Towards 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 U.S. regularly conducted bombing raids on Japan, virtually in the Soviet Union's backyard, from distant Pacific forward bases using B-29 Superfortresses. Joseph Stalin ordered the development of a comparable bomber.
The U.S. declined to supply the Soviet Union with B-29 heavy bombers under Lend Lease. However, on three occasions during 1944, individual B-29s made emergency landings in Soviet territory after bombing raids on Manchukuo 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 Nudelman NS-23 23mm cannon.
The Soviet Union used the metric system, thus 1/16 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 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 dismantled B-29 had a small flaw in one wing - a small rivet hole that was drilled mistakenly by an unknown Boeing engineer. Given Stalin's order for preciseness, all Tu-4's had this same hole drilled in the same location on the wing.
Another item that ended up going all the way to Stalin himself were the markings to be used on the Tu-4. As Stalin had directed an exact copy to be made, that would natually mean copying the U.S. markings, but Tupolew knew that Stalin and the NKVD could view that as disloyalty to the USSR. The placing of Soviet red stars could also be interpreted as a willful disobedience of Stalin's directive to have an exact copy of the B-29 made. In the end Tupolev went to Stalin and presented the dilemma as a joke. Stalin was reported to have laughed, then approved having Soviet markings applied to the Tu-4.
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 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.
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 m² (1,743 ft²)
- 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 × 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/m² (82 lb/ft²)
- Power/mass: 0.11 kW/kg (0.07 hp/lb)
Armament
- Guns: 10× 23 mm Nudelman-Suranov NS-23 aircraft cannons, two cannons in each of the four turrets, two cannons in the tail barbette
- Bombs:
- 6× 1,000 kg (2,205 lb) bombs or
- 1× atomic bomb (only Tu-4A) or
- 2× KS-1 Komet standoff missiles (only Tu-4K; these anti-ship missiles resembled a scaled-down MiG-15)
