65 replies to this topic

[MarkWill]

Possibly a naive question, but why don't those teams finding it hard to get their tyres up to temperature blow hotter exhaust air over the top of their rear tyres? Is there a rule that prevents this? IMHO it would give a more stable environment for the tyres. I'm sure that the exhaust air is very hot, so you'd probably only want to bleed off some of it over the tyres, and send the rest through a conventional exhaust. Any thoughts on this?

[ray b]

NO
1 warmers pre-heat tyres now before the race and before pit-stops!!!!
2 heat is only needed up to a point, then it hurts if tooooo hi
3 rears only can be spun to warm them if tooo cool at start or on prestart lap
4 no way to heat fronts by you idea=understeer
5 oil in exhaust even a little oil

[Ben]

Getting heat into the tyre is more than a matter of heating the tread surface. When a tyre generates force it is the carcass below that is deforming and heating as well as the tread. You need both and simply heating the tread with the exhausts isn't gonna do this. Also it will (if it has any effect at all) create a balance problem because you can't obviously do the same thing for the front tyres.

There is no substitute for actually working the contact patch adequately to generate the right temerature without overheating the tread.

Ben

[MarkWill]

Hi,

Your replies to date have brought up some interesting points, but I think I have some answers:

re. Ray b - You're absolutely right - oil on tyres would be a problem, so really you would need to have an air-blower, not exhaust gases (maybe use the exhaust gas as a heat-exchanger?.

The overheating issue is a design problem which can be addressed - you don't have to blow all the air over the tyre - and the temperature would be a function of the distance between the air outlet and the tyre (you'd have to design it such that there is sufficient hot air diffused to the atmosphere).

The tyre warmers work at the beginnning, but on a cold track (such as today's San Marino track) they obviously don't work for some teams - the thermal balance between the track and the tyre is working out in the track's favour and bleeding heat off the tyres. Surely this goes for the heat generated by deforming the tyre as well - if the heat isn't kept inside the tyre doesn't it bleed off to the track and ambient air? My thought goes along the lines of - if the ambient air (which must represent a high percentage of the tyre'e environment) is higher, then the ammount of heat lost will be reduced and the tyre temperature will be higher (i.e. stickier). I recognize goes against Ben's comment about working the contact patch, and I don;t mind someone proving me wrong.

[Ben]

Correct me if I wrong, but tyre warmers heat the tyre to the region of 80-90 C whereas the operating temperature of an F1 tyre is in the region of 120-140 C.

I think those numbers are ball park and if so, suggest that tyre warmers are a helping hand and it is the actual generation of a slip velocity in the contact patch that heats the tyres to their operating range. This explains why - despite tyre warmers - cars need a number of laps before they can exploit the tyres full performance.

I think drag racers may use this idea, but I've never seen any hard evidence that it has any useful effect.

Ben

[TomNo]

yes, that can explain why it takes some time to get max grip. anyway, today after qualify practise was RTL introducing with MS new F2002 and he said, that they use aerodynamics to cool rear tyres... i was really surprised! so, heating them is not good idea, i think.

i do not know, what is work temperature of nowadays tyres, but i think two years ago, somebody said 92 degrees of celsia.

[Ross Stonefeld]

The tire warmers must get them very very close to the operating window. I dont think ive ever seen an F1 car exhibit signs of cold tires in qualifying or the race. That they are able to do a fast lap instantly from the pits, definatekly makes me think the tire warmers get them very close to ideal temps/pressures

[MarkWill]

I don't really know what the tyre temps are, but I would have thought that the equation for a "cold" circuit like San Marino is that to get extra grip you need hotter tyres, which in turn means running slightly higher downforce (so that there's extra friction generated, which translates into extra grip). The downside of that is that you lose straightline speed, so you need a power advantage. So my "solution" is aimed at those cars which don't have the power advantage (like the Jaguars or Honda-powered cars) but which still need the extra grip in the corners without sacrificing power, which is also might explain why they couldn't get the tyres to work as well as the Ferrari's (they ran less downforce so the tyres couldn't get as hot as the Ferrari's)

That being said, its the first time I've heard that on today's circuit there were people who wanted their tyres to run cooler, but it does give you a clue about the efficiency of the Ferrari aerodynamic/power package.

