Heinkel HD 16

Bild: Wikimedia Commons

Another German-Swedish collaboration, the HD 16 reconnaissance aircraft first flew in 1928 as a refinement of earlier designs. Measuring 13 metres long with an 18-metre span, it achieved 196 km/h—a modest improvement reflecting incremental engine and aerodynamic development. The aircraft suited extended reconnaissance missions where endurance and observation capability mattered more than outright speed.