How did three American B-29s become 850 Soviet Tu-4s?
Same plane, different name. They call it reverse engineering.
The Soviet Union confiscated one of the most advanced aircraft in America's World War II fleet, took it apart, then replicated it in just two years, historians say.
New details of how Soviet engineers copied the B-29 Superfortress and renamed it the Tu-4 bomber were released Thursday after a 12-year investigation by the Smithsonian Institution's National Air and Space Museum in cooperation with the Russian government and historians.
"The magnificent story of the Tu-4 has now come full circle," said George Larson of Air & Space/Smithsonian Magazine, which published the research in its February edition.
"It's a phenomenal feat of human engineering," museum curator and author Von Hardesty said at a panel discussion at the Russian Embassy. The new information was gathered from interviews as well as newly declassified documents, he said.
Revealing new details about a long-confounding Cold War mystery, the investigation tells what happened to three B-29s the Soviets never sent home after crews were forced to land on Soviet soil with engine problems or other emergencies in late 1944.
Allies at the time, the Soviets had asked for the B-29 under a U.S. lend-lease program, but Washington refused and sent them instead transports and other bombers. After the B-29s landed on Soviet soil, the crews were returned.
But Soviet leader Joseph Stalin ordered the bomber copied to give his military an aircraft far superior to what they had at the time, Hardesty said.
One of the confiscated planes was left untouched and used as a model and a second was used for test flights, said Maximilian Saukke, son of a Soviet engineer on the project.
The third, Saukke told Thursday's panel, was disassembled.
"The Tu-4 was a big surprise" when the West saw it flown at a 1947 Soviet air show, Hardesty said.
U.S. intelligence officials suspected soon thereafter that the Soviets seemingly had copied the B-29. The new research, though, details how the Soviets did it - through reverse engineering.
In part, it was done with strong management, a lot of hard work and the threat that failure could land workers in exile in Siberia.
Thousands eventually worked on the project - dubbed B-4 for bomber with four engines. And they did it 12 hours to 14 hours a day, seven days a week, at 900 factories and research institutes, researchers said.
They measured and photographed about 105,000 parts, and generated 40,000 detailed drawings of the confiscated plane.
"They took it apart component by component, panel by panel, almost rivet by rivet," Hardesty said in an interview.
"It was measured and copied and photographed, and then someone would get the assignment to replicate a part, like an altimeter."
He said they finished the design work in one year and produced planes in the second.
"Tupolev .. had radio links out to the various factories and they would report almost daily on their progress. It was the equivalent of their Manhattan project - high priority," Hardesty said, comparing the task to the U.S. effort to build the nuclear bomb.
On the cutting edge of technology at the time, the B-29 had a pressurized crew compartment, computerized defensive weapons system and advanced radar for bombing and navigation, Larson said.
The Soviet Union eventually built 850 Tu-4s. One dropped a nuclear test bomb in 1951 in territory that is now independent Kazakstan.
"The very existence of the Tu-4 and its jet-powered successors prompted the United States to set up an array of defensive systems, including the Nike surface-to-air missiles and the Skysweep radar-guided anti-aircraft guns of the 1950s," Hardesty writes.
Though Soviets made some adaptations to the B-29, they also copied some flaws.
Pressed into service while not fully developed, the B-29 was plagued by propeller problems and engine fires.
The engine was miserable, said retired Air Force Col. James L. Pattillo, a panel member who flew the bombers as a 24-year-old pilot. He said crews sometimes took spare engines on flights.
Soviet engineers eventually solved the engine overheating said, Vladimir Rigmant, director of the Tupolev Museum, an aeronautical museum named after designer Tupolev.
But at the outset, Rigmant said to laughter in the audience: "Our engines caught on fire as well as the American ones."
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