Engine Model: RD-809. Manufacturer Name: RD-809. Designer: Yuzhnoye. Application: Upper stages. Propellants: Lox/Kerosene. Thrust(vac): 88.000 kN (19,783 lbf). Isp: 345 sec. Burn time: 4,000 sec. Length: 1.67 m (5.47 ft). Chambers: 4. Chamber Pressure: 87.75 bar. Oxidizer to Fuel Ratio: 2.50. Country: Ukraine. Status: Design concept 2007. The RD-809 engine was a design concept for a four-chamber restartable main engine for launch vehicle upper stages. The engine was evidentaly a restartable version of the RD-8 Zenit-2 second stage vernier engine assembly and had the following features:
- Long service life (4000 seconds, five restarts)
- Designed for installation in the upper stage after a factory firing test without the need for post -test refurbishment
- Stage flight control is effected by gimballing each combustion chamber ±10% in one plane.
- All four-chambers pump-fed using a combustion scheme with oxidizer-rich gas feeding the turbopumpts.
- Turbine rotor spun-up by a pneumatic starter
- Propellants in the combustion chamber and gas generator ignited by dedicated startup fuel
- Pneumatic gimabl units used helium gas delivered via electric-pneumatic valves
- Single-mode engine providing constant thrust and propellant mixture ratio within ±4.5% / ±8.
- Pressure sensors provide data for automatic startup and shutdown of engine
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