Heinkel HD 19

The Heinkel HD 19 W, also known in Swedish service as the Svenska Aero J 4, was a biplane seaplane fighter developed by Ernst Heinkel Flugzeugwerke. It was the only naval fighter ever delivered to the Swedish Air Force, which in 1927 asked for an aircraft to defend coastal fortifications and navy ships. The specification fixed both the engine, a Bristol Jupiter VI, and a floatplane layout. Two aircraft were ordered from Heinkel in September 1927 and four more from its Swedish branch Svenska Aero in October 1928; deliveries ran from May to September 1929. Armed with fixed 8 millimetre machine guns and a flexible gun for the observer, it was limited by its floats, and was used mostly for reconnaissance and fire direction. The last J 4 was withdrawn on 31 August 1937 after 812 flight hours.