Landracing Forum
Tech Information => Technical Discussion => Topic started by: oz on March 10, 2008, 05:01:36 AM
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A Golf Ball travels further than an equivelent ball of the same construction and size because of the dimples sticking the air to the surface of the ball,although difficult to reproduce the same kind of dimple over a large area would this work on fairings/streamlining/frame surface preperations as in rippled paint finishes?
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i think the dimples in a golf ball work because of the backward spin --you would get pretty dizzy if your car did that willie buchta
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We actually talked one time about building a body that had a golf ball surface all over it. Our first thought was several ball peen hammers. Then maybe a golf ball manufacturer could make us a cover for the body. We finally gave up. I still think that it would work. Brian #7796
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Here's another one of those subjects that comes up every year or two on landracing.com. Six or seven years ago Vetter had a bike at Bonneville with dimples all over the rear of the fairing -- might have been on the front, too, but I don't remember. No, I don't have any data nor run speeds -- but I remember seeing the odd appearance and paying enough attention to bring it to mind when I read these posts. Maybe someone else has more information.
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We actually talked one time about building a body that had a golf ball surface all over it. Our first thought was several ball peen hammers. Then maybe a golf ball manufacturer could make us a cover for the body. We finally gave up. I still think that it would work. Brian #7796
That was my idea!!!
here from the DLRA message board when somebody offerd up a Ford sedan body with hail damage for sale I give you the Dr Goggles Dimple-o-matic car treatment.....
Lynchy wrote:
Here's a question for the Aero literati:
Will the hail damage act the same as the dimpling on a golf ball and promote the laminar adhesion of air over the body thereby allowing an increased speed?
Is this cheating or Act of God?
Lynchy
Dunno Lynchy but I'm gonna bring a little ball-pein hammer to the lake next year in case it catches on , I hereby offer my services to "aero-dimple" any car for a cold six pack :evil:.
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Surely Jack has built a golf-ball body and had it rolled down his famous hill. :mrgreen:
Mike
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Look at this stuff, somewhat the same principal and no you down want dimples on the front.........
Wings and Wheels ...............
http://www.wingsandwheels.com/page29.htm
.................... Sealing Tapes and Control Seals along with Zig-Zag Turbulator and Dimple Turbulator Tapes (also called trip tapes -- "they create a rough place for the laminar flow to "trip over" into minor turbulence before separation occurs due to body shape. This reduces drag because this turbulence keeps the flowing air closer to the body than if it wasn't there, therefore reducing profile drag.", the Rev. H+.
Also here................
http://purplesagetradingpost.com/sumner/bvillecar/bvillelinks.htm
.................I have a lot of aero links under "Aerodynamic Info and LSR Calculator/Spread Sheet Sites",
Sum
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Seek out riblets:
http://aerodyn.org/Drag/riblets.html
http://home1.gte.net/pjbemail/RibletFlow.html
http://books.google.com/books?id=N4iZCl7dtO0C&pg=PA281&dq=riblet+film&sig=oqsz_60c8lRuH-mRiDTsZDHSly8 (page 281)
I am currently experimenting with riblets for the "future" project.
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Surely Jack has built a golf-ball body and had it rolled down his famous hill. :mrgreen:
Mike
Ifnitain't ona glider plane, I don't want one.
My "World Speed Record" for a bowling ball down the face of Hoover Dam from 66 is still good, in part because of the newly added security. 8-)
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I seem to be testing the "dimple theory". Every year new dents are appearing on my Stude's body, and I am also trying the "reverse dimple theory" where the rust is bulging the paint out.......... :-(
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Slim, it was "Corbin"
kent
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if you are constantly running 1 mph off of a record and exhausted all of the HP you have ... "THEN" start looking at this voodoo.... design and build your body "correctly" in the first place... all that crap works in theory and in wind tunnels but fails to deliver in the real world.... to add some dolaneese.... "a fool and his money are soon parted"
kent
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so thats why Dolan showed up at the NW Reunion sans tux and shoes.............. :-D
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i am running naked but have seen a nice rippled paint finish for the frame just thought i would run it by you guys if anyone has any tips on voodoo i am willing to learn that too amazing how much i have learned from this site already maybe thats one for another topic !
