Poll: Is this driving realistic?

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

?

Is this driving realistic?

  1. Yes

    31.6%
  2. No

    68.4%
  1. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    Heres how much handful modern cars can be despite running on TC --->



    iRacing version of "similar" car -->



    No sluggish slided like RF2, no abnormal overturning of steering.
    Quick and precise correction of oversteer, No 4 wheel slides every single turn, no throwing the car like a rally car.
    You can see in both videos when car starts to over rotate it needs to be correct with correct amount of opposite lock.
    In RF2 to get to the point of needing to put opposite lock you literally need to be drifting....slides before this phase can be 4 wheel steered
    / drifted easily.
    This is painful obvious things for me, it doesn't get any clearer than this.
    Is iracing too much punishing ? maybe but i haven't seen these modern race car giving as much opportunity as in RF2. Not to mention in iracing atleast you NEED to used TC to not only be fast but to be safe because modern slicks have 5-7 degree of peak slip ...that's nothing, you are going over it quickly if you are not careful.
    RF2 i disable TC otherwise I will fall a sleep driving.
     
  2. BT7 Driver

    BT7 Driver Registered

    Joined:
    Oct 22, 2020
    Messages:
    14
    Likes Received:
    6
    Some expansion on what I wrote in my first post.

    ACC I have no personal view on. Of all the sims I drive, it's the one I spend least time driving (not a fan of GT cars). It might share this problem or something similar, it might not.

    iRacing I have driven extensively and it definitely exhibits behaviour similar to what is being highlighted here. That's based on extensive testing and analysis of telemetry in a total of 11 cars running various iterations of the tyre model from NTM6 to the latest state of the art. It's possible to see understeer balance ratios approaching 5x (front slip angles five times the rears) easily, with relatively little impairment of cornering ability, as measured from yaw rate and lateral acceleration.

    To better illustrate the potential value of what I'm suggesting, I've attached a telemetry plot showing the two response to control ratios (yaw rate version as described above, plus the lateral acceleration version) from a skid pan terminal plough test performed in one of my favourite sims - not ACC, not iRacing. The sim does not exhibit the cornering behaviour that is being highlighted in this thread. The car driven for this plot was a light formula racer (open wheeler). The intent of the terminal plough test is to force the car through progressively increasing states of understeer and to measure the effect on cornering performance, using the two response ratios, until the car reaches a state of terminal plough (terminal understeer).

    As I said in my first post, these response to control ratios are intended for steady-state cornering analysis, so please ignore the two big spikes in the plot. Those happened due to a partial loss of control (recovered with countersteering) because this test is very difficult to perform in the chosen sim and that is because (in my view) the sim does a good job of simulating fundamental aspects of tyre and vehicle physics.

    Structure of the plot:
    - Top area shows the front 'axle' slip angle (essentially an average of the two front tyre slip angles) and rear axle slip angle. Additonally, the dotted line (Balance_L2 channel) shows the slip balance ratio = rear slip / front slip (positive values represent oversteer and negative values represent understeer). The values are plotted on a base 2 logarithmic scale, so the peak understeer ratio observed, toward the right side of plot, is around -3, which means front slips around 8x rear slips.
    - Middle area shows the two response ratios. Ignoring the two massive spikes (car not in steady state cornering), note that the peak response values toward the left side of the plot correlate closely with neutral balance states (rear and front slips roughly equal). Note also, how the response ratios progressively decline as the car is pushed to progressively more extreme states of understeer. This area again uses a base 2 logarithmic scale, but note that a special plotting technique is used to allow plotting of both positive and negative values on a single logarithmic scale. In the test performed, all response ratio values are actually positive (car turning counter-clockwise), but the dotted lines in the negative plotting area represent positive values less than 1 (so -1 = 1/2 = 0.5, -2 = 1/4 = 0.25).
    - Bottom area shows driver control inputs and car yaw angle. Note how the terminal plough state was achieved with full throttle and full steering lock applied. The front tyres were of course howling in protest by that stage!

    For anyone who is serious about quantifying the extent of this problem in rFactor 2 and other sims, this seems to me probably one of the most effective ways to do so and most likely to provide actionable evidence for the respective sim developers. In short, it's a controlled dynamic scenario test, repeatable across multiple sims and for one sim across multiple vehicles and tyre types. It will provide quantitative measures of cornering performance impairment versus degree of understeer.

