“ are rfactor2 physics broken” video

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

  1. Nieubermesch

    Nieubermesch Registered

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    I mean normal, default setup. Remember this car comes out of the pits with tires up to temp...



    Play it at youtube, extended view. Quality sucks.
     
    Last edited: Jan 25, 2021
  2. Yzangard

    Yzangard Registered

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    Tyre pressure itself can cause a 2 sec difference.
     
  3. Nieubermesch

    Nieubermesch Registered

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    I know that. That's not the point. I also am not good enough driving like a maniac...
     
  4. Nieubermesch

    Nieubermesch Registered

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    I would like to welcome people to try the following mods and tell me what you think compared to simillar ones from Studio 397:

    Acura ARX-05 - from Advanced Simulation
    Ferrari GTE- also from them
    Ginetta LMP1-also from them

    Actually, try all of this guys mods and the last Super GT cars.

    Have to say in the studio 397 tires, the problem seems to be that somewhow the contact patch can deform to crazy lenghts while some of the modded tires have probably the same grip, because elasticity is not as high, they can't mantain crazy slip angles!! The tires seem to feel too deformative and elastic (just like Slip Angle described before). That surely has to have and effect on slip angles. Since it's a physical thing on this tires, it seems it can support so much grip that the contact patch will probably assume shapes that no one ever thought possible. I know how they are supposed to deform, but what I am feeling and with all the information and videos, it feels like it's taking a shape very long (longitudinal) and too much force is being generated at the front of the contact patch, wich I think isn't that realistic (watched a bit of Aris video on the matter).

    Now I think I see why the Marussia F1 feels so wobbly, the tires really are getting so over reactive with the elastic forces of the tires, because they are deforming like crazy. This car has always felt so freaking planted (yes, even compared to an F1 machine). They went insane on the grip of this car even at low speeds. Just try this thing. Yes, it's snappy as hell, but while one would think that this means it has nothing to do with our problem at hands because cars aren't snappy enough, it's actually the other side of the coin. It seems to me there are two probelms at hand with Studio 397 tires. They are not completly broken, but this rubber I don't exists in reality. Maybe some rubber in the future will be created, but it's insane to be honest.

    I even think I can explain why Spinelli talked to badly of some of the cars. The front remains with some much grip at crazy angles and they don't lose the grip, making the car spin really sharply, instead of some of the front tire skid helping, at least in some moderate speed corners...

    I've read somewhere that slip angle is not really something inputed into the parameters of the tire. They said it was a direct reply from ISI in 2015. Anyone can confirm this to me? Slip angle will still exist, but since it's being naturally created by the physical properties of the tire and the car physics/aero, than what I said I believe makes even more sense, as I would guess the softer/elastic the tire is the bigger the slip angle can be, since it's related to the contact patch.
     
    Last edited: Jan 26, 2021
  5. Remco Majoor

    Remco Majoor Registered

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    that is surface temp though, not sure if the core temp comes out warm too
     
  6. Havner

    Havner Registered

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    You mean the one from RSS? I just tried. It's not much better. The default setup is very oversteery, but make it understeery and you basically can drive the same was as the official S397. For instance on Spa I can got full throttle mid corner 13 and keep it flat through the rest of of 13 and full 14 (Fagnes, the two turn "S") overturning the wheel on corner entry and controlling the slide if I loose the rear (the more understeery the setup the less chances to loose the rear). I don't know how to do such a thing in ACC. Maybe it's possible, I can't. In RF2 I can easily.
     
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  7. Nieubermesch

    Nieubermesch Registered

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    Probably didn't test enough. I've been playing with official content the same. Tire pressures are probably the issue. They are mostly minimum in lots of cars for now and when I put them higher they feel much better for me.
     
  8. Havner

    Havner Registered

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    Yes, also I lowered pressures to 140 as this is what the official content runs on. Forgot to mention in the previous post.
     
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  9. Nieubermesch

    Nieubermesch Registered

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    Yeah, I tried that after I posted this. It may be more of a core issue than one is giving credit for, even if the numbers can be massaged to be realistic, maybe people are putting realistic numbers and at some states tires don't behave as should, like low tire pressures.
     
  10. Nieubermesch

    Nieubermesch Registered

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    I made a mistake. The ginetta LMP1 is from Global Endurance Modding.
     
