Boeing's B-29 Superfortress was the most sophisticated, propeller-driven, bomber to fly during World War II, and the first bomber to house its crew in pressurized compartments. Boeing installed very advanced armament, propulsion, and avionics systems into the Superfortress. During the war in the Pacific Theater, the B-29 delivered the first nuclear weapons used in combat. On August 6, 1945, Colonel Paul W. Tibbets, Jr., in command of the Superfortress Enola Gay, dropped a highly enriched uranium, explosion-type, "gun-fired," atomic bomb on Hiroshima, Japan. Three days later, Major Charles W. Sweeney piloted the B-29 Bockscar and dropped a highly enriched plutonium, implosion-type atomic bomb on Nagasaki, Japan. Enola Gay flew as the advance weather reconnaissance aircraft that day. On August 14, 1945, the Japanese accepted Allied terms for unconditional surrender.
In the late 1930s, U.S. Army Air Corps leaders recognized the need for very long-range bombers that exceeded the performance of the B-17 Flying Fortress. Several years of preliminary studies paralleled a continuous fight against those who saw limited utility in developing such an expensive and unproven aircraft but the Air Corps issued a requirement for the new bomber in February 1940. It described an airplane that could carry a maximum bomb load of 909 kg (2,000 lb) at a speed of 644 kph (400 mph) a distance of at least 8,050 km (5,000 miles). Boeing, Consolidated, Douglas, and Lockheed responded with design proposals. The Army was impressed with the Boeing design and issued a contract for two flyable prototypes in September 1940. In April 1941, the Army issued another contract for 250 aircraft plus spare parts equivalent to another 25 bombers, eight months before Pearl Harbor and nearly a year-and-a-half before the first Superfortress would fly.
Among the design's innovations was a long, narrow, high-aspect ratio wing equipped with large Fowler-type flaps. This wing design allowed the B-29 to cruise at high speeds at high altitudes but maintained comfortable handling characteristics during slower airspeeds necessary during takeoff and landing. More revolutionary was the size and sophistication of the pressurized sections of the fuselage: the flight deck forward of the wing, the gunner's compartment aft of the wing, and the tail gunner's station. For the crew, flying at altitudes above 18,000 feet became much more comfortable as pressure and temperature could be regulated in the crew work areas. To protect the Superfortress, Boeing designed a remote-controlled, defensive weapons system. Engineers placed five gun turrets on the fuselage: a turret above and behind the cockpit that housed two .50 caliber machine guns (four guns in later versions), and another turret aft near the vertical tail equipped with two machine guns; plus two more turrets beneath the fuselage, each equipped with two .50 caliber guns. One of these turrets fired from behind the nose gear and the other hung further back near the tail. Another two .50 caliber machine guns and a 20-mm cannon (in early versions of the B-29) were fitted in the tail beneath the rudder. Gunners operated these turrets by remote control--a true innovation. They aimed the guns using computerized sights, and each gunner could take control of two or more turrets to concentrate firepower on a single target.
Boeing also equipped the B-29 with advanced radar equipment and avionics. Depending on the type of mission, a B-29 carried the AN/APQ-13 or AN/APQ-7 Eagle radar system to aid bombing and navigation. These systems were accurate enough to enable relatively accurate bombing through cloud layers that completely obscured the target. The B-29B was equipped with the AN/APG-15B airborne radar gun sighting system mounted in the tail to assist in providing accurate defense against enemy fighters attacking at night. B-29s also routinely carried as many as twenty different types of radios and navigation devices.
