I was leafing through the C172N POH for some flap settings yesterday and a
thought occured to me: there was a post here about some verions of the 172
having different full flap angles - some have 40 and 38 degrees. So i
wonder, how do they determine these angles for all flap settings when the
plane's still on the drawing board? Or is it an airfoil design thing? I've
noted that for example the Learjet 45 has first setting at 8 degrees. How do
they determine what is the right angle for each setting?

Triple Delta