41 replies to this topic

[IndyIan]

I've been reading about Michelin's new "tweel". It sounds exactly what an F1 suspension engineer would want. Seperate tuneability of lateral and vertical stiffness, no compensating for changing air pressure as the tire temperature goes up and down. Probably a very adjustable contact patch too. No flats either!

The F1 regs say a tire must be inflated but I imagine simply enclosing the sides of the tweel and inflating it to 2psi would satisify the regulation without effecting the tweels performance.

Maybe bridgestone or michelin is already testing them?

Ian

[desmo]

Interesting concept, sort of a natural outgrowth of the run flat concept. I can't find out anything technically substantive about it online, just the usual shallow PR fluff. Seems aimed at the diametric opposite of the high performance-racing market- wheelchairs, segways and military vehicles. My intuitive sense is that these will never be seen in any even remotely sporting performance application, nevermind F1. Any tire boffins or vehicle engineers like to comment?

[Engineguy]

Let us not forget Michelin invented those wacky radial tires fifty years ago; they've turned out somewhat successful. Although the initial commercialization seems headed toward construction machinery and personal transportation devices, they certainly are well along on passenger car application development.

Benefits of Tweel™ :
The heart of Tweel innovation is its deceptively simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tires. The flexible spokes are fused with a flexible wheel that deforms to absorb shock and rebound with unimaginable ease. Without the air needed by conventional tires, Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to "envelope" road hazards.

Michelin has also found that it can tune Tweel performances independently of each other, which is a significant change from conventional tires. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimized, pushing the performance envelope in these applications and enabling new performances not possible for current inflated tires. The Tweel prototype, demonstrated on the Audi A4, is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to within one percent of the fuel economy of the OE fitment. Additionally, Michelin has increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling.

I can see great performance promise for this... a conventional tire is an inexact blob (albeit a highly developed inexact blob) by comparison. Current tires use complex belt solutions to support the shape of the tire... I wonder if these would be much simpler and cheaper to produce.

[dolomite]

What material(s) is it made of, does anybody know?

[Jhope]

found a good artile here:

http://www.nytimes.c...&partner=rssnyt

[Greg Locock]

Very interesting. That is practically a direct physical copy of the most advanced tyre model I use. The ability to decouple vertical and lateral stiffness is a huge bonus, I'd be very interested in the torsional compliance as well.

My guess is that they will transform the steering feel of the cars that they are used on, and will behave like super radials, that is, an even less progressive breakaway than radials, compared with cross plies.

However, that could be engineered out of them, by adjusting how much, and how, the contact patch distorts with lateral load.

I want some to play with, NOW.

[dolomite]

Originally posted by Jhope
found a good artile here:

http://www.nytimes.c...&partner=rssnyt

Thanks!

[Greg Locock]

Just thinking about it the torsional compliance at the contact patch is pretty much related tot he lateral stiffness. The belt is constrained by the lateral stiffness of the bits at 3 and 9 o'clock.

You could add more torsional stiffness by increasing the depth of the flexible blades as well.

This tyre has the potential to substantially reduce the time delay involved in steering the belt, which is of the order of 300 ms for a typical tyre and event.

[Bluehair]

I like this one. Looking at the current set up, it seems that tires should be allowed to have different pressures within the tyre via the use of chambers. Imagine a wheel with 5 narrow tires mounted to it. The inner most tires might have slightly less air pressure than the outer tires (due to camber settings, or whatever). This configuration would be far too heavy, but perhaps the tweel can simulate some of the potential benefits without too much of a weight penalty.

Looking forward, I can imagine the tweel taking over more of the suspension duties than what the current tires are doing today.

Now if the spokes could somehow expand and contract... there's goes the gearbox!

-Bluehair

[Shiftin]

How is that for a dumb tyre question? But in all honesty, isn't it possible to make a (mixed) rubber compound that is less sensitive to tyre wear and still gives enough flexibility to give some kind of suspension? Why does it have to be air instead of a more solid material...?

I do not know anything about technical stuff at F1 but I am a kind of McGuyverish practical person. So I'd say I would fill the inside of the tyre with some kind of foam-rubber. Able to flex, unable to go flat...

I know it will be 'impossible' (replace the inner core? (foam-rubber)) to adjust the air pressure in the tyres but it will give some other benefits I guess...

[Shiftin]

Maybe I am very full of **** but that's why I come here. To have my theory tackled or confirmed. But what about a bunch or air-filled chambers (like foam-rubber) but bigger (like golfball size). You will never have instant depletion with all the dangers that brings...

