Hunters Point Naval Shipyard cruiser USS Indianapolis Francis Birch Commander 509th Composite Group uranium-235 Tinian Project Alberta Little Boy
The Little Boy bomb, except for the uranium payload, was ready at the beginning of May 1945. There were two uranium-235 components, a hollow cylindrical projectile and a cylindrical target insert. The projectile was completed on 15 June, and the target insert on 24 July. The projectile and eight bomb pre-assemblies (partly assembled bombs without the powder charge and fissile components) left Hunters Point Naval Shipyard, California, on 16 July aboard the cruiser USS Indianapolis, and arrived on Tinian on 26 July. The target insert followed by air on 30 July, accompanied by Commander Francis Birch from Project Alberta. Responding to concerns expressed by the 509th Composite Group about the possibility of a B-29 crashing on takeoff, Birch had modified the Little Boy design to incorporate a removable breech plug that would permit the bomb to be armed in flight.