  11. Nieubermesch

    Nieubermesch Registered

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    Alright, I just rolled back a setting I had in the controller file, one that changed the type of steering force or something, that has the option between friction and damping. I quite liked it at the time, but now that I rolled that back I no longer feel the same lightness of the steering when driving around the peak slip angle and certainly now I can see I wasn't feeling the tire flex as much as I do now. It doesn't change some complaints and issues, but I have to report that a nagging issue is solved here, although I am sure no one really tried to change that setting at all :rolleyes::confused:
     
  12. Flaux

    Flaux Registered

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    I use steering dampening for years... but cool that you could solve an issue! :)
     
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  13. RaceNut

    RaceNut Registered

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    I've experimented with both methods but, settled on the default. As with quite a few ffb changes, they make things feel different but, not necessarily better. ;)
     
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  14. Nieubermesch

    Nieubermesch Registered

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    Yeah, I now know why I was feeling more slide before I should, between the state where the contact patch is gripping well but other parts are actually skidding and now it feels more natural. Feels good too, that now I feel the tire flex more, I didn't even remember that that was one of the side effects.

    Still, I want to recommend people to play with the Nissan GT-R GT1 and see the tire wear of this cars. Not sure if they are overdone, but they certainly wear very fast driving like a maniac and they really get hot and temperatures don't dissipate so easily from the surface.
     
  15. Kelju_K

    Kelju_K Registered

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    About how much drift is drifting?
    @Bruno Gil "if not at opposite lock, its not drifting"

    i completely disagree. if all 4 tires are pointing forward but you are sliding almost doorhandle first in to the apex, thats drifting for me.
    thats what the "scandinavian flick" (rally driving technique) is for, to flick the weight of the car to drift, not kicking it with throttle and keeping it in hands with opposite lock. No opposite lock is needed if the "flick" is correct. rally drivers are not at opposite lock that often you know.

    i find my self doing the flick to aid in cornering (zandvoort turn 4 for example), and to correct braking mistakes (if i went bit long in the braking). this something that these cars (porche cup) shouldn't allow, at least not in that amount that is possible in the game right now. this is not rally!

    And to what should be done to correct this behaviour? well.. allowing 110kpa minimum pressure is just... i mean that is just 1.1 bar.
    0.1 over ambient. there propably are some race cars than can be driven with this low pressures, in some tracks, but still it would be dangerous i think. even when warm pressures are obviously higher that 110kpa.
    so what to do to correct this? 115kpa minimum would do a lot already. Usually my setups that i feel make the car (p cup) behave at least somewhat believably have front pressures around 120-130kpa and rear pressures around 115-117kpa.

    BUT i do have to eat my words a bit here.
    I dont get the fastest times with crazy drifting, but i have to make a setup that allows crazy drifts, and allows to catch the drifts from waayy too long drifts and high agles, but then not drift it, but only let it slide gently to get the fastest times.

    So i dont think the tire model is not that far off that my initial post might have made people think.
    AND i do not even blame S397 about the flaws.
    The model is based on that infamous ISI CPM model that was the hole in the isi ship that sunk it. So what was left to S397 hands when they took over was a catastrophe to begin with. but still. these tiny flaws have too big impact on what you can do with the cars now. you can catch too long slides from too high agles with the current model. Which in turn allows other tricks (the scandinavian flick etc) that are not road racing techniques, at least not to extent that it is usefull to use them in particular corner every lap to gain time.

    And to be clear. i blame the tire model only. i dont believe that detaching this or using zero toe etc are exploits at all.
    its all in the tire model that make these cars too easy to drive, and allow things that they shouldnt, at least not in the same setup that is fastest or close to being fastest.
    Setup that allows that sort a stuff, was about 2 seconds slower than setup that gives best times in ISI cars. now it's too close to put it short.
     
    Last edited: Feb 2, 2021
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  16. mantasisg

    mantasisg Registered

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    Not true. You can make tire that behaves in great amount of different ways in rF2 thanks to ISI underlying physics. Also good underlying physics is the reason why rF2 FFB gets so much praise. Too bad people don't understand physics as much as they understand feel of torque in their hands.

    Have you tried making different tires in rF2 ?
     
