Indeed. I once got into a discussion with someone who challenged by assertion that I could build a plane with NO airfoil at all, just a plank with an angle of attack of about 55 and it would fly.
He laughed at my ignorance of things aeronautical - until I took one of my RC models and fitted it out with a totally flat wing; a slab of balsa, it was, and flew it in front of him.
Indeed, most wing shaping is done in the pursuit of drag reduction and controllability.
He who laughs last laughs best.
That’s not 55, it’s 5%.
“Indeed, most wing shaping is done in the pursuit of drag reduction and controllability.”
And stall characteristics. That would probably be under control-ability.
This is a contradiction in terms, since "a plank with an angle of attack of about 55" is no other thing than an airfoil, however inefficient.
A debate was raging about the shape of the wing, and one of the lead engineers reportedly fitted a piece of flat plywood, cut to a triangle the size of the proposed wing, to the clamp in the wind tunnel and it produced every bit as much lift as any “engineered” design. All displacement lift.
An example of displacement lift can be found in aerobatic wings, sometimes with curved upper and lower portions that are equal.
He laughed at my ignorance of things aeronautical - until I took one of my RC models and fitted it out with a totally flat wing; a slab of balsa, it was, and flew it in front of him.
As a fellow R/C pilot, I need to remind you the Reynolds numbers that our models fly at compared to the Reynolds numbers of full scale aircraft.
Scale-wise, the air is much thicker to our models, and many such tricks as 3D hovering on the prop are easy at our scale, but has rarely been done full scale. (The Pogo being one full scale example.)
That being said, you could have just asked your friend if he's ever witnessed a full-scale aerobatic plane fly inverted. Or knife edge.