During WWII, the United States helped USSR with military equipment such as Jeeps, tanks and 14000 airplanes through the Land Lease program and some of these aircraft were: Bell P-39 Aircobras, Bell P-63 Kingcobras, Curtiss P-40, Douglas A-20 Havocs and North American B-25s but the soviets wanted long-range bombers also. This request was declined by Washington twice, so they tried to build one instead.
The US deployed some B-29s in the Pacific theater starting in 1944, where their range allowed them to launch raids on the Japanese home islands, and in the end to drop the nuclear bomb on Hiroshima and Nagasaki. The intense fighting above Japan also meant higher chances of a B-29 being shut down by the enemies and this happened with 4 bombers between July and November 1944 when B-29s Ramp Tramp, Ding Hao, and General H. H. Arnold Special, operating out of China, were forced to land in Vladivostok due to battle damage or equipment failures while engaging targets in Manchuria and Japan. Another B-29 crashed but the Soviets recovered it.
Because the USSR was not officially at war with Japan, they seized all the B-29s that landed on their territory and refused to hand them over back to American authorities. After getting their hands on these aircraft they started to reverse engineer it to build their version and assigned this mission to the Tupolev design office. One of the B-29s captured was completely dismantled in the process, while the other two were used for reference purposes and flight training.
However, this was not the only method through which the USSR acquired American technology. During the 1930s, they sent students to the US to study and to infiltrate as spies in American factories and development centers. One of these students was Stanislav Shumovsky, codenamed Agent Bleriot. He got into the US in 1931 as an exchange student at MIT, where he also graduated, specializing in aeronautics and earning a master’s degree. He, along with other 64 Soviet students who had come to America, attended prestigious universities and visited or worked at Boeing, Douglas, California Technology Center (Caltech) or at NACA. Through this work, they were able later to get drawings of B-29 to Moscow and in the end help the Soviets to build the Tupolev T-4 codenamed by NATO “Bull”. He later worked at the USSR Embassy in the USA from where he tried to recruit American students as spies.
One problem of the Soviet engineers was that the Americans used the imperial measurement system (yards, feet, inches) while they used the metric system and that meant extensive conversions but also a re-engineering of the instruments panel and other components had to be built from scratch.
In the end, the airplane had more powerful weapons than the B-29 but it was a bit heavier due to the thickness of materials used. It also had more powerful engines at 2400 hp but flew at slower speeds and had a shorter range but a higher service ceiling.
When the Soviet Union entered the war against Japan, Stalin eventually returned one of the lost B-29s in 1945. In 1947, at the Aviation Day airshow at Tushino Air Base, western observers were amazed to see a formation of what appeared to be four B-29s flying above them. The first TU-4 regiments were activated in 1949 and two years later this was the Soviet plane that dropped an atomic bomb, the 42 kiloton RDS-3 Marya which fell on Semipalatinsk on October 18, 1951.
847 TU-4s were built from 1949 to 1952 and served as the main airplane of the USSR’s strategic bomber force in the earliest years of the Cold War, however, the Tu-4 lacked the range to hit targets in the US and return to base. A few bombers were modified to be capable of performing in-flight refueling in order to address this problem.
By the mid-1950s, the jet age had arrived, and the TU-4’s reign as the USSR’s primary bomber began to wane. Newer, jet-powered aircraft like the TU-16 “Badger” and the long-range TU-95 “Bear” took center stage. Despite its replacement, the TU-4’s legacy extended far beyond its combat service. The TU-4’s large size and rugged construction made it an ideal testbed for a variety of new technologies. It served as a valuable platform for developing and testing aerial refueling techniques, electronic warfare systems, and even radiation reconnaissance tools. Several specialized versions of the TU-4 were also developed. The TU-4K focused on maritime attack, carrying underwing anti-shipping missiles with impressive range. Additionally, over 300 TU-4s were converted into the TU-4D variant, designed to transport troops. Moreover, 10 bombers were gifted to China in 1953 and remained in service until 1988. China attempted to convert some of these TU-4s into the first of their Airborne Warning and Control System (AWACS) aircraft, but these modifications proved unsuccessful and they nowadays rest at the China Aviation Museum.