Ilyushin IL-4 or Илью́шин Ил-4
Role Bomber, torpedo-bomber
The Ilyushin Il-4 was a Soviet World War II bomber aircraft, widely used by the Soviet Air Force (VVS, Voenno-Vozdushnye Sily) although not well known. Its NATO code-name was Bob.
One of the great bombers of the war, the Ilyushin IL-4 has not unnaturally been overshadowed in Western thinking by the great British and American aircraft, yet well over 5,000 IL-4s were produced between 1937 and 1944, the vast majority in the last three years. The original prototype of this low-wing twin-engine bomber, designated the TsKB-26, flew in 1935, was developed through the TsKB-30, and entered production in 1937 as the DB-3B (DB being a Soviet contraction denoting longrange bomber). Early examples were powered by 571kW M-85 engines, but these were replaced by 716kW M-86s in 1938. Although a tough and relatively simple design, the aircraft suffered from a poor defensive armament of single nose, dorsal and ventral 7.62mm guns, and lost heavily to such aircraft as the Bristol Bulldog, Gloster Gladiator and Fokker D.XXI during the Winter War against Finland in 1939-40. In 1939 a modified version with lengthened nose and more armour (the DB-3F) appeared, and in 1940, in conformity with changed Russian practice, the designation became IL-4 (denoting the designer, Sergei Ilyushin). Soon after the German attack on the USSR opened in 1941 it was decided to withdraw IL-4 production to newly opening plants in Siberia, at the same time replacing a large proportion of the metal structure by less strategically critical wood. IL-4s also entered service with Soviet Naval Aviation, and it was a naval- manned force of these bombers that first raided Berlin from the east on 8 August 1941. Thereafter the IL-4 paid frequent visits to the German capital and other targets in Eastern Europe. In 1944 production ended, although the IL-4 served until the end of the war and afterwards. Apart from increasing the calibre of its guns and giving it a torpedo-carrying ability, the IL-4 remained virtually unchanged between 1941 and 1944.
Design and development
The Il-4 started life as a quickly produced bomber prototype called the TsKB-26. Parts of the fuselage and cockpit were taken from the TsKB-12 (Polikarpov I-16) fighter, married to new wings made of welded steel U-beams and tubes. Only a few were built before attention turned to the updated TsKB-30, which included a new fuselage using the same construction methods. Welding the beams required three welds per joint, so the plane took a huge amount of time to build. Nevertheless the design had excellent range and was quite sturdy. It was put into production in 1936 as the DB-3, 1,528 being completed by 1939.
DB-3 was followed by the updated DB-3M, which looked similar with the exception of a much larger and more rounded nose. However the plane was actually quite different internally. Using lessons learned from the Li-2 (Douglas DC-3) the entire plane was re-built using T shaped formers instead of the tubes and U-beams. This led to a tremendous reduction in the time needed to build the plane, and the DB-3M was hurriedly put into production.
DB-3F / Il-4
A change of engine from the 950 horsepower (708 kW) M-87B to the 1,100 hp (820 kW) M-88 resulted in the DB-3F, which were eventually renamed in 1942 as the Il-4. Some series had wooden outer wings and front fuselage to conserve metals, and throughout the production engines and fuel tanks were upgraded for more performance while keeping the same range. However the most notable change was the addition of larger defensive guns in the turret, using the 12.7 mm UBT in place of the earlier 7.62 mm weapons. In addition it was found that the gunners were attacked first, so blocks of armor were placed around the gunner positions.
All this extra weight wasn't offset by the newer engines however, and the Il-4 proved to be slower than the earlier versions at only 404 km/h. An attempt to improve performance was made as the Il-6, adding large diesel engines and heavier armament. The engine proved unreliable and production was never started. The Il-4 remained in production until 1944, when just over 5,200 had been built.
Although the Il-4 was only a medium bomber, it had the range to be used on strategic missions. The VVS wasn't terribly interested in this role, but nevertheless the Il-4 was used on several highly publicized raids against Berlin. Most would be used on much shorter range missions, often adding another 1,000 kg of bombs under the wings, in addition to the internal 2,500 kg.
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 Bryansk, Russia 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, February 23 1945.
China: Chinese Nationalist Air Force 24 aircraft
* Crew: Four (pilot, navigator, gunner/wireless-operator, rear gunner)
* Maximum speed: 430 km/h (232 knots, 267 mph)
* 2 ? 7.62 mm ShKAS machine guns
* 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. ISBN 1-85780-084-2.
Web Reference: http://en.wikipedia.org/wiki/Ilyushin_Il-4
Ilyushin IL 4 history and specifications
This webpage was updated 30th August 2012
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