Key point: China is not the only nation known for successfully reverse-engineering other countries' military equipment.

Few aircraft have as great a mark on history as the B-29, the pencil-shaped American four-engine bomber that dropped the atomic bombs over Hiroshima and Nagasaki.

What’s less well known is that the Soviet Union had its own B-29—as in, literally the same airplane, in all but a few respects. And like its American counterpart, this duplicate B-29 would deliver the Soviet Union’s first air-dropped nuclear weapon.

In World War I, Russia pioneered the use of heavy bombers when it successfully fielded enormous Sikorsky-designed Ilya Muromets four-engine biplanes against Kaiser Wilhelm’s Germany. The concept soon spread to all the major warring powers, and was elaborated into a doctrine of strategic bombing after the war. Strategic bombers are large aircraft that carry heavy bomb loads over great distances to hit strategic targets behind enemy lines such as factories, oil refineries, bridges and rail yards—or, as occurred frequently in World War I and II, urban population centers.

By World War II, however, the Soviet Air Force (the VVS) was largely a tactical air arm focused on hitting targets close to the frontline. The VVS only fielded ninety-three new four-engine Pe-8 strategic bomber during the war, while England and the United States deployed thousands of heavy bombers.

The United States’ most expensive weapons program during World War II was the development of the ultimate strategic bomber, the B-29 Superfortress. The B-29 exceeded its predecessors in speed, range and bomb load. It also featured remote-controlled defensive machine-gun turrets, while the eleven-man crew benefited from a fully pressurized crew compartment.

The new B-29s were deployed to the Pacific theater starting in 1944, where their great range allowed them to launch raids on the Japanese home islands—ultimately including the atomic bombings of Hiroshima and Nagasaki, as well as the even deadlier firebombing of Tokyo. The first units operated out of bases in southern China until the United States captured island bases closer to the Japan.

At the time, the Soviet Union was receiving aircraft from the United States through the Lend-Lease program, so Moscow twice requested that the United States send over B-29s. Washington declined.

However, between July and November 1944, the 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 embarking on raids against targets in Manchuria and Japan. A fourth B-29 crashed and was recovered.

Despite the U.S.-Soviet alliance during World War II, the Soviet Union was not (yet) at war with Japan, so the Soviet authorities seized the American aircraft—and refused requests that they be sent back! The crews were also interned for months before being released into neutral Iran.

Desiring a new strategic bomber as soon as possible, Stalin instructed the Tupolev design bureau to abandon its own design program and instead make an exact copy of the B-29. Which they proceeded to do—one screw at a time. One of the captured B-29s was completely dismantled in the process, while the other two were used for reference purposes and flight training.

A major difficulty for the massive plagiarizing effort was that the B-29 had been designed according to imperial units of measurement (yards, feet, inches, etc.) while the Soviet Union used the metric system—not only were extensive conversions necessary, but new gauges of sheet aluminum needed to be produced as well as many other entirely new components devised from scratch. The massive effort ended up involving sixty design bureaus and nine hundred different factories.

The resulting clone plane, dubbed the Tu-4, weighed only slightly more than the original B-29. It did have a few differences. Most notably, the Tu-4 used Russian 2,400-horsepower ASh-73TK radial engines instead of the original 2,200-horsepower Duplex Cyclone engines. Additionally, the B-29’s .50 caliber machine guns were replaced with much heavier twenty-three-millimeter cannons.

The Tu-4 was slightly slower than the B-29 with a maximum speed of 348 miles per hour, though the Russian plane boasted a higher service ceiling of thirty-six thousand feet to the thirty-one thousand of the B-29. Standard bomb load was also different: the B-29 could lug up to twenty thousand pounds of bombs, while the Tu-4 was intended to carry six 2,200-pound bombs. Most notably, the Tu-4 lacked the range of later model B-29s, and was a limited to an effective round-trip range of nine hundred miles when carrying a significant bomb load.

With the entry of the Soviet Union in the war against Japan, Stalin eventually returned one of the lost B-29s in 1945. Two years later, Western observers at the Aviation Day airshow at Tushino Air Base were startled to behold a formation of what appeared to be four B-29s flying overhead. NATO codenamed the aircraft the “Bull,” and had to hastily plan an air-defense strategy against the new strategic bomber threat.

The first Tu-4 regiments were activated in 1949, and two years later the type was making history: a specially modified Tu-4A was the first Soviet aircraft to drop an atomic bomb, the forty-two-kiloton RDS-3 Marya which fell on Semipalatinsk on October 18, 1951. The plutonium-uranium composite RDS-3 had twice the power of the first Soviet nuclear weapon, the RDS-1, which was a Fat Man–style plutonium-core bomb.

A total of 847 Tu-4s were built through 1952, and the type served as the mainstay of the Soviet Union’s strategic bomber force in the earliest years of the Cold War. However, the Tu-4 lacked the range to hit targets in the United States and return to base. A small number of the bombers were modified with in-flight refueling capability in an attempt to address this problem.

By the mid-1950s, the Tu-4 began to be replaced by the jet-powered Tu-16 Badger and the long-serving and longer-range Tu-95 Bear. The last Tu-4s were retired from Soviet service in the 1960s.

The sheer size of the Tu-4 meant it was suitable for testing out new technologies. Tu-4s were used as early test beds for aerial refueling technology, electronic warfare, and radiation reconnaissance. The Tu-4NM could air-launch LA-16 drones, and there were also Tu-4K maritime attack planes, which carried underwing KS-1 Komet radar-guided anti-shipping missiles with a range of over fifty miles. After passing up prototypes for an airliner and cargo plane (the Tu-70 and Tu-75, respectively), over three hundred Tu-4s were later converted into Tu-4D troop transports.

Stalin also gifted ten Tu-4s to China in 1953, which remained in service until 1988! The People’s Liberation Army Air Force even tried converting two to serve as its first AWACs aircraft, though the radar dish proved excessively bulky. Some of the Chinese Tu-4s can now be seen at the People’s Liberation Army Air Force Museum.

Ultimately, the B-29 proved an adaptable platform in both American and Soviet service. The Soviet experience also proved, yet again, that few technological gaps are so great that they can’t be bridged by a little reverse engineering among friends.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring. This article first appeared in 2016.

Image: Wikipedia.