“ are rfactor2 physics broken” video

Discussion in 'General Discussion' started by GTClub_wajdi, Dec 29, 2020.

  1. Nieubermesch

    Nieubermesch Registered

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    It's definitely true. You check for yourself. Almost every simulation/game (DR2 for example) doesn't quite translate the fidelity of physics on replays
     
  2. Nieubermesch

    Nieubermesch Registered

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    That might have been me, and I am not totally proud of it. Still, it seems I had my reasons for suspicions, with this drifting behavior and maybe over the top throttle steering. Altough, Rfactor 2 setups normally come with quite low differential lock and at the time I didn't even processed how much that affects things like that.
     
  3. Nieubermesch

    Nieubermesch Registered

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    Now that's some exciting developments. Make Rfactor 2 even greater again.
     
  4. Nieubermesch

    Nieubermesch Registered

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    Depends on the reasoning behind less sliding. It could be that tyres are more snappy and sliding is not a advisable way to drive them with exploits. At least that's what I hope, as temperature obviously play a big role over the snappy nature of a slide, as the more it slides the more the rubber will give away it's grip. Right now it seems like at some angles, the accelaration of a slide doesn't change, and that's one of the reasons you can slide and mantain all front speed.
     
  5. Lazza

    Lazza Registered

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    Done any modding?

    (note I'm referring to the second sentence - of course rF2 doesn't do CFD, no game can)
     
    Last edited: Jan 6, 2021
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  6. Nieubermesch

    Nieubermesch Registered

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    Care to elaborate on any of that?
     
  7. Slip_Angel

    Slip_Angel Registered

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    Yea this is what i'm hoping for as well. By sliding if they mean both understeer and oversteer will be punished much severely then it is a good change.
     
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  8. Lazza

    Lazza Registered

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    Aero squares with speed, so from a quick calculation which I hope isn't wrong, the speed started 6.7% higher and therefore drag should be 14% higher, but is 25% higher. I'm not immediately convinced Stefan judged that slope by eye and knew the rate was off, as there seems to be a focus on rake which would have a much smaller effect in comparison, but at first glance this does appear to be off.

    The post in question does appear (without any further explanation) to be centered on the downforce, and the front does produce a lot more downforce there. Unless I'm forgetting something, that should be purely aerodynamic downforce - nothing to do with load or weight transfer with braking G force. There are a number of aero params that could influence that, mainly front wing and diffuser related.
     
  9. Comante

    Comante Registered

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    You don't need any fluid simulation , you can simply measure height, velocity, angle and having some auxiliary parameters you can calculate a resulting value. It is approximate? Sure. It can work well enough for us.
     
  10. Yzangard

    Yzangard Registered

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    To reply someone that stated that perfect grip should be somewhere between rFactor 2 and iRacing, I've made some testing (with ACC and AMS 2 as well) and the results are that grip is better in iRacing than in rFactor 2, which is on par with other sims (iRacing top lateral forces where 2.6 G with Audi R8 LMS while others where somewhere between 2.3 and 2.4). All considered, grip is pretty much the same with all simulations.

    All tests where consolidated by telemetry with Motec so I'm 100% sure of the results (they were not just my opinion), even with slight differences in track condition / weather, results are still pertinent enough.

    Where things start to evolve a lot is when the car is sliding...here, things are VERY different. Tyre temps went up to 300°C in rFactor 2 (and AMS 2 / ACC) but temp are lowering pretty fast (almost as fast as the climbed actually, a bit slower) while iRacing's temps only went up to 150° (HALF OF IT !!!!) and lowered slower...problem seems to be in the track surface, in iRacing it seems there is no friction so you don't get back grip quickly enough while in rFactor 2 (and ACC) you can get grip back much faster, you still lose time but you don't lose the car as easily (but still in a realistic way imho). AMS 2 is lost somewhere in between.

    Issue doesn't seem to be with grip per say but with sliding and grip recovery.


