The C.IX was a
two-bay biplane design. The pilot's
cockpit was placed underneath the
trailing edge of the upper wing, with the
observer's cockpit behind his. The wing had a large semi-circular cutout above the cockpit to improve the pilot's visibility above the aircraft. The prototypes differed slightly from each other to compare
aileron and
tail surface configurations. One aircraft only had ailerons on the upper wing while another had ailerons on both wings; those on the lower wing were actuated by a strut connecting the ailerons together. To reduced airflow interference, the gap between the wings was maximized by suspending the
fuselage above the lower wing with several small
struts. The C.IX was powered by a water-cooled
Benz Bz.IV straight-six engine that drove a wooden, fixed-pitch, two-bladed
propeller. The aircraft's armament consisted of a fixed, forward-firing
LMG 08/15 Spandau machine gun and a 7.92-mm
LMG 14 Parabellum machine gun on a flexible mount for the observer. Three prototype aircraft were built with the second aircraft destroyed during
static load testing in June 1918. It was not chosen for production. ==Specifications==