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Ultimate Gadget Freak Deciphers First Atomic Bombs

Ultimate Gadget Freak Deciphers First Atomic Bombs

In 1988, author Richard Rhodes received a Pulitzer Prize for "The Making of the Atomic Bomb" in which he described the previously top-secret inner workings of the bombs that were dropped on Hiroshima and Nagasaki in 1945.

He divulged â€” through his own personal research — what had been America's biggest secrets about the bombs, which were called Little Boy and Fat Man. In fact, Julius and Ethel Rosenberg were put to death on charges they had leaked atomic bomb secrets to Soviet agents.

But by his own admission, Rhodes has been topped by truck driver John Coster-Mullen of Waukesha, WI, who has built a highly accurate replica of the atomic bomb through an amazing piece of engineering research. His replica of a bomb casing is on display at the Wendover Airfield Museum in Utah. The precise inner workings of the bomb are disclosed in a self-printed book that Coster-Mullen sells on for $49.95.

Terry Sunday of El Paso, TX, says of Coster-Mullen's book, "Quite simply, there is NO better source of information on the technical details of the world's first two nuclear weapons ... Coster-Mullen describes the design, configuration, materials and assembly procedures of "Little Boy" and "Fat Man" to an unprecedented level of detail."

Some are shocked that Coster-Mullen would undertake such a task. Lawrence S. Wittner, a history professor, says, "The reality is that Coster-Mullen informs us about minutiae-the technical features of the original atomic bomb-rather than about far larger and more meaningful issues, such as why the Bomb was used, what it did to the people of Japan, and how its development and use triggered the nuclear arms race since 1945."

Wittner fails to understand that engineers take great interest in understanding how complicated machinery works, even if it is 64 years old and had been used for extremely destructive purposes. What's also interesting about Coster-Mullen is that he is not an engineer. In fact, he doesn't even have a college degree.

Coster-Mullen says he was originally inspired by a high school teacher who had worked on the Manhattan Project. He had hoped to study physics in college but was derailed into a 30-year career as a commercial photographer. After that he began driving trucks and, he says, "About 15 years ago I reintroduced myself to the (Manhattan) project, thinking I would build small replicas of the bombs." He and his son traveled to museums displaying bomb casings, taking measurements and photographs.

"Once the weapon casings were revealed to the public, anybody familiar with physics over the past few decades would be familiar with what the basic design features would be," says Coster-Mullen. "In the case of the Fat Man, it was an implosion design and for Little Boy it was what was called a gun-assembly weapon."

Coster-Mullen contacted officials at Los Alamos before Sept. 11, 2001, when they were much freer with the release of declassified documents. Then he interviewed original participants in the Manhattan Project. "I also had access to a lot of photographs," he says. "I started applying proportional measuring to these photographs, and I was able to derive specific dimensional information."

The beauty of Coster-Mullen's work is in the details. For example, he obtained a piece of a tungsten-carbide tamper used in test bombs from a Los Alamos engineer who had saved the piece as a memento. The tamper had a key role in the Little Man bomb and its exact dimensions were not publicly known.

The tamper was used as a neutron deflector, boosting the critical masses in the uranium core. Its density was also crucial in holding the core together to further boost the power of the explosion.

According to an article published in the New Yorker, the tamper fragment was half an inch wide, an inch long and two inches deep. Coster-Mullen got access to sophisticated industrial measuring equipment and determined the original diameter of the tungsten-carbide cylinder was 13.1513 inches. According to another source, the tamper cylinder weighed about 680 lbs.

"In some cases, one person would have saved one thing, and then I'd find out three years later that someone else had a piece of the very same object," says Coster-Mullen. "And then when interviewing people, they would fill in the blanks."

Bombs developed after Little Boy and Fat Man became far more sophisticated.

"The guys who worked on the first atomic bombs, particularly Little Boy, saw themselves as blacksmiths," says Coster-Mullen. "They constructed Little Boy literally with soldering guns, monkey wrenches and sledgehammers."

This cross section shows the major mechanical components, including a tungsten-carbide tamper, used in the Little Boy atomic bomb.
Cross-section drawing of the Y-1561 implosion sphere
This cross section shows the placement of the major components used in the implosion sphere of the atomic bomb called Fat Man.

Listen to a podcast with John Coster-Mullen:
John Coster-Mullen on the Engineering behind the First Atomic Bombs

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