Hi there.
There was a big discussion going on about general tyre physics :

http://www.lfsforum.net/showthread.php?t=8619

But I wanted to ask especially about the acceleration thing.

I think LFS is quite perfect to a slip ratio of about 0.8 or so.

So there seems to be a drop of force between the perfect point somewhere between a slipratio of 0.1 to 0.2 and the slipratio between 0.3 to 0.8. But the difference is quite low as it is in real life. Finding the perfect spot at 0.1 to 0.2 is very very difficult and doesn't result in MUCH better acceleration.

So far correct.

BUT I think the problem is with high slip ratios. The force should drop much further at slip ratios of 1.0 to 8.0.


Example :
This seems to be kind of a real tyre with a late peak at about 0.3.

http://www.performancesimulations.com/files/longslip.JPG

Now look at the difference there from 0.2/0.3 to 0.8. Tyre loses about 10% force from slip ratio 0.2 to 0.8 or lets say 1.0 to make it easy.

Slip ratio is defined as wheelSpinVelocity/groundVelocity-1. So that means if tyre goes twice as fast as car it has a slip ratio of 1.0 (100% spin you could say)

Now lets take a start with the XF GTI. Reving up at the limiter, which is about 50 to 60 kph. Lets say 50 kph at limiter.
Then get off the clutch. You'll notice, that there is no blue clutch sign left. So clutch is fully engaged.

Tyres are now spinning at 50 kph, while car starts from 0. Lets say car is now at the beginning moving with 5 kph.

That means, tyres are spinning 10 times as fast as car is moving. This means 10/1-1 = 9.0

Now watch the graph. It seems that it will decent even faster. But lets say it is linear. This means the loss of force is about 9 times as big as from 0.2 to 1.0.
This would mean only 10% force left, which is a bit off, because the curve eventually stops at some point to drop force even further.
But something like 60% force left or so seem to be quite realistic ...

In LFS its more like this examination :
http://www.lfsforum.net/attach ... id=11060&d=1149423472

Of cource these are R2 and street tyres are a bit different. But I think it is the same there. Force doesn't drop anymore between a SR of 0.8 or 9.0.

Changing this would have a great effect on races and general realism. I admit it is hard to find the perfect spot. But people just going full throttle at the start would be significantly worse than people trying to get a good start ...

What about that in next full patch (V)? Shouldn't be really hard to implement, just changing this drop off at high slip ratios ... but in my oppinion it would improve LFS a lot. Racing experience and realism. And it would improve Acceleration lesson in Training a lot

Perhabs also changing this automatic start signal to a free start. But I don't want to ask for to much

Greetings
RIP

EDIT : I meant data instead of date in the title.

EDIT2: These are the tyre data of formula1 2002 : http://www.racer.nl/images/pac_f12002.jpg
And I think they had some real source ... goes down to about 70% to SR 2.0 and then staying about there ...

Last edited by RIP2004, Thu, 22 Jun 2006 23:03.

Really great to see that everyone here is discussing properly I also gave up point 3 of my list (FZ50s strange slide behaviour because of weight transfer) because it really was just a setup thing with the differentials.

I fully agree that reaction time is a big factor for good starts. And it is something completly missing in LFS.

But wheelspin is another noticable factor.
Some quotes from real life racing drivers I found in the internet :

___________________________________________________________
"Stefan Everts (Yamaha L&M Motocross Team) DNF-first
“I had a bad start in the first race with a lot of wheelspin, to start on concrete is hard if you are not used to it!"

________________________________________________________

David Coulthard: I moved a little bit just before the start and had to stop the car. And then that's when the lights changed so I then got too much wheelspin. And to be honest I thought I was going to be swamped at the start, but I presume Mika must have made a bad start as well
___________________________________________________________
“I got a very bad start with too much wheelspin but I still overtook two or three cars at the first corner." (Formula Audi, Deman)
_____________________________________________________________

Now to roadcars:

Drag Racing:

"Oh and for the people saying that the drag skills are good launches, smooth gear changes and no wheelspin, isn't that really a skill for all motorsport, a bad start can **** any race."
____________________________________________________________
"Get a good launch to start with, too much wheelspin & apart from killing your tyres, you'll not go far. Also, don't burn your clutch sitting on the line, it'll affect your gearchanges later up the strip and if it's slipping you aren't getting drive to the ground.

