Quote:
Originally Posted by Vman455
I wonder how Cd is actually calculated in a wind tunnel? Is it derived from total drag force and calculated frontal area? If so, that leaves a lot of room for fudging--er, estimating--numbers.
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From: Drag Force = ( 1/2 X rho X Cd X A X V-squared ),
they measure the actual axial drag force,then using actual station pressure,calculate the air density at test time,then using the projected frontal area,and actual test section air velocity, squared,the coefficient falls out of the equation.
To complicate matters,the EPA does not recognize the frontal area of the side-view mirror(s).
The drag reflects the actual frontal area,including the mirrors.
If the drag is mandated to reflect frontal area sans mirror(s),then the coefficient of aerodynamic drag will be arbitrarily high.
A marketing statistician could 'cook' the numbers.
It's regulated ambiguity.
