In 1937, Dornier obtained a patent for a plane with two engines in the
fuselage, driving the pull and push propellers. The design was marked
P.59, and its concepts were refined in 1939 in the P.59-05 variant,
after which the design was put in a drawer. This type of plane was not
needed at the time. Nevertheless, limited experimental work was carried
out, the result of which was a small Goppingen Go-9 plane, with an
aerodynamic system obtained from P.59, as well as three-support landing
gear with a front wheel and an engine driving a push propeller through a
long shaft.
The results of these experiments were used when designing the P.231
aircraft in several variants--also combining piston and jet propulsion.
When in 1942 the RLM announced the requirements for a high-speed
multipurpose aircraft, the equivalent of the British Mosquito, Dornier
proposed the P.231 as a rather unusual answer. Despite the risks posed
by the different P.231 concept, Dornier was commissioned to build
several prototypes.