The RD861K engine generates thrust and provides pitch and yaw control of the Cyclone-4 third stage powered flight. The engine is based on a highly reliable RD861 serial engine used in the Cyclone-3's third stage.

The open-cycle RD861K is a single-chamber engine with a turbo-pump-feed system using hypergolic propellants. The engine gimbaling in two mutually perpendicular planes provides thrust vector control.

The RD861K is capable of multiple (up to 5) burns in flight. The turbopump assembly turbine uses oxygen-rich gas as a working fluid.

Ground development tests of the engine are nearing completion.

Basic Specifications

Engine mass, kg

207

Propellants:

Oxidizer                                                                          

Fuel                                                   

 

Nitrogen Tetroxide

Unsymmetrical Dimethylhydrazine

Vacuum thrust, kgf

7916

Vacuum specific impulse, kgf·s/kg

330

Propellant mixture ratio

2,41

Gimbal angle, ang. deg

±5

Running time in flight, s

Up to 480