Ilyushin Il-4

Ilyushin Il-4

Company type	Aircraft
Industry	Aerospace, Military aviation
Founded	1939
Founder	Ilyushin design team
Headquarters	Soviet Union
Products	Long-range bomber and torpedo bomber aircraft

The Ilyushin Il-4 (DB-3F) (Russian: Ильюшин Ил-4 (ДБ-3Ф); known by NATO as Bob) was a Soviet twin-engine long-range bomber and torpedo bomber extensively deployed by both the Soviet Air Force and Soviet Naval Aviation throughout World War II.

Design and development

In 1938, the Ilyushin design team undertook a significant revision of the earlier Ilyushin DB-3, aiming to simplify manufacturing processes and enhance overall capabilities. This redesigned model was designated DB-3F (Forsirovanniye, meaning "boosted"). Major modifications were made to the aircraft’s internal framework, especially the wings, which were restructured to eliminate labor-intensive hand-finishing. Additionally, the widespread use of steel in the original was replaced by duralumin, reducing weight. A revamped fuel system increased internal fuel capacity while decreasing the number of tanks required. The nose section was extended to provide more space for the navigator/bombardier and to improve aerodynamic efficiency. The prototype DB-3F, powered by the same 949 hp (708 kW) Tumansky M-87B engines used on the DB-3M, made its first flight on 21 May 1939, piloted by Vladimir Kokkinaki. After successfully completing state acceptance trials, production commenced in January 1940. Soon after, the 1,100 hp (820 kW) Tumansky M-88 engines replaced the M-87s. In March 1942, the DB-3F was officially renamed Il-4.

To conserve strategic materials during production, some variants incorporated wooden outer wing panels and forward fuselage sections. Throughout its manufacturing run, engine models and fuel tanks were progressively upgraded to boost operational performance without sacrificing range. A significant enhancement involved upgrading defensive armament; larger caliber guns were installed in turrets, substituting earlier 7.62 mm (0.3 in) machine guns with more powerful 12.7 mm (0.5 in) UBT machine guns. Observations indicated that gunners were prime targets for enemy fire, prompting installation of armor plating around their positions.

Despite these improvements in firepower and protection, the additional weight was not fully compensated for by engine upgrades, resulting in a maximum speed reduction to approximately 404 km/h (251 mph), slower than previous models. Efforts to enhance performance led to development of the Ilyushin Il-6, which featured larger diesel engines and increased weaponry; however, due to engine reliability issues, this variant never entered production. The Il-4 continued to be manufactured until 1945, with total output exceeding 5,200 units.

Soviet Union

Though classified as a medium bomber, the Il-4 possessed sufficient range to undertake strategic bombing operations. The VVS did not prioritize this role, yet the Il-4 participated in several extended bombing sorties targeting Berlin during 1941. The majority of missions were conducted over shorter distances, frequently carrying an additional 1,000 kg (2,204 lb) of bombs mounted externally beneath the wings, supplementing the internal bomb load of 2,500 kg (5,512 lb)Template:Fix/category.

Finland

Finland acquired four DB-3Fs captured from German reserves. These aircraft were assigned Finnish Air Force serial numbers DF-22 through DF-25 and were flown from Bryansk, Russia to Finland; however, DF-22 was lost en route due to a crash near Syeschtschinskaya airfield. Subsequently, these planes saw service with No. 48 Sqn in 1943 (DF-23, DF-24, DF-25), No. 46 Sqn in 1944 (DF-23 and DF-24), and briefly with No. 45 Sqn in 1945 (DF-23). The final operational aircraft was retired to storage on 23 February 1945. Post-war, DF-25 was lost after landing on ice during a snowstorm and crashing into forested terrain near Öja, close to the city of Kokkola. Most components were recovered and stored in a depot.

Operators

File:Iljushin DB-3F (SA-kuva 148731).jpg

Ilyushin Il-4 serving with Finland; aircraft marked DF-25. Photo dated April 1944.

Template:China as ROC

• Chinese Nationalist Air Force operated 24 unitsTemplate:Fix/category

Template:FIN

• Finnish Air Force operated a total of eleven DB-3M models and four DB-3F (Il-4) aircraft

Germany

• Luftwaffe utilized for testing purposes only

Template:USSR

• Soviet Air Force

Active regiments during 1945–46 included:

10th Guards Bomber Aviation Regiment

290th Bomber Aviation Regiment

303rd Bomber Aviation Regiment (stationed at Zavitinsk, Amur Oblast)

442nd Bomber Aviation Regiment (based in Belogorsk, Amur Oblast) equipped with Il-4s

additional regiments also operated the type

• Soviet Naval Aviation

Specifications (Il-4)

File:Ilyushin Il-4 3-view line drawing.svg

Three-view schematic of Il-4 (1942)

See also

Bibliography

• "From DB-3 To Il-4...The Soviet Long-Range Bomber: Part Two". Air International, 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. ISBN 1-85780-084-2
• Gordon, Yefim, Dmitriy Komissarov and Sergey Komissarov. OKB Ilyushin: A History of the Design Bureau and its Aircraft. London: Ian Allan, 2004. ISBN 1-85780-187-3.
• Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey, 1995. ISBN 1-85532-405-9.
• Keskinen, Kalevi; Stenman, Kari and Niska, Klaus. Suomen Ilmavoimien Historia 9, Venäläiset Pommittajat (Soviet Bombers). Espoo, Finland: Tietoteos, 1982. ISBN 952-99432-7-X.
• Nowarra, Heinz J. and Duval, G.R. Russian Civil and Military Aircraft, 1884-1969. London: Fountain Press Ltd., 1971. ISBN 0-85242-460-4.
• Stapfer, Hans-Heiri. Ilyushin Il-4 in Action (aircraft number 192). Carrollton, Texas: Squadron/Signal Publications, Inc., 2004. ISBN 0-89747-471-6.