Dimples are not Zits

trikesrule · 2 Dec 2006, 06:10 (Ref:1779973)

See RCE Vol 16 #10 article on Dimples. What are your thoughts guys?.........trikes

**Peter Mallett** · 2 Dec 2006, 10:25 (Ref:1780201)

I haven't a clue what you are talking about.

trikesrule · 2 Dec 2006, 10:47 (Ref:1780211)

Hi Peter Racecar Engineering have an article about Dimple technology on surfaces. It's in the above mentioned Issue / Volume. Have u seen it? Am I in the correct section for posting this sort of thing......trikes

**Peter Mallett** · 2 Dec 2006, 10:52 (Ref:1780213)

Trikes,

You assume we are all able to obtain RCE, fyi I am in Moscow thus it's highly unlikely that I'll see it. So, if you want to discuss something you'll need to be more specific.

trikesrule · 2 Dec 2006, 11:30 (Ref:1780244)

Moscow wow. Umm My Gravity Racer(s) and my one of my Helmets have Dimples on them and in testing (and on race day) they have yielded quite a gain in speed. About two seasons back I made my boss a Dimpled nose cone for his Formula V. He went about 3/10+ quicker and he said there was less turbulence / buffeting with his Helmet. I'm just wondering if anyone else has tried Dimples.........trikes

Al Weyman · 2 Dec 2006, 12:26 (Ref:1780278)

Kirk Douglas would be on a winner then but only if he wore an open face job :-)

**Adam43** · 2 Dec 2006, 12:33 (Ref:1780280)

They are good on golf balls. I've not tried them on an XJS yet...

Quote:

Originally Posted by trikes

About two seasons back I made my boss a Dimpled nose cone for his Formula V. He went about 3/10+ quicker and he said there was less turbulence / buffeting with his Helmet.

So you are saying that there is a dimple/surface ratio that improves the CoD significantly to substatially reduce the time between the end and the start of the circuit by a significant percentage?
Or did he just drive quicker?

What were the two nose cones like?

JohnD · 2 Dec 2006, 12:42 (Ref:1780285)

Trikes,
Dimples are just one type of vortex generator, that may be used in aero work. The idea is that they disturb the boundary layer, just enough to bring some free flow inwards, speding flow near the surface and preventing the boundary getting thicker, a precursor to seperation and stalling. In a wing, stall destroys lift, on a car it induces turbulence and drag. (Google for "Vortex generator dimple" for lots of references)

So, Yes, dimples could reduce turbulence! But having seen your downhill racer, I have to say that as a smooth, aerodynamic, low drag teardrop shape, how can I tell you this - it's not! Big, big smiley!

Have you tried the time honoured, cheap and informative method of tufts? Short, 3-6" lengths of wool taped to the surface under question. Take photos at speed, and look for movement of the tufts.
Still tuft=laminar flow. (good!)
Fluttery tuft=turbulent. (bad!)

If tufts downstream from a new vortex generator have less flutter than before - Result!

John

johnw · 2 Dec 2006, 15:56 (Ref:1780369)

Quote:

Originally Posted by Al Weyman

Kirk Douglas would be on a winner then but only if he wore an open face job :-)

norman-normal · 2 Dec 2006, 16:43 (Ref:1780393)

This technology has ben used for two decades, at least, for military jets (the painted surface has a texture similar to a fine grade of sand paper).

Fear of sponsor complaints, is the only logical reason it isn't used on race cars.

JohnD · 2 Dec 2006, 17:06 (Ref:1780396)

Quote: "a fine grade of sand paper"

ironic really, in view of Trikes' parallel thread on Waxes and ultra high polish!