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  17. Kelju_K

    Kelju_K Registered

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    ok. to be more specfic. i blame the current IN USE tire modelling in the gt cars. i 100% believe that betters tires can be made with the current model.
     
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  18. Jack Dyson

    Jack Dyson Registered

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    Just want to add my voice to the physics debate : in all cars, either too much grip (modern slicks), or too little (radial type). You can drop the pressures and increase grip levels so that it becomes possible to go 1 to 3 seconds per lap faster while also improving the handling. The sensitivity of the car to setup is reduced when this happens. You can drop the ride height on deflated tyres and generate yet more performance.

    The aero model has just two wing parameters - for all the cars : why?

    The FF is not generally well resolved especially when tyre pressure is low and it is hard to tell what the car is up to; you feel bumps and bounces but even though the sidewalls feel normally compliant, the FF acts as if they are indeed collapsed (mushy for want of a better term). Different car models do not exhibit very different FF. Interestingly, the video representation of low pressure tyres shows them to be flattened.

    Generally, on cars with slicks and no aero, the road holding is superb - I know from having driven in real life it is an excessive amount of grip - I can almost do what I like and it will not send me into the barriers. Mechanically gripped machines with radial tyres have too little grip (e.g. the BB20 has less than it's GPL counterpart, and that was known to be too little) on the other hand. Another example is the Reiza Formula Vee - I know the free differential contributes to the effect but looking at youtube onboards and laptimes I get the impression that the tyre itself creates more grip on the road.
     
  19. Lazza

    Lazza Registered

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    @Jack Dyson that's a lot to unravel, but given you're relatively new to the game I'll just ask about a couple of things:

    Grip based on handling, or on performance? There's usually a disconnect between what people see in real life and what they feel in a sim; the number of times there are complaints about lack of grip with an actual "should do x.x g in the corners!" reference - in a car that telemetry proves does achieve that many g in corners - might surprise you. The opposite is also true when people haven't yet found the limit.

    Not sure I really understand, but the aero parts are front wing, L/R fenders, body, diffuser, rear wing.

    Do you want more separate items? Would there be a benefit in terms of handling? Or is this related more to damage modelling?
     
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  20. Jack Dyson

    Jack Dyson Registered

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    Hi Lazza, thanks for your reply!

    I agree - suggestion: basic integrated telemetry would be a good thing to have in the future on RF2. - I can't say much about the telemetry as I have not looked at the Motec output for every lap yet : this is just by feel in races and hotlaps.

    I'll try to answer the first point by saying :
    ---------------------------------------------------
    grip based on tyre stability : I mean that in the sense of divergence from the racing line. While I will admit freely that I have yet to find my ultimate limit (I can't feel the tyre slip in RF2 for some reason, but I am generally about 0.5 to 1 sec faster than the 100% AI). Supposing that I am fast enough - I can vault into a medium fast corner and the induced oversteer is forgiving on a slick so that I survive it. If I do the same thing on a radial - even a just a little : I usually end up in the bushes. This is a general observation across many cars.

    In the stability sense, irrespective of setup (more or less) :

    1) a small steering input on a slick at the limit causes a small deviation from the racing line --> stable

    2) a small steering input on a radial at the limit causes a large deviation from the racing line --> unstable

    3) a small steering input on either type when it is deflated causes a small deviation from the racing line --> stability convergence

    Ok I hope that gives some idea of what I am seeing. If you will forgive me - I think something is not working correctly on that tyre model - the grip in any tyre should be dependent on setup and at the limit all tyres are unstable : the "cliff" beyond a 7 degree slip angle on the rears. Throw a machine into a corner hard enough and it should bite you back hard - on RF2 : not always the case.

    Now for the second point:
    ----------------------------------
    Yes I would like all those items separated please - for both damage resolution and handling: I don't know if you use distributed body force meshes on those elements, but including them in that way would really affect the handling on fast aero machines and the mechanical/aero grip cross over behaviour. It would also exploit the dynamical superiority that RF2 has built into it and make it quite unique.

    The setting up of aero machines would not be a simple one dimensional "drag" factor problem, it would have effects on the mechanical/aero grip compromise in a detailed way.

    The damage modelling would be fantastic - e.g riding the curbs hard during a race and getting understeer on one side because half the diffuser is gone....

    Thanks a lot for listening !
     
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