Little Boy

"'...Destroyer of the worlds'"

Background
The Little Boy device is a gun-type fission bomb. It is the cheapest but also potentially weakest nuclear device, it is also the only one that uses Uranium-235 for its destructive potential.

"Little Boy" was the codename for the first type of atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945, the second was the Fat man. During World War II. It was the first nuclear weapon used in warfare. The bomb was dropped by the Boeing B-29 Superfortress Enola Gay piloted by Colonel Paul W. Tibbets, Jr., commander of the 509th Composite Group of the United States Army Air Forces and Captain Robert A. Lewis. It exploded with an energy of approximately 15 kilotons of TNT (63 TJ) and caused widespread death and destruction throughout the city. The Hiroshima bombing was the second man-made nuclear explosion in history, after the Trinity test.

Little Boy was developed by Lieutenant Commander Francis Birch's group at the Manhattan Project's Los Alamos Laboratory during World War II, a reworking of their unsuccessful Thin Man nuclear bomb. Like Thin Man, it was a gun-type fission weapon, but it derived its explosive power from the nuclear fission of uranium-235, whereas Thin Man was based on fission of plutonium-239. Fission was accomplished by shooting a hollow cylinder of enriched uranium (the "bullet") onto a solid cylinder of the same material (the "target") by means of a charge of nitrocellulose propellant powder. It contained 64 kg (141 lb) of enriched uranium, although less than a kilogram underwent nuclear fission. Its components were fabricated at three different plants so that no one would have a copy of the complete design.

Bomb Itself

 * 2 Small Steel Shells
 * 1 Small Steel Grid Fin
 * 1 Military Grade Circuit Board (Tier 2)
 * 6 Aluminium Wires
 * 4 Blue Dye (Lapis Lazuli)

Neutron Shielding

 * 12 Neutron Reflectors 4 Steel Plates

Subcritical U235 Target

 * 7 U235 Nuggets

U235 Projectile

 * 3 U235 Nuggets

Propellant

 * 3 TNT
 * 8 Iron Plates
 * 4 Aluminium Plates
 * 4 Red Copper Wires

Bomb Igniter

 * 6 Aluminium Plates
 * 1 Steel Plate
 * 1 Advanced Circuit
 * 3 Red Copper Wires