[JulianEdgar]

Originally Posted by aerohead

Customarily, the drag force is only the net, horizontal, axial force, generated by the pressure differential from front, to rear, expressed in terms of the projected frontal area. It's just dynamic pressure times CdA. ( 1/2 x rho x Cd x A x Velocity-squared )
Take the drag force, at any velocity, then divide by the frontal area, and you'll get the net force per unit area, as a function of delta-P.
Hucho felt that since bluff-body automotive drag is ruled by pressure drag, and pressure drag was a function of flow separation, then the rear base pressure would be of paramount concern as regarding drag.
I've never seen any text in which this concept wasn't promoted.
We would treat any vertical components separately under lift.

I am sorry, that doesn't seem to have answered the point that base pressures do not need to be similar to body pressures at the point of separation. Wasn't that what you were saying?