They not only pull more air over the upper surface of the wing, but they also create an additional leading edge (or several, if the flap is double- or triple-slotted) with its own stagnation point ...
Here are the critical aspects of this design: Full-Span Flaps The MU-2's wings utilize full-span double-slotted Fowler flaps instead of having separate ailerons. This design choice allowed for ...