17 August 1942: Mission No. 1. The United States VIII Bomber Command made its first heavy bomber attack on Nazi-occupied Europe when eighteen Boeing B-17E Flying Fortress four-engine bombers of the 97th Bombardment Group (Heavy), based at RAF Polebrook, Northamptonshire, England, headed for the railroad marshaling yards at Rouen-Sotteville, France. This was the largest and most active railroad yard in northern France.
The group began takeoffs at 1530 hours. It was escorted by several squadrons of Royal Air Force Supermarine Spitfire fighters.
While six B-17s flew along the French coast as a diversion, twelve bombers flew to Rouen and were over the target from 1739 to 1746. From an altitude of 23,000 feet (7,010 meters), they dropped 39,000 pounds (17,690 kilograms) of general purpose bombs.
Accuracy was good. One of the aim points, the locomotive shops, was destroyed by a direct hit. The overall results were moderate.
All of the bombers returned to their base, with the first landing at 1900. Two B-17s had been damaged. American gunners claimed damage to one Luftwaffe airplane.
The raid was commanded by Brigadier General Ira C. Eaker aboard Yankee Doodle, B-17E 41-9023, leading the second flight of six B-17s. The 97th Bombardment Group Commander, Colonel Frank A. Armstrong, Jr., flew as the co-pilot of the lead ship, Butcher Shop, B-17E 41-2578, with pilot Major Paul W. Tibbets, Jr. Major Tibbets was in command of the 97th’s 340th Bombardment Squadron. (He would later command the 509th Composite Group and fly the B-29 Superfortress Enola Gay.)
The Boeing B-17E Flying Fortress was a major redesign. A new aft fuselage was used, incorporating larger vertical and horizontal stabilizers. A tail turret was added. A power-operated gun turret was added at dorsal and ventral positions.
The Boeing B-17E Flying Fortress was a four-engine heavy bomber operated by a flight crew of ten. It was 73 feet, 10 inches (22.504 meters) long with a wingspan of 103 feet, 9-3/8 inches (31.633 meters) and an overall height of 19 feet, 2 inch (5.842 meters). Its empty weight was 32,350 pounds (14,674 kilograms), 40,260 pounds (18,262 kilograms) gross weight, and the maximum takeoff weight was 53,000 pounds (24,040 kilograms).
The B-17E was powered by four air-cooled, supercharged, 1,823.129-cubic-inch-displacement (29.875 liters) Wright Cyclone G666A (R-1820-65) nine-cylinder radial engines with turbochargers, producing 1,200 horsepower at 2,500 r.p.m. for takeoff and 1,000 horsepower at 2,300 r.p.m. at Sea Level. The Cyclones turned three-bladed constant-speed Hamilton-Standard Hydromatic propellers with a diameter of 11 feet, 7 inches (3.835 meters) though a 0.5625:1 gear reduction. The R-1820-65 was 47.59 inches (1.209 meters) long and 55.12 inches (1.400 meters) in diameter. It weighed 1,315 pounds (596 kilograms). 8,422 of these engines were produced by Wright Aeronautical Division and its licensees between February 1940 and August 1942.
The B-17E had a cruise speed of 195 miles per hour (314 kilometers per hour). Its maximum speed was 318 miles per hour (512 kilometers per hour) at 25,000 feet (7,620 meters). The service ceiling was 36,600 feet (11,156 meters).
With a normal fuel load of 2,490 gallons (9,426 liters) the B-17E had a maximum range of 3,300 miles (5,311 kilometers). Carrying a 4,000 pound (1,814 kilogram) bomb load, the range was 2,000 miles (3,219 kilometers).
The B-17E Flying Fortress was armed with one .30-caliber Browning M2 Aircraft Machine Gun and eight Browning AN-M2 .50-caliber machine guns. The .30 was mounted in the nose. Power turrets mounting two .50-caliber guns, each, were located at the dorsal and ventral positions. (The first 112 B-17Es were built with a remotely-operated turret in the belly position, sighted by a periscope. A manned ball turret replaced this.) Two machine guns were in a tail turret, and one on each side at the waist.
The maximum bomb load of the B-17E was 20,800 pounds (9,435 kilograms) over very short distances. Normally, 4,000–6,000 pounds (1,815–2,722 kilograms) were carried. The internal bomb bay could be loaded with a maximum of eight 1,000 pound (454 kilogram) or four 2,000 pound (907 kilogram) bombs.
The B-17 Flying Fortress first flew in 1935, and was in production from 1937 to 1945. 12,731 B-17s were built by Boeing. 512 of the total were B-17Es. The last one was completed 28 May 1942. Production shifted to the further-improved B-17F.
6 August 1945: At 0245 hours, a four-engine, long range heavy bomber of the 509th Composite Group, United States Army Air Forces, took off from North Field on the island of Tinian in the Northern Mariana Islands, on the most secret combat mission of World War II.
The Martin-Omaha B-29-45-MO Superfortress, 44-86292, under the command of Colonel Paul W. Tibbets, Jr., was carrying Bomb Unit L-11, the first nuclear weapon to be used during war. This was a 9,700-pound (4,400 kilogram) “gun type” fission bomb, the Mark I, code-named Little Boy. It contained 64 kilograms (141.1 pounds) of highly-enriched uranium. The bomb was 120 inches (3.048 meters) long with a diameter of 28 inches (0.711 meter). Although it was a very inefficient weapon, it was considered to be such reliable design that it had not been tested.
