Landracing Forum
Tech Information => Technical Discussion => Topic started by: Hans Blom on October 31, 2006, 06:51:11 AM
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I was wondering if anyone has any knowledge of the effect that the rotation of the front wheel(tire) has on the flow of air around the front tire. I have tried doing some googling of rotating bodies and such but haven't really come up with anything. Just wondering things like if the rotation has an affect on the height of the resulting dead space behind the wheel and the same for the width. Obviously the coarseness of the tread would also have some effect, but how much?? Probably not much here, but you would think a slick tire would have slightly less turbulent air at the surface of the tire, maybe making a smaller area inside your shear line, which could be good or bad depending on the tire size and the bike itself....
Hans
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yes
I have a lot of tunnel data and great pix of a rotating tire being smoked in a tunnel. i still cant figger out how to post pixs on this site yet, if someone can help tell me how then i'll let everyone see 'em
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yes
I have a lot of tunnel data and great pix of a rotating tire being smoked in a tunnel. i still cant figger out how to post pixs on this site yet, if someone can help tell me how then i'll let everyone see 'em
Kent you have to either:
Upload them from your computer using the "add attachment" option when you post,
or
you have to have them on a site that is on the internet and then you post a link to them on that site such as this:
{IMG}]http://picture address{/IMG}
replace the { with [ in the example about and } with ]. To put in the link go to the picture you want to link to and "right click" on it then go to "properties", next highlight the "address (URL)" with your mouse and right click and copy the address and past it into the above where it says http://picture address.
It sounds complicated, but it is easy once you have done it a couple times.
Another option is to go to "viewer picture post" on the site and do it there.
Or last e-mail them to me or someone else and have them post them. I'm on dial up, so if they are a couple meg's forget me :wink: .
........and yes I would like to see them.
c ya,
Sum
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yes
I have a lot of tunnel data and great pix of a rotating tire being smoked in a tunnel. i still cant figger out how to post pixs on this site yet, if someone can help tell me how then i'll let everyone see 'em
Somebody please help Kent post these pictures. I've been looking all over for a tunnel picture of a rotating tire. I haven't had much luck posting pictures here either.
Kent,
If you still don't have any luck with posting I'd like to PM you with my E-mail address.
Harvey
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I would love to see that , I'll be watching in anticipation! is this work you did yourself or some other data?
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I have heard that the 'pumping losses' can be significant. (you might try googling 'aerodynamic pumping losses'). It was recommended to fit a piece of metal or plastic, angled and contoured to closely fit the tread of the tire to 'shave off' the air that would otherwise just go around and around. Haven't tried it, but intend to.
Thanks,
Jim.
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Kent,
Send them to me and I will "host and post" them for you.
Thanks,
J
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The first use I saw of the "PUMPER STOPPER" inside the fender was soft
plastic that would wear away as the tire would expand at speed and take
the proper shape to form a seal.
It was out of sight and not shown to others.
That was in 71 and tested by a still prominent Pro Stock MC team. :wink:
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Kent, any luck with the aero info???? Thanks, Hans
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The first use I saw of the "PUMPER STOPPER" inside the fender was soft
plastic that would wear away as the tire would expand at speed and take
the proper shape to form a seal.
It was out of sight and not shown to others.
That was in 71 and tested by a still prominent Pro Stock MC team. :wink:
JackD,
I'm gonna have to call George Bryce and ask him about that one :?: .As None of the School Bikes had them?I got my NHRA PSM Lic from him last year 8) !
I'm pretty close to the PSM Chassie God so I'll call him and ask him also! :wink:
I've got to go against those Turbo Hayabusa's with my Little V-twin"DOHC",and NEED ALL THE HELP I CAN GET :cry:
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The first use I saw of the "PUMPER STOPPER" inside the fender was soft
plastic that would wear away as the tire would expand at speed and take
the proper shape to form a seal.
It was out of sight and not shown to others.
That was in 71 and tested by a still prominent Pro Stock MC team. :wink:
JackD,
I'm gonna have to call George Bryce and ask him about that one :?: .As None of the School Bikes had them?I got my NHRA PSM Lic from him last year 8) !
I'm pretty close to the PSM Chassie God so I'll call him and ask him also! :wink:
I've got to go against those Turbo Hayabusa's with my Little V-twin"DOHC",and NEED ALL THE HELP I CAN GET :cry:
Kaz,
He is not talking about Star racing..
J
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Enough people saw it from 2 other OEM groups that it was not a speed secret or I wouldn't repeat it..
They may have developed other methods since but it did work.
You don't think they would let you go to school on a top of the line bike with all the tricks do you ? :wink:
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Enough people saw it from 2 other OEM groups that it was not a speed secret or I wouldn't repeat it..
They may have developed other methods since but it did work.
You don't think they would let you go to school on a top of the line bike with all the tricks do you ? :wink:
Chip's Bike was there :shock: .It was being Bought by The Big Cheese of S&S 8) .There were a couple Executives
from S&S Taking the Class with me :shock: .As George wanted them to know what it was Like! :twisted:
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Im not sure about the effects of plastic rubbing against rubber.
Is that going to create large amounts of heat anf static electricity?
Are there any documented aero performance gains?
Regards Whitworthsocket
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The material used for the gate is soft polyethylene and only actually touches the tire at the highest speed attained with no friction loss and resultant heat.
The effect is to stop the tire from pumping air between the fender and the tire.
The results will vary with the application and speed.
The effect is measurable on a test stand but hard to measure from run to run on a bike.
If you want to stop the air, there you have it.
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Guys,
There is some decent data on the flow over rotating / covered / uncovered wheels in a few easy to grap publications.
