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PostPosted: Sat Nov 24, 2012 8:20 am 
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I was reading this article
http://en.espnf1.com/f1/motorsport/story/95527.html

I was hoping some expert could tell me how a tyre can effect the aero balance of a car : ) ?


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PostPosted: Sat Nov 24, 2012 12:14 pm 
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I think you posted the wrong question (or wording)

The F1 tyre has a certain stiffness as a constructed tyre along with the wheel, and it adds to the suspension stiffness (more like decreases).
The balance drivers like is divided into 2 sections: Mechanical and Aero.

The mechanical section is where the tyre have the most effect, in F1 the tyres deflect just about equal to the suspension (yes, the suspension is that stiff!) so tyre spring rates are very important during different loading conditions as the relation is not linear unlike what springs should be.
The combination of Tyre, Spring, and antiroll bar determine the car's mechanical balance which is adjusted to suite the driver and car, so having tyres whose stiffness changes a lot, or front quite a bit different than the rear will cause some teams problems setup wise.

In terms of Aerodynamics this story changes a lot, more aerodynamics will mean that the tyres can produce more Gs but then what Pirelli could have done is that they made the tyres wear out, degrade or overheat when loaded more than a certain amount. or even more they could have made them sensitive to load applied, so that basically more load on them would decrease their coeffeceint of friction drastically so teams will need to be careful when selecting downforce settings (which will also be a factor in the mechanical section where weight transfer is quite noticeable)


I am just guessing but these are my most likely guesses and conclusions i have reached after yesterday. Given that these tyres were faster than the 2011 Spec, have a broader operation range but overheat quickly and thus wear out i am very excited for next year


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PostPosted: Mon Nov 26, 2012 12:25 pm 
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So the 2013 tyres will basically be more sensitive, wear out quicker on higher downforce load, So the teams would have to put low downforce wings/setup on their cars dodz ?


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PostPosted: Mon Nov 26, 2012 3:57 pm 
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Due to the immense forces the tyres go through spinning so fast, the width of then alters slightly at speed. Also some tyres bulge out the side more than others. This will affect air flow around and over tyres meaning a change in the cars overall air flow.

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PostPosted: Mon Nov 26, 2012 4:37 pm 
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There are so many ways tyres can affect aero I think even experts struggle to consider them all.

As I am at a loose end, I thought I would post here, not with the intention of stating 'this is what happens' because I am no expert, but as a sounding for us mere mortals to chew it over.

Some of what I say will be just my interpretation of it, or even plain misconception, so please correct anything yo have issues with, but in a fashion that adds to the discussion, not just 'you are talking crap'. 'You are talking crap because.... ' is fine though

The bits I will try to add.

Tyres affect ride height, which affects handling. The 'softness' of the tyre wall governs how far the center of the hub, and so the floor of the car is above the track. A stiff wall will not deform much when downforce loads the car a soft one will. (ride height changes at speed=affects aero etc)

The rolling radius of the tyre also affects height, and the amount of material that gets removed during its use lowers the car by that same amount. If it is 10mm, a car with a worn tyre is 10mm lower etc.(doubt it is that much though)

The sidewalls flex when the car corners or rides a curb. This in effect puts the rubber in a different place to where it was on the straight. only a tiny amount, but possibly enough to be noticed by aero. A softer wall also allows the centrifugal effect to deflect the tread area too, so it works both ways.

The profile of the tyre affects airflow around it and the car, as to a smaller extent does the texture of it. The tyre is spinning so texture affects the airflow coning off it and reflected by it.

The engineers calculate what they call 'Squish' which is like the air you feel if you clap your hands infront of your face. They try to direct this to their advantage. The profile affects this too

There are several more effects but I couldn't even begin to explain them, so hopefully some one with more knowledge will assist, and straighten out some of the rubbish I have posted.

Keep it civil and we could learn stuff (it wont hurt, it may even be handy :] )

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PostPosted: Mon Nov 26, 2012 8:54 pm 
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Maky wrote:
So the 2013 tyres will basically be more sensitive, wear out quicker on higher downforce load, So the teams would have to put low downforce wings/setup on their cars dodz ?