And as shark skin contains vortex generators, this technology has been used for 400 million years (approximately!).
See: http://www.astrographics.com/Gallery...ex/GP2127.html

John

**Tim Falce** · 2 Dec 2006, 17:38 (Ref:1780409)

Quote:

Originally Posted by trikesrule

Moscow wow. Umm My Gravity Racer(s) and my one of my Helmets have Dimples on them and in testing (and on race day) they have yielded quite a gain in speed. About two seasons back I made my boss a Dimpled nose cone for his Formula V. He went about 3/10+ quicker and he said there was less turbulence / buffeting with his Helmet. I'm just wondering if anyone else has tried Dimples.........trikes

Could you say that he is that consistent that 3/10th could be down to dimples or was the weather kinder/he drove better or even had different tyre pressures on the day?
I have lots of dimples on my bonnet and helmet from stone chips and they make no difference at all.

terence · 2 Dec 2006, 17:54 (Ref:1780423)

Quote:

Originally Posted by norman-normal

This technology has ben used for two decades, at least, for military jets (the painted surface has a texture similar to a fine grade of sand paper).

Fear of sponsor complaints, is the only logical reason it isn't used on race cars.

Just like pebble dashing then,must get the House done!

terence · 2 Dec 2006, 17:55 (Ref:1780425)

Quote:

Originally Posted by falcemob

Could you say that he is that consistent that 3/10th could be down to dimples or was the weather kinder/he drove better or even had different tyre pressures on the day?
I have lots of dimples on my bonnet and helmet from stone chips and they make no difference at all.

How do you know??

terence · 2 Dec 2006, 17:58 (Ref:1780426)

I wonder if any Helmet manufactureras have thought of this,a giant golf ball with a slot to see out of .

trikesrule · 2 Dec 2006, 22:52 (Ref:1780546)

Hi Guys. For my boss's Formula Vee I flopped a copy of his old nose cone then added dimples in the hi-pressure areas. On race day he had Practise + five races and alternated between nose cones. At the days conclusion he sat down and added up the lap times for each three events. Hence two years later he's still using the dimpled cone. Now u and I know there are flaws in his process but he's a hard man to convince or change anything at all. He got curious when he heard how much T/D and more speed the Gravity club members found. That Denticle site is interesting to me. My other Racer has Vortex Generators on top and at the rear of it's wheel covers. They are worth .7kmh. Not much I know but all these little gains add up and could part explain why it's never lost a race and holds every speed record at every track it's been too in Australia. I put Zymol on my racer and yellow helmet and found another 1 kmh. I'm not a rocket scientist. if it makes my racers go faster it stays on. If not......... A giant golf ball with a slot for a helmet - not as silly as it sounds. Actually my yellow helmet has that technology on it. The stone chips on the front of a car when compared to my helmet are probably to small and not placed in the right pattern............trikes

retro_msport · 5 Dec 2006, 13:35 (Ref:1782544)

Quote:

Originally Posted by terence bower

I wonder if any Helmet manufactureras have thought of this,a giant golf ball with a slot to see out of .

So thats why golf balls have dimples ....

ss_collins · 5 Dec 2006, 13:56 (Ref:1782557)

Peter you can get RCE in Moscow - on subscription...

anyway the issue in question is October 2006 - Jan 2007 is about to hit the shelves. However I'm very interested to see some pics of Trikes Dimpled Vee nose - I'd love to find out if it works on a Sheane mk2...

Certainly dimples are an area not fully exploited by motorsport as yet, the shape of the dimple its pretty critical though I don't think that random stone chips would help

trikesrule · 6 Dec 2006, 07:55 (Ref:1783082)

SS It will take me a couple of days to get a pic. My Boss is thinking of selling his v and going to F2 or F3 here in aus. I spoke with Pete today about those dimples and he said he is 250 rpm more at the end of Symonds Plains back straight (about 1 km) and it's the difference between getting a tow from the quicks whereas before he said he just couldn't quite get onto the back of them (theres two blokes who are always out front).........trikes

**dtype38** · 6 Dec 2006, 20:33 (Ref:1783569)

I just had a look at some golf balls, and curiously they don't all have the same dimple pattern. Most are regular, although they vary in depth and sharpness of edge, but one make actually has different sizes of dimples arranged in an apparently random fashion. Seems there isn't only one solution even for a shape as simple as a sphere!

ss_collins · 9 Dec 2006, 10:59 (Ref:1785776)

the dimple shape and pattern is crucial.

Trikes I can wait but I'm really keen to see