Physics and tire models of racing sims

Discussion in 'General Discussion' started by Korva7, Apr 4, 2015.

  1. Korva7

    Korva7 Registered

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    I thought it would be interesting to have a thread about physics engines and tire models of various racing sims. If you have some information or thoughts about these things, you can post them here, or if you know good web pages about this, you can post them too.
    I have been playing rFactor 2, game stock car extreme and assetto corsa recently, so i am especially interested about differences between those, but discussion about any sims would be appreciated.

    Also information about how things are done for different sims would be nice. For examble that is test drivers who have driven the real thing used for getting feedback?
     
  2. Rich Goodwin

    Rich Goodwin Registered

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  3. Emery

    Emery Registered

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    Niels wrote a very good paper in 2012 about the trials of using Pacejka curves: http://isiforums.net/f/showthread.php/3710-PDF-tires-in-race-simulations-some-thoughts.

    I think the rF2 tire model is an attempt to predictably work around the problems Niels cites. Right now the rF2 tire model has a minor problem with the contact patch not matching real world data, such that air pressure & camber adjustments don't quite bring about the right effect.
     
  4. Korva7

    Korva7 Registered

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    Thanks. That paper was very interesting. As Niels works for Reiza Studios i think game stock car extreme's tyre model is parallel to niels view. Meaning tyre maker is in direct control of the forces that tires generate in different situations, and tires properties are mostly based on tyre makers subjective view and knowledge. And real data is not trusted because it usually is not accurate.
     
    Last edited by a moderator: Apr 4, 2015
  5. DurgeDriven

    DurgeDriven Banned

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    This is sorts of things need dissecting by experts in cross sim reviews. :cool:

    Not just saying " the car felt believable and responded like I would think " .......as if that is enough feedback on physics chassis and tyres, one sentence out of 2 pages.

    How about the comparative feel and performance of a under inflated , hot or worn tyre in the 3 sims mentioned above, let alone 50 other things.
     
  6. Emery

    Emery Registered

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    It's not so much that it isn't accurate, rather, like anything you measure, you want to do it with the same instruments and the same operator so repeatability is improved. For tires, there just aren't enough measurements available for us average folks to draw conclusions useful for simracing.

    Think of horsepower measured on dynamometers... no two dynamometers will give you the same readings and no two runs will give you the same readings. The skilled operator can make sure the variance is a lot less than an unskilled operator. And a skilled operator can interpret the torque curves better than an unskilled operator. For tires, Niels is a skilled operator :) Pity that the old racesimcentral database went belly up because Niels wrote a lot on there!

    What's useful about the rF2 tire model is that you know changing the construction will predictably change the tire. This means modders aren't trying to interpret the outer ranges of the Pacejka curve. And because the tire is flexible, we now get that "feel" coming back through the steering wheel.
     
  7. Andregee

    Andregee Registered

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    Rf2 and AC are the only sims that allows flatspoting, but in Ac they are not physically correct and simulatet. It is only a canned effect in the FFB because you can slip 1 mile sideways and no flatspots will be generated and if they are generated after break locking you can´t notice any chassis der suspension vibration.
    The graining and blistering effect in AC are such simply generated effects too and not irreversible what they are in real life, so i don´t miss it in rFactor2
     
  8. Guimengo

    Guimengo Guest

    AC's FFB is emulating the steering sensation so you don't feel the car as you do in rFactor2. From all I have read it also seems to have a much nicer FFB sweet spot for wheels G27 and less.
     
  9. Andregee

    Andregee Registered

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    Kunos said that the ffb is native generated by the suspension geometry and it feels so that i think its true what say said. You can feel bumps, stronger forces with higher corner speed and so on like you feel it in rFactor2 and its not compareable with the old emulated FFB System of rfactor1 and all Simbin games with the canned effects. And i can tell you the feeling with a G27 is poor in Ac, because the wheel is not powerfull enough to generate a dynamic range of effects. Its the same story like in rFactor2 where a G27 is a weak toy.
     
  10. msportdan

    msportdan Banned

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    [MENTION][/MENTION]

    So is gsc realfeel canned effects?

    So why in gsc when ur stationary and turn the wheel, its tight as a real car. But in rf2 its all loose as thought theres no rubber causing friction
     
  11. Jamie Shorting

    Jamie Shorting Registered

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    Do you even play rF2? If you do I suggest you test this. Max front camber in garage settings and try. Then return to garage and put front camber to it's lowest settings and repeat test. Return to this thread and give results. If you don't feel the difference you have messed up your ffb beyond repair OR you don't use any.


    Anyway, sorry for going off topic. Misinformation around here annoys me. It's something I should work on I suppose.
     
  12. P.S.R.

    P.S.R. Registered

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    Just curious does anyone remember the old flatspotting Kuh-thunk Kuh-thunk you would get I mean this was a long time ago but just wondered why only the high frequency now?
     
  13. Minibull

    Minibull Member

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    I feel it in low speed corners still, when turning the wheel and loading up the tyres, but now there is also a high speed vibration in a straight line, which is like they are reproducing the crazy bad vibes youd get at high speeds with a flatspot. The ones where the f1 drivers would say they could barely see.
     
  14. Andregee

    Andregee Registered

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    Realfeel is an external made plugin and not the ISI Gmotor 2.0 Standart and it does not work in all Simbin titles.
     
  15. P.S.R.

    P.S.R. Registered

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    Yeah I forgot to say "slow" almost like tire was...well...flat...as in out of air but anyway I remember the first time I felt it and was impressed but the next build took it out or so I thought...
     
  16. Lazza

    Lazza Registered

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    Was all tyre wear accelerated early on? Been too long... can't remember...
     
  17. P.S.R.

    P.S.R. Registered

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    Don't think so just real road I think.
     
  18. Acoutsa

    Acoutsa Registered

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    Hi !! I play AC for its FFB level on the steering wheel that I find great !! I learned about flying in rfactor FFB in 2008 and with time I tried with leo's FFB then with RealFeel tuners which are both great, but I found it was less than RealFeel compliquerl !! I had some notion of cars behavioral bases of different traction and power thanks to them !! Hey Now I completely forgot Rfactor for Rfactor 2 is even more better about everything, compared Rfactor !! But now Rfactor between 2 and AC at FFB on the steering wheel, I prefer AC !!

    And you think about how physics Rf2 and AC? Turning cons are different in both simulator !! At the drifts are they feasible as in AC? Physical levels between these two different simulators, which are the most realistic !!:confused:
     
  19. matf1

    matf1 Registered

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    If you are not happy with the FFB, change it until you are :)

    Rfactor 2 is far more realistic. AC is using 'tricks' to give you that feeling.

    Sent from my Nexus 4 using Tapatalk
     
  20. msportdan

    msportdan Banned

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    the more I play rf2 the more I realise what most of you ar on about. ive been hotswapping between gsc and rf2 for the last 5 hours... I can tell the differences in the improved tyre temp and wear, the fact that in gsc 2 corners later and the tyres are up top temp. the realroad which bring a track to you in a race. the ai in gsc which are very aggressive and bump you a lot, even on lower level ai. the ffb, which I can now tell how it makes rf2 better if it is more subtle. the fr35 is a blast so is the clio and well the brabham lets say I need more practice with that lol

    now with rf2 gfx update, it looks great. I just need to get rid of the jaggies on the white lines then im done. for gsc I used a patched clamp dll, not sure the 64bit version of the patch works in rf2. see more previous thread.

    cheers
     

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