    Terminal plough test:
    Terminal Plough (With Response Quotients) - Comparison Sim 1.png
     
    Last edited: Jan 27, 2021
  3. ATQ

    ATQ Registered

    Joined:
    Jan 15, 2021
    Messages:
    47
    Likes Received:
    30
    Yes, I agree it's more subtle. My point, however, was to show that the same dynamic exists in ACC. The differences in how pronounced it is could be down to different drivers, or something else for that matter.
    I wasn't trying to use ACC as some sort of gold standard but rather to point out that it's interesting how many sims show the same dynamics. Even Dirt Rally 2.0 does that, and it's entirely different from the rest. It doesn't prove or disprove anything, but it's curious.

    I find rFactor 2 to best replicate that by a far margin. It's got lots of subtle movement, you can feel tires grip and slip and deform all the time and you have to work hard. But, that's also with a good wheel that provides decent torque (CSW 2.5 here, had a T300 before that and it didn't provide the same feel).
    Funny how what attracted me to rFactor 2 is criticized for not being there or too weak. I haven't got anything close to it from other sims - they tend to feel a bit dead in comparison. That's not to say rFactor 2 is perfect just that it comes closest to the real thing.
     
  4. Flaux

    Flaux Registered

    Joined:
    Oct 5, 2010
    Messages:
    948
    Likes Received:
    380
    Better not watch Wolf Kaufmann in a Porsche then... haha. I have never seen someone drive on and around the optimal steeringangle like he does. Sure the older 996 had a different steering ratio compared to the new cars with their F1 steering wheels... but it was and is still a cool video to demonstrate this technique.

    BUT: It doesn't show anything in regards to what a real tire-model feels like. So,...at least for me, data and specially the grip you feel in a real vehicle is way more interesting. That's why it is good to get feedback from real racers... (when you are prepared for the outcome, lol)

    Kaufmann in a 996rsr
     
    Last edited: Jan 28, 2021
  5. ATQ

    ATQ Registered

    Joined:
    Jan 15, 2021
    Messages:
    47
    Likes Received:
    30
    Heh, damn... that's what my 4 year old nephew looks like when he imitates driving (granted, the little troll can already drive dirtbikes so he might be on to something).
     
    Flaux likes this.
  6. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    I don't think we should compare with iRacing because as mentioned above, the ratio between static grip and sliding grip is reversed compared to rF2, when you see the way of driving in iRacing, it looks more like a balancing act than driving, Basically the drivers have learned not to exceed a limit otherwise they would lose their car, so it may look like reality but in fact it's mostly because the grip is so huge without slipping and suddenly becomes so weak when slipping that the driving becomes inevitably clean and smooth.

    The lap time in iRacing: 1:10...in reality, 1:17, there is something wrong too, it's just the opposite that happens: the static grip is huge, the sliding grip is very weak.
     
    Pawel44 and mantasisg like this.
  7. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    Yep i feel that too, i'm going to try gt car during maintenance (if it works).
    What is more assuring is that iracing is very active in physics tweaks compared to rfactor 2.
    Looking at history it takes S397 extremely long time to fix the stuff.
    Like engine inertia issue (not able to do burnout or car dying on full throttle clutch release) is almost 2 years old !
     
  8. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    I don't know what is the cause and what is the consequence but one thing is clear to me, it is that at over 200°C one should not be able to sustain the same lateral force on the tire as at 80 to 100°C, and yet :

    upload_2021-1-28_9-36-38.png

    The concern now is that there is no official data on the grip of these tires at high temperatures, all we have at our disposal is what we see in the different races and the testimonies of the different experts who are all unanimous on the subject: beyond a certain temperature, the tire degrades faster and loses a lot of its frictional capacity .

    The question is now to know what is called "high temperature" (it seems to me that more than 200°C must be part of it, quite clearly) and "loss of friction capacity" ...

    More than 200°C? Don't worry, we're gripping to death buddy, focus on the trajectory...
     
    Pawel44, Nieubermesch and mantasisg like this.
  9. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    iRacing's player base is larger, it pays for a service and doesn't hesitate to make its dissatisfaction known on social networks.

    iRacing has no choice but to correct quickly, they offer a paid service after all, not rF2.

    But yes, it's bound to go faster, especially lately, they feel the hot breath of ACC and rF2 currently in their neck ...and this is also the reason why it is important to fix rF2's flaws if any (I think it is quite obvious there are some).
     
