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Antonov An-2
The Antonov An-2 (Russian nickname: "Annushka"
or "Annie"; "kukuruznik" - corn crop duster) is a Soviet
mass-produced single-engine biplane utility/agricultural aircraft
designed and manufactured by the Antonov Design Bureau (now State
Company) since 1946. (USAF/DoD reporting name Type 22, NATO
reporting name Colt.)
The An-2 is used as a light utility transport,
parachute drop aircraft, agricultural work and many other tasks
suited to this large slow-flying 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 ever, for any aircraft, but it was recently
exceeded by the Lockheed C-130 Hercules.
The Antonov An-2 was designed to meet a 1947
Soviet Ministry of Forestry requirement for a replacement for the
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 room for seats accommodating twelve passengers. The
first prototype, designated SKh-1 and powered by a Shvetsov ASh-21
radial engine, flew on 31 August 1947. The second prototype was
fitted with a more powerful Shvetsov ASh-62 engine, which allowed
the aircraft's payload to be significantly increased from 1,300 to
2,140 kg (2,870 to 4,720 lb), and in this form it was ordered into
production.
Initial Soviet production was at State Factory
473 in Kiev, Ukrainian SSR where the bulk of up to 5,000 units had
been produced by 1960. Later Soviet production (after 1965, of
model An-2M especially) was at State Factory 464 at Dolgoprudniy,
Russian SFSR. After 1960, however, most An-2s were been built at
Poland's WSK factory in Mielec, with over 13,000 made there before
full production ended in 1991. Limited production from parts
stocks, as well as spares and maintenance coverage continued until
2001, when four aircraft were produced for Vietnam. China also
builds the An-2 under licence as the Shijiazhuang Y-5. It has been
occasionally and erroneously reported that there was East German
production of the An-2. While An-2s were extensively refurbished in
East Germany, there were no new aircraft built there.
The An-2 was designed as a utility aircraft for
use in forestry and agriculture. However, the basic airframe is
highly adaptable and numerous variants have been developed. These
include hopper-equipped versions for crop-dusting, scientific
versions for atmospheric sampling, water-bombers for fighting
forest-fires, flying ambulances, float-equipped seaplane versions
and lightly armed combat versions for dropping paratroops. The most
common version is the An-2T 12-seater passenger aircraft. All
versions (other than the An-3) are powered by a 750 kW (1,010 hp)
nine-cylinder Shvetsov ASh-62 radial engine, which was developed
from the Wright R-1820. It uses 43 gallons of avgas per hour.
It has a pneumatic brake system (similar to
those used on heavy road vehicles) to stop on short runways.
It has an air line fitted to the compressor, so the pressure in the
tires and shock absorbers can be adjusted without the need for
special equipment.
The batteries are large and easy to remove, so the aircraft does
not need a ground power unit to supply power.
There is no need for an external fuel pump to refuel the aircraft,
as it has an onboard pump that allows the tanks to be filled from
simple fuel drums.
It has a minimum of complex systems. The crucial wing leading edge
slats that give the aircraft its slow flight ability are fully
automatic, being held closed by the airflow over the wings. Once
the airspeed drops below 64 km/h (40 mph), the slats will extend
because they are on elastic rubber springs.
Take-off run: 170 m, landing run: 215 m (these numbers will of
course vary depending on take-off/landing weight, outside air
temperature, surface roughness, and headwind).
A note from the pilot's handbook reads: "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 64 km/h (40 mph) and when
the airplane slows to a forward speed of about 40 km/h (25 mph),
the airplane will sink at about a parachute descent rate until the
aircraft hits the ground."
The An-2 indeed has no stall speed quoted in the
operating handbook. Pilots of the An-2 say one can fly the aircraft
in full control at 30 mph (as a contrast, a modern Cessna
four-seater light aircraft has a stall speed of around 50 mph).
This slow stall speed makes it possible for the aircraft to fly
backwards (if the aircraft is pointed into a headwind of, say, 35
mph (56 km/h), it will travel backwards at 5 mph (8.0 km/h) whilst
under full control). (This is also possible with almost any other
true Short Take Off and Landing (STOL) aircraft, but the Antonov
has the distinction of being able to do the trick in the mildest
headwind.)
Since the collapse of the Soviet Union and the
Eastern European communist states, most airlines in these areas
have been withdrawing their An-2s from service, as some of these
aircraft are now over 40 years old and the production of avgas had
decreased. Private operators are still using the planes, as their
stability, capacity and slow-flying ability make them very popular,
for instance for skydiving.