Well basically that is my guess yes.

Sensitive in terms of load applied, not operating conditions. In fact going by what Perelli are saying they will operate at broader ranges in terms of pressure and temperature.

Wear out quicker, i am only guessing. no idea if that is true or not but that was what i could judge after FP1 but then again the cars were not suited to the tyres so wear may have been exaggerated. but on their 1st timed laps they were a bit quicker than the 2012 spec tyres with the same downforce levels. so more probably a mechanical set up issue.


@moby

I think all of what you wrote is correct, but i just don't see those parameters as major changes at all. I may be wrong as i really don't know what Perelli have in store.

Tyre induced drag: the front wing should have 90-95% of that covered so that the wheels don't induce much drag at all. if However the wheels are thinner then the wings will also have to be shorter and thus produce less DF. but given how they were used with 2012 Spec wings i don't see that happening. and given how Perelli have been criticized for their tyres deflection this year i doubt the tyres will deflect more next year, if anything the tyres will be more rigid with stronger sidewalls.

Tyre deflection: Maybe the way it affects ride height as you said and given that Perelli are looking for more wear this may be true, but then again why didn't this show up in testing in Brazil with cars botoming out?
Also tyres do lose a bit in terms of wear but they also gain a lot of debries (tyres around the track) which stick to them and thus give them basically the same height they had so they don't really lose any height. I don't think any designer will be looking to take advantage of such a risk and unusefull ploy (as it will at max give him 1-5mm) specially that the car is also going up substancially during the races as it gets lighter on fuel so that gain is negligible.


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PostPosted: Fri Dec 07, 2012 11:28 pm 
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I haven't looked at 2013 spec much, but in tyres of generic tyre aero the shape of them has a very large effect on the wake they produce.

You get vortices forming off the shoulders and changing from a rounded shoulder to a square will change where flow separates and which direction these vortices rotate. Then you through in the effects of camber and yaw on this and the wake from different years could be a mile apart.


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PostPosted: Wed Dec 19, 2012 4:45 pm 
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Maky wrote:
So the 2013 tyres will basically be more sensitive, wear out quicker on higher downforce load, So the teams would have to put low downforce wings/setup on their cars dodz ?


No, less downforce means less grip and more sliding. Just watch any car when a wing is knocked off and watch that end of the car slide around. And when any tire slips, it degrades quickly as heat builds up and the rubber is ground away.

Formula One tires and their management is an incredibly complex puzzle. We saw that all last year where some of the brightest minds in motor racing were constantly scratching their heads trying to understand the problems and find solutions. If you increase the load on the tires you can corner better and work them harder. But that produces heat. Too little grip and the tires start to slide,and once again that's a bad place to be in.

Everything is a compromise between ultimate performance and reliability/longevity. That's why some cars had better wear characteristics than others, due to suspension geometry, weight balance, aero balance, power delivery, even driver style. These guys, the engineers and drivers are walking a tightrope. If you can find the "sweet spot" where everything matches up, the car becomes the best in the field. It happened to Mercedes in China. But if just one parameter changes, be it temperature, or humidity, track surface, you name it, anything, then everything changes and the car can fall off the cliff.

That's one of the attractions of Formula One, that it is so freaking difficult.

The 2013 tires will have more sidewall flex. That means that when a car travels over a bump it will ride differently than a 2012 car, maybe just one millimeter. But one millimeter is a huge thing in Formula One, it compromises the suspension and aerodynamic characteristics of the car. So the suspension and aerodynamics have to be redesigned to accommodate and deal with these new car behaviors.


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PostPosted: Wed Dec 19, 2012 5:05 pm 
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Well, most of what you said is true Blinky but then that contradicts with your original statement

Quote:
No, less downforce means less grip and more sliding. Just watch any car when a wing is knocked off and watch that end of the car slide around. And when any tire slips, it degrades quickly as heat builds up and the rubber is ground away.


You can't just keep adding more down force and expect the tyre to perform better as they will overheat.

I reached my conclusion based on the couple of laps the teams did on them during the Brazilian weekend.

