Had to look up Bob Hoover. Found a great YOUTUBE link with him narrating: http://www.youtube.com/watch?v=TUVWHUR5OEI
Quite an incredible clip. He demonstrates the maneuver and, with a cargo full of military generals, demonstrates rolling the craft while they gens are drinking coffee, and again while he himself pours iced tea into a glass - not a drop spilled - this with the engines OFF.
Yep.... when Hoover rolled the bird in front of the crowd with both props stopped, you could hear the soft “whoosh” of the silent plane cutting through the air, the crowd of 30,000+ was that quiet.