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. Comante

    Comante Registered

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    It's not about "fear in the stomach" is about get the job done. The job of a pilot is not to take risks, is to end races. Just like the job of the combat pilot is not to blow stuff, is just to return the plane at the end of the mission.
     
  2. Yzangard

    Yzangard Registered

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    Well, aren't we saying the same thing actually ? :)
     
  3. Comante

    Comante Registered

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    Look I don't want to be harsh but pilots that dismiss risks are dead pilots . Gilles is the first that come to my mind.
    In aircraft world there is a saying: there are 2 kind of pilots: bold pilots and old pilots.
     
  4. Comante

    Comante Registered

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    Yes maybe is just the language barrier.
     
  5. BT7 Driver

    BT7 Driver Registered

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    Interesting discussion when the hyperbole dies down.

    A suggestion for the thread. I see the word ‘oversteer’ being used in an non-standard way at times. In race vehicle dynamics the word has a specific meaning - rear tyre slip angles larger than front tyre slip angles. The behaviour here involves application of excessive steered angles at the front tyres, hence front slip angles greater than rear. That is an understeer state, applying the terminology correctly. Yet, curiously, this state does not appear to impair cornering ability, contrary to expectation from real life.

    This behaviour, or something resembling it, is present in multiple top-tier current sims. ACC has been mentioned. There is at least one other. Very surprising, given they all use different tyre models.

    A proper analysis of this behaviour and comparison between sims, and between different cars and tyre types within one sim, is best done, in my opinion, using controlled tests on skid pans, assisted by telemetry. I would suggest using a computed channel = yaw rate divided by front wheel steer angle as a starting line of investigation. For those of you that have a copy of the book, that is the yawing velocity response to control measure described on page 154 of Race Car Vehicle Dynamics, by Milliken & Milliken. Please note that it is intended for use in steady-state cornering analysis, hence my skid pad suggestion.
     
  6. Yzangard

    Yzangard Registered

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    Maybe, wondering because when I read you it is exactly what I meant and tried to explain :)
     
  7. Yzangard

    Yzangard Registered

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    I admit that I have already had to change my words because of this story of turning the steering wheel excessively and thus causing an understeer. I try to be precise when I talk about it but clearly it can be confusing, especially as I translate my thoughts since English is not my mother tongue and my low level must be obvious.

    To do the tests I would have to use a dedicated circuit but the only one I could find "crash" often when I launch it, so I took refuge behind the use of a short oval (I would have to find Charlotte's "Legend" version but I haven't looked for it yet).

    In this document (http://www.sim-racing.co.uk/pdf/Tires-in-race-simulations.pdf), Niels explains why anyway these curves and graphs are not a good answer, the main reason being that these "curves" are actually not curves at all, they are a generalization of a much "fuzzier" model and anyway a car being subjected to a lot of other sources and constraints, these curves will never be found exactly. Not to mention that usually manufacturers limit their study to something like 12 to 15° slip angle.
     
    Last edited: Jan 27, 2021
  8. Stefan_L_01

    Stefan_L_01 Registered

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    Why bother with more slip angle? Your front wheels (tire) rotate by <20°. The c7 is modelled in rf2 with only 12°.
    There is no real need for slip angles > 12° as there is still some dierctional change.
    You could also say 12-15° slipangle covers well the range of all possible wheel (tire) deflections.
    For a super heavy tail drift i do not really care actually.
    Nils was taking about 40°slip angle issues, sry this is making donuts. Nothing what is of major interest in first place
     
    Last edited: Jan 27, 2021
  9. Slip_Angel

    Slip_Angel Registered

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    ACC does not suffer from such techniques and neither does iracing.
    Every hotlap videos i saw with these 2 games the steering input looks normal.
    Even though i'm not alien i got quite close to alien time in ACC and i tried such exploits there but it never works.
    It can be "used" in both sims BUT the punishment is severe as it should be.
    Not to mention such technique are not seen in IRL qualifying onboard as well.
    So this leave RF2 alone with this exploit.
    This is 3:1 ratio where RF2 is outnumbered by 3 evidences , i think this is enough proof.
     
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  10. ATQ

    ATQ Registered

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    This is literally the first video I found when searching youtube.
     
  11. Slip_Angel

    Slip_Angel Registered

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    It is nowhere near rf2 level. And if you observe little bit better you can see he is getting punished DESPITE not going to RF2 level steering input...
    Oh and also this is with old tyre and aero physics
    You wrong.
     
  12. Nieubermesch

    Nieubermesch Registered

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    LOOL.

    Man, I think you would be one of the idiots that at the time that Studio 397 changed their model that everything is fine, some things are only being possible because of absence of fear of death and bla bla bla... I mean, the other day you had the audacity to suggest that I simply should have listened to you as if you had the answer, saying something of the sort like "really, after all that I told you?". Well, now it would be of good faith to drop some of the reliance on the fact that there is no fear of that, because the problems lie in a different place, because you don't even seem to understand, that the thecnic of using understeer and turning is actually safer than pushing on the egde.... So try to think more and drop some of the ideas you guys try to hold on to to defend the simulation, when the conversation has taken different turns and those things have also been considered... We are seeing different problems, it's not just about what happens after the limits. Anyway, tire pressures as aknowledge by Yazngrad play a major role. It's what I did in my videos, for god's sake. Get a grip and I never insulted anyone here before this, but you're being quite annoying now.
     
  13. Yzangard

    Yzangard Registered

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    Jardier is still doing it quite often but in a more "legit" way, I mean this is not an impossible move by any mean, it's not a crazy technique at all, it's even a technique taught in driving courses that comes more particularly from the world of rallies (turn the wheels sharply while braking and once the car is in the right place, release the brakes to regain grip on the front wheels).

