While touring a B-17 with my youngest son at an air show a couple of years ago, when met and talked with an older gentlemen in the radio compartment for a few minutes. He was a tail gunner on a Fort in the 384th BG, and on the last mission he flew, his plane was struck by enemy fighters and blown in half. He was trapped in the tail section as it fell 25,000 ft and blacked out, but survived fall the relatively unharmed. They figured the lightness of the tail section combined with the large tail surfaces helped keep the falling speed low enough to avoid a fatal impact. Kinda like a leaf fluttering down from a tree. He spent the rest of the War as a POW.
Incredible stories.