Fregat

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Model of the Fregat-SB, as configured for the Fobos-Grunt mission.

Fregat (Russian: Фрегат, frigate) is a space tug developed by NPO Lavochkin in the 1990s. Its main engine is a liquid propellant rocket that uses UDMH and N2O4 as propellants.

Specifications[edit]

The dry mass of a Fregat (as of October 2006) is 924 kg; with fuel the mass is up to 5350 kg. Current modification of the main engine has a specific impulse of 332 s and a thrust of 2018 kg.[citation needed] The reaction control system includes 12 engines, each having 5 kg thrust, 225 s Isp, using pure hydrazine, with mass up to 42 kg. Height: 1,500 mm, Diameter 3,350 mm, Fueled Mass: 6,415-6,535 kg., Firing Duration: 1350 seconds[1]

Capabilities[edit]

The stage can be restarted multiple times, which has been used to place payloads such as the GIOVE-B satellite into their planned orbits.[2]

Uses[edit]

NPO Lavochkin has built many interplanetary probes, and the Fregat stage follows their design traditions. The main part of the stage is six intersecting spheres placed on a single plane, four of which contain propellants. The remaining two contain the control equipment. The main engine is placed between the spheres, so Fregat is a tightly-packed stage with a diameter much larger than its height.

Fregat is a versatile spacecraft: for example, in addition to orbital insertion, it can be used as an escape stage to launch modern space probes into interplanetary trajectories (e.g. Venus Express and Mars Express).

Fregat-SB[edit]

Fregat stages are currently used as the fourth stage of some Soyuz-FG launch vehicles. A version called Fregat-SB can be used with Zenit-2SB rocket. This version has a block of drop-off tanks ("SBB" or Сбрасываемый Блок Баков in Russian) which makes increased payload capability possible. The torus-shaped SBB weighs 360 kg and contains up to 3050 kg of propellant. The total dry weight of the Fregat-SB (including SBB) is 1410 kg and the maximum propellant carrying capacity is 10150 kg. [3]

Fregat-SB was launched for the first time on 20 January 2011, when it lifted the Elektro-L weather satellite into geosynchronous orbit.[4]

References[edit]

External links[edit]