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Thread: A quasi-objective way to judge physics of sim cars

  1. #1

    A quasi-objective way to judge physics of sim cars

    How realistic are Sim cars? This is an interesting question most people like to ask. There are tones of discussion on this subject online. Most of them turned out to be helpless. This question will live on as long as Sim products live. To answer this question, of course, objective studies need to be done by comparing to real cars and on real tracks in:
    • Grip state; and
    • Non-grip state (sliding state).

    1) Grip state: a car dynamic behavior in a grip state has been extensively studied. The physics of a car in grip state is pretty known defined, and most models applied in simulations are very successful in the past years. Two online published results on rF1 with modified F3 cars showed
    rFactor indeed are very accurate, could be up to ~95% in accuracy. I could take this for grant that latest sims such rF2, AC, iRacing maybe even better. So we may not need to address grip state on this subject.2)

    2) Non-grip state (sliding state): dynamic behavior is not that well studied and when and how a car starts to slide is pretty much “unknown”, as “black art”: So, judging if a sim is realistic or not is mainly based on comparing on real life on non-grip state (driving at and beyond the limit) sees more meaningful.

    Of course, we have no data be compared for non-grip state. I came a quasi-objective way to do this, by referencing Chris Harri techniques one real sliding.
    Chris Harris has been sliding many of cars on his videos. He taught us how exactly he did step-by-step. Here is his video shown how to step-by-step slide a BMW M235i:



    AC has the same BMW car. For rF2, one can expect to slide Nissan Z370 in the same way. One shall note that you have to turn off all assistance OFF as he did on real cars and with NO tuning (setup) --- shall use factory default!

    Assetto Corsa has wide range of selections road cars. The following cars in Assetto Corsa were found in Chris Harris videos (he slide all in exactly same way he taught us):

    Ferrari La Ferrari:
    https://www.youtube.com/watch?v=GaAQW8lVaRM

    Ferrari F40:
    https://www.youtube.com/watch?v=3MDTcXGsjuo

    McLaren MP4-12C
    https://www.youtube.com/watch?v=5mKB-8WUB5k

    Mercedes SLS AMG
    https://www.youtube.com/watch?v=UkjqQ1rXpRs


    Please do not reply “I can slide those cars”, this is not an answer! If both AC and rF2 implement physics on sliding state is correct, then one shall be able to slide those sim cars just as he did a way on real cars.--- applying max throttle on rear tires with reversed max slip angle of front tires. If you can do it, please provide video to prove if you can. Then I believe the physics is correct. (please no tuning -- setup. use Factory default).

  2. #2
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    I'm scared.

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    Do...do we award points? Or give really intense and excited Japanese commentary? XD

  4. #4
    read the post carefully and watch the videos first if your IQ is high enough.

    your first video is not the way Chris Harris sliding. the slip angle is wrong direction!
    rest videos you posted are not worth...

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    I don't understand, for which cars do you want a comparison ?

  6. #6
    Quote Originally Posted by boblevieux View Post
    I don't understand, for which cars do you want a comparison ?
    the listed cars Chris Harris did are all listed in AC. For rF2, you can try any rear-wheel-drive car. If rF2 physics correct, one shall be able to do so, because he did consistently on all real cars.

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    Quote Originally Posted by Joe View Post
    the listed cars Chris Harris did are all listed in AC. For rF2, you can try any rear-wheel-drive car. If rF2 physics correct, one shall be able to do so, because he did consistently on all real cars.
    Except Chris Harris is on street tires rather than race tires, so the technique may not have similar timing. And I'm not sure if the 370Z in rF2 has street spring/shock rates available. Drifting consistently is not so easy as it looks for the unpracticed, as Randy Pobst showed in a video a couple months ago.

    Edit: there's a great rF2 video of someone (gui?) drifting out of Sao Paulo pit lane with the Cobra.

    Edit: Paul Loatman!

  8. #8
    DurgeDriven
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    Please do not reply “I can slide those cars”, this is not an answer!

    Okay, whatever you say.....

    This is an interesting question most people like to ask.

    Funny, never asked it in my lifetime

    I KNOW what I feel, I KNOW what I like.


    Stop worrying or giving credence what others perceive and have fun !@!

  9. #9
    Quote Originally Posted by Emery View Post
    Except Chris Harris is on street tires rather than race tires, so the technique may not have similar timing. And I'm not sure if the 370Z in rF2 has street spring/shock rates available. Drifting consistently is not so easy as it looks for the unpracticed, as Randy Pobst showed in a video a couple months ago.

    Edit: there's a great rF2 video of someone (gui?) drifting out of Sao Paulo pit lane with the Cobra.
    The Chris Harris teaching on his BMW video is showing how to get into a sliding state, which is a deterministic state. In other words, it is can be applied to others as long as you master his techniques. He did just like that for all other cars.

    See at 6:1, 6:30, 10:27, 11:56, 12:50, 13:30, 13:50, and 14:15 in his Ferrari La Ferrari video:
    https://www.youtube.com/watch?v=GaAQW8lVaRM

    see at 0:40, 5:13, 8:30, 8:47, 9:04, and 9:20 in his Mercedes SLS AMG video:
    https://www.youtube.com/watch?v=UkjqQ1rXpRs

    This is only "quasi-objective" way I can think of, using his techniques to slide the sim cars. Without this reference, then we turn out to be subjective again.

    there are only two outcomes here:
    1) you just cannot master his techniques;
    2) if so, but you still could not slide the car as he did, then physics is not correct. Otherwise, it is correct.

  10. #10
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    Quote Originally Posted by Emery View Post
    Except Chris Harris is on street tires rather than race tires, so the technique may not have similar timing. And I'm not sure if the 370Z in rF2 has street spring/shock rates available. Drifting consistently is not so easy as it looks for the unpracticed, as Randy Pobst showed in a video a couple months ago.

    Edit: there's a great rF2 video of someone (gui?) drifting out of Sao Paulo pit lane with the Cobra.

    Edit: Paul Loatman!
    The underlying physics in that video were a bit different to what they are now, it was before some suspension fixes in one of the builds which made the cars feel a bit better, a bit more dynamic, and probably a bit more stable in a slide. So if it was possible to do it before that change, it should easily be possible now with the current build. Also, part of what i was managing when i did that video was the FFB itself, i was using the default FFB on the "high" mode on the AF which doesn't point the wheel in the direction that the car is traveling in an accurate way and there was a lower speed limit on the AF back then. With my current JSON settings and using the responsive mode, it's much easier since the wheel points in the direction of the slide in a more realistic way so i can rely much more on the steering.

    I know the NSX, Panoz, and Corvettes can all be drifted. The Panoz is very easy to drift, the power-to-weight makes it very predictable. The NSX requires a bit more coaxing to get it into a slide, but once you're in it it's easy to control since it doesn't have a huge amount of power. The Corvette depends on the exact model, but all have a lot of power so it's similar to the Cobra where you have to manage the throttle more than the other cars after initiating a slide.

    I think the Panoz is the easiest car to drift, so if anyone wants to try it in rF2, that would be a good car to start with. I don't think the Corvette is a good car to learn with because it's so easy to just put your foot down and get wheel spin, and the suspension is good enough that controlling it afterwards is very easy. The NSX or Panoz are probably better to learn with since you'll have to learn how to actually throw a car into a slide under braking or with inertia.
    Realistic FFB settings with Accuforce (responsive mode): Accuforce settings

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