Originally known by its design bureau designation of TsKB-26,[N 2] by which it was known at the time of its first flight in 1935, the type originally received the official designation of DB-3[N 3] by the time it entered production in early 1937.
An improved version, designed for ease of manufacture, was developed in 1938 as the DB-3F. The outer wing was redesigned with leading edge sweepback, for increased stability and control, while short field capability was improved by use of more efficient propellers and larger split level flaps. In reality, the Il-4 itself had no variants created, though it is commonly grouped together with the Ilyushin DB-3 to form a series as both are identical yet different aircraft.
The Il-4 had a service ceiling of 10,000 meters, comparable to several other bomber designs of the time. Its rate of climb was around 270 meters per minute. The airframe itself was remarkable tough, though it was not undefeatable. The main downside to the Il-4 was its limited defensive armament which while it may have been sufficient for early confrontations with German aircraft, quickly became outdated as the war progressed.
Following the conclusion of test flights in June 1939, the DB-3F was ordered into production, being redesignated Il-4 during 1940. Operation Barbarossa prompted transfer of the production lines to Siberia, with some examples having wood in place of certain metal components to conserve scarce metal stocks. Used for both long and short range missions, Il-4s of the Soviet navy were used for the USSR's first bombing raid against Berlin on the night of 8–9 August 1941. However, this required a lessened bombload to make it back, making shorter range attacks more preferable for the VVS. Other uses of the Il-4 included reconnaissance and transport roles. A total of 5,256 examples had been built when production finished in 1944. Though use of the Il-4 continued well into 1945 until the very end of the war. Also notably, several Il-4s were used against Soviet forces by Finnish personnel who managed to capture the aircraft.
- Crosby, Francis. The World Encyclopedia of Bombers.
Anness Publishing Ltd. (2013) ISBN 1 78019 205 3 Page 115
- Gunston, Bill. Illustrated Directory of Fighting Aircraft of World War II. Salamander Books. 1988. ISBN 0-86101-390-5 Page 404
- Crosby, Francis - World Bombers. Page 114