My favorite Jimmy Doolittle story is when Martin was developing the Marauder...B-26. It had lots of teething problems, and tended to kill a lot of young aircrew in accidents. So, being the old barnstormer that he was, Doolittle went up to the Martin plant in Baltimore and took a B-26 for a spin. Since it didn't have the 2 rudder yaw authority of the Mitchell, AND little stubby wings, AND big motors, it had bad asymmetric yaw qualities. Doolittle tells the other rider, "watch this"....and shut down one of the motors....and then does a full loop in that beast. He then developed the B-26 "NATOPS" syllabus, if you will.