Ideas had been tossed around as early as the s but officially, a basic project was not even finalized until April The idea waxed and waned until being cancelled a final time in It was also the least capable of filling the range and payload requirements. Only two Mes were built. Both were destroyed on the ground, as was an unfinished third. This is actually an airbrushed photo of a scale model.
No complete He ever flew. Several versions were proposed, one being a reconnaissance model with a much higher ceiling but insufficient range to reach the USA. The engines were liquid-cooled models, seated side-by-side, using a large annular radiator behind the propeller which gave the nacelle the appearance of housing one giant air-cooled radial. This caused problems with mechanical failures, oil leaks, overheating, and engine fires which plagued the He throughout WWII. Bundesarchiv photo.
The dive bombing requirement was rescinded and its features were omitted after early production batches.
However the Luftwaffe was keen to keep He production rolling and ordered that the coupled arrangement be retained. Heinkel had been wary of this arrangement even while the He was still on the drawing board. With it in service, the company explored several options for taking the basic airframe and adapting it to a more sensible four-nacelle, four-propeller arrangement.
One of these was the aforementioned reconnaissance version of the He proposal. A separate project within the company was the HeH, basically a He with four separate engine nacelles. It was originally envisioned to be a strategic bomber with sufficient range to hit London from unorthodox directions, for example from bases in occupied Denmark. These efforts were all incorporated into a separate offshoot, the He, a high-altitude reconnaissance-bomber.
