High Quality Content by WIKIPEDIA articles! The Waco C series were the firm`s first successful cabin biplane design, and was based on the F series airframe. The Model C series had a raised centre and rear fuselage to form a four-seat cabin which was entered through a door over the lower wing and had a rather ugly framed rear-view window dispensed with in the later standard cabins. The initial QDC model of 1931 had a 165 hp (123 kW) Continental A70 cowled engine and was fitted with a triangulated shock-cord tailwheel undercarriage.