Keep driving tyres about 5-10psi lower than normal, depending on conditions (remember you have to be able to brake effectively after the finish line :blink: )

(Seat Ibiza car ... so no racing car)

...
_____________________________________________________________
______________________________________________________________

You can propably find much more on the internet about that. But bad starts are nearly ALWAYS mentioned in connection with wheelspin. In race cars and in street cars. Tips for 1/4 mile races are always to avoid to much wheelspin. The only point where it is wished is when heating up your tyres at the beginning.
Also see my M3 vs RS4 video. It is obvious how much the M3 gets backwards at the start in the end because of wheelspin. And that even though the driver immediately goes off the throttle and corrects that mistake and doesn't stay full throttle. And both react pretty good to the signal.

@Ball Bearing Turbo :

I don't understand of what evidence you talk? As I said above there is really no single "evidence" for anything here ... just contrary information. I showed a video from the real world and there are some graphs which are quite different.

But just lets take some "evidence" of the other side :

http://www.performancesimulations.com/files/longslip.JPG

This graph posted by jtw (Todd?).

Now look at the difference there from 0.2/0.3 to 0.8. Tyre loses about 10% force from slip ratio 0.2 to 0.8 or lets say 1.0 to make it easy.

Slip ratio is defined as wheelSpinVelocity/groundVelocity-1. So that means if tyre goes twice as fast as car it has a slip ratio of 1.0 (100% spin you could say)

Now lets take a start with the XF GTI. Reving up at the limiter, which is about 50 to 60 kph. Lets say 50 kph at limiter.
Then get off the clutch. You'll notice, that there is no blue clutch sign left. So clutch is fully engaged.

Tyres are now spinning at 50 kph, while car starts from 0. Lets say car is now at the beginning moving with 5 kph.

That means, tyres are spinning 10 times as fast as car is moving. This means 10/1-1 = 9.0

Now watch the graph. It seems that it will decent even faster. But lets say it is linear. This means the loss of force is about 9 times as big as from 0.2 to 1.0.
This would mean only 10% force left, which is a bit off. But 60% force left or so seem to be quite realistic with your "own" evidence.

But I'd say those graphs say nothing. Every one is different. No real knowledge in there. I'd go for real experiences and ask drag people or watch my video ...
There is a very significant difference with street tyres. And it should be easy to start faster than someone going full throttle as IRL too ...

btw. everyone can post just some graphs from the internet. Watch this one :

http://www.racer.nl/images/pac_f12002.jpg

See how much force drops even to SR 2.0?
Empirical data. You all have to believe me now.

No no. I do that kind of things all day, because I study at a technical university. And I know how to prove something with real evidence. You need SERIOUS sources which back up each other and have to explain and understand it all. Not just posting some graphs, which show infact different things and pick up the one, which you like most.
In a LFS forum most people tend to take the graphs which show how infinite great LFS is and how perfect physics are already. No more changes ... its all great

Generally we may agree that LFS is one of the best simulations out there right now. But it still has flaws. And not just one.

@jwt : Plz don't misunderstand me. I think we can talk very productive and I know you have a lot of knowledge. But some people seem to be to much impressed by just some graphs which can be interpreted this or that way, because you don't know if the tyres are from a space shuttle landing, a formula 1 car or a old beetle road car.

Last edited by RIP2004, Sat, 10 Jun 2006 22:16.

@Ball Bearing Turbo :

I didn't see many really serious information, which must be completly right.
Where are many different graphs from different sources speaking of street tyres and not "some" kind of tyre and confirming each other?

There is no information confirming that these are usual street tyres.
There is no information about mad spinning wheels. I just saw it to 0.x
As someone stated we are talking of a slip ratio of a lot more than 1 or am I wrong?
There aren't different serious sources for that information. Could be some curve someone painted by hand.

