> It's not as simple as v^2, you have to consider the compressibility effects (wave drag where the pressure wave moves along with the plane, like a bow wave on

> It's not as simple as v^2, you have to consider the compressibility effects (wave drag where the pressure wave moves along with the plane, like a bow wave on a ship). I think it is that simple. Those effects are the reason the drag coefficient is changing, you don't need to account for that twice.