Heinkel HD 39

The Heinkel HD 39 was a special-purpose cargo aircraft developed in Germany in the 1920s to distribute the Berlin newspaper B.Z. It was a conventional single-bay biplane with staggered wings of equal span and a fuselage that nearly filled the gap between the wings. Its sole example was built after Ernst Heinkel learned by chance that the paper wanted such an aircraft and had ordered two from Albatros, and he persuaded the publisher Ullstein-Verlag to buy a third from his firm. Based on the HD 27 mail plane, it had a specially designed bay carrying newspapers in 50 kilogram bundles, with ten compartments that could be opened in flight to air-drop papers where it could not land. It entered service in April 1926 and remained in service until 1931, when Deutsche Luft Hansa took over air distribution of the paper.