Production. B-17 heavy bomber. Two of the four mighty engines of a new B-17F (Flying Fortress) bombers warm up at the airfield of Boeing's Seattle plant as another warship of the air awaits its flight test. The Flying Fortress has performed with great credit in the South Pacific, over Germany and elsewhere. It is a four-engine heavy bomber capable of flying at high altitudes. Sourced from the Library of Congress.
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