In the early 1980s Antonov experimented with a
development of the An-2 powered by a modern turboprop engine. The
unit used was a 1,450 horsepower (1,080 kW) Glushenkov engine and
aircraft fitted with this engine were fitted with a longer, more
streamlined nose to accommodate it. See Antonov An-3 article for
more information.
In 2013 Antonov announced that it had
successfully flown for the first time a new version of the An-2
dubbed the An-2-100 fitted with a 3-blade reversible propeller and
a 1500 shp Motor Sich MS-14 turboprop running on kerosene rather
than Avgas which is no longer produced in CIS countries.
Whilst their high noise levels, increasing
maintenance costs, high fuel consumption and unsophisticated nature
(the pre-flight checks alone take between 30 and 40 minutes) make
them obsolete for commercial service in Europe, the large number of
aircraft available means that prices are low (from as little as
US$30,000 for a serviceable example). This makes them ideal for the
developing world, where their ability to carry large loads into
short airstrips makes them assets to airlines on a budget. Many
ex-Aeroflot An-2s work as regional airliners in Africa, Central and
South America, Cuba and southeast Asia.
The An-2's ability, looks and flying
characteristics, and its status as one of the world's biggest
single-engined production biplanes, mean that demand for the An-2
is increasing in Western Europe and the United States, where they
are prized by collectors of classic aircraft, making it an
increasingly common sight at airshows. However, 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 'for profit' purpose, with the
exception of the United States, where An-2s imported since 1993 are
limited to experimental certification & Title 14 Code of
Federal Regulations, Part 21.191,21.193,21.195,91.313,91.319, but
PZL-built An-2s are exempt from this restriction due to a bilateral
agreement with Poland.
In 2013, Antonov received orders for upgrading
"hundreds" of the An-2 planes still in operation in Azerbaijan,
Cuba and Russia to the An-2-100 upgrade version.
The Siberian Research Institute of Aviation
(SIBNIA) has test flown a highly modified Antonov An-2 with
carbonfibre winglet-like braces and carbonfibre wing structures.
This is to demonstrate the aerodynamic and structural changes
planned for an An-2 replacement, Sukhoi has announced on 10 June
2015. The aircraft was equipped with a five-bladed turboprop
engine, most probably the Honeywell TPE331 already installed on a
modernized version of the An-2 that entered service in 2014. The
autoclave-cured carbonfibre composite materials – including
wing panels, spars and ribs – were produced by the
Novosibirsk Aviation Plant. Sukhoi says the design change improved
the speed of the An-2 by 50%, and testing also has shown the
minimum flying speed of the aircraft is “close to
zero”.
The An-2 was used by combat services in the
Korean War. During the 1960s an An-2 attempting to engage South
Vietnamese naval units was shot down by an F-4 Phantom II under the
control of an Air Intercept Controller (AIC) on the USS Long
Beach.
On 12 January 1968, a clandestine TACAN site
(call sign: Lima Site 85/Phou Pha Ti) installed by the United
States Air Force in Northern Laos for directing USAF warplanes
flying from Thailand to Vietnam was attacked by two North
Vietnamese An-2s using machine guns fired from the cabin, rockets
and hand thrown grenades. A third An-2 orbited overhead. An Air
America Bell UH-1B, XW-PHF, resupplying the site chased the two
attacking aircraft. By using an AK-47 the American crew (Ted Moore
Captain, Glen Wood kicker) succeeded in shooting down one of the
An-2s while the second aircraft was forced down by combined ground
and air fire and crashed into a mountain. The surviving Antonov
returned to its home base, Gia Lam, near Hanoi.
During the Croatian War of Independence in 1991,
a few old Antonov An-2 biplanes used for crop-spraying were
converted by the Croatian Air Force to drop makeshift boiler bombs
and were used in supply missions to the town of Vukovar and other
besieged parts of Croatia. The chief advantage for the An-2 was
that they could take off and land in small or improvised airstrips.
They were also used to drop supplies by parachute on isolated
garrisons. At least one was shot down on 2 December 1991 over
Vinkovci, eastern Slavonia, by Serbian SAM missiles, purportedly
SA-6s. Following the shootdown, the flights over Serbian lines
ceased, due to the presence of TV guided SA-6. The previous radar
guided AA systems were avoided by keeping the airplane's speed
below 140 km/h, the speed of objects that radars were programmed to
erase from the screen.
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