On a June day in 1945, Muscovites watched a giant four-engined bomber bank over a restricted airfield in the city’s northeast. Red stars marked the wings, but sharp eyes could still read two English words on the nose: “Ramp Tramp.” It was a Boeing B-29 Superfortress, one of three interned by the Soviets after emergency landings in the Far East, and Joseph Stalin wanted it copied. Exactly.

Twice the United States had refused to hand over B-29s under Lend-Lease. Now fate had delivered three of them into Soviet hands, and Stalin gave Andrei Tupolev an order that was as simple as it was ruthless: duplicate the Superfortress, down to the last rivet, in as short a time as possible. The result was the Tupolev Tu-4 — and when the West finally saw it, the reaction bordered on panic.

What followed was one of the most staggering feats of industrial reverse-engineering in history: 105,000 parts measured and cloned, 900-plus factories mobilised, and a finished bomber that weighed barely one percent more than the original.

Three B-29s and a “gift from God”

By the spring of 1945 the Soviet air force had grown into the most lethal tactical air arm of the war, with as many as 15,000 aircraft. Yet strategically it was almost naked — perhaps 32 serviceable four-engined bombers, all of them the outdated Petlyakov Pe-8. When three B-29s came down on Soviet soil in 1944 after raids on Japan, they were interned under the Soviet-Japanese Neutrality Pact and never returned.

Three repairable Superfortresses were flown to Moscow and handed to the Tupolev design bureau. One was carefully dismantled, one was kept flying as a reference, and one was preserved untouched as a master pattern. Stalin cancelled Tupolev’s own promising long-range design, the Samolet 64, to force the copy through. Tupolev, jailed by Stalin only years earlier, accepted the assignment reluctantly. He had no choice.

Cloning the impossible

The devil lived in the units. American sheet aluminium was gauged in fractions of an inch; the USSR worked in millimetres, and no Soviet plant could roll metal to the B-29’s exact 1/16-inch skin. Rather than lose months converting everything, Tupolev varied the Tu-4’s skin thickness between 0.8 and 1.8 mm — a change that actually strengthened the structure in places. Engines, cannon, radios and the identification gear were swapped for Soviet equipment; almost everything else was faithfully reproduced.

The discipline was total. Tupolev even ordered a repair patch and the exact interior paint scheme copied, partly to satisfy the secret police that no one had disobeyed Stalin’s order. The effort analysed some 105,000 parts and generated around 40,000 drawings. Astonishingly, the prototype came out just 340 kg — under one percent — heavier than a genuine B-29.

The Tushino shock

The Tu-4 first flew on 19 May 1947 in the hands of test pilot Nikolai Rybko. The public reveal came that August at the Tushino Aviation Day flypast. Western attachés watched three big bombers roar overhead and shrugged — obviously the three long-lost interned B-29s. Then a fourth aircraft appeared, followed by a passenger derivative. The penny dropped: the Soviets had cloned the Superfortress and were building it in numbers.

Entry into service threw the US Air Force into alarm. The Tu-4 had the range to reach targets deep inside the United States on a one-way mission, and in 1949 a Tu-4A dropped a Soviet atomic bomb. It was never a true intercontinental weapon, but it did not need to be: it handed Moscow a credible strategic bomber years ahead of schedule and jump-started the entire Soviet heavy-bomber programme.

Twilight of the Bull

NATO christened the aircraft “Bull.” A total of 847 were built before Soviet production ended in 1952. From 1954 the type was steadily displaced by the jet Tu-16 and the turboprop Tu-95 — both, tellingly, Tupolev designs that grew out of the Tu-4 experience.

Ten Tu-4s were gifted to China in 1953, and it was there the type soldiered on longest, some re-engined with turboprops and one converted into China’s first airborne-early-warning testbed. The last Chinese Tu-4 was retired in 1988. A lone example still stands at the Monino museum outside Moscow — the ghost of the American bomber that founded Soviet strategic air power.

Sources: Wikipedia; Von Hardesty, “Made in the U.S.S.R.” (Air & Space/Smithsonian, 2001); Air & Space Forces Magazine; National Museum of the USAF; Gordon & Rigmant, “Tupolev Tu-4: Soviet Superfortress”.