    EDIT : my bad, I was aiming for the Audi R8 LMS but since it doesn't exist in AMS 2, I felt back to AMG (which i don't like but "for the science" I did it).
     
    Last edited: Jan 6, 2021
  11. Yzangard

    Yzangard Registered

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    Not sure I read it correctly but with the "no arb" version you are leaving the turn at 190 Km /h while with ARB P4 you are at 200 Km/h, seems to be a big difference and explains grip difference.

    That being said, the more you stiff arb, the less the car rolls so the more the car is reactive and "easier" to place...but you don't gain grip, at all, even the opposite. Losing ARB is making the car roll a bit more so gain mechanical grip, it will just be less reactive and imprecise.

    Note as well that we don't know if the camber is correctly set for ARB P4 so we have no clue what should happen if you lower the ARB stiffness...your point might be valid on this but you might be completely wrong as well.
     
  12. Comante

    Comante Registered

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    We know that in RF2 the temperature measurement is the outermost layer of the tire surface, the same measurement you could achieve with a IR sensor looking at the tire. I don't know how Iracing work, so maybe, the measured temperature is deeper in the tire section, or maybe is simply completely different in the modeling of the simulated tire, but the behaviour you describe seem coherent with core temperature (lower peak temperature, slower variation).
     
  13. Yzangard

    Yzangard Registered

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    Well, the whole lap got similar temps in all sims, temps were climbing and lowering at the exact same pace and exact same place until I willingly hit the brakes (I always disable ABS when practicing, old habit) abruptly to force a huge slide (each time I hit the brakes when I was at 240 km/h). I doubt it is core temp or why was it climbing and lowering like every other sim ?
     
    Last edited: Jan 6, 2021
  14. Yzangard

    Yzangard Registered

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    You are both correct and wrong imho. you are correct when you say the behaviour mainly occurs in straight line and high speed but it also happens in high speed corners, because there is a limit beyond which the spring won't compress anymore (bump stop, packers, dunno what you are using, they are here to limit compression). In High speed corners (but REALLY high speed ones, not mid speed ones) outer springs are so compressed that they can't go any further and inner ones are compressed as well due to aero (but not as much, I agree with you, of course). This tends to mitigate the relatively softer springs in those corners.

    Now, keep in mind we are talking about VERY high speed corners...

    On a side note @Slip_Angel, I agree that we should be allowed to discuss flaws and problems in our simulations but we should also moderate our words a bit, sometimes it's more like a schoolyard where the goal is to humiliate the other as much as possible. I'm not writing this especially for you, it's more general...


    EDIT : noticed later that @Comante replied exactly the same thing, my bad.
     
    Last edited: Jan 6, 2021
  15. Yzangard

    Yzangard Registered

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    Indeed, as a dev you obviously know the meaning of "realtime application" :)
     
  16. Yzangard

    Yzangard Registered

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    I think he meant "rFactor Pro" but might be wrong.
     
  17. Yzangard

    Yzangard Registered

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    Actually "real time" in development means that something outside of the main loop can IMMEDIATELY interrupt the main loop. We are talking about real time in industry for example, imagine an assembly line with a man who would get his arm stuck, if the machine was not able to stop immediately, this man could lose his arm. These automatons have a real time OS that allows them to stop any operation instantly no matter what happens.


    What he is explaining is that drivers inputs aren't interrupting the main loop, they are part of the main loop.

    Windows isn't a real time OS anyway...not built that way.
     
    Last edited: Jan 6, 2021
  18. Yzangard

    Yzangard Registered

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    We're talking about rFactor 2, not X-Plane 11, we're not in a giant wind tunnel either :)
     
  19. Slip_Angel

    Slip_Angel Registered

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    Nope speed is the same, check it out again.
     
  20. Yzangard

    Yzangard Registered

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    Yep, was on lower resolution and it was actually 198, not 190.
     

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