The American Champion 8KCAB Decathlon and Super Decathlon are two-seat fixed conventional gear light airplanes designed for flight training and personal use and capable of sustaining aerobatic stresses between +6g and -5g. The Decathlon entered production in the United States in 1970 as a more powerful and stronger complement to the American Champion Citabria line of aircraft.
The Decathlon was designed by the Champion Aircraft Corporation, and is a derivative of the 7-series Citabrias. While the Citabria designs remain successful, and the introduction of the 7KCAB variant of the Citabria had added limited inverted flight capability, the Citabrias are not capable of "outside" maneuvers, those requiring significant negative-g loads. Pilots wanted an aircraft capable of more maneuvers, and Champion introduced the 8KCAB Decathlon in response to this demand.
The Decathlon traces its lineage back to the Aeronca Champ, by way of the Citabria. Like the Citabria, the Decathlon features tandem seating and center-stick controls. The fuselage and tail surfaces are constructed of welded metal tubing. The outer shape of the fuselage is created by a combination of wooden formers and longerons, covered with fabric. The cross-section of the metal fuselage truss is triangular, a design feature which can be traced back to the earliest Aeronca C-2 design of the late 1920s.
The strut-braced wings of the Decathlon are, like the fuselage and tail surfaces, fabric covered, using aluminum ribs. The wings of Champion and Bellanca Decathlons were built with wooden spars. American Champion has been using aluminum spars in the aircraft it has produced and has made the aluminum-spar wings available for retrofit installation on older aircraft. Compared to the Citabria’s wingspan of 33.5 feet (10.2 m), the Decathlon’s wingspan is shorter, at 32 feet (9.8 m). One of the major developments of the 8KCAB Decathlon over the 7KCAB Citabria is the Decathlon’s wing, which employs a semi-symmetrical airfoil, as opposed to the Citabria’s flat-bottomed airfoil. This change gives the Decathlon better inverted flight and negative-g maneuver capabilities.
The landing gear of the Decathlon is in a conventional arrangement. The main gear legs of most Decathlons are made of spring steel, though American Champion began to use aluminum gear legs in 2004.
Like the 7KCAB, the engine of the 8KCAB has a fuel injection system, as opposed to a carburetor. To facilitate negative-g flight, the fuel system incorporates a 1.5 gallon header tank beneath the instrument panel, and the engine is fitted with a Christen Industries inverted oil system.
Champion and Bellanca built the Decathlon with several Lycoming IO-320 engine variants, all of 150 horsepower (110 kW), and with the choice of a fixed-pitch or constant speed propeller. The major improvement in Bellanca’s introduction of the Super Decathlon was the change of engine to the Lycoming AEIO-360-H1A or –H1B, both of 180 horsepower (130 kW), which was accompanied by a selection of constant speed propellers. The American Champion Super Decathlon uses the AEIO-360-H1B, along with a constant speed propeller.