The Antonov Giants: An-22, An-124, & An-225

The Soviet Union had a certain admiration for the virtue of sheer impressive size, and this bias was reflected in aircraft design. The most spectacular examples are three of the largest aircraft ever built, all products of the Antonov design bureau: the "An-22 Antheus (Cock)", the "An-124 Ruslan (Condor)", and the "An-225 Mriya (Cossack)" cargolifters. This document provides a history and description of these Antonov giants.

Antonov An-22 Antheus ("Cock")

On 16 June 1965, the Soviet Union impressed Western observers by flying in the prototype of a new cargolifter aircraft, the Antonov "An-22 Antel (Antheus)", to the Paris Air Show. The new transport was indisputably the biggest aircraft in the world. The An-22 had performed its first flight only months before, on 27 February 1965.

By 1967, the initial prototype that made its debut in Paris had been followed by four more prototypes and the first production item. The Soviets were proud of their impressive big machine, demonstrating it in public air displays in the USSR and announcing that it had set a number of payload-to-height records.

Observers recognized that the new machine was clearly a scaled up An-12 "Cub", with both machines being four-engine turboprops with a high mounted, straight, narrow-chord wing. Both aircraft also featured main landing gear mounted in fairings along the fuselage, with a pressurized crew compartment and unpressurized cargo compartment.

There were also clear differences between the two beyond their difference in size. Unlike the An-12, the An-22 used four-bladed contrarotating propellers, driven by Kuznetsov NK-12MA turboprop engines with 11.2 kW (15,000 SHP) each. The An-22 also featured twin tailfins, instead of the An-12's large single tailfin. The twin tailfins gave the An-22 better handling with an engine out, and a single tailfin would have been much too tall anyway.

The narrow-chord wing of the An-22 meant that the total wing area was low and so the wing loading was unusually high for a cargolifter, but the wing had double slotted flaps over 60% of its length, and the An-22 could take off in 1,400 meters (4,265 feet) in fully-loaded condition.

The An-22 was designed for rough-field operation, with two-wheel nosegear and three levered-suspension dual main landing gear assemblies in each fairing, for a total of six main gear assemblies and twelve main gear wheels. The aircrew could adjust tire pressure from the cockpit to compensate for field conditions.

There were five or six crew, plus a pressurized compartment behind the cockpit with seating for 28 or 29 passengers. Personnel access was through a door in each landing gear fairing. The main cargo bay was 33 meters (108 feet) long, and was accessed through a rear loading ramp. The ramp could be opened in flight for airdrop of cargoes. Cargo capacity was 80 tonnes (88 tons). There were four traveling gantries mounted on rails in the roof of the cargo bay, to be used in conjunction with two winches, each with a load capacity of 2,500 kilograms (5,500 pounds).

An array of three radars were fitted with radomes under the nose for navigation and weather warning, and like most Soviet transports, there was glazing under the nose for the navigator.

Apparently about 100 An-22s were built to end of production in 1974, with the totals split evenly between Aeroflot and the VTA, the Soviet military airlift service, though some sources claim that even the Aeroflot machines were generally used for military duties. Some of the five prototypes were upgraded to production specification and put into formal service.

The An-22s were used mostly to carry cargoes to the undeveloped Soviet Far East. The Antonov bureau considered building a double-decker airliner version of the An-22, with a capacity of 724 passengers, but this machine never got beyond design studies.

The An-22 was supplemented by the Antonov An-124, discussed below, beginning in 1987. It is unclear how many An-22s still remain in service, maybe about a dozen or two dozen in all, but they do continue to fly the occasional heavy-lift mission.

Antonov An-124 Ruslan ("condor")

In 1968, the US flew the first Lockheed "C-5A Galaxy" cargolifter, which took the title of "world's biggest aircraft" away from the An-22. The USSR was of course inclined to reply, to the extent that need justified it and the resources were available, and in the summer of 1977 reports indicated that the Soviets were in fact working on a mega-sized jet cargolifter.

