The Antonov An-8 is a twin-turboprop, high-wing light military transport aircraft.
In December 1951, OKB-153 initiated the design of a twin-engine assault transport aircraft, designated DT-5/8, to be powered by two Kuznetsov TV-2 turboprop engines, and fitted with a large rear cargo door to allow vehicles to be driven straight into the hold.
On 11 December 1953, the Soviet Council of Ministers issued directive No.2922-1251 to the Antonov OKB, requiring them to build a twin-turboprop transport aircraft derived from the DT-5/8.
Bearing the in-house designation Izdeliye P the resulting aircraft followed state-of-the-art practice with a high wing carrying two propeller engines, atop a rectangular section fuselage, tricycle undercarriage with main gear units housed in pods on either side of the fuselage, and an upswept rear fuselage providing clearance of the tail unit for loading and unloading.
Following State acceptance trials, production was not recommended due to poor spin characteristics, directional stability and control issues, nose wheel shimmy, poor controllability when landing in crosswinds above 6 m/s (12 kt) and also bad oscillations in all three axes which were difficult to control and made piloting the prototype tiring.
As well as the aerodynamic faults, the TV-2 engines proved difficult to start with unstable gas dynamics at altitudes above 6,000 m (19,700 ft).
The Antonov OKB set about rectifying these faults with increased-area vertical and horizontal tail surfaces, anti-spin strakes on the upper rear fuselage sides, deleting the wing LE slats, local structural reinforcements and replacing the TV-2 engines with Ivchenko AI-20D turboprop engines, which had the added benefit of reducing the empty weight by three tonnes (6,600 lb).
The new design required the use of new production techniques, such as stamping and forging of large high-strength parts, extrusion of long sections, chemical milling of large skin panels and other new techniques.
Given the service designation An-8, the new transport was built in the GAZ-34 factory in Tashkent from 1957 to 1961, as a larger-capacity replacement for the earlier Lisunov Li-2 (DC-3), with a large unpressurized hold, a manned tail gun position, chin radome for navigation/mapping radar and a glazed nose for the navigator.