The Ilyushin Il-4 (also known as the DB-3F) is a Soviet medium bomber used by the Soviet Air Force during the entire "Great Patriotic War". It was the most numerous Soviet conventional bomber for most of the war. Its NATO reporting name was Bob.
In 1938 the flawed DB-3 was redesigned. The aircraft's nose was extended and made more streamlined, the fuel tanks were enlarged, the wing structure was upgraded, and steel construction was replaced with duraluminium. The aircraft made its first flight on 21 May 1939, flown by Vladimir Kokkinaki. Production began in January 1940 and the original 949 hp (708 kW) Tumansky M-87B engines were replaced with 1,100 hp (820 kW) Tumansky M-88s in early 1940. The aircraft was initially known as the DB-3F, but was renamed as the Il-4 in March 1942.
Il-4s were widely used in tactical bombing missions by the Soviet Air Force from 1941 to 1945. The Il-4 had great range adequate for strategic missions, but this ability was rarely utilized due to the Air Force's doctrine. The Il-4 was, however, used for some strategic attacks, such as the bombings of Berlin in 1941 and Helsinki in 1944. Although the 7.62mm dorsal machine gun was replaced with a 12.7mm gun and more armour was added, the Il-4 was considered to be underarmed and vulnerable to the end. They were sometimes mistaken for Heinkel He 111s, causing friendly fire incidents. The Il-4 was retired from military service in 1947, and some examples were then used for aerial photography.
The Luftwaffe captured some Il-4s, of which four were sold to the Finnish Air Force. One was destroyed en route to Finland. The Il-4s were ironically used against Germans in the Lapland War in 1944-1945 and retired soon after the war ended. The code letters of the Il-4 were DF, referring to the original DB-3F designation.
- Crew: 4
- Length: 14.76 m (48 ft 5 in)
- Wingspan: 21.44 m (70 ft 4 in)
- Wing area: 66.70 m2 (718.0 sq ft)
- Empty weight: 5,800 kg (12,787 lb)
- Maximum takeoff weight: 12,120 kg (26,720 lb)
- Powerplant: 2 × Tumansky M-88B 14-cyl. air-cooled radial piston engines, 1,100 hp (820 kW)
- Maximum speed: 410 km/h (250 mph, 220 kn) at 6,500 m (21,325 ft)
- Range: 3,800 km (2,400 mi, 2,100 nmi) (max internal fuel), 2,600 km (1,404 nmi; 1,616 mi) with 1,000 kg (2,200 lb) bombs
- Service ceiling: 8,700 m (28,500 ft)
- Time to altitude: 13.6 min to 5,000 m (16,404 ft)
- Armament: 2 × 7.62×54mmR ShKAS machine guns in the nose and ventral hatch, 1 × 12.7×108mm UBT machine gun in the turret, bomb load of up to 2,500 kg (5,500 lb).