Multipurpose Fregat

Разгонные блоки «Фрегат»
Multipurpose Fregat upper stage was created at Lavochkin Association, JSC and designed to be used on medium and heavy-lift launch vehicles to inject spacecraft into various target orbits.

Base Fregat upper stage marked the start of the whole family of highly effective upper stages, which were produced and are produced on its base. Application on the Fregat upper stage of additional fuel tanks and jettisonable tanks unit (Fregat-MT and Fregat-SB) made it possible to significantly increase the mass of loaded fuel and thereby increase the efficiency of the upper stage.

The basis of the structural-layout scheme of the Fregat upper stage is a block of tanks built according to a monoblock carrier scheme. It has a torospheric configuration, consisting of six spherical containers welded together, separated by spherical bottoms. Four of them are oxidizer and fuel tanks, two tanks are compartments for on-board instruments and equipment (one of them is sealed).

One of the containers (sealed) contains a monoblock of the control system including satellite navigation equipment and ventilators of thermal control system, another one (not sealed) contains a small instrument compartment, service units, as well as high pressure spherical tanks of sustainer propulsion system and propulsion system of attitude control system (ACS).


Today more than 100 launches of Fregat upper stages of different modifications are performed
Starting from 2000 about 800 Russian and foreign spacecraft were injected into various near-earth orbits and escape orbits.


Fregat-MT upper stage (with medium additional tanks) represents a modified Fregat upper stage and is used for SC launches from Kourou cosmodrome (French Guiana). Modernization consists in adaptation of upper stage radiotelemetry system for operation with European network of ground tracking stations.


The first launch of Fregat upper stage as part of Soyuz LV took part on 9 th February 2000. Payload was composed of payload simulator and Demonstrator device, designed to carry out experiment on the descent to the ground of inflatable structure.

    • autonomous, i.e. provides the whole process of payload injection without interference front he ground;
    • Fregat operation logic envisages a way out from possible non-nominal situations;
    • upper stage provides almost the absolute accuracy of spacecraft injection into target orbits;
    • for the first time in Russia satellite navigation equipment, operating from GLONASS and GPS navigation systems was used in the control loop, thereby significantly increasing the accuracy of spacecraft injection into target orbits;
    • possibility of multiple switching on of sustainer propulsion system with the aim of ensuring of optimal injection;
    • Fregat upper stage is fueled with fuel components before installation on the launch site which makes it universal with respect to any launch vehicles;
    • long active life time длительное время (up to 2 days);
    • possibility to ensure launches from 4 cosmodromes: Baikonur, Vostochny, Plesetsk and Kourou Guiana Space Center (French Guiana).

    • propulsion system consisting of: sustainer propulsion system, stabilization, orientation and launch ensuring propulsion system;
    • control system;
    • telemetry system;
    • transmitting device;
    • antenna feeder systems;
    • chemical current sources;
    • thermal control system (TCS);
    • temperature and pressure control system;
    • radio-range-finder;
    • service units.

Main characteristics

Фрегат Fregat
Фрегат МТ (2).png Fregat-MT
СБ.png Fregat-SB
Initial mass with maximum fueling, kg 6235 7640 11680
Final mass, kg 945 1035 1080
Dimensions: height/diame ter, mm 1875/3440 1945/3800 2435/3875
Fuel components: oxidizer/fuel nitrogen tetroxide / unsymmetrical dimethylhydrazine nitrogen tetroxide / unsymmetrical dimethylhydrazine nitrogen tetroxide / unsymmetrical dimethylhydrazine
Maximum operational fuel reserve/full fueling, kg 5235/5307 6550/6650 10140/10330
Sustainer propulsion system thrust: BT/MT mode, kgf. 2030±100/1420±150 2030±100/1420±150 2030±100/1420±15
Specific impulse: BT/MT mode, f 333,2/320 333,2/320 333,2/320
Maximum switch on number of sustainer engine 7 7 7