B-17 Flying Fortress was a World War II heavy bomber. Its turbo-supercharged radial engines gave it the necessary high-altitude performance to fly above the effective range of antiaircraft artillery.

Seventy-five years after the B-17's first flight, an 88-year-old veteran sent the Boeing Company a letter. After explaining how he returned to England after a bombing raid over Germany with 179 flak holes in his airplane and only two out of the four engines working, he wrote: "I'm glad to be alive. Thank you for making such a good airplane."