History Takes Flight

With a collection of more than 200 historic aircraft, the EAA Aviation Museum is a year-round destination, combining aviation's past with the promise of its exciting future.

1938 Wittman Buttercup Model W - N18268

Location: Pioneer Airport

Steve Wittman designed and built Buttercup in 1938 and, over the years, it has featured a variety of innovations including - tapered rod landing gear, variable camber wings with full span leading edge and slotted trailing edge flaps.

The slats and flaps allow the pilot to change the shape of the wing to produce more lift at low speeds. They retract during normal flight for higher cruising speeds. This variable camber wing was quite futuristic and is used today on many high-performance, commercial and military aircraft.

This aircraft served as Steve Wittman’s test bed aircraft for light aircraft design for over 50 years.

Donated by the estate of Sylvester J. “Steve” and Paula M. Wittman, Oshkosh, Wisconsin.


20 ft. 3 in.


5 ft. 9 in.

Empty Weight

690 lbs.

Gross Weight

1,390 lbs.

Fuel Capacity

29 gal.


30 ft. 0 in.

Cruising Speed

123 mph

Maximum Speed

145 mph

Serial Number



85 hp., Continental C-85-12F, 188 cubic inch, 4-cylinder horizontally opposed

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