Ilyushin DB-3

https://en.wikipedia.org/wiki/Ilyushin_DB-3

The Ilyushin DB-3, where "DB" stands for Dalniy Bombardirovschik meaning
"long-range bomber", was a Soviet bomber aircraft of World War II. It was a
twin-engined, low-wing monoplane that first flew in 1935. It was the precursor
of the Ilyushin Il-4 (originally designated DB-3F). 1,528 were built.

The genesis of the DB-3 lay in the BB-2, Sergey Ilyushin's failed competitor to
the Tupolev SB. Ilyushin was able to salvage the work and time invested in the
BB-2's design by recasting it as a long-range bomber, again competing against a
Tupolev design, the DB-2, to meet the stringent requirements of an aircraft
capable of delivering a 1,000 kg (2,200 lb) bombload to a range of 3,000 km
(1,900 mi) at a maximum speed no less than 350 km/h (220 mph). He had redesigned
the BB-2 to take advantage of the radial Gnome-Rhône Mistral Major 14Kdrs
engine, for which the Soviets had purchased a license in 1934 as the M-85, and
had begun construction of the prototype of the BB-2 2K-14 as the TsKB-26 that
same year.

The TsKB-26 was more of a proof-of-concept vehicle to validate Ilyushin's ideas
on how to obtain long range than an actual bomber prototype. To speed the
construction process, it had a wooden fuselage and fin with metal wings and tail
surfaces. It made its first flight in the summer of 1935 and proved to be
stable, easily controllable and highly maneuverable; it performed the first loop
made by a twin-engined aircraft in the Soviet Union. It went on to set six world
records in its class, generally in payloads to height and speed over a 5,000 km
(3,100 mi) closed circuit.

The real prototype of the DB-3 was called the TsKB-30 and it was completed in
March 1936. It had a number of improvements over the TsKB-26, notably an
all-metal structure, an extended nose, an aft-sliding canopy with a fixed
windscreen and improved engine cowlings. It successfully passed the State
acceptance trials and was ordered into production in August 1936 as the DB-3,
although some sources refer to this initial series as the DB-3S for seriynyy
(series-built).

The DB-3 was not a simple or easy aircraft to manufacture as Ilyushin had pushed
the limits of the available construction technology to make it as light as
possible. For example, the spar in each wing panel had four parts which had to
be riveted together and there were numerous welds that each had to be inspected
by an X-ray machine, with many failures. In addition the internal riveting of
small-diameter tubing was also a difficult and time-consuming process.


Role
Bomber / torpedo-bomber

Manufacturer
Ilyushin

First flight
Summer 1935

Primary users
Soviet Air Forces (VVS)
Republic of China Air Force
Finnish Air Force

Produced
1936–1939

Number built
1,528

Variants
Ilyushin Il-4

In 1939, 30 DB-3s were supplied to the Republic of China Air Force during the
Second Sino-Japanese War and they saw heavy action against Japanese targets in
the Wuhan region from their bases in Sichuan (mostly used by the 8th Group),
before being replaced by B-24 Liberators in 1943.

Two DB-3s were responsible for shooting down the Finnish civilian Junkers Ju 52
passenger and transport plane Kaleva on June 14, 1940.

The Finns captured five force-landed DB-3Ms during the Winter War and during
1941 they purchased a further six DB-3Ms and four DB-3F/Il-4s from German
surplus stocks.

On the night of August 7-8, 1941, fifteen DB-3T torpedo bombers of the Baltic
Fleet dropped the first Soviet bombs on Berlin. From August 11, DB-3Fs of the
VVS resumed bombing.

Specifications (DB-3B, late production)

General characteristics
Crew: three
Length: 14.22 m (46 ft 8 in)
Wingspan: 21.44 m (70 ft 4 in)
Height: 4.19 m (13 ft 9 in)
Wing area: 65.6 m2 (706 sq ft)
Empty weight: 5,030 kg (11,089 lb)
Gross weight: 7,745 kg (17,075 lb)
Max takeoff weight: 9,450 kg (20,834 lb)
Powerplant: 2 × Nazarov M-87 9-cyl. air-cooled radial engines, 709 kW (951 hp)
each

Performance
Maximum speed: 439 km/h (273 mph, 237 kn)
Range: 3,800 km (2,400 mi, 2,100 nmi)
Service ceiling: 9,600 m (31,500 ft)
Rate of climb: 6.93 m/s (1,364 ft/min)
Wing loading: 118 kg/m2 (24 lb/sq ft)
Power/mass: 0.18 kW/kg (0.11 hp/lb)

Armament

3 × 7.62 mm ShKAS machine guns
1 × 20 mm ShVAK cannon (not always fitted)
Up to 2,500 kg (5,500 lb) of bombs




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