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Why Is LFS So Much Better Than Anything Else?
(326 posts, started )
Good stuff!
phew lots of info interesting bit about the combined slip modeling and im a bit surprised that anybody would actually use the constant long force approach
mind to go on a bit about why the lat force is depending on the long force in sub limit situations ?

and about your experiment ... first of all "My car gets forty rods to the hogshead, and that's the way I likes it!"
and i have to agree with bob you have a whole bunch of understeer in your arb and spring setup
to really make a comparison you should try a car that represents an xfg with a throttle oversteer setup a bit more

Quote from jtw62074 :FFB has kind of ruined some of the other sims for me in comparison, quite frankly

youre turning into a true lfs fanboy
Good that we keep Todd in that closet so we can get clear and informative posts about tire issues

But he just did spoil all the fun from my car building (realised how impossible it is to get proper handling) so now I need to get some other platform where to work I guess and there seem to be only LFS and Todd's sim, but both impossible

Maybe I just wait then undetermined time, that has worked before too
Quote from Bob Smith :I don't think it's just due to the diff IMO (in LFS), it's the whole combination of the setup. Judging from your description, that's quite an understeery setup.

Understeer gradient at the limit was about 3 deg/g, which is about the same as the most oversteery production sports cars.
Whoops, I stand corrected. Turns out this is a bit more towards oversteer than most production cars, but by racing standards it is indeed quite understeery, especially in comparison to some of what you guys like to run
Very nice. Is Racing Legends done yet?
Quote from Shotglass :youre turning into a true lfs fanboy

That's because he's very brilliant! :hide:
What's this understeer gradient you've mentioned? Does this come from raw slip angles? I'm just curious if it's anything I can add to my analyser, but I'm ignoring slip angles completely atm (from a simplicity point of view).
Quote from jtw62074 :When it's done properly, the lateral force will drop with increasing traction regardless of the slip angle. Even when you're way under the limit. As you approach the limit it winds up very smoothly transitioning into limit behavior. As such, you can steer with the throttle quite nicely. It's all very predictable and drifting actually becomes quite a lot easier. Suddenly you find yourself steering as much or more with the throttle than the steering wheel, even when you're below the traction limit. I've yet to see that anywhere except in Gregor Veble's model for Racing Legends and my own.

Do you claim that all current good simulators have such a basic flaw? It's very hard to believe.
Quote from w126 :Do you claim that all current good simulators have such a basic flaw? It's very hard to believe.

I don't, clearly that issue is with almost any sim, I think LFS is somewhere between other sims and perfectly done model, only one that I have played that seems to have lot of basics right, I'm hoping that these small issues will be addressed in future and what I have read they are going to be addressed indeed.
Wtf, that F1 car is like a rally car, seems like the car is turning around a pivot point in the center and has unbelievable slip angles. Why o why did i thought LFS was so true to life.
The problem with tyre models seems to be that there isn't a lot of correct info available. Car 'dynamics' is all pretty straightforward, Suspensions are tricky but its all forces, angles, distances..

Tyres? Most you can find is very 'basic' info on this, plus of course many of the publicly available grip vs slip curves that show lots of grip drop off. It is quite understandable that a guy making a sim physics engine will use these dubious models and data as a base.

It seems like most of the time they are copied to sims, because programmers assume the data is correct and the models accurate. In fact it just seems to be a case where books have basically copied eachother from lack of good sources instead of really delving deeply into the matter.
I'm sure pro companies like Bosch or Siemens etc have long since developed way better and complex models but they probably like to keep that to themselves, plus for 'sim use' you need a 'simple and effective' model. Industry models tend to be overcomplex, like a ~60 parameter Pacejka model, where you basically can (and will at least a few times go badly wrong with the input unless you have the $ to actually properly test the tyres.

So I would say it is anything BUT hard to believe that most of today's racing sims have considerable flaws in them, especially when it comes to tyres. Its just a 'grey area' as far as freely available data goes.

The extend of the error is subjective. I would say any sim that can have even a hint of POWERoversteer produced by a front wheel drive 'normal' car (i.e. with tyres at the back and some weight on them) is not a small flaw. Its quite fundamental tyre behaviour.

This is where it becomes subjective. Todd said he reckoned the last LFS physics patch (quite a while a go that was) to be a huge improvement. I would say it was a small step in the right direction; I was and am still left with the general impression that some fairly fundamental things are not good enough yet. I do think that of the currently available sims, LFS does the best job, but the room for improvement is huge.

Scawen does seem aware of the shortcommings, hopefully to the extend that somewhere before S3 final we'll have a much better tyre model. That is also good compared to the ISI competition where the developers just don't really seem to care what reality is.