Re. Ross - some of the drivers of the cars in todays practise complained that they couldn't get the tyres up to temperature. I believe it was one of the afflictions of last years Jordans as well - they couldn't cool the engine enough, and the tyres (conversely) didn't always get up to temperature (That one's open for discussion though - I'm only quoting what our local tv panel of experts were saying about last years car).

[Jezztor]

I don't think optimum operating temperatues exceed 100 degrees. 94, 95 seems a little more likely, but I stand to be corrected. From what I understood listening to a BAR mechanic a year ago, tyre warmers transfer a slightly higher temperature than the OOT, because there is a slight heat loss when the car is 'coasting' out of the pits.

Jezz

[RDV]

think optimum operating temperatues exceed 100 degrees. 94, 95 seems a little more likely, but I stand to be corrected

ballpark jezztor, difference usually in manufacturers specs for different compound... historically Mich runs tyres with very narrow temperature operating windows, so effectively you will find tread temperatures will be between 80 ~110 , compound optimal could be in increments of 15 deg C(Mich) ,or 20(Bridge). getting tyre temps to optimal and have grip "come in" is down to geometry , usage (driver) and track surface temp.

tyre warmers attempt to get tyres to optimal compound temp, but as front tyres are exposed more than rears and rear tyres can be heated more through use of engine power balance always hard to find, this difference in temp is corrected by driving tyre warmers at higher temp for fronts than rears .

use of exhausts for warming goes opposite real needs , plus oil problems.

...but I would have thought that the equation for a "cold" circuit like San Marino is that to get extra grip you need hotter tyres, which in turn means running slightly higher downforce (so that there's extra friction generated, which translates into extra grip).

...here we are talking about compound optimum temperature , apart from assumed miche vs. bridge temperature optimals, look back to alesis front row start with the Tyrrel alongside Sennas McLaren, at that time Goodyear qualifying tyres were more temp sensitive than Pirelis, and unseasonably cool weather caught Goodyear on the hop, they werent in the correct track temp for the tyres, attempts to warm tyre up by extra downforce involves so much extra downforce ( it works by flexing tyre carcass more..not friction, car effectively slides less ) as to be on the bad side of max/min curve.

[david_martin]

attempts to warm tyre up by extra downforce involves so much extra downforce ( it works by flexing tyre carcass more..not friction, car effectively slides less ) as to be on the bad side of max/min curve.

While deformation heating from internal friction in the carcass is the predominate mechanism in that example, dismissing friction is not necessarily correct. Even in high pressure, low slip cases the contribution of friction heat can still be significant. The friction power developed between the tyre and the road (and which is largely dissipated as heat) is the product of the frictional traction over the tyre surface and the the magnitude of the slipping velocity. So while increasing downforce reduces slip, it most often increases the frictional traction as well. Depending on the relative magnitude of the changes in the slip and traction, the friction heat can be relatively constant over a large window of contact conditions.

[RDV]

While deformation heating from internal friction in the carcass is the predominate mechanism in that example, dismissing friction is not necessarily correct

.

we do not dismiss friction, one of the time honoured solutions to get temperature when tyre compound notch is wrong for ambient temps (more importantly track temps. ) is to run much more toe-in or out ( which increase scrubbing ,hence tyre temp, but as only affecting surface is not as efficient as increasing camber ( which flexes carcass more) down side is as soon as tyre "cogs " ang starts rising in temperature , you are at wrong camber angle for best use, is mainly a qualifying "band-aid " to get some grip

Even in high pressure, low slip cases the contribution of friction heat can still be significant. The friction power developed between the tyre and the road (and which is largely dissipated as heat) is the product of the frictional traction over the tyre surface and the the magnitude of the slipping velocity

.

