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FREGAT: NEW RUSSIAN SPACE TUG

Stanislav Koulikov,
General Designer,
General Director of Lavochkin Association

Nickolai Leontiev,
General Designer,
General Director of KBHM named after A.M.Isaev

Perspective of significant increasing of injected payload mass onto the near-Earth and transfer orbits by existing launch vehicles of the middle and heavy classes is connected with creation of the universal upper stages. One of such upper stages is high-energetic FREGAT was created by Lavochkin Association under participation of Isaev KBHM as an elaborator of propulsion subsystems.

First qualification launch of a new russian interorbital tug – universal upper stage FREGAT was performed on February 9, 2000 from Baikonour launch site. With its first launch (first two launches are qualificational) realization of one of the most important ESA programs – CLUSTER-2 financed by joint stock company STARSEM, France, begins.

Already during the first flight of FREGAT possibility of multitime ignition of its propulsion subsystem was proved, possibility of the payload returning to the Earth from LEOs with using of a new descent technology, based on applying of inflatable bracking device was demonstrated. Development of the new technology “know how” of Lavochkin Association was done under finance and marketing support of Daimler Chrysler Aerospace (Germany).

FREGAT upper stage is designed for solving of the following tasks:

• Transfer of one or a few spacecrafts from parking orbit onto the working orbit or the flight trajectory;

• Putting of the spacecrafts onto different working orbits in the case of a group launch;

• Upper stage transfer from the open orbit onto the parking closed orbit (operation is called “additional launch”);

• Upper stage stabilization on active and passive parts of the flight;

• Forming and giving of the commands onto separation of the head fairing, separation of the upper stage, separation of the spacecraft;

• Building of the necessary orientation before the spacecraft separation.

• Upper stage removing from the working orbit.

Two propulsion subsystems are in the composition of FREGAT: main propulsion subsystem and propulsion subsystem of stabilization, orientation and ignition providing.

Base of the main propulsion subsystem is C5.92 engine. Its main characteristics are: thrust 2000 kgf, specific pulse 328,5 s, maximal number of ignitions 20, fuel components – nitrogen tetraoxide (oxidizer) and non-symmetrical dimethylhydrazin (fuel), working fuel mass (maximal) is 5350 kg.

Base of propulsion subsystem of stabilization, orientation and ignition providing is one component hydrazine engine with the active catalyst c5.221 with the thrust of 5 kgf. Number of the engines is 12, their specific pulse is 225 s.

Practically full abscence in FREGAT composition of a new developed assemblies and systems will let to provide high reliability of the upper stage from the very beginning of its flight exploitation, and also possibility of creation of a new upper stages on their base.

Successfully performed 20.03.2000 second launch of FREGAT has proved its readiness for CLUSTER-2 program execution.