As an auxiliary booster rocket is referred to in the aerospace and military rocket that is used at the start and then discarded. They may be attached to the launch vehicle or the outer tank ( as the Space Shuttle ). Boosters are used to generate additional thrust during takeoff.
Are they burned out at popular launchers in 40-60 km altitude, they are separated and end up on the ground or in the water. Some larger boosters like the space shuttle, Ariane 5 and the Energia rocket land softly with the help of parachutes to be re-used or inspected for errors.
Also in the field of aircraft and other atmospheric missile booster to find short-term thrust augmentation application. Missiles with ramjet need for example to achieve the necessary minimum for the engine speed to another power source. Also called jumpstart aircraft come small rocket booster for use. Drones like the CL -289 be started from the supernatant by means of a rocket booster, but larger military aircraft can often be equipped with boosters in order to shorten the take-off distance by means of a JATO launches.
After the fuel used, a distinction is made between two types:
- Solid propellant boosters ( engl. solid rocket booster, SRBs ) as they find the Space Shuttle (as space shuttle solid rocket boosters ) and many types of rockets such as the Delta II, Atlas V and Ariane 5 use. In Soviet and Russian space solid rocket boosters are not used.
- Liquid-propellant boosters ( engl. liquid rocket booster, short LRB ) are used primarily in Soviet / Russian launchers, such as Soyuz or Energia, but also Indian ( GSLV ) and Chinese (LM- 2E and LM -3B ) missiles. On the U.S. side so far only uses the Delta IV Heavy LRBS, continue to the in-progress Falcon Heavy and Atlas V Heavy LRBS use. As a Liquid Fly - Back Booster ( LFBB ) are called reusable liquid propellant boosters that should lower their return by plane to the starting point as the high start-up costs.
- Some launchers even a mix of SRB and LRB is used, eg in the European Ariane 44LP. The Japanese H -2A, the mix was planned, but was not implemented.
Boosters are often two or four, depending on the payload to be achieved, are used to guarantee symmetrical thrust conditions; but they are also accessible in the combination of three, six or nine boosters. In the Energia booster were bundled in pairs and you could see the rocket with two ( realized), use three or four such pairs booster. Of Delta II 3, 4 or 9 booster may be used. Some rockets such as the Atlas V booster can use in unbalanced conditions; in this case, the thrust vector of the booster must pass through the center of mass of the rocket.
Wind tunnel model of a reusable booster ( Ariane 5 Liquid Fly - Back Booster )
A Delta IV Heavy with two liquid-propellant boosters
The upper part of a " GEM 46" solid booster of a Delta II Heavy compared to the size of a technician