Car stats/params in rF2 is weird at best

Discussion in 'General Discussion' started by williang83, Sep 12, 2020.

  1. williang83

    williang83 Registered

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    First of all professional and commercial wise simulation software means to simulate real world behavior and exposure data in order to analyze them.

    This simulator offers no stats whatsoever, so you have no official (by official i want to know what they are actually using in the car and not on paper) data about track width, wheelbase, empty weight, tire ranges, brake ranges, engine stats, etc. It is not even possible to hide behind license excuses because not even simple stats like widths are officially said. For example the C7R wheelbase on all specs i saw online should be 2708mm instead it appears to be 2850mm according to dampPlugin.

    It does not compute and/or expose static data like static weight and others. I mean very simple but still important data that should be quite simple for a simulation to expose them. I would be impressed if the simulator does not compute those to use them in their physics.

    If i try to extrapolate information from what it is possible to come up with dampluging i realize that there is really something off. The corvette C7R for example that should weight around 1245kg, according to many specs in the web, by either using the susp force channel or damper pos * spring rate, it turns out that the total sprung mass is about 1693kgf, +400kg off of sprung mass? I understand the BOP but +400 kg off is quite a lot. Besides at this point with that huge amount of weight increase i ask myself if the tires has been adjusted to compensate it, otherwise you might end up with tires overloaded, more than real life, decreasing even more the coefficient of friction (supposing that tire simulation here is realistic beyond initial impressions). This would explain why the car likes to easily lift oversteer at lemans, specially if you raise the rear, even slightly.

    I mean i have played a lot with setting up both in iR and rF and the former when it comes to data is definitely more reliable to an extend.

    This is definitely not a rant post, quite the opposite. However i must say that, okay, the driving feeling that rF2 offers, it goes beyond others games but gosh it disappoint me a lot because of this pseudo simulation selling key point which does not meet what i see in the platform (eg. environment impact on car balance).
     
  2. Lazza

    Lazza Registered

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    Wheelbase isn't reported to plugins, so DAMPlugin just throws 2850mm in there as a ballpark figure so the built-in oversteer calculation and graph shows something. (you might notice it's always that value, regardless of the car)

    Of course the game knows them, but they aren't exposed to the user. These are different things.

    How are you calculating the total sprung mass from the reported susp forces? I haven't checked a log with that car, so I'm curious. I suspect motion ratio may come into things here, but it's late so I could be wrong.

    Anyway, the rest of that paragraph is predicated on what could be (and likely is, given the effects on all aspects of car behaviour a ~30% increase in mass would have) an incorrect interpretation of the data you have, so I think it's better to ignore. You rarely post about rF2 in a positive manner and this smells of confirmation bias.
     
  3. williang83

    williang83 Registered

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    Which is exactly what i thought. The point is that there is no official thus reliable source anywhere of any stats no matter how simple they are

    I was being rethorical, of course the platform compute them. Now not exposing them is extremely naive, not something that you would expect from a simulator.

    I didn't go very fancy or something. Simply reading susp kgf load on static condition and not below 5km/h where the simulation is artificially computing numbers due to singularity issues of any vehicle model, actually of any simulator being car, aircraft....commercial, professional or military and i know this very well. Well i had a thought about motion ratio but still it should not matter because MR dictates the amount of displacement and not the force itself. So 1000 lbs of force on a given spring translate its displacement in inch to a similar or different displacement of the wheel, leading to a specific wheel rate. The force is still the same but the displacement amount can be different in both axis, but i'm sure you already know this.

    Lol with this behavior you are taking this too personal. I'm extremely unbiased, i do not worship anything in life. I see what works and what do not works, whether or not i'm mistaken. This conversation is me trying to understand what is going on, something that seems to be off, on which might be a wrong take by me. Racing games wise, rF2 is the product which i play most, specially lately. Now i would never stop myself from pointing any downsides just because i'm using a platform or even enjoying it. So i really don't see any connection on your personal take about me not worshiping rF2 and blindly ignoring any lacking stuff. All platforms has their pro and cons, a lot lacking features/completeness, some more some less, and i will highlight them all without exception.
     
