Quote:
Originally Posted by drmiller100
what you wrote makes no sense to me.
I don't compare fish to birds. I don't compare tractor trailers to hatchbacks.
Comparing Cd is worthless between the two.
Cda is what matters, because if you combine speed, Cda, and weight, you can KNOW the drag of the car.
Cd is a way to sort of calculate Cda, but it is kind of worthless by itself.
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The Cd of a car would give a potential consumer the same information as the thermal R-Factor for doors,windows,walls,and ceiling in a prospective home purchase,as the inverse of R-Factor is the Heat Transfer Coefficient for the home.A thermal Cd if you will.
The square footage of the home wood give an overall sense of energy efficiency as would the frontal area in a vehicle.
It is quite proper to compare Cds of aircraft,birds,submarines,bullets,fish,radomes,'n such,as they are all subject to the same forces and we can learn from their performance vs shape.