Tu-4 Bull

The Tupolev Tu-4 (NATO reporting name: Bull) is a Soviet four-engined, piston-powered strategic bomber developed by Tupolev. Reverse-engineered from seized American Boeing B-29 Superfortresses that made emergency landings in the Soviet Union during World War II, the aircraft entered Soviet Air Force service in 1949 as the USSR's first mass-produced long-range nuclear delivery platform.

Development

To establish a heavy strategic bombing capability to replace the obsolete Petlyakov Pe-8, Joseph Stalin ordered the direct copy of American Boeing B-29 Superfortresses interned during 1944. Tupolev was instructed to duplicate the B-29 rather than continue development of the native ANT-64/Tu-10. The reverse-engineering program involved 900 factories and research institutes, producing 105,000 engineering drawings. The prototype Tu-4 made its first flight on 19 May 1947, piloted by Nikolai Rybko, and serial production continued until 1952, yielding a total of 847 aircraft.

Design

Because Soviet industry utilized metric measurements, sheet aluminum gauges differed from standard U.S. measurements, requiring structural re-engineering that made the prototype 340 kg (750 lb) heavier than the original B-29 design. The aircraft was powered by four 1,790 kW (2,400 hp) Shvetsov ASh-73TK 18-cylinder air-cooled radial piston engines. Internal equipment modifications included radio equipment derived from Lend-Lease B-25 bombers, Soviet identification friend or foe (IFF) systems, and local parachutes. The aircraft retained the B-29 airframe dimensions, featuring a length of 30.18 meters, a wingspan of 43.05 meters, and a maximum takeoff weight between 55,600 kg and 63,600 kg.

Armament

Defensive armament consisted of ten 23 mm Nudelman NS-23 cannon mounted in pairs across four remote-controlled turrets and a manned tail barbette. Internal bomb bays carried a standard payload of six 1,000 kg high-explosive conventional bombs. Specialized nuclear variants were adapted to carry single RDS-1, RDS-3, or RDS-5 nuclear fission weapons, while anti-shipping configurations carried two underwing KS-1 Komet standoff anti-ship missiles.

Operational History

The Soviet Air Force introduced the Tu-4 into service in 1948, re-equipping the 185th Guards Aviation Regiment as its initial operational unit. A modified Tu-4A conducted the first Soviet air-dropped nuclear test when it released an RDS-3 bomb. The Soviet Union exported 12 Tu-4 airframes to the Chinese People's Liberation Army Air Force (PLAAF) between 1953 and 1960. Soviet front-line units phased out the type during the late 1950s as Tupolev Tu-16 jet bombers and Tu-95 turboprop bombers entered service, reassigning remaining airframes to transport and engine testbed roles. Chinese Tu-4s were retrofitted with Ivchenko AI-20K turboprop engines in the 1970s and remained in PLAAF service until 1988.

Variants

• Tu-4: Standard production strategic bomber variant equipped with Shvetsov ASh-73TK radial engines.

• Tu-4A: Modified nuclear-capable bomber variant configured to carry Soviet nuclear fission weapons.

• Tu-4D: Dedicated military troop transport conversion engineered to transport up to 300 personnel.

• Tu-4K: Anti-shipping strike variant modified with underwing pylons to launch two KS-1 Komet standoff missiles.

• KJ-1: Chinese airborne early warning prototype featuring AI-20K turboprop engines and a roof-mounted Type 843 radar rotodome.