When you look at a typical Coefficient of lift curve in a publication, they always stop just past the Cl
max point. See example below:
Did you ever wonder why they don't carry on further to the right? It is because past that point, it gets a lot more complicated, varying with aspect ratio, thickness ratio, and Reynolds Number.
A typical extended curve looks more like this:
The double humped curve shown above is rather typical actually. Now we have a clue where the notch in the Viper pitching moment curve comes from.
Fortunately the wind turbine industry has need of post stall airfoil performance and someone has studied the subject a bit. The following pdf file is on a slow server, so give it some time to load.
http://home.comcast.net/~shademaker/...tStall44XX.pdf
I researched this topic a bit because I was interested whether or not AF447 was likely to get stuck in a pitching moment notch of its own. Maybe so, but the THS lower aspect ratio than the wing indicates decreased likelihood of having as much of a notch as the wing might have, i.e. more nearly linear performance.