It is the “Ost-Deutsches Automobilwerk”, makers of Trabant cars. They have seen their engines used on motorized gliders.

“Oda-Trabant”

-The Trabant engine has two inverted in-line cylinders. It is two-stroke with a displacement of 594.5 cc and it gives 26 hp at 4,300 rpm. (with unleaded gasoline).

From Appendix A5/6: The Trabant engine manufactured by Ost-Deustches-Automobilwerk was installed on airplanes. Its position in the car was vertical and transversal as we see below.

"Front end of the Trabant"