Interesting observations of airflow splitting around the fuse and hitting either the top or bottom of a wing panel... Anyway, when a flyer commands rudder (right or left) on a plane with a flat bottom airfoil and some degree of dihedral, the yawing action actually causes one wing to increase in airspeed slightly, and generate more lift, as the rudder pushes the tail of the plane to one side. These two actions together will typically cause a trainer type plane to bank and initiate a turn. One must also usually pull on the elevator to push the tail around in the corner. It can also be seen, often to less extent, in symmetrical airfoils as well.

Lachlan