 The production types were designated B to C with only slight variations between each, and could be powered by the Hirth HM 500 A or B.The Bü 181 aircraft was a single-engine low-wing monoplane with fixed undercarriage, split flap, twin controls and two adjustable seats arranged side-by-side.The cabin section of the fuselage was of a tubular steel frame construction whereas the rear of the fuselage had a wooden shell.