Because it contained flying squadrons equipped with Boeing B-29 Superfortress bombers, C-47 Skytrain, and C-54 Skymaster transport aircraft, the group was designated as a "composite", rather than a "bombardment" formation.

[4] Because the organization developed by Tibbets was self-sustained, with flying squadrons of both Boeing B-29 Superfortress bombers and transport aircraft, the group was designated as a "composite" rather than a "bombardment" unit.

[9] Originally consisting of twenty-one crews, fifteen were selected to continue training,[10] and were organized into three flights of five crews, lettered A, B, and C.[11] The 393d Bombardment Squadron was commanded by Lieutenant Colonel Thomas J. Classen, who like Tibbets had combat experience in heavy bombers, commanding a Boeing B-17 Flying Fortress with the 11th Bombardment Group.

Initial training operations identified numerous other modifications necessary to the mission, particularly in reducing the overall weight of the airplane to offset the heavy loads it would be required to carry.

In January and February 1945, 10 of the 15 crews under the command of the Group S-3 (operations officer) were assigned temporary duty at Batista Field, San Antonio de los Baños, Cuba, where they trained in long-range over-water navigation.

The organization that was to become the 509th required its own transports for the movement of both personnel and materiel, resulting in creation of an ad hoc unit nicknamed "The Green Hornet Line".

The 603rd Air Engineering Squadron was unique in that it provided depot-level B-29 maintenance in the field, obviating the necessity of sending aircraft back to the United States for major repairs.

[22][8] With the addition of the 1st Ordnance Squadron to its roster, the 509th Composite Group had an authorized strength of 225 officers and 1,542 enlisted men, almost all of whom deployed to Tinian.

In addition to its authorized strength, the 509th had attached to it on Tinian 51 civilian and military personnel of Project Alberta, and two representatives from Washington, D.C.,[23] the deputy director of the Manhattan Project, Brigadier General Thomas Farrell, and Rear Admiral William R. Purnell of the Military Policy Committee.

En route to Tinian on 4 June 1945, the B-29 that became The Great Artiste made an intermediate stop at Mather Field, near Sacramento, California.

These "fly-away" aircraft were equipped with fuel-injected engines, Curtiss Electric reversible-pitch propellers, pneumatic actuators for rapid opening and closing of bomb bay doors and other improvements.

[31] The ground support echelon of the 509th Composite Group, consisting of 44 officers and 815 enlisted men commanded by Major George W. Westcott of the Headquarters Squadron,[32] received movement orders and moved by rail on 26 April 1945 to its port of embarkation at Seattle, Washington.

The Cape Victory made brief port calls at Honolulu and Eniwetok but the passengers were not permitted to leave the dock area.

[35] Project Alberta's "Destination Team" also sent most of its members to Tinian to supervise the assembly, loading, and dropping of the bombs under the administrative title of 1st Technical Services Detachment, Miscellaneous War Department Group.

The ground school indoctrinated combat crews in procedures regarding air-sea rescue, ditching and bailouts, survival, radar bombing, weather, wing and air force regulations, emergency procedures, camera operation, dinghy drills, and other topics related to combat operations.

[42] The official history of the Army Air Forces characterized the ridicule as "epitomized in a satirical verse entitled Nobody Knows, with a recurring refrain, 'For the 509th is winning the war.

'"[43] The group was assigned tail markings of a circle outline (denoting the 313th Wing) around an arrowhead pointing forward, but at the beginning of August its B-29s were repainted with the tail markings of other XXI Bomber Command groups as a security measure, because it was feared that Japanese survivors on Tinian were reporting the 509th's activities to Tokyo by clandestine radio.

During the month of July and the first eight days of August the thirteen bombers of the 393d Bombardment Squadron flew an intensive training and mission rehearsal program that consisted of: To accustom the Japanese to small groups of American bombers, training flights consisted of three planes that dropped a single bomb before returning to base.

For the uranium bomb code-named "Little Boy", fissile components consisted of a cylindrical target and nine washer-like rings that made up the hollow cylinder projectile.

The bomb's plutonium core (encased in its insertion capsule) and the beryllium-polonium initiator were transported from Kirtland to Tinian by C-54 in the custody of Project Alberta couriers.

Three Fat Man high explosive pre-assemblies designated F31, F32, and F33 were picked up at Kirtland on 28 July by three B-29s, two from the 509th and one from the 216th AAF Base Unit, and transported to North Field, arriving 2 August.

The six combat crews of the Hiroshima mission were briefed on their targets, operational flight data, and the effects of the bomb on 4 August 1945.

Trying in vain for 20 minutes to contact the control tower at Yontan Airfield to obtain landing clearance, Bockscar nearly ran out of fuel.

[n 1] After each atomic mission the group conducted other combat operations, making a series of pumpkin bomb attacks on 8 and 14 August.

Some Punkins (Crew B-7, Price) is believed to have dropped the last bombs by the Twentieth Air Force in World War II.

[73] After the announcement of the Japanese surrender, the 509th Composite Group flew three further training missions involving 31 sorties on 18, 20 and 22 August, then stood down from operations.

The group made a total of 210 operational sorties from 30 June to 22 August, aborted four additional flights, and had only a single aircraft fail to take off.

[76] The 509th Composite Group returned to the United States on 6 November 1945, and was stationed at Roswell Army Airfield, New Mexico.

[81] The training and operations of the 509th Composite Group were dramatized in a Hollywood film, Above and Beyond (1952), with Robert Taylor cast in the role of Tibbets.

[86] The story was retold in a partly fictionalized made-for-television film Enola Gay: The Men, the Mission, the Atomic Bomb (1980), with Patrick Duffy portraying Tibbets.