Vertical lift machine developed by J. Robertson Porter, exhibited at the Olympia Aero Show in March 1913. It consisted of a steel frame covered with a flexible skirt giving it a distinctive bell shape. Inside was a small rotor driven by a 50hp Gnome seven-cylinder air-cooled rotary engine mounted below, with the fifteen gallon and two gallon fuel and oil tanks revolving with the engine. A smaller parachute surface enclosed the pilot's station at the base. Horizontal control was achieved by manipulating sections of the skirt to release portions air pressure.