AIRCRAFT
The Antonov An-72 appears to have been developed as much for military tactical transport duties as for commercial use, although all of the aircraft displayed to date, or illustrated in the former Soviet Union, bear Aeroflot markings. It is unique as a production aircraft for its use of upper surface blowing (USB) as a means of increasing lift and thus providing STOL performance.
Before the appearance of the An-72, this configuration had been applied experimentally to several other aircraft, in particular by Boeing on its YC-14 prototypes built for USAF's AMST program. Like the YC-14, the An-72 has two high-bypass turbofans mounted in nacelles that project well ahead of the high-positioned wing. This location allows the engine exhaust to be discharged directly over the wing center section, through suitably shaped orifices, producing a Coanda effect that causes the airflow to attach itself to the wing surface, even when the large-area trailing-edge flaps are deflected downwards. The lift of the wing is thus enhanced and low-speed performance is consequently improved to produce a good STOL capability.
The large-area vertical and horizontal tail surfaces are in turn required to maintain control of the aircraft at the low speeds made possible by the high wing lift coefficient. Other features of the An-72, including its multileg main landing gear contained in fuselage side blisters and its rear-loading provisions, are indicative of the military applications and the requirement for the aircraft to operate from unprepared surfaces, whether in military or civil guise. Three prototypes of the An-72 are reported to have been built, of which one was for static trials.
The first of the two flying prototypes was airborne for the first time on Dec. 22, 1977. Eight pre-series aircraft were built. In late 1983, a series of flights made in an An-72 set a total of 17 records under conditions specified by the FAI, for aircraft in classes C1 and C1k, these being for takeoff weights up to 55,115 lb. (25,000 kg.) and up to 77,160 lb. (35,000 kg.), respectively. At the higher weight, records included a time of 27 min. 25.4 sec to 39,370 ft (12,000 m), an absolute altitude of 40,682 ft (12,400 m), and a payload of 17,778 lb (8,064 kg) lifted to 6,562 ft. (2,000 m).
The An-72 has the NATO reporting name `Coaler A'. During its flight development, the An-72 was flown with several changes to the profile of the rear fuselage. As first illustrated, it had two large ventral fins, canted out on each side of the ramp door in the rear fuselage, with two petal-type airbrakes forming the end of the fuselage.
Later, a beaver-tail rear fairing appeared, with revised ramp and door, but the production form, the An-72A, incorporates a door arrangement similar to that of the An-26, with a ramp that can be hinged down when the aircraft is on the ground, to permit easy loading and unloading of supplies, but which can also move down and forward to lie flush under the rear fuselage so that trucks can be backed up to link with the cabin floor.
The An-72A has extended wings and fuselage, relative to the prototypes. In 1984, official reference was made in the Soviet press to the An-74 (NATO 'Coaler B') an aircraft specifically developed for all-weather operations in Arctic and Antarctic regions, with wheel/ski landing gear. Its duties, according to the Soviet report include ferrying personnel and supplies for scientific stations on ice floes, air-dropping supplies to expedition teams, and icefield reconnaissance. The An-74 has two blister windows behind the flight deck and a larger nose radome.
Overall dimensions of the An-72A and A-74 are: span 104 ft 7.5 in (31.89 m) and length of 85 ft 6 in (28.07 m). MTOW is 76,060 lb (34,500 kg) off a 5,900 ft runway, dropping to 60,625 lb (27,500 kg) off a 3,280 ft (1,000 m) runway.
The An-74 has a reported maximum speed of 380 kt (705 km/h) and cruises at 297 kt (550 km/h) using the same high by-pass D36 turbofans, 14,330 lb (6,397 kg) static thrust, as the An-72. A payload of 11,023 lb (5,000 kg) can be carried over a distance of l,726 nm (3,200 km), or twice that load (the maximum payload) a distance of 620 nm (1,150 km). Maximum range is 2,537 nm (4,700 km).
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