rplumbo,

What you need to do is a surface integral of pressure. You won't quite get that the way you describe it. I see two ways to get started on this problem. One is to find some measured coefficient of pressure data for a deflected control surface, and use the flight speed and area to approximate the force. The other is to make a bounding assumption, like the drag on a flat plate perpendicular to the oncoming flow. The data needed for the second approach can be easily looked up. For the first, I am not sure.

banktoturn