bombloader, there are a lot of factors (and a lot of centers of pressure) in pitch (unless the wing is Hershey-bar shaped, the Cp of the airfoil is different from the Cp of the wing...which is different from the Cp of the complete aircraft), but as far as yaw stability goes, Bicycle Bob has got it:
Quote:
Originally Posted by Bicycle Bob
A major problem with stability is that a streamlined shape of constant density will have the center of pressure, or lift, ahead of the center of gravity, so it naturally wants to tumble.
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A ground vehicle viewed from the top is nearly always symetrical, and a symetrical airfoil has (for all practical purposes) its Cp at 1/4 of its overall length. To be (aerodynamically) yaw neutral in side gusts, the CG and Cp need to be in the same place (viewed from above), and man that's tough without adding some area behind the CG.
I think most aircraft designs (most of mine for sure) don't have an overabundance of yaw stability--enough to get the job done is the goal; too much adds drag for no reward and makes the controls heavy--but the books are full of aircraft which had fuselages modified for better streamlining and suddenly found they needed more vertical fin. I suspect the same is true for automobiles; the better the streamlining, the more challenging the stability issues.