In the 1980s, Jane's of London initiated an art project. It teamed great writers and a magician of light and shadow to profile famous WW II airplanes while telling combat episodes of their pilots. B-17: Roger Freeman, well known for his related works, discusses the distant cousin 247D civilian airliner, then XB-15 testbed, and next, the YB-17 service test units. On p. 10 is a foldout: one side is the 'Memphis Belle', a well used combat machine, turn it over to compare all three with their later cousin, B-29 Superfortress.
Early combat revealed defensive weakness in even the 'Flying Fortress', and it required more modifications- some just impracticable. Still, the Luftwaffe developed tactics to break up the prickly US formations. In the end, the best solutions were escort fighters around the bombers and low-level fighter-bombers to shoot up every airdrome.
Page 38 is another of those impressive cutaway drawings of the different bulkheads and equipment listed by number. P 42-44 is an outstanding drawing of the cockpit and bombardier stations-- any pilot will stop here and stare at the detailed panel. Soak it up guys- this is as close as most of us will ever get.
See: Flying Forts: The B-17 in World War II,B-17 Combat Missions