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    Paper ID



    • Christophe Rothmund


    Société Européenne de Propulsion (SEP)






    SEP's Large Liquid Rocket Engine Division located in Vernon celebrates in 1996 its 25th anniversary, and can also look on 50 years of experience. Created as the LRBA in may 1946, this establishment had the task of developing the first French large liquid propellant rocket : project 4212. This project was cancelled in 1949, but the experience gathered during these initial years proved to be invaluable for subsequent developments. The first "flying" rocket designed in Vernon was the Véronique series of sounding rockets. Of a very simple design, powered by a pressure-fed engine and burning nitric acid and turpentine, this little vehicle formed the basis of larger developments. The same principles of simplicity and efficiency were later applied to Vesta, a much more powerful sounding rocket as well as to the first stage of the first French national launch vehicle Diamant A. Switching to nitrogen peroxyde and UDMH for increased performances, a new stage for Diamant B was designed, as well as Coralie, the second stage of Europe's first launch vehicle Europa. Ranging from 4 up to 35 tons, the pressure-fed engines proved their reliability and efficiency in over 100 sounding rocket launches and over 15 launch vehicle starts. However, the limits of the pressure-feed system were reached with Diamant B and the use of a turbopump became mandatory for larger engines. Such an engine was designed after 1965, using a very simple turbopump, powered by gases coming from a gas generator burning the same propellants than the chamber. This experimental engine became the initial step of a much larger family : that of the Viking engines that powered the first two stages of all Ariane 1 to 4 launch vehicles. Over 700 such engines have been built so far... Beginning in 1973, a new family grew up in Vernon : cryogenic engines. Drawing upon the experience gained by SEPR between 1960 and 1969 on the HM4 engine development, a team combining both former SEPR and LRBA engineers (SEPR and SNECMA Space Division merged in 1969 to form SEP. SEP took over in 1971 the space and propulsion activities of LRBA) designed the turbopump- fed HM7 engine that powers Ariane's third stage. And today, the experience gained on all previous engines was applied o the successful development of Vulcain, Europe's most powerful rocket engine, whose maiden flight on Ariane 5 will have occured in late spring 1996. These two propellant families (storable and cryogenic) as well as the two feed systems (tank pressurization and turbopump) enabled SEP's Vernon facility to master rocket propulsion and to become Europe's leader in liquid rocket engine development.