Known as "The Flying Crane," the Hughes XH-17 is one of the most interesting aircraft projects in history. The heavy-lift chopper was the first helicopter project taken on by the Culver City, California-headquartered Hughes Aircraft Company, run by the famed aviation Howard Hughes. It boasted a twin-bladed main rotor with a diameter of 134 feet, far larger than a conventional helicopter and almost double that of a conventional heavy-lifter.