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Old 04-22-2020, 02:40 PM   #24 (permalink)
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turning wheels/undercar

Originally Posted by JulianEdgar View Post
Historic data is always interesting, but quoting wind tunnel test results for wheel drag when (1) the wheels weren’t turning, and (2) the undercar airflow was completely different, is not likely to be helpful when discussing wheel drag on current cars.
General Motors explored moving-floor wind tunnels in the early 1950s,and reported that the variability of drag data,as a function of the moving wheels was statistically insignificant,and the difference could easily be compensated for during static wheel testing,deeming the extra trouble not worth the effort as far as cost/benefit/accuracy.
As to the underbody flow,I'm unsure where the disconnect would be,compared to contemporary facilities.They were suctioning the tunnel floor,to prevent boundary layer buildup,which appeared to be the sole concern.'Windage' effects of rotating tires to wheelhouse and underbody flow had been explored.
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