The FREEWING Freebird Mk5 is a specialized two-seat experimental aircraft developed by the Freewing Aerial Robotics Corporation (also known as Freewing Flight Technologies) based in College Park, Maryland. The aircraft is most notable for its 'freewing' or controlwing design, which allows the wing to pivot in pitch relative to the fuselage. This configuration was engineered to maintain a constant angle of attack, thereby reducing vertical gust sensitivity by a claimed ratio of up to 4:1, while providing inherent resistance to spins and stalls. The design drew heavily from the historical work of George G. Spratt and George A. Spratt, who developed similar Controlwing concepts starting in the early 20th century.
Development of the Freebird series progressed through several iterations, with the Mk1 appearing between 1983 and 1985, followed by the Mk2 in 1989, the Mk3 in 1990, and the Mk4 in 1991. The Freebird Mk5 was specifically developed between 1992 and 1993. Hugh Schmittle, the company's president and CEO, served as the primary inventor and held patents for the lockable free wing and thrust-vectoring elements. Aerodynamic contributions for the preceding Mk4 were provided by John Roncz, a renowned aerodynamicist. By May 1993, the FAA had cleared a Mk5 prototype for flight testing. At that time, the company announced plans to offer the aircraft as a kit for $25,000 or as a fully assembled aircraft for $40,000.
Technically, the Freebird Mk5 is a single-engine piston landplane with a maximum takeoff weight (MTOW) of 500 kg and a wingspan of 10 meters. It features a fuel capacity of 42 liters, providing a maximum range of 120 nautical miles. Performance specifications include an optimum speed of 60 knots, a maximum climb rate of 700 feet per minute, and an absolute ceiling of 10,000 feet. Its STOL capabilities are reflected in a takeoff distance of 120 meters and a landing distance of 180 meters. While the specific engine model for the manned variant is undocumented, the company's related Scorpion UAV utilized a Rotax 447 engine.
Production was extremely limited, with no evidence of series factory manufacturing. One verifiable example, N315DC (serial FB-300), was registered to builder Christopher Flint and photographed in flight over the Golden Gate Bridge in April 2000. The Freewing Aerial Robotics Corporation also attempted to pivot the technology toward military applications, proposing the Scorpion reconnaissance UAV for the US Army and the French Navy. However, a funding collapse in April 2001 effectively ended the company's aviation manufacturing operations.