Preparation for Nagasaki Atomic Bomb by bombing experiment for Pumpkin type

   At Wendover Air Force Base, "Fat Man" type for endogenous test bombs had been produced. It was a Pumpkin type on 454kg with TNT. For the experiment of the simulated atomic bomb, USA Air Force exploded it by dropping indiscriminately on Osaka City on July 26, Shimada City on July 26th, Haya City on July 29 and so on. After that, "Fat Man" type was experimented using the test bullet F13 on Tinian airport on August 1, 1945. USA Air Force confirmed the function and operation of the test bomb. Further refurbished test bullet F18 was experimented and loaded on B - 29 on August 5, and carried out a dropping test. Until August 9, the F - 31, which was become the Nagasaki Atomic Bomb on August 9, the final experiment entered the completion phase on August 8.