On July 28, 1935, the plane that would become the B-17 "Flying Fortress" first took to the skies.
Immediately, the plane started breaking records.
An icon of World War II, the aircraft gained an ironclad reputation for both its staggering offensive output and its durability and resilience in the heat of battle.
"Without the B-17 we may have lost the war," the World War II general Carl Spaatz said.
Relive the legacy of this iconic American warplane from a prototype to its eventual enshrinement in military museums in the slides below.
The Boeing Model 299, later known as the B-17, was built as part of a United States Army Air Corps (precursor to the Air Force) competition to create a bomber that could fly faster than 200 mph with 2,000 pounds of bombs and a range of over 1,020 miles.
The development of the 299 was completely paid for by Boeing with no promise of reimbursement by the US government. The competition and the sunk costs represented a make-or-break trial for the young aircraft manufacturer.
Despite achieving a record-setting 2,100-mile flight from Seattle to Ohio, Boeing lost the competition after crashing the prototype because of a technical error.
As war brewed in Europe, however, the need for a long-range strategic bomber like the B-17 became apparent. In 1940, 20 B-17s were delivered to Britain's Royal Air Force. They were hastily deployed and performed poorly.
The tail of the aircraft was reinforced to sturdy the ride at high altitudes, and additional .50-caliber machine guns were added to turrets behind and below the aircraft to defend against fighter planes during bombing missions. The result was the B-17E, or the "Big Ass."
The B-17E was the first mass-produced model of the plane. It featured nine turret-mounted machine guns and could carry up to 4,000 pounds in bombs. Each newer version that came along would be more and more heavily armed.
The various versions of the B-17 flew with crews of about 10 airmen, who praised the plane for its ability to withstand heavy fire, sometimes completing missions even after losing engines. The unsung heroes of this operation were the ground crews and mechanics, who routinely made tattered B-17s safe again.
B-17s dropped 640,036 tons of bombs over Europe in daylight raids alone, mainly targeting Axis airfields and arms factories.
The name "Flying Fortress" refers to the many machine-gun turrets located along the sides, top, front, tail, and bottom of the aircraft, which helped defend the plane against enemy fighter planes.
Thanks to its many turrets, the B-17 was over twice as effective at downing enemy aircraft as similar bombers of the time. The famed 91st Bomb Group of the 8th Air Force alone shot down a confirmed 420 enemy planes, with another 238 probably destroyed and 127 damaged.
After World War II, the B-17 saw action in wars in Korea, Israel, and Vietnam.
Today fewer than 100 B-17 airframes exist. Toward the end of World War II the B-29 Superfortress began to take over, and later the B-52 emerged, but the B-17 remains an indelible symbol of the US war effort.
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