Textbook aerodynamics specialists should really fly and or watch a few really good flat foam models perform before they make any decisions as to what is/is not a good airfoil for this type flying.
The textbooks apparantly don't include this type flight .
I am constantly being asked if a "proper" airfoil would not improve performance.
The flat foam panels are proper -for this application.
They operate perfectly under a relatively wide speed range and at ANY angle of attack.
What the hell else could you ask for?
The bookshelves of "airfoils" were intended for specific tasks - -none of them being THIS task