Quote from Viper93 :

I have talked to an SCCA driver that runs in their Pro series and he says that his Trans-am would just "snap" after too much loading and his RX8 would gradually lose traction. So maybe both could be

Solid axle cars. Leaf springs....

Quote from AndroidXP :

The question is, how do you actually measure such curves in real life? Who knows if all books saying the curve looks like *this* are actually correct? All that mathematics and theoretical calculations are nice, but who knows if they really match reality?

Well, Axus was going to try to push a tire manually to measure things....





You have a point here!

Quote from Vain :

In LFS it can takes well over half a second of (constant) countersteer until the rear has retaken grip. A quick stab into the correct steering angle isn't enough, you have to leave the steering wheel at the right position for a while until grip is regained.
Is that the same for real high-speed slides? My only referance are cockpit-videos where it doesn't look like that, but that's hardly an evidence.
(A problem might be that in order to regain grip quickest, I often load the diff with some percent gas, so I can utilize the LSD while regaining grip. This might hinder regaining grip, while still being better than trying to do the same with an unloaded (and thus open) diff.)

I could understand better a lower powered car snapping back even under throttle. But a car with any reasonable output... I don't know, under throttle you're just using more "traction budget" which shouldn't be condusive to this behaviour. And the open diff is a great point too that should make a big difference, since the vast majority of street cars have open diffs.

Quote from Ball Bearing Turbo :

I could understand better a lower powered car snapping back even under throttle. But a car with any reasonable output... I don't know, under throttle you're just using more "traction budget" which shouldn't be condusive to this behaviour. And the open diff is a great point too that should make a big difference, since the vast majority of street cars have open diffs.

I don't either... maybe if we could get Michelin on the phone :Handshake

Maybe you could drive the SRT4 Backwards since it has a locking (sort of) diff and let us know how it behaves

Quote from AndroidXP :

Well, give me a low profile tyre and a high profile tyre (both on a RWD car) and I'll compare it

just use the fzr and the fo8 for a rough comparison

Quote from Ball Bearing Turbo :

Maybe you could drive the SRT4 Backwards since it has a locking (sort of) diff and let us know how it behaves

I'll try that =P it does have locking, works pretty good for the most part( still get slight wheel spin under very heavy cornering, IE rear end sliding type of cornering) but as a whole it works great.

Here is a thought.... The tire curve changed after we got the F1 car. Any of you thought that BWM supplied tire data and telemitry to the devs along with car?

With Michelin licensed tyres, I'd imagine they got some cool stuff.

Blowtus, I'm pretty sure I've heard a lot of reviews comparing street and track motorcycle tires say some were good for certain parts of a racetrack while others, other parts of it.
I'm pretty sure I've heard similar comments on Michelin vs Dunlop vs Bridgestone in MotoGP.. Are all differences of racecar tires within and between brands really negligible?
Would it really not be analogous to real life to have each LFS tire brand with their different (overall equitable of course) performances to choose from?

I wasn't suggesting it wouldn't be worthwhile at some point, but I don't think it's useful to equate any current physics difficults as some sort of specific tyre trait. As far as being worthwhile 'at some point'... I really do think it's a minor issue, and also suspect data on the scale of differences between same profile / purpose tyres could be very hard to come by.

I see, thanks.

See also : http://www.lfsforum.net/showthread.php?t=7840

For another problem. Spinning wheels and I think still locked wheels have some problems. Hope this is fixed too soon

Quote from Woz :

I think there is far more "snap" at the edge of traction now. Remember that 90% of the snap you feel IRL you feel through your body. Watch replays and you will see the cars snap.

Well the devs should make it so you get that sensation in the game. Getting physics 100% right by the numbers on a PC won't bring about the same fun-factor as making it feel as real as in real life.

it's a simulation - you're playing the wrong game if you think effects are going to be canned for your benefit.

