Production. B-17F heavy bombers. The brute force of a mighty plane engine, over a thousand horsepower, will strain at the bolt holes drilled by this girl worker in an engine bulkhead for a wing spar of a B-17F heavy bomber. She works in the Long Beach, California, plant of Douglas Aircraft Company. Better known as the "Flying Fortress," the B-17F is a later model of the B-17, which distinguished itself in action in the South Pacific, over Germany and elsewhere. It is a long range, high altitude, heavy bomber with a crew of seven to nine men and with armament sufficient to defend itself on daylight missions