“ are rfactor2 physics broken” video

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

  1. Yzangard

    Yzangard Registered

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    I am considering the highest possible lateral G Force without too much understeer, it is quite hard to define, it is more a range than a precise value. If you take the highest value shown by the curve (which is an approximation actually), it shows a slip angle a bit above 9° but here you have a lot of understeer (I disabled oversteer color range for readability) :

    upload_2021-1-22_12-52-0.png

    I think the ideal value a bit lower, where dots are in the 0 to 4° slip angle color range but as you can see, it is not a very clear value, it is more a range.

    I know this is just an approximation and it misses some important data but we can still see that even with high slip angle, we still manage to get important grip, maybe too much.

    I will try to unlock locked channels but dunno how to do it. Yet.

    PS : there are channels dealing with suspension forces, maybe I could extrapolate something from them, they are not locked.
     
    Last edited: Jan 22, 2021
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  2. Slip_Angel

    Slip_Angel Registered

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    Good find mate. I hope S397 look into this quickly.
     
  3. Yzangard

    Yzangard Registered

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    It is only one car, over 2 laps, under certain conditions and the data are not complete, so the analysis may not be correct, it just gives an idea. The curves are very similar to what you get when you test the tires in the lab, so I think the physics is not bad, it may just be a setup. Also the car is a GTE, so with more Down Force than a GT3, it must also have an impact, I would have to redo the tests with other cars and more laps.

    It may indeed be too permissive but according to these curves and those obtained by the scientists, we are still very close, just a slight shift of ideal Slip Angle.

    To get to the heart of it, I would have to find a way to test the behavior with the blocked channels but I don't know how to unblock them, I know it's feasible because a BoP analysis has been published by a user just unblocking the GTE channels.
     
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  4. Nieubermesch

    Nieubermesch Registered

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  5. Kevin van Dooren

    Kevin van Dooren Member

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    So what you call the ideal value is based on the curvefit.
    Like you already said its an approximation, it doesnt come close the the raw data behavior at higher slip angles.
    Raw data is always leading, curvefitting is just a tool. In this case that ideal value does not make any sense.
     
  6. Yzangard

    Yzangard Registered

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    No, not the curve as I said, I am watching points and their color. I pointed the top curve point to show you that actual best grip point was shifting to the left.

    That being said it is all I have, it is not perfect but still gives an idea, I don't know how to filter values so I could only keep those when the car won't slip at all.

    Also keep in mind that the only G Force channel available is the one for the car, not the ones on each wheel, which of course modifies the results.
     
    Last edited: Jan 22, 2021
  7. Stefan_L_01

    Stefan_L_01 Registered

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    Race tire or street tire? Big difference!
    You dont want your race tire to slide all time a lot to get max grip. And it would cause too much drag. Street tires are designed to be forgiving
     
  8. Nieubermesch

    Nieubermesch Registered

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    I wonder if anyone finds this handling familiar, and it comes from a quite hated sim on the market. I had already made a remark about how PC2 has an issue of inicial understeer and then it will grip as you apply more steering angle... I've seen around that Madness engine is build upon ISI motor engine. Reading the theories of Spinelli it came to mind to go and watch PC2 understeer behavior. Might give it a go (PC2) and see how that resembles Rfactor2 handling at all, minus probable other physics quirks, trying to isolate understeer and grip dynamics.
     
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  9. Havner

    Havner Registered

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    Heh, it indeed looks like rF2 in terms of overturning the wheel when entering the corner when driving GT3/GTE.
    I know the wheel is not visible, but it can be seen nonetheless from the cabin view how the car rotates.
     
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  10. Comante

    Comante Registered

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    This is called wishful thinking. I see unicorn farts in this video.
     
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  11. Nieubermesch

    Nieubermesch Registered

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    It looks even more porposterous in this video, that sort of behavior.

    I don't mean to say anything with that video, just letting people come to their own thoughts and if it can be helpful for the discussion, since Stepahn comment about what could be happening brought me back to this theories I had already seem floating around.

