“ are rfactor2 physics broken” video

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

  1. mantasisg

    mantasisg Registered

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    Nope, something still not alligning about this. In my mind the dry surface grip levels should not affect the grip balance of a car, I think grip should change proportionally, unless there would be some exact differences in tires rubber compounds and treads. In wet the balance definitely can change because wider tires has more challenge to remove water, as much as I know.

    Thats interesting. I never heard about, so it is weird if its widely known. I might have missed it. Perhaps by a chance there are any additional real life references to this phenomenon ?

    Could it also be down to perception ? Oversteer is usually much stronger sensation than understeer, true ? So when grip increases reduced oversteer feels more than proportionally reduced understeer ?

    Driving style perhaps could be a factor too. So if driver has a tendency to overuse throttle at mid-to-exit before straightening out the car, but never use too much steering input. So in such case driver is always underperforming his front slip angles, and always overperforming rear slip ratios. In such case it makes sense that with increase of grip more improvement would be perceived at rear than at front.
     
  2. Sim_Player

    Sim_Player Registered

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    @mantasisg i feel same too, grip should increase proportionally.(if everything on car is same).
    I think on low grip level car is easier to get in rotation compared to high grip level. This may be why the phenomenon.
    The higher grip surface allows us to extract underlying rear end grip potential, hence it will feel like rear end is more stable at higher grip surface.
     
  3. Lazza

    Lazza Registered

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    You don't need to simulate all that to produce correct handling, if you have good enough data or spend enough time testing and adjusting.

    You're blindly defending rF2 without understanding the discussion you're replying to.

    Watch basically any real life race weekend that starts on a green track.
     
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  4. davidporeilly

    davidporeilly Registered

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    @cristianuk
    This is not how grown up people discuss things ( by hurling insults).
    We all need to be able to attack a position without attacking the person.
    Over 1000 disparate views here and yours is the first that does this.
    Bad choice.
     
  5. cristianuk

    cristianuk Registered

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    forget about my insults and explain how Ermin was wrong to call rf2 phisics broken by testing a set up just on one car, "are rf2 phisics broken" are poping everywere i mean really everywere even when you start Rf2 it pops in peoples faces , this guy is just misleding
     
  6. Lazza

    Lazza Registered

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    Here's my review of the video (back on page 4): https://forum.studio-397.com/index....ysics-broken”-video.68348/page-4#post-1052911
     
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  7. Remco Majoor

    Remco Majoor Registered

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    Are you 12? You can't just insult someone and then just say, ignore that. You're disrespectful and not participating in the discussion at all. I reported you (before you are thinking lazza or someone else did that) good luck on the future
     
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  8. cristianuk

    cristianuk Registered

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  9. mantasisg

    mantasisg Registered

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    I expected you could offer better reference than that. I don't have time to study multiple hours of racing just to check a little doubt. Not only that, I don't think that reliable observations could be made this way. What should I do ? Watch and estimate how many times and how hard cetain car understeer and oversteer, and then make a graph ? Would it even really answer anything, since any good driver is a major influence if car gets pushed more to oversteer or understeer ?

    I hoped you could offer some more precise reference, as you said that phenomenon is "widely known". To check this more reliably one should try it himself IRL, and do it without confirmation bias, and to avoid any placebo. Also helpful would be to find literal evidence by drivers or engineers.

    For now, I'll stand by my thinking that mechanical grip balance should remain the same at any dry surface grip levels.

    The only mechanical reason I could think of is that higher friction would aid to more body roll, higher centripetal accelerations. So I suppose whichever end experiences more load sensitivity (higher load switch magnitude), could have more impact due to higher cornering forces.
     
    Last edited: Feb 22, 2021
  10. davidporeilly

    davidporeilly Registered

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    I have observed many times in different levels of motorsport this known phenomenon. One that comes to mind is Jensen Button discussing how that in early test session upon arrival at a new circuit that the team is constantly looking to solve oversteer but as the sessions progress the balance just comes back to them.
    To help your understanding I even did some google searches and was surprised to see so few references but there were several in karting forums advising to "loosen up" the setup if the track is well rubbered.

    I have experienced it IRL as a driver first hand when a test day on Friday yields some oversteer but by Sunday the car is neutral.
    Rockingham was low grip and green, all teams needed to change car balance from higher grip track settings.

    One very convincing item is that when F1 teams pit to change from a soft tyre to a harder tyre they reduce front wing to match the rear grip. (the harder tyre being a good surrogate for a less grippy surface). Total grip is reduced and the rear suffers more therefore the front grip has to be lowered.
    In sim racing we do this also.

    Last night in an FSR test race my first soft tyre stint produced even tyre wear, my second stint with same tyre , same fuel load the front tyres slid and wore more (I will screen shot the motec graph). This was due to increased track grip impacting the cars balance.

