Quote from libben :

Well, I really dont care for laser tracks and real cars, though they are a nice extra. But the physics, etc etc. The future and all that.

Is this sim better then LFS? What good is a sim if it is the best in simulation but you got a better over all package in another sim like iracing.

LFS is like, hook up online and do some races and so on. If you go to iracing, don't you do more leagues and so on? I get the feeling that this is more incorporated then LFS.

The tire model is (at the moment) some degree better than LFS. Of course, they have many more tools at their disposal to develop that, so it would be odd if that wasn't the case.

Since that's the most 'important' part of a racing sim, it does make iR feel more accurate and engaging than LFS. The tire model combined with the scanned tracks are what give the sim it's feel, and that part is second to none by a fairly large degree.

That being said, there is currently less being simulated in iRacing overall than in LFS. This is seen in the drivetrain mostly where there is no stalling, clutch heat and whatnot.

It certainly isn't as flexible, although for testing / practice purposes you can run any car on any track as long as you license it.

I did think that the laser scanning was just a gimmick until I tried, clearly it isn't. Give one of the free trials a spin and make your own conclusion about it though by all means.

Quote from codehound :

I drove GPL for the past eleven years but made the mistake of trying iRacing. The iRacing tire model has that little something that lets you know how hard the car is working to hang on to the track. At some point you can sense that the tires are really being given all they can take and you had better be careful. Whether you are at 50%, 100%, or over the limit at 110% iRacing has a different feel for each case rather than just gliding over the track surface at different rates of speed with the same feel. The latter is the way GPL now feels to me. I would put the present LFS tire model about half way between the two. I really hope that LFS has tried iRacing and notice what I am referring to.

I am not sure what causes this. I have written a tire analysis program that attempts to calculate the loads and the shape of the tire sidewalls in order to get a better feel for what happens to a tire under stress. The program seems to give reasonable results for vertical load as far as spring rate and contact patch size but the lateral load case is flexing too much. Even so, there seems to be a cross coupling effect between vertical load and side load. A side load reduces the vertical spring rate of the tires and increased vertical load increases the side deflection. So if you apply a side load to a tire the wheel will tend to settle closer to the track surface. If the tire loses side grip then the side deformation will decrease and the tire will try to push the wheel up causing a sudden increase in vertical load as the tire tries to jack the car back up where it would normally be for less side load. With added vertical force it would seem that the tire would momentarily regain grip and the process would then repeat itself. This may be the source of that little chirp-chirp sound you get as you reach the limit as apposed to the constant squeal sound that occurs below the limit.

If anyone (Bob Smith ?) knows of a good source of information for sidewall behavior would you please post it. I can find loads of stuff on contact patch stuff but that is mainly about grip. The sidewalls are what really count for spring rate and feel. At least that is my opinion.

This is an excellent post, thanks for doing it.

I 100% agree with your observations in your first paragraph as well.

You sit on a throne of lies BOB!!!

(or at least beer...)

Shotglass is HAWT

...Because harder categorically means more realistic right?

:rolleyes:

Someone try it with Bob's roadgoing setup, since most roadgoing cars don't use racing setups.

I think you misread; I'm not the person(s) having problems with it...

Edit: Ah ok sorry

Last edited by Ball Bearing Turbo, Mon 31 Aug 2009, 15:07.

Quote from DragonCommando :

I've tried it actualy, and it didn't seem to make much difference.

If it's only me that has this problem I'll be going for a loop

Just to be clear I'm not saying that there isn't a problem at all with the longitudinal tire grip... Just that it never seemed to affect me in such a way as you're describing, I rarely had an issue doing a proper brake stand. Mostly in the XRT and the GTR version of the car.

I always used a manual clutch as well of course.

Quote from DragonCommando :

It's always bothered me that I can't do a brake stand

Well it should bother you because I've done them for years in LFS through all sorts of patches. I generally did them on the starting grid before the clutch heating was modelled (since if you're not aggressive about it now you can wreck your clutch rather fast). Got quite the number of comments about it too. I rarely had a false start as a result; so something you're doing is causing the movement, must be in the setup somehow.

Obviously it's not done well with mid or rear engined cars.

My rears were always green right off the bat.

Quote from Bob Smith :

....blah mutter chirp... the first news update this year...

Rampant speculation time.



yes I know that's pulling out of context and probably means nothing but at least it's more interesting than 80% of this thread.

Quote from Shotglass :

very nice

can you give some more info on how the old model worked (conceptually; no code details obviously) and how the new one is different to give us physics geeks something to fill the time with between now and when the new version goes public?

Indeed. Curious minds need food!

You type 448 characters per minute
You have 78 correct words and
you have 3 wrong words

Quote from AndRand :

But it doesnt imply all the cars would need to be changed. Opposite to setups.

If they change the tire physics the handling of all cars will inherantly change - which is what you already said so I'm getting confused as to what you're trying to say...

Quote :

Doesnt locking rear wheels evenly on brake means that inner, faster wheel brakes harder therefore turning rear even more?

I'm afraid you've lost me again... Bottom line is that the wheels need to be able to turn at different speeds. If they can't (locked diff), the car will resist rotation hence a tendancy toward understeer all other things being equal.

Not so hard to beleive. It just means that there's things in the tire model (which is universal in LFS) that make all cars prone to more understeer than is perhaps realistic. Thus the changes they're making to better the VW will affect every single car's handling.