tyre temperature is generated by a combination of carcass deflection and the relative slip between start of contact patch (looking at contact patch as a chord of tyre circumference, it is obligatorily a straight line) as angular speed stays constant , tangencial speed goes down as rolling radius diminishes by forcing tyre surface to run on plane rather than circle (hope I am being clear enough on this..) this speeding up and slowing down of the rubber surface causes the relative slip between tyre and asphalt that generates grip and also warms it up . so I agree in that sense , this is the major cause of compound warming except if running tyre at disastrously low pressures
notice the slip is between start of a given point contact and middle of contact patch, it then returns to almost same on exiting surface due to the trailing edge standing wave

So while increasing downforce reduces slip, it most often increases the frictional traction as well. Depending on the relative magnitude of the changes in the slip and traction, the friction heat can be relatively constant over a large window of contact conditions.

yes , see above

[MarkWill]

Excellent information to date. If I understand the explainations correctly though, it would imply that on a bumpy or twisty track, tyres get warmer (more flexing of the carcass) and stay "grippier". It also implies that on longer straights the fronts get cooler (although I doubt that a second or two difference is enough to cool them too much below optimum). San Marino is quite a short, bumpy track, so I would have thought that there would not be a heat problem, but as mentioned before, some cars couldn't get their tyres to work up to optimum temp, so I wonder what the cause of this would be?


By the way, RDV, could you explain the "cogging tyres ang starts rising in temperature" statement - are you saying that as tyres start cogging if the camber angle is too high, and this overheats them? (I also want to point out that I agree about the oil, so I suggested a hot air blower instead, to raise the ambient temperature on the part of the tyre not in contact with the track).

[RDV]

Mark, re "cogging" meant positive feedback effect, if tyres are sliding due to low grip surface or too hard compound for conditions , they do not heat up, but if you can get over the "hump" and start generating some grip, that in turn heats it up, which makes the compound come in more , which heats the tyre more, in a "virtuous circle".. each tyre carcass/compound combination will have a different point at which they start working. Some tracks are quite particular, independently of compounds taken for example at A1 ring cars have to run several laps before tyre comes in , check out next qualifying there...

[MarkWill]

Thanks for the clarification. So why did some cars fail to get the tyres up to temp?

[AAH]

Last year some pictures appeared of tire temp sensors on the McLarens in testing that used 5 or 6 infared sensors hung off the rear wing and front chassis; some said they were just merely safety bumbers, but I've heard otherwise. Regardeless, I'm curious as to if people have seen tire temp profiles from similar tests. I've been told that I would be surprised by the results, but never has anyone shared them with me.

Me, I have to think that for road course setups, the poor man's tire temp probe is going to be sufficient and maybe better because it can measure the tire temp below the surface. Now, granted, there are instances like the USGP front straight/oval where the tire temp has time to increase dramatically, but I would think that an average tire temp measured in the pit (or stopped on the track in a test session) would be a really good indication of what is happening on the track from corner to corner. I don't know, is the data really beneficial or is it a case of "we have the ability to generate another 20 channels worth of data, so why not?"

Another ? kind of in the same tire testing arena; has anyone ever heard of teams using a 6 DOF force-moment wheel commonly used in automotive testing. Seems to me, that this device, if adapted to an f1 wheel, would be the best measuring device for tire testing. There is a 1 DOF lateral force measing tool (GEM device) which has been use in CART for quite some time.

Aaron

[RDV]

tire temp profiles from similar tests. I've been told that I would be surprised by the results

will post some pix and graphs to desmo so he can then post them in this thread ...

yes you would be surprised , it will need a paradigm shift, remember when discussing tyre temps we always talk about pitlane temperatures, these are very subject to drivers pace on in lap and shape (radius & lenght )of last corner and straight. so remember track temps are going to be up to 60% higher than pit lane temps, and distribuition can be quite different

sensor information gives temp profile inner-mid-outer and change thro` corner , this gives information on when compound is in optimal temp range , effects of geometry and settings, and so on...

common sense and experience can make temperatures reading give much information , specially if "eyeballing tyre surface at same time, colour of rubber and graining pattern very informative, fingernail "shore durometer" test completes picture.

True temps are scanned by infrared sensors , these are easily installed in gt`s and LMP`s but quite intrusive on single seaters, also catering for steering on front wheels make that side quite difficult, problem can be solved by rotating mirror scanner or having six to ten element array to cover tyre through swing, rear tyre OK with three sensors.

