| Antonov A-9 | |
|---|---|
| General information | |
| Type | Single seatsailplane |
| Designer | O.K. Antonov |
| Number built | 27[1] |
| History | |
| First flight | 1948 |
TheAntonov A-9 was a single-seatsailplane designed and built in theUSSR in the 1940s, a development of the record settingRed Front 7.
Oleg Antonov had designed sailplanes since the early 1930s, most memorably the Red Front 7 which, flown by Olga Klepikova, set a world distance record of 749 km (465 mi) that stood from 1939 to 1951. The A-9 is seen as a development of that aircraft, though detailed information from this period ofSoviet aviation is often limited. Thefuselages and tail units of the two aircraft were very similar but the wings were quite different.[2]
The A-9 was acantilever,shoulder wing monoplane. In plan, the wing had a short, constantchord centre section and long, straight tapered outer panels, with a sweep on both edges, terminating in rounded and downward-curledwingtips. The panels were demountable from the centre section for transport; unusually, the centre section was an integral part of the fuselage structure, its singlebox spar spanning the 3.2 m (10 ft) section unbroken. The spar continued beyond the central section-outer panel joint, the whole wing havingplywood covering ahead of the spar andaircraft fabric covering aft. Long span, tapered, fabric covered and mass balancedailerons occupied about two-thirds of thetrailing edges of the outer panels; these panels also carriedSchempp-Hirth-typeairbrakes, placed just behind the spar and ending at the panel mounting joint. The wing section was slightly reflexed towards the rear and thick, with maximum depth far forward at only about 20% chord, making the profile steep-nosed.[2]
The ply-covered fuselage of the A-9 was oval in cross-section, deep ahead of the wings and almost circular to the rear, giving it a pod-and-boom appearance. The fixed tail surfaces were also ply-covered, thefin narrow but with a small fuselagefillet. The control surfaces were fabric covered. In plan the horizontal tail was tapered with sweep on both edges; the broad, curved andbalanced rudder reached to the keel and was hinged well aft, almost in line with theelevator trailing edge, for clearance and moment. The upper fuselage line was almost flat, even over the rear part of the long, two piececanopy, though its windscreen curved down sharply into the nose. There was no skid or wheeledundercarriage; instead the A-9 was launched from a wheeled, drop-offdolly and landed on the locally internally strengthened fuselage underside, aided by a tail bumper.[2]
Overall, the structure of the A-9 was heavy and so thewing loading was high at 30.5 kg/m2 (6.2 lb/ft2),[2] compared, for example, with theSlingsby T.25 Gull 4, a contemporary glider with a wing loading of 22.3 kg/m2 (4.6 lb/ft2).[3] Higher wing loadings provide higher speeds and better glide angles between thermals but poor climbing in weak lift.[4] The Red Front 7 is known to have usedwater ballast on its record flight[4] but the A-9 was not thus equipped.[1]
Because of their speed, the A-9s concentrated mostly on competition flying and record setting.[1]
Data from Sailplanes 1945–1965[2]
Data from Sailplanes 1945–1965[2]
General characteristics
Performance