And then there are lots of informations from videos, interviews with racing drivers, personal experiences ... and I think seeing a car beeing significantly faster is much more convincing than just seeing a graph drop a bit.

IRL there is a huge difference between a good starter and a bad starter. See Walter Röhrl in a usual 911 against some TV reporter in a 911 S with more horsepower on dry tarmac.
Walter Röhrl wins very very convincing with less power.

Then put me against lets say a WR holder in LFS in a drag race with the same setup and same car. I bet you won't see a significant difference from the start. Perhabs after the first 2 gear changes. Why? Because something is wrong there. I don't know if the tyre curves are responsible for that, but I don't know what else could be the problem?
Not finding this point? Well NOONE is really finding that point. You can do a hundred starts and the only difference is <0.1 seconds, while in real life there are whole car lengths differences between street cars?

Watch for example this and don't tell me these are slicks :

http://www.autoblog.com/2006/0 ... eo-audi-rs4-vs-bmw-m3-cs/

Ok it is slightly, but really only slightly greasy. I'll get a better video if I find one.
Look the first start (2.08) in the drag race between M3 and RS4 and how close the M3 is at the beginning.
Then take a look at the start at the real race in the end (9:48). Watch this huge difference and the presenter and race driver shouting "aaah... wheelspin and Tiff's away".

I'll look for better examples of street cars in the real world ...

Quote from Blowtus :

that was why I suggested a clutch pack with high coast lock - much more stability when you lift off.
But now we're sliding off topic...

Hey ... offtopic but it really works pretty well

Tested it and now FZ50 really drives acceptable for a real road car. The rest of difference is propably down to some small details and the lag of an ESP system ...

No it just feels strange to me I think it's also a question of taste, as it is never near to real feedback IRL.

In a real car you feel a lot more. And it's just strange to have just one very very small component of it (the wheel) and even this component feels fake in comparision to the real thing.
And I think it helps, if you know the reactions of the car just because of your experience without feeling them through the FF

Well FF in LFS is quite a huge difference to FF in real races. In real races I would prefer resistance. But then in real cars even the way I sit is different than in front of a PC. There are forces pushing you left and right in corners and a very very easy going wheel would be really dangerous.

I just talked about LFS and my experience there. I found FF more disturbing in long races than helpfull.

Ah here the correct quote of Walter Röhrl :

"Wenn ich das schon höre: Das muss man im Hintern spüren.... So ein Schmarrn, wenn du was im Hintern spürst ist's nämlich vorbei, denn dann bist du schon längst runter von der Straße."

@blowtus : Yeah, I played a lot with the differentials. That's why I noticed it really.
If I use an open diff its quite drivable in terms of throttle in a corner. But then you'll really notice how slide-happy the FZ50 is just by getting your foot off the throttle in nearly every situation I couldn't fix that with a setup.

Quote from jtw62074 :

I don't use FF either very often, even though I've got the red Momo. I just use the self centering most of the time. I can feel what the car is doing purely visually and often forget in our physics discussions that a lot of (most?) people are using FF, which has the potential of confusing what's happening.

In any sim, not just LFS, the FF quality can really change the impression of what's happening. You could have a perfect tire and physics model and all that, but if the FF isn't up to par or done properly or lags or anything like that, people will think the physics model is somehow wrong because the car doesn't feel right. So you'd get the FF guys saying the sim stinks while the non-FF guys that go purely visually and/or with sound cues saying it feels very much like the real thing.

RC racers frequently talk about how the car "feels" even though they have no FF at all and are of course not sitting in the car. They're 50 feet away on top of a driver's stand but can feel when the car gets loose or is pushing and so on, and will come in to make tiny setup changes to improve the handling. Purely visual and of course absolutely realistic since, well, it's real

Funny that a lot of main critics and observers of physics aren't using FF

@viper : I know what you are saying. But I think some kind of traction control or even ESP, which is slower but easier to control, would be a better solution than using very strange tyres ...