Accurate tyre temp profiles for tyres depend on outer temps but also inner air temperature ( which control pressures) and hence carcass stiffness , this data is collected using radio linked pressure and temperature sensors inside tyre. pressure variation due to variation of air volume inside tyre can be quite considerable.

Mark.... So why did some cars fail to get the tyres up to temp?

downforce , geometry and driving style conspire to keep it from "cogging" and ramping up into proper operating temperature for compound. Also teams chose different compound depending on pit-stop strategy, and you might get caught on wrong side of the equation.
Agressive geometry ( which makes carcasses work more) can get you the temperature, but down side , will deteriorate tyre more on long run , a case of good for qualifying , bad for race, getting the good compromise is the holy grail, surprisingly driver style is a great part of this....

(GEM device) which has been use in CART for quite some time.

it was introduced by Don Halliday, but I seem to remember it as a 3DOF measurer
, effectively strain gauging wishbones allows you to derive contact patch loads , if you can accurately remove hysteresis effects

[RDV]

could you explain the "cogging tyres ang starts

I see the question , maybe you see ang as "angle " , actually mistyped and

[MarkWill]

The fog is clearing.....thanks. I understand the "warm the tyres up enough to get them working, then they'll take care of themselves" bit. Now a development of the theory - as the tyres wear down and get thinner, they must become more efficient at losing heat, right (I assume that the rubber is a poor conductor of heat, so the thinner the tyre tread, the more heat should be lost to the environment)? But assuming that the track stays at the same temperature, and the contact patch is the same area, doesn't this imply that the tyre will now get cooler because the track is a giant heat sink- i.e. the older the tyre, the cooler it gets? Is this a contribution, beyond plain old wearing of the tread as to why older tyres have less grip, or am I trying to be too smart?

[desmo]

"example is on car into 200kph corner running on very cold day , new tyres unheated."



http://members.atlas...ireTempData.art
http://members.atlas...pDataLegend.art



Pardon my French (in the legend for the graph- it's self explanatory, except perhaps for vitesse=speed!)

[MarkWill]

Thanks RDV/desmo


This graph explains a lot. I can see that after half a kilometer the tyres started to warm themselves, and you can clearly see that the fronts are cooler than the rears (By the way, what type of IR sensor is used here - I'm looking for one for a different application, but which involves high levels of vibration for a short perod of time)? So the first 500m is the run-up to the corner, followed by about a 450m drive around the bend, followed by another straight (which is why the temp drops of as speed increases out of the corner)?

Its interesting to see that up to the middle of the tyre the temps are pretty close, but the exterior front is way down (which is where you would need my air blower to be pointing for it to be any use. Hmm I can see why it wouldn't do much good, unless you duct hot air through the nose and out through the front wing - not really feasible with the way the wings are suspended off the nose. Another idea bites the dust).

[RDV]

at the cost of quoting another thread , from yelnats very elegantly worded description in "Tyres grip and all that..." thread=

It is during cornering that the length of the contact patch has a greatest influence on heat generation.

For a tire to generate cornering forces it must rotate at an angle to it's direction of travel (misleadingly called 'slip' angle) introducing an element of 'squirm' in the tread at the contact patch that is proportional to the contact patch length, 'slip' angle and lateral force. It is this squirming and the resulting hysterisis friction that heats a tire much more than it's deflection to load, assuming we are talking about a high speed road or racing operation. In a contact patch under heavy cornering, the trailing edge begin to lose traction before the middle portion reaches its limit, the longer the contact patch the greater the effect of this phenomenom and the slower reacting is the tire to the turning angle. So a wider tire will feel more responsive to the driver, an important factor on both road and track with the added benifit of requiring less contact pressure (inflation pressure) per unit of contact patch length. The reduced pressure has the add benifit reducing the shear forces per unit of contact patch to improve the co-efficent of friction and allowing the use of softer compounds to further improve the situation! A win - win situation all around!

