The unarmed prototype first flew in May or June 1915, named KD.15 and powered by a Rapp engine.Harris, 2007 p.163 Production examples were given the official designation C.I and the observer was provided with a single machine gun for defence.Grosz, 1995 The Rapp engine proved unreliable so production aircraft were also equipped with the lower-powered Mercedes D.III or Benz Bz.III.
