The B-17 was called a Flying Fortress because of its fire power, not because of its ability to protect its crew. There was very little armor to do that. In most places the only thing between the crew and Mother Earth...sometimes more than four miles below...was a thin sheet of Alclad aluminum. As the aircraft strugged through acres of punishing flak, or was attacked by enemy fighters, there was no place to hide. Twenty-Seven-Eighty Blues is the personal memoir of a WWII ROBG (a Radio Operator Mechanic Gunner) who called this widely celebrated aircraft his Guardian Angel. ..".you had to practically blow her out of the sky to knock her down." he says. "Oh, the stories I could tell you about this once mighty aircraft."