# [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics



## EVDL List (Jul 27, 2007)

Interesting. A few months ago Pop Sci had an article about a company that
made dimpled vehicle wraps claiming to increase mileage. They failed to
check with their sister publication Pop Mechanics who actually tested the
same product earlier and found it did nothing. The theory was that a golf
ball works because it's spinning while a vehicle obviously does not, or if
it does you have greater problems than mileage. The dimpled wraps were
rather shallow so maybe deeper contours would make a difference, though I'm
still skeptical.




> SLPinfo.org wrote:
> >
> > Hey folks,
> >
> ...


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## EVDL List (Jul 27, 2007)

I talk to my body man at the caf=E9 this morning about this. He said they =
put =

in carbon fiber sections on a NASCAR race cars that does same effect. I =

also seen this dimple carbon fiber panels on jet fighters which reflect the =

radar.

The Ferrari Contach Group 7 race car has this type of carbon fiber surface.

Another way to reduce the air resistance is to design the frontal section o=
f =

the vehicle wide open and duct it out over the vehicle. He show me a Cam-A=
M =

Group 7 race car that he is working on, it has the windshield and front =

slope steep to 2 inches about the ground.

It has a 4 foot wide air opening that is ducted under the front end and exi=
t =

up over the wind shield. These cars a mid engine, so the whole front end i=
s =

empty. This things only weighs 1300 lbs.

Roland


----- Original Message ----- =

From: "SLPinfo.org" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, October 22, 2009 9:58 AM
Subject: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics


> Hey folks,
>
> Saw an episode of Mythbusters last night - they began by testing if a =

> dirty
> car gets better gas mileage than a clean car (based on the assumption of a
> dirty car giving a "golf ball effect" - the dimples on a golf ball break =

> up
> the airflow and result in better aerodynamics). Well the dirty car got
> poorer gas mileage so the initial myth was busted. BUT then they created =

> a
> car with a truly dimpled surface that looked a lot like that of a golf =

> ball
> (dimples enlarged to the scale of the car) and it improved gas mileage by
> 11% over a smooth surface on the same car. Here's a link:
>
> http://dsc.discovery.com/videos/mythbusters-dirty-vs-clean-car/
>
> For those who are perhaps up to custom designs, making body panels with a
> dimpled surface could potentially improve range. Doing it on the sheet
> metal of an existing car would be extremely difficult to do (as they
> explained in the episode). They used a clay material added to the outside
> of the car for the test.
>
>
> - Peter FLipsen Jr
> http://www.evalbum.com/1974
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## EVDL List (Jul 27, 2007)

Myers motors has been using this effect on the NMG for a while:
http://tinyurl.com/yl9qhvf

And of course Homer Simpson is way ahead of the curve:
http://www.urbandictionary.com/define.php?term=3Dspeed%20holes



> SLPinfo.org <[email protected]> wrote:
> > Hey folks,
> >
> > Saw an episode of Mythbusters last night - they began by testing if a dir=
> ...


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## EVDL List (Jul 27, 2007)

Wow, thanks Bill, that's an eye opener. Very interesting.
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## EVDL List (Jul 27, 2007)

> AMPhibian wrote:
> > A few months ago Pop Sci had an article about a company that
> > made dimpled vehicle wraps claiming to increase mileage. They failed to
> > check with their sister publication Pop Mechanics who actually tested the
> ...


----------



## EVDL List (Jul 27, 2007)

Re: dimple size. They scaled the dimples up from the proportions of the
golf ball to the size of the car. The dimples were quite noticable - if I
had to guess they were about the size of half a baseball. I have to believe
that the golf ball companies have figured out precisely how big the dimples
should be and scaling up would be an appropriate thing to do.

Re: dimple placement. They observed a noticable positive effect by putting
dimples everywhere. Given their findings, then if Bill and Lee are right,
selective placement of the dimples would result in even better fuel
efficiency than the 11% they found! All the more reason to at least
consider them in vehicle design.