The initial prototype of the new aircraft performed its first flight in December 1982. Although the NATO rumor mill had assigned the type the designation "An-40" and then "An-400", along with the NATO codename "Condor", in 1985 the big jet was announced as the "An-124 Ruslan". The aircraft entered service in early 1986.

The An-124 had a general configuration similar to that of the C-5A, with a high-set swept wing mounting four high-bypass turbofans on pylons, with front and rear loading. The most significant visible difference from the C-5A was that the An-124 had a conventional low-set tailplane, in contrast to the tee tail of the C-5A. Although the dimensions of the two aircraft were similar, the An-124 had a greater empty weight than the C-5A and a substantially greater cargo capacity.

The An-124 had very heavy-duty landing gear for rough field operation. The nose gear consisted of two twin-wheel units mounted in parallel, with each unit steered independently. There were five sets of main landing gear units on each side of the aircraft, with dual wheels on each set, for a total of ten sets and twenty wheels. The front two units on each side were steerable. The landing gear was adjustable to allow the transport to "kneel", to assist cargo loading.

The An-124's four Lotarev D-18T turbofans provided 230 kN (23,400 kgp / 51,590 lbf) thrust each, and had thrust reversers to reduce landing roll. In conjunction with full-span leading-edge slats and large flaps, the powerful engines allowed the An-124 to operate off of rough airstrips only 1,200 meters (3,800 feet) long.

The pressurized cabin accommodated a flight crew of six, along with accommodations for a relief crew. The aircraft was flown with a quadruplex fly-by-wire flight control system, and featured a triple-redundant inertial navigation system. It did not have a glazed nose. A pressurized passenger section with 88 seats was included behind the wing.

The transport's nose lifted up to allow a folding ramp to be deployed, while the tail featured a four-section door-ramp system. The cargo hold was 26 meters (118 feet) long, 6.4 meters (21 feet) wide, and 4.4 meters (14 feet 5 inches) high. Two traveling gantries were fitted to the roof, with each gantry having a load capacity of 10,000 kilograms (22,050 pounds) and fitted with two hoists, each having a load capacity of 5,000 kilograms (11,025 pounds). Twin auxiliary power units (APUs) could be used to drive the hoist system on the ground. The aircraft could carry a load of up to 150 tonnes (165 tons).

A total of 46 Condors were built up to 1999, with 21 put into military service and 27 into civilian service. The An-124 has been a moneymaker for the Russians, since it has an unequalled cargolift capacity, and it is now carrying cargoes all over the world. In fact, business has been so good for the Condor that in mid-2000, Aviastar Aircraft began delivery of new-build "An-124-100" aircraft to the Russian cargo carrier Volga-Dnepr. These were the first new-built An-124s to be shipped since 1995, when two specialized An-124-100s were delivered to the Russian government for support of state visits. These two aircraft were later sold to the Ukraine's Antonov Airlines.

The new An-124-100s feature a much improved service life of 24,000 hours. The original An-124s were only built for a rated service life of 7,500 hours, apparently on the rationale that such a specialized aircraft would only be used intermittently. The short service life led to a protracted dispute between the Antonov organization and commercial users of the An-124. The new aircraft resolve the dispute, and a service-life extension program is now in place for older An-124s.

The service-life extension program includes airframe improvements, in particular for the cargo hold floor and cargo handling system; new avionics; a new crew rest compartment; and improved engines. The aircraft's four ZMKB Progress (previously Lotarev) D-18T turbofans, while retaining the same thrust, are now rated for a service life of 24,000 hours, still not world-class but a vast improvement over the original, pathetic service life of 1,250 hours. The new versions of the D-18T also meet international noise and nitrous-oxide emission regulations. Other new kit in the An-124-100 includes a Global Positioning System (GPS) satellite navigation receiver and a Honeywell ground proximity warning system.

