Today's Spanish Grand Prix has clearly been dominated by tyre degradation, and in the case of at least one team (Mercedes) I would speculate that they have been undone because of an inability to keep tyres in the designed operating window.
Which makes me wonder ... what exactly are the techniques that can be used to manage tyre degradation ?
Firstly - what are the key factors that need to be controlled ?
Pressure, surface temperature, maximum surface shearing force, min/max dynamic axle load ?
Secondly - what are the control mechanisms available ? Are there specific technologies deployed e.g. controlling the degree of brake heating that is allowed to affect the tyre. Looking through the technical regs I see that no heating devices other than the blankets are permitted, but I can see no rule disallowing cooling devices. Are things like this deployed ?
I am quite new to this technical forum, and have no specific background in F1 technology so would be genuinely interested in any response.
This is a very good question, but it is also a very, VERY broad one. The short answer is that there is no universal answer to this question, if there were it would be much easier to control and we wouldn't see the teams struggling with it. I will attempt to give you some form of answer, but I hope that others will build on it and improve it because I certainly don't possess enough knowledge to give a complete answer.
Ok so your first question: what variables do we need to control? Again, bearing in mind that there is no single answer to this, pressure and surface temperature are certainly two very important factors, as is maximum sheer force. Other factors include the stiffness of the vehicle suspension, its weight distribution, the height of its centre of gravity and driving style.
Obviously that list by itself doesn't tell you a great deal, so here is some explanation: the objective of the driver is to get as much grip out of the car as possible, whilst protecting his tyres as best he can. Many of the factors which benefit a fast lap time cause tire degradation. There are however ways to drive at an optimum between the two, and to explain that you need to understand that tyre forces come from two sources: the chemical and mechanical adhesion of the tyre contact patch to the road, and the physical deformation of the tyre out of its natural line of rotation (ie if we drew a line straight down the middle of our tyre and watched it, near the contact patch we would see it deviate out of line then fall back in line). At low levels of grip, the majority of our grip comes from this deformation; at higher levels of grip the majority comes from adhesion. Every tyre is designed to operate at a desired temperature at which it produces peak grip, but beyond which the tyre surface thermally degrades. If we drive near the limit of the tyre, but don't cross over it, we get the most out of our tyres.
Unfortunately doing that is very difficult: even on a single tyre you are going to have non uniform temperatures and your shear stresses are going to vary, but if you keep these factors as uniform as possible you are going to do better. Now if we consider all four tyres, if we load them all equally in a corner, we will get the most grip for the least degradation; this is not possible because the centre of gravity causes a moment which rolls the mass out onto certain tyres due to a D'Alembert force. But again, certain driving styles and vehicle designs will limit this, some more than others. A stiffer suspension setup will limit it more, and an optimum tire pressure will help too. The optimum tyre pressure is one which doesn't over-inflate the tyre so much that the contact patch is reduced substantially, but doesn't under-inflate it so much that its just floppy and there is no real stiffness to it.
As far as control mechanisms go, there are a few. One problem that F1 cars have is getting enough heat in the tyre for qualifying but not too much for the race. Controlling the degree of brake heating is difficult, but a few years ago McLaren had a little slider that a mechanic could flip to limit how much heat was vented out onto the tyre if I remember correctly. There haven't been any cooling systems that I can think of in recent times, certainly nothing relating to fluid cooling. So what CAN they do? Brake bias is a biggy, they can shift that around to try and control tyre temperatures certainly. Differential control is another one, three of those big dials on an F1 steering wheel relate to the differential and an extension of that is if your differential is locked you will get tyre spin in the corners which will heat your tyre up a lot and tear the surface of the tyre too. Locking your tyres or spinning them up are two very bad factors for tyre degradation.
I can't think of much else off the top of my head. Sorry, its a bit rambley, the truth is that it is very difficult to answer. Hopefully someone else will come along and give you a better answer.
How much does this limit what teams can do with the tires?
4.2 Weight distribution :
For 2012 and 2013 only, the weight applied on the front and rear wheels must not be less than 292kg and 343kg respectively at all times during the qualifying practice session.
If, when required for checking, a car is not already fitted with dry-weather tyres, it will be weighed on a set of dry-weather tyres selected by the FIA technical delegate.
The answer is much easier to give if you put it in context of the preceding rule:
4.1 Minimum weight:
The weight of the car, without fuel, must not be less than 642kg at all times during the Event.
If, when required for checking, a car is not already fitted with dry-weather tyres, it will be weighed on a set of dry-weather tyres selected by the FIA technical delegate.
