attn: resident aerodynamicist

[Alastor187]

Originally Posted by Nereth

The same logic applies when the air is pushed up by a car. And yes, in profile, the body goes up just as much as it goes down.

True, although it doesn’t necessarily follow the same slope (in magnitude anyway). As well, this doesn’t imply that the forces some how cancel, there is still lift at some point and downforce at another. Both of these points are likely to be on opposite ends of the body.

The point I was trying to make was that saying the upper surface of the car is longer than the bottom therefore it is an airfoil so it creates lift is an over simplification of both airfoils and vehicle aerodynamics.

For airfoils the upper surface doesn’t need to be longer to create lift. If you turn a classic wing shape upside down it can still create positive lift given enough angle of attack. Otherwise how would a plane be able to fly upside down?

Likewise, the upper surface of a car, while longer than the bottom, is not a smooth curve. So the flow over it will be complex and vary from transition to transition. Certainly, there are generalizations to be made, but they are just that.

[Nereth]

Originally Posted by Alastor187

For airfoils the upper surface doesn’t need to be longer to create lift. If you turn a classic wing shape upside down it can still create positive lift given enough angle of attack. Otherwise how would a plane be able to fly upside down?

Actually... when they fly upside down with a high angle of attack, the stagnation point moves down (in side view, with plane upside down), such that the effective 'top' is still longer than the effective 'bottom'.