Quote:
Originally Posted by josemapiro
Hi t vago
Thank you the website is perfect for the calculation.
In relation to the test, the speed at which the test should be performed is important?
Should it be the same speed or should it be with different speeds?
What is the speed range that you think is the most suitable for the test?
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I think that should be a low-speed test, at about 40 or so km/h. This should be used primarily to determine the coefficient of rolling resistance. Aerodynamic drag, viscous drag, and lift should not factor in during low-speed testing.
Quote:
Originally Posted by josemapiro
Hi t vago
I know the value will be given by the code, but what the (Cv) means the other two I know, this is that I could not find out what it is.
(Cd) - Coefficient of drag
(Crr) - Coefficient of rolling resistance
(Cv) - ?
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That would be viscous drag, which apparently is not accounted for anywhere else in literature discussing how to perform coastdown testing. Likewise, aerodynamic lift is not accounted for anywhere else. I think that viscous drag may not matter too much, and might even be a negative number for newer cars. I simply don't know.
As for determining lift and coefficient of drag, that will prove to be tricky as both are functions of the square of velocity. Both terms only show up under moderate to high speeds. I think lift shows up at a higher speed than drag, though. Again, I simply don't know for sure.