Lewis and Jenson throughout the week settled on the highest down force setup they had (conserving the aero balance ofcourse). and yet when they put on the new reg tyres the tyres went hot very, very fast with neither of them locking or anything. They were faster than the current specs but just after the first lap or even in the middle of it both were reporting overheat. with the car not sliding or locking then that must be the load sensitivity!

We know the cars are faster on it so they reward downforce better than the old spec (higher coeffecients of friction), but then again too much will hurt the race as the tyres will start on an accelerated wear rate right after the first lap!

How did you know about the more sidewall flex may i ask?


God, i am glad someone finally posted something in the in depth it has been so quiet of late!


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PostPosted: Wed Dec 19, 2012 7:41 pm 
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I think we're in agreement M.Nader -DODZ-, maybe it's how I expressed myself. Too much downforce and the tires are heavily loaded, they will heat up. Too little downforce and they can slip, leading to overheating and degrading. Like I said, it's a balancing act and the teams have to find the best balance between those two extremes.

I have heard from many different sources about the new tire's sidewalls. Sadly in PF1 where the focus is more on personalities, it's passed over.

Quote:
The walls flex a little more, which will have a significant influence on the aerodynamic performance," he said.


Directly from Hembery.
http://formula-one.speedtv.com/article/f1-2013-pirelli-tires-could-shake-up-pecking-order-hembery-says/


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PostPosted: Tue Dec 25, 2012 12:52 pm 
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Mmm, quite interesting, i can see how that would affect the suspension but Aero seems a bit vague for me.

The endplates would be a bit different on the front wing and sidepods maybe be adjusted but i doubt that this will be major.

if the sidewalls are softer there can be quite some gains from the underbody as well as moby said, but i still doubt it is much.

What are your thoughts about that?


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PostPosted: Sun Mar 03, 2013 10:46 am 
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http://www.youtube.com/watch?feature=endscreen&v=EpFrPqDmOO4&NR=1


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PostPosted: Mon Mar 18, 2013 8:50 pm 
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Hembry's point here is fairly simple once you strip it down. It was rather ambiguous when reading the first ESPN article "deflect more" - in the context (aero) I figured this was "deflect more air" but it seems, after reading the Speed TV article, this isn't entirely the case; he's talking about physical deflection (movement) of the tyre wall... Whilst tyres are inherently a mechanical function of the car (they physically connect the car to the road, as well as providing about 50% of the car's suspension), a LOT of work goes into the aerodynamics of the front wing to best channel air over and around the front tyres as the tyres have a great effect on air flow.

The effect is more pronounced at the rear (as Hembry said) because (I assume) of the difference in tyre sizes and, unlike the front tyres, the rear tyres have comparatively little in the way of airflow management.

So what this means in practice (in the context of aerodynamics) is the ride height is affected - if at a given pressure, the flex on the sidewall is (for arguments sake) double that of last year, you're going to have a greater maximum and minimum travel, thus ride height, (and as we all well know, about 40% of aero comes underneath the car; the lower the car, the more grip) thus a greater differential in maximum and minimum aero grip levels generated by the underneath of the car.

Another very important example is that with greater flex comes a greater change in the airflow coming off the tyres - as the walls expand and contract under bounce and rebound, the airflow changes with this flex (largely down to the change in surface area), and when teams are attempting to, for example, obtain maximum efficiency from the airflow to the diffuser, this increased flex gives a greater change to the characteristics of the airflow in that area of the car.

In practical racing terms - a car going into a fast and bumpy corner will experience a bigger change in aero grip levels as the car bounces over the bumps. Consider the EBD - the difference in aero grip at the rear was greater without the off throttle engine maps, than it was with, and it's this difference the teams need to manage.

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PostPosted: Wed Apr 17, 2013 1:51 am 
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Eveyrone was right:

Tyres get temps quite easily, overheat with more aero load (too less and they don't heat s fast). Flex for quite a bit (not sure of more than previous cars or not) and lose a substantial amount of rubber.

They are also much faster than last year's tyres.

Best minds are on PF1 indeed :)


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