The Boeing B-17E of 1941. The B-17E was the first "offensive" model of the Flying Fortress family. It first flew on September 5, 1941, and in the ensuing year many hundreds were produced at Boeing, Douglas and Lockheed. Among the major changes were a longer fuselage, increased fin area, dorsal and ventral power turrets, tail gun position and increased nose armament. Gross weight was increased to 60,000 pounds, and top speed to 325 mph. A total of 512 was built.