The Antonov An-70 (Ukrainian: Антонов Ан-70) is a four-engine medium-range transport aircraft, and the first aircraft to take flight powered only by propfan engines. It was developed in the late 1980s by the Antonov Design Bureau to replace the obsolete An-12 military transport aircraft. The maiden flight of the first prototype took place in December 1994 in Kyiv, now independent Ukraine. Within months the prototype had suffered a mid-air collision. A second airframe was produced to allow the flight-test programme to proceed. Both prototypes were produced by the Kyiv Aircraft Production Plant. Following the dissolution of the Soviet Union in the early 1990s, the programme became a joint development between Russia and Ukraine. The former compounded the issue of a reduced market with its intermittent commitment to the project. Repeated attempts to start production have had limited success. Western European countries, including Germany, at one stage assessed the aircraft for procurement, but many later decided against it. The An-70 is a monoplane with a high-mounted wing design that features four distinctive propfan engines. Designed by the Progress Design Bureau, each of the D-27 engines is rated at 13,800 shp (which can be uprated to 16,000 shp), which is used to drive the SV-27 contra-rotating scimitar propellers designed by Aerosila; eight on the front propeller and six on the aft propeller. The propfan engines deliver slipstream to the supercritical wings that feature double-slotted trailing edges to provide high lift coefficients at low speeds. The modernisation of the aircraft during 2010–12 saw upgrades to the engines, including the incorporation of FADEC, and the further separation of the two propellers. The aircraft's cruise speed is 750 km/h (405 kt) at an operational altitude of 8,600 to 9,600 m (28,200 to 31,500 ft); Antonov claimed in 1997 that the aircraft had a design maximum speed of 850 km/h (460 kt, or Mach 0.8), which would have compared favourably with Mach 0.77 of the larger turbofan-powered C-17. According to DASA's evaluation, the propfan engines were 10 percent more efficient than conventional turboprops. Similar to many aircraft designs of the Soviet Union, the An-70 was designed as an airlifter that could operate from unprepared fields. In short take-off and landing (STOL) configuration, the aircraft could lift off from a 600 m (2,000 ft) dirt strip with 25 tonnes (55,000 lb) of cargo and fly for 3,000 km (1,900 mi). Alternatively, it could fly the same distance with 35 t (77,000 lb) of cargo if it took off from a 1,800 m (5,900 ft) paved runway. For a payload-heavy mission, the An-70 can haul 47 t (104,000 lb) of cargo for a range of 1,500 km (930 mi), but if range was essential, the aircraft can carry a load of 17 t (37,000 lb) over 8,000 km (5,000 mi). In exceptional circumstances, the An-70 subjected to lower-g take-offs, can airlift a 47-tonne (104,000 lb) T-80U main battle tank and fly it for 3,000 km (1,900 mi). The fully pressurised internal cabin measures 4 m (13 ft) wide and 4.1 m (13 ft) high, and has a length of 18.6 m (61 ft) from the front to the ramp; with the ramp included, the total cabin length is 22.4 m (73 ft). In comparison, the turbofan-powered Il-76 has a lower cross-sectional cargo area, but exceeds the An-70 in payload capability and ramp length. The An-70's cargo hold is serviced by four electrical hoists that facilitate autonomous cargo loading. A central floor can be rapidly installed for the accommodation of 300 soldiers or 200 injured personnel over two decks. For more details of the development, design and variants, click here.
