Anyone know anything about the German Aircraft-Construct HX I helicopter plans?

[HobbyCAD]

I have an electronic copy set of very detailed helicopter design drawings called an HX I, cannot recall how I came about them. The plans are in German and English, the designer seems to be Aircraft-Construct. The mechanics seem to be designed well, extremely detailed drawings there, the body and tailboom structure is all sheet metal. The drawings are down to part for part laser-cut design file level, it seems complete.

Does anyone know anything about this machine?

Cheers, Francois.