Dunno, I sound very logical when I say this to myself but it can't be that simple...

[McGuire]

For weight and cost, air has a decided advantage over many other materials.

As an added bonus, supply and availability are generally not an issue. Also, air is one of the few spring mediums which does not suffer a fatigue cycle. About as good as anything one can stuff in a tire, all things considered.

That said, if we put the air in the tire at atmospheric pressure then we don't have to worry about it leaking out (or in, hmm). We can simply build the required compliance into the sidewalls and carcass. Then we have the "run-flat" tires of recent note. They work perfectly fine... except at this stage of development the ride is pretty bad.

[jonovision_man]

On the last Champ Car broadcast, they said they use Nitrogen instead, since it has less water content I guess it doesn't expand as much when it gets hot.

Same for F1?

BTW - what about these?
http://www.michelinm...e01102005a.html



jono

[Shiftin]

Those are some cool tyres jonovision_man Are they serious about them?

But seriously, I will not be 'defended' that easlily... I made this rough drawing of what I mean, and please don't bitch about the details (like grooves and such...;) )

[IMG]http://img273.images.../tyre1dk.th.jpg[/IMG]

McGuire,

I understand that costs are a important thing, but losing a race because a tyre blows (ripping the bodywork) apart also costs a few $...

What do you think. Should I start making Shiftelins/Shiftstones or get my ass back in to the Paddock Club..

[jonovision_man]

Originally posted by Shiftin
Those are some cool tyres jonovision_man Are they serious about them?

I believe so... here's what they say the benefits of the "Tweel" are:

Benefits of Tweel™:

The heart of Tweel innovation is its deceptively simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tires. The flexible spokes are fused with a flexible wheel that deforms to absorb shock and rebound with unimaginable ease. Without the air needed by conventional tires, Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to "envelope" road hazards.

Michelin has also found that it can tune Tweel performances independently of each other, which is a significant change from conventional tires. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimized, pushing the performance envelope in these applications and enabling new performances not possible for current inflated tires. The Tweel prototype, demonstrated on the Audi A4, is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to within one percent of the fuel economy of the OE fitment. Additionally, Michelin has increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling.

Who knows. Or maybe it's like Reagan's "Star Wars", just trying to get competitors to bark up the wrong tree?

jono

[Shiftin]

Very interesting!

It wouldn't surprise me if this is the way to go. It makes a lot of sense, actually. I am not sure they look as good on a car as 'normal' wheel/tyres. But I also think this is a very small 'minus'....

[tedmna]

In reading about the Tweel iirc the big problem is the ability (or lack of the ability) of the Tweel to respond to cornering forces. It may not be bad for drag racers and american drivers, then.

[Shiftin]

Originally posted by tedmna
In reading about the Tweel iirc the big problem is the ability (or lack of the ability) of the Tweel to respond to cornering forces. It may not be bad for drag racers and american drivers, then.

Not if the spokes (speeks?) are flexible, as stated in the article...

But this thread is about Shiftelins, not about some lame ass idea Michelin came up with, dammit!;)

[Bob Riebe]

Two questions about non "air" tires:

A--- minus 40 degrees F, varying surfaces.

B--105 degrees F, varying surfaces.

Bob

[Powersteer]

http://www.michelinm...e01102005a.html



It looks so cool. If those wires can be replaced by some sort of foam to make it really light. If the contact patch surface could be tailored with such a device it would be most beneficial. Seems that Michelins formula one exploraition has concerntrated strongly on contact patch with this and the opt system surfacing.

[asidrayne]

The 'wires' you noted are actually webs that extend across the wheel, not wires.

[desmo]

There's a twheel thread around here somewhere already started...

[imaginesix]

The only thread I can find with the word 'twheel' in any forum in the past 6 months is this one.

I wanted to say that the biggest advantage of such a wheel design would be to allow the elimination of the spare tire. Though I imagine there may be the possibility of designing such a tire with a tread that evacuates water through the tire as well as around it.

Tires are really some remarkable things. If you consider that the original idea of putting a rubber balloon around a wheel was probably only intended to soften the ride, the fact that cars could not work at all without them even today is bewildering. Or was the first tire tried out with the understanding that it would allow very accurate control of the vehicle? I doubt it.

From that perspective, the advent of tires is perhaps the only real revolutionary occurence (no pun intended) in automotive history. All other technologies evolved based on the need to address specific problems as far as I can tell.

[desmo]

It was spelt 'tweel'. I've just merged them.

