The Antonov An-8 is a Soviet-designed twin-turboprop, high-wing light military transport aircraft.
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 had a high wing carrying two turboprop engines, atop a rectangular-section fuselage which could carry 60 troops or 40 passengers.
Alternatively the aircraft could carry a range of vehicles (including ASU-57 assault guns, BTR-40 or BTR-152 armoured personnel carriers) or artillery pieces.
The aircraft was fitted with a 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.
The aircraft made its first flight on 11 February 1956 from Sviatoshyn Airfield, Kyiv and made its public debut at the Aviation Day air display at Tushino Airfield on 18 August that year.
Following State acceptance trials, production was not recommended due to poor spin characteristics, directional stability and control issues, nosewheel shimmy, poor controllability when landing in crosswinds above 6 m/s (12 kt) and also phugoid 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 were unsuitable, being unstable at high altitudes and difficult to start, as well as having a short service life.
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 leading-edge slats, adding 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 3 tonnes (6,600 lb).
These changes resulted in the modified aircraft being ordered into production at the GAZ-34 factory in Tashkent.
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.
A total of 151 An-8s were built in Tashkent.
Variants
Izdeliye P
Antonov OKB in-house designation for the first prototype.
Izdeliye N
Antonov OKB in-house designation for a projected airliner version with a pressurized circular section cabin accommodating up to 57 passengers.
An-8
The initial production version.
An-8M
Projected Anti-Submarine Warfare variant.
An-8T
A fuel transporter used for all kinds of automotive fuels, as well as aircraft and rocket fuels, including two 5,300 litre (1,100 imp gal) tanks for petroleum products, or a single 5,000 litre tank for rocket oxidizers like red fuming nitric acid (RFNA), nitric acid, or a liquid oxygen flask.
An-8RU
One aircraft fitted in 1964 with two rocket boosters to increase the single engined MTOW to 42 tonnes (93,000 lb).
This project was abandoned after the crash of the first prototype during trials.