    None of these examples involve the variables that you mention such as differing driver styles.

    If you remain unconvinced I suggest you set up a test session at say Nazareth oval. Set realroad at green and progression to a to a multiple. Start the session with a good car balance on the green track and drive. Keep putting on fresh tyres. You will find the car becomes more understeery as the grip improves.

    Beyond that I cant make it my career to convince you of this phenomena.
     
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  11. davidporeilly

    davidporeilly Registered

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    Talk to the hand.
     
  12. Lazza

    Lazza Registered

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    Pretty much any race weekend in that scenario is filled with 2 practice sessions full of people saying "Have to be careful about chasing car setup here, because car balance will change with track evolution." Possibly in every racing series I've ever watched. Including bikes.
     
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  13. Remco Majoor

    Remco Majoor Registered

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    Yea, see me insulting anyone there?
     
  14. mantasisg

    mantasisg Registered

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    Thanks guys, I will pay attention to that stuff from now on.
     
  15. Lazza

    Lazza Registered

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    @mantasisg I get the analytical thinking, it's a good thing. But sometimes you just start with facts and go from there; most people don't look at the motion of the planets, fail to come up with calculations that predict them, and decide the planets aren't really moving the way they appear. (apparently some do that; luckily scientists gave it a good few goes and eventually got it pretty much right)

    As David alluded to, this isn't the sort of thing you really find in reference material. But it's talked about a lot, including in simracing, because it's just a thing that happens. Hence I say it's widely known. Not trying to be flippant or smartarse, it just 'is'.

    To relate that to the thread somewhat, for the same reason I'd be cautious about judging physics based on setup changes that "should do this, but do that." The good setup guides I've read use words like generally when describing the effect of setup changes. Too many variables to just come up with rock solid answers.
     
  16. Comante

    Comante Registered

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    Without ever considering that in complex systems, every changes has secondary effects, and in some circumstances those "secondary" effect may have a significant magnitude. This is true for the most simple basics of driving (braking/accelerating/turning) to the most advanced setup options, where often it is said that a change on a axis has actually effect on the opposed axis.
     
  17. mantasisg

    mantasisg Registered

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    I choose talking about those many variables instead. Otherwise it is not interesting, and not very meaningful. It is a shame that it is also too difficult, too time consuming and not as easy to use as already digested truths. IMO it is much more fun to understand some prinicples that will be universally true, than have to memorize lots of truths that "genrally" fits in limited settings. There are things that comes close as rock solid answers, but those are like small details that comes in combinations when we have to define how some particular system works. Too nerdy... not widely consumable.
     
  18. Sim_Player

    Sim_Player Registered

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    @mantasisg This might help with what lazza and david are trying to say.
    Look at 16:55 only >


    track rubbering up means higher grip level. Also note that he says "hard and fast " rule not 100% accurate. basically a rule of thumb.
     
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  19. mantasisg

    mantasisg Registered

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    Wow, thanks, thats 1000% spot on. What an epic channel, definitely subscribing.

    Indeed what this engineer said agrees to what Lazza and David are saying. So it must be a lot of truth in it. I like that this engineer shows the awareness of this not being a hard rule, but it sounds like it is mostly true for F1.

    It wasn't explained why it happens, appart than "it depends on tires". It would be interesting to get deeper into how that works.

    We could accept that it "just is a fact, and it is just somethign that happens", but that would be too easy, and nothing would be learned from that :D

    Further in the video the engineers mention ride comfort, and that there is very little suspension travel at front comparing to rear. I think it could be one bit of the reason for this phenomenon. Just assuming that with rubbered track cornering forces are higher and inevitably there is more roll, the front end could run out of travel comparing to the rear, resulting in the shift of grip balance. Anyway... thats just one idea, I suppose there could be lots of different reasons, and combinations of those reasons. It is just an interesting thing to think about.
     
  20. Sim_Player

    Sim_Player Registered

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    @mantasisg I think the increase of grip is largely dependent on drive type i.e fwd or rwd or awd.
    In rwd you will feel most grip increase in rear when surface grip level increases.
    because rwd car is heavily limited during exit phase of cornering (where you are putting down power just after the apex but steering wheel is still not fully straight.)
    A simple example would be, if on a green surface you can put 20% throttle without oversteer at a given point AFTER apex then when the surface will grip UP then you can put 30% throttle without oversteer AT THE SAME point.

    Similarly for FWD this will cause reduced understeer at exit where front are worked hard. (as again at exit phase of cornering you are asking both longitude and lateral grip BUT mostly longitudnal)

    So basically this phenomenon will be MOST dependent on drive train type and mostly beneficial at exit phase of cornering.
    Rwd will feel less oversteery at exit phase of cornering and fwd will feel less understeery at exit phase of corner.
     
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