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 Post subject: Tyres
PostPosted: Thu Oct 11, 2012 4:16 pm 
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Joined: Thu Jul 21, 2011 12:17 am
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Hi guys, I'm not a very technical person but I do like to understand F1 as much as I can and at the moment I'm concentrating on tyres. I've been trying to find information about the current Pirellis and the other tyres that have been used in F1 for the last ten years.

What I'd like to know is what are the differences in characteristics of the 2011-2012 Pirellis, the Bridgestones and the Michelins (stuff like sidewall construction etc). Thanks to anyone willing to help :-P


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 Post subject: Re: Tyres
PostPosted: Fri Oct 12, 2012 1:10 pm 
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Oh boy, you started out in the wrong place as this is potentially the most difficult aspect on the car.

Tyre construction and compounds is normally labelled as "black magic" as they are mostly stuff that companies know they work after a lot of development and research on materials and compounds and is not really the kind of information they share as to not let competitors know what they are doing.

I have worked on tyre analysis before but that was more analysis than design as to know how to get the tyres working and how to design/tune the suspension/aero/differential/brakes and such and such work included using tyre data extracted from a test facility and filtering them and analyzing them to make design decisions and a vehicle model and after that to make adjustments (unfortunately we finished the car a bit too late for that).

If that is the kind of explanation you are looking for i could give you a few simple tips


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 Post subject: Re: Tyres
PostPosted: Fri Oct 12, 2012 3:57 pm 
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M.Nader -DODZ- wrote:
Oh boy, you started out in the wrong place as this is potentially the most difficult aspect on the car.

Tyre construction and compounds is normally labelled as "black magic" as they are mostly stuff that companies know they work after a lot of development and research on materials and compounds and is not really the kind of information they share as to not let competitors know what they are doing.

I have worked on tyre analysis before but that was more analysis than design as to know how to get the tyres working and how to design/tune the suspension/aero/differential/brakes and such and such work included using tyre data extracted from a test facility and filtering them and analyzing them to make design decisions and a vehicle model and after that to make adjustments (unfortunately we finished the car a bit too late for that).

If that is the kind of explanation you are looking for i could give you a few simple tips


Oh no, this is the last piece of the puzzle for me, I already looked at everything else. I'm just really interested to know about sidewalls and all that stuff, the difference between Bridgestones and Michelins and now Pirellis. A simple explanation of that would be great :?


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 Post subject: Re: Tyres
PostPosted: Sun Oct 14, 2012 7:05 pm 
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Joined: Sat Aug 27, 2011 11:00 pm
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Sorry for not responding quickly enough i was just a tad busy. I'll tell what i think you want to know, but in case i blabber about something irrelevant to your question please tell me so :D

When you think about it, it is not the tyre that is the only contact between the car and the ground, even less it is only the contact patch! and so many thought has been put to study what goes on in there in different cases.

At the contact patch forces come in mainly 3 directions: lateral force (cornering), Longitudinal force (acceleration and Braking) and the Car's load pushing down (which in F1 is variable because of the aerodynamics). Now there are also 3 moment forces around each of the 3 axis (X-Y-Z) and it is basically these moments that the driver feels for example a self aligning moment is created when the driver steers the tyres and this moment tries to correct the tyre back to its original state and as this goes to the driver through the steering tie rods and depending on the change in that load he knows where near the limit he is (other factors also go into this but i am simplifying things a bit).

when you ask the tyres to corner (i.e you need lateral force) the tyres produce a slip angle at the contact patch, and a simple explanation is that the slip angle is the difference between where the wheel is pointing and where it is heading, and this is caused by a deformation in the wheel structure. Theoretically slip angle is a bad thing as it deflects the car from its path, but there is no force without slip and no slip without force, and really no one knows which causes the other.

Here is how the tyre looks when loaded
Image

From what i know, F1 cars' tyres reach maximum force at around 2.5-3 degrees of slip which is very low but having it that way reduces the energy lost in the tyres but will need ultra sensitive drivers to understand what the car is doing, in any other series you will see tyres that reach peak loads at double these values for the novice drivers to get a feel for them.