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Bonneville doesn't have a putting green, it's a putting white and you need orange balls or you loose them and there would be balls everywhere. This subject has been discussed before under the DIMPLE theory..
It's somewhere in the archives. :-o
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so thats why Dolan showed up at the NW Reunion sans tux and shoes.............. :-D
I made more money with no shoes, the halter top, and the tats.
OBTW: There is hope for Kent and I have decided to let him live. :-D
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excellent now thats funny orange balls it is best set up at the bend in the road we dont want to damage the course.
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Yeah, Corbin. That's what I meant. Who got into the post and switched what I said from Corbin to Vetter? Damn vandals are at it again.
Thanks, Kent.
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Can't resist throwing in my 2 cents on this one. Creative; maybe whacky; don't really expect anyone to do this; but..............
Make a steel roller for your wheeling machine with dimples. After you machine and heat treat it carefully layout and mark the pattern of dimples on the roller surface and mark them with dots of resist paint. Then acid etch the steel away to a depth of 20-30 thou. Build a bottom roller of steel with a thin hard rubber tread. Prototype dies to test the process can be just made of flat steel and tested in your hydraulic press that you put a pressure gauge on. Figure out the best diameter depth and spacing of the dimples, how to etch them and what thickness, durometer and adhesive to use for the lower roller. That way you won't go broke buying tool steel for the rollers to experiment with.
Now you can roll your pattern into the aluminum sheets for the top, side and belly pan panels. Then when you're all done and decide whether or not it makes the car go faster just think ------- what a neat way to make non skid panels for your flooring (another useless idea)
Ed Weldon
Los Gatos (on the far side of the mountain), CA
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hey ed willie here wernt you the inventer of the solor powered flashlight opps here come the forum cops willie buchta
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gee...... I thought the dimples in a golf ball were there to help keep it aloft............ so it could fly farther.......... hmmm :wink:
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Dimples have been in practice on golf balls since the 1930’s when research showed that they will help increase lift and reduce drag, but have yet to transfer to the racing world. Ferrari F1 tested dimples in a wind tunnel but didn’t go beyond that. Most likely the rules guys stopped it.
There has been some research in the Texas A&M low speed wind tunnel on wheel disks with dimples, which showed very good Reynolds numbers compared to non-dimpled wheel disks. They concluded any where from hexagons to icosahedral (20 sided) shapes worked well as the corners that trip the airflow to create the effect. The drag reduction and wake reduction was considerable also. But the practical side, it is very expensive and difficult to make multi sided dimples.
There is a Lexis that comes with dimples on the floor to reduce noise. Is this reducing noise by reducing drag? Is this why the intake ports in a head are a little rough vs very smooth? There is a pretty good article in Race Car Engineering Oct. 2006 on this subject.
Just food for thought and something to consider.
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Guys and Gals.
I have tested the theory of dimples many times,when panels or other parts that I build havent fit,I have put many "ballpien dimples" and thrown them,doesnt seem to fly any further than peices without dimples. :-D :-D Didnt know I was doing R&D until just now.
Phil.
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Not important to the topic probably, but my dad had Goff balls that had little SQUARES all over them (from the late '30s/early '40s).
Remember the flight of the golf ball - it tumbles over and over and over- might not be too desireable with yer racer!
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I seem to remember Richard Petty running a dimpled vinyl top on his '68 Plymouth. Didn't seem to help him much, other than to psych out the other drivers.
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The old saying down south about Richard Petty was, "If Richard won a race dragging a dead cow behind his car there wouldn't a cow in the county come the next race!".
He did a lot of head work on his competitors.
Rex
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Look at this stuff, somewhat the same principal and no you down want dimples on the front.........
Wings and Wheels ...............
http://www.wingsandwheels.com/page29.htm
.................... Sealing Tapes and Control Seals along with Zig-Zag Turbulator and Dimple Turbulator Tapes (also called trip tapes -- "they create a rough place for the laminar flow to "trip over" into minor turbulence before separation occurs due to body shape. This reduces drag because this turbulence keeps the flowing air closer to the body than if it wasn't there, therefore reducing profile drag.", the Rev. H+.
