Golf Ball Aerodynamics

Carbon · Post 06 Sep 2006, 15:05

A question for the aero engineers on this great site. I am having a discussion with a mate about golf ball aerodynamics, and the use of dimples on the surface of the balls.

Can someone explain the effect the dimples have on the ball? Are they for spin, curve, distance, lift or something completely different? If you could support your explaination with a mathematical model, it would mean a beer for me

I love this site. Cheers!

NickT · Post 06 Sep 2006, 15:12

Found this one that explains what is going on. Check out the section headed "The Dimples"

http://www.fi.edu/wright/again/wings.av ... lf-01.html

Found this one to, which is more indepth

http://www.aerospaceweb.org/question/ae ... 0215.shtml

manchild · Post 06 Sep 2006, 16:10

Already discussed here on several occasions

viewtopic.php?t=881&highlight=dimples

viewtopic.php?t=1104&highlight=dimples

viewtopic.php?t=414&highlight=dimples

viewtopic.php?t=671&highlight=dimples

NickT · Post 07 Sep 2006, 12:58

Manchild you must have the memory of an elephant

It never ceases to amaze me how you find these things

Carbon · Post 08 Sep 2006, 18:00

Thanks Gents, very helpful!

ss_collins · Post 01 Nov 2006, 12:22

There are some who believe dimples surfaces on a racecar can lower drag, wind tunnel figures on turning shafts seem to prove this. See Racecar Engineering V16N10 (with the new champ car on the cover)

pyry · Post 01 Nov 2006, 19:08

NickT wrote:Manchild you must have the memory of an elephant It never ceases to amaze me how you find these things

search.php

f1.redbaron · Post 02 Nov 2006, 17:56

pyry wrote:
NickT wrote:Manchild you must have the memory of an elephant It never ceases to amaze me how you find these things
search.php

yeah, but I don't think that he uses the search engine everytime some new topic pops-up.

Manchild, since the room in my memory is reaching critical levels, can I borrow some of your memory! I need it for my mid-terms!

Rob W · Post 03 Nov 2006, 01:36

I just went through and read the entire article about the golf-ball, and the follow-on articles about aerodynamics in aircraft etc.. Very interesting reading.

Cheers,

Rob W

kilcoo316 · Post 08 Nov 2006, 19:25

ss_collins wrote:There are some who believe dimples surfaces on a racecar can lower drag, wind tunnel figures on turning shafts seem to prove this. See Racecar Engineering V16N10 (with the new champ car on the cover)

I know Renault have had it looked at in the past with vortex generators on the rear wing, and it did work (quite well from what I'm told), I don't think they used it though - dunno why.

kimi_khodr_raikkonen · Post 08 Nov 2006, 20:58

lol tnx everyday new infos tnx alot

Kimi Iceman · Post 13 Jan 2007, 20:18

I was able to talk to Geoff Willis, former Honda "chassis-brain", when I was at the test before the Monza GP in 2005.

We discussed several things, including the dipples.
I asked him if they every tried out surfaces with dipples, just like a golf ball.
He answered yes, but this effect only appears on very small parts, like suspension. When I asked him why they didn't use it then, he said he's now allowed to talk about that.

This was very interresting though. So the F1 teams already tested this surfaces but none of them is using them on the cars.

But I remember the McLaren from 1998, he had a special "skin" at the lower end of the bargeboads, it was clearly visible. Perhaps I'll find a pic of it.

BreezyRacer · Post 14 Jan 2007, 00:46

The dimple effect really can be very subtle surface irregularies, it doesn't have to look like a dimple to be effective. I've heard of some aero engineers using fine sandpaper to test the effect.

3M made, for a short while VG tape which had extremely fine grooves (like a phono album) perpendicular to the flow. They claimed it reduced stall speeds on aircraft. Guess there was no market so it died.

Also if you search on the web you can find special outfits for skaters that have VG strips to reduce turbulance, especially around the thighs and shins. I think they were banned at the Olympics one yaer .. not really sure though.

In short, a surface that's too smooth builds a boundary layer much more than a rough one. When you're at a race it might be interesting to see where the shiney surfaces are and "flat" looking surfaces are. Often undertrays aren't shiney smooth but that might have more to do with the fab techniques than anything else.

Ray · Post 14 Jan 2007, 07:30

Richard Petty pulled a 'fast' one years ago with dimples. His team put dimples on the hood, and the roof too I think, to fool the tech inspectors. They spent so much time trying to figure out if it really did help, they didn't check the rest of the car. The engine was wildly illegal but they didn't catch it till it was too late. Can't remember if the cubic inches was illegal, or if it was just illegal in every respect.

Not sure if it helps having dimples, but I would guess it doesn't really hurt either. Golf balls go further with them, so it must have some merits.

RACKITUP · Post 14 Jan 2007, 11:41

BreezyRacer wrote:The dimple effect really can be very subtle surface irregularies, it doesn't have to look like a dimple to be effective. I've heard of some aero engineers using fine sandpaper to test the effect.

3M made, for a short while VG tape which had extremely fine grooves (like a phono album) perpendicular to the flow. They claimed it reduced stall speeds on aircraft. Guess there was no market so it died.

That sounds like you are describing riblets. 3M researched with riblets which were parallel to the flow. They reduced drag by about 3-7%, but have yet to be implemented because fuel prices aren't THAT high yet.

Studies have been conducted on dolphins, because in theory, they shouldn't be able to swim as fast as they actually can, until they looked closely at the skin and noticed strange patterns; riblets. Barracuda's release polymers along their skin that reduces drag by as much as 40%

Sorry I started to go off at a tanget