MOSCOW. April 17 (Interfax-AVN) - The TsIAm Aircraft- building Research Institute is completing bench tests of the hyper-sonic jet engine now displayed at the Dvigateli-2002 International exhibition held at the all-Russian Exhibition Center in Moscow, deputy head of the spacecraft motor department of the institute Vyacheslav Semenov told Interfax-Military News Agency on Wednesday. Semenov said that the hyper-sonic jet engine was the most efficient motor provided the spacecraft was traveling within the speed bracket from 1,700 to 4,200 meters per second, that is from 6 to 14 Mach. The motor is to be used as the basis of power plants to be mounted on future aerospace systems and hypersonic trans-continental aircraft. Semenov said that experts of the TsIAm institute had been engaged in development of hyper-sonic engines for more than 30 years; extensive research of processes in combustion chambers, air-intakes and nozzles of the engine was carried out during these years. Unprecedented tests of a round hyper-sonic engine running on liquid hydrogenous fuel were staged at the institute; the engine developed more than six Mach speeds. Yet only a rectangular engine can be used in practice. Such an engine is now being displayed at the Dvigateli-2002 exhibition. Now the TsIAM Institute in cooperation with the Russian Aviation and Space Agency is engaged in preparations for testing a three module hyper-sonic engine developed at the institute. The trials are to be conducted on a flying laboratory that is now being constructed at the institute. The aircraft will have a fuselage eight meters long, the wing-span mounting up to 3.5 meters. It will be carried into space with a rocket carrier and then accelerated to hyper-sonic speed by boosting vehicles. Similar projects are being developed in the United States, Japan and France. Semenov said that the Russian engine excelled its foreign counterparts in dimensions by some 1.5 times.