    Pawel44 likes this.
  10. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    so far what i believe and what i read is that there are 3 places they need to check

    1. Tire relations to temperature
    2.drop off after peak Slip angles
    3.Static friction vs sliding friction
     
  11. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173

    I'm not sure how to find static vs sliding friction but so far the graph showing Friction Coef. vs Slip Angle doesn't seem too odd (maybe a bit too high friction coef but could be related to track actually, not official track so can't say) :

    upload_2021-1-28_11-19-57.png

    That being said, there is no friction coef drop when slip angle is very high, I don't know if it is normal but we already spotted that.
     
    Last edited: Jan 28, 2021
  12. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,157
    Likes Received:
    2,981
    Oh man,that steering is something else for sure. The technique he does is not the same to our subject, I think so because he does not apply understeer and roll with it, he is wildly sawing the wheel going into understeer and out of it in milliseconds in search of optimum angles, just as you have noticed. Noticeably large steering ratio makes that supper apparent. Also his steering looks like if it could be pretty light, just guessing that he might have ran low caster, which with large steerign ratio would indeed make steering lightish. Surely it would be awesome to get data, get to talk driver, to engineers, mechanics, or even drive ourselves. Still it does not make videos non valuable.

    Interesting findings that does indeed not seem alright, too bad we don't have an access to physics files, there is very curve that controls heat influence for friction, although tire abrasion also influences that, and abrasion is also depending on heat.

    What confuses me is that your findings of what should be the slip curve doesn't show to be as much wrong.

    I am thinking about slip curves now. Thinking about heat. Thinking about duration of the slip. I wonder what are the scientific standards to plot slip curve. In my mind the duration the tire is kept on extreme angle must be important factor. Because of heat. To put it simple, I suppose it is logical that real life slip curve wouldn't drop extremely at extreme angles for the moment. But tire at extreme angle will start generating lots of heat, therefore it should be logical that during the time same amount of extreme slip should keep on decreasing tire friction. Especially if heat would not only decrease friction coefficient, but also would cause tire rubber to shear off greatly.

    Thats just an assumption and a guess, but if in case there really is this wild insensitivity of heat, and also if by some chance the tire abrasion vs heat curve is flattened as well, then it is very logical reason why certain rF2 cars has to be driven the way they are in order to achieve best pace. Also tire wear fits there too, although tire give up also is influenced a lot by thermal degradation.
     
  13. Pawel44

    Pawel44 Registered

    Joined:
    Oct 1, 2020
    Messages:
    34
    Likes Received:
    21
    I know what you mean, but I was blaming ACC in the past under Aris videos and comparing it to rF2. ;) I want both games to be as realistic as possible and some obvious flaws to be fixed. I would prefer rF2 over ACC, because it's another level of driving when we count dozens of possibilities (GT3, GTE, F1 etc. etc.).
     
    Last edited: Jan 28, 2021
  14. Flaux

    Flaux Registered

    Joined:
    Oct 5, 2010
    Messages:
    948
    Likes Received:
    380
    See, that is a bit of how misleading videos can be when you don't have the right information to understand whats happening. I talked to a driver who did some races around 2000. He drove the old 993 GT2 rs turbo and then the first 996 gt3r (that evolved to the rsr later) and he said it was super strange because the 996 was the first to have powersteering and therefore it was quite light and you couldn't feel a lot. And now you know why Wolf is sawing the wheel and does so still today. He learned to drive without powersteering and lost one of his key senses and this was his way of coping with it. Had nothing to do with caster...

    But I'm with you. I love to watch onboards myself and base some ideas on the stuff that I see from time to time. :)
     
    mantasisg likes this.
  15. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,157
    Likes Received:
    2,981
    @Flaux Of course, thats why I was aware that its just a guess, had powersteering in mind as well. But I think I wasn't wrong about that he doesn't actually plow the car with understeer, but keeps on sawing in search of optimum. You seemed to say the same. That thing can be confidently claimed as it can simply be seen to be happening. Going for the reasons is a bit slippery slope, as you have pointed out as even what the driver was previously used to has an effect. So IMO whats happening is pretty clear, but reasons why it is happening is tricky.
     
    Flaux likes this.
  16. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    This approach is indeed interesting, in fact any approach allowing to highlight inconsistencies seems to me to be a good idea.

    Could you tell us which simulation you used for this test and the details of the functions used (in order to reproduce them as faithfully as possible)?

