Poll: Is this driving realistic?

Discussion in 'General Discussion' started by Nieubermesch, Jan 23, 2021.

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Is this driving realistic?

  1. Yes

    31.6%
  2. No

    68.4%
  1. Yzangard

    Yzangard Registered

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    The question is whether my theory checks out and I'm pretty sure it won't, so in this case he's probably not blaming me for nothing...except that if we don't prove this point, it will remain an argument, a kind of easy to use sword of Damocles to criticize rFactor 2 again and again, so I prefer to check it once and for all.
     
  2. Havner

    Havner Registered

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    The biggest argument was given when aliens definitely showing their way of driving. The rest is an analysis. Your reasoning behind why this is possible might or might not be correct. But the issue is still there. Blaming you for anything means that the discussion should basically be dead. Because while discussing anyone can be wrong at any point.
     
  3. Yzangard

    Yzangard Registered

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    I might be wrong but I was under the impression that "detached" was misleading, that it was just the softest setting for ARB.
     
  4. Havner

    Havner Registered

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    I remember you saying that. But I don't remember whether you actually showed this in telemetry somehow. Anyway, lowering/detaching rear ARB by itself is not that powerful, so showing this to new people like the biggest exploit and then hearing they don't really need/like that is poor argument in my book.
     
  5. Yzangard

    Yzangard Registered

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    I never said that, I read it somewhere :)

    I never tested that, I don't have any clue how to test it actually :)
     
  6. Havner

    Havner Registered

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    Then someone else did. I remember this being mentioned in those threads :)

    Found it:
     
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  7. Slip_Angel

    Slip_Angel Registered

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    Ok this is important please read.
    What i observed is that the alien technique of overdriving is useful for certain corner types.
    for example corners that naturally makes car understeer, corners with tighter exit radius/line.
    what overdriving allows is getting through that understeer by adding more steering wheel.
    this comes at cost of tyre wear ONLY. and this is the key to the problem we talking about.

    lets see what setup exploits they use and what they should do realistically (in simplest terms)

    *low rear camber
    what is should do ?
    it should take away peak grip ,hence lower corner speed
    it should also make tyre wear unevenly due bad heat distribution

    *detached ARB (especially rear)
    what this should do ?

    more low speed understeer (which is present in RF2 BUT not to extent as it should be, as you can see the aliens can "force" through this behavior)

    more roll ,bad for aero

    more camber variation hence less grip etc

    **BTW i tested the effect of camber and ARB on skid pad. after consistent runs i see the "Expected results" i.e what i described above is happening in RF2. Problem is, despite these above factors are "working" why are they not used as they are intended ?**

    **i only checked camber and effect of arb on camber. NOT sure about how much effect of ARB is on aero.**
    some pictures of effect of arb on tyre temperature spread,hence camber
    IMG_9497.JPG IMG_9498.JPG IMG_9499.JPG IMG_9500.JPG

    Effects of rear camber
    IMG_9502.JPG IMG_9501.JPG IMG_9503.JPG

    On same conditions as i could possibly maintain.
    As you can see it is having "intended " effect but from my driving perspective the effects did not hinder me or put me in big disadvantage.

    My theory why low rear camber is used because cars in RF2 might be more punishing on braking, so lack of cornering ability is worth it.
    Low rear camber gives maximum patch during braking.
    Not to mention TC in RF2 is extremely bad, it is basically driving cheat code, i wonder how setup and driving will look in GT cars with TC and ABS OFF and on green track.

    *low wing

    what this should do ?

    in simplest term decrease the load on rear axel making it "light" hence more prone to oversteer

    does it happen in RF2 ?
    YES !
    but does it happen in realistic manner with good disadvantages ? NO !

    all this issues are pointing at car that is able to sustain such setup and driving style with good pace.

    I'm heavily confident that looking into tyres will solve the issues.

    my guess would be that this is due to
    1.lack of proper tyre damage model
    2. error in tyre relation to temp
    3. slip angles.
    4. from what i understand as @mantasisg said maybe on static vs sliding friction.

    The ability of understeer to push the cars straight needs to hit sooner and hit with big consequences

    The ability of oversteer to require opposite lock , spin out or tank slap should be more shorter time span.
    It takes much bigger mistake to get oversteer in RF2 in above mentioned 3 stages.
     
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  8. Comante

    Comante Registered

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    I disagree with most of your understanding of how setup work, but it's a waste of time to explain how and why. 80 pages distributed in 3 threads clearly show we can't contrast this cluttering, so better live with it.
     
  9. Yzangard

    Yzangard Registered

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    @Slip_Angel I disagree several of your understanding as well, but more importantly I fail to find a clear signification of "not punishing enough", I mean how exactly should the game punish you for excess driving ?