Rule 4.2 specifies a weight of 635kg which only gives you 7kg to play with if you want to satisfy both rules and hit the minimum weight limit. There are however a couple of things I imagine a team could do if they wanted to: 1) these weight rules apply to the car's dry weight; if you wanted a certain weight balance on higher fuel loads I don't see why you couldn't place your fuel tank forwards or aft of the dry centre of gravity to suit your needs; 2) the much bigger concern will be CG height - when you have a car that can easily pull 2g in a fast corner and can brake at 5g, the shifting of weight around your car becomes really significant. If you watch some of the lower classes of racing like the Clio Cup then you will see the cars go up on three wheels a lot - its the result of lack of chassis and suspension stiffness that the car can get a wheel off the ground like that, but its really the high centre of gravity that is to blame for it happening in the first place.
Increasing raw weight is going to affect your acceleration forces, both lateral and longitudinal, because tyres produce less force per unit weight we load them and fundamentally every turning and acceleration force the car produces has to go through the tyres. Obviously that is a bad thing and teams will want to run at as low weight as they can.
However, if we were to take our car and we used some super special material that doesn't exist but is really dense and we lined the floor of our car in this material so that we doubled its weight, we would approximately halve the height of its centre of gravity and we would halve the amount that the rolling affect we saw. The transfer of absolute weight would be the same because we have halved the distance but doubled the weight, but the relative increase in weight on the outside wheels and decrease on the inside wheels would be smaller which means that our tyres would be more evenly loaded and that is better for grip and less degradation. Obviously we have just doubled the weight of our car and in doing so we halve the effectiveness of our aerodynamic package (the force is once again the same as with the lighter car, but the acceleration is halved as our weight has doubled and F=m.a). My point is not that doubling the weight would be a good idea, it wouldn't be, its more that all of this stuff is interconnected and its difficult to isolate the affect of one change.
So short answer: it doesn't really LIMIT anything, because if a team really had that bad degradation they could move some ballast around and take the weight penalty associated with it, but its not something that they would want to do. In reality they only have 7kg, or about 1% of dry weight to play with which isn't a lot. But the fact that this is dry weight means they can place the fuel tank where they like - I imagine their are some restrictions on its placement but I would be surprised if you can't move it a little bit this way or that, and when you are shifting 100kg of fuel just a little bit you get a significant affect on a 600kg car.
Last edited by thepowerofnone on 13 May 2013, 18:11, edited 1 time in total.
It should be noted that a 2009(?) Lotus car was used to test and perfect the Pirelli compounds so its not much of a surprise that they do well on them. Teams tend to follow certain design ethoses under certain managers and so one would expect the old car to share a lot of similarities with the new one.
thepowerofnone wrote:It should be noted that a 2009(?) Lotus car was used to test and perfect the Pirelli compounds so its not much of a surprise that they do well on them. Teams tend to follow certain design ethoses under certain managers and so one would expect the old car to share a lot of similarities with the new one.
it should be noted that R30 didnt have FRIC, it had also both push-rod suspension, it didnt have coanda exaust, etc. which is exact opposite of Ferrari who win race, or Lotus E21 who dose not have nothing similar with design R30, because from R31 they created new revolution car, which is E21 evolution.
You are have the power of none, or arguments to discuss or make point.
Urg... Please don't assume that just because you switch the direction of your push/pull rod, introduce a FRIC system or change from a blown diffuser to a coanda exhaust that you dramatically change the ethos behind how you want your car to be set up and function. Things that you could say about every Red Bull: they are designed to run higher downforce and higher drag than their rivals; they were designed by a very similar group of people; their design is optimised to suit Vettel's very specific driving style.
Yes, well done, you have established that in four years Renault became Lotus and their car has been developed somewhat over that time. However, if you were working for that team and knew that your car from a few years back was being used to optimise the tyres for the coming year, given you have access to every single CAD drawing and calculation/simulation used to model that car's behaviour, you would be a complete moron to think "we have all this data on how Pirelli are likely to optimise their tyres, but let's not use it because this year we want to push front tyres out rather than push them in and that completely changes EVERYTHING!"
I am not saying that their car is identical to the testing car, or that it is the only reason which they are good on their tyres, but Lotus aren't the only team to have FRIC, Mercedes has it to so I suppose you are right: FRIC clearly always gives excellent tyre preservation qualities.
thepowerofnone wrote:Urg... Please don't assume that just because you switch the direction of your push/pull rod, introduce a FRIC system or change from a blown diffuser to a coanda exhaust that you dramatically change the ethos behind how you want your car to be set up and function. Things that you could say about every Red Bull: they are designed to run higher downforce and higher drag than their rivals; they were designed by a very similar group of people; their design is optimised to suit Vettel's very specific driving style.