Now to answer your question for the differences between each supplier, is very open and i will thus tell you what i can only guess.

The company chooses the shape, profile and compounds for their tyres to adjust their durability and deflection (slips) and thus reactions to forces. Now if you remember during the Michelen starting from 2003 onwards had a more "square" tyre than Bridgestones and this was a negative as they created more aerodynamic drag because of their shape but however their tyres were designed in such a way that their slip angle operation range, camber sensitivity (due to a wider contact patch from the squarer shape) and reaction forces and tyre contact patch deflections (which translate to sidewall deflections) were much better than that of the more round/aerodynamic Bridgestones. I don't really recall the compounds they used to make the rubbers and the durability differences so i won't comment on that.

Now for the current Pirrelli tyres they load reactions are not really strictly determined but i would say that with tough loading they can't reach 5G forces but much less than that to 4.5G under braking and a maximum of 4G cornering. That is what i could understand from the driver's onboard.
But the area in which they fiddled more was the tyre materials and stiffness, they have used more artificial compounds to make the tyres other than just plain rubber and thus they have more control on tyre durability and stiffness:
in F1 cars more travel is in the tyre than in the suspension! (in case of bumps or roll and steer) and thus having tyres with very different stiffnesses will lead to having to adjust the car's balance so that the driver has the balance he needs to drive the car the way he likes (oversteery or understeery) and that is why now you can have a car that is fast on one compound and slow on the other as the whole car stiffness is changed from changing tyres.

Durability is what they had more in mind though, with these artificial compounds they could manage how the tyre wears and degrades and thus they could look to set a target of pitstops per race and make a compound that will slowly go away till a certain point where it is virtually useless after that (as you could hear Vettel's engineer telling him on the radio today, although it was all bogus in the end). Also these tyres are very temperature and pressure sensitive and Pressure is temperature IS also pressure sensitive and thus getting these tyres to their operating temps and pressures has been crucial this year, get them too hot and they have lower grip and wear, get them too low and the same happens and if you try to correct that you will overshoot and get them too hot!

Well that is as simple as i can put it, i hope this answers your question.

Very tough being an engineer in F1 isn't it! :lol:


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 Post subject: Re: Tyres
PostPosted: Tue Oct 16, 2012 10:35 pm 
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Joined: Thu Jul 21, 2011 12:17 am
Posts: 114
M.Nader -DODZ- wrote:
Sorry for not responding quickly enough i was just a tad busy. I'll tell what i think you want to know, but in case i blabber about something irrelevant to your question please tell me so :D

When you think about it, it is not the tyre that is the only contact between the car and the ground, even less it is only the contact patch! and so many thought has been put to study what goes on in there in different cases.

At the contact patch forces come in mainly 3 directions: lateral force (cornering), Longitudinal force (acceleration and Braking) and the Car's load pushing down (which in F1 is variable because of the aerodynamics). Now there are also 3 moment forces around each of the 3 axis (X-Y-Z) and it is basically these moments that the driver feels for example a self aligning moment is created when the driver steers the tyres and this moment tries to correct the tyre back to its original state and as this goes to the driver through the steering tie rods and depending on the change in that load he knows where near the limit he is (other factors also go into this but i am simplifying things a bit).

when you ask the tyres to corner (i.e you need lateral force) the tyres produce a slip angle at the contact patch, and a simple explanation is that the slip angle is the difference between where the wheel is pointing and where it is heading, and this is caused by a deformation in the wheel structure. Theoretically slip angle is a bad thing as it deflects the car from its path, but there is no force without slip and no slip without force, and really no one knows which causes the other.

Here is how the tyre looks when loaded
Image

From what i know, F1 cars' tyres reach maximum force at around 2.5-3 degrees of slip which is very low but having it that way reduces the energy lost in the tyres but will need ultra sensitive drivers to understand what the car is doing, in any other series you will see tyres that reach peak loads at double these values for the novice drivers to get a feel for them.

