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Author Topic: how wide should the wheels be?  (Read 8623 times)

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Offline Jonny Hotnuts

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how wide should the wheels be?
« on: October 04, 2007, 11:25:18 AM »
Lets say someone wanted to run aluminum spinners (como el liners de Jack Costella proque 12" y no 8") that were 12" in dia but available in any width. I can see if they were too thin they would dig like ice skates on sand and if they were too wide they might "skip" and not be effective in turning.

So is there any rule of thumb reguarding the frontal contact patch size?
And are there any other concerns when using solid wheels like these?
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Offline tortoise

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Re: how wide should the wheels be?
« Reply #1 on: October 04, 2007, 12:37:33 PM »
And are there any other concerns when using solid wheels like these?
Mainly, they are able to generate very little steering force. You'd want a car that aerodynamically really likes to go straight, and the longest possible wheelbase. Muy despacio steering, too.

As to width, a good guess would be to have a contact patch to weight on the wheel ratio about the same as you-know-who.

Offline JackD

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Re: how wide should the wheels be?
« Reply #2 on: October 04, 2007, 12:39:05 PM »
A zero contact patch will produce zero ability to transfer energy.
Something has to be deformed as the round part tries to grip the flat part .
Fail that, or leave a mark in the salt due to the design and you will bring down a lot of heat.  
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Offline tortoise

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Re: how wide should the wheels be?
« Reply #3 on: October 04, 2007, 01:20:00 PM »
. . . leave a mark in the salt due to the design and you will bring down a lot of heat.
An excessive mark, you must mean. Surely all vehicles leave some mark. Somewhere along the line, some official decided Costella's machines weren't a threat to the salt. Do you think that was a bad call?

Offline JackD

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Re: how wide should the wheels be?
« Reply #4 on: October 04, 2007, 06:23:40 PM »
The design and it's effect on the condition of the surface dictates that call. :wink:
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Offline Jonny Hotnuts

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Re: how wide should the wheels be?
« Reply #5 on: October 04, 2007, 07:34:38 PM »

http://www.fiatforum.com/gallery/data/500/small_copy.jpg?8455

Jack, here is what I am thinking of.

I was considering using a series of rounded edge groves on a relatively wide surface area. The grooves should provide a lower slip coefficient (and hopefully better steering) while the overall width should prevent digging and possibly damage to the salt. If the aluminum wheels are the same width as my current tires (providing the weight is the same) and the edges are sufficiently rounded is there still a risk of salt damage?
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Offline Unkl Ian

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Re: how wide should the wheels be?
« Reply #6 on: October 04, 2007, 07:39:12 PM »
So what is the advantage of these solid wheels ?



And what is the price tag ?



My guess is they will be heavier than the typical pneumatic tires.
I guess the answer is "a Secret" .

Offline Peter Jack

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Re: how wide should the wheels be?
« Reply #7 on: October 04, 2007, 07:44:38 PM »
Jonny:

I don't know how much caster you'll be running but with any amount you'll be up on the single edge of each wheel rather quickly when you make a turn. I'd think you'd be better off with a single more rounded profile with a series of circumferential grooves.

Pete

Offline Jonny Hotnuts

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Re: how wide should the wheels be?
« Reply #8 on: October 04, 2007, 08:02:11 PM »
Peter:

I was going to use a minimal amount of caster for this reason....maybe 5 degrees. I am going to have dampers and have the ratio really high so I was thinking I could get away with 0-5 degrees.


Quote
So what is the advantage of these solid wheels ?
And what is the price tag ?
My guess is they will be heavier than the typical pneumatic tires.


1. Good to any speed (not really a big deal with my car) but you can not find a speed rated wheel suitable for LSR under 22". These will be 12 and should never wear out or blow, but the 12" size is why I am opting for them.
2. I have a place that I can get 12" round 6061 T6 at any thickness......for instance on wheel 4"X12"
is around 150$ I will have the machine work done and will cost in the 50-100 range.
3. I need more forward weight, but at 12" I dont think it will be excessive.
« Last Edit: October 04, 2007, 08:06:37 PM by Jonny Hotnuts »
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"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
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Offline Unkl Ian

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Re: how wide should the wheels be?
« Reply #9 on: October 04, 2007, 10:39:50 PM »
Airplane tires ?
I guess the answer is "a Secret" .

