Ram air was added for the carburetors, and modified several times to get even fuel pressure.

"Bonzo" featured a mid-winged taildragger design with a small squarish cross-section.

The aircraft was finished in red and silver, like Wittman's smaller racer "Chief Oshkosh".

The spinner featured a center cut-out to provide cooling air to a radiator.

[4] The D-12 "Bonzo" was donated by Wittman to anchor the EAA Airventure Museum in Oshkosh, Wisconsin in December 1959,[5] it was later restored for display in 1982.