Antonov An-124 Ruslan
The Antonov An-124 Ruslan is a large, strategic airlift, four-engined aircraft that was designed in the 1980s by the Antonov design bureau in the Ukrainian SSR of the Soviet Union. The An-124 is the world's second heaviest gross weight production cargo airplane and heaviest operating cargo aircraft, behind the destroyed one-off Antonov An-225 Mriya. The An-124 remains the largest military transport aircraft in service.
In 1971, design work commenced on the project, which was initially referred to as Izdeliye 400, at the Antonov Design Bureau in response to a shortage in heavy airlift capability within the Military Transport Aviation Command arm of the Soviet Air Forces. Two separate final assembly lines plants setup for the aircraft, one at Aviastar-SP in Ulyanovsk, Russia and the other was the Kyiv Aviation Plant AVIANT, in Ukraine. Assembly of the first aircraft begun in 1979; the An-124 performed its maiden flight on 24 December 1982. The type made its first appearance in the Western world at the 1985 Paris Air Show. Viktor Tolmachev was the Chief engineer of An-124 and An-225. After the dissolution of the Soviet Union, commercial operations were quickly pursued for the An-124, leading to civil certification being obtained by Antonov on 30 December 1992. Various commercial operators opted to purchase the type, often acquiring refurbished ex-military airlifters or stored fuselages rather than new-build aircraft.
By July 2013, 26 An-124s were reportedly in commercial service while a further ten airlifters were on order. During 2008, it was announced that Russia and Ukraine were to jointly resume production of the type. At one point, it looked as if Russia would order 20 new-build airlifters. However, in August 2014, it was reported that the planned resumption of manufacturing had been shelved due to the political tensions between Russia and Ukraine. In 2019, there were 26 An-124s in commercial service.
Development
Background
During the 1970s, the Military Transport Aviation Command arm of the Soviet Air Forces had a shortfall in strategic heavy airlift capacity. Its largest aircraft consisted of about 50 Antonov An-22 turboprops, which were used heavily for tactical roles. A declassified 1975 CIA analysis concluded that the USSR did "...not match the US in ability to provide long-range heavy lift support." Soviet officials sought not only additional airlifters, a substantial increase in payload capacity was also desirable so that the same task could be completed with fewer trips.In 1971, design work on the project commenced at the Antonov Design Bureau; the lead designer of the An-124 was Viktor Tolmachev. During development, it was known as Izdeliye 400 in house, and An-40 in the West. The design produced broadly resembled the Lockheed C-5 Galaxy, an American strategic airlifter, but also incorporated numerous improvements, the greater use of carbon-fibre composites in its construction and the more extensive use of titanium being amongst these benefits. Aluminium alloys make up the primary material used in its construction, limited use of steel and titanium alloys were also made. Unlike the C-5, it lacks a fully-pressurised cargo bay or the ability to receive fuel in-flight.
In 1973, the construction of the necessary facilities to produce the new airlifter began. Two separate final assembly lines plants were established to produce the airlifter: the company Aviastar-SP in Ulyanovsk, Russia and by the Kyiv Aviation Plant AVIANT, in Ukraine. Furthermore, the programme used components, systems, and various other elements drawn from in excess of 100 factories across the Eastern world. In 1979, manufacturing activity on the first airframe began.
On 24 December 1982, the type performed its maiden flight. Three years later, the An-124 made its first appearance in the Western world when an example was displayed at the 1985 Paris Air Show. Following the fall of the Soviet Union, commercial operations of the An-124 became an increasingly important area of activity; to this end, civil certification was sought for the type by Antonov; this was issued on 30 December 1992.
Post-Soviet developments
Sales of the An-124 to various commercial operators proceeded throughout the 1990s and into the mid 2000s; many of these were former military aircraft that were refurbished by Antonov prior to delivery, or unfinished fuselages that had been preserved, rather than producing new-build aircraft. During the early 2000s, the cargo operator Volga-Dnepr opted to upgrade its An-124 freighter fleet, these works included engine modifications to conform with chapter four noise regulations, various structural improvements that increased service life, and numerous avionics and systems changes to facilitate four person operations, reducing the crew needed from six or seven.During April 2008, it was announced that Russia and Ukraine had agreed to resume the production of the An-124 in the third quarter of 2008. One month later, a new variant — the An-124-150 — was announced; it featured several improvements, including a maximum lift capacity of 150 tonnes. However, in May 2009, Antonov's partner, the Russian United Aircraft Corporation announced it did not plan to produce any An-124s in the period 2009–2012. During late 2009, Russian President Dmitry Medvedev ordered production of the aircraft resumed; at this point, Russia was expected to procure 20 new-build An-124s. In August 2014, Jane's reported that, Russian Deputy Minister of Industry and Trade Yuri Slusar announced that production of the An-124 had been stopped as a consequence of the ongoing political tensions between Russia and Ukraine.
