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Old 04-22-2009, 11:35 AM   #1 (permalink)
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Repainting a car for Aerodynamics?

I really need to repaint my car.... 30yo paint... crappy 1st attempt at repainting/bodywork/restoration on half the car... so I'm wondering about any effect on aerodynamics

Thoughts:

1. Non-Smooth/Matte Surface
2. Glossy Surface (I'm thinking this may be the least aerodynamic)
3. Textured Surface (i.e. GOLFBALL )

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Old 04-22-2009, 02:32 PM   #2 (permalink)
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I think the general knowledge on this subject is that air doesn't really glide along the surface of the car as much as slightly above it, so how smooth it is to the touch really doesn't make any difference.
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Old 04-22-2009, 02:38 PM   #3 (permalink)
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Paint won't make any difference, except possibly from its added weight . Other than the very front of the vehicle (where flow may be laminar), the air in the boundary layer immediately over the paint surface is already turbulent.

So golf ball dimples will have no effect.

And that's also why washing/waxing makes no difference. (Unless you're washing off great hunks of mud, or birds & small animals.)
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Old 04-22-2009, 02:58 PM   #4 (permalink)
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Quote:
(Unless you're washing off great hunks of mud, or birds & small animals.)
LOL... priceless sig material right there

I didn't know... figured it would be worth asking. Guess in the case of a Golfball its "spinning" so at any one moment the surface of the ball somewhere is coming in contact with air movement
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Old 04-22-2009, 03:18 PM   #5 (permalink)
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Never hurts to ask. (Unless someone yells at you to use the search feature )

With the golf ball, the dimples aren't really about spin/no-spin. They help reduce the size of the wake behind the ball by tripping laminar flow into a turbulent boundary layer, which permits the point where flow completely separates from the ball to happen further back.

(Since a car already has a turbulent boundary layer, that's why adding dimples won't help anything.)

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Old 04-22-2009, 03:44 PM   #6 (permalink)
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USE THE SEARCH FEATURE!!!!!!!!

Or, you could just listen to MetroMPG... he's a smart cookie!

*Sorry, had to do it.*
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Old 04-22-2009, 03:55 PM   #7 (permalink)
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I've heard of people painting their cars with anti-radar paint, but maybe this should go in the speeding thread
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Old 04-22-2009, 04:22 PM   #8 (permalink)
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And a pretty picture!



From: Fore! Here Comes the Ultimate Golf Ball | LiveScience

There's some video at that site too, if you're interested.
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Old 04-22-2009, 04:41 PM   #9 (permalink)
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actually near the end of WW2 american warplanes where left bare metal, in part to save weight. (but also because in this stage in the way planes rolled out of factories faster than the axis could shoot them out of the sky...)

anyway, if you have an aluminum car like an audi A2 or a delorean you could save a few more grams by not painting them.

if you paint the car choose a relaxing color, this will cause you to drive slower and save gas!
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Old 04-22-2009, 05:01 PM   #10 (permalink)
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You could also wait a bit longer (what's another year?) for PhotoVoltaic paint, which will help ease the costs of the alternator, and get you better FE.

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