Originally Posted by ibillwilson
But what about the KFm1? It seems to be a different animal altogether. Does the entrained vortex theory explain the effectiveness of the bottom step for mitigating stall?
FWIW...My personal take on it is that the flat upper surface of the KFm1 operates part stalled almost all of the time. Hence no sudden onset of stall and no sudden drop in lift. Stall becomes a more gradual process. The down side is that operating partly stalled most of the time drastically increases drag.
Others may disagree, and that's perfectly fine, however I've yet to see any sensible explanation as to how a step on the bottom of an airfoil could prevent flow separation on the top of the airfoil
... After all, the air flowing over the top of the wing has no 'idea' what the bottom of the wing looks like