The Dornier Do 20 was a planned large flying boat Dornier-Werke .
The flying boat was designed in 1935 as a further development of the Dornier Do X The structure resembled largely the Do X.. The largest change was in addition to an aerodynamically refined fuselage, the engine assembly. So eight diesel engines were provided with an output of 800 hp to 1000 hp, each for two drives a propeller through a coupling mechanism and a remote shaft. The number of propellers thus reduced compared to the Do X from twelve to four pure tractor propeller. It was intended to carry up to 2000 kg payload and up to 60 passengers. Since the German Lufthansa gave no order to the development, the project was not realized.