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. ATQ

    ATQ Registered

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    It's a most excellent video but the curve he's showing should not be taken as the real slip angle curve. What it could be is one tire as measured by one manufacturer, to perhaps 10 degrees of slip. A different but very similar tire could have a very different curve, at least according to the data. Niels Heusinkveld talks about real tire data here, and shows just how different the curves can look.


    Yes, that's interesting but the data isn't conclusive. The slip angle curve changes with load and combined lateral and longitudinal slip. Peak grip can shift to a much higher slip angle and gentle drop off - even to the point of peak grip being with the tire going completely sideways. Overall grip would decrease, at first by a little and then by a lot, so the peak you get under certain conditions is not necessarily the maximum amount of grip you can get out of the tire.

    So you see, maybe your results here look strange because of the assumptions you make on how the curve should look? It could very well be that the results are spot on. Again, Niels talks about it here:


    Actually, you are losing grip. A few percent, so it's not huge, but still. Question then is, what would the data from a real car look like?

    Understeer being a bit slower but much easier to drive certainly makes perfect sense. If it's not punishing enough, then how punishing should it be? We don't know...

    Maybe it's exactly as it should be? Of course it could be wrong as well, but it's not exactly obvious that there is a problem here.
     
  2. Yzangard

    Yzangard Registered

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    Very interesting ATQ and out of curiosity I will do some more testing but my problem now is not to know what is going on and why are aliens using techniques that aren't in use RL (there are some other parameters we already talked about like what we actually feel as simracers, what we can chose to NOT feel, like huge FFB reactions or vibrations, etc...) but the bottom line of all of this is that some ppl already did all this work and S397 chose to not listen to them, so all I or you or whoever will do now is for ourselves, it won't change anything (assuming there is something to change of course).

    I took a step back since yesterday but it keeps on obsessing me, I don't like when I don't understand something, I don't pretend to understand every physics aspects of a race car of course but this simple question boggles me : why can aliens in game use a technique that real track aliens never use ? Maybe it is POSSIBLE to do but consequences are so huge that they actually don't take that risk or even simpler, with real life "ffb" it is simply impossible to do ?

    For the moment, I don't know but this video is interesting, indeed.
     
  3. Comante

    Comante Registered

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    I don't think it is worthy for your brain to waste energy with such questions, it's extremely futile. The real world has more rules to apply than just physics. A driver has a contract with a team, the team want their car to end races, ALL the races, possibly ahead of others, a team has contract with sponsors, they too want something, but on a thing all 4 agree (the 4th is race director): we don't want a pile of crashed cars.
    As I already said, there is a level of unpredictability in real life that make reach an absolute limit risky and unworthy. In a simulator, such unpredictability doesn't exist, and there are not costs, teams, sponsors or race director to upset. This mean that you can exercise and tune to a level that is impossible in real life.
    For example, I was watching this video of Risto Kappet making a car setup: he made a few laps, checked telemetry, changed one or two parameters, made another run (burning the motor to find the smallest radiator size), rinse and repeat.. for probably 1 hour. Now, How many days in real world would be necessary to conduct such activity? At which material cost?
    I've noticed (in my past league experiences) that often fastest drivers are just qualifiers, then they struggle to end races. Would a driver like that have a career in motorsport? I highly doubt they will last more than 2 seasons.
    It is not much different with combat flight simulators: Fighting a war following combat protocols to the rule can be quite boring, so we do thing that we would not do in real life.. who cares, our planes cost nothing, our life is not at stake, flying fast and low dodging bullets is fun, circling at 30K feet dropping Jdams is quite boring. Can you see what I mean?
    There will never be a game that will perfectly mimic real life, even if physics wise would be 99% accurate, you will still engage in unnatural behaviours.
     
  4. Flaux

    Flaux Registered

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    What consequences? Go out on a rainy day and overdrive your car. At some point (of steeringangle) it will not gain anymore grip it will stay at an almost constant level of not perfect grip. The question with rf2 is simple. Is that optimal grip range where it belongs, or is it off.