[lumepo03]

The operating temperature of todays F1 tyres is 149 C/ 300 f at the carcass. Tread temperature is very difficult to measure as the surface
of the tyre acts as a huge radiator. The tyres' pressure is is one of the areas that seems to cause some confusion. The tyres' pressure is set to carry a certain weight. Now the problem is at a F1 car traveling at 60 mph
has a different aerodynamic load (vehicle weight) then the same car traveling at 150 mph. The tyres have to be brought up to temperature so that all the molecules can become friendly with each other. This is akin to having a little conversation before heading into the bedroom. I have been experimenting with variable pressure systems for some time now and I am very suprised that none of the teams have looked into this. All F1 teams use either Nitrogen tyre inflation or medical air to inflate their tyres.
In the case of N2 (nitrogen) it would not be too difficult to outfit a car
with a N2 harvester and controller. My experience with Michelin is that they will eventually get it right but like most French, prefers to be closesingle minded about it. I am French so I know of what I speak. Many a time I have crossed swords with Michelin and even as recently as a few weeks ago recieved an apology from them concerning a matter with Air Liquide. I welcome a telephone call from Patrick Head, Frank Williams or even Michelin. Nudge Nudge, know what I mean, know what I mean!!!!!!!!!

Look closely at the Ferrari and their N2 Supplier.

ACME brick

[MarkWill]

lumepo03, I would have thought that you would not need absolute tread temperature values - you can get by with relative values, surely? What I mean by this is that if you have a temperature sensor in a particular place on the car, and it reads an apparent tyre temperature, then all you need to know subsequently is that the measured temperature is higher or lower in relation to the first one? Thats what the setup shown by RDV looked like it was doing, because the temperature profile around the tyre must vary not only across the tyre but also around the circumference as well (I'm guessing that the foreward facing part of the tyre is cooler than the trailing part of the tyre.

Can you explain what the principal of a variable pressure system is?

[lumepo03]

I thought I gave you a clue when I said that the load carrying capacity of
the tyre is dictated by 2 things; Tyre pressure and the construction of the tyre. There is a given spring rate within the tyre at a certain psi.
Change the psi value and the spring rate changes. Now the problem is almost cyclic. The tyre must be able to withstand a certain weight/load. This means that the tyre psi must not fall below this value or you will essentially have a under inflated tyre and get more carcass/sidewall flex
giving you higher temperatures in the sidewall. This could lead to delamination (Ford Explorer). This also means that the spring rate of the car is softer leading to chassis rub. All the teams try to find a happy medium in which to work. A variable pressure system would do away with many of these problems and would tailor load carrying capacity to what it needs to be at a particular point on the circuit. This would also allow for eltronically controlled suspension systems. I am very curious about the brake system on the Ferrari. I came up with a device similar to that one
although only in the conceptual stage. I was trying to address the tyre warming issues. I am certain that one of the functions the system serves is controlling tyre temperatures. Anyway I came up with an even better one then that. Just waiting to see when the rest of the teams catch on to it.

ACME brick

Time to go to my meeting, Will check back in 8 hours.

[MarkWill]

Thanks for the details. Its not obvious to me that you can get a good correlation betwen internal tyre pressure and external tyre temperature, but if you say that it works, I'll accept that you've done more research into it than I have.

One of the bigger potential practical issues I would see with a reactive pressure system would be when it comes to changing the tyres - how do you ensure that the gas feed is reliably reconnected (I'm sure it can be worked out). Also, depressurizing the tyres if required looks like a challenge, although I think the key there may be in pressure BALANCE (still, you're losing heated up gas, and when new gas gets fed into the system, it too would need to be heated). Its an interesting approach thats got me thinking.

[MarkWill]

Hi,

Well, a small group of people (engineers - I had design, thermal, and a project leader from one of our Space Station projects - impressive stuff) got together to discuss this at lunchtime, and we've got it licked!!! You're right, the system can become an electronically controlled suspension system, and it could be Ferrari's "ace in the hole". Certainly, the system looks promising - and quite easy to implement. I'm not sure if it wouldn't be considered as "breaking the rules" though - it depends on your definition of "suspension". Anyway, the principle looks sound, given the small number of parameters we looked at. Probably if this was a real project we'd discover that there are a ton of things that come into the equation that we ignored, but for a lunchtime discussion, it was pretty decent. Well done lumepo03 - good fuel for thought.