[soubriquet]

Originally posted by imaginesix
Tires are really some remarkable things. If you consider that the original idea of putting a rubber balloon around a wheel was probably only intended to soften the ride, the fact that cars could not work at all without them even today is bewildering. Or was the first tire tried out with the understanding that it would allow very accurate control of the vehicle? I doubt it.

Dunlop is generally credited with inventing the pneumatic tyre. They were for use on bicycles. A combination of no suspension and gravel roads would have been quite, ahem, tiring.

[Greg Locock]

Advantages:
robust
reskinnable (maybe)
very high conical stiffness (that is SAT/toe)
high lateral stiffness (Fy/dy)

Disadvantages (so far)

noisy

[imaginesix]

Most of those advantages are tuneable, or should be if the techonology matures to a stage where they supplant current technology. Besides, you're guessing.

[Greg Locock]

No, I read the statements from Michelin. Do you? If not, what on Earth are you on about?

[imaginesix]

Whoa, relax big guy. I read what I could find many months ago, and don't remember seeing any detail whatsoever.
So you weren't guessing. I just thought you were extrapolating the twheel's characteristics from those of "...the most advanced tyre model I use". See? I do read.

[Greg Locock]

http://www.michelinm...e01102005a.html

If you look at how tires work as springs then you get high sat stiffness hand in hand with high latforce stiffness.

So that factor of 5 is a huge step forward.

http://www.cbsnews.c...ain669888.shtml

mentions the noise problem.

[m9a3r5i7o2n]

Does anyone remember the tire that Firestone came out with about 20 or thirty years ago, it was revolutionary! Where did it go?
Good talk never replaces a good actual display of the product. Has anyone seen it run and go round the bend? Although a non flat tire would be a blessing.

Notice also that the thing was brought out in the U.S.A. so the French can probably blame the Americans for its failure.
M.L. Anderson

[Franklin Ratliff]

Originally posted by Shiftin
How is that for a dumb tyre question? But in all honesty, isn't it possible to make a (mixed) rubber compound that is less sensitive to tyre wear and still gives enough flexibility to give some kind of suspension? Why does it have to be air instead of a more solid material...?

I do not know anything about technical stuff at F1 but I am a kind of McGuyverish practical person. So I'd say I would fill the inside of the tyre with some kind of foam-rubber. Able to flex, unable to go flat...

I know it will be 'impossible' (replace the inner core? (foam-rubber)) to adjust the air pressure in the tyres but it will give some other benefits I guess...

Air is lighter and doesn't deteriorate from heat.

[Greg Locock]

...and polyurethane doesn't leak out through pinholes.

The reason that Michelin announced this in the USA is of course unknown, but perhaps might have something to do with, ahem, certain recent court cases involving people overloading underinflated tires and exploding them. At least if we fill the tires with plastic they won't have to waste their valuable time pumping them up.

[imaginesix]

The only overloading/underinflating problem that I'm aware made it into the media was Firestones on Ford trucks, five years ago. What's the big 'crisis' being averted this time?

[wheelock]

For practical regular use, I feel they would benefit from some sort of shield to enclose/cover the spokes.
Otherwise the gaps in between them could make great stone, mud , foreign object traps, creating
safety and wheel balance issues.



Mark

[Greg Locock]

Guess which companies are in court as we write?

[imaginesix]

Companies? Ford and Firestone?

You give the public too much credit if you think they will recognise in the Michelin Tweel a device that could 'save' them from the fate that befell the Firestone owners. At least, that's the only angle I can see that might have some PR value for Michelin.

[Greg Locock]

PR? Who do you think Michelin are trying to sell it to? Not the general public, I promise you.

[desmo]

Potential military applications were cited in the original press release I think...

[soubriquet]

How about any application prone to punctures. Mining companies, and off road for a start, but as wheelock pointed out above, they would need to be shrouded to keep them clear of rubbish.

[wheelock]

Really huge versions would be great for big industrial machines ,earth movers etc.
These tweels seem like a development of those one piece molded caterpillar
tracks uses on small diggers etc, well thats what they remind of.


Mark

[m9a3r5i7o2n]

The Ford/Firestone debacle might not have been caused by just the tires and underinflation alone. If one checks on the Anti-sway bar one can’t help but notice the lack of a bar of sufficient diameter to help the car under cornering attitude. If Ford made this mistake how many others did they also make on the general suspension layout?

Also see the sparkplug blowout situation due to the threads on the plug being too short!

http://www.consumera...ford_spark.html

M. L. Anderson