rF2 FFB system and philosophy

Discussion in 'General Discussion' started by DrivingFast, Nov 4, 2020.

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  1. mantasisg

    mantasisg Registered

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    I suppose there shouldn't be an issue about holding vehicle up enough to avoid riding wheels rims. Probably even with particular amount of downforce added. My thinking is that very low pressures should have cost of cornering stiffness, and transients in general. Tire just simply should barely work without all that stiffness. And all that assuming its ok that tire stays on and doesn't get shredded because it is not simulated.
     
  2. avenger82

    avenger82 Registered

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    Are you seriously trying to defend this obvious bug, by saying that minimum allowed pressure in setup is still higher then flat tire pressure and is enough to lift cars’ weight?
     
  3. Comante

    Comante Registered

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    It's not an "obvious" bug, it's called math. The only thing to investigate is lateral carcass stiffness, that depending tire construction can or cannot be related to internal pressure (good luck in determining that). No simulator in the world simulate tire damages, so, this "bug" is present in any product on the market. Is a simulation limit, not a bug.
    To see if there is a bug in the pressure management of the simulation, you have to create a tire that allow a pressure of 0 , and demonstrate that a car with that tires is faster at 0 than with any other value.
     
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  4. avenger82

    avenger82 Registered

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    This bug is not even about tire damage due to low pressure. Problem is you’re always the fastest with lowest possible pressure in setup page. This is not realistic! Maybe in some cases and for short duration it’s sometimes true, but it’s not optimal choice for all track conditions and regardless of car setup etc. You’d get too high temperatures and tire wear for instance.
     
  5. Lazza

    Lazza Registered

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    You might find in rF2 you end up with worse grip on a long run because the wear is uneven. Note we can't see that.
     
  6. Comante

    Comante Registered

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    It is ALL about tire and rim damage.
     
  7. Andregee

    Andregee Registered

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    https://www.touringcartimes.com/201...e-minimum-tyre-pressure-level-safety-reasons/

    So it should be clear that using very low tyre pressure resulting in faster lap times without simulating tyre damage is far away from a bug
     
  8. Comante

    Comante Registered

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    If I remember correctly, after F1 Indianapolis 2005 GP, minimum tire pressures were increased by rule, because low pressure plus wrong tire selection from Michelin was considered one of the causes of blown tires.
     
  9. Comante

    Comante Registered

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    Grip is not the only factor you look for when making car setup, this is the reason to inflate tires over the "recommended minimum" but as always car setup is a balance of factors, low tire pressure increase grip, just like increased wing incidence increase load. Where and when you put them is your choice... but I cannot call it a bug if the outcome of an action is always the same and we have real world proof that this behaviour happen in the real world too.

    p.s. : there are real world car forums that talk about pressure and grip .... go take a look. :D
     
  10. avenger82

    avenger82 Registered

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    Guys stop defending lost cause. Even Marcel said in interview it’s not realistic and should be fixed.
     
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  11. Andregee

    Andregee Registered

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    Higher tyre pressures prevents the tyre from overheating on hotter track surfaces what actually could not happen in rf2, so there is no reason to not take the 1,4 bar what the GT cars offer
     
  12. pilAUTO

    pilAUTO Registered

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    rF2 is no longer the only game to offer a realistic experience. I think ACC can now be considered as realistic now, due to the lack of investment of S397 in physics.
     
  13. jepeto

    jepeto Registered

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    hello,
    with my drift oz , i have no ffb. I am looking for a wheel steering that reproduce the racing drive.
    i have not so lot of money but, i have found that the ts pc racer is well.
    What do you think about it ?

    Thanks for your quote
     
  14. Rui Santos

    Rui Santos Registered

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    Tire pressure, as well as compound to be used is allways related to ambient and track temperatures, if this is not the case here, there's a bug...

    Like @avenger82 said, even Marcel knows that this is not right and should be fixed "soon"

    Honestly, physics department improvement is what i want more for this sim, that would make rF2 a true challenge and a lot more immersive and tactical...
     
