Originally Posted by bookworm
With your symmetric aerofoil, I'd agree that the average Cp is negative. But for the flat plate it's most definitely positive.
I did say this in my discussion of Q240 in my original post. Flat plates are effectively "Newtonian".
Yes, FoilSim's great fun. I particularly like the way it's open source and the user interface can be tweaked to demonstrate specific applications (like the baseball demo).