High Quality Content by WIKIPEDIA articles! The Waco S Series is a family of American cabin biplanes produced by the Waco Aircraft Company starting in 1935.The Waco closed cabin biplanes, initially known as the C (for Cabin) series were all unequal span, staggered single bay biplanes. They were fabric covered, the wings having a wooden structure and the control surfaces and fuselage constructed from metal frames. The wings were braced with outward splayed N form interplane struts plus a strut connecting the centre section rear spar to the bottom of the forward interplane strut, following Waco's standard practice. They had a fixed tailwheel undercarriage, which could be partially or completely faired. There was seating for 4/5 including the pilot. Most were powered by 7 cylinder radial engines of different makes.