was replaced on subsequent iterations by the RD-0256.^[7] The RD-0228 debut was on January 21, 1973. With the START I and START II the RD-0228 was retired and its successor, the RD-0256, only continued as the Dnepr.^[3][7]

• R-36M – A Soviet ICBM that used the RD-0228 and RD-0255.
• Dnepr – Small launch vehicle designed by Yuzhmash that uses the RD-0255.
• KBKhA – The RD-0228 and RD-0255 design bureau.
• Vernier Engine
• Rocket engine