Vulcain

Vulcain is a rocket engine of the ESA, which is used in the first stage of the Ariane 5. There are two main versions of this engine, Vulcain Vulcain 1 and 2, as well as a version of the Vulcain 1, the Vulcain 1B.

Development

Already in 1957, the French Ministry of Defence decided to develop a cold temperature engine for rockets. The first prototype was made ​​in 1964 in operation. Since then, several generations of the engine have been developed. On the ESA Ministerial Conference in The Hague in 1987, the development of a stronger launcher, the Ariane 5 was decided. But also had a new engine, just the Vulcain engine (formerly HM 60), to be built. Even after a relatively short development time by the company Snecma and EADS Astrium (formerly MBB) was ignited the first Vulcain engine in April 1990, which was used on 4 June 1996 for the first time in a launcher. For the Ariane 5 GS is a slightly modified version of the engine with the designation Vulcain 1B was used. An increase in the combustion chamber pressure to 10 bar having supplied 20 kN more thrust.

For the larger Ariane 5 ECA was due to the increased mass of the upper level a more powerful engine you want, and as has already been the end of the nineties, the successor, the Vulcain 2, developed. In the first flight on 11 December 2002 it came to the structural failure of the nozzle due to high thermal load on the tube structure with which the nozzle is cooled to prevent cracking in the exhaust nozzle, coolant loss and burn through the tube structure. In addition, the nozzle is damaged by axial buckling under vacuum conditions. Then, the engine had to be repaired. The success was Vulcain 2 granted only at the second application on 12 February 2005.

Specifications

Through the further development of Vulcain 2 the performance data was increased in almost all areas. Target was 5 to carry more fuel for the same total tank volume of Ariane. Due to the large difference in density of liquid oxygen to liquid hydrogen the intermediate floor which separates the two fuels was shifted in favor of the volume of oxygen. Thus it is possible, 16 carry additional oxygen loss from t 1 t is hydrogen. In order to promote this additional amount of fuel, the output of the oxygen turbo pump is increased and the increased number of injection nozzles. By this measure, the specific impulse would fall slightly. This was compensated for by increasing the combustion chamber pressure and extension of the exhaust nozzle. As a further performance-enhancing measure, the exhaust gases of the gas generator is blown after passing through the turbines into the lower part of the nozzle, which thrust and the specific impulse, and also slightly increased the nozzle additionally cooled. This no longer works Vulcain 2 by the classical bypass mode but after the bypass procedure with Abgaswiedereinblasung.

Planned development

Because of their anticipated increase in payload mass to the performance of the Vulcain engine be increased as part of the development of the Ariane 5. In addition, the production costs of the engine to be lowered in order to remain competitive in the international market. To achieve these objectives, several studies on the part of the manufacturer SNECMA and CNES have been performed. The specific impulse is increased depending on the version up to 3.7%. With the use of such engine on an Ariane 5 payload would (LEO ) by up to 3.4 t increases in a low orbit.