Wet tyre temperatures

[Fozzie]

Hi guys,

Watching the F1 this morning I've had some ideas and questions about tyres in the wet.

Obviously the wet tyres have tread to shift the water and increase grip, but is there a thermal effect whereby the tyre temperature can evaporate water and increase grip that way?

That being the case would it not be better to run slicks as this would increase the amount of rubber in contact with the track? You could use the hardest compound available, heat them up to double the dry temperature and drastically improve wet performance.

I think some teams already exploit this concept but have yet to go as far as running slicks for the full benefit.

Still in the paddock,
Fozzie

[Paul]

Tread is effective in puddles, and you would need impossibly huge amounts of energy pumped into the tyres to evaporate puddles at the speeds they're going.

[hollus]

The tire has a circumference somewhere about 2 m long. A car at 200km/h is covering some 60 meters every second, that's 30 revolutions of the tire every second. If a part of the tire is in contact with the track for, say, 20 degrees of the revolution, that means that a particular piece of tire is in contact with the asphalt for about 2 milliseconds at a time (wow!). Not enough time for much evaporation (or boiling).
In any case, if you were to succeed in making the hot tire "boil" any significant amount of water from the contact patch, I think you'd get this:

Essentially an air cushion between the car (and water) and the track. As obvious from the video, not very good for grip.

Edit: circumference corrected.

[Reckoner]

Fozzie,

Without doubt this is the type of cutting edge thinking we require in the paddock. This is without doubt so simple but at the same time a theory which is already going deep through proto & test and has the potential to give a HUGE edge during wet sessions.

The key is to find the right molecular properties which allow maximum traction yet allow the tyre to remain in a solid form in the sense of simple physics.

A few P&T depts claim they have generate a new class of physical form. Not a solid yet not a liquid a Solquid.

Keep it coming Fozzie you are at the pinnacle of advanced development.

[Hotforwords]

Fozzie,

What a great question to the forum! Having been an avid reader for some time now, I felt compelled to comment on this thread.

Theoretically this is would work but, there are so many factors acting as variables, such as the temperature of the water at air/water surface, the humidity of the air and the temperature of the surrounding air.

I guess the hardest part of the theory would be how the tyres would create its almost solar flaring effect to both evaporate the surrounding water and heat the contact surface ahead of tyre contact.

The advantage this would have in wet weather qualifying would be totally unmatched, you certainly need to persue this.

#aheadofthegame #keepondeveloping

[Fozzie]

Thanks for the input guys, I appreciate the feedback and insight.

Hollus, I know we're talking about huge amounts of energy being required here but these are F1 cars after all and they go extremely fast. With the energy recovery and deployment systems surely these problems are surmountable? I think this is a development path with real value: teams are pouring time and money into improving wet weather performance with increased down force etc. but I think reframing the question in terms of a new and better way to shift surface water could yield never before seen levels of wet weather performance.

[Vyssion]

Essentially, all the different tyres try and do is recover contact with the asphalt. With wet weather tyres, the tread is there to divert the water which is displaced by the mass of the car on the contact areas into the channelling on the tyre surface. Pirelli's full wets I read somewhere could displace around 60L/sec of water at 300 km/h through this method. At those speeds, I'm sure you can imagine, the amount of time that the tyre is contacting a specific point on the asphalt is pretty much negligible.

The idea is cool and I'm sure there are some hydro-thermodynamic effects that are present, but for it to work, you would need to develop a way to heat the water, evaporate it, remove the vapour from the area and then wait for your wheel to drop the 1-2mm down to contact the asphalt all in a very small time period. Water is also a very good heat absorber (I remember something like 4200kJ/L of energy or something or other from Thermodynamics)

In vehicle dynamics terms, for you to have a forward traction, your tyres contact patch needs to be in shear along the longitudinal direction, before "slipping" back to normal (See Picture below), which occurs when the inner part of the wheel rotates much faster than the outer part. This slippage is like the sort of "springing action" that allows you to actually move. To see what I mean, take a look at this slow motion video of a dragster taking off. You can clearly see the slip at around 7-8 seconds in and the differing inner and outer rotation speeds.



If there is water between the road and tyre, this shear slip will occur much sooner since the water will lower the effective friction coefficient of the two materials. Hence why it is much easier to get your wheels spinning in the wet vs. dry.

But yeah definitely an A+ for thinking outside the box mate!!

[PhillipM]

There are some very strange posts on this thread, to the point where I'm wondering if they're duplicate accounts for self-back patting. Especially given the posting records.

The amount of energy you would need to boil the water out of the way would be insane, water requires huge amounts of power to boil off, and if you're doing 190mph down the straight, your tyres are encountering a lot of water. That's before you even get to the issue of the steam generated in your contact patch lifting the tyre, or the issues with trying to transfer that much thermal energy, that fast, through a rubber contact area which is fairly effective as a thermal insulator.
To get the point across, look at the track drying machines that were at the Austin GP - they're jet turbines mounted on trucks with the red hot exhaust gases blasting across the track, and they barely make a dent in terms of drying through heat alone, the main thing they're used for is just to push puddles and streams over onto the grass by virtue of the airspeed.

It's a nice thought, but not practically usable, once you got to the point where it was (damp/almost dry tracks), then the small amount of water is displaced into the tarmac surface rather than the tread anyway and the cars are already on slicks.

[Vyssion]

There are some very strange posts on this thread, to the point where I'm wondering if they're duplicate accounts for self-back patting. Especially given the posting records.

If this was directed at me, Fozzie's forum join date and post number are pretty much brand new. I figured a "nice idea" was a gentle way of saying "no.... not at all" since no one joins a forum to be blasted on their first post

But regarding a couple of the other accounts that have posted, yeah, I'd tend to agree with you there!

[PhillipM]

There are some very strange posts on this thread, to the point where I'm wondering if they're duplicate accounts for self-back patting. Especially given the posting records.

If this was directed at me, Fozzie's forum join date and post number are pretty much brand new. I figured a "nice idea" was a gentle way of saying "no.... not at all" since no one joins a forum to be blasted on their first post

But regarding a couple of the other accounts that have posted, yeah, I'd tend to agree with you there!

No, at the other accounts, they're all his alts along with a couple of others by the look of it