Developed by Hubert, the first version of the P 13 was a tailless high-speed bomber, with fore-and-aft tandem propellers and two piston engines.
A completely different plane, designed by Lippisch, also was called the P 13 (actually P 13a). The P 13a was designed to make use of an unusual fuel source for an airplane: coal. Liquid fuel was getting scarce, and a plane
which could burn coal products would have been very desirable.
Wind tunnel tests of the P 12 and P 13a and tests of free flight models were very successful, and did not reveal any problems.
Another version of the P 13 had a much wider wing, and used a cylindrical combustion area.
Still yet another version of the P 13 became the DM-1 full scale flight test model