  4. dazzer

    dazzer Registered

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    In some cases the exact physics even fails in the worst way, I have seen it in Assetto corsa, Iracing, RF2, Race Room ...
    It is obvious that the developers will look for a way to bring a balance, the physics will not always be 100% exact to the indicated specifications, not even in real life the cars use the same specifications ...
    Apart from that to do the BOP, the cars must yield in the physics and settings.
    And everything else he wrote is just a lot of text.
    hqdefault.jpg

    My advice is: relax, think that no matter how hard we try to simulate real physics, there is still a long way to go to be exact. and finally, be happy. c:
     
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  5. williang83

    williang83 Registered

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    Which is the reason why i still play them even if i have the opportunity to drop in real track from time to time. As i said rF2 is the one who i enjoy most despite its flaws.
     
    Last edited: Sep 12, 2020
  6. williang83

    williang83 Registered

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    Anyway i'm starting to better understand how rF2 translate setup page into car setup, which is a bit different from what i would experience in iR.

    For example ride height in iR means setting up the static extension which means soften your springs translate into unavoidable making your car drop height, just like in real life. rF2 is different, you really set the car static height which is completely strange. Soften springs does not make your static height drop, it stays the same which means the platform automatically increase the extension for you to keep your car in the same static height. This behavior is very strange, and i would expect to have more control on the components rather than simplified and automatic adjustment. It is a crucial different approach that must be taken into consideration but i believe that this method is way less logical and unpredictable.
     
  7. Emery

    Emery Registered

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    Meh. Either way is valid. Due to the suspension motion, most chassis setup people will automatically reset static ride height to the same as before spring change when installing softer springs because they're following "only change one parameter at a time". iRacing is basically saying to the user "you have to remember to set the correct ride height" rather than automatically doing it for them.
     
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  8. dazzer

    dazzer Registered

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    In that you are right, the system to configure the cars is different, in RF2 the setting mode is more automatic.
     
  9. Kevin van Dooren

    Kevin van Dooren Member

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    This logic sounds fishy. Suspension forces are not simply equal to wheel forces. If the displacement of the wheel is different compared to the suspension displacement, then the force must also be different. Otherwise you are creating energy.
     
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  10. mantasisg

    mantasisg Registered

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    If I understand correctly. Basically less force is needed to do same job if it is being distributed in larger displacement. It is just basic principle of leverage. I suppose thats because to do work it takes either more power to do it all, or less power but distribute it more. You know... "give me beam long enough and I'll lift the moon" stuff.
     
    Last edited: Sep 12, 2020
  11. williang83

    williang83 Registered

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    I don't deny that there is something fishy, not specifically for this reason, which is why i'm trying to figure this out,.
     
  12. williang83

    williang83 Registered

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    Yeah springs works by conserving energy and then eventually release them. However load transfer happens no matter what, just like ARB that does not reduce the transfer load at all, you are still going to transfer the same amount of force regardless of your ARB setting. What you are doing with ARB is reducing the roll and taking some load transfer from one axle and adding to the other axle. Same happens for longitudinal forces, you cannot avoid them from being transferred however you can adjust how fast that will be, how much it will lower/raise the end and how much room you will leave to tires in order to be able to deal with bumpiness, but the transfer is still there.

    Motion ratio dictates the displacement, the wheel rate in other words, but the force is still there, you cannot do a heck about it otherwise the simple equation Load Transfer = Weight * G Force * CoG / Wheelbase would not be that simple.
     
  13. Kevin van Dooren

    Kevin van Dooren Member

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    Like mantas already mentioned somewhat in his post, the suspension arm is like a lever, so forces do change.
     
  14. williang83

    williang83 Registered

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    Definitely
     
  15. Lazza

    Lazza Registered

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    I don't think you understand what people are telling you.

    If the wheel moves vertically 100mm, but the spring+damper contracts 50mm because of its angle, the force at the tyre and the force on the spring will be very different. It's pretty much exactly analogous to having a load at the end of a lever and a supporting spring halfway along it - the spring only moves half as much, and needs to take double the final load.