    PS: As Niels said. Simplify to understand stuff better.
     
  5. Yzangard

    Yzangard Registered

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    Real pilots are risking their lives all the time so I don't think fear is a real parameter, if a technique is faster they would use it no matter what...and if it is faster and doable, they would set the car so they can do it without destroying the car. I think the reason they don't is that somehow it's not effective.

    Don't worry for my brain, it is used to "overstress" because of my job anyway. That being said, I'm pretty sure don't worry very much :)
     
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  6. Yzangard

    Yzangard Registered

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    It is precisely what we are doing, isn't it ?
     
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  7. fireballR18

    fireballR18 Registered

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    No idea what the truth is, but to me the tire model of ACC e.g. is more believable. This technique to being quick looks like a bit of an arcade move, but as I said: I'm not able to justify in a proper way. My answer is no for what I understand.
     
  8. Flaux

    Flaux Registered

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    Absolutely and it took only some weeks and 3 or 4 threads to get to this simple point. At least that is what it felt like to me... lol.
     
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  9. Slip_Angel

    Slip_Angel Registered

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    Answer is very simple, such technique in these cars are never seen in all the thousands hours of onboard video i watch.
    So it is pretty obvious that this is physics/tire issues that needs fixing.
     
  10. Slip_Angel

    Slip_Angel Registered

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    3 to 4 thread because many people refuse to believe it as a problem.
     
  11. Flaux

    Flaux Registered

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    Yeah, it was a mix of venting, language-barrier and defending of what we have right now, I believe. And some where just happy to write some stuff off of their shoulders, which is absolutely fair in my book. We are such a patient and loyal community and should be allowed to do that from time to time. :)
     
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  12. Yzangard

    Yzangard Registered

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    Just did the same test I did yesterday but this time with "correct" pressure (by "correct" I mean what is used in ACC, so approx. 185 Kpa once hot) and guess what ? It is close to impossible to handle the car with clear oversteer technique, I spun almost each single time and lost a lot of time the rare occasions I managed to not spin (FFB was what I use usually, I didn't lowered it to be able to handle the car more easily)...

    Underpressuring tires is not an impossible thing to do with real tires (all F1 teams are using lowest allowed pressure almost all the time for example but mainly because regulation imposed a minimal level) but it should have consequences on car handling and tire degradation.
     
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  13. ATQ

    ATQ Registered

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    I've been running ACC for the past couple of days and what strikes me is actually how similar it is to rF2. Biggest difference is the force feedback, where both do a good job. Otherwise it feels like ACC has maybe a bit more bite to the tires, but rF2 tends to bite down more when you flick the car. Both have a gradual loss of traction with the GT cars, and drops off quickly if you push it too far. It's fairly easy to overdrive the cars and catch slides and I would be surprised if the same techniques didn't work in both of them.

    I find it intersteting how similar they are considering they use two different approaches to tire modeling (physical vs. empirical models).

    The technique of understeering by overturning the wheel seems to be common in sims. Don't know if it works in ACC but, as I said, I would be surprised if it didn't. I've seen it used in AC. Project Cars 2 has it more than any game I've seen. It's also rather popular in Dirt Rally 2.0.

    I find it curious that several different approaches have arrived at something similar.
     
  14. Kevin van Dooren

    Kevin van Dooren Member

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    @Yzangard What cold pressures did you use and I'm assuming you used a GT3 car? As with most GT cars we do reach around 185 kPa hot pressures with the minimum cold pressures.

    Btw, I'm aware its a bit of a nitpicky thing, but your comparison of the slip angle behavior of two different cars is rather an inconsistency and not a comparison. Since both the channel on the vertical axis and the dataset/car are changed, you cant distinguish which of the two causes the differences between the graphs.
    When doing the curve fits, you can also see the coefficient of determination (R^2) by checking the show equation box. This can be quite a useful tool when determining the order your polinomial for example.
     