[RDV]

As far as controling pressure and changing spring rates, there are proprietary systems on the market which are used on offroad racing cars. Excelent for getting out of sand and for varying track conditions, off road cars go from asphalt to hard earth to fine sand to soft sand at speeds from 5kph to 250kph.

It used to be a bone of contention that on the Paris Dakar T1 & T2 not alowed to use it and T3 yes , now on proto class it is allowed .

As far as maintaining correct ( or desired ) tyre pressures , all teams use a simple spread sheet derived from Boyle`s law to set initial pressure at a given temperature , be it in or out of thermal blankets, and you can chose wether to "come in " in 1 st, 2nd or Nth lap , depending if a qualifying session or race.

Conversely any deviation from expected "mission profile" can wrong foot you on pressure and even ride heigth ;I`ve always assumed that part of the problem at Imola in 94 was running behind pace car , which allowed tyres to cool , which lowered pressures , which allowed car to bottom.

Usually drivers comments that second set of tyres was better or worse than first is because pre-set pressures were not right on first or second ( or Nth) set , due to wrong estimation of ambient,track or tyre temperature evolution.

IE pressure rise related to temperature will change spring rate of tyre considerably, typicaly on current tyre 1 psi up/down equivalent to 50 lbs/in on tyre spring rate .

A quick setup change can be done just by dropping or raising tyre pressures.

As to systems for auto-correcting pressures to a fixed value , has been used in endurance racing and Indy-cars, and banned , at least by the FIA as valves too prone to blow off under kerb-strikes or centrifugation. LeMans saw several cases of cars dropping on rims due to the last effect.

Tyre manufacturers not too keen on idea despite obvious advantages due to unreliability of systems so far, under racing conditions.

As to Mark`s comments on suitable system for pressure controlers and practicability , interstate 18 wheelers already use the system to monitor and maintain their tyres pressures , and very reliably, under continuous and hard operating circumstances.

Ferrari have indeed on board ( or rather in-wheel ) tyre temperature and pressure sensors, which transmit data to the dashboard, same transmitters enable tyre sets to be monitored while in the blankets in pits.

Have used these sensors also in other formulae , and the FIA always approved their use ( on safety grounds) even on formulae that did not allow telemetry ( sending a radio signal from car component to car was not considered telemetry ) as long as not connected to an active system that would change the pressure.

Yet another case of nothing new under the sun...

[RDV]

Also

Marc.....temperature profile around the tyre must vary not only across the tyre but also around the circumference as well (I'm guessing that the foreward facing part of the tyre is cooler than the trailing part of the tyre

.


, yes ,having ascertained that by sample measuring in preliminary work , is the the reason sensors are mounted as close as we can get to tread leaving ground IE to the rear of car and as low as possible, this avoids cooling effect of airstream and the fact that rear tyres are typicaly " slipstreaming the fronts" and therefore cooled less.

[MarkWill]

Hi RDV,

Thats interesting - because it implies that you assume that the "true" tyre temp is what you read in the "dead air" region (I'm assuming that thats what it is)behind the tyres, or rather, you base your relative performance on temperatures measured in this region? How quickly does this air respond to changes in the tyre temps - and does it ebb and flow with changes in speed?

[RDV]

"true" tyre temp is what you read in the "dead air" region

not exactly, there are two (well more actually..) reasons for temp monitoring, one is to ascertain suspension use of tyre , and temps coming of trailing edge of contact patch are the ones that will give the highest temperatures , and consequently the biggest deltas across contact patch, when fine tuning geometry and dynamics (bars , springs cambers etc..) will show up better.