- Peter Flipsen Jr






> Lee Hart <[email protected]> wrote:
> 
> > AMPhibian wrote:
> > > A few months ago Pop Sci had an article about a company that
> ...


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## EVDL List (Jul 27, 2007)

Bill,
Those equations look hauntingly familiar. In fact I think Maxwell 
actually derived his equations from the mathematical work already done 
in the field of fluid dynamics. Which lends credibility of the phrase 
"the water pipe theory of electronics" ;-)

But on the larger airliners though they also do this with those fin 
looking vortex generators, but basically the same concept right. Make 
it slightly turbulent and the flow won't separate. But without them the 
flow gets so turbulents and large sparations in the laminar flow occur.

I wonder if any of the LSR racers are employing this degree of aero 
enhancements?

Mike




> Bill Dube wrote:
> 
> > If you place the "dimples" on the car in the correct areas, it will
> > work much better than dimples all over.
> ...


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## EVDL List (Jul 27, 2007)

I've been soaking up all the excellent information here for over a year and
this topic actually falls within my area of expertise. So, at the risk of
getting too far off topic, just some quick trivia. The dimples on the golf
ball got their start way back when golfers noticed that their (Very
expensive) leather balls, stuffed with feathers, flew farther after they
became scuffed up a bit. The next generation of cheaper balls (Gutta-percha)
saw the use of grooves which lead to dimples. 
-- 
View this message in context: http://www.nabble.com/Mythbusters%3A-Golf-Ball-Effect-improves-aerodynamics-tp26013578p26018494.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

I just painted my Electercel and ended up with a bad case of orange
peel...So should I buff it out or leave it for the dimple effect 


Buddy Mills
[email protected]

Look mom, no gas. http://www.evalbum.com/2887

Disclaimer: No animals were harmed or killed in the process of writing this
email. Any stories to the contrary are, for the most part, either fictional
or greatly exaggerated. =




-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of SLPinfo.org
Sent: Thursday, October 22, 2009 12:58 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics

Hey folks,

Saw an episode of Mythbusters last night - they began by testing if a dirty
car gets better gas mileage than a clean car (based on the assumption of a
dirty car giving a "golf ball effect" - the dimples on a golf ball break up
the airflow and result in better aerodynamics). Well the dirty car got
poorer gas mileage so the initial myth was busted. BUT then they created a
car with a truly dimpled surface that looked a lot like that of a golf ball
(dimples enlarged to the scale of the car) and it improved gas mileage by
11% over a smooth surface on the same car. Here's a link:

http://dsc.discovery.com/videos/mythbusters-dirty-vs-clean-car/

For those who are perhaps up to custom designs, making body panels with a
dimpled surface could potentially improve range. Doing it on the sheet
metal of an existing car would be extremely difficult to do (as they
explained in the episode). They used a clay material added to the outside
of the car for the test.


- Peter FLipsen Jr
http://www.evalbum.com/1974
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## EVDL List (Jul 27, 2007)

Saw the same episode. Kind of ugly car with the dimple features - but it
does prove that smooth is not necessarily the most aerodynamically slick.


I was hoping for a test of the car w/ a supersized SPEEDO LZR RACER suit for
the car.



> SLPinfo.org <[email protected]> wrote:
> 
> > Hey folks,
> >
> ...


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## EVDL List (Jul 27, 2007)

Actually, it works for a very wide range of speeds.

You trip the boundary layer a bit early on purpose. At slower speeds, 
this is"'just in time" and at higher speeds it is a bit early, but no 
big deal. At very slow speeds, the aero drag is so small it hardly matters.

Bill Dube'

.

>I would guess that improves mileage Only at a particular speed or narrow
>speed range.
>And probably worsens it at speeds +/-10mph from that.

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## EVDL List (Jul 27, 2007)

I was thinking of making fiberglass "hubcaps" for my car, but very
flat and covering most of the wheel. (Brake cooling may suffer.) The
intention being to improve aerodynamics. If that worked, how about
dimpling the surface like a golf ball? Does the dimple size depend on
what speed you plan on averaging? The dimples on the Mythbusters car
were quite large compared to a golf balls dimples. Anyone know of any
dimple research projects?

