ORIGINAL: Korps
Minn, the under-cambered type - never seen it before. Which types of planes has that?
I don't know if they are properly named, but a wing formed by a cambered plane is known as a Jedelsky wing.
Now, a flat plane, like the one used in foamies, operates on the principle of a symmetrical airfoil; only that it is a less aerodynamic shape and produces more drag.
However, for slow velocities, like in 3-D flight, drag is not important.