RD-861K

Yuzhnoye N2O4/UDMH rocket engine. Tsyklon 2 and 3 stage 3; Ikar. Developed 2005. High pressure fuel was used to gimbal the engine in two planes, replacing four thrust vector engines on the basic RD-861.

An improved version of the RD-861 engine first described in a 2005 brochure. High pressure fuel was used to gimbal the engine in two planes, replacing the four thrust vector engines of earlier models. Mass of the engine increased, but specific impulse was increased by 15.6 s; the number of restarts in flight was increased to three; and the burn time was tripled. The mixture ratio was controlled with an accuracy of ±1.0%.

Engine: 194 kg (427 lb). Oxidizer to Fuel Ratio: 2.41. Restarts: 3.