Fregat Upper Stage

The Fregat upper stage has a flight-proved propulsion subsystem that is based on a single-chamber Lavochkin engine. Four clusters of three 50-N hydrazine thrusters provide attitude control. The Fregat propulsion system powered the Fobos probe to Mars, and the main engine was fitted on nearly 30 interplanetary spacecraft. During its numerous missions, the engine demonstrated the highest reliability under extreme conditions, exceeding technical specifications. This application of proven, in-production hardware ensures high reliability and lower cost for the Fregat upper stage. Fregat operates on UDMH fuel and N2O4 oxidizer, and has a liftoff mass of up to 6,535 kg. The weight at burnout is 950-1,100 kg.. Vacuum thrust is 19.6 kN., and burn time is up to 877 sec. The engine can be restarted as many as 20 times.
Fregat. Gross Mass: 6,535 kg (14,407 lb). Empty Mass: 1,100 kg (2,400 lb). Thrust (vac): 19.600 kN (4,406 lbf). Isp: 327 sec. Burn time: 877 sec. Diameter: 3.35 m (10.99 ft). Span: 3.35 m (10.99 ft). Length: 1.50 m (4.90 ft). Propellants: N2O4/UDMH. No Engines: 1. Engine: S5.92. Status: Out of Production. Comments: Upper stage developed from propulsion bus for Lavochkin lunar and planetary probes (Luna Ye-8, Mars M1, Fobos 1F).