    With my setup and FFB strength, the game is punishing me A LOT if I drive like this, vibrations alone are just unbearable and force me to change tires, of course if I set smooth to something unrealistic with very low ffb, it is not a problem anymore but is it up to the simulation to fix this ?

    Can is by no mean easy to drive when doing this, not to mention I don't gain any time but once again, this is with my FFB level and my hardware (Simtag pedals, SC 2 are the main parts to know, Rexing 29 cm wheel is important to know as well).
     
  10. mantasisg

    mantasisg Registered

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    I have not noticed anything obviously wrong in Slip_angle's understandign of setup. All pretty basic stuff. Perhaps missed something, but looks alright to me. I would also add that running rather low pressures should require more camber, I think so because logically less pressurised tire will be less stiff, therefore will deform more. Very low pressures should also be a threat of causing fatigue stresses related tire failures, but of course... lets not get too far ahead.

    Just a point regardign the "detached" rear ARB. Even with reduced as much as it can be reduced antisway stiffness. The roll will still be suspended by springs and dampers too. So it must be considered. Also geometry should be considered too. Also... there is still overall roll stiffness that comes from front stiffness and also chassis stiffness.
     
  11. Yzangard

    Yzangard Registered

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    It is not the setup understanding but its consequences actually, the term "understanding" is a bit abusive, I just don't understand what consequences should happen that doesn't happen.

    Tire pressure that is too low should be more punitive, I agree with that, but again, how should that really translate? More heat due to higher deformation, so a tire that wears out faster but it seems to me that's what's happening, I just don't know how much it should penalize us. Besides I can't find any real study on how tires behave when the surface temperature is too high, all I could find was about the internal temperature that causes blistering but I don't think this is modeled in rF2. In any case, low tire pressures cause tire wear more easily and this is felt as vibrations quite noticeably.
     
  12. RaceNut

    RaceNut Registered

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    Extreme heating in tires can lead to delamination (self destruction will follow). Low air pressure + too extreme camber could be enough to cause severe problems pretty quickly. Delamination of a tire can cause other damage in various ways too, potentially damaging body parts (Aero) and more.
     
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  13. Yzangard

    Yzangard Registered

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    It is especially the tires of plane which undergo this kind of things, the temperatures are on average from 450 to 500°C at the landing and indeed, if one goes further this phenomenon can occur but for tires of car which do not exceed 150 to 200°C, I do not know if such a phenomenon can happen as easily (that said one already saw it in F1 it seems to me).

    In any case we don't have precise information on the temperatures at which this happens or even at what temperatures we lose grip, if we really lose grip from a certain temperature onwards...I really don't have that information.
     
  14. mantasisg

    mantasisg Registered

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    Yes, I also don't know a lot of that. Normally there are recommended tire pressure ranges for particular tires and particular cars, and I guess people just don't try to get freaky and don't experiment too much outside those ranges :D

    Speaking of very high heat, I was reading stuff yesterday. Was interested to find info that natural rubber softens and reverts. Synthetic rubber hardens and becomes brittle. Also some interesting stuff I read was that Michelin in the late 40s discovered that most significant portion of tire wear (but I suppose thats on more normal use, not racing) comes from heat generated in sidewalls from friction occuring between the plies, thats when they began developing radial tires.

    There is no doubt that rubber will go out of its operating range if it is too cold or too hot. I remember Aris back in AC days shared some operating ranges. And that information should be around, might try to search. High performance modern stuff as a rule will have narrow ranges. Classic bias ply tires will probably work well at 40C as well as at 80C. But the performance impact of tires at crazy temps might be difficult to find as they simply are never even imagined to work in those temperatures. And at really really crazy temps they would just splatter the rubber out due to centrifugal forces, and whole tire would break due to fatigue.
     
  15. Yzangard

    Yzangard Registered

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    From what I understood from the Michelin document on tires, the temperature alone does not indicate the behavior of the tire, it also talks about friction frequency, basically (and again if I understood correctly) the higher the friction frequency, the higher the ideal temperature, which could suggest that a tire during a slide (so with a high friction frequency) would not lose that much grip. Wear would be obvious, but the polymers that make up the tires have an extremely complex and well studied operation to avoid sudden loss of control.

    The internal temperature on the other hand is another story because if the temperature rises without a high frequency of friction, then the polymers become more "liquid" and adhere much less. Not to mention blistering and wear and tear which would become much higher of course, so this would not be a sustainable situation in the long term.

    In summary, sliding the tire on one lap would not have a huge impact on the performance of the tire, however it would clearly be very harmful on a longer term, which would finally make the "abusive" driving of the "aliens" that we were talking about much less unrealistic than it seems, from a tire point of view only.

    I still think it would not be feasible in a real car because of the forces involved and what would happen at the wheel, but I am not sure.
     
  16. mantasisg

    mantasisg Registered

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    @Yzangard Interesting, I have not read it yet. I should reorganize time a bit, post less in the forum lol.