I don't agree with Woz though. There isn't a car or setup in LFS that breaks / gains traction nearly as angrily as plenty of cars out there, imho. I'd put more substance in the 'it's just because you can't feel it' theory if I hadn't also driven a couple of cars that break and gain traction as smoothly as LFS...

what woz said is part of a thing called truth. to reach it, u need a bit of empirical knowledge.

now lemme reach for some more vdk, the peppers show rocked.

so... which bit of empirical knowledge would that be?

RBR is touted for it's quality physics, it has a heap more bite on tarmac. I'm no RBR fanboy, this is just an example of a quality game that clearly has a different view.

Quote from Blowtus :

so... which bit of empirical knowledge would that be?

The part that's really empirical and can't be communicated via sentence, even if by wild chance you dunno the meaning of words, which btw, rarely helps in forums. Quite common though, so i guess a group dynamic is about to begin.

Quote from Dethred :

Well the devs should make it so you get that sensation in the game. Getting physics 100% right by the numbers on a PC won't bring about the same fun-factor as making it feel as real as in real life.

So you are asking for the physics to be bodged to get this feeling. If they do they you will not be able to fully work out what is going on with the car.

Realistic reaction to situations is the ONLY thing that is right. The fact you feel loads of things through your body is just a shortfall you have to make up for with your mind because unless you have a motion platform there is NO WAY to simulate this. Its the same as people asking for engine vibration to be sent through the wheel, its just canned and hence wrong. If you want the bodge effects you might like rFactor and ISI based sims.

When I drive in LFS I try to picture the circle of friction for each tire. I also keep track of how I imagine the weight is distributed over the wheels as both of these are things you need to keep the car in balance. These are things I cant feel through my body as per real life so I have to make up for this shortfall in my mind.

Also I use 100% FF in CP and between 80-120% FF in LFS for my DFP. This gives me a far greater picture of the car as well. It means at times I have to fight with the wheel but most of the time I work with the forces so the FF does not feel too powerful.

The fact that the U physics are far more solid makes this far easier than it has been before to keep the car on the edge. There is also a huge snap effect and its now very easy to snap spin the car 180deg if you do not keep the car in balance once the rears let go.

The reason that people say its too easy compared to real life to keep the car drifting is because IRL you have FEAR to deal with. Never underestimate the effect fear has on your judgement. IRL once the rears step your body feels the massive shifts in G and you need to work out how and where and how to best balance the car before you are off and slam into something.

That said if you do want to feel real fear in LFS you could always attach electrodes to you nuts and use outsim to trigger a 2000V shock when you crash. I bet you drifting on a track like South City will not be as simple then lol

Quote from Blowtus :

so... which bit of empirical knowledge would that be?

RBR is touted for it's quality physics, it has a heap more bite on tarmac. I'm no RBR fanboy, this is just an example of a quality game that clearly has a different view.

RBR is a great sim but even the devs of RBR say that the physics on tarmac are off. Its good on gravel though.

which car are you snap spinning 180 degrees?? I can't remember the last time I had a self induced spin... I haven't been driving the bf1 though.

nice one woz

Quote from KiDCoDEa :

The part that's really empirical and can't be communicated via sentence, even if by wild chance you dunno the meaning of words, which btw, rarely helps in forums. Quite common though, so i guess a group dynamic is about to begin.

lol! the fact that it's observation based doesn't mean you can't talk about what you're observing!

Function: adjective
1 : originating in or based on observation or experience <empirical data>
2 : relying on experience or observation alone often without due regard for system and theory
3 : capable of being verified or disproved by observation or experiment <empirical laws>
4 : of or relating to empiricism

Quote from AndroidXP :

The question is, how do you actually measure such curves in real life? Who knows if all books saying the curve looks like *this* are actually correct? All that mathematics and theoretical calculations are nice, but who knows if they really match reality?

Real curves are measured on a variety of machines such as these:

http://www.ocp.tudelft.nl/tt/vehicle/testing/trailer.htm
http://www.carsafety.com/tire.htm

The tire's load and camber is controlled (as well as possible anyway, there's usually a bit of noise) while the slip angle is swept back and forth throughout the whole range while the forces are recorded. Many machines do slip ratio too (traction/braking) which is how you can get the full friction circle type of plots.

