Tupolev Tu-4

Tupolev Tu-4

Picture - Tupolev Tu-4 at Monino museum

Role: Strategic bomber
Manufacturer: Tupolev
First flight: 19 May 1947
Introduction: 1949
Retired: mid 1960s (Soviet Union)
Primary users: Soviet Air Force PLA Air Force
Produced: 1949-1952
Number built: 847
Developed from: B-29 Superfortress
Variants: Tupolev Tu-70 Tupolev Tu-75 Tupolev Tu-80 Tupolev Tu-85

The Tupolev Tu-4 (NATO reporting name: Bull) was a piston-engined Soviet strategic bomber that served the Soviet Air Force from the late 1940s to mid 1960s. It was a reverse-engineered copy of the U.S.-made Boeing B-29 Superfortress.

Design and development

Towards the end of World War II, the Soviet Union saw the need for a strategic bombing capability similar to that of the USAAF. The U.S. regularly conducted bombing raids on Japan, virtually in the Soviet Union's backyard, from distant Pacific forward bases using B-29 Superfortresses. Stalin ordered the development of a comparable bomber.

The U.S. refused to supply the Soviet Union with B-29 heavy bombers under Lend Lease, despite repeated Soviet requests. However, on three occasions during 1944, individual B-29s made emergency landings in Soviet territory after bombing raids on Japanese Manchuria and Japan. In accordance with the Soviet-Japanese Neutrality Pact, the Soviets were neutral in the Pacific War and the bombers were therefore interned and kept by the Soviets, despite American demands for their return. Stalin tasked Tupolev with cloning the Superfortress and Soviet industry was to produce 20 copies of the aircraft in just two years. The three B-29s were flown to Moscow and delivered into Tupolev OKB. One B-29 was fully dismantled, down to the smallest bolt, the second was used for flight tests and training, and the third one was left as a standard for cross-reference.

The Soviets used a different engine, the Shvetsov ASh-73, which had some parts in common with the Superfortress' Wright R-3350 but was not identical. The remote-controlled gun turrets were also redesigned to accommodate Soviet 23 mm cannons.

The Soviet Union used the metric system, thus 1/16th inch (1.6 mm) thick sheet aluminum and proper rivet lengths were unavailable. The corresponding metric-gauge metal was thicker; as a result, the Tu-4 weighed about 3,100 lb (1,400 kg) more than the B-29, with a corresponding decrease in range and payload.

Tu-4 engineers were under very heavy pressure to achieve an exact clone of the original B-29. Each minute alteration had to be scrutinized and was a subject to a lengthy bureaucratic process. For instance, because 1/16 inch nominal sheet thickness equals 1.5875mm, no industry in the USSR was willing to take the responsibility to produce sheets with such accuracy. Engineers had to lobby with high-ranking military officials even for the most basic common sense decisions. In another example, the Soviets reverse-engineered and copied the American IFF system and actually had it installed in the first Tu-4 built. As yet another example, Kerber, Tupolev's deputy at the time, recalled in his memoirs that engineers had to obtain an authorization from a high-ranking Air Force general in order to use Soviet-made parachutes for the crew.

The Tu-4 first flew on May 19th, 1947, piloted by test pilot Nikolai Rybko. Serial production started immediately, and the type entered large-scale service in 1949. Entry into service of the Tu-4 threw the USAF into a virtual panic, since the Tu-4 possessed sufficient range to attack Chicago, Los Angeles and New York City with a worthwhile load on a one-way mission, and this fear may have informed the maneuvers and air combat practice conducted by US and British air forces in 1948 involving fleets of B-29s. Some limited attempts to develop midair refueling systems were made to extend the bomber's range, but these were fitted to only a few aircraft.

Public display surprises the West

The aircraft was first displayed during a flyover at the Aviation Day parade on 3 August 1947 at the Tushino Airport in Moscow. Three aircraft flew overhead. It was assumed that these were merely the three B-29 bombers that were diverted to the USSR during World War II. Minutes later, what appeared to be a fourth B-29 aircraft appeared. Western analysts then concluded that the Soviets were capable of, and actually had, reverse engineered the B-29 because the Soviets were known to have only three B-29s. The appearance of an obvious Superfortress-derived Tu-70 transport over the crowd removed any doubt about the success of the reverse-engineering task.

People's Republic of China

In 1967, China attempted to develop its first Airborne Early Warning aircraft, based on the Tu-4 airframe outfitted with turboprop engines. The project was named KJ-1, with a Type 843 rotordome mounted on top of the aircraft. However, the radar and equipment was too heavy and the KJ-1 did not meet PLAAF's requirements, thus the project was cancelled in 1971.