Also here................
http://purplesagetradingpost.com/sumner/bvillecar/bvillelinks.htm
.................I have a lot of aero links under "Aerodynamic Info and LSR Calculator/Spread Sheet Sites",
Sum
I think you've got the theory of why it works figured out. It's the same reasoning behind the vortex generators that come stock on some Mitsubishi Lancers. I'd guess dimpling could even be considered to be vortex generators (VGs).
Streamliner and lakester classes wouldn't benefit much if at all by them since they tend to be designed so that you don't get the flow separation where the VGs become helpful. Where VGs would be most beneficial are on cars that are relatively stock bodied like /GC or /PRO. But... if I read the rule book right, vortex generators are prohibited in those two classes.
Mike
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Mike, the rulebook is pretty clear on what a vortex generator is “ Sharp edged devises placed on the body for the proposes of creating flow vortices”. I don’t think dimples would fall into this category from a definition standpoint. You could create he same effect with a properly textured paint job.
Some of the NASCAR boys have figured this out and have gone with the full body wraps. They use a product called Control Tec, by Scotch. Cant remember the thickness of the product but it has an interlocking pattern to it. The company response is that it helps with applying the material on to the car, but a definite plus is the textured feel.
It is next to impossible trying to write a rule for this. Its like policing traction control.
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Posted by -- maguromic, Location: Palo Alto, CA Re: Golf Balls
« Reply #21 on: March 20, 2008, 11:12:47 PM
There has been some research in the Texas A&M low speed wind tunnel on wheel disks with dimples, which showed very good Reynolds numbers compared to non-dimpled wheel disks. They concluded any where from hexagons to icosahedral (20 sided) shapes worked well as the corners that trip the airflow to create the effect. The drag reduction and wake reduction was considerable also. But the practical side, it is very expensive and difficult to make multi sided dimples.
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HA!!. So it's in the public domain. No point in rushing to the patent office. Who wants to be a millionaire? Here's the DNA for the business plan...............Next automotive aftermarket equipment craze. Out with silly "Tonka" wheels. In with wheel discs that not only evoke the bleeding edge of high speed Bonneville technology for increasing mileage through streamlining; BUT ALSO allow ventilation for everyday cooling of disc brakes.
Aluminum wheel discs Bonneville style spun from .060 dia perforated aluminum aluminum sheet and use OEM style wheel disc attaching hardware.
"Your cake and eat it too" for only $400 a set of 4. Or if you insist on a pretty pattern for the holes do them with a CNC turret punch before you spin them. Maybe even do custom patterns for 3x the regular price.
C'mon ------ One of you young Southland tigers with some fab shop contacts and enough whits to promote it right go make enough bucks off of this to fund a serious streamliner project!! Who's gonna do it??
Ed Weldon (this old man needs absolutely no piece of the action -- it's a freebie!)
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Mike, the rulebook is pretty clear on what a vortex generator is “ Sharp edged devises placed on the body for the proposes of creating flow vortices”. I don’t think dimples would fall into this category from a definition standpoint. You could create he same effect with a properly textured paint job.
I have a 2006 copy of the SCTA rulebook which may be a little outdated. Section 4.CC.8 simply reads "Vortex Generators: Aerodynamic devices mounted on the body for the purpose of creating flow vortices". That seemed generic enough to me to cover a wide range of aerodynamic trickery.
Mike
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I think why the wording was changed and I am only guessing is that the louvers fit into the rules as well, and lots of classes allowed them. I don’t know about other classes but on fuel/gas roadster you are allowed louvers on the deck lid. Where you place them will help you in the aero side. My roadster was designed with the help of Stanford University Engineering School and all the aero work was done on the computer and we played around with the louvers on the deck lid till we found the optimal spot to place them. Paul Vanderley (sp) put his ’33 roadster in a NASCAR wind tunnel and came up with a pattern for the louvers on the deck lid of a ’33. As mentioned in another thread it’s not the hole you punch in the air that is important, it’s how you exit the hole.
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When I was younger and didn't mind the occasional fight, I used to win money in bars on the dimple question. It took finding an aero professor to arbitrate and beer glasses sometimes flew settling the question, but geeks have to have their fun.