Dave Cover

PS, Myers Motors used to dimple parts of their bodywork, seems to be
missing on the NMG2.



> Bill Dube <[email protected]> wrote:
> > Actually, it works for a very wide range of speeds.
> >
> > You trip the boundary layer a bit early on purpose. At slower speeds,
> ...


----------



## EVDL List (Jul 27, 2007)

No research is required or maybe on your car for placement of panels in the 
correct positions.

Many race cars use a exposed carbon fiber weave panels that is just clear 
coated over many different size weave patterns.

Look at the new ZR1 race Corvette, it has the expose carbon fiber weave just 
on the hard top which is use to reduce drag.

Roland


----- Original Message ----- 
From: "dave cover" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, October 23, 2009 4:41 AM
Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics


I was thinking of making fiberglass "hubcaps" for my car, but very
flat and covering most of the wheel. (Brake cooling may suffer.) The
intention being to improve aerodynamics. If that worked, how about
dimpling the surface like a golf ball? Does the dimple size depend on
what speed you plan on averaging? The dimples on the Mythbusters car
were quite large compared to a golf balls dimples. Anyone know of any
dimple research projects?

Dave Cover


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## EVDL List (Jul 27, 2007)

> Curtis Keller <[email protected]> wrote:
> > I was hoping for a test of the car w/ a supersized SPEEDO LZR RACER suit for
> > the car.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Started racing aluminum canoes in the early sixties. Believed that a good 
wax job would fill the porosity of the metal allowing a bit more speed. 
>From there we began to build our own wood fiberglass canoes and gave them a 
good waxing. Eventually moved on to silicon, believing it provided a bit 
more slip in the water. The current hulls are composite materials. Then we 
heard about the sailboat fellows trying a light sanding with wet/dry 
sandpaper. From there we heard that they were experimenting with a dimpled 
surface. The theory was that the water adhered to the surface allowing 
water to slip on water instead of water against the hull. These type of 
hulls were doing better over their competitors.. No idea what the current 
design for sailboat hulls use now.

Steve

----- Original Message ----- 
From: "Roland Wiench" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, October 23, 2009 10:24 AM
Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics


> No research is required or maybe on your car for placement of panels in 
> the correct positions.
>
> Many race cars use a exposed carbon fiber weave panels that is just clear 
> coated over many different size weave patterns.
>
> Look at the new ZR1 race Corvette, it has the expose carbon fiber weave 
> just on the hard top which is use to reduce drag.
>
> Roland
>
>
> ----- Original Message ----- 
> From: "dave cover" <[email protected]>
> To: "Electric Vehicle Discussion List" <[email protected]>
> Sent: Friday, October 23, 2009 4:41 AM
> Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>
>
> I was thinking of making fiberglass "hubcaps" for my car, but very
> flat and covering most of the wheel. (Brake cooling may suffer.) The
> intention being to improve aerodynamics. If that worked, how about
> dimpling the surface like a golf ball? Does the dimple size depend on
> what speed you plan on averaging? The dimples on the Mythbusters car
> were quite large compared to a golf balls dimples. Anyone know of any
> dimple research projects?
>
> Dave Cover
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> 

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## EVDL List (Jul 27, 2007)

So how would you apply this to a surface to maintain the correct
"roughness" and yet have a durable surface? If you applied it like
regular fiberglass, wouldn't you end up smoothing it out? Don't know
but I want to. Jerry?

Dave Cover



> Roland Wiench <[email protected]> wrote:
> > Here is a material at: http:www.uscomposites.com/carbonpage.html i=
> n a
> > certain weave size that is apply to race cars. NASCARs have this mater=
> ...


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## EVDL List (Jul 27, 2007)

> dale henderson wrote:
> > i assume the size of the dimples corresponds to a certain velocity wrt effientcy. so what if the dimples had a fractal pattern of larger and smaller holes?
> 
> A particular pattern can be optimized for the greatest improvement at a
> ...


