The Ellison-Mahon Gweduck is a contemporary American experimental amphibious aircraft designed to replicate the mission and aesthetic of the Grumman Widgeon using modern construction techniques. Developed by Ben Ellison and Bryan Mahon, the project began in 1990, with Ellison serving as the primary driver of the aircraft's development. The design process involved a team of engineers and craftsmen, resulting in a "hero-class" experimental amphibian that utilized advanced composite materials rather than traditional aluminum, marking a significant departure from the aircraft it was inspired by.
Production was centered at a facility in Prineville, Oregon. While the aircraft was intended for general sale via production kits, there is no evidence of a large-scale production run. Records indicate the completion of a prototype, and as of April 2017, the FAA registry confirmed at least one U.S.-registered example. By 2025, FAA records continued to list Ellison-Mahon Aircraft Inc. as the certificate holder for the Gweduck, specifically registration N204EM.
Technically, the Gweduck is a twin-engine piston aircraft. The standard powerplant consists of two Lycoming IO-540-M1B5 flat-six engines, each producing 300 hp. For those seeking higher performance, the manufacturer listed optional Lycoming TIO-540 J2B and LTIO-540 J2B engines capable of 350 hp each. The aircraft is configured to carry two pilots and four passengers. Its physical dimensions include a length of 34 ft 5 in, a height of 10 ft 6 in, and a wingspan of 48 ft 0 in when the floats are deployed. The wing area is 295.0 sq ft.
In terms of performance, the prototype has an empty weight of 4,200 lb and a maximum takeoff weight of 5,999 lb. It features a fuel capacity of 200 US gallons (167 Imperial gallons). At 3,000 ft and 65% power, the Gweduck achieves a cruise speed of 160 mph (130 kn). Although specific range figures are not provided, the design is noted for having better fuel economy and useful load than the original Grumman amphibians. The aircraft is strictly a civil experimental type with no documented military or wartime service.