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[EVDL] Mythbusters: Golf Ball Effect improves aerodynamics

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#1 ·
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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#2 ·
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,
>
> 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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>

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#3 ·
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" <xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
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
> -------------- next part --------------
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> =


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#4 ·
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 <xxx@xxx.xxx> wrote:
> Hey folks,
>
> Saw an episode of Mythbusters last night - they began by testing if a dir=
ty
> 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 creat=
ed a
> car with a truly dimpled surface that looked a lot like that of a golf ba=
ll
> (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 outs=
ide
> of the car for the test.
>
>
> - Peter FLipsen Jr
> http://www.evalbum.com/1974
> -------------- next part --------------
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> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
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>
>



-- =

www.electric-lemon.com

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#5 ·
Wow, thanks Bill, that's an eye opener. Very interesting.
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#6 ·
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
> 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.

You need to understand what the dimples do, and why they work. You can't
just blithely apply them any old way and expect good results.

The dimples need to be placed just behind the widest cross-section of
the object, right at the point where the laminar airflow would have
detached and become turbulent. By triggering lots of small points of
turbulence, you avoid creating a much larger turbulence.

A golf ball has dimples everywhere because it rotates. If you prevent it
from rotating (gyroscope inside, etc.) then adding dimples just behind
the widest point reduces the drag by the largest amount.

Since it spins, they have to put dimples everywhere. The dimples on the
front and back surfaces *add* drag. But it turns out that they add less
drag than the dimples around the widest point remove; so you come out ahead.

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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#7 ·
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 <xxx@xxx.xxx> wrote:

> 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
> > 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.
>
> You need to understand what the dimples do, and why they work. You can't
> just blithely apply them any old way and expect good results.
>
> The dimples need to be placed just behind the widest cross-section of
> the object, right at the point where the laminar airflow would have
> detached and become turbulent. By triggering lots of small points of
> turbulence, you avoid creating a much larger turbulence.
>
> A golf ball has dimples everywhere because it rotates. If you prevent it
> from rotating (gyroscope inside, etc.) then adding dimples just behind
> the widest point reduces the drag by the largest amount.
>
> Since it spins, they have to put dimples everywhere. The dimples on the
> front and back surfaces *add* drag. But it turns out that they add less
> drag than the dimples around the widest point remove; so you come out
> ahead.
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
> _______________________________________________
> 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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#8 ·
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.
>
> A golf ball has no front or back so you have to put the dimples
> everywhere so there will be dimples in the area that you actually need
> them to be.
>
> With a car, you always travel in the same orientation, so you can put
> the dimples where they help most, and not put dimples where they would
> work against you.
>
> They way they do this on gliders (and other aircraft) is to put drops
> of used gear oil (cheapest, but you can use expensive colored fluids)
> on the clean surface of the wings and body in the areas you guess will
> go turbulent. (Like about 1/3 to 1/2 way along the chord of the wing.)
> You then take the airplane for a flight. The oil drops turn into
> streaks. Where the streaks go from a straight line to "mush" is where
> you want to put a boundary layer "trip", (like a row of dimples.)
>
> You actually want to place the trip just a bit ahead of the "mush".
> They typically use a thick rough "vortex generator" tape to do this on
> gliders.
>
> Picture and simple article:
> http://www.deturbulator.org/Progress-OilFlows.asp
>
> Here is a discussion thread showing the tape and the results:
>
> http://ecomodder.com/forum/showthread.php/belly-pan-vortex-generators-1209-4.html
>
> Complicated article:
> http://en.wikipedia.org/wiki/Boundary_layer
>
> Bill Dube'
>
>
>
>

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#9 ·
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
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#10 ·
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
xxx@xxx.xxx

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: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] 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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#11 ·
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 <xxx@xxx.xxx> wrote:

> 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/
>
>


--
Curtis Keller
keller.xxx@xxx.xxx
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#12 ·
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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#13 ·
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 <xxx@xxx.xxx> wrote:
> 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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>
>



--
http://www.evalbum.com/2149

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#14 ·
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" <xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
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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#15 ·
Curtis Keller <keller.xxx@xxx.xxx> wrote:
> I was hoping for a test of the car w/ a supersized SPEEDO LZR RACER suit for
> the car.

