Heinkel HD 17

The Heinkel HD 17 was a German military reconnaissance biplane of the 1920s. It was a conventional single-bay design with strongly staggered wings of unequal span braced by N-type interplane struts, with the pilot and observer sitting in tandem in open cockpits. It first flew in 1924. In 1926 the Reichswehr evaluated it for the secret aviation training school at Lipetsk and chose it over the competing Albatros L 65; seven aircraft were bought and used briefly for training before more modern designs replaced them. Two HD 17s were also evaluated by the US Army Air Service in 1924, modified by Cox-Klemin to take a Napier Lion and a Liberty engine and designated CO-1 and CO-2, but they were rejected and returned. The CO-1 had a length of 9.48 metres and a top speed of 240 kilometres per hour.