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Old 03-30-2010, 11:00 AM   #21 (permalink)
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I don't know if you're being serious and I have no idea what a flow test involves. I have an engine that I spent way too much money on, and when I asked the mechanic if he was going to polish the ports till they were mirror-like he said, "not quite that shiny, you want a little swirl as the mixture flows" or something like that. This is the theory behind the various rip-off devices you used to be able to put in your intake somewhere to "boost milage by XX %". 10 percent seems significant to me, wouldn't it increase milage a bit?

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Old 03-30-2010, 02:23 PM   #22 (permalink)
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How about those cycling helmets that have the dimples, anyone have any first hand knowledge on how they work?

Brian

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Old 03-31-2010, 08:23 PM   #23 (permalink)
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first hand? no, but obviously...you know what I would say..it works b/c of the turbulent effect...right?

Quote:
the turbulent boundary layer is able to remain attached to the surface of the ball much longer than a laminar boundary and so creates a narrower, low pressure, wake and hence less pressure drag. The reduction in pressure drag causes the ball to travel further.
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No. They only proved that 100 lb of extra weight has minimal effect on a car already in motion. They deliberately (and rightly, for the experiment) ignored the fuel used to accelerate the extra mass.
Correct.

The heavier car got a little bit better mileage b/c of the momentum of extra weight...but the v6 on the Taurus', acceleration would not be effected by the weight..

thanks for the useful info, all youze...I know its real...haha

bTW, if the thing improves the mileage, but it costs money, doesn't actually mean it's useless...b/c it could also be improving the resistance to wear and tear, right?

)**most things aren't practical for any and everybody...but they would be nice, and would be helping
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Old 03-31-2010, 11:07 PM   #24 (permalink)
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The dimples on golf balls were discovered almost by accident about 200 years ago. Smooth golf balls fly erratically, something you will see on the driving range when they get worn down.

The first golf balls were like little baseballs and very time consuming to produce ( called featheries) they were very similar in construction to tiny baseballs but packed with feathers, with a leather cover stitched together.

Then they started casting them out of gutta percha, a primitive type of plastic. At first they were smooth, but it was soon discovered that when the surface got scratched up they were more controllable, so they eventually became dimpled as the were cast.

The spin imparted to a golf ball and the dimples create pressure areas below in front and behind at the top of the ball. When the axis of that spin is truly horizontal the flight of the golf ball is perfectly straight on a windless day. When the axes is tilted relative to the ground the ball will turn, in flight, in the direction of the lower side of the axis. This is a slice or a hook depending on the angle of the axis.

I wonder if anyone here has measured the fuel economy of their car after it was nailed in a hail storm, which would (under certain circumstances) create a consistent dimpling of the surface of the sheet metal, at least on the top of the vehicle.

The turbulent wake behind smooth round or tubular object oscillates behind the object and creates more drag than the same wake when it is disturbed by dimpling.

I remember the skin of most sharks is so rough it will literally shred your flesh if you rub up against them.

Another thing to consider is the steps in a planing hull that reduce the surface friction in high speed watercraft.

Not my specialty (aerodynamics) so don't be too hard on my statements if they contain significant flaws.

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Mech
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Old 04-01-2010, 10:22 AM   #25 (permalink)
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New VW Golf and Polo have underbody panel with "golfball efect" ...
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Old 04-01-2010, 12:26 PM   #26 (permalink)
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Quote:
Originally Posted by IRONICK View Post
New VW Golf and Polo have underbody panel with "golfball efect" ...

Got pics? I've had no luck on Google.

How big dimples? How far apart?

In other words, ~3" wide X ~1/2" deep dimples like on Mythbusters car, or tiny ones like on a regular golf ball?
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Old 04-01-2010, 07:52 PM   #27 (permalink)
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Dimples probably need to be as uniform as possible, perhaps made out of bamboo?

...actually if one has those particular resources...could prolly DIY-it, into something functional..

I dunno, about the size...i would bet, bigger...b/c of the size of the object...not sure either..
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Old 04-01-2010, 09:19 PM   #28 (permalink)
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Quote:
Originally Posted by eqmos View Post
here, I'm not going to rehash all this...

MYTHBUSTERS prove golf ball dimple theory on cars works!!!
I don't think they proved anything of the sort. Please read this thread to understand why you should be skeptical of the results of that particular experiment: http://ecomodder.com/forum/showthrea...oct-10658.html
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Old 04-01-2010, 11:30 PM   #29 (permalink)
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Quote:
Originally Posted by aerohead View Post
I would respectfully recommend that you take a look at 'Boundary Layer Theory' by Schlichting.There is extremely solid science which disputes the physical possibility of dimples ever improving the airflow over an automobile.
+1

I do not even understand where the concept comes from. It makes no sense what so ever. As smooth as our eyes can see...it is still a golf ball micronically. Dispersing frictions, needs the golf ball...but as smooth as we can get it...right down to micronic bumps...increasing every bit of surface to have a function evenly...this equals tight boundaries, less friction..so very simple.

get it?
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Old 04-02-2010, 03:54 PM   #30 (permalink)
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it was also about the "hail damaged" car gets better gas mileage...

I have not read, anywhere that turbulent waves cannot be on a vehicle w/dimples...if you understand what I am saying....worded weird..

I cannot question, scientific process... when i saw it take place....w/positive results...there is no other explanation...if there is...then they would be required to apologize on national television...B/c they have millions of viewers.....and since auto-makers are implementing this, already...And I know they aren't just doing it for the novelty..

___Mythbusters themselves, were like, it's kinda' ugly...that was the only question, left open..

Ok, MetroMPG, thanks for the link...i'm collecting phrasings
Quote:
Originally Posted by wyatt
it works on a golf ball is because the golf ball spins in the air and is not stabilized.
its just a different shape...a car is not any more stabilized..."not stabilized"---what is 'stabilized' object?... the greater portion of a car is above ground level...so is suspended in air, by 4 tires...still, the body travels via air...so the car, is in the same realm of unstabilized object.....

the Great Pyramids of Egypt...are stable, then?....or the Statue of Liberty, or Gateway Arch, is stablized....

The dimples make (at least round like) objects, traveling through air, more stable..

If it counts, the '98 Taurus, was my first car.


K

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