The first XB-29 took off at Boeing Field in Seattle on September 21, 1942. By the end of the year the second aircraft was ready for flight. Fourteen service-test YB-29s followed as production began to accelerate. Building this advanced bomber required massive logistics. Boeing built new B-29 plants at Renton, Washington, and Wichita, Kansas, while Bell built a new plant at Marietta, Georgia, and Martin built one in Omaha, Nebraska. Both Curtiss-Wright and the Dodge automobile company vastly expanded their manufacturing capacity to build the bomber's powerful and complex Curtiss-Wright R-3350 turbo supercharged engines. The program required thousands of sub-contractors but with extraordinary effort, it all came together, despite major teething problems. By April 1944, the first operational B-29s of the newly formed 20th Air Force began to touch down on dusty airfields in India. By May, 130 B-29s were operational. In June, 1944, less than two years after the initial flight of the XB-29, the U. S. Army Air Forces (AAF) flew its first B-29 combat mission against targets in Bangkok, Thailand. This mission (longest of the war to date) called for 100 B-29s but only 80 reached the target area. The AAF lost no aircraft to enemy action but bombing results were mediocre. The first bombing mission against the Japanese main islands since Lt. Col. "Jimmy" Doolittle's raid against Tokyo in April 1942, occurred on June 15, again with poor results. This was also the first mission launched from airbases in China.
With the fall of Saipan, Tinian, and Guam in the Mariana Islands chain in August 1944, the AAF acquired airbases that lay several hundred miles closer to mainland Japan. Late in 1944, the AAF moved the XXI Bomber Command, flying B-29s, to the Marianas and the unit began bombing Japan in December. However, they employed high-altitude, precision, bombing tactics that yielded poor results. The high altitude winds were so strong that bombing computers could not compensate and the weather was so poor that rarely was visual target acquisition possible at high altitudes. In March 1945, Major General Curtis E. LeMay ordered the group to abandon these tactics and strike instead at night, from low altitude, using incendiary bombs. These firebombing raids, carried out by hundreds of B-29s, devastated much of Japan's industrial and economic infrastructure. Yet Japan fought on. Late in 1944, AAF leaders selected the Martin assembly line to produce a squadron of B-29s codenamed SILVERPLATE. Martin modified these Superfortresses by removing all gun turrets except for the tail position, removing armor plate, installing Curtiss electric propellers, and modifying the bomb bay to accommodate either the "Fat Man" or "Little Boy" versions of the atomic bomb. The AAF assigned 15 Silverplate ships to the 509th Composite Group commanded by Colonel Paul Tibbets. As the Group Commander, Tibbets had no specific aircraft assigned to him as did the mission pilots. He was entitled to fly any aircraft at any time. He named the B-29 that he flew on 6 August Enola Gay after his mother. In the early morning hours, just prior to the August 6th mission, Tibbets had a young Army Air Forces maintenance man, Private Nelson Miller, paint the name just under the pilot's window.
Enola Gay is a model B-29-45-MO, serial number 44-86292. The AAF accepted this aircraft on June 14, 1945, from the Martin plant at Omaha (Located at what is today Offut AFB near Bellevue), Nebraska. After the war, Army Air Forces crews flew the airplane during the Operation Crossroads atomic test program in the Pacific, although it dropped no nuclear devices during these tests, and then delivered it to Davis-Monthan Army Airfield, Arizona, for storage. Later, the U. S. Air Force flew the bomber to Park Ridge, Illinois, then transferred it to the Smithsonian Institution on July 4, 1949. Although in Smithsonian custody, the aircraft remained stored at Pyote Air Force Base, Texas, between January 1952 and December 1953. The airplane's last flight ended on December 2 when the Enola Gay touched down at Andrews Air Force Base, Maryland. The bomber remained at Andrews in outdoor storage until August 1960. By then, concerned about the bomber deteriorating outdoors, the Smithsonian sent collections staff to disassemble the Superfortress and move it indoors to the Paul E. Garber Facility in Suitland, Maryland.
The staff at Garber began working to preserve and restore Enola Gay in December 1984. This was the largest restoration project ever undertaken at the National Air and Space Museum and the specialists anticipated the work would require from seven to nine years to complete. The project actually lasted nearly two decades and, when completed, had taken approximately 300,000 work-hours to complete. The B-29 is now displayed at the National Air and Space Museum, Steven F. Udvar-Hazy Center.