    That said in ACC it's much more "subtle", clearly less pronounced as you say and it's above all done to reduce the speed of the car by braking less, almost a kind of soft braking to reach the limit more precisely...I don't know, I don't use this technique because in my opinion it destroys the tires and in rF2 the vibrations make the driving so uncomfortable that I don't think I'll use it one day anyway. It turns out that now ACC has also added vibration in case of flat tire so we will probably see less and less use of it.

    I still think it's a bit too easy in rF2 to use it (this video from Le Mans is just unbelievable) and it's too easy to forget the vibrations by artificially lowering the FFB.

    That said, I don't think it's a huge problem either, just something abnormal. This story of under-pressure in the tires seems more worrying to me.

    Just realised that another aspect of what my results shown is overlooked here : tire temp doesn't seem to affect grip at all...I mean I have tires going above 200°C and they still grip like crazy as if they were at perfect temperature...maybe it is the core problem actually, and the reason why lower pressure is better than higher one, and why this steering technique is so efficient ?
     
    Last edited: Jan 27, 2021
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  14. mantasisg

    mantasisg Registered

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    Looks bit more subtle IMO, but also not a gold standard. Even if ACC is marginally better and Aris does amazing job combining realism and likeability. Still. Reality is a gold standard. Change my mind lol



    Look. More quick catching. More driving at optimal slip angles and ratios. Driver works hard. Driver is professional. Looks exciting, because it is. Car has lots of subtle movements. Pole laptime = fastest. No stupid understeer tire dragging 50s driving techniques that wasn't even that blunt in 50s. Planted. Lots of tire bite. Sliding is not beneficial.
     
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  15. Flaux

    Flaux Registered

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    You are watching a video, Sir. Don't get that mixed up with what reality is!

    :p:rolleyes: Just joking of course...
     
  16. Yzangard

    Yzangard Registered

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    He is clearly using the same kind of technique but way more subtle, more or less like aliens are doing on ACC.

    I'm starting to think that the issue is tire temps that aren't punishing at all, you can burn your tire (almost literally) and still have a lot of grip. This makes the low pressure and the over turning wheel work very well. Make the tire lose grip and wear at higher temps and maybe it will change ?
     
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  17. Yzangard

    Yzangard Registered

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    Reality is not very realistic nowadays :)
     
  18. Lazza

    Lazza Registered

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    From what I've seen in the various videos it does impair cornering (from a yaw rate perspective), though it obviously doesn't make cars slide off the track (how often it should is a matter for debate, but I think generally is overestimated).

    What seems clear is that the tyres maintain performance too well in this scenario, and that would appear to be backed up by the "sliding" videos showing the same persistent grip at the rear.
     
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  19. AMillward

    AMillward Registered

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    Because iracing puts you in a wall if you get more than one degree of slip.
     
  20. mantasisg

    mantasisg Registered

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    Low pressures is something else, hard to define, perhaps it has play at this, but I think it is not a critical point. I have my theory of net friction and grip composition. Realistic net grip level gives realistic laptimes. But net grip can be composed in different ways. For example there can be plenty of static friction and little sliding friction and vice versa. The key to "Easy side" physics seems to be lowering static friction, and increasing sliding friction. This way tires are more "slidable", not too fast to correct the car when it goes over edge. The downside is that car might become not as planted as it should be. Other tire factors such as tire stiffness has a say at how fast the tire can snap off or bite in, I wonder how to see that in telemetry, generally as much as I know those things result in higher cornering stiffness which is shown by how steep the slip curves are.

    If once by some method we could accurately prove that tire static friction is not high enough, or we could look for ways how to tell if sliding friction is too high and for what reason - heat sensitivity?, velocity sensitivity?, tire rubber shearing off? Then it would be really awesome. Tricky part is that operating tire works at sliding and at static friction together. In fact slip curve essentially shows at which point tire has best combination of these two friction components, as with increasing slip angle static contact patch area decreases, and sliding contact patch area increases.

    iRacing punishing physcs also fits into my theory. I keep on noticing that the quickest iracing laptimes are a lot faster than RL fastest laptimes. Laptimes are direct functions of net friction. They must not slide, if they manage to keep tires supper efficient at not sliding aliens are able to do insane laptimes in iRacing. Thats also the reason why it is difficult, it is hard to keep tires away from overdriving when forcing them to go faster. I wouldn't even call this "my theory", because it is plain basic stuff, but no one talks about that lol Everyone thinks it must be something complex and difficult.

    I would not expect any of the studios to do anything else what they kept on doing for years, unfortunately, they know what they need from physics to achieve their goals. However, it is nice to talk about cars between us.

    Yeah, but thats fair to say even seriously. There are things to consider even when judging actual unedited footage of actual reality. But I'd propose an idea that it is in fact hardest possible evidence possible of RL physics - simply seeing how it works. Data - numbers, curves and so on... will be better at getting precise and understanding reasons better of what makes car do what it does. But really nothing there is harder evidence, than to simply see how it works, what happens and how. I think being able to look at the footage is even more reliable than getting an opportunity to drive yourself and then judge stuff by memory (although you'd probably have your own onboard footage, and wouldn't need to totally rely on memory).

    The bad thing about footage as an evidence, it takes light amount of effort to spot details, perhaps sprinkle of knowledge as well to be able explain yourself how to understand what is going on and to notice as well, because you need to know what to look for. For example I look at how much and how fast and precise steering is, listen to engine, try to see how chassis moves, try to see yaw angles: overturnign and underturning, how much of it happens and in what kind of frequencies, also in general driving techniques, and so....

    I generally think you can get fair idea of car handling by just looking at it. But many people don't know what they should look at, even simracers, who should supposedly be familiar with vehicle dynamics in practical way.
     
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