The B-17E, the first mass-produced model Flying Fortress, carried nine machine guns and a 4,000-pound bomb load. It was several tons heavier than the prototypes and bristled with armament. The B-17E was the first Boeing airplane with the distinctive and enormous tail for improved control and stability during high-altitude bombing. The B-17 was a versatile aircraft performing bomber, search & rescue, reconnaissance, supply, transport, research, and unmanned drone missions throughout every theater of World War II.