# dimple/ripple cars ?



## dragonsgate (May 19, 2012)

marc1337 said:


> Hi, I joined the forum a couple years ago but I didn't have the ressources to build my own car. Now I would like to start a project and I remembered the mythbuster episode where they test the fuel economy of a car with dimple and results showing a fuel economy of 11%.
> 
> I read many controversial discussions on forums, some saying it wouldn't change much, some saying ripples might be better, I wanted to know your opinion on this. Would it make a noticeable difference on EV ?
> 
> thanks


I don’t remember what speeds they did the tests at but it was probably at or above the break speed of 50mph. Unless you are constantly driving the freeways it probably will not make much difference. In stop and go traffic your car will just look like an old beater. Get ready to hear “Hey dude! That’s some serious hail damage!” a lot. I don’t keep up with things much but I haven’t seen any of the racers doing it. I think Porsche was toying with the idea.


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## dougingraham (Jul 26, 2011)

marc1337 said:


> Hi, I joined the forum a couple years ago but I didn't have the ressources to build my own car. Now I would like to start a project and I remembered the mythbuster episode where they test the fuel economy of a car with dimple and results showing a fuel economy of 11%.


There had to be something wrong with the science or you would see cars and airplanes dimpled. The airlines would kill for an 11% increase.

Get your car on the road and then worry about adding dimples. There are so many other things that need to happen first. And air drag issues only matter at highway speeds. For the stop and go driver light weight would be far more important.


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## Siwastaja (Aug 1, 2012)

dougingraham said:


> There had to be something wrong with the science or you would see cars and airplanes dimpled. The airlines would kill for an 11% increase.


This is only my speculation, but the efficiency increase from dimpling may work best in shapes with large surface area up against the wind. That is, it works well for golf balls that have 1:1 "aspect ratio", and so-so for cars that are about triple the length of their width or height. But airplanes already have very thin and long profile so there would be little effect.

You also have to consider the increased complexity and cost in manufacturing, and possibly increased weight and outer measurements that eat away part of the gained effect.

Mythbusters test would probably have decreased fuel efficiency if they tested in city traffic or combined city/freeway due to their heavy clay setup. But they only wanted to test the aerodynamics and purposely ignored other factors.


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## marc1337 (Aug 11, 2009)

okay thank you, I guess since cars and plane already have a aerodnamic shape it doesn't really matter, the car they used was pretty large and old so maybe it wasn't very designed for aerodynamics. On a more recent car the energy economy would probably be a lot less.


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## Ziggythewiz (May 16, 2010)

Also if you plan to spin the car as often as you would a golf ball the dimples would probably help.


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## few2many (Jun 23, 2009)

At low speed, it will have higher drag. At high speed, supposed to have significantly lower drag. There is a company that makes a stylized vinyl wrap, that they claim simulates golf ball dimples. All independent tests reveal less efficiency.


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## TexasCotton (Sep 18, 2008)

I do not know about dimples IDK. However a really cool concept /idea for vehicles would be a airless tire design . I have seen images and youtube but not sure that the tire OEM ,s are in to mass market.


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## dougingraham (Jul 26, 2011)

TexasCotton said:


> I do not know about dimples IDK. However a really cool concept /idea for vehicles would be a airless tire design . I have seen images and youtube but not sure that the tire OEM ,s are in to mass market.


Bridgestone has this already. Here is a link to the first story that came up on a google search.

Tweel story link

It is more likely that they cost more than regular tires + wheels so the OEM's are reluctant to put them on cars even if there are large advantages.


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## TexasCotton (Sep 18, 2008)

Yea 
I think the youtube video was bridgestone. The adoption curve and DOT compliance would be a steep hill for this concept.


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## dragonsgate (May 19, 2012)

A rock in the tread can change the balance of the tire. Just imagine if a bunch of those holes got clogged with dirt or mud.


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