Indeed, that would be supremely awesome! :D


-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555

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#16 ·
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" <xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
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" <xxx@xxx.xxx>
> To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
> 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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#17 ·
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 <xxx@xxx.xxx> 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=
ial
> right behind the rear window. GT Group 7 cars will have the entire top
> cover with this material which is just clear coated.
>
> Jet fighters may have the under surfaces of the rear elevators made out of
> this material which is only coated with a de-gloss resin.
>
> The size of the carbon fiber looks like in the 17 oz size.
>
> Roland
>
>
>
>
>
>
> ----- Original Message -----
> From: "dale henderson" <xxx@xxx.xxx>
> To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
> Sent: Thursday, October 29, 2009 10:55 PM
> Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>
>
> 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?
>
> harry
>
> Albuquerque, NM
> current bike: http://www.austinev.org/evalbum/1179
> current non-bike: http://evalbum.com/1581
>
>
> --- On Thu, 10/22/09, Jeff Shanab <xxx@xxx.xxx> wrote:
>
>> From: Jeff Shanab <xxx@xxx.xxx>
>> Subject: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>> To: xxx@xxx.xxx.edu
>> Date: Thursday, October 22, 2009, 10:39 PM
>> >
>> > 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.
>>
>> I would guess that improves mileage Only at a particular
>> speed or narrow
>> speed range.
>> And probably worsens it at speeds +/-10mph from that.
>>
>> In our fluids class they showed an experiment that used a
>> blower box
>> with two round holes and suspended above this was a balance
>> beam where
>> you could put two shapes
>> You also could introduce smoke tracers at the center of the
>> airflow for
>> each air stream.
>> One of the tests had two identical lacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynamically equivalent,
>> they took
>> one ball and scratched it at regular intervals with a
>> scratch awl.
>> At low speeds the scratches made horrific added drag. As
>> speed was
>> increased, there was a point where the scale shifted and
>> the drag was
>> considerably less than the smooth ball. Then it went back
>> to being worse
>> again.
>>
>> The smoke revealed what happened. The air separated at the
>> rear of both
>> spheres causing most the drag at higher speeds.
>> The scratches did 2 things. They filled with little rolling
>> tufts of air
>> like ball bearings and they also created little low
>> pressure areas
>> behind that caused the airstream to curve with the back
>> side of the ball
>> and reduce the separation.
>>
>>
>> _______________________________________________
>> 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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>
> _______________________________________________
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>
>



-- =

http://www.evalbum.com/2149

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#18 ·
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
certain speed. If you always cruise at 70 mph, then optimize the pattern
for that speed.

If you "spread out" the pattern, you get less improvement at that
certain speed, but some improvement at other speeds.

