RD-860

Yuzhnoye N2O4/UDMH rocket engine. Upper stages. Developed 1972. Engine used a novel scheme combining an existing proven combustion chamber but using a pneumatic pump for propellant supply.

This allowed:

• Multiple restarts (up to 15)
• Precision throttling of thrust to any value between 200 and 600 kgf simply by controlling the pneumatic pump, without the need for an elaborate control system with various pressure and flow sensors
• Reduction in the gas needed for propellant feed was reduced by 1.4 to 1.7 times compared to conventional methods
• High accuracy of mixture ratio maintenance
• Stage tanks operated under low pressure
• Thrust increase of existing thrust chambers by 1.4 to 1.8 x
• Use of proven components from mass-produced engines such as combustion chamber, pneumatic pump elements, and control units

Throttled thrust(vac): 1.960 kN (441 lbf). Engine: 30 kg (66 lb). Oxidizer to Fuel Ratio: 2. Restarts: 15.