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Aviation History
1957
1957 - 0786.PDF
792 FLIGHT, 14 June 1957 Atar Volant TRUTH STRANGER THAN SCIENCE FICTION TWO years ago, in our issue of June 24, 1955, we publishedan exclusive, comprehensive appraisal of the "coleopter"type of aircraft developed by the Bureau Technique Zborowski. To many, this concept of a family of tail-standing,VTO, annular-wing machines must have seemed more akin to science fiction than to serious work worthy of support with sub-stantial outlays of public money. Such is by no means the case, for the French government are now supporting the developmentof the concept with an eventual view to the realization of prac- ticable weapon systems and transport vehicles. Much of the fundamental research work has been assigned toS.N.E.C.M.A., the great French nationalized aero-engine com- pany. They have undertaken extensive tunnel research into severalspecies of coleopter and have now completed the first stage of flight-test development, to the following programme: 1954,tethered flight of a remotely controlled VTO model equipped .vith a S.N.E.C.M.A. Ecrevisse pulsejet of 100 lb thrust; 1955,vertical rig tests of an Atar oil system; gimbal-rig tests on the effectiveness of Atar jet-deflection devices; mobile bench investtigations into ground effect; 1956, first tests on a remotely-con- trolled gimbal mounted Atar Volant (C-400 P-l) with gyroscopiccontrol; start of remotely-controlled tethered trials with the Atar Volant to investigate stabilization and influence of wind; 1957,start of flight trials of the piloted Atar Volant C-400 P-2, including an official test on April 8 and free (i.e., untethered) flying on theairfield at Melun from May 14 onwards. There are actually three types of Atar Volant. The P-l is aremotely-controlled device comprising an Atar DV turbojet rated at 6,393 lb thrust and controlled through electric signal cables.The P-l has completed more than 250 flights under the remote com- mand of two pilots, MM. Servanty and Morel (S.N.E.C.M.A.chief test pilot). The P-2 is generally similar but carries a pilot ejection seat above the air intake and an instrument panel andcontrols. Annular tanks surrounding the compressor of the Atar contain a total of 1,100 lb of fuel, sufficient for more than fourminutes' flight at sea level. Take-off weight is 5,730 lb (90 per cent of the thrust of the Atar at peak r.p.m.). The P-3, which is nowunder construction, will be equipped with a vertical Atar E of some 7,700 lb thrust and will be equipped with a tilting ejectionseat inside an enclosed cockpit. It will not have lifting surfaces and so will be restricted to flight in substantially vertical attitudes,but will serve to hasten development of the optimum cockpit for the definitive coleopter capable of flight both vertically andhorizontally. (Lett) S.N.E.C.M.A. test pilot Auguste Morel seated some 22ft from the ground on the Atar Volant (Flying Atar) C-400 P-2. A Radar. B Atar turbojet intake. C Pressurized cockpit, housing tilting seat. D Accessory section. E Auxiliary tank. F Ramjet annular intake. G Fuel tankage. H Atar turbojet. J Ramjet combustion section. K Atar nozzle with four peripheral air jets for control. L Turbojet efflux. shown deflected. M Control surfaces. N Landing gear. /////777 77 77/77777 7 Simplified cross-section of a coleopter intercepter. Airframes for complete prototype coleopters are at present beingconstructed at Chatillon-sous-Bagneux by S.N.C.A. du Nord. We present here a cross-section of a typical intercepter coleopter withAtar power. As the diagram shows, the annular wing is used to form the outer wall of an integral ramjet surrounding the centrallymounted Atar. Control at low forward speeds is obtained by deflecting the efflux from the Atar by high-velocity jets of com-pressor-bleed air expelled through four slots arranged around the main propelling nozzle. In addition there are four 'compressor-bleed jets mounted tangentially on the ends of radial pipes, to provide directional control about the vertical axis, i.e., the majoraxis of symmetry. Compared with conventional aircraft such a device would bemore compact and would present far less acute structural prob- lems. Moreover, it would have true VTOL ability yet couldreadily be designed to have high supersonic level speed. One of the few disadvantages is that there is not a great deal of internalvolume for the fuel; but it is, nevertheless, possible to visualize point-defence functions for which the endurance of such a machine(perhaps five minutes at full power) would be adequate. In this context it is worth pointing out that dead-stick landings areimpossible. S.N.E.C.M.A. have European rights to military annular-wingapplications. They also have certain other interests in the coleopter, and are reported to be planning a multi-purpose vehicle drivenby ducted fans powered by one or more General Electric T58 shaft turbines.Meanwhile the original B.T.Z. organization has now been re-constituted as a joint-stock company (the Societe Anonyme 'Bureau Technique Zborowski) who have a new building at 1/3 Avenue d'Orleans, Brunoy, S. et O. During the past two years theB.T.Z. has investigated the pilotless intercepter Charancon VI, followed by the improved Charancon VIII with a BristolOrpheus 3, as well as the Hanneton III-A touring aircraft and numerous surface- or air-launched guided missiles. •/,
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