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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#19 ·
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" <xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
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 <xxx@xxx.xxx> 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
> cover with this material which is just clear coated.
>
> Jet fighters may have the under surfaces of the rear elevators made out of
> this material which is only coated with a de-gloss resin.
>
> The size of the carbon fiber looks like in the 17 oz size.
>
> Roland
>
>
>
>
>
>
> ----- Original Message -----
> From: "dale henderson" <xxx@xxx.xxx>
> To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
> Sent: Thursday, October 29, 2009 10:55 PM
> Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>
>
> 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?
>
> harry
>
> Albuquerque, NM
> current bike: http://www.austinev.org/evalbum/1179
> current non-bike: http://evalbum.com/1581
>
>
> --- On Thu, 10/22/09, Jeff Shanab <xxx@xxx.xxx> wrote:
>
>> From: Jeff Shanab <xxx@xxx.xxx>
>> Subject: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>> To: xxx@xxx.xxx.edu
>> Date: Thursday, October 22, 2009, 10:39 PM
>> >
>> > 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.
>>
>> I would guess that improves mileage Only at a particular
>> speed or narrow
>> speed range.
>> And probably worsens it at speeds +/-10mph from that.
>>
>> In our fluids class they showed an experiment that used a
>> blower box
>> with two round holes and suspended above this was a balance
>> beam where
>> you could put two shapes
>> You also could introduce smoke tracers at the center of the
>> airflow for
>> each air stream.
>> One of the tests had two identical lacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynamically equivalent,
>> they took
>> one ball and scratched it at regular intervals with a
>> scratch awl.
>> At low speeds the scratches made horrific added drag. As
>> speed was
>> increased, there was a point where the scale shifted and
>> the drag was
>> considerably less than the smooth ball. Then it went back
>> to being worse
>> again.
>>
>> The smoke revealed what happened. The air separated at the
>> rear of both
>> spheres causing most the drag at higher speeds.
>> The scratches did 2 things. They filled with little rolling
>> tufts of air
>> like ball bearings and they also created little low
>> pressure areas
>> behind that caused the airstream to curve with the back
>> side of the ball
>> and reduce the separation.
>>
>>
>> _______________________________________________
>> 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
>>
>>
>
>
>
>
> _______________________________________________
> 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
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
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> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>



--
http://www.evalbum.com/2149

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#20 ·
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




xxx@xxx.xxx.edu wrote:

> ----- Original Message -----
> From: "dale henderson" <xxx@xxx.xxx>
> To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
> Sent: Thursday, October 29, 2009 10:55 PM
> Subject: Re: [EVDL] Mythbusters: Golf Ball Effect improves
> aerodynamics
>
>
> 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?
>
> harry
>
> Albuquerque, NM
> current bike: http://www.austinev.org/evalbum/1179
> current non-bike: http://evalbum.com/1581
>
>
> --- On Thu, 10/22/09, Jeff Shanab <xxx@xxx.xxx> wrote:
>
>> From: Jeff Shanab <xxx@xxx.xxx>
>> Subject: [EVDL] Mythbusters: Golf Ball Effect improves aerodynamics
>> To: xxx@xxx.xxx.edu
>> Date: Thursday, October 22, 2009, 10:39 PM
>>>
>>> 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.
>>
>> I would guess that improves mileage Only at a particular
>> speed or narrow
>> speed range.
>> And probably worsens it at speeds +/-10mph from that.
>>
>> In our fluids class they showed an experiment that used a
>> blower box
>> with two round holes and suspended above this was a balance
>> beam where
>> you could put two shapes
>> You also could introduce smoke tracers at the center of the
>> airflow for
>> each air stream.
>> One of the tests had two identical lacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynamically equivalent,
>> they took
>> one ball and scratched it at regular intervals with a
>> scratch awl.
>> At low speeds the scratches made horrific added drag. As
>> speed was
>> increased, there was a point where the scale shifted and
>> the drag was
>> considerably less than the smooth ball. Then it went back
>> to being worse
>> again.
>>
>> The smoke revealed what happened. The air separated at the
>> rear of both
>> spheres causing most the drag at higher speeds.
>> The scratches did 2 things. They filled with little rolling
>> tufts of air
>> like ball bearings and they also created little low
>> pressure areas
>> behind that caused the airstream to curve with the back
>> side of the ball
>> and reduce the separation.
>>
>>
>> _______________________________________________
>> 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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#21 ·
Moon disks! Back to the 50s.

dave cover <xxx@xxx.xxx> 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
> 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.
>
> On Fri, Oct 23, 2009 at 1:23 AM, Bill Dube <xxx@xxx.xxx> wrote:
>> 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.
>>
>> _______________________________________________
>> 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
>>
>>
>
>
>
> --
> http://www.evalbum.com/2149
>
> _______________________________________________
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>
>



--
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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#22 ·
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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#23 ·
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
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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#24 ·
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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