RD-107

The RD -107 ( двигатель of Russian Реактйвный, " Reaktiwny Dwigatel ") is a rocket engine for liquid rocket. It was developed by the Soviet chief engineer for rocket motors Valentin Petrovich Glushko in the period 1954-1957 at the Leningrad gas dynamic laboratory and used in the R-7 variants, such as the Soyuz rocket as a drive for the first stage. First, the Einkammertriebwerke were provided RD -105 and RD -106 for this rocket, but this enlarged versions of the German ED -140 proved to be unstable, after which the work was it set in 1956.

The fact preferred engine RD-107/RD-108 is powered by kerosene and liquid oxygen (LOX ) and has four rigid cylindrical combustion chambers with Paraboldüsen, two pivotable control nozzles and a turbo pump unit with 4000 kW and two main and two auxiliary pumps. The main pumps deliver at full thrust per second 91 kg and 226 kg of oxygen to fuel the combustion chambers, wherein the turbine is running at about 8000 rpm. One of the auxiliary pump promotes hydrogen as a fuel for the turbine of the main pump, the other promotes liquid nitrogen in the fuel tank where it generates in this way a positive pressure.

A derivative of the RD 107 is the RD -108 which is used as a second- stage engine the spacecraft and which has four control nozzles. In contrast to the previous engines RD -100, RD -101 and RD- 103, the thermal load on the combustion chamber wall has been lowered considerably by cooling with fuel. For this, the combustion chambers were designed double in the upper part ( provided with channels ) through which the fuel was pumped. In addition to cooling, the stability of the combustion chamber has been enhanced by this measure, so that the combustion chamber pressure could be increased without damage to more than double.

Caused problems in the development of the engine, especially (as in almost every great rocket engine ) combustion oscillations which can perform periodic changes of pressure and temperature in the combustion chamber to the failure or destruction of the engine. They are formed by incomplete combustion of fuel.

Variants

The first engines for the variants of the R-7 carried the official designation 8D74 and 8D75 ( the RD- X is the name of the manufacturer). They belonged in 1957 to the initial R -7, however, were 971 and 912 kN still too weak to carry the planned payloads ( warheads and the large Sputnik satellites from Sputnik -3). Then very quickly improved / modified variants have been developed. For the RD -107 are 8D74 - 1958 ( for example Luna version ), 8D74 - 1959 ( for example Vostok ) 8D74K (eg for Molniya ), 8D76 (for example, 8A91, so from Sputnik 3), 8D727 and 11D511 (RD -117 for Soyuz ) or for the RD -108 versions 8D75PS ( Sputnik 1 and 2), 8D77 (eg 8A91, ie from Sputnik 3), 8D75 - 1958 ( Luna ), 8D75 - 1959 ( Vostok ) 8D75K (eg Molniya ) 8D727 (eg Molniya ) and 11D512 (RD- 118 Soyuz ).

The engines are still used today in modified form as RD-107A/RD-117 ( 821/1021 kN Boden-/Vakuumschub ) and RD-108A/RD-118 ( 765/1010 kN Boden-/Vakuumschub ) in the different versions of Soyuz employed.

Specifications

Data for the RD -107 and RD- 108.