** FILE ** The B-17F Memphis Belle is shown in the restoration hangar at the National Museum of the U.S. Air Force in Dayton, Ohio. The most celebrated American aircraft to emerge from World War II is undergoing a loving and fastidious restoration. (U.S. Air Force photograph via Associated Press)

** FILE ** The B-17F Memphis Belle is shown in the restoration hangar at the National Museum of the U.S. Air Force in Dayton, Ohio. The most celebrated American aircraft to emerge from World War II is undergoing a loving and fastidious restoration. (U.S. Air Force photograph via Associated Press)