Dornier Do K

The Dornier Do K was a single-engine, high-wing monoplane passenger transport aircraft in the early 1920s. Although identified by the same code, the model was produced in three different prototypes, each with different engines and airframes, ranging from the single-engine Do K1, with the engine located in the nose, to the four-engine Do K2, with two pairs of engines in a push-pull configuration located in two underwing nacelles, to the Do K3, with a similar propulsion solution but a new fuselage and new wing. Source: Wikipedia