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## EVDL List (Jul 27, 2007)

You first have to remove and paint from either a metal or any other surface 
which is done with a paint remover. Then the surface is rough up with a 18 
to 24 grit paper, where if you ran your fingers across this surface, it will 
cut you.

If the surface is metal, you spray a coat of epoxy primer that is mix with a 
epoxy primer at 200 percent. This is very thin which looks like black ink. 
This soaks deep into the metal which gives a surface that gives a good bond 
to the epoxy resin that is apply to this surface.

Next the carbon fiber is lay on this wet epoxy resin and roll with a rubber 
roller. I use the type of roller that is use wall covering. After apply 
this first step, the carbon fiber surface will still have a deep waffle 
pattern. You can either leave it black or you can spray another thin epoxy 
primer and leave it that way, or spray a clear and/or color coat.

This will still leave a waffle or other type of carbon fiber pattern to the 
surface. If you want to smooth this surface where the carbon fiber that 
does not show any weave, than you must add more epoxy resin to the surface, 
let dry until it's tacky and keep on applying more resin for two to three 
more coats.

Let the surface dry for at least 24 hours and start to color sand this 
surface until there is no more high and low areas on this surface. Apply a 
coat of epoxy of primer at 100 percent mix with thinner and color sand it 
after it dry for 24 hours. The shoot it with epoxy sealer, color sand, 
color coats, color sand, and then your clear coat.

It took me two years, and that's with a in house body man to reshape and 
refinish my EV.

Roland




----- Original Message ----- 
From: "dave cover" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, October 30, 2009 7:50 AM
Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics


So how would you apply this to a surface to maintain the correct
"roughness" and yet have a durable surface? If you applied it like
regular fiberglass, wouldn't you end up smoothing it out? Don't know
but I want to. Jerry?

Dave Cover



> Roland Wiench <[email protected]> wrote:
> > Here is a material at: http:www.uscomposites.com/carbonpage.html in a
> > certain weave size that is apply to race cars. NASCARs have this material
> > right behind the rear window. GT Group 7 cars will have the entire top
> ...


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## EVDL List (Jul 27, 2007)

The Corbin Sparrow, an electric three-wheeler alot of us remember, 
had dimples on the back side of the front fenders. The front part of 
the fenders remained smooth.

Check them out here:

http://upload.wikimedia.org/wikipedia/commons/0/0c/CorbinSparrow..jpg

Chip Gribben
NEDRA






> [email protected] wrote:
> 
> > ----- Original Message -----
> > From: "dale henderson" <[email protected]>
> ...


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## EVDL List (Jul 27, 2007)

Moon disks! Back to the 50s.



> dave cover <[email protected]> wrote:
> > I was thinking of making fiberglass "hubcaps" for my car, but very
> > flat and covering most of the wheel. (Brake cooling may suffer.) The
> > intention being to improve aerodynamics. If that worked, how about
> ...


----------



## EVDL List (Jul 27, 2007)

Has anyone sent pictures of the Sparrow and others back to Mythbusters?

The list might get some attention if we got mentioned on their site....

Bob Sisson
1993 Geo Metro Convertible Project
Gaithersburg MD

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## EVDL List (Jul 27, 2007)

I got flat stainless steel ones for my EV (mainly because I liked the looks -
they aren't going to improve the aerodynamics of a pick-up truck much!) :

http://www.jcwhitney.com/WHEEL_COVERS_RACING_DISC?ID=12;0;0;0;100001;ProductName;0;0;0;N;2003995;0;0




Moon disks! Back to the 50s.

-- 
View this message in context: http://old.nabble.com/Mythbusters%3A-Golf-Ball-Effect-improves-aerodynamics-tp26020851p26145997.html
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## EVDL List (Jul 27, 2007)

Nothing against Mythbusters, but here's another take on it, almost five
months ago:
http://watch.ctv.ca/daily-planet/season-14/daily-planet-june-09-2009/#clip181550
[video unfortunately cuts out after 5:11 mins...]

In particular, the product they were looking at is:
http://www.fastskinz.com/
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