North Field, Tinian Island, Mariana Archipelago.
Photographer: Manhattan Engineers.

Pulleys, levers, chains and human muscles combine to gently lift the fully assembled ‘Fat Man’ into a waiting trolley so as to transport it to the bomb bay of the B-29 Superfortress Bock’s Car. Some two days after its predecessor ‘Little Boy’ had razed Hiroshima to the ground – in a photo that was taken at the North Field Air Base on Tinian Island, possibly on the 8th of August 1945.

With Japan refusing to surrender in spite of the wide-scale death and destruction caused by the uranium ‘Little Boy’. Dropped over Hiroshima on the 6th of August 1945. Another atom bomb had become the need of the hour and the only one ready at the time was the plutonium enriched ‘Fat Man’. A 10,800 pounds egg-shaped bomb designed to implode at a predesignated moment over its target.

Size of the Fat Man Atomic Bomb.

Measuring 10 feet 8 inches in length with a diameter of 60 inches. ‘Fat Man’ had come packed with an explosive firepower equaling 21,000 tons of TNT. The plutonium for the bomb had been produced from uranium isotope 239. Processed in huge refineries in Hanford, Washington. A now decommissioned nuclear facility but then the heart that had fueled the Manhattan Project with tons of the rare metal for both experiments and weapons.

Unlike ‘Little Boy’ (see Farbound.Net Snippet: The Little Boy that killed 237,000 people). The ‘Fat Man’ had not required a projectile to start the atomic chain reaction. As an implosion device, it had a dense ring of 5,300 pounds of high-grade explosives stacked around a sub-critical plutonium core. Preset to explode at a configured time and crush the plutonium at the centre, to trigger the atomic chain reaction.

Released by the B-29 Superfortress Bomber Bock’s Car, on the 9th of August 1945 at about 10:58 a.m. ‘Fat Man’ had plummeted down to earth from a height of 30,000 feet and exploded after 43 seconds of free falling at an altitude of 1,650 feet above the ground. Although the bomb had missed its designated landmark in the industrial city of Nagasaki. Its blast is estimated to have killed between 40,000 to 70,000 people instantly and level half of its surface area.

While a more powerful weapon than ‘Little Boy’ and later discovered to have yielded a better fission (approximately 17%). The presence of hills and less inflammable objects on the ground had stemmed its enormous power and limited the destruction.

Inspiration behind the Atomic Bomb’s codename.

The bomb’s code name was inspired by Winston Churchill’s lumpish appearance, and like the ‘Little Boy’ which had replaced the earliest prototype ‘Thin Man’ as a gun-type fission weapon. The ‘Fat Man’ with its implosion design had succeeded the ‘Thin Man’ as a plutonium bomb. Developed under pressure to make up for the millions of dollars that were invested in harvesting plutonium.

Almost identical to the ‘Trinity Gadget’. Which had been used to conduct the world’s first atomic explosion in July 1945. The bomb had been initially scheduled to be dropped over the city of Kokura on the 11th of August 1945. Forecast of bad weather, however, had led the 509th Bomber Squadron, in charge of the mission, to advance the date to the 9th of August. Over Kokura, dense smoke and limited visibility had further prompted the crew to fly for the secondary target of Nagasaki.

The bomb that brought WW2 to an end.

Though more atomic bombs had been planned to be dropped over Japan in the coming days. Its surrender on the 14th of August 1945, made the ‘Fat Man’, the atomic bomb to bring Word War II to an end.

This photo which shows technicians of the ‘Project Alberta’ placing the bomb in the trolley is archived by the National Archives Catalog. Under a collection titled, Photographic Prints of Atomic Bomb preparation at Tinian Island 1945-1945. The original caption that accompanies the photo reads: FM (Fat Man) unit being placed on trailer cradle in front of Assembly Building #2.

A division of the Manhattan Project, the technicians of Project Alberta had comprised of military and civilian personnel. The division was tasked with the transportation and onsite assembly of the atomic bombs.