Fregat

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

Specifications

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 I_sp, using pure hydrazine, with mass up to 42 kg.

Capabilities

The stage can be restarted multiple times, which has been used to place payloads such as the GIOVE-B satellite into their planned orbits.^[1]

Uses

NPO Lavochkina created many interplanetary probes in the past, 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. Various versions were used by the Soviets as the landing stage for Lunar missions (e.g., Luna-16), as an escape stage to launch modern space probes into interplanetary trajectories (e.g., Venus Express and Mars Express) and as the braking stage to place Phobos-2 into orbit around Mars.

Fregat stages are currently used as the third stage of some Soyuz-FG launch vehicles.

References

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External links

• Fregat page on the manufacturer site

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