    Well, I just left it here to see what people think. I see some resemblance, but also see some resemblance of that in ACC... Although PC2 is "worse" and I've heard many times how you have to throw the car into corners there, and that does remind me of the alien exploits people are talking about with Rfactor2, where cars and thrown into the corners, understeer apparently exploited. Let's see after some further investigation what more people like Stephan and such say about the grip dynamics.
     
  12. mantasisg

    mantasisg Registered

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    That Audi at Imola was 8s off pace from WR, or I did not understand something.

    The thing that looks really weird in that PC2 video is how sudden is initial turn in. Very strong. Also car is bouncing like a jelly. And I never felt PC2 natural, grip in there was never predictable to me, like if some extra effect outside reasonable physics would be helping to deal with handling at over the limit, and then the same effect at some times would make it harder instead of making it all chill and easy... Depite Project Cars originas, I don't feel much in common, just as with RaceRoom for example. Too much stuff altered very much. Only Automobilista seemed to carry on the qualities of rFactor.

    No comments on Laguna Seca PC2 video... thats just PC2 in a nutshell in there.

    Here is real onboard, with similar car. Lots more stable, nice, smooth, but also noticeable sharpness and demand on driver to stay focused and get the angles right as quickly as possible to cary that speed.
     
  13. Nieubermesch

    Nieubermesch Registered

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    It wasn't about lap times, I didn't even take any notice of that, just the driving in itself.

    Well, we can say that Rfactor2 seems to have cars that under certain circunstances also make the sliding forviging, and I just had the idea of merging some things I've seen before and what Stepah said in a post with one or two possible theories he has, where the car seems to have grip and able to rotate when it should start to either understeer or oversteer. Although I really I am not trying to put Rfactor2 on the same patamar as PC2, as I said the phsyics problems there go beyond just what can be seen on the video.

    What I think can be helpful, is if it really is some core issue even beyond the tires and it can resemble a bit of PC2, than it could be something to investigate, I don't know.

    In that video, although setup and other things can be at play, Rfactor2 doesn't seem to have the same edginess in the same type of cars and I think you also have agrreed to that somewhat, right?
     
  14. Comante

    Comante Registered

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    I feel we are drifting away from the ground to fly in a fantasy real detached from reality. The only "reference" must be real example, and the only "opinion" must come in the form of telemetry and graphs and data.
     
  15. Nieubermesch

    Nieubermesch Registered

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    Well, some tests have been made by Stephan and he already showed he knows how to work with telemetry and such... What he has theorized just converge with some of the things I remembered being said about ISI physics. Not saying postulating anything about it, just raising awareness if it could be pertinent for the discussion. I don't understand why some people will jump to the neck of some sims just by driving and watching them but then the other it has to be totally proven brfore any statement can be made...
     
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  16. Andregee

    Andregee Registered

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    The madness engine had an inertia bug which Reiza fixed for AMS2. Thats the reason why the carss in Cars1+2 seem turn react so suddenly
     
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  17. Nieubermesch

    Nieubermesch Registered

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    I wonder how much that could still be at play in Rfactor2 iteration of the engine... it could have been made better but some of it still being left of, I don't know.
     
  18. Yzangard

    Yzangard Registered

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    Yep, will do more testings with correct data soon and post results since previous ones were only estimations...
     
    Last edited: Jan 23, 2021
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  19. Yzangard

    Yzangard Registered

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    If I remember correctly (which isn't obvious since I've read a lot of tests), all the tires have more or less the same behaviour, the race tires just have a higher peak grip with a slightly steeper drop just after the optimum grip but then the loss of grip is much lighter, so the curve goes down slowly afterwards.
     
  20. Andregee

    Andregee Registered

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    It was a problem in Gmotor engine based games like GT Legends, Automobilista till Reiza fixed it and as a part of the old code base in the madness engine like i told but it was never a problem in rFactor2
     

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