The An-124 remains a product with a unique niche, and the Russian and Ukrainian organizations that build and fly the machine have lobbied their respective governments to authorize further new production. The new machines are to be built to the "An-124-100M" specification, with payload raised from 120 to 150 tonnes (132 to 165 tons), crew reduced from six to four, and improved service life. A second-stage improvement, the "An-124-100M-150", would feature 20% more range and increased service life, from 24,000 hours to 40,000 hours.

Volga-Dnepr is something of a Russian business success story. Their An-124-100s not only give the company an unmatched commercial heavy lift capability, these machines are optimized for operating under austere conditions and can fly almost anywhere if there's a landing strip long enough for them.

Possibly Volga-Dnepr's biggest single customer is the United Nations. The company has been a carrier for the UN since 1994, operating in peacekeeping operations over much of the world. The UN connection gets Volga-Dnepr additional business because nations working in specific peacekeeping operations often take advantage of the company's presence and charter them to fly other cargoes.

Volga-Dnepr was a major player in Afghanistan in 2001:2002, flying hundreds of cargoes for the UN, the World Food Program, the US military, and other organizations. Afghanistan was a particularly demanding scenario for the company. Not only were conditions very primitive, but the aircraft had to operate in "hot and high" conditions into airfields surrounded by jagged mountains, presenting a real challenge to pilots.

Antonov An-225 Mriya ("cossack")

Even as the An-124 was going into service, the Antonov bureau was working on a specialized derivative to carry outsize cargos, usually externally. The primary loads were intended to be elements of the Soviet "Energia" heavy-lift space booster series, including the "Buran" manned space shuttle.

The result, the "An-225 Mriya (Dream)" performed its first flight in 1988, and appeared at the Paris Air Show in 1989 with a Buran shuttle on its back. The An-225 was clearly a derivative of the An-124, with fore and aft fuselage plugs to extend length, and wing inserts to extend span and allow carriage of two more Lotarev D-18T turbofans, for a total of six engines.

The number of main landing gear assemblies was increased from five per side to seven to handle the increased takeoff weight. A set of standoffs were fitted to the back for external cargo carriage, with the standoffs covered by fairings when not in use, and the conventional tail assembly of the An-124 was changed to a twin-fin assembly to ensure controllability when a large cargo was mounted on the back. The rear loading ramp was deleted to reduce weight.

The An-225 can lift cargoes with a weight of up to 250 tonnes (275 tons). Since it was not intended for any tactical role, it was not designed for short-field operation, and has a takeoff length of 3,500 meters (11,500 feet) with maximum payload.

The An-225 is the world's biggest aircraft by far. Since it is a specialized machine, it is unlikely that there would have been reason to build it in large numbers in the best of circumstances. Given that the introduction of the big cargolifter coincided with the last days of the Soviet Union, it is not surprising that only two were built.

However, since the An-124 has proven profitable in the commercial heavy-lift market, the An-225 is now being offered for the same work. The Antonov bureau has refurbished one of the An-225s for commercial operations, including transport of bulky cargoes and possibly air launch of space boosters. The update program involves the addition of modern navigation and communication avionics, a collision avoidance system, and modifications to reduce the noise signature of the aircraft. First flight of the modified An-225 was on 7 May 2001. If the An-225 proves commercially successful, Antonov may update the other An-225 as well.

Along with the modest improvements to the An-124 being considered for new production of the aircraft, the Antonov organization is also investigating a more ambitious cargolifter, an improved hybrid of the An-124 and An-225 called the "An-124-300". It would feature the fuselage of the An-124 and the extended wing of the An-225, kitted up with modern avionics and engines. Since more powerful engines are now available, only four would be needed instead of six. The cargo floor would be extended and a palletized loading system would be installed. It would have a maximum range of 11,500 kilometers (7,145 miles) with a 100 tonne (110 ton) cargo. Development costs were cited as less than a billion USD.

Author: Greg Goebel