Now to answer your question for the differences between each supplier, is very open and i will thus tell you what i can only guess.

The company chooses the shape, profile and compounds for their tyres to adjust their durability and deflection (slips) and thus reactions to forces. Now if you remember during the Michelen starting from 2003 onwards had a more "square" tyre than Bridgestones and this was a negative as they created more aerodynamic drag because of their shape but however their tyres were designed in such a way that their slip angle operation range, camber sensitivity (due to a wider contact patch from the squarer shape) and reaction forces and tyre contact patch deflections (which translate to sidewall deflections) were much better than that of the more round/aerodynamic Bridgestones. I don't really recall the compounds they used to make the rubbers and the durability differences so i won't comment on that.

Now for the current Pirrelli tyres they load reactions are not really strictly determined but i would say that with tough loading they can't reach 5G forces but much less than that to 4.5G under braking and a maximum of 4G cornering. That is what i could understand from the driver's onboard.
But the area in which they fiddled more was the tyre materials and stiffness, they have used more artificial compounds to make the tyres other than just plain rubber and thus they have more control on tyre durability and stiffness:
in F1 cars more travel is in the tyre than in the suspension! (in case of bumps or roll and steer) and thus having tyres with very different stiffnesses will lead to having to adjust the car's balance so that the driver has the balance he needs to drive the car the way he likes (oversteery or understeery) and that is why now you can have a car that is fast on one compound and slow on the other as the whole car stiffness is changed from changing tyres.

Durability is what they had more in mind though, with these artificial compounds they could manage how the tyre wears and degrades and thus they could look to set a target of pitstops per race and make a compound that will slowly go away till a certain point where it is virtually useless after that (as you could hear Vettel's engineer telling him on the radio today, although it was all bogus in the end). Also these tyres are very temperature and pressure sensitive and Pressure is temperature IS also pressure sensitive and thus getting these tyres to their operating temps and pressures has been crucial this year, get them too hot and they have lower grip and wear, get them too low and the same happens and if you try to correct that you will overshoot and get them too hot!

Well that is as simple as i can put it, i hope this answers your question.

Very tough being an engineer in F1 isn't it! :lol:


Thanks very much for the answer, it's exactly what I needed :-P


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 Post subject: Re: Tyres
PostPosted: Mon Oct 29, 2012 3:56 pm 
http://www.youtube.com/watch?v=J6DMnQcqYTM

http://www.youtube.com/watch?v=J2-ToHXNwrM&feature=related

http://www.youtube.com/watch?v=rh8-5zyxUE4

http://www.youtube.com/watch?v=qG3sdF8IXyA


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 Post subject: Re: Tyres
PostPosted: Tue Oct 30, 2012 11:20 pm 
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Joined: Thu Jul 21, 2011 12:17 am
Posts: 114
Blinky McSquinty wrote:

Thanks, I've not seen some of this stuff before :thumbup:


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 Post subject: Re: Tyres
PostPosted: Mon May 27, 2013 7:31 am 
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Joined: Thu Mar 22, 2012 12:00 am
Posts: 508
I'm wondering if anyone can comment on this year's steel belt with relation to the delaminations we've been seeing. Is it a direct cause? If I understand correctly, the tyre will deflate normally instead of delaminate without this steel belt.

Also, how does this steel belt affect degradation vs. their polyester/kevlar belts from last year?


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 Post subject: Re: Tyres
PostPosted: Mon May 27, 2013 7:15 pm 
One of the major issues with the 2012 tire was blistering and graining. This problem is localized heating, and the steel belt was designed in to help spread the heat evenly across the tread.

For some reason the tire rubber does not adhere to the steel belt as well as the previous kevlar belt, and we saw some treads separating from the steel belt.

I believe that the steel belt did a good job spreading the heat across the entire surface of the tire, contributing to longevity. With no steel belt, there can be localized heating, resulting in blisters.


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