Yes, well done, you have established that in four years Renault became Lotus and their car has been developed somewhat over that time. However, if you were working for that team and knew that your car from a few years back was being used to optimise the tyres for the coming year, given you have access to every single CAD drawing and calculation/simulation used to model that car's behaviour, you would be a complete moron to think "we have all this data on how Pirelli are likely to optimise their tyres, but let's not use it because this year we want to push front tyres out rather than push them in and that completely changes EVERYTHING!"
I am not saying that their car is identical to the testing car, or that it is the only reason which they are good on their tyres, but Lotus aren't the only team to have FRIC, Mercedes has it to so I suppose you are right: FRIC clearly always gives excellent tyre preservation qualities.
I dont want to argue with you because already is somewhere very similar discussion (maybe on autosport.com forum) where it shows you are wrong, so wasting time for me to write again same thing.
I personally don’t believe that exist a technique that can be used to measure the degradation level …unless they allow you to put something in the tyres.
the answer is simple but not that easy to accomplish:
you got a finite number of tyres allocated and you need to make the most of them .
This starts with :How many laps and how hard do you lean on the tyres you need for the race in qualy.
It goes on with how you prepare the tyres for race day -tyre preheating process.
and it goes on with how you set up the car -given your base does even allow for a successful setup.
and finally Do not overdrive!
With tyres on flames you will not produce more grip but certainly heat -and even if some think you need heat to make a tyre work it is the other way round .The tyre does release heat when worked hard.
This is the main issue to understand for the teams .At which slip angles under which load does the tyre produce the best lateral grip and have this happen at all four corners synchronized in a driver controllable way.
So if your car does pitch and roll a lot this does translate into varying vertical loads -and under differnt vertical loads the tyre wants different slip angles to produce best grip
Then :you could be slightly overboard with slipangles on one end of the car and slightly under at the other end -resulting in a balanced car behaviour -but only for a lap or two....as one end will get hotter and the other cooler this will result in ever more understeer ,so the driver is changing his style to make the rears slide more but this will not bring back the fronts and so the compensating spiral will just kill the tyres in no time.
If anyone thinks this sounds familiar ..it is no coincidence..It sure is a fair bit more complicated to solve but in essence they abuse the tyre .
and as we have seen driving slow does not really help the matter ,as your temps drop like a stone and you have no grip at all and it basically is no different to overdriving and pitting more often.
Anyone who ever explored the limits of adhesion on a racetrack will be aware of the fact a car can be quite easily manipulated towards over or understeer by driver inputs ...but as you manipulate the line to draw is quite fine when it comes to overdoing things.
Last edited by marcush. on 13 May 2013, 20:48, edited 1 time in total.
Dragonfly wrote:Currently it seems there's only one technique - drive as slow as the optimal lap time which is expected to provide a x-laps stint.
it's obvious this isn't working, mercedes and red bull showed it. hamilton team radio and rosberg confirmed it. first
hamilton tried preserve tires but he was too slow (as he can't drive slower) and didnt preserve tires and on end of race rosberg get from team radio order to push car on maximum, and he was faster and didnt preserve it. so it was the same driving fast or slow. this showed that pirelli dont have nothing to their performances, tires will run out in same case ones maybe faster then other but same. From this you can realistly conclud it's just question of car design and his setup window. Trough him extract performances and keep tires in their working window. Some cars can hit that window multiple time, some certainly dont, 3rd year in row...
Dragonfly wrote:Currently it seems there's only one technique - drive as slow as the optimal lap time which is expected to provide a x-laps stint.
it's obvious this isn't working, mercedes and red bull showed it. hamilton team radio and rosberg confirmed it. first
hamilton tried preserve tires but he was too slow (as he can't drive slower) and didnt preserve tires and on end of race rosberg get from team radio order to push car on maximum, and he was faster and didnt preserve it. so it was the same driving fast or slow. this showed that pirelli dont have nothing to their performances, tires will run out in same case ones maybe faster then other but same. From this you can realistly conclud it's just question of car design and his setup window. Trough him extract performances and keep tires in their working window. Some cars can hit that window multiple time, some certainly dont, 3rd year in row...
Or ask Lotus and 9 other teams 