Operational history

Eight hundred and forty-seven Tu-4s had been built when production ended in the Soviet Union in 1952, some going to China during the later 1950s. Many experimental variants were built and the valuable experience launched the Soviet strategic bomber program. Tu-4s were withdrawn in the 1960s, replaced by more advanced aircraft: the Tupolev Tu-95 (starting in 1956) and Tupolev Tu-16 (starting in 1954). By the beginning of the 1960s, the only Tu-4s still operated by the Soviets were used for transport or airborne laboratory purposes.

Variants

Tu-4 Main production version. Tu-4 AWACS Chinese prototype with KJ-1 AEWC, "AWACS" radar and powered by Ivchenko AI-20K turboprop engines. Tu-70 Airliner derivative, never reached mass production. Tu-75 Cargo aircraft derivative, never reached mass production. Tu-80 Bomber derivative, never reached mass production. Tu-85 Bomber derivative, never reached mass production.

Operators

Soviet Union

Soviet Air Force

The Soviet Air Force operated 847 Tupolev Tu-4 bombers between 1948 and early 1960. They were initially used as long range bombers. In 1954 the Soviets began phasing out the Tu-4; units upgraded to Tupolev Tu-16 bombers and, beginning in 1956, to Tupolev Tu-95 bombers. Tu-4s withdrawn from front line units were used for transport duties.

People's Republic of China

People's Liberation Army Air Force

A number of ex-Soviet Tu-4 aircraft were operated by PLAAF until the late 1960s. In 1967 China attempted to develop its first airborne early warning aircraft, based on the Tu-4 airframe. The project was named KJ-1 and mounted a Type 843 rotordome on top of the aircraft. However, the radar and equipment was too heavy, and the KJ-1 did not meet PLAAF's requirements. The project was canceled in 1971.

Survivors

Tu-4 4114 (c/n 286501), ex-KJ-1 AEWC, "4114" Stored at Datangshan, China Tu-4 4134 (c/n 2205008), "4134" Stored at Datangshan, China Tu-4 unknown (c/n 2805103), "01" Stored at the Central Air Force Museum, Monino, Russia

Specifications (Tu-4)

General characteristics

Crew: 11
Length: 30.18 m (99 ft)
Wingspan: 43.05 m (141 ft)
Height: 8.46 m (27 ft)
Wing area: 161.7 m� (1,743 ft�)
Empty weight: 35,270 kg (77,594 lb)
Loaded weight: 46,700 kg (102,950 lb)
Max takeoff weight: 65,000 kg (143,000 lb)
Powerplant: 4x� Shvetsov ASh-73TK radial engines, 1,790 kW (2,400 hp) each

Performance

Maximum speed: 558 km/h at 10,250 m (33,600 ft) (349 mph)
Range: 6,200 km (with 3,000 kg (6,600 lb) bomb load) (3,875 mi)
Service ceiling: 11,200 m (36,700 ft)
Rate of climb: m/s (ft/min)
Wing loading: 400 kg/m� (82 lb/ft�)
Power/mass: 0.11 kW/kg (0.07 hp/lb)

Armament

Guns: 10x� 23 mm Nudelman-Suranov NS-23 aircraft cannons, two each in four turrets and tail barbette
Bombs:

6x� 1,000 kg (2,205 lb) bombs or
1x� atomic bomb (Tu-4A) or
2x� KS-1 standoff missiles (Tu-4K)

Related development

B-29 Superfortress
Tupolev Tu-70
Tupolev Tu-75
Tupolev Tu-80
Tupolev Tu-85

Comparable aircraft

B-32 Dominator
Avro Lincoln
Messerschmitt Me 264

Bibliography

Bowers, Peter M. Boeing B-29 Superfortress. Stillwater, Minnesota: Voyageur Press, 1999. ISBN 0-933424-79-5.
Duffy, Paul and A. I. Kandalov. Tupolev: The Man and his Aircraft. Warrendale, Pennsylvania: SAE, 1996. ISBN 1-56091-899-3.
Gordon, Yefim and Vladimir Rigmant. Tupolev Tu-4: Soviet Superfortress. Hinckley, Leicestershire: Midland Counties Publications Ltd., 2002. ISBN 1-85780-142-3.
Hess, William N. Great American Bombers of WW II. St. Paul, Minnesota: Motorbooks International, 1999. ISBN 0-7603-0650-8.
Pace, Steve. Boeing B-29 Superfortress. Ramsbury, Marlborough, Wiltshire, UK: Crowood Press, 2003. ISBN 1-86126-581-6.
Rigmant, Vladimir. B-29, Tу-4 - стратегические близнецы - как это было (Авиация и космонавтика 17 (Крылья 4)) (in Russian). Moscow, Russia, 1996.

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Source: WikiPedia