Antonov An-2
The Antonov An-2 is a Soviet mass-produced single-engine biplane utility/agricultural aircraft designed and manufactured by the Antonov Design Bureau beginning in 1947. Its durability, lifting power, and ability to take off and land from poor runways have given it a long service life. The An-2 was produced up to 2001 and remains in service with military and civilian operators around the world.
The An-2 was designed as a utility aircraft for forestry and agriculture, but the basic airframe is adaptable and numerous variants have been developed. These include hopper-equipped crop-dusters, scientific versions for atmospheric sampling, water-bombers for fighting forest fires, air ambulances, seaplanes, and versions for dropping paratroopers.
The most common version is the An-2T 12-seater passenger aircraft. All versions are powered by a nine-cylinder Shvetsov ASh-62 radial engine.
Design and development
Origins
The Antonov An-2 was designed to meet a 1940s Soviet Ministry of Forestry requirement to replace the smaller Polikarpov Po-2, which was used in large numbers in both agricultural and utility roles. Antonov designed a large single bay biplane of all-metal construction, with an enclosed cockpit and a cabin with seats for twelve passengers. The first prototype, designated SKh-1, powered by a Shvetsov ASh-21 radial engine, flew on 31 August 1947 from Yeltsovka Airport in Novosibirsk Oblast, Russia. The second prototype was fitted with a more powerful Shvetsov ASh-62 engine, which allowed the aircraft's payload to be increased from, and in this form saw production.Initial production was at State Factory 473 in Kiev, Ukrainian SSR, where the majority of up to 5,000 units had been produced by 1960. Later Soviet production was at State Factory 464 at Dolgoprudniy, Russian SFSR. After 1960, most An-2s were constructed at Poland's WSK factory in Mielec. It is believed that over 13,000 were built in Poland before manufacturing ended in 1991.
Until 2001, limited production was undertaken using remaining stocks of spares, including a small batch of four aircraft that were produced for Vietnam. China also builds the An-2 under licence as the Shijiazhuang Y-5. It has been erroneously reported that there was East German production of the An-2; while An-2s often underwent extensive refurbishment in East German facilities, no new aircraft were built there.
The An-2 is commonly used as a light utility transport, parachute drop aircraft, agricultural work and other tasks suited to a large slow biplane. Its slow flight and good short field performance make it suited for short, unimproved fields, and some specialized variants have also been built for cold weather and other extreme environments. The Guinness Book of World Records states that the 45-year production run for the An-2 was for a time the longest for any aircraft and challenged the over two decade-long run of the 1920s Polikarpov Po-2 it replaced. The An-2's record has since been exceeded.
Further development
During the early 1980s, Antonov experimented with an An-2 powered by a Glushenkov turboprop engine. Aircraft with this engine had a longer, streamlined nose. It received the designation An-3.During 2013, Antonov announced that it had flown a new An-2 version, the An-2-100, with a three-blade reversible propeller and a Motor Sich MS-14 turboprop running on kerosene rather than Avgas, which is no longer produced in CIS countries. That same year, the company stated that it had received orders for upgrading hundreds in Azerbaijan, Cuba and Russia to the An-2-100 version.
The Siberian Research Institute of Aviation test flew a modified An-2 with winglets and a carbon fibre wing structure. It was equipped with a turboprop engine with a five bladed propeller. According to Russian aviation company Sukhoi, this aircraft was a demonstrator for an An-2 replacement announced on 10 June 2015. The carbonfibre composite materials, including wing panels, spars and ribs were produced by the Novosibirsk Aviation Plant. Sukhoi says the design change increased its speed by 50%.
Design
The An-2 is a mass-produced single-engine biplane that was deliberately furnished with a minimum of complex systems. The wing leading edge slats that give the aircraft its slow flight ability are fully automatic, being held shut by the airflow over the wings. When airspeed drops below, elastic rubber springs extend the slats. Under typical conditions, take-off can be made within while the landing run requires. These figures vary dependent on weight, air temperature, runway surface, and wind direction.The An-2 is equipped with features which make it suitable for operation in remote areas with unimproved airstrips. It is fitted with a pneumatic brake system similar to those used on heavy trucks to stop on short runways, along with an air line attached to the compressor, so the pressure in the tires and shock absorbers can be adjusted. The batteries, while sizable, are easy to remove, and it does not need a ground power unit for starting the engine. Likewise, there is no need for an external fuel pump to refuel the aircraft as it is provided with its own.
