Quote:
Originally Posted by winkosmosis
That statement can't possibly be true 100% of the time, because a teardrop shape can be more aerodynamic than a cylinder with the same frontal area.... Like I said, if the Cd improvement is bigger than the frontal area increase, drag goes down.
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Hucho's Cd curve for roof camber shows the drag reduction asymptotic when the elevation of the 'bump' is around 0.11 X car height,yielding a drag reduction of 5%.
If the 'bump' adds no more than 5% to frontal area,then aerodynamically it's a wash.The drag saving is canceled by the increased frontal area.CdA remains constant.
The challenge is to get the optimum roof camber with 5% Cd reduction while adding less than 5% frontal area.