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Old 01-16-2019, 03:54 PM   #87 (permalink)
JulianEdgar
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Quote:
Originally Posted by freebeard View Post
Why, the elevation changes?

Bidirectional passes on 'level' ground would cancel out effects of wind. Multiple downhill passes take twice as long but wouldn't the gravity assist act as a multiplier for the effect your trying to measure? A vehicle that maintains a steady coasting speed will be more aerodynamic than one that loses speed, and less aerodynamic (plus RR) than one that gains speed on the test section.

I've been wrong before.
I describe in the book using a constant gradient, long downhill slope to do comparative speed testing in different drag configurations. Using a 10Hz updating GPS digital speedo, I got results that were:

1. consistent in the one drag configuration
2. made sense in the speed variation versus the different drag configurations
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