2012 US GP - Circuit of the Americas

[strad]

I thought blankets were limited at something like 70°C?

Are they? Is that by rule? Seems like it would be silly to have blankets that don't get to the temperature you want. I personally haven't bought or made any so I can't say that I know for sure. For some reason the number 100C sticks out in my memory.

I still think the "not enough heat in the tires" line gets used for too much in general... particularly in this case when there's a slick track.

I thought there was a specified temp but all I find is this

12.7.3 The only permitted type of tyre heating devices are blankets which use resistive heating elements. The heating elements may only act upon the outer tyre surface.

[SamH123]

So surely they are going to try and clean the track a little?

If it's as bad as they are all saying that could be interesting if all even grid slots lose places. Not at the front of the grid though - Vettel will find the handy cushion of Webber in 2nd and that raceday beast of a merc in 3rd

[raymondu999]

[youtube]http://www.youtube.com/watch?v=aQobFVk-6jA[/youtube]

[raymondu999]

Lewis said something in a TV interview that was interesting - he said that there were certain corners which were just so low grip - but once you got on the power, suddenly the grip was there. Shows you just how good the exhausts are becoming once again.

[strad]

he said that there were certain corners which were just so low grip - but once you got on the power, suddenly the grip was there.

As I understand it they are having problems getting the tires up to temp, So when they get on the throttle the tires heat up that bit more and react well to it?? Whaddaya think?

[raymondu999]

Possibly. But I don't think it will be that instantaneous - though I'm no tyre person. JT has already said he doesn't think tyre temp is the real culprit.

In my personal view I think it's that getting on the power gets the exhaust gases flowing, which then increases your downforce.

[Jersey Tom]

So surely they are going to try and clean the track a little?

I don't think it has anything to do with the track being "dirty." Brand new pavement needs time to cure, and needs hard laps on it to "break it in" as it were.

If they still have exhaust tied to aero my gut feeling would agree with Raymond in that there's where the extra grip is coming from. Otherwise you'd have massive "grip" on entry where the braking torque is far higher than anything you put down with the engine.

Seems like a typical new track / slick, low grip feel to me.

[CHT]

I am just hoping the Wdc won't be over after the first corner. Has anyone Analyzed the long run pace during fp?

[raymondu999]

I usually do - but I didn't really bother this time given that evolution would be massive over the weekend

[raymondu999]

Transposed from the Japanese GP thread

As for asphalt, when it is first laid it has a smooth surface formed by the rollers. As the traffic runs over the new surface it wears away the soft binder (bitumen) and filler (fine aggregates). The result is that the hard coarse aggregate (ie stones) are left standing proud. That's the optimum texture for tyre friction.



Then as further traffic passes over the surface it wears down the aggregate, and the sharp arises (corners) of the aggregate are worn to rounded edges. Hence the overall "friction" goes down.

Depending on traffic and climatic conditions, the optimum roughness is roughly 1 year, then the roughness trails off over 10- 20 years.

So that's why a new asphalt looks smooth, and old asphalt looks rough. They both looked the same when new.

Incidentally, surface friction is measured by a pendulum that skids across the surface to mimic a skidding car tyre. Here's a portable version, they can also be truck mounted for checking long stretches.

[youtube]http://www.youtube.com/watch?v=sctWKuk1qk0[/youtube]

You can also measure the degree of roughness using lasers, or traditional sand patch test

[youtube]http://www.youtube.com/watch?v=jOYNVZa0Vew[/youtube]

Well, as I told you, wisdom points to say "I don't know" when you don't know. I have no idea.

Grip depends on surface roughness more than on the age of pavement, although age comes in a close second place. Age effect depends on hardness of aggregates (rocks). So, I have no idea.

There is a simple test to measure skid resistance of asphalt, unless we can find those test numbers (that you run as a matter of routine when resurfacing a race track) then that question is unanswerable.

Of course, you could find before/after pictures to answer "generally" (which means you are speculating and your answer is worth little). If you see the same texture, then more grip. If the texture is more closed (smaller stones), is anybodies guess. If the texture is more open (bigger pores/larger stones) then definitely, more grip.

Usually you are careful not to change texture as more grip means more tyre wear. Nowadays this is a balance that is bringing white hairs to many team tyre expert's heads.

A part of the larger grip of new asphalt comes from the asphaltenes/maltenes issue: asphaltenes are long polymers, maltenes are shorter. UV radiation (sun light) breaks asphaltenes in asphalt and convert them into maltenes. Asphaltenes are stickier, so older asphalt offers you less grip.

Dust also embeds itself into asphalt diminishing grip (if dust comes from clay, but you could have sand dust in dry/cold places that would increase grip).

However the largest effect on grip, after the breakup of asphalt through sunlight damage, comes from a smoother surface (this could be more important than anything else): the less bumps and jumps you have, the larger grip you have (and much better acceleration) because the suspension is not working. Have you seen how the wheels move on Korea's kerbs? That.

[siskue2005]

Webber is under FIA investigation for for missing a weight check in qualifying (Q1,12:19 local time).

what i saw them roll his car to FIA garage in Q1!
i will get the pic from my PVR
here is the pic, they are rolling him into the FIA weighing area

"The driver failed to proceed directly to the FIA garage for weighing when signalled to do so," said the stewards. "However upon realising the error, the team brought the car back to the FIA garage immediately."

http://www.autosport.com/news/report.php/id/104346
so the pic shows they brought him back at the end of Q1

[Raptor22]

Transposed from the Japanese GP thread

As for asphalt, ...

The type of bitumen used plays a massive role in the overall available friction as well. Surface roughness will determine the surface area a tyre has to conform to but the Bitumen provides the available ccohesive properties for molecular interaction between tyre and tarmac.

[raymondu999]

Regarding Webber's travails with the weighbridge, apparently what also played a part in reducing the repercussions to a reprimand was that the crew realised immediately and rolled him to the fia straight off. Or some such.

[stefan_]

I like the fact that Lotus seemed to be under the radar the whole weekend. Doing their thing, not pushing very hard and they eventually did a 4-5 qualifying which is great if you ask me. Hope that Grosjean keeps his cool in 9th.

[Raptor22]

I think Grosjean is going to play with Nando today.