The first sport single-seater of note in the early 1920s was the Lincoln "Sport," which was a biplane originall developed as a homebuilt by S.S. Swanson in 1923. It was put into limited production by the Lincoln Aircraft Co., of Lincoln, Nebraska, when Swanson became chief engineer there. The production model died for lack of a market because there were still plenty of cheap World War 1 surplus single seaters around for the sporting types. The Lincoln design was perpetuated as a homebuilt, however, when the plans were published in Modern Mechanics magazine in the early 1930s.
Capable of 100 mph and fully aerobatic.
Engine: Bristol Cherub III.
Max speed: 100 mph.