Originally Posted by springer
Not sure how to interpret the moment coefficient anyone have a good explanation of interepretations?
Didn't see any reference to moment coefficient, but it's a measure of how much the wing tries to pitch down. In general, the more camber an airfoil has, the higher the moment coefficient. It can lead to instability for highly cambered wings in high speed flight, ultimately overcoming the ability of the tailplane to keep the nose up - since the moment coefficient stays roughly constant as the lift coefficient reduces in faster flight. Most high speed planes therefore have low cambered airfoils. On a tailless design, reflex airfoils were traditionally used featuring near zero moment coefficients.
The maximum lift coefficients of the KF airfoils are impressive. Forcing the boundary layer to become turbulent is clearly beneficial at the low Reynolds numbers you get in models.