Vought XF5U

The Vought XF5U, nicknamed the Flying Flapjack, was an experimental fighter designed for the United States Navy by Charles H. Zimmerman and built by Vought during World War II. Its unorthodox airframe was a flat, roughly disc-shaped body that served as the lifting surface, with two piston engines buried inside it driving large propellers mounted at the wingtips. The XF5U-1 was a heavier, all-metal development of the earlier V-173 prototype, with a redesigned nose cockpit, a dorsal arrestor hook and an ejection seat so the pilot could clear the propellers in an emergency. The designers intended the propellers to counter the wingtip vortices that normally make a low aspect ratio wing inefficient, which would allow low takeoff and landing speeds alongside a high top speed. Only taxi trials and short hops were achieved, and the Navy canceled the program in March 1947 as jet aircraft arrived; the one completed prototype proved so sturdy that it had to be cut apart with torches.