RD-170
The RD -170 ( двигатель of Russian Реактивный, " Reaktiwnyj Dwigatel " ) ( GRAU index 11D521 ) is a rocket engine for liquid rocket. It was developed by the Soviet chief engineer for rocket motors Valentin Petrovich Glushko in the period 1976-1986 at the Leningrad gas dynamic laboratory and is now marketed by NPO Energomash. Four RD -170 serve as a booster in the Energia rocket, a modified in the Zenit rocket as a drive for the first stage of the rocket. The RD -170 is still the strongest ever flown thrust liquid rocket engine.
Technology
The RD -170 is powered by kerosene and liquid oxygen (LOX ) and consists of four main combustion chambers that share a turbine with about 190 MW of power and a pump set. The energy required to drive the turbine is provided by a pre-combustion oxygen-rich gas in two generators or precombustion chambers. To the total amount of oxidant and a small amount of fuel is supplied, which burns at low temperature, and the turbine. The exhaust gas then passes from the combustion prechamber to the main combustion chamber where the main part of the fuel is fed and burns. By this design, a so-called main stream engine with a simple pre-combustion ( oxidizer rich staged combustion cycle) is the engine even at the high combustion chamber pressure of 25 MPa no fuel to power the pumps lost, which would otherwise have resulted in significant losses. At the same time the preheating of the cryogenic oxygen improved in the pre-combustion combustion efficiency and reduces the risk of instability in combustion, which may lead to combustion oscillations otherwise. Nevertheless, the engine initially had to contend with problems during tests, as at 25 MPa pressure and 400 ° C inlet temperature in the main combustion chamber, an oxygen- rich atmosphere is difficult to control; the three SSME engines of the Space Shuttle work with 22 MPa with a fuel-rich pre-combustion, the RD -253 operates only at 15 MPa. Another special feature of the engine is that the thrust can be throttled significantly ( to 40 % and 56 % of the nominal value depending on the source ) in order to reduce the burden on the missile structure shortly before the end of firing.
Unlike the Soyuz rocket could be avoided through the engine to additional control thrusters, because the nozzle can be pivoted about an axis in the RD -170 for the Energia. The derived RD -171 ( 11D520 ) for the zenith has a two-axis control ( in use up to 6.3 °, in tests than 8 ° ) of the nozzle for this purpose.
The four boosters of the Energia with the RD -170 engines were reusable laid out and equipped with parachutes. The engines should withstand up to ten starts, where tests showed that they also withstand 20 starts.
As RD -180 (only two combustion chambers, 25.7 MPa chamber pressure and 4,159 kN thrust ), the RD -170 engine used on the Atlas III and Atlas V rocket, as RD -191 (only one combustion chamber, 25.7 MPa chamber pressure, 3230 kg weight and 2,079 kN thrust ) on the Angara rocket. Some sources put the engine from the Zenit- 3SL as RD -173 with an increased to 7,695 kN/8.338 kN thrust, the manufacturer of this called the RD- 171M.