The "Flying Pancake", "Flying Flapjack", "Flying Saucer", and "Zimmer's Skimmer" were all names used to describe Charles H. Zimmerman's unorthodox V-173 and XF5U-1 aircraft. Two other descriptions: the world's fastest and slowest-flying airplane and the world's first vertical takeoff and landing airplane, might have been used to describe the XF5U1 that was built but never flown. Zimmerman's brainchild was designed to do just that, but was never given the chance....