When a golf ball is struck by a driver at a low angle, high velocity, and low spin rate, it pretty much goes straight whether it has dimples or not. The rotation of the ball drags the boundary layer along with it, more so if the ball is dimpled. Now, the thicker boundary layer of the dimpled ball causes more drag than the thinner boundary layer of a smooth ball. But as the dimpled ball slows down relative to its backspin rate, the thick, rotating boundary layer creates lift. This lift causes the ball's flight path to rise and carries it farther than it would without spin and without dimples. This is why even a driver has some angle to it.
Higher angle clubs create more spin rate vs. velocity and so the ball gets a greater percentage of its vertical trajectory from spin for the higher numbered clubs. All of these effects are dependent on velocity and air density. On the moon, dimples make no difference.
So the dimples create more drag, not less; and this makes the ball go farther. Take some Tylenol.
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When I was younger and didn't mind the occasional fight, I used to win money in bars on the dimple question. It took finding an aero professor to arbitrate and beer glasses sometimes flew settling the question, but geeks have to have their fun.
When a golf ball is struck by a driver at a low angle, high velocity, and low spin rate, it pretty much goes straight whether it has dimples or not. The rotation of the ball drags the boundary layer along with it, more so if the ball is dimpled. Now, the thicker boundary layer of the dimpled ball causes more drag than the thinner boundary layer of a smooth ball. But as the dimpled ball slows down relative to its backspin rate, the thick, rotating boundary layer creates lift. This lift causes the ball's flight path to rise and carries it farther than it would without spin and without dimples. This is why even a driver has some angle to it.
Higher angle clubs create more spin rate vs. velocity and so the ball gets a greater percentage of its vertical trajectory from spin for the higher numbered clubs. All of these effects are dependent on velocity and air density. On the moon, dimples make no difference.
So the dimples create more drag, not less; and this makes the ball go farther. Take some Tylenol.
gee...... I thought the dimples in a golf ball were there to help keep it aloft............ so it could fly farther.......... hmmm :wink:
You said it better, thanks
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Blue
Is supercavatation possible with a streamliner?...I know it is unacceptable in aircraft as it takes away the control surface action.... :?
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http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
The dimples reduce flow separation and thus drag on a sphere.
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http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
The dimples reduce flow separation and thus drag on a sphere.
Sorry, the evidence doesn't support this explanation. Go out to a golf course, stand behind the tee, watch the ball. It does not travel in a decaying parabola, it lifts above this path partway through its flight. This vertical deviation increases with both spin and the sharpness and number of the dimples.
Going through months-old posts looking for ways to post someone else's contrary information is a lot less productive to your education than joining an actual race team. :-D
I read a few of aerospaceweb's other answers, interesting that they couldn't explain how wings work and which of the "theories" presented applied to the various areas of airfoil design. I could, and did here in a way that even non-aero people can understand. My professors always said that if you can't explain it to someone outside your field, you really didn't understand what you were talking about.
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http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
The dimples reduce flow separation and thus drag on a sphere.
Sorry, the evidence doesn't support this explanation. Go out to a golf course, stand behind the tee, watch the ball. It does not travel in a decaying parabola, it lifts above this path partway through its flight. This vertical deviation increases with both spin and the sharpness and number of the dimples.
Going through months-old posts looking for ways to post someone else's contrary information is a lot less productive to your education than joining an actual race team. :-D
I read a few of aerospaceweb's other answers, interesting that they couldn't explain how wings work and which of the "theories" presented applied to the various areas of airfoil design. I could, and did here in a way that even non-aero people can understand. My professors always said that if you can't explain it to someone outside your field, you really didn't understand what you were talking about.
http://www.sciencenetlinks.com/sci_update.cfm?DocID=23
Isn't the golf ball lift just Magnus effect like when someone points a leaf blower straight up and positions a beach ball over it?
http://query.nytimes.com/gst/fullpage.html?res=9C04E6DA143EF934A35752C0A9659C8B63
I have read two theories of lift for wings. One is the classic explanation based on Bernoulli. The other is a Newtonian explanation that lift is an upward thrust resulting from the downward diversion of air.
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Man I had forgotten about this thread but i am going to take a small ball pein hammer to my helmet now!! Dimples here we come look out avionics the ACNE MAN cometh.
