Liquid rocket engine RD-861K

The RD-861K engine is intended for thrust creation and flight control of Cyclone-4 LV third stage. The engine is designed on the basis of the high-reliable serial RD-861 engine used on the Cyclone LV third stage. 

Usage of basic components of the previous engine (RD-861) ensures high energetic performance and reliability.

The one-chamber pump-fed with self-igniting propellants rocket is designed under the scheme without afterburning of generator gas. 

The RD-861K engine has the following characteristics in comparison with its forerunner: 

- the engine's specific impulse is increased in 15.6 s; 

- number of restarts in flight is increased; 

- the burning time is increased by 3 times. 

The RD-861K has next advantages: 

the thrust vector control system is fed by high-pressure fuel; 
the propellants mixture ratio is ensured with accuracy of ±1,0%, on conditions that ordinary operating terms are provided.

Technical characteristics


Vacuum thrust, kgf7916
Vacuum specific propulsive burn, s330
Mass, kg207
Propellant mixture2.412
Number of restarts5
Burn time, s481