Fat Man and Little Boy Replicas

Little Boy was a gun-type bomb, meaning the weapon created a critical mass by shooting one piece of uranium into another. An earlier design, called Thin Man, used plutonium which is more powertul than uranium, but is both harder to produce and more volatile. Development of the gun-type proceeded utilizing uranium and resulted in Little Boy.

Fat Man was an implosion bomb, consisting of a plutonium core within a massive sphere of explosives. Upon detonation, the explosives crushed the softball-sized core to the size of a tennis ball, achieving critical mass. Though it was originally dismissed as overly complex, the implosion type proved to be the more successful design.

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