Offline JackD

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Re: how wide should the wheels be?
« Reply #10 on: October 05, 2007, 12:18:16 AM »
Airplane tires sound like an attractive alternative but don't be fooled by the speed or weight rating.
They are designed for a substantial impact on landing and very little duration at what is the rated speed.
They are designed heavy to absorb that kind of load and with the distance you expect to go they will build enough heat to destroy themselves.
The smaller diameter of the wheel and partial contact machined into the surface will further deform the salt as the area goes down.
While you are not transmitting forward motion through them the directional load is what is to be also considered.
Take a metal model of the wheel you propose and run it around a  table.
Now take just a wide rubber band or a series of narrow ones and put them on the wheel and try it again.
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Offline Dean Los Angeles

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Re: how wide should the wheels be?
« Reply #11 on: October 05, 2007, 12:20:14 AM »
Quote
2.F Tires
The use of . . . any non-pneumatic wheel/tire combination (no rubber) must be submitted for approval to the contest board in writing 45 days prior to an event.

The design you are showing is going to plow furrows down the salt. I think that might be a problem. Rubber allows for some compliance with the surface that aluminum doesn't.

In between a pneumatic tire and an aluminum one is an aluminum wheel with neoprene bonded to it. Something around Shore A 60 durometer (about tire tread hardness.)

Yeah, of course, while I'm typing, Jack beats me to the punch.

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Offline Jonny Hotnuts

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Re: how wide should the wheels be?
« Reply #12 on: October 05, 2007, 11:26:52 AM »
I don’t want to seem like I am being argumentative about this as I am only trying to sort it all out.

Dean:
You have a point about the furrows, but the 3d rendering is not to scale (and I may have exaggerated the grooves for the example). The factors to the furrows will be the weight of the car, width of the wheel, depth of the grooves and number of them. I intend to have the “wetted” surface in contact with the salt the same as my current tires patch width. The grooves would only be ¼ to 3/8s deep (not much different from my current tires tread).
I would love to know more about the neoprene ala “grumpy old men” but have no idea where to even start to look for info about doing this.


Jack:
Just curious, if I were to do the same test in sand as supposed to a hard table would my results be different with the rubber bands?

My real question is why the aluminum wheels work for the guys running them in the streamliner classes. Forget the grooves for this question it is just a matter of the wheels serving the purpose of steering on salt and decreased friction.
My car is in the process of being stretched to a 130” wheel base so why is there a huge difference between my car and something like the NT2 when it comes to front wheels?
jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline John Burk

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Re: how wide should the wheels be?
« Reply #13 on: October 05, 2007, 01:01:09 PM »
"why is there a huge difference between my car and something like the NT2 when it comes to front wheels?"

NT2's front wheels carry maybe 30% of 1500 lbs (450) . Your front wheels carry 50% of 2600 lbs? plus the down force from your nose (2000?) .

Offline JackD

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Re: how wide should the wheels be?
« Reply #14 on: October 05, 2007, 01:53:18 PM »
Sand, like the dirt at Blackrock is quite soft.
In the case of the thrust driven vehicle in the dirt, the groves that resulted from them running were a major contributor to the ability to direct the vehicle when underway.
A wheel driven vehicle is slowed so much by plowing a furrow at race speeds , it is not a suitable surface.
Sand is the same thing only different, and mud has the worst features of both.
Deform the surface to the point that others can't follow and you will be sat down on the salt.
When that is argued out to it's logical conclusion we can discuss relative safety.
A well known and very fast biker could be heard screaming over the sound of his ride when caught in a tire groove of a top of the line, wandering roadster,  " Gee I really hope he gets it straightened out soon.":wink:
"I would rather lose going fast enough to win than win going slow enough to lose."
"That horrible smell is dirty feet being held to the fire"