The Kharkiv KhAI-3 or Aviavnito-3 was one of several

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

mid-1930s

motor glider A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flig ...

transports intended to reduce transport costs.

Design and development

Alexandr Alekseyevich Lazerev, who led the Kharkiv KhAI-3 Avianvito design team, was already familiar with the problems posed by

tailless aircraft In aeronautics, a tailless aircraft is a fixed-wing 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 advanta ...

. He was on the team which designed the almost uncontrollable KhAI-4 two years before (the Institute's designs did not always appear in their numerical order). That aircraft was grounded after just three flights for being dangerous. The much larger KhAI-3 was intended to show that low-powered aircraft could carry a useful eleven-passenger load with an engine of just over . It was a tailless aircraft with a broad- chord wing and with a tractor engine,

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. F ...

and

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

all on the centreline. Though there were initial thoughts of mounting the KhAI-3's

Shvetsov M-11 The Shvetsov M-11 is a five-cylinder air-cooled radial engine, 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 S ...

five cylinder

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

on a pylon over the wing, it was finally placed ahead of the leading edge on steel tubes running from the front

wing spar In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles (or thereabouts depending on wing sweep) to the fuselage. The spar carries flight loads and the weight of the wings while on ...

and fed from four tanks in the wing. There were two long, six seat cabins on each side of the centerline, with the pilot in the first portside seat. The large, triangular

mounted a broad, round-topped rudder. Its wing center section was rectangular in plan, with a steel tube four spar structure and

dural Dural is a semi rural suburb of Sydney, in the state of New South Wales, Australia 36 kilometres north-west of the Sydney central business district in the local government areas of Hornsby Shire and The Hills Shire. Dural is part of the Hills ...

skinning. It had a chord of and a chord/thickness ratio of 14%. The outer panels making up 82% of the span, were all-wood with dihedral and 16° of sweep on the

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

only. The panels decreased in thickness outwards from 14% to 7%, with 8° washout. Each wing carried three control surfaces. Near each tip, at midchord and parallel to the leading edge there was a rectangular air brake which were operated differentially by pedals which also controlled the rudder to assist in making turns. Inboard of the air brakes, each outer panel

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

carried two broad-chord control surfaces that acted as both

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

and

elevators An elevator (American English) or lift (English in the Commonwealth of Nations, Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive tracti ...

. The Kharkiv KhAI-3 had a fixed,

tailwheel undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft Landing gear, undercarriage consisting of two main wheels forward of the Center of gravity of an aircraft, center of gravity and a small wheel or skid to support the tail ...

. Its forward-mounted engine and propeller allowed a short tailwheel to provide a ground

angle of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a Airfoil#Airfoil terminology, reference line on a body (often the chord (aircraft), chord line of an airfoil) and the vector (geometry), vector representing the relat ...

of 15°, avoiding one of the problems encountered with the KhAI-4.

Operational history

The first flight was made on 14 September 1936. On this occasion the front seats of both cabins were equipped with dual controls; the pilots were V. A. Borodin and E. I. Schwartz. During this and subsequent flights, controlled turns proved difficult however the various control surfaces were combined. A long development programme yielded significant improvements. The 1937 Aviavnito-8 was a proposed but unflown development with the same passenger capacity, dimensions and engine.

Specifications

References

{{KhAI aircraft Flying wings Twin-fuselage aircraft Kharkiv Aviation Institute aircraft Aircraft first flown in 1936 1930s Soviet airliners Single-engined tractor aircraft Aircraft with fixed conventional landing gear