The Kharkiv KhAI-4 was an experimental

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

tailless aircraft In aeronautics, a tailless aircraft is an aircraft with no other horizontal aerodynamic surface besides its main wing. It may still have a fuselage, vertical tail fin (vertical stabilizer), and/or vertical rudder. Theoretical advantages of the ...

tested in 1934. It only made three flights before being grounded as dangerous.

Design and development

The 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. 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. Its low-mounted wing was tetragonal in plan, with sweep (15°) only on the

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

s. Wing tip

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

s, which had a blunted triangular profile, carried slightly more rounded

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adve ...

s. Ailerons occupied the outer 65% of each wing, with the rest filled with an

elevon Elevons or tailerons are aircraft control surfaces that combine the functions of the elevator (used for pitch control) and the aileron (used for roll control), hence the name. They are frequently used on tailless aircraft such as flying wings. A ...

. 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. Its fuselage was short but deep, with an enclosed cabin over the leading edge holding two seats in tandem. A

Shvetsov M-11 The Shvetsov M-11 is a five-cylinder air-cooled radial aircraft engine produced in the Soviet Union between 1923 and 1952.Gunston 1989, p.158. Design and development The Shvetsov M-11 was designed under a 1923 competition in the Soviet Union f ...

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...

, 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. 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.

Operational history

The first flight was piloted by B.N. Kudrin, who found insufficient elevon authority to lift the nose for take-off until he reached , 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.

Specifications

References

{{KhAI aircraft Tailless aircraft Kharkiv Aviation Institute aircraft Aircraft first flown in 1934 1930s Soviet experimental aircraft Kharkiv Aviation Factory aircraft