The pressure control for spring rate reasons relates more to in-tyre air temperature, this also shows big deltas to surface temps, most illuminating to watch air temp vs. press vs contact patch temps as car goes down straight , brakes and turns, pressure in tyre depends not only on temperature but also on Fz , and quite difficult to separate in normal use, would need many sensors and very high frequency of aqquisition , also that piece of equipment money cannot buy = time to analyse

have started some research projects in the past on this , but although very interesting never finished due to lack of time.

and also (well ,I did say more than two....) you can see when tyre is in its working envelope, normally not a critical factor as working in middle of range, but sometimes weather conditions, dyrty tracks or supplyer mistake in tyre range brings this to the fore.

and yes temp does go up and down with speed , see graph I posted thro` desmo

[Jezztor]

Am I the only one that can't see those graphs? Haven't been able to see them since they were put up. Probably a stupid question but is there a special viewer I need to be able to process a .art file? That is the only thing i can think of that would cause the notorious red [X]

Jezz

[MarkWill]

Hi RDV,

Yes, I looked at the graphs, and I see they they change in temperature, but my question was more aimed at response time - once more thinking about the "reactive" suspension part if it - and the veracity of the temperature data (I'm trying to think of ways you could map out the true tyre temperature, although I'm sure that what is currently picked up is good enough for the teams).

[desmo]

Jezz, The ART images read fine in my old IE5 browser. I tried seeing if they could be read as GIFs in IE5 but it didn't work. What browser are you using?

[Jezztor]

IE 5 too...I've tried to open the graphs on all 3 PC's i have here at home on the network - neither displays them...must be some funky little setting that isn't activated ... but I don't understand what - despite having taken computer studies at school!



Jezz

[desmo]

Graph


Legend

Jezz perhaps you could right click on these links, choose "Save Target As" and import them into any image software you might have and view them in that program. I think most any freeware or shareware image software should read ART images.

[Jezztor]

I tried that upon premier epreuve , to my disgust it did not work...what program seems to cater for the format that you're using, desmo? I've tried numerous, the constant error message being "invalid file format"...


Jezz

[desmo]

That does appear to be a pretty obscure file format. My Paint Studio doesn't recognize it, and my Netscape 4.7 browser gives the following text instead of showing the image:    

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:lol: :cry: Maybe you need an old French computer to see it!

[MarkWill]

Hi,

I've sent a message to jezztor and desmo - I can e-mail them a .bmp copy of the tyre files if they want to drop me a line.


Ref. RDV - seperating the Fz component, - are you referring to the Fz component in the tyre wall, on the hub, or where?


Info on cornering force vs. temp would be interesting - once you get over the "hump" I wonder what the gain is in cornering ability as temperature rises? If you can get the temperature delta between the inner tyre wall and the outer tyre wall down to a minimum, what difference can that make?

[MarkWill]

Another quick question - probably there are people out there with the answers - the temperature sensors work because of emmissivity from the tyre surface. Does this emmissivity number change depending on the tyre compound?

[lumepo03]

MarkWill , if I understand your question correctly then the answer is
yes. Although these sensors are very impressive they do leave out some very interesting and important variables. Besides the sensor set-up is only giving information of the tyres' surface. I suspect that Michelin and Bridgestone have sensors or chips mounted in the tyre to record the information more accurately. The surface sensors show how the temperature moves across the tyre from bead to bead but does not show pressure variation. This is actually of more interest to the tyre engineer. Tyre computer chips that record information have a very negative side to them. Since the Ford Explorer story, tyre manufacturers' have been looking into installing these chips as a way of defending themselves. This will no doubt opent the way for law enforcement to get into the act. Imagine the days of RaDaR as being over and Police now being able to read the tyres heat signal and know whether the tyre is underinflated, issue a citation for that and download information from the tyre and also issue a speeding violation.
I seemed to have gotten off the subject. Pardon me.

Peter

[MarkWill]

Hi,

A tyre looks like a fairly difficult thing to reliably instrument, although I'm sure that by now the Michelin and Bridgestione guys have it down to an art. Getting back to the "getting heat into tyres" thing, do the suppliers vary the cross section of the tyre across the width of the tyreÉ

[desmo]

I've heard rumors that temp sensors have indeed been imbedded in the tires' carcasses to get telemetry there. Can't say if it's true though.

[Froilan_G]

RDV,

a few questions for you. Somewhere in this thread you were talking about increasing camber to use the carcass to warm-up, but this would be only for a few laps, because after the tyre is heated, you'd be running too much camber.

What is too much camber? What are the parameters you look at? Is it temperature distribution? Or is it information from the tyre manufacturer that dictates the amount of camber used?