The operating handbook does not explicitly specify a stall speed, stating instead: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about and when the airplane slows to a forward speed of about, the airplane will sink at about a parachute descent rate until the aircraft hits the ground."
The low stall speed makes it possible for the aircraft to fly backwards relative to the ground under high wind conditions while under control.
Many western countries prohibit the use of the An-2 commercially because the aircraft has not been certified by the relevant national aviation authorities. These restrictions vary by country, but all prevent the An-2 being used for any commercial purpose, with the exception of the United States, where PZL-built An-2s are exempt from this restriction due to a bilateral agreement with Poland. Other An-2s are operated non-commercially under an experimental certification.
Operational history
Military service
The An-2 was operated in large numbers by the Soviet Air Force and Eastern Bloc forces. Its first military use was during the Korean War of the early 1950s.The Vietnam People's Air Force operated the An-2 during the Vietnam War and occasionally used the type as an attack aircraft. During the 1960s, a single An-2 that was engaging South Vietnamese naval units was shot down by a United States Air Force McDonnell Douglas F-4 Phantom II fighter.
On 12 January 1968, a clandestine TACAN site installed by the United States Air Force in Northern Laos for directing USAF warplanes flying from Thailand to Vietnam was attacked by three North Vietnamese An-2s. A pair of An-2s fired on the outpost using a mixture of machine guns and rockets while a third An-2 orbited overhead. An Air America Bell UH-1B resupplying the site gave chase to the attacking aircraft. Using an AK-47, the American crew succeeded in shooting down one of the An-2s while the second aircraft was forced down by combined ground and air fire, eventually crashing into a mountain. The surviving Antonov returned to its home base, Gia Lam, near Hanoi.
During the Croatian War of Independence in 1991, a number of elderly An-2s previously used for crop-spraying were converted by the Croatian Air Force to drop makeshift barrel bombs. They were also used to conduct supply missions to besieged parts of Croatia.
The chief advantage of the An-2 was its ability to operate from small improvised airstrips. They frequently dropped supplies by parachute to isolated garrisons. At least one An-2 was shot down on 2 December 1991 over Vinkovci, eastern Slavonia, by a Serbian salvo of SA-6 surface to air missiles.
North Korea has also operated An-2s. The Korean People's Army Special Operation Force has used the An-2 to infiltrate paratroopers.
During the 2020 Nagorno-Karabakh war, Azerbaijan operated unmanned An-2s for surveillance and bombing of Armenian defenses, however the type of the drone was unknown as of October 2020. Armenian forces revealed footage of the alleged shootdown of an Azerbaijani An-2, according to video evidence at least 11 An-2 have been destroyed, with 10 confirmed as shot down and one crashing after takeoff.
On March 2, 2022, Russian An-2s were observed at Seshcha Air Base, Bryansk Oblast. As the base is close to the Ukraine border, it was speculated that the aircraft were to be used in the 2022 Russian invasion of Ukraine.
Civil aviation
Over the years, dozens of nations and companies have employed the An-2 in civil roles. The type was heavily used throughout the Soviet Union and the Eastern Bloc nations. In particular, the Russian airline Aeroflot operated a large number of them. The An-2 was used as a short-range airliner, and in Estonia, made regular flights between the towns of Kuressaare and Kärdla, which are on separate islands, Saaremaa and Hiiumaa.Since the collapse of the Soviet Union, most airlines in these regions have been retiring their An-2s, as some were over 40 years old, as well as a result of the decline in the production of avgas to fuel the type. Private operators are still using An-2s, as they remain popular for some functions, such as for skydiving.
High noise levels, maintenance costs and fuel consumption has rendered them obsolete for the majority of commercial routes in Europe, but the large number available mean that unit prices are low in comparison to alternatives. Price has made them attractive in the developing world, where their abilities makes them an asset to airlines on a budget. Many ex-Aeroflot An-2s have found work with regional operators across Africa, Central and South America, Cuba and southeast Asia.
As of 2015, there were thousands of An-2s in operation around the world, including over 1,500 in Russia, 294 in Kazakhstan and 54 in Ukraine.
In September 2024, Vladimir Putin ordered the UZGA LMS-901 Baikal aircraft into production as a replacement. However, certification of that aircraft's Klimov VK-800SM engine is not expected until 2025, with engine deliveries not starting until 2026.