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Kharkiv KhAI-4
The Kharkiv KhAI-4 was an experimental Soviet tailless aircraft tested in 1934. It only made three flights before being grounded as dangerous. Design and developmentThe KhAI-4 was the Kharkov Institute's first tailless design, making its first flight two years before the Kharkov KhAI-3. It was an all-wood machine.[1] It was rather similar in layout to the powered version of the Lippisch Delta 1, first flown three years earlier in 1931, and had similar dimensions but a much more powerful engine.[2][3] Its low-mounted wing was tetragonal in plan, with sweep (15°) only on the leading edges. Wing tip fins, which had a blunted triangular profile, carried slightly more rounded rudders. Ailerons occupied the outer 65% of each wing, with the rest filled with an elevon. The controls were essentially conventional, with rudder pedals and a wheel for the ailerons which, when pushed or pulled moved the elevons together to change pitch.[1] Its fuselage was short but deep, with an enclosed cabin over the leading edge holding two seats in tandem. A Shvetsov M-11 radial engine, working in pusher configuration, was mounted high on the rear fuselage with its five cylinders exposed for cooling. Under the engine the fuselage was cut away.[1] The KhAI-4 had a conventional fixed undercarriage, though the need for propeller ground clearance required a long tailwheel leg, producing a low ground angle of attack.[1] Operational historyThe first flight was piloted by B.N. Kudrin, who found insufficient elevon authority to lift the nose for take-off until he reached 180 km/h (110 mph; 97 kn), the design maximum airspeed. Pitch instability dominated the rest of the flight, though he landed successfully. Two more flights were made before the KhAI-4 was grounded as dangerous.[1] SpecificationsData from Russian Aircraft 1875-1995[1] General characteristics
Performance
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