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Old 05-04-2011, 03:27 PM   #11 (permalink)
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Quote:
Originally Posted by aerohead View Post
The only variable you can have is the shape of your car.
Yup. Watch for warm-up time, temperature, humidity, and very slight crosswinds, too.

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Old 05-05-2011, 11:58 PM   #12 (permalink)
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Originally Posted by NeilBlanchard View Post
You will have to do a coast down test. Here's the Instructables page and spreadsheet I used:

Measure the drag coefficient of your car
Hi Neil, I printed this a few weeks ago thinking I would do the calculations. Studying it brought me eventually to the end of the pamphlet, where the author says there are more variables than he originally thought and so the formula might not work well. Do you have a way around that problem? It's also too late for me to calculate a baseline.

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Old 05-06-2011, 05:58 AM   #13 (permalink)
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The main variable is the rolling coefficient of the tires -- I just used the lowest end of the range, since I know that having my tires pumped up lowers the RR. The other things like barometric pressure or elevation, I just took the default or my best guess (I used Google Earth to get an elevation).

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calculation, drag coefficient, formula, improving drag, measuring drag

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