Tupolev Tu-4
The Tupolev Tu-4, NATO reporting name Bull, was a piston-engined Soviet strategic bomber reverse-engineered from Boeing B-29 Superfortresses interned in the Soviet Union in 1944. Built under Andrei Tupolev's bureau after Stalin cancelled his indigenous long-range bomber, it first flew on 19 May 1947 and gave the Soviet Union its first modern long-range bomber force, including the nuclear-capable Tu-4A that made the first Soviet airborne atomic bomb drop in 1951. Wikipedia puts production at 847 aircraft, ended in 1952. Replaced by the Tu-16 and Tu-95, it left Soviet service in the 1960s; China, given ten aircraft in 1953, flew the type until 1988 and converted examples into the KJ-1 early-warning prototype.
Why It Mattered
In 1945 the Soviet Union's air force was a formidable tactical arm, but it could muster only 32 serviceable four-engine bombers, the outdated Pe-8. Three Boeing B-29s that force-landed in the Soviet Far East in 1944 were interned and kept, and Stalin ordered the Tupolev bureau to copy the design exactly. The Tu-4 that resulted gave the Soviet Union an interim long-range bomber years sooner than an indigenous design could have done. In October 1951 a Tu-4 made the first Soviet airborne drop of an atomic bomb, near Semipalatinsk. Smithsonian Magazine judges that the programme also became the pathway for the rapid modernisation of the Soviet aviation industry. NATO assigned the type the code name Bull.
Design Notes
The Tu-4 was replicated more than designed. Tupolev's engineers took apart one interned B-29, the General H. H. Arnold Special, measuring and photographing some 105,000 parts and generating 40,000 drawings. A second B-29 was grounded to serve as a reference, and only the third, Ramp Tramp, kept flying. The programme rallied some 64 design bureaus and over 900 factories, institutes and other organisations. Soviet plants worked in metric gauges, so the aluminium skin varied between 0.8 and 1.8 millimetres; even so, the finished bomber weighed only one percent more than the B-29. The substitutions were concentrated where it mattered: Shvetsov ASh-73TK engines of 2,300 horsepower replaced the Wright R-3350, and NS-23 cannon replaced the .50-calibre machine guns. Even the B-29's Central Station Fire Control System, its computerised remote firing system, was reproduced successfully.
Operational History
The Tu-4 first flew on 19 May 1947, with Nikolai Rybko at the controls, less than two years after the programme was launched. That August, three Tu-4s and a Tu-70 passenger version flew past at the Aviation Day parade at Moscow's Tushino airfield. Western observers at first assumed the bombers were the interned B-29s, until the Tu-70 showed that the Soviets were flying freshly built copies. Early service brought teething troubles: engine overheating, runaway propellers, deicing failures and chronic landing-gear failures, all corrected in time. The type became truly operational in 1948 and 1949, and by 1950 Long Range Aviation had deployed nine regiments of 32 bombers each. Wikipedia puts the total built at 847 aircraft by the time production ended in 1952. About 32 aircraft were based in the Soviet Far East in the reconnaissance role. On 18 October 1951 a Tu-4 dropped an atomic bomb near Semipalatinsk, the first such airborne drop by a Soviet aircraft; the nuclear-capable variant was designated Tu-4A. The Soviets also experimented with the Tu-4 as a tanker, perfecting a probe-and-drogue refuelling system in October 1952. China received ten Tu-4s in February 1953, a transfer Smithsonian Magazine credits with giving the Chinese a credible bomber force for the first time. Wikipedia records the type's only combat mission in Chinese service in 1956, when two Tu-4s bombed Tibetan rebel positions in Sichuan. From 1954 the Tu-16 jet bomber began replacing it, followed by the Tu-95 from 1956, and Soviet Tu-4s were withdrawn during the 1960s.
Afterlife
By the beginning of the 1960s, the Tu-4s still in Soviet hands were used only for transport or airborne laboratory work. China kept the type far longer: eleven aircraft were refitted with AI-20K turboprop engines between 1970 and 1973, and the last PLAAF Tu-4 was retired only in 1988. China also produced its first airborne early warning aircraft from the airframe, the KJ-1, but its rotodome radar failed to meet requirements and the project was cancelled in 1979. Ramp Tramp, the B-29 whose internment started the programme, was scrapped in 1954 as the Tu-4 fleet itself was being dismantled. Few aircraft survive: Smithsonian Magazine records a lone Tu-4 standing on outdoor display at the Monino air museum outside Moscow. Wikipedia lists two more stored at Datangshan in China, among them the KJ-1 prototype, displayed at the museum north of Beijing.