The Vought V-173 "Flying Pancake" was an American experimental test aircraft built as part of the Vought XF5U program during World War II. Both the V-173 and the XF5U featured an unorthodox "all-wing" design consisting of a flat, somewhat disk-shaped body (like a pancake flying, hence the nickname) serving as the lifting surface. Two piston engines buried in the body drove propellers located on the leading edge, at the wingtips.