Heinkel HD 20

The Heinkel HD 20 was a twin-engine, three-seat German biplane built in 1926 for civil survey work. HD stood for Heinkel Doppeldecker, meaning Heinkel biplane. It was a single-bay biplane of mixed wood and steel construction with fabric covering, the upper wing being much larger than the lower, and V-form interplane struts that also carried the two engines. Those were Wright R-790 Whirlwind nine-cylinder radial engines of 150 kilowatts each, mounted in streamlined cowlings. The fuselage was a fabric-covered steel tube structure with three open cockpits, and the wheels could be replaced with floats. Little is known of its history: the first flight was probably in late 1926, the number built is unknown, and one civil example owned by an advertising agency was destroyed in November 1929. It is also mentioned as a photographic survey aircraft in a 1930 review.