Overcoming Ariane’s quirks and foibles
Reactivity, rapidity and flexibility
This initiative was set up by Professor Jean Lebrun, who had contacts in SEP (European Propulsion Company, which today is a division of the engine maker SNECMA, which provides Ariane’s engines). With the co-operation of Professor Albert Germain, who runs the Industrial Chemistry Laboratory, and Jean Bozet, who set up the EMT department (Eléments de Machines & Tribologie – Machine and Tribology Elements). In 1985 the European rocket experienced dramatic failures due to the thrust-off sequence of the HM7 cryogenic engine in its third stage: the booster rocket would not ignite properly. The injection of liquid oxygen in the combustion chamber posed severe problems. The behaviour of this oxygen needed to be understood at all cost. Liègois expertise, within the EMT, in cryo-mechanics technology was brought to bear to this task, having been called upon by the SEP, which needed an urgent solution to the problem in the interests of its clients: ESA (European Space Agency), CNES (The French National Space Centre) and the Arianespace company.
The EMT department, the Industrial Chemistry and Thermodynamics Laboratories demonstrated reactivity, rapidity and flexibility in fulfilling its test contracts with the SEP. As well as analyzing the HM7 engine ignition phase, it was asked to see to it that the turbopump, which turns at 14,000 revolutions per minute to supply the engine with liquid oxygen, rotated better and more efficiently. The University of Liège, with the support of the ESA, equipped itself with a cryo-tribology test rig to test the mechanisms destined to fly aboard Ariane. Its team of researchers, along with Jean-Luc Bozet, Patrick Kreit and Claude Dodet, showed that they were up to the demands of the Ariane engine provider in qualifying as fit for purpose the rotations of the third stage oxygen turbopump. The European rocket, in its Ariane 4 version, no longer had any problems, until the arrival of the heavy-lift Ariane 5 launchers.