Does anyone have a handy rule of thumb for how much the deflection of a plain-flap-style control surface effects Cl and Cm (in the no-separation regime, say less than 15 degree deflection)? For a 25% to 30% flap, my own 2D panel codes give numbers of 0.08 Cl/degree (consistent across a wide variety of airfoils) and 0.01 to 0.02 Cm/degree (with higher variance). Other tools I've played with (JavaFoil, for example) give very similar numbers... but at least the Cl numbers seem surprisingly high. Does anyone else have an approximation they use? Or can anyone say "yep, this seems right"?