First is Race Car Aerodynamics by Joseph Katz ISBN 0-8376-0142-8
Next is Vehicle Aerodynamics Recent Progress SAE-855 ISBN 1-56091-119-0
Made up of various SAE papers.
Sorry that I did not post this earlier. I thought that I had done so. So much for total recall being the sign of a healthy mind! LOL
Regards to All,
HB2
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harold- there are a lot more things that can be a sign or not of a healthy mind/body/ or whatever.
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First is Race Car Aerodynamics by Joseph Katz ISBN 0-8376-0142-8
Next is Vehicle Aerodynamics Recent Progress SAE-855 ISBN 1-56091-119-0
Made up of various SAE papers.
Harold,
Are these both from a car perspective (not a motorcycle perspective)?
Thanks!
Deb
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The references are for covered and uncovered wheels. Could apply to mc, autos, aircraft, etc. The study of these sort of things can be adapted to various applications. However, if you can be patient, I can perhaps get some specific information on motorcycles done in the USAFA low speed tunnel(s) and perhaps some othere mc related information. I do know that the previous reference to the anti-pumping device (simplified) is correct.
You know, it is fairly easy to build a "profile tunnel" so that you can take a look at how smoke or other flow visulation tools allow you to see patterns around and through devices. You can use a regular flowbench as the signal generator or build a much more simple device.
Regards,
HB2
Snowed-in The High Country
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THX Harold for the observation about anti-pumping.
One can read up and study the theory in reference manuals from every where.
But until Manuel simply understands it , it won't do him any good. :wink:
"Theoretical records are set by theoretical race vehicles."
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I have never understood why some (most) of the folks at Bonneville go around and knock the salt out of the wheel wells on the fendered vehicles. The salt is built up and performs very much like the anti pumper scheme that you mentioned. The buildup of salt directly behind the wheel/tire units are actually trying their very best to help streamline and decrease the exit loss of the rotating pumps.
Let me see, it is something like the relative speed of the wheel/tire at the top vs the bottom and the traction surface.....or something like that. LOL
SO, I guess a guy could make similar devices out of either ethafoam or styrofoam and sort of "seed" the salt buildup.....well, at least the stuff is white (so it looks right).
Regards,
HB2
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Harold has figured out the wet salt collects in the low pressure area that you would do well to fill to allow the air to go by cleaner and won't shut up.
He even mentioned Styrofoam !
What can be done ? LOL
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Oh yes, I will now start to shut up on the subject....Now that I have learned that you are a C130 guy!
You probably don't like the "safety nets" 'cause they remind you of the seat webbing! LOL
You probably didn't bother to wear a safety tether after a while either. LOL
Guess I had better LOLEX outa here.
Regards,
HB2
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Send a 10k load plus the pallet from the front of the bay that is trimmed to fly low and slow ,out the back door by tossing a chute will cause a 130 to do strange things.
It makes a lot of other stuff seem easy.
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You may have seen Jack drop a load or two and just didn't realize it.
To refresh your memory:
http://www.micom.net/oops/Air-drops.wmv (http://www.micom.net/oops/Air-drops.wmv)
Bonus! Jack's top secret Bonneville launch technique in this video!!!
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Those were all test shots at Eglin AFB.
Our stuff was in RVN in 69 and the first thing that is not shown was the big booms from the big bombs that cleared the jungle and stuff.
Someday, ask me about building the World's Largest Tit with one of those 60ft chutes painted pink.
It was a real photo opportunity.
Those in the film were all sissy drops with nobody shooting at you, LOL
SSGT Dolan 555 CES-USAF 66-69
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way off topic ....... but ...........
Don't know what you were dropping or where you were dropping it but THANKS for doing it.
Sgt. E-5 Strong 2/17 Artillery Binh Dinh Province '68
DS
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Knowing how to keep yer head down and yer butt too was a real important lesson in streamlining and was very effective on other things like going fast on a motorcycle.
If you didn't learn those things fast, you were going to go fast ,but not on a motorcycle. LOL
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Seen the inside (while riding) and the outside (while entering/exiting and during resupply) of 130's and learned early on that when it is your turn it is your turn. Very fortunate that it has not yet been time to punch my ticket. It does however make one appreciative of the little things.
And you Jack, might have snorted too much agent orange! LOL :-D
And the only way that they will get me on a chopper again is on flight for life if I can't fight back!LOL :roll:
The Spectre AC130s that are flying today have undergone (some not all) a field mod that cleans the things up so that they can stay on station longer. All due to the applied naivete of some AFA Cadets that just wondered "what if" and accomplished same.
Cleaning up what is already working is not for everybody. Sorta like camouflage in that what you see is not necessarily what you get.
Regards to All,
HB2
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Way over my head and beyond my expertise, but we have used the same material in the orchards for years (without the dye). Don't know what that means. Maybe that's my problem. Maybe that's what makes us want to go fast. On the subject of salt buildup in wheelwells, I remember when Don Debring first started, he was running really fast for the size for his power plant. Don't remember exactly what size but it was the motor out of his wife's car. Down run went great, I think it was in excess of 260 mph and on the return run things were not going as well and Don just kept upping the boost as the run progressed until it blew the motor up. It turns out that the wheel wells were being packed with salt and acting as a brake. You need to have at least enough room for the salt to not drag on the tires. Every year the salt is different. Need to be prepared for any and all eventualities.
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Close fitting fenders, fender well liners, and tire wipers won't tend to collect salt.
Polyethlene sheet with WD-40 sheds the salt really well if in places you don't want it to stay.
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But you do need a venue for the salt to exit. Tires will pick it up, especially if it is wet.