@jtw :

Interessting data there. I didn't find a lot of data on that subject. I don't know how much % grip is lost with full throttle.
See Blowtus perhabs. How is slip ratio calculated? In the XF GTI tyres are spinning with about 60 kph, while car starts moving from 0. So at the peak point there is a difference of 50kph to 60kph between tyres and car.
What slip ratio is that?

I just know for sure, that the difference IRL is more than a car length and very noticable, even if driver starts to correct it and doesn't stay fully on the throttle. With road cars. In race cars it should be even more noticable. Watch Touring cars or formula 1 partly ...

Not only in car shows or races on TV, but also in my car it is noticable. In the dry ...
But I did it only once, because it gets pretty expensive IRL to spin the wheels really hard. But also trying to start good at a signal you'll notice that it gets worse if there is spin.
I think the 6 or 8% perfect slip aren't really far from the point where you don't notice slip at all in the car. Tyres always slip to some degree to move the car.
I don't know if it is perfect, but in RL I try to get as less feelable wheel spin as possible to be fast off the line.

But what is your oppinion on the results of the current LFS physics? Do you really think less than 0.1 seconds on 40m between full throttle all the time and a try of a controlled start is realistic? That should be about 1m difference.

________________________

Perhabs two other points of LFS physics that seem wrong to me.

Firstly the stopping way of locked wheels. I should test it again in Patch U, but I think it is still the same. Fully locked wheels stop really well in LFS, which is very strange.
It is very hard to stop better with controlled braking.

Secondly, and it isn't perhabs a real physics problem ... the FZ50.
Something in the simulation of that car is strange. I am really no expert on this, but I think it really overreacts on weight transfers. It starts to slide very very easily.
It is correct that old porsches (rear engine) were very dangerous on braking. But the FZ50 is a bit off. Perhabs something about the static parts of suspension which can't be tweaked in setup? Something that isn't simulated correctly yet?
Current porsches drive way easier. But I would say, that even old porsches aren't sliding that much ...

Well what matters is that you don't really need a lot of feedback to judge how hard your tyres are spinning. Just watch the revs and how they change in comparison to your car speed.
If revs stay at the same place near the limiter, while car changes speed, its obvious they are spinning a lot. If revs move up like the speed of your car there is not much spinning ...

Additional you will hear the sound and you will see the tyres depending on your view.

GT4 is different and much more easy to drive. There isn't the same challenge of driving and they had to do it because of the limitation of a console and pad steering for most people.
But it's not really bad as simulation of real cars based on data. They collected a LOT data of real cars and real tracks and I bet that their tyre behaviour itself regarding grip in some way isn't really worse than the one of LFS. At least if you choose the correct type of tyre and not drive the premium semi-slicks which are mounted as standard on road cars ...

As some of you know I am someone who criticizes weak points of LFS physics often. See physics thread at the moment for example.

I play a lot of sims and I have more than 1 wheel. But my main wheel is Microsoft Sidewinder Force Feedback.

BUT I always play LFS and all the other sims without force feedback. I tried it and I don't like it:

- it is highly artificial in comparison if you drive real cars at the limit sometimes. The force feedback just from the wheel in a real car is far superior to the artificial PC force feedback of any simulation

- it's harder work for long races. I think it could lead to mistakes in an 1 hour game

- your reaction times are faster without it ... see above

- and like Walther Röhrl, a famous german driver, said. If you feel it with your "popometer" or in this case through the FF, it is already to late. You did already a mistake and it costs time. You have to THINK and KNOW what will happen, if you want to be a real good driver.
So FF helps the weak in some way It makes it easier to correct mistakes and avoiding to spin out.

_____________________________

FF helps in some way. But where is the connection with physics itself? Why not judging reactions of the car itself? FF is another chapter ...

Walther Röhrl : "Das Popometer reagiert viel zu spät, was passiert muß schon vorher klar sein."

Last edited by RIP2004, Fri, 9 Jun 2006 21:51.

Ok, perhabs Tiff Needle was wrong there But its still slower then ...