  15. Andregee

    Andregee Registered

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    Track temperature is allways calculated with 29 degrees so there is no reason for higher pressures to prevent overheating and thats not a bug
     
  16. avenger82

    avenger82 Registered

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    But you realize track temperature is not the only reason of overheating tires?
     
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  17. Comante

    Comante Registered

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    Off course heating is a side effect of friction, even internal friction so, more deformable is a tire due to low internal pressure , more it heat. Heat is wasted energy, so this energy is sucked from vehicle motion ( this mean more fuel burnt and or lower top speed). Airplanes lose a lot of landing energy exactly this way: tire deformation.
     
  18. Andregee

    Andregee Registered

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    1.4 bar minimum tyre pressure is an absolutely credible value for a track temperature of 29 degrees when less than 1 bar was used in real life under warmer conditiions. Due to the larger Contact Patch and the resulting higher grip you can even reduce the tyre temperature instead of producing more slip with higher pressure with less grip.
    One thing is fact, as it is simulated in ACC, that under a certain pressure of 27.5 psi you have less grip, it is complete nonsense, a member of a racing team reported this in Kunos Forum. Also in GT3 the teams try to drive as little as possible, but under the premise of avoiding punctures. The fact that in ACC the optimum tyre pressure Pirelli prescribes is the one with the best grip is wrong.In Formula 1 even the complete axles and brakes were heated up before the Fia checked the minimum tyre pressure in order to achieve the minimum pressure during the measurement, while afterwards you could start the race with less pressure because the larger contact patch offers advantages.
     
  19. Rui Santos

    Rui Santos Registered

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    Track temperature is allways calculated at 26ºC, not 29ºC!! Anyway do you think this is acceptable? This is clearly a bug! Track temperature depends on air temperature, if the sky is clear, if it's overcast, if it's night, etçª.

    This should be solved ASAP, because it's an aspect of this great simulation that puts it on par with some other "racing software", when it could be clearly on another level of simulation...
     
  20. doddynco

    doddynco Registered

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    I'm just jamming here but my thoughts are that lower pressures are faster due to a larger contact patch until one or more of these conditions listed below outweighs the contact patch benefit;

    • Increased hysteresis heats the compound beyond the optimum temperature (reduced coefficient of friction - in RF2)
    • Increased hysteresis heats the compound causing the rubber to degrade faster (faster degradation - in RF2)
    • Increased tyre flex causes handing/aerodynamic instability. (poor handling - in RF2)
    • Increased tyre flex and higher forces increases chance of seal leaking air. (damage - Not in RF2)
    • Contact patch 'pinches' the ground as it compresses. This can cause a very slight jacking up effect as the tyre compresses. This doesn't have a big impact and would likely be hugely outweighed by the larger contact patch (uneven load distribution, uneven and increased abrasion - in RF2)
    • Sidewalls bare too much load compared to the middle of the tyre (uneven load distribution, uneven abrasion - in RF2)
    • Slows the tyres transient response (takes longer to spring back into conformity with the road after bump) Unsure, however, some evidence suggests to me that transient response is not modeled in RF2 for any tyre nodes not in contact with the ground. i.e When a tyre node leaves the ground, it instantly reverts to its 'non-compressed' position within the tread. To put it another way, you can't simulate a memory foam matress in RF2. (Hope this makes sense) If this is true then it could be one of the biggest drawbacks of the tyre model.



    I'm sticking my neck out here and making an assumption but, the way ACC does 'optimum' tyre pressures is just a static curve for the coefficient of friction - it's neither realistic nor very complicated. The rubber compound doesn't become 'more grippy' just because there is more pressure in the ring of air it happens to be attached to.

    I'd really like to hear from one of the wizards who created the RF2 model, discussing its strengths, drawbacks and potential.

    My two cents is that RF2 tires are not perfect, but they are an insanely good attempt at trying to be.

    Edit:added a few points from Lazza
     
    Last edited: Nov 20, 2020

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