Previously, on July 26, the bomb, along with ' Fat Man' was transported to Tinian Island by USS Indianapolis (CA-35) for final assembly. A U-235 projectile fired down a gun barrel collided with a stationary element, causing a mass increase leading to nuclear fission. Nuclear fission was achieved by the collision of two parts of active material (Uranium-235). The gun-type weapon possessed the power of 26,000,000 pounds of high explosives. The bomb weighed 9,000 pounds and had a diameter of only 28 inches. The bomb was dropped by a USAAF B-29 bomber, Enola Gay, piloted by U.S.
The atomic bomb used at Hiroshima, Japan, on August 6, 1945, was 'Little Boy'.
