Quote:
Originally Posted by JulianEdgar
I don't think that you can state that wake base pressure reflects body pressures at the end of the vehicle.
There are numerous pressure plots available of vehicles - some show similar pressure in the base area and trailing parts of the body, but many do not. The coloured pressure plots I posted above don't, and nor do the following:
I also had a good look through my reference library yesterday and could find nothing that supports the idea.
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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.