It's an EAA Biplane. It is a homebuilt. Paul Poberezny designed the airplane and sold plans for it way back in the infancy of the EAA when the homebuilding movement was just getting started. The EAA Biplane was one the first original designs published by the Experimental Aircraft Association. A popular and successful design in its own right, the EAA Biplane was also the forerunner of EAA's popular Acro Sport series of aerobatic homebuilts.
In 1955, EAA founder Paul Poberezny was looking for a new design for a sporty-looking, open pit biplane for homebuilders. He turned to EAA member Jim D. Stewart to draw up plans for an easy-to-build biplane that would take advantage of up-to-date materials and methods. Stewart was at the time an aeronautical engineer at the Allison Engine Company in Indianapolis, IN. Allison built a wide variety of engines, including aircraft engines.
Stewart and three other Allison engineers agreed to design an airplane and draw a set of plans. Initially, they based their design on the Gere biplane, a popular 1930s-era homebuilt, but soon abandoned that route as impractical. Instead, they created an entirely new design. It used a welded-tube fuselage and wooden wing, with fabric covering, and was powered by a 65-horsepower Continental engine.
In its first test flights, in June of 1960, the airplane did not perform well, and it was returned to the school for modifications. These included a redesigned horizontal stabilizer and the addition of two degrees of incidence in the upper wing. Further test flights in November were much more successful and with a modified cowling (to improve engine cooling) and a new metal propeller, the airplane performed pretty much as its designers intended.
The EAA Biplane was then moved to EAA headquarters (then at Hales Corners, WI) for more modifications and testing. The bubble canopy was removed and replaced with a turtle deck, headrest, and windscreen, as in the original drawings. Poberezny and other EAA members suggested other changes to improve the appearance of the airplane, including a larger 85-horsepower engine, new instrument panel, smaller pit opening, redesigned engine and fuselage cowlings, and the addition of a propeller hub spinner. Several EAA members completed these modifications in time to unveil the completed prototype at the 1961 EAA convention at Rockford, IL. The plans for the EAA Biplane were updated and offered for sale, for $20, with profits dedicated to the "EAA Air Education Museum Building Fund."
EAA discontinued selling plans for this aircraft in 1972.