In late 2017, multiple An-124s were upgraded by the Aviastar-SP plant in Ulyanovsk, Russia, three of which were reportedly scheduled to return to flight during the following year. As Russia–Ukraine relations continued to sour, Antonov begun to source new suppliers while also pushing to westernize the An-124. During 2018, the American engine manufacturer GE Aviation was studying reengining it with CF6s for CargoLogicAir, a Volga-Dnepr subsidiary. It was believed that this would likely provide a range increase; as Volga-Dnepr Group operated 12 aircraft, the change would imply purchasing between 50 and 60 engines with spares. The Russian engine specialist Aviadvigatel also indicated that a further development of its PD-14, which was intended for use on an upgraded model of the Russian-manufactured An-124, designated PD-35, generated 50% more power than the present Ukrainian Progress D-18T engines.
During January 2019, Antonov revealed its plans to restart production of the An-124 without support from Russia.
Russian replacement design
At MAKS Air Show in 2017, the Central Aerohydrodynamic Institute announced its An-124-102 Slon design to replace the similar An-124-100. The design was detailed in January 2019 before wind tunnel testing scheduled for August–September. It is intended to be produced at the Aviastar-SP factory in Ulyanovsk. It should transport over , or over at. The Russian MoD wants a range of with five Sprut-SDM-1 light tanks and their 100 crew, or 300 armed soldiers.The planned An-124-102 is larger at 82.3 m long from, with an span versus and high compared with. A new higher aspect ratio, composite wing and a airframe would allow a gross weight. It should be powered by Russian PD-35s developed for the CR929 widebody, producing up from. Two fuselages are planned, one for Volga-Dnepr with a width of from the An-124's, and one for the Russian MoD of wide to carry vehicles in two lines.
On 5 November 2019, the TsAGI released pictures of a long and wide model, ahead of windtunnel testing. On 26 March 2020, TsAGI released new pictures of a wind tunnel model, announcing that the researchers of the Institute had completed the first cycle of aerodynamic testing; the results confirmed the characteristics laid down during preliminary studies.
Design
The Antonov An-124 Ruslan is a large, strategic airlift, four-engined aircraft. An aircraft with a similar role, it externally bears numerous similarities to the American Lockheed C-5 Galaxy, having a double fuselage to allow for a rear cargo door that can open in flight without affecting structural integrity, as well as the arrangement of flight control surfaces, such as the slats, flaps, and spoilers, resembling the layout of the C-5. The An-124 has a slightly shorter fuselage, has a slightly greater wingspan, and is capable of carrying a 17 percent larger payload. In place of the C-5's T-tail, the An-124 is furnished with a conventional empennage, similar in design to that of the Boeing 747. The An-124 features a fly-by-wire control system. This is a hybrid control system, as it also implements conventional mechanical controls for some aspects; these have been arranged in a manner that provides redundancy against the failure of a single hydraulic circuit.A single An-124 is capable of carrying up to of cargo internally in a standard military configuration; it can also carry 88 passengers in an upper deck behind the wing centre section. The forward area of this upper deck is where the flight deck and the crew are accommodated; movement between the upper and lower decks is via a pair of foldable internal ladders. The cargo compartment of the An-124 is, ca. 20% larger than the main cargo compartment of the C-5 Galaxy, which is. Largely due to the limited pressurisation of its main cargo compartment, the airlifter has seldom been used to deploy paratroopers or to carry passengers, as they would typically require oxygen masks and cold-weather clothing in such conditions. In comparison, the upper deck is fully pressurised. The floor of the cargo deck is entirely composed of titanium, a measure that is usually prohibited by the material cost. It is suitable for carrying almost any heavy vehicle, including multiple main battle tanks.
The An-124 is powered by four Lotarev D-18 turbofan engines, each capable of generating up to 238–250 kN of thrust. To reduce the landing distance required, thrust reversers are present. Pilots have stated that the airlifter is relatively light on the controls and is easy to handle for an aircraft of its size. A pair of TA18-200-124 auxiliary power units are accommodated within the main landing gear fairings. As a consequence of the heat and blast effects produced by these APUs, some airports require pavement protection to be deployed. The landing gear of the An-124 is outfitted with an oleo strut suspension system for its 24 wheels. This suspension has been calibrated to allow for landing on rough terrain and is able to kneel, which allows for easier loading and unloading via the front cargo door. Other features intended to ease loading including an onboard overhead crane in the cargo deck, capable of lifting up to 30 tonnes, while items up to 120 tonnes can be winched on board. Two separate radar units are typically present, one is intended for ground mapping and navigation purposes, while the other is for weather.