Opening scene from "Fortress"

The Boeing B17 Flying Fortress is a fourengine heavy bomber developed in the 1930s for the United States Army Air Corps

In 1934 the U.S. Air Corps was looking for a bomber capable of reinforcing the air forces in Hawaii, Panama, and Alaska. The capabilities of large fourengine aircraft exceeded those of shorterranged, twinengine aircraft.

Requirements were for it to carry a "useful bombload" at an altitude of 10,000 ft for 10 hours with a top speed of at least 200 mph

The prototype flew from Seattle to Wright Field in nine hours and three minutes with an average cruising speed of 252 miles per hour.