The Soyuz launcher

The Soyuz 2 launcher, a new version of the 'Soyuz' launcher is nearing the end of the development phase. It offers 2 versions of an improved 3-stage Soyuz 2—1 ('2-1 A' and '2-1 B'), the FREGAT stage and a new fairing made of composite, 4.11 m in diameter and 11.4 m long.

Adaptation of the launcher for the CSG (Soyuz STK)

With its proven reliability in flight, the Soyuz launcher will be used from the CSG with as few changes as possible. The approach chosen for the development programme is rather to adapt the new launch base to the launch vehicle.

This launcher, derived from SOYUZ 2, should nevertheless be adapted slightly to enable it to be launched from the CSG. This new version, called Soyuz STK (STKA for the 3-stage 2-1 A version) will include in particular :

• the parameters for the new trajectories from French Guiana (location of the launch pad and changes to the flight software,
• resistance to the natural environment of French Guiana,
• a telemetry system which is compatible with the frequencies used and the network of CSG stations,
• a system for neutralising the launcher to comply with CSG range safety regulations and changes to the flight software of the 3-stage version and the FREGAT state.

For launches from the CSG, a new function will be added to the automatic anomaly processing system of the SOYUZ launcher (the 'AVD function'), namely the ability to stop the propulsion from the ground if the launcher is considered to be dangerous.

General description

The Soyuz family of launchers has been remarkably reliable and efficient since the beginning of Space exploration.
The spacecraft in this family, which launched the first satellite as well as the first man into Space, have been credited with more than 1,700 launches to date (August 05). Nowadays, the Soyuz launcher is used for manned flights or other flights to the International Space Station (ISS) and for commercial flights managed by the Starsem company.

Soyuz, which was inspired by the two-stage R-7A ballistic missile, made its debut with the launch of Sputnik in 1957.
But, whereas Sputnik was limited to 1.5 tonnes placed on a Low Earth Orbit (LEO), the need to inject heavier payloads required the addition of a third stage (E block), which thus led to creation of the Vostok launcher.
Following progress made in the 1960s, the E block was replaced by the I block, which was much more powerful. This led to the improved Voskhod configuration at first and then to Soyuz.
Finally, the addition of a re-ignitable Ikar upper stage enabled Starsem to launch 24 satellites for the Globalstar constellation with only 6 launches.
Following this achievement, Starsem wheeled out the re-ignitable Fregat upper stage which has opened the way for a complete range of missions (LEO, SSO, MEO, GTO, GEO).

For the Soyuz ST version, the launcher measures 46.1m for 305 tonnes and can place payloads of 4,900kg in low orbit. The payload may even be as heavy as 5,500kg for the Soyuz Fregat launcher.

The current Soyuz launcher consists of four stages: the thrusters (1st stage), the main body (2nd stage), the 3rd stage and the re-ignitable Fregat upper stage (4th stage).

There are 4 thrusters (Blocks B, V, G and D), which are assembled around the main body. The oxidiser tank is in the conical part whereas the kerosene tank is in the cylindrical part.

The thrusters have an RD-107A engine which uses liquid oxygen and kerosene. Each engine has 4 combustion chambers to which are added two other chambers for fuelling the so-called reaction control engines for changing the launcher’s direction.

After lift-off the thrusters burn for 120 seconds and are then jettisoned, the thrust is transferred to the main body by a swivel joint located above the structure in a form of a thruster cone.

The main body is similar in construction to the thrusters with a hammer-head fish shape to adapt it to the 1st stage ($$ forme Soyouz).
This stage has an RD-108A engine, which also has 4 combustion chambers and 4 nozzles. Nominally, the combustion time for the main stage is 290 seconds.

The main body ignites 20 seconds before lift-off in order to check the various engine parameters.

The 3rd stage ignites about 2 seconds before the engine of the main stage is extinguished. The thrust of the stage directly triggers its separation from the main stage.

Between the fuel tank and the oxidiser tank an intermediary compartment houses the avionic systems.

Nominally, the 3rd stage burns for 230 seconds. Once the engine has been cut-off and after separation from the main Fregat stage, the stage performs an avoidance manoeuvre by opening a valve in the liquid oxygen tank.

The upper Fregat stage, qualified in 2000, is an autonomous stage designed to operate as an orbiting spacecraft. It extends the potential of the lower stages of the Soyuz launcher to enable it to cover a full range of orbits.

Fregat consists of 6 spherical tanks (4 for the thruster, 2 for avionics) arranged in a circle. It is independent of the 3 other stages, and has its own navigation and control system as well as its own telemetry systems.

It can be re-ignited up to 20 times during flight, which means it is capable of carrying out complex missions.