Doug Milliken's company web site discusses the procedure they use at Calspan for tire testing, along with a mention of the cost. It ain't cheap, unfortunately.

http://www.millikenresearch.com/fsaettc.html

For Virtual RC Racing 4.0 we've had a machine just like this built (except MUCH smaller) that measures forces in the same manner. However, in our case with the little foam tires it's all much, much cheaper to do.

The force curves shown in this thread for LFS look quite realistic. What needs to be remembered is that you can take two tires of the exact same width and dimensions from the same manufacturer, but of different "families," and the curves can vary remarkably due to the inner construction of the tire. The number of plies, how the cords are wound, the cord angles, thickness and shape of the rubber in the sidewalls, and so on have an enormous impact on the shape of those curves.

Essentially tire designers can make the curves look pretty much however they want, so as long as you get curves that look vaguely like what you see in this thread for the LFS tires then you're quite realistic in that regard. Since the tires in LFS are fictitious (correct me if they aren't) then it's a bit odd or perhaps a little pointless to say whether they match a real tire or not. They probably do match up very closely with some and not so closely with others. If I had to say yes or no to "are the tires realistic in regards to the shape of the lateral force vs. slip angle curves" I'd say "yes" though. There are tires that look pretty much just like that. Is the load sensitivity "right?" I couldn't say for sure, but I imagine it's quite well within the ballpark to give the model a big thumbs up in that regard.

One thing to throw into the discussion here is that you can have two tires that peak at the same friction coefficient and slip angle, but have different shapes up until that point which has a profound impact on how the car feels (I've spend a lot of time playing with that in my sim). The LFS force curves shown in this thread rise at a nearly constant slope until you're at around 80-90% of peak grip, then they roll off into the peak very quickly. That will feel very different from a curve that rises more steeply in the beginning and starts rolling off (decreasing the slope) earlier. The latter will feel more forgiving and be easier to drive (which will make a lot of people scream "arcade" even though that's very common for real tires. "Realistic" does not automatically mean "hard." It did when you went from Pole Position to Indy 500:The Simulation or GPL, but most racing games have been past that point for many years now...)

That latter tire will also feel as though it does not regain grip as suddenly as the first tire does. That's a driver perception thing though. In reality the tires aren't "losing grip" at all in the first place, so there's nothing to regain, but that may only make sense when you're looking at the curves when thinking about what the car is actually doing. If the curve rises quite linearly and rolls off suddenly into the peak (like in LFS) it will feel like the car breaks away more easily and "regains grip" faster on recovery than it would if the curves rolled off more gradually. But again, tires can be made to have force curves that look however you want, so the ones you have in LFS are perfectly realistic in that aspect

The location of the peak itself has an even bigger impact on how the car feels. I.e., if it peaks at 15 degrees the car will feel more squishy and forgiving. I've run my sim with peaks at or past 20 degrees and it's quite fun, a lot like GPL where you go fastest through the turns with big drift angles (which was totally wrong for '69 F1 cars, but a whole lot of fun). As you start increasing cornering stiffness so you peak at 5 or 10 degrees, the car usually gets harder to control, even if you increase the overall grip at the same time. It's more touchy and hard to find the edge. When I run 3 or 4 degree peaks in my sim, I don't really spin out often at all, but instead end up sliding, then over correcting and spinning back the other direction rather violently. It feels like the car has "regained grip" extremely suddenly with peaks at low slip angles. So much so that it's hard to catch a slide without overcorrecting.

One other thing to point out is that you can take two identical tires from the same manufacturing plant and the curves can vary considerably. I saw a study on this once and was quite shocked at the difference. In the end, the manufacturers are just working with rubber and wire essentially rather than anything rigidly formed, so there's quite a lot of variance from one tire to the next, even if they're supposedly identical. My PC with the scanner is down at the moment so I can't show the graphs from those tests to you guys, unfortunately.

nice post Todd