Latest Physics Blog Update: New off-road tyre features.

how about the Resistance of surface in the TDF , it is still not working ! !
ice have no resistance when you drive on it but RoadTrack surface and all other surface normally had
so tire dont burn anymore on grass or gravel , ok it's much better but , you can still cross througt a gravel trap without been slow
and a last thing , the Sparks of collision still miss mostly on rails and on the track surface (very convenient to know when the chassis of cars is too low on a track )
i cannot understand why F1 players or other openwheels players dont ask it ? ?

 

Tire temperature is a consequence of heating and cooling. Tire slide is the biggest responsible for heating and ground conductance for cooling.


Part of the generated heat will go to the tire but not 100%. The increase in temperature for the asphalt is for sure much smaller than for tires due to its bigger mass but that doesn't mean that the heat going to asphalt is negligible at all. Simply consider that when no sliding occurs it is the main cooling agent.

In order to calculate that actual heat input due to sliding, only the part going to the tire should be used.

Saying that for offroad is 6% and for asphalt is 100% but that it can be tuned seems a wild guess to me. Where do this figures coming from?

Asphalt is sensibly cooler than the tire but has 60% diffusivity compared to tire tread so I would expect a similar amount sliding heat to be dissipated through it and through the tire.

For what I have searched these heat partition coefficients are quite costly to calculate since they usually require both empirical and simulation data.

 

We really don't. It would be up to the mod maker to supply an air pressure range that is both long lasting when properly inflated, AND penalizing when either under or over inflated. You might search out pirelli for F1 or Continental/Michelin for IMSA to see if they have press releases related to tire failures. I never said it would be easy to accomplish this...but I would think this newer tire model should be able to implement such features to control everyone just running the absolute minimum tire pressures.

 

Speaking of official content, it would be nice if S397 provided some guideline for their cars.
I really liked being able to read the Radical manual, it's fun to compare real data with the sim.

 

I think it's also possible that by 100% they mean 100% of the heating power coming to the direction of the tyre and the heating power going to the road is taken into account before that. But there is no reason to think that based on how the text was written.
Would be nice to hear a comment about this from someone at s397

 

Hey, Dave..
Pirellis and Michelins tires work both with the minimum pressure of 18 and 17 psi for the Porsche Cup with targets of 27 and 29 psi... For the GT3 here the minimum pressure is 20psi, so is quite correct what they put for us... The tire should not been penalised... What you should to ask is different track temp... Because in rf2 is still locked in 29ºC and with this value, the lower pressure setup on the car will hit this target without more wear if you not overdrive.. the advantage of use more pressure on the tire is is when you have a lower track temp track condition to hit the ideal "hot pressure"

 

Sorry but the text is clear and your statement makes no sense since it doesn't comply energy conservation principle. Generated heat goes to the tire or to the track. There is no further splitting.

The provided values make absolutely no sense.Why a wet road would provide a 1:1 relation between tire to track heat fluxes and a dry track would absorb no heat at all, going all the heat to the tire?

They have been adjusted very poorly IMO, probably knowing that doing it properly would require revisiting all created content to comply with proper thermal model.

If you think that when a tire slides doesn't heat a dry track you should look at this video.

 

I guess it was to make it compatible with old temperature data for a dry track, without any other "study" about energy. They want to include the old data in a new model that comprehends off track adventures, which does not include the actual heat transfer. I'm just guessing, does it make sense?

 

Well, probably 99% of the yellow matter that shine on the tarmac is just molten rubber, and anyway probably the heat on the ground is just very very very superficial, and this is an extreme example, just like saying that a burning car on the track should turn the grass yellow and then ignite it.. I think I can survive without this feature.

 

Has any content been updated with these improvements?

 

The problem is that that heat is affecting the tire while it shouldn't. The track not being heat up is not the key part.

Tire temps are being incorrectly calculated. That's what you need to survive with.

 

No.

 

I know they are unrealistic because in real life gt3s they run tire pressures at about 180kpa. It's quickest in rf2 to run them at minimum which is 140kpa. I also know it's unrealistic because it allows you to use very sharp inputs to gain time instead of being smooth with the steering.

This is me winning this race against some very good competition so I know what I'm talking about when I talk about how to get the most out of this tire model in terms of laptime. I based my race setup entirely around keeping the tire pressures as low as possible because that's the biggest factor that slows you down over the race distance in this car. Not tire degradation. Doesn't seem too realistic.

It's true that the Pirelli F1 runs best at the minimum allowed pressures. But this is just one tire. It's not the case across the history of motorsport. The minimum allowed rear tire pressure in f1 is about 135kpa. Here again we can look at what rf2 would have you believe. The Formula ISI 2012 allows you to run the rear tire pressure at 100kpa and that's what's quickest. That's standard atmospheric pressure! Am I seriously to believe f1 cars would go quickest if they left the garage with flat tires?

In real life you don't just go with the minimum allowed tire pressures. You look at the tire temps across the tire to make sure that you're using the most of the tire possible. This is just irrelavant in rf2 and that's not realistic.

I'm passionate about this because guys come to rf2 because they hear about this super advanced tire model and then they spend an hour making a setup and realise that the devs screwed up massively on the tire pressure. It's a pity because it would be the ultimate driving sim if they could just sort it out.

 

This is half the point. There is no ideal hot pressure in rf2, just whatever the lowest pressure you can run.

 

Are you talking about relative or absolute pressure? What does rFactor 2 show in the garage?

 

That's the point. After a few laps I got nearly 170-180 kpa with quickest laptimes. Ok I can't say that the first laps are slower caused by
the temperature or the low pressure but it's even impossible to say that 140kpa are good for the fastest lap because the pressure increases with the temperature and does not linger at 140kpa

 

If rFactor 2 shows relative pressure, it would mean that the tire absolute pressure is '100kpa + ambient pressure', which is about double atmospheric pressure, so not a completely flat tire. A tire is flat when relative pressure is 0kpa.

 

140 kpa is initial cold pressure, it's the minimum allowed, which means that probably everyone should use this pressure, if you look on motec, you will see that after some laps the pressure will stabilize around 180 kpa hot on most of the tracks.

For your knowledge, the minimum allowed in iRacing GT3 cars is 138 kpa.

 

Usually the manometers, show relative presure. If a manometer indicates 0, usually is ≅1 bar (atmospheric presure).
Then 100 kpa, really are ≅ 200 kpa

 

What If I told you that for example Blancpain afaik has limited cold pressures to 155 Kpa but teams run some tricks to start with much lower pressures than that? You seem too attached to some mystical numbers for pressures etc but in reality same cars on different tyre brands could go best just below 200 kpa and on another around 170.

Cool story.

What if I told you that Pirelli mandates minimum pressures to avoid risk of tyre failures? Not for performance reasons. There were times when for example Schumacher was famous for taking pressures as low as 100-115 cold pressures for the start. Resulting with his tyres dancing on their rims behind SC when the tyres cooled down enough.

Actually you do. If it gives you best results then you go with it. Simple as that.

No they haven't. Quite the contrary. They got it really close to reality, the only thing missing is weather changes being hooked to physics. So when we get overcast it actually cools down the track and therefore affecting tyres.