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I thought I recalled Mr Dolan saying that the Pettys put the vinyl roof on to cover up an overly acid dipped roof on the car, but I could be wrong
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I thought I recalled Mr Dolan saying that the Pettys put the vinyl roof on to cover up an overly acid dipped roof on the car, but I could be wrong
The story is correct from more than one source I have in stock car (NOT nascar) history.
As an aero geek, I have to question how much of the drag reduction came from the turbulent boundary layer staying attached due to the vinyl and how much came from the turbulence from the joints.
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The Penske '69 Trans-Am car also had a vinyl roof. It was rumored to be because the the roof was too thin from acid dipping the body. But knowing Penske who knows what they were using it for. His accomplishments speak for them self!
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Penske was know for giving you something to see to keep you from looking somewhere else where he didnt want you to see. When drag racing an NHRA stocker Mustang Cobrajet in the early 70's we would put the wrong dual inlet fuel line on so they could make us change it to the right one, a single inlet. If you didnt give them something to pick on they would keep looking. Once they busted you they were happy
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"The Penske '69 Trans-Am car also had a vinyl roof. It was rumored to be because the the roof was too thin from acid dipping the body. "
Turning a Javelin that originaly had 70/30 weight distribution into a Trans Am winner must have required quite a bit of acid dipping .
John
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Let's see... If you put a lot of dimples on your car, then spin it real fast, you can generate a lot of lift. If that is what you want, to climb skyward like a golf ball, I would rather not see it in action. By the way, have you seen the NACA ducts in the rear quarter panel windows of NASCAR cars? Hopefully, they generate positive pressure to pipe air to the drivers, etc.
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Free dimpling
As some of you know we have been having some pretty wild weather in Iowa this year. Hail is again predicted for today. Yesterday tennis ball size (2.5") hail fell about 60 miles from where I live. Not only will it dimple the shell but it will also probably change the ride height. :-D
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So if dimples cause lift which would for all intensant purposes in effect reduce weight they could be placed at strategic areas to re distribute the said weight.Dimple the roof floor pan and sides add spoilers to get traction at speed ???
Nah Maybe not.
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Just curious why some of the new Lexus's come with dimpled floors. They say its to cut down on wind noise and to help with fuel mileage. If the wind noise is caused by friction then it would seem to be good way to cut friction. I have to think with Toyota's budget and their race teams to draw on that it was working. The tooling cots alone would make them think twice before doing this. I am not a aero guy, so what do the aero people think?
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IMO Dimpling your step pan may cause you some heartaches because the word "flat" is in the definition. With a belly pan it would not make a difference. Good luck
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JD, I agree with you about the step pan. Just trying to get the opinion of the aero guys when its been said on this thread it doesn't work and adds lift. But a company like Toyota with all their resources and F1, NASCAR testing does something like this. Makes us non aero guys wonder.
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maybe it was done to make a thin piece of crap metal seem much thicker and stronger just a thought willie buchta you guys need to go back and print out blues posts and read them until you understand --if you want to go faster he is telling you how to do it (for free) IF YOU JUST LISTEN
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Just curious why some of the new Lexus's come with dimpled floors. They say its to cut down on wind noise and to help with fuel mileage. If the wind noise is caused by friction then it would seem to be good way to cut friction. I have to think with Toyota's budget and their race teams to draw on that it was working. The tooling cots alone would make them think twice before doing this. I am not a aero guy, so what do the aero people think?
This is to prevent the wind from resonating at a low frequency and turn the wind noise into an upper broad spectrum of "white noise". White noise is easier to attenuate and insulate from, especially mixed higher frequencies.
"Lift" from dimples relies on spin and is not applicable to vehicle surfaces.
Dimples are a boundary layer energizer for VERY low Reynolds numbers. At LSR Reynolds numbers, zig-zag tape and VG's are the turbulator of choice.
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Hey Willie there aint no way I am seriosly going to start dimpling a years work now the final thros are all coming together, but I do think the ultra polished streamlined bodys of some racing streamliners and many other vehicles could do with a bit of playing with in wind tunnels not to say "dimples" but ripple finishes and many other textures! smooth and flat may not be where its at Jeeeze I am a poet and i didnt even know it.
TTFN