Ask A Scientist© Environmental Earth Science Archive

name         Dale
status       other
grade        other
location     AR

Question -   If dimples on a golf ball make resistance less to air in
flight, then why do cars have a smooth finish? If I had the little
dimples on my car, would I get better fuel mileage due to less wind
resistance? And where can I learn more about airflow over objects? 
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The aerodynamics of a golf ball and a car are very different, in size,
shape and mode of flight. If your car were spinning at the rate that a golf
ball does (scaled up of course!), dimples might help, but I doubt you would
be able to appreciate the difference.

Vince Calder
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The dimples on a golf ball have gotten very sophisticated.  The old 365 same
depth and size have given way to more, of different shapes and depths.  The
result is one can get a ball for any desired characteristic.  High flight,
low flight, one to resist curving ( slices).  In all likelihood the same
could be done to a car, but one would think the effect would be small
compared to everything else.  The spoiler is added to keep the car low to the
ground, but you see it is large.  All the add-ons, like mirrors and handles,
seams at the windows, all those items affect the wind resistance.  The same
goes for the shape and finish.  The wind tunnel studies yield the possible
benefit.  Factor in the car's weight.  I recently heard about the cheating in
NASCAR.  Apparently, years back Jr. Johnson had a car built to 7/8 size, all
the parts etc.  No one could tell why he was winning the races, but that
small edge was big.

About finding information... Google.  But sometimes engines like Ask Jeeves,
do better with questions.

James Przewoznik
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