Fregat

Fregat
	Model of Fregat at MAKS Airshow, 2013
Manufacturer	NPO Lavochkin
Country of origin	Russia
Used on	Current: Soyuz-2; Retired: Soyuz-FG, Soyuz-ST, Soyuz-U, Zenit-3F
Launch history
Status	Active
Total launches	114
Successes; (stage only)	111
Failed	2
Other	1 (partial failure)
First flight	2 February 2000
General characteristics
Height	Fregat: 1.875 m (6 ft 1.8 in); Fregat-MT: 1.945 m (6 ft 4.6 in); Fregat-SB: 2.435 m (7 ft 11.9 in);
Diameter	Fregat: 3.44 m (11 ft 3 in); Fregat-MT: 3.8 m (12 ft 6 in); Fregat-SB: 3.875 m (12 ft 8.6 in);
Empty mass	Fregat: 945 kg (2,083 lb); Fregat-MT: 1,035 kg (2,282 lb); Fregat-SB: 1,080 kg (2,380 lb);
Gross mass	Fregat: 6,235 kg (13,746 lb); Fregat-MT: 7,640 kg (16,840 lb); Fregat-SB: 11,680 kg (25,750 lb);
Propellant mass	Fregat: 5,307 kg (11,700 lb); Fregat-MT: 6,650 kg (14,660 lb); Fregat-SB: 10,330 kg (22,770 lb);
Powered by	1 × S5.92
Maximum thrust	High: 19.85 kN (4,460 lbf); Low: 13.93 kN (3,130 lbf)
Specific impulse	High: 333.2 s (3.268 km/s); Low: 320 s (3.1 km/s)
Burn time	Up to 1,350 seconds (up to 7 starts)
Propellant	N2O4 / UDMH

Fregat (Russian: Фрегат, lit. 'frigate') is an upper stage developed by NPO Lavochkin for universal compatibility with a wide range of medium- and heavy-lift launch vehicles. Fregat has been used primarily with Soyuz and on a few occasions with Zenit rockets, and entered operational service in February 2000.

Fregat uses a liquid-propellant engine burning unsymmetrical dimethylhydrazine (UDMH) fuel and dinitrogen tetroxide (N₂O₄) oxidizer, a pair of hypergolic propellants that ignite on contact. With a success rate of 97.3%, including two failures and one partial failure, Fregat is among the most reliable upper stages in operation. It has deployed more than 300 payloads into a variety of orbits and is capable of placing three or more spacecraft into distinct orbits during a single mission, owing to its ability to restart up to seven times and operate for a total burn duration of up to 1,350 seconds.