There's the famous story about the first flight of Boeing's 707. Boeing spent all their corporate money on developing the 707. They would have to go bankrupt if the 707 was not a success. The first flight was supposedly a knuckle busting event for fear that something would go wrong. The Boeing test pilot...barrel rolled the 707 on it's first flight! Actually, a barrel roll looks pretty spectacular and daring, but aerodynamically there's no stress to the airframe and from what I've read, it's not really that much of a risky maneuver. Bob Hoover, North American Aviation's premier test pilot would put a martini glass on the dashboard of his P-51 and do a barrel roll,and the level of the liquid in the Martini glass would be constantly level.