The Heinkel He 116 was an extremely long-range mail plane designed and produced by the German aircraft manufacturer Heinkel.
It was designed during the latter half of the 1930s to fulfil a request by the German flag carrier Deutsche Luft Hansa for a suitable aircraft to carry long distance airmail between Germany and Japan. Derived from the He 70, furnished with an all-new semi-monocoque duralumin fuselage and powered by a total of four newly-developed Hirth HM 508C V8 inverted piston engines, the He 116 was designed specifically for this role, specifically the airline's route over the Pamir Mountains in Afghanistan. On 9 December 1936, the prototype performed its maiden flight; further aircraft were produced over the following two years.
A total of eight He 116As were produced for the mail plane role, however, the type was not only used in a civilian capacity. At the behest of the Reichsluftfahrtministerium (RLM), a pair of He 116Bs, which were specially adapted for long-range reconnaissance and bomber missions (including the use of a fully glazed nose similar to the Heinkel He 111) were created. Additionally, a single He 116R, featuring an enlarged wing, increased fuel tankage in the fuselage, and four Hirth HM 508H engines that provided superior fuel economy at lower rpms, was built for a successful record-setting flight, covering an unrefueled distance of at an average speed of , conducted on 30 June 1938.
Development and design
Work on what would become the He 116 commenced in response to a request made in 1936 by the German flag carrier Deutsche Luft Hansa for a new long-distance mail plane. At that time, the airline was planning several long distance routes, in both the South Atlantic and the Far East; for the latter, it envisioned a route over the Pamir Mountains of Afghanistan. This was the primary difficulty in producing an aircraft able to meet the range requirements, because the aircraft would have to lift its large fuel load to an altitude of at least to clear the mountains. At the time, there were simply no engines available with that sort of altitude performance, although Hirth was working on one in the class. The Günter brothers proposed to adapt their basic He 70 Blitz airframe to carry four of these engines to provide enough power for the massive fuel load.
The He 116 adopted a modified version of the He 70's twin-spar elliptical planform. No service use of the type by the Luftwaffe is believed to have ever taken place. Jane's all the World's Aircraft 1938
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