Talking about temperature ditributions, f I look at desmo's graph, I see the Inner en Middle temperatures being similar, but the Outside is quite a deal lower. Is this ideal?
Also, I was once present during a French F3 test, where Michelin was also taking tyre temperatures. I saw that the between Inner and Middle, there was a 13 degrees C difference, Inner being the highest, and same for Middle and Outside. I asked about this, and they responded that it was 'No problem, it is okay'. So is this part of experience, I mean, the Michelin guys know that when they have such a temperature difference over the tyre surface in the pits, the on-track temperatures will be good? Or is it just that for optimal tyre use, the temperature does not need to be evenly spread across the surface?

[RDV]

...aarghh just wrote a huge screed on all of froilans and marks questions and lost it due to wrong key stroke , will try to reproduce tomorrow, as 23h allready and race this weekend so a bit short on time...

[lumepo03]

MarkWill

In a perfect world no. Teams will sometimes reject tyres because the
tolerances are not ideal. By this I mean that the dimensions of the front
tyres may be off slightly. Now do not presume that it is only the fronts it could also be the rears. Anyway the process of tyre making is still a manual affair when it comes to laying up the tyre. When a green tyre is put into the mold the is a certain percentage of tolerance that is deemed acceptable (a green tyre is a tyre before the molding process). Now the crosssection of that tyre should fall within those tolerances. When the tyre is mounted it is usually kept inflated for at least 24 hours so that
the belt package is stretched correctly. After the circumference of the tyre is measured from one bead side to the other it is recorded and the tyre is deemed acceptable or not. Now the cross section of the tyre is
different from left side to right side. One area that certainly helps the build heat into the tyre is the materials used in the contstruction of the tyre. I am not referring to the compounds in use but the actual materials used in making the carcass. Some materials have different temperature operating windows and of course different strengths. This could be having an effect on the drop off in perfromance of the MIchelin tyres. I wonder whether Michelin is preparing to release a tyre that is capable of matching performance of the Bridgestone but in a one stop strategy?

ACME brick

[lumepo03]

MarkWill

I accidentlly posted without finishing. I was saying that perhaps Michelin is preparing to debut a tyre that could go for 1 stop or for no stops.
I imagine a tyre that has a memory. I have already mentioned to you about load carrying capacity. Well I wonder if they are developing a tyre that knows when the actual weight of the vehicle is getting lighter, as in fuel load and thus we see a performance change in the tyre keeping it competitive. I suppose this could be called an active tyre. Keep in mind the tyre would know weight judged by acceleration and braking but not by downforce. Why develop this while they race? perhaps to fine tune the system while keeping costs down and DATA accumulation up. Just a thought.
Incidently this would give them an advantage in building in heat. The Space Shuttle program is a good reference this technology. The Concorde seems to have benefitted from the NASA program.

ACME brick

[MarkWill]

Hi lumepo03 et al,

Could you clue me in on the Shuttle Program reference? From what I know about the Shuttle, it isn't the best instrumented piece of equipment on the planet. I don't know many of the Shuttle designers (we work mainly on the payloads and the robot arm), but if there's something specific I might be able to find a person... Are you saying that the Shuttle has "smart" tyres?

[RDV]

The Concorde seems to have benefitted from the NASA program.

...er... the Concorde is a 40 year old design , wouldnt really call it cutting edge, no matter what the french think....

[lumepo03]

MarkWill

I am looking through some paperwork to find a article on the Concorde tyres. I think that most of us know that the Concorde is a 40 year old design. RDF it may be wise to first read, then process information before letting your funny remarks fly off your fingertips. We are discussing tyres
on the Concorde. You are probably aware that they are not the original tyres from the 1960s. They have been recently upgraded with Michelin Radials.

I always though that the forum was a way of communicating not showing the rest of us how juvenile some of you can behave.

Anyway as I was saying, the article in question spoke about the cross section of the tyre and how the belt package changed with heat. I know that a certain amount of growth is expected as the tyre expands and contracts, but what piqued my interest was the apparent way that it perfprmed this task.

MarkWill are you located in the Clearlake area of Texas or in Irvine California. Just curious as I am familar with both areas.


ACME brick