    Code:
      .______________________________________@
                        ^
    pivot             spring               load
    
    The spring force will therefore register higher than the actual load. Physics hasn't broken.

    I would suggest the thing you've overlooked here is what "suspension force" means in the game.

    The reason I got a little personal earlier is I think you very quickly went from seeing something that didn't make sense to you, to deciding something was wrong with rF2's figures. You basically accepted the car is 30% heavier, then talked about whether the tyres have been made to compensate for that, and then the fact they probably haven't explains some behaviour you've noticed. (reinforcing your initial assumption about the weight)

    This is taking an idea and running with it; instead you could say "Ok, I'm not getting the result I'm expecting here. Assuming the game is using correct figures, I must be doing something wrong - let me check my working."

    If the car were really 30% heavier, the tyres would need to produce much more than realistic grip to get correct cornering speeds (as I'm sure you know, rF2 uses a physical model so unless the tyres are noticeably bigger than real life, this would mean using very grippy rubber in the .tgm), a much more powerful engine to compensate for the extra mass you need to accelerate at realistic rates, much more powerful brakes to slow that mass. Spring rates, damper rates, ARB rates, would all need boosting. The tyre structure itself would need large changes as you've proposed.

    Does all this seem the most likely to you? Bearing in mind also, this is a game that supports modding and has a multitude of official and third party mods (effectively open source, including some of those official ones especially in the early days - there was even a whole blog on the BT44 development) that are based on real figures and getting realistic performance - suggesting there isn't a need to use massively incorrect values to overcome some sort of shortcoming a 400kg weight increase would presumably be attempting to do.

    This is a driving game. It's not a tool for physically analysing the car you're driving. I don't know why you think the game is failing if it doesn't expose all data to users.

    If you're developing a car for the game you're obviously working in the opposite direction - you start with all the data, implement it, and the game lets people drive it. It still doesn't need to expose any of your data in order to let them do that. You're criticising the game for not doing something it's not intended to do (or be).

    You are overthinking this. Movement rates around zero can indeed be problematic, and I'm sure the game physics deals with this internally (there are some clues in ptool, which itself is enlightening in terms of what the game simulates), but you don't need to somehow fake the loads just because the car isn't moving. You're making assumptions without basis. You obviously know more than the average user but you're applying your knowledge in the wrong way here.
     
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  16. williang83

    williang83 Registered

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    I agree that my approach has been impolite at best, specially considering that attacking rF2 was not the goal of this post, i'm total on fault on that. Believe it or not, rf2 is my favorite platform with no contest, actually i've played iR for a couple of weeks like 3 months ago after 4 years away of it.

    That being said, just saying there is a change is not a discussion per se, it provides no addition. I guess nobody denies that leverage does change force on the other end, well after flat earthers i'm not surprised of any denier. Beside I was on the phone hence my reply was so simple.

    I'm trying to quantify this change due the nature of my personality. I'm starting to believe that with the data available at the status quo this information is impossible to be extrapolated with reliable precision. I've been reading Milliken to see if it can be extracted somehow but nothing so far. However with your inputs about mod and others, i'll just accept the validity of the model and be open to the fact that i don't have enough data to come to proper conclusion whatever it is.

    For last but not least, it is still ludicrous that very simple but crucial data is not exposed.
     
  17. Lazza

    Lazza Registered

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    I hear you there, I've also been mostly posting on my phone and it doesn't help to allow best communication - something that can already suffer on a forum. My long post was at a keyboard though... I'm not that patient :p

    When large amounts of the telemetry data is blocked it's easy to misunderstand what the remaining channels are. You've been around quite a while and I expected you to know the difference between tyre load and suspension force and therefore didn't explain the distinction.
     
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  18. williang83

    williang83 Registered

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    Same for me, long post only from computer hahaha

    Anyway the difference between susp force and load is quite obvious. I was trying to come up with some conclusion without enough information, i was aware of it but i still went for it...yikes
     

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