Only issue I have with this article is that there was no add to cart button.
Would like to know more about the airfoil, how it was designed. Article just says it is “undocumented”.
A lot of ultralights use an airfoil that is pretty informal, as there are fewer ribs, and the fabric billows a bit. I don't know if that's the case here.
More camber and narrower nose than NACA 4412. Less extreme than S1223. For what it's worth...