Just how important are the fluidic properties of air at 50 mph on a highly deflected 3D type control surface?
Relatively (in air) slow speed, high deflection angle, large surface... it would seem that his computation might not be completely accurate, but close enough for gov't work. Or, are the factors not taken into account significant for what he wants to model?
Tim
Originally posted by JimTrainor
Before you dive into the calculus, be sure to get the basic physics correct. You have to account for the change in momentum of the air flow. You need to know the flow in, and the flow out (direction and speed of both). With that info you can perform your momentum balance (or force balance if you prefer to look at it that way.)
The flow out is the tricky part - to get a useful answer you'd have to simulate the fluid flow. (This is where you open the proverbial can or worms.) If you did that, then you'd also have pressure distribution data and you could easily compute the net force (as banktoturn noted).
Have you considered existing airfoil simulation software? There is some free stuff floating around. For example, xfoil.
If you can describe the surface (tail surface plus deflected surface) and if you can get the software will spit out a pressure distribution, then you're home free.
If you get that far, please add boost tabs and tell me if they really have any meaningful effect 
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