  15. Yzangard

    Yzangard Registered

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    Jardier is often using this overturning wheel technique on some corners but in a more controlled manner. So yes it is possible there as well and I know for sure from a real GT3 car driver (my former boss to be precise) that it is possible RL as well but not that efficient.
     
  16. Yzangard

    Yzangard Registered

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    It seems to me that I was around 155 Kpa cold. Yes when hot it gives the same pressure but for some reason, the behavior quickly becomes very different. And no, in this case it is the Porsche 911 RSR, a GTE.

    I forgot to specify that my times were the same as the ones I had when I lowered the pressure, I just needed more precision in my driving but clearly feasible.

    Concerning the graphs, I didn't present exactly the same ones in the post I made but I have both at my disposal, it's just that I chose to show others to highlight another point: the fact that choosing the lateral forces of the car as a whole or the ones applied on the wheel under stress gave almost the same kind of graph, the goal is "hidden" but it has its importance for some people :)

    Anyway, the idea was not to strictly speaking compare the cars with each other but rather to check that the behavior was common to several cars.

    Will post results with the equation if you need it, but will do some more testings :)
     
  17. Stefan_L_01

    Stefan_L_01 Registered

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    Of course you can move your wheel to any pos.
    Dont forget that the drag you create by slip angle is a function of v^4. This huge drag at high speeds countetacts the steering as the Moment works the other way around for the car. So you wont see it for high speeds in reality because the small gain in lateral grip once you exceed 5° is lost by the drag moment. Not speaking about burning your tires in few seconds...
    I think we should not look at the peak. If you model a slightly curved plateau for slip angle, you may get a max at 15°. Yet the difference to 5° can be very small and as said neutralized by the drag Moment.
    I think the stiffness of the slipangle curve, the steepness in the linear section, is more cruical for a realistic feeling.
    Furthermore we should not forget that slip angle should not be an input for a model. It should be the output or result of a complex contact patch simulation
     
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  18. hitm4k3r

    hitm4k3r Registered

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    How do you come to the conclusion that fear isn't a relevant factor in this whole discussion? I would say it's one of THE factors that seperates playing a computer game vs. doing a real four wheel drift in a 1 Mio. car through 130R and putting your life at stake just to "try" something that you've never done before, yet it doesn't seem to get into the brain of most people here that there are so many surrounding factors in real life compared the virtual world that you will never be able to replicate the real sensation wich also explains why you see wierd driving techniques in racing sims. Who came up with the idea that this is just a rF2-thing? I could lough my a$$ off about a guy who throws the Senna GTR around Suzuka and wonders why he can do things that you don't see in reality or a guy who leaves the competition system to have a better time in AC1. I mean, how hard it is to comprehend those things and Comante actually put the finger on the right spot. Even if real pilots risk their live on a daily base, they will never push the plane to the extremes that Comante explained. That's the important difference. There is something like a subconscious and a basic instinct to live. Do you really think that people can switch it off in reality like they can hit escape and restart a session in the virtual world? Don't be naive.
     
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  19. Yzangard

    Yzangard Registered

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    Not only this but if I trust this paper the data obtained from manufacturers are often limited to a certain slip angle, beyond that it is often inference and therefore no model can claim to be "realistic" more than another, at least not when comparing with manufacturer's data.
     
  20. Yzangard

    Yzangard Registered

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    You are over-interpreted my words in fact, I was only saying that the real drivers already have this permanent fear of the accident, they live with it and their job is precisely to take risks to go to the limit of what their car is able to do, so if an efficient technique existed they would necessarily use it after having learned to limit the risks... if they don't do it, it's probably not because of this fear but probably because it's not efficient, or because the "gain versus risk" ratio is not interesting.

    It is more than obvious that in a simulator this fear does not exist and therefore we do not hesitate to take risks that we would probably not take in real life.

    Having said that, it's a pilot's job to take these risks and I really doubt that a professional pilot takes the wheel with fear in his stomach, they live with risk all the time but not with fear, otherwise they stop performing.
     
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