The challenge comes from one of small number of cities where learning and flying went hand in hand
Don't forget, that between the wars, Germany was not allowed to develop advanced aircraft so gliding and lightplanes were used to move the design process forward, not from a major manufacturer but from one of these University flying clubs
Search wiki for
Akademische Fliegergruppe don't go too far down the list and stay away from where Reg lives!
There are a number of aircraft of the same year, that's where the King/Emperor's name (in German) will zero in on the challenge.
Our next King (unless he stands down) will have the same name, but not in German!