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Aviation History
1954
1954 - 1712.PDF
AUSTER A.O.P.9 An Entirely New Rearsby Product, Bombardier-powered, for the British Army IT is a widely known, and often deplored, fact that there is now only one manufacturer of light aircraft in Britain —though fortunately that firm is Auster Aircraft, Ltd., of Rearsby, Leicestershire. It is less well known that every air observation-post aircraft used by the British Army is, and always has been, of Auster manufacture. Thus, the company can fairly claim to know this particular field extremely well. Briefly, the history is that the original Model D was, with slight alterations, produced in numbers for the Army as early as 1940. The principal developments since that date are the Auster III (rear fuselage cut down, cabin transparency increased, power unit Cirrus Major), the Auster IV and V, with the American Lycoming engine (225 of the former and 790 of die latter were built, many of which are still in use in various pans of the world), the post-war A.2/45 (a big, stalky aircraft to a difficult specification, which resulted in a high all-up weight necessitating a Gipsy Queen as power unit), and the A.O.P.6, the standard A.O.P. machine, of which some 500 are now in service, with variations, in many parts of the British Empire as well as in Canada, Jordan (Arab Legion), Greece, Belgium, Indonesia and elsewhere. The A.O.P.6 has the 145 h.p. Gipsy Major 7 with a cartridge starter, and it introduced auxiliary aerofoil flaps, the effective- • ness of which went far towards compensating for the increased all-up weight. Two seats are fitted side by side, together with full radio, and there is also a dual-control trainer variant styled T.7. Some Austers of these marks have been produced with ski or float undercarriages. Although undoubtedly a fine aircraft, and probably the best "buy" in its class in the world, the A.O.P.6 is by no means the ultimate aircraft for Army work. By 1949 the Auster company, die Army and the M.o.S. got together to see what could be expected of future equipment. At this time Black burn and General Aircraft were just getting the Bombardier into a fully developed state, and this exceptionally promising engine, with lively throttle response, appeared a natural choice for use in future A.O.P. machines. As an interim develop ment and demonstration prototype the Auster Model S was produced in 1951, with a Bombardier 702, large low-pressure tyres, and more powerful tail control surfaces; a Bombardier was also installed in a production A.O.P.6. The Model S indicated that the company were thinking along the right lines and that a very useful aircraft could be designed around the Bombardier power plant. Accordingly, during the last two years, the Auster design-staff have been developing an entirely new aircraft styled A.O.P.9, with the company's type number B.5; this machine is so promising and so different from its predecessors that we are according it a full description now that the prototype is flying. It is most important to know that, unlike all other British A.O.P. aircraft, the Mk 9 has not "just growed"; it is a highly coherent design, conceived and developed from scratch on an entirely new basis by an energetic team under the company's chief designer, Mr. R. E. Bird. As the photo graphs show, it looks quite different from its predecessors. It is actually even more different than its appearance might suggest, and undoubtedly is a highly promising basis for future developments in many fields. Indeed, we shall be most surprised if it does not become die patriarch of a large family of exceptionally capable aircraft, able to tackle an immense range of tasks better than can any other machine of comparable size. The essence of the design hinges upon the following fac tors : a fuselage 46in wide (i.e., considerably wider than any previous Auster); an excellent undercarriage, embodying Dowty Liquid Springing and Goodyear disc brakes; a cut- down rear fuselage and extra bulbous canopy, giving superb vision; provision for three seats widi full military radio; a large wing with highly effective flaps and drooping ailerons; and a considerably revised structure, including a wing having a metal torsion-box leading-edge of D section and a single strut, a cantilever stressed-skin tail unit, and seats and floor ing of honeycomb sandwich material, the floor being so arranged that it can readily be taken out and replaced by alternative prefabricated sections fitted with various types of operational gear. A description of the aircraft follows. The wings are significantly larger in area than those used in previous Auster aircraft. The section is constant from root to tip (it is the familiar N.A.C.A. 23012) with 11 deg washout built-in during the assembly of die torsion box. The single spar in each semi-span has a sheet web and T-section booms, and to its forward face are riveted a series of pressed- sheet nose ribs which carry a 2in-diameter light-alloy tube at Uieir forward ends, the tube establishing the position and profile of the leading edge. The torsion box is then com pleted by pop-riveting the pre-formed skin, in two sections on each semi-span, the inner portion being of heavier gauge. The pressed-sheet ribs are cantilevered off the rear face of the spar web. As the large drawing shows, the ribs are cut off by die perforated-sheet flap and aileron shrouds, which are fabric-covered on both sides. Drag loads are taken by a diagonal tubular strut inside the wing. Aft of the spar, the wing is covered with doped fabric, which is attached in the very neat manner shown in the detail sketch on p. 763. The wing tip is a single Durestos moulding, produced in the Auster plastics shop, which is screwed to a flange on the end rib. The forward end of each tip is a large transparent fairing for a powerful light which does duty both as a
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