    I have also read that heat alone does not hurt tire that much, I read that it becomes a factor when tire experiences significant centrifugal forces and fatigue stresses. Not sure if Michelin documents same thing.

    Interesting stuff about friction frequency, haven't heard that term, but I guess I know what it is....maybe. Tires does work in kind of "frames" when the, so called, slip angle happens. It might not mean tire sliding completely, but rather generating torque in, so called, slip angle. It also makes sense if there is such a rule that the higher that frequency is, the higher will ideal temperature be, could it also be by some chance that it also means that ideal slip angle would be smaller ? I suppose it is interesting document, must read...

    It could be this thing maybe, here with demonstartions


    By the way in the slowed replays in rF2, it can be sometimes seen how tire is twisting around its vertical axis when in slip angle. Perhaps it can be seen even too well :D
     
  17. BT7 Driver

    BT7 Driver Registered

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    I do not use Motec or Lazza's plugin, so I can't comment on the Vertical G channel specifically.

    @Lazza - Are you able to confirm how that channel is derived? I do not see it in what's provided by the rF2 telemetry API.

    I use only the API in my telemetry capture program, so the nearest equivalent channels would be Vertical Acceleration expressed in either the local (vehicle) coordinate system or the world coordinate system. rFactor 2 doesn't provide the world coordinate channel directly, but it's derivable by taking the dot product of the local acceleration vector and the vehicle orientation matrix, which is what I do in my program.

    For a vehicle at rest or in vertical free fall, it doesn't matter which coordinate system is used for Vertical Acceleration; they are equivalent. These channels can be converted to Vertical G by dividing by the nominal acceleration due to gravity.

    For a car in vertical free fall, Vertical G will be equal to 1. For sims that spawn the car into the world by dropping it vertically, this is exactly what is seen in telemetry. iRacing is an example, as is the sim whose telemetry plots I showed earlier in the thread.

    For a car at rest on a track surface, the downward force due to gravity at each tyre contact patch is counteracted by an equal and opposite force exerted by the track surface on the tyre. The net resultant force for each tyre is therefore zero and that is why the car's vertical velocity and vertical acceleration are both zero for a car standing at rest.

    Lazza's plugin is therefore reporting exactly what I would expect it to and any 'base adjustment' change as suggested would be an error. The suggestion is resulting from a misunderstanding of the physics involved. Be fully mindful of Newton's second and third laws of motion when trying to make sense of the physics:

    https://en.wikipedia.org/wiki/Newton's_laws_of_motion

    I would be astounded if rFactor 2 or any other sim had made the gross error of modelling the acceleration due to gravity incorrectly. Anyone with access to sim source code can of course check the value of this constant easily.

    There are some sims that have been modded without access to source code, where the acceleration due to gravity has been recovered using reverse engineering techniques. Grand Prix Legends is an example and was found to use a constant that closely matches the nominal acceleration due to gravity.
     
  18. Yzangard

    Yzangard Registered

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    I was maybe a bit misleading : my comments were only about finding the exact weight of the car when not moving, so the only force applying was gravity. We have tire load and with that we can find car's weight but when I used the channel from Motec, I had 0, just because I didn't took into account gravity.

    Was looking for car's weight because some ppl thought the car was "too light", which is clearly not the case, at least in telemetry.

    What Lazza's plugin is showing is vertical acceleration which is 0 when car is on the ground, motionless, for the reasons you explained.
     
    Last edited: Feb 3, 2021
  19. Lazza

    Lazza Registered

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    Funnily enough I saw mantasisg saying that in several places and I didn't believe it, but only got to testing last week. I intended to correct him on it, but my test confirmed it :p

    I found the easiest test was a range of (100000,1000,2), so 2 options of 100000 and 101000. So detached would be massively different handling (that ARB value is spincity!) but with the detached enabled the handling doesn't change.

    Anyway, off topic, sorry.

    On the exchanges with Yzanguard, there's a difference between questioning something and actually casting doubts based on those questions. On his point, it's absolutely possible for there to be an error in code, but that's always true. On whether a particular base should be used, he understands it's of no consequence either way. So why suggest it might indicate a potential problem when that just fuels the rumours? (as it turns out, as explained above, it's probably my value :eek:)

    Slip falls from a loop of unknown height and takes an unknown (unmeasured) time to fall to the ground, thinks it took much too long (based on.... ?) and then suggests gravity might be wrong, because it supports his theory on car handling. Except it doesn't, and when someone points that out the questionable gravity is forgotten.

    That's the sort of reasoning that makes up a large portion of these threads. But there is some valid reasoning in them too, I just want to encourage the good stuff and keep out the bad where possible.
     
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  20. David O'Reilly

    David O'Reilly Registered

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    And acceleration.
     

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