05/24/2026
For the 509th Composite Group, the unit given the responsibility of delivering the atomic bombs, security was a major concern right from the beginning. When Paul Tibbets was assigned to lead, he was given the choice of three air bases for the exclusive use of his project, and chose the one in Wendover, Utah. That December when the 509th was formally created, he made it very clear to the men that there would be no excuse for lapses in security, and throughout their existence made it clear that he meant it. The 509th included not only the plane crews, but the 309th Air Service Group, 603rd Air Engineering and 1027th Materiel Squadrons, 320th Troop Carrier Squadron, 1395th Military Company, and the 1st Ordnance Squadron. When they were in place on Tinian Island in the Pacific Theater, the group of scientists from Los Alamos, designated the 1st Technical Detachment, arrived to do final assembly of the bombs. This combination made them entirely self-sufficient, so there was little need for them to interact with other groups. On Tinian they were located in an isolated area, off-limits to others.
One of the essential aspects of this self-sufficiency was the ability of their maintenance crews to take care of anything the planes needed, from minor adjustments to engine replacements. No other maintenance crews needed to work on the planes or know about their classified modifications, which included reversible-pitch propellers, enlarged bomb bays, British single-point bomb releases, fuel injection, a weaponeer station, and minimal armor and armament.
Image Caption: The B-29 Superfortress Enola Gay lands at Tinian shortly after dropping the Little Boy atomic bomb on Hiroshima.
Image Credit: US Air Force
