B-17 during the war

Below: a B-17G, the final production model which has 13 machine guns.

Below: a formation of B-17 under heavy flak (flak means Anti-Aircraft Guns)

Below: one of the many B-17s that are downed--this one with the whole wing blown off.

The "Memphis Belle" and its crew--the "Memphis Belle" was one of the first Fortresses to complete 25 missions, which means the crews can then retire.