On the morning before the mission, Colonel Tibbets had his mother’s name painted on the nose of the airplane: Enola Gay. He had personally selected this bomber, serial number 44-86292, while it was still on the assembly line at the Glenn L. Martin Company plant at Bellevue, Nebraska, 9 May 1945. The B-29 was accepted by the Army Air Corps on 15 May and flown to the 509th’s base at Wendover, Utah, by Captain Robert A. Lewis, a B-29 aircraft commander who would act as Tibbets’ co-pilot on the atomic bombing mission.
The B-29 Superfortress was designed by the Boeing Airplane Company as its Model 345. Produced in three major version, the B-29, B-29A and B-29B, it was built by Boeing at Wichita, Kansas and Renton, Washington; by the Bell Aircraft Corporation at Marietta, Georgia; and the Glenn L. Martin Company at Fort Crook (now Offutt Air Force Base, Omaha, Nebraska. A total of 3,943 Superfortresses were built.
The B-29 was the most technologically advanced airplane built up to that time, and required an immense effort by American industry to produce.
The B-29 Superfortress was 99 feet, 0 inches (30.175 meters) long with a wingspan of 141 feet, 3 inches (43.053 meters) and an overall height of 27 feet, 9 inches (8.458 meters). The standard B-29 had an empty weight of 74,500 pounds (33,793 kilograms) and gross weight of 120,000 pounds (54.431 kilograms).
The Silverplate B-29s differed from the standard production bombers in many ways. They were approximately 6,000 pounds (2,722 kilograms) lighter. The bomber carried no armor. Additional fuel tanks were installed in the rear bomb bay. The bomb bay doors were operated by quick-acting pneumatic systems. The bomb release mechanism in the forward bomb bay was replaced by a single-point release as was used in special British Lancaster bombers. A weaponeer’s control station was added to the cockpit to monitor the special bomb systems.
Enola Gay had four air-cooled, supercharged, 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R-3350-41 (Cyclone 18 787C18BA3) two-row 18-cylinder radial engines with direct fuel injection. The R-3350-41 had a compression ratio of 6.85:1 and required 100/130 aviation gasoline. It was rated at 2,000 horsepower at 2,400 r.p.m. at Sea Level, and 2,200 horsepower at 2,800 r.p.m, for take-off. The engines drove four-bladed Curtiss Electric reversible-pitch propellers with a diameter of 16 feet, 8 inches (5.080 meters), through a 0.35:1 gear reduction. The R-3350-41 was 6 feet, 2.26 inches (1.937 meters) long, 4 feet, 7.78 inches (1.417 meters) in diameter and weighed 2,725 pounds (1,236 kilograms).
With the exception of the tail gunner’s position, all defensive armament—four powered remotely operated gun turrets with ten .50-caliber machine guns—were deleted. Their remote sighting positions were also removed. Enola Gay carried 1,000 rounds of ammunition for each of the two remaining Browning AN-M2 .50-caliber machine guns in the tail.
With these changes, the Silverplate B-29s could fly higher and faster than a standard B-29, and the new engines were more reliable. Enola Gay had a cruising speed of 220 miles per hour (354 kilometers per hour) and a maximum speed of 365 miles per hour (587 kilometers per hour). Its service ceiling was 31,850 feet (9,708 meters) and its combat radius was 2,900 miles (4,667 kilometers).
At 09:15:17 a.m., (mission time, 8:15 a.m., local), Enola Gay was at 31,000 feet (9,450 meters) over the Japanese city of Hiroshima on the island of Honshu, an industrial center with a population of about 340,000 people. The bombardier initiated the automatic release sequence and the the atomic bomb was dropped. It fell for 44.4 seconds and detonated at an altitude of 1,968 feet (600 meters), about 800 feet (244 meters) from the aiming point, the Aioi Bridge over the Ota River.
Ground Zero, the point on the surface directly below the explosion, was the Shima Hospital. The overpressure is estimated to have been 4.5–6.7 tons per square meter. The two-story brick building was completely obliterated. Of the patients, technicians, nurses and doctors inside, nothing remained.
The resulting explosion was approximately equivalent in explosive force to the detonation of 16,000 tons (14,515 metric tons) of TNT (16 “kilotons”). An estimated 70,000 people were killed immediately, and another 70,000 were wounded. As many as 160,000 people may have died as a result of the atomic bombing by the end of 1945. More would follow over the next few years.
An area of the city with a radius of 1 mile (1.6 kilometers) from the point of detonation (“hypocenter”) was totally destroyed, and combined with the fires that followed, 4.7 square miles (12.17 kilometers²) of the city were destroyed. 69% of all buildings in Hiroshima were completely destroyed and another 6% damaged.
As soon as the bomb was released, Colonel Tibbets turned his B-29 away to avoid the blast. It was just over 11 miles (17.7 kilometers) from the detonation point when the shock waves hit, but no damage resulted. The bomber was then flown back to Tinian, landing after an elapsed time of 12 hours, 13 minutes.
Enola Gay was placed in storage at Davis-Monthan Army Air Field, Tucson, Arizona, 26 July 1946, and was transferred to the Smithsonian Institution just over one month later, 30 August 1946. For decades it sat in storage at different locations around the country, but finally a total restoration was performed. Today, the B-29 is on display at the Steven F. Udvar-Hazy Center, National Air and Space Museum.