    I have time (and more importantly, the desire) to test on other simulations as well and if there are indeed other elements that can be brought in, it will always be welcome.

    For ACC it will be more delicate since the telemetry is very limited.
     
  17. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,157
    Likes Received:
    2,981
    If this would be what consumer market aimed simulation developers would try to make, then I would gladly buy DLC with these modern racecars and drive them a lot, participate in racing. But simacing has made me to believe that they are soulless and boring, they looks a lot more exciting IRL. But I understand that I am not like 1000 other sirmacers, whose wallets has an ultimate vote over what the reality is.

    Two choices guys like me has:
    1. Shut up and just let others enjoy.
    2. Raise fair questions, and have fair discussions whether things happening are truly realistic enough to be considered as realistic.
    One thing we, those who are thinkers, must understand. Doesn't matter if couple of us will educate ourselves to be able to pick up evidences from real life and use logic to evaluate realism to accuracy level that is plainly judgable just by observation. Doesn't matter if we will be able to further increase accuracy and reliability of our judgement by acquiring hard data... There will still be hundred times more simracers who are there just to have fun without thinking, and they are the ones who run simacign related businesses. Financially we are not so important. Even those who has established name in the simracing comunity - still doesn't matter if there are too few. Even if it happens to be some certain big tire manufacturer such as Michelin, it still doesn't really matter.

    Finally, what I want to say is - just don't stop to think guys. It doesn't mean necessarily criticising, it goes for about defending too when we believe something is truth. Developers aren't motivated to make things unrealistic or realistic, they are motivated to get things done that will be perceived to be realistic and enjoyable for most. There is tiny tiny chance that knowledge about vehicle physics could spread wider than it otherwise would if no one would put effort to think and talk about it and also put effort in getting data. In my mind realism of simulation in consumer market will always be very much directly influenced by how well people are able to understand basics on what makes cars do what they does. Unfortunately it is not encouraged, it is not encouraged to look at the reality, it is wrongly accepted that realism is impossible by exploiting various misconseptions and in this way negating underlying physics potential of fulfilling fairly decent level of realism.
     
    Slip_Angel and Nieubermesch like this.
  18. Comante

    Comante Registered

    Joined:
    Nov 20, 2013
    Messages:
    1,396
    Likes Received:
    908
    I won't be so drastic and dramatic. More simply, updating the engine is no cakewalk, we have seen how much disruption the UI has been able to generate.... and UI should be a marginal part of the code (it is not in this case), go figure the cascade effect that updating the physics engine can have, and I'm not talking about bugs or unexpected things, everything would probably need to be retuned to take into account the updates.... "everything" mean all the content that run under this engine.
    Now, it seem a huge task, and it seem aimed to hit a bunch of drivers more than to improve the simulation.. improve in a fringe situation where lack of solid data make expected behaviour, causes and consequences debatable (46 thread pages). I think that transmission, aquaplaning and other more broadly needed effects can have priority over this. And I can't tag with bad faith the developers to have other priority that can impact 99% of users, instead of risking destroying everything to take care of the 1%.
    Simulation is a polyline that try to follow a spline, there will always be offsets, better take care of the bigger gaps first.
     
    RaceNut and Nieubermesch like this.
  19. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,157
    Likes Received:
    2,981
    It is not about an engine, it is about how the cars are built. While engine is improtant too, the way how cars are built is more important subject. Engine would be more of an issue if something was impossible, plainly not working, or wpi;d have to be achieved in incorrect ways.

    I like to completely forget the UI lol, it did take away lots of believing in developability of rF2 :/ I dream a lot about improved transmission, they did somethign like it for AMS right ? There are several other things left to desire, but I honestly have no idea what to expect. But this is off topic. It is not totally critical for the subject of how cars are made to handle.
     
  20. mechanic

    mechanic Registered

    Joined:
    Nov 7, 2019
    Messages:
    11
    Likes Received:
    12
    I think the physics engine is pretty good, as long as it is fed with correct data. Tires are not 100% correct it seems, not sure if this has something to do with data, as it is pretty complex.

    Would be nice to focus on the drivetrain dynamics indeed.

    @mantasisg I guess there is a third option: the modding community, yourself included. I bought rf2 for the modding option and I hope that the correlation with reality is good enough to test setups of actual real life racecars. If this is possible we can make great mods ourselfs in race them in niche leagues for people who prefer maximum reality and are not really that talented in racing (me).
     

Share This Page