Quote from AndRand :

I can't see why locked diff off-throttle would make car understeer?

What car turns in easier one with an open diff or a locked one?

Last edited by Ball Bearing Turbo, Fri 14 Aug 2009, 19:24.

Quote from (The Stig) :

Lets point out a few pointers here

1. You are demo user
2. You dont know weither Demo Cars are the same as GTR's

So really I havent even tried out Iracing so you know better than me or though if you want to post a improvement doit in the Improvement section mate that might help you abit.

If it's a (tire) physics issue it doesn't matter much what type of car it is. The fact that he's a demo user is completely irrelevant, as is the fact that he hasn't tried the GTR cars. He also wasn't posting a suggestion, but rather had a question which is perfectly valid in General.

edit: this was @ dumbass0

It's probably somewhat logical to presume that once that's fixed that there will be more "lift of oversteer" for a given setup.

Last edited by Ball Bearing Turbo, Fri 14 Aug 2009, 18:58.

Quote :

Lift throttle oversteer is a rear wheel drive thing, related to engine braking. I know the Formula BMW is rear wheel drive, but the wings are usually set to be understeery at high speed, so the FBMW may only show lift throttle oversteer at slower speed. Are either of the other 2 demo cars rear wheel drive?

It's not just a RWD thing although that could obviously make it worse, it's a weight transfer thing.

Quote from dumbass0 :

I swear to god I read on this forum that Scawen had to rewrite something in the engine to make the Scirocco handle correctly (and if I recall properly it was the UNDERsteer that was the issue).

Fixed

Quote from ScoobRX :

Most of the setups I've made with lift off oversteer have full blown oversteer, that is if you just turn while coasting the car will spin regardless of whether or not weight was transferred forward. So it's simply oversteer not lift oversteer. And as I've already mentioned, even cars that understeer can lose rear traction if you suddenly let off the throttle so I'm convinced some aspect of the physics isn't the way it should be.

Well, AndRand and GF already pretty much summed this up. You're looking at this from a very simplistic standpoint. I don't think that there's anything wrong with LFSs physics that would tune out "lift off oversteer" to a noticable degree, it's all about weight transfer and that's pretty hard to shit up math wise to be honest. If there was anything in terms of physics modelling to blame for it; the (front) tires simply would not have enough grip or there could be load sensitivity issues in the tire model somewhere. However iR's "point there go there" (as you put it) feel at lower speeds is probably for the same reason (if there is one in terms of inate physics difference) that you think it simulates "lift of oversteer" better.

Quote from Hallen :

In my opinion, and this is just my opinion, iRacing goes a bit far with throttle steer. A lot of those cars would be down right scary to drive if they really behaved like that. I don't know if that is because they don't have fully modeled diffs yet, or if they have a flaw in the physics, but that's my impression. I am probably wrong about that, but the point is, iRacing cars exhibit a whole lot of throttle steer so coming to something like LFS, it can seem like throttle steer isn't modeled.

I notice it too, but I find that I can be much more deliberate about it in iR and it's much more sensitive to it. I still think LFS goofy setups may have a lot to do with that (by that I mean the anomalous setups aliens use to go fast in LFS). Your BMW also has a relatively low power:weight ratio in comparison to something like the skip. I found driving the legends on road tracks to be the epitome of throttle steering goodness, which seems very much in line with NikiMere's experience in the car. If you dig up the video he posted of him driving one in a race, you get the impression that it feels very much like the iR version and it looks damn fun

Just some thoughts.

Quote from Neilser :

Hmm, you sound like you mean it affects downforce (since you mention setup and track familiarity) but I meant tyre cooling. If wind affects tyre cooling wouldn't you prove that by just leaving the car stationary on a windy day and see how long it takes for tyres to cool?
I'm sure wind must affect the handling somehow (or why have it?) but I've actually never tried high wind

I know you meant cooling. I suggested the open wheeler because there is more exposure to ambient air, and the velocity thereof is not shielded by a wheel well. I suggested the setup/track familiarity because if you are real comfortable with it you'll notice that your heating/cooling cycles are noticably modified by a high wind setting.

With less rubber why wouldn't it get lighter?

I bet it's so marginal that you'd never notice it though.

Quote :

This point has come up already in this thread, but it's not clear if people are sure about it being absent. Anyone know for sure if this effect is modelled in LFS?

It's definitely there. More noticeable in open wheelers. If you really want to test it, take one out with a setup & on a trak you're very familiar with & crank the wind to full speed.

sa habla no espaniol

Good stuff Bernd!

Long live T7R!

Being a gamer has nothing to do with that really, this is all about how much you want to / or are comfortable shelling out for a hobby. I went with the i7 primarily for gaming and I'm rather glad I did

Quote from Bose321 :

Sorry, you turned it arround, CCC is alot easier. And I don't care about psysx or whatever, And I think ATi logo and name are better. Plus, we have a hot girl.

You know, both control panels are pretty.... self explanatory. I have no idea how anyone could get confused by either one really.

PhysX is a major performance booster in applications that use it - it's definitely not useless. Emulating it on your CPU is a bit pointless since the whole idea is that the GPU can do it an order of magnitude faster (literally in most cases).

And what are these AA and AF "fine tunings"?

Kinda got me on the hot girl part, but using sex to sell video card packaging seems like grasping at straws out of desperation