Currently though, I'd say all sims go wrong somewhere pretty fundamentally when held to the 'realism light'.
Quote from Whitmore :Horses for courses.

GPL is the best 60s open wheeler sim
NR2003 is the best NASCAR sim
Rally Trophy is the best 60s/70s rally sim
RBR is the best modern rally sim
GTL is the best historic GT and touring car sim
GTR2 is the best modern GT sim
rFactor is the best mod platform
LFS is the best fictional multi-class sim

and I would think NetKar Pro will be the best hillclimbing sim

Quote from frankwer :Wtf, that F1 car is like a rally car, seems like the car is turning around a pivot point in the center and has unbelievable slip angles. Why o why did i thought LFS was so true to life.

The low speed behavior of the F1 car is tricky to model with the current physics. Very low weight, with limited mechanical grip make it behave inaccurately in situations. Better to have limitations in a true realtime physics model than to have completely predetermined outcomes for set speed/turn angle situations.

Put 10 other types of cars into an F1 sim and i doubt you'll get the solid experience across the board that LFS delivers. Is it perfect, not by a long shot. Is it the best all-round online racing sim out there, I would say undoubtably.
Quote from Niels Heusinkveld :...

the bit i dont get about this is ... what the hell happened to info sharing within the scientific community ? there should be an abundance of papers on tyres and tyre models readily available via google but there just arent
Quote from srdsprinter :Better to have limitations in a true realtime physics model than to have completely predetermined outcomes for set speed/turn angle situations.

Papy, ISI, RBR, NKPro etc all have true realtime physics models
ISI does not.
Even the ones that do are not designed to handle the many forms of racing that LFS does.
Kind of makes you wonder doesn't it

The ones that say they do, but only target one type of car on one surface.... I wonder how "universal" they really could be, since we can't drive a variety of vehicle types.
I'm not sure what some people want? But I am sure no matter how hard I search, that I'm not going to find a PERFECT racing sim, and people whinge about this and that, well if you believe you can do it better, by all means, go ahead I just go and actually drive IRL if I want realism, but as far as sims go LFS is leading the way imo
Quote from Ball Bearing Turbo :ISI does not.

Of course it does ISI physics has its flaws just as all sim physics does, and there is no harm in saying you prefer sim Xs physics over sim Ys but its sad there is so much mis-information. ISI physics modelled suspension links and dynamic camber changes years before LFS for example.
Quote from Whitmore :Of course it does ISI physics has its flaws just as all sim physics does, and there is no harm in saying you prefer sim Xs physics over sim Ys but its sad there is so much mis-information. ISI physics modelled suspension links and dynamic camber changes years before LFS for example.

Yes, but only because they have been around from times of SCGT and when you compare F1 2001 and rFactor there is quite little improvement actually over all those years, they have 10 people team working and they development speed seem to be still slower than for example what it is in LFS.
I'm almost suspecting that guy who had made physics engine originally is no more in ISI and they can't make big changes, but surely that must be just my imagination

But also they do have realtime force simulation running indeed, hopefully there would be lot of improvements done in next version of engine so it would actually be capable of handling something else than ~1000kg cars well and they really should make their own tires that actually work like tires, that would create some interesting competition to markets
Quote from The General Lee :But when makes is that extra bit special?

Gameplay. LFS has a great gameplay.
Games that last long are games with a great gameplay such as Counter Strike, Unreal Tournament (the first one), Wolfenstein Enemy Territory, Falcon 4, Grand Prix Legends...
Quote from srdsprinter :Better to have limitations in a true realtime physics model than to have completely predetermined outcomes for set speed/turn angle situations.

Not necessarily because a formula is just as predetermined.
Take the function f(x) = 3x^2
No matter how many times you find f(5), it will always return the same value, but say you have something along the lines of:
f(x) = e^3x + cos x/3pi + ln (x^2) + ... + 3tanh 10x etc.
Your CPU is going to go insane if you tell it to do that 500 times a second among other things. so just compile a table of values, load it into RAM and voila! Suddenly it runs fine and it's not much less accurate either if the steps between your values aren't big. The reason why ISI's engine is rubbish is because most of the things thrown in there aren't real quantities and on top of that, the things that are are rubbish data anyway. (Yes, I can say this for a fact, no, I can't show you how I know this stuff or what it's meant to be)

On the other hand, if you go and do a CFD model (stuff that runs no-where near real time) for aerodynamics and chuck all the data from that into tables of values and then use that in real time from your sim, you'd get some really good results.

Why Is LFS So Much Better Than Anything Else?
(326 posts, started )
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