The Ilyushin Il-4 (DB-3F) (;

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twin-engined long-range bomber and

torpedo bomber A torpedo bomber is a military aircraft designed primarily to attack ships with aerial torpedoes. Torpedo bombers came into existence just before the World War I, First World War almost as soon as aircraft were built that were capable of carryin ...

, widely used by the

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and

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during

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Design and development

In 1938, the Ilyushin design bureau redesigned the Ilyushin DB-3 to ease production and improve its performance, the revised version receiving the designation DB-3F (''Forsirovanniye'' or "boosted"). The aircraft's internal structure, particularly the wings, was extensively changed, eliminating the need for hand finishing of the structure, and with

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replacing the large scale use of steel in the earlier version.''Air International'' March 1986, p. 133.Gunston 1995, pp. 100–101. The aircraft's fuel system was redesigned, increasing its internal capacity while reducing the number of fuel tanks. The fuselage nose was lengthened to give more room for the navigator/bombardier while reducing drag. The prototype DB-3F, powered by the same Tumansky M-87B engines of the DB-3M, was piloted on its maiden flight by Vladimir Kokkinaki on 21 May 1939.Gordon, Komissarov and Komissarov 2004, pp. 91–92. It successfully passed through state acceptance tests and entered production in January 1940, with the Tumansky M-88 quickly replacing the M-87.Gordon, Komissarov and Komissarov 2004, p. 92.Gunston 1995, p. 102. The DB-3F was redesignated Il-4 in March 1942. Some series had wooden outer wings and front fuselages to conserve

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

s, and throughout the production,

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...

s and fuel tanks were upgraded for improved performance while retaining the same range. However the most notable change was the addition of larger defensive guns in the

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, using the 12.7 mm (0.5 in) UBT machine gun in place of the earlier 7.62 mm (0.3 in) weapons. In addition, it was found that the gunners were attacked first, so blocks of

armor Armour (Commonwealth English) or armor (American English; see American and British English spelling differences#-our, -or, spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, e ...

were placed around the gunner positions. This extra weight was not offset by the newer engines however, and the Il-4 proved to be slower than the earlier versions at only 404 km/h (251 mph). An attempt to improve performance was made as the Il-6, adding large

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s and heavier armament. The engines proved unreliable and production was never started. The Il-4 remained in production until 1945, when just over 5,200 had been built.

Operational history

Soviet Union

Although the Il-4 was only a medium bomber, it had the range to be used on strategic missions. The use of the bombers in this role was not a priority for the VVS, but nevertheless the Il-4 was used on several long-range bombing raids against

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in 1941. Most would be used on much shorter range missions, often adding another 1,000 kg (2,204 lb) of

bomb A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechan ...

s under the wings, in addition to the internal 2,500 kg (5,512 lb).

Finland

Finland bought four captured DB-3Fs from German stocks. These were given the Finnish Air Force serials DF-22 to DF-25 and flown from

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to Finland (one aircraft, DF-22, was destroyed en route and crashed near Syeschtschinskaya airfield). The aircraft were later flown by No. 48 Sqn during 1943 (DF-23, DF-24 and DF-25), No. 46 Sqn during 1944 (DF-23 and DF-24) and No. 45 Sqn for a short time in 1945 (DF-23), until the last remaining serviceable aircraft went into depot on 23 February 1945. After the war, DF-25 was lost in a snowstorm, landed on the ice and crashed into the woods in Öja near the city of

Kokkola Kokkola (; , ) is a town in Finland and the regional capital of Central Ostrobothnia. It is located on the west coast of the country, on the Gulf of Bothnia. The population of Kokkola is approximately , while the Kokkola sub-region, sub-region h ...

. Most parts of the plane were rescued and taken to a depot.

Operators

;: * Chinese Nationalist Air Force 24 aircraft ; *

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11 aircraft of the type DB-3M and four aircraft of the type DB-3F (Il-4) ; * ''

Luftwaffe The Luftwaffe () was the aerial warfare, aerial-warfare branch of the before and during World War II. German Empire, Germany's military air arms during World War I, the of the Imperial German Army, Imperial Army and the of the Imperial Ge ...

'' (tests only) ; *

:Regiments as at 1945-46: :10th Guards Bomber Aviation Regiment :290th Bomber Aviation Regiment :303rd Bomber Aviation Regiment (Zavitinsk, Amur Oblast) :442nd Bomber Aviation Regiment (Belogorsk, Amur Oblast) with Il-4 :other regiments *

Specifications (Il-4)

References

Notes

Bibliography

* "From DB-3 To Il-4...The Soviet Long-Range Bomber: Part Two". ''

Air International ''AIR International'' is a British aviation magazine covering current defence aerospace and civil aviation topics. It has been in publication since 1971 and is currently published by Key Publishing Ltd. History and profile The magazine was fir ...

'', Vol. 30, No. 3, March 1986. Bromley, UK: Fine Scroll. ISSN 0306-5634. pp. 133–138, 154–155. * Gordon, Yefim and Khazanov, Dmitri. ''Soviet Combat Aircraft of the Second World War, Volume 2: Twin-Engined Fighters, Attack Aircraft and Bombers''. Earl Shilton, UK: Midland Publishing Ltd., 2006. * Gordon, Yefim, Dmitriy Komissarov and Sergey Komissarov. ''OKB Ilyushin: A History of the Design Bureau and its Aircraft''. London: Ian Allan, 2004. . * Gunston, Bill. ''The Osprey Encyclopedia of Russian Aircraft 1875–1995''. London: Osprey, 1995. . * Keskinen, Kalevi; Stenman, Kari and Niska, Klaus. ''Suomen Ilmavoimien Historia 9, Venäläiset Pommittajat (Soviet Bombers)''. Espoo, Finland: Tietoteos, 1982. . * Nowarra, Heinz J. and Duval, G.R. ''Russian Civil and Military Aircraft, 1884-1969''. London: Fountain Press Ltd., 1971. . * Stapfer, Hans-Heiri. ''Ilyushin Il-4 in Action (aircraft number 192)''. Carrollton, Texas: Squadron/Signal Publications, Inc., 2004. . {{Authority control Il-004 1930s Soviet bomber aircraft Low-wing aircraft Aircraft first flown in 1936 Twin piston-engined tractor aircraft Aircraft with retractable conventional landing gear