Heinkel HD 40

The Heinkel HD 40 was a special-purpose cargo aircraft developed in Germany in the 1920s to distribute the Berlin newspaper B.Z. The success of the earlier HD 39 for the same publisher led to an order for a similar aircraft with greater capacity, and Heinkel answered with a considerably enlarged machine of the same layout, a conventional single-bay biplane with staggered wings of unequal span. The wings were wooden, and the fuselage was welded steel tube skinned in plywood. As well as the newspaper bay it had a second compartment that could quickly be changed between extra cargo and seating for up to eight reporters or passengers. After only six months in service the aircraft was destroyed in a crash caused by engine failure. Its wingspan was 17.6 metres and its BMW VI engine produced 447 kilowatts.