Tupolev Tu-4

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

Tupolev Tu-4
Class Aircraft
Type Bomber
Manufacturer Tupolev
Origin Russia (USSR)
Country Name Origin Year
Russia (USSR) 1947
Country Name Operational Year Retirement Year
Russia (USSR) 1949 1970 View
ManufacturerName Production From Production To Quantity
Tupolev 847 View

Toward the end of World War II, the Soviet Union saw the need for a strategic bombing capability similar to that of the United States Army Air Forces. The Soviet VVS air arm had the locally designed Petlyakov Pe-8 four-engined "heavy" in service at the start of the war, but only 93 had been built by the end of the war and the type was limited by having been equipped with unreliable turbocharged V12 diesel engines at the start of its service to give it longer range. The U.S. regularly conducted bombing raids on Japan, from distant Pacific forward bases using B-29 Superfortresses. Joseph Stalin ordered the development of a comparable bomber.

The U.S. twice refused to supply the Soviet Union with B-29s under Lend Lease. However, on four occasions during 1944, individual B-29s made emergency landings in Soviet territory and one crashed after the crew bailed out. 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 Soviet neutrality, America demanded the return of the bombers, but the Soviets refused. Three repairable B-29s were flown to Moscow and delivered to the Tupolev OKB. One B-29 was dismantled, the second was used for flight tests and training, and the third one was left as a standard for cross-reference. The aircraft included 1 Boeing-Wichita -5-BW, 2 Boeing-Wichita -15-BWs and the wreckage of 1 Boeing-Renton -1-BN – three different models from two different production lines. Only one of the 4 had de-icing boots as used on the Tu-4. With the Soviet declaration of war against Japan in accordance with the Yalta agreement to enter the war within 90 days of VE day (to allow it time to move its forces from Europe to Asia) at about 11pm on August 8, 1945—two days after the U.S. atomic bombing of Hiroshima and the subsequent entente with Japan ending, the fourth B-29 was returned to the US along with its crew.

Stalin told Tupolev to clone the Superfortress in as short a time as possible instead of continuing with his own comparable ANT-64. The reverse-engineering effort involved 900 factories and research institutes, who finished the design work during the first year; 105,000 drawings were made. By the end of the second year, the Soviet industry was to produce 20 copies of the aircraft ready for State acceptance trials.

The Soviet Union used the metric system, thus sheet aluminum in thicknesses matching the B-29's imperial measurements were unavailable. The corresponding metric-gauge metal was of different thicknesses. Alloys and other materials new to the Soviet Union had to be brought into production. Extensive re-engineering had to take place to compensate for the differences, and Soviet official strength margins had to be decreased to avoid further redesign, yet despite these challenges the prototype Tu-4 only weighed about 340 kg (750 lb) more than the B-29, a difference of less than 1%.

The engineers and suppliers of components were under pressure from Tupolev, Stalin, and the government to create an exact clone of the original B-29 to facilitate production and Tupolev had to overcome substantial resistance in favor of using equipment that was not only already in production but in some cases better than the American version. Each component made and each alteration was scrutinized and was subject to a lengthy bureaucratic process. Differences were limited to the engines, the defensive weapons, the radio (a later model used in lend-lease B-25s was used in place of the radio in the interned B-29s) and the identification friend or foe (IFF) system – the American IFF being unsuitable. The Soviet engine, the Shvetsov ASh-73 was a development of the Wright R-1820 but was not otherwise related to the B-29's Wright R-3350 — the ASh-73 also powered some of Aeroflot's remaining obsolescent Petlyakov Pe-8 airframes, an earlier Soviet four-engined heavy bomber whose production was curtailed by higher priority programs. The B-29's remote-controlled gun turrets were redesigned to accommodate the harder hitting and longer ranged Soviet Nudelman NS-23 23mm cannon. Kerber, Tupolev's deputy at the time, recalled in his memoirs that engineers needed authorization from a high-ranking general to use Soviet-made parachutes. Additional changes were made as a result of problems encountered during testing, related to engine and propeller failures and equipment changes were made throughout the aircraft's service life.

The Tu-4 first flew on 19 May 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 panic, since the Tu-4 possessed sufficient range to attack Chicago or Los Angeles on a one-way mission, and this may have informed the maneuvers and air combat practice conducted by US and British air forces in 1948 involving fleets of B-29s. Some attempts to develop midair refueling systems were made to extend the bomber's range, but these were fitted to only a few aircraft.

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, being replaced by more advanced aircraft including the Tupolev Tu-16 jet bomber (starting in 1954) and the Tupolev Tu-95 turboprop bomber (starting in 1956). By the beginning of the 1960s, the only Tu-4s still operated by the Soviets were used for transport or airborne laboratory purposes. A Tu-4A was the first Soviet aircraft to drop a nuclear weapon, the RDS-1.

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


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: 4 x 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: 10 x 23 mm Nudelman-Suranov NS-23 aircraft cannons, two each in four turrets and tail barbette
  • Bombs:
    • 6 x 1,000 kg (2,200 lb) bombs or
    • 1 x atomic bomb (Tu-4A) or
    • 2 x KS-1 standoff missiles (Tu-4K)

End notes