EDIT : It's Tiff Needell ... sorry

@jtw : It should! see answer to "askoff"

@viper : Live for Speed isn't meant as easy to drive arcade game. It is meant as simulation as close to reality as possible.

You won't find a single tyre in the whole world mounted on a street car or usual race car, which doesn't drop off at acceleration if spinned massivly. Perhabs there are some special tyres for drag racing, which isn't really a race series LFS really aims for.

For people which have difficulties with controlled starts, there could be a traction control for every car in the game.

@Woz

That's perfectly right. I always criticize the lag of feedback and I bet you won't even find a feedback like IRL for the next 10 years.

But as I said it is possible to feel that difference in Gran Turismo 4 or all the ISI games without really more feedback than LFS.
GT4 even has got less feedback ...

You can control it just by looking at the revs. I don't say that you will find the perfect point exactly always. But you should be able to find a much better point than full throttle all the time

@askoff :

There are many ways to look at it.

1. Physics ... its no question that a tyre with a small difference between tarmac and tyre rotation will be able to transfer more force. Rubber needs some difference. No question about that. But to much difference is definitly counterproductive ...

2. Races on TV. As said above nobody pulls of with full throttle. If it would be possible to design tyres like in LFS they would have done that in formula 1 and there would be no need for a launch control or careful starting.
Ever seen any kind of race on TV? There are always much more differences than in a start in LFS between experienced people.

3. 1/4 mile events IRL. Ask them. Watch them. No one will pull off with full throttle, because hard spinning wheels are bad.

4. Ask a real racing driver. Watch for example "Fifth gear". In the race between BMW M3 and Audi RS4 they did a drag race and described the difficulty. Jason Plato and Tiff Needle talked about it.
In the BMW M3 you can't go full throttle, because the tyres will spin. And thats bad!
In the Audi RS4 traction is no real problem, but you can't go full throttle also, because the clutch starts to slip then.

And in the real race Jason Plato in the M3 had to much throttle. He shouted angrily "baaah, wheelspin." and you could really see a huge difference. BMW M3 started pretty bad in comparison to the runs before that ...

5. Try it for real. I did it in my car. My tyres will be changed next week and I just wanted to test out how full throttle would be. More to see just one time, if the tyres smoke. And they do
But you'll also notice that it is very slow with much wheel spin. At least in car with enough power (mine has 150 bhp on FWD)

Its cheaper to test it on a wet road, although it is slightly different. You will move very very very slow with full throttle

EDIT : btw. "GOOOOOOOOOOOOOOOOOOOOOOOOOOOAAAAAAAAAAAAAAAAAL!"

Last edited by RIP2004, Fri, 9 Jun 2006 16:09.

Agree. It's another good method but it will propably show the same. Acceleration doesn't drop significantly with massivly spinning wheels.

Quote from Woz :

RIP2004: Do you really believe it would be possible to spin out the tires on a car like the FO8 IRL when doing a standing start and not have to correct the steering?

No. And that isn't the point. But I thought corrections would cost some 0,0x seconds in the straight forward direction and therefore manipulate the comparison between brutally spinning wheels and more sort of controlled start.

@viper : See Blowtus. I don't know of any tyre that starts great if throttle is just floored. Watch quarter mile events. Except of some AWD cars with very very good clutches (which don't slip much) no one is just going full throttle at the limiter and get the foot of the clutch. All raise the revs to some point where there is a good torque value and the revs can't drop to much in low revs. And then when foot is off the clutch they balance the throttle and not just floor it.

And this should be the way it is in LFS too. I don't think that it is much harder to find the point in LFS than in RL. It is also possible to find the point slightly before locking the wheels in LFS and even locking single wheels. And if physics were correct you would immediately notice if tyres start to spin much, because you would accelerate less.
It's possible to find that Point in GTR and in rFactor. In fact it is possible to find that point in every ISI Sim, in GPL and even in a playstation 2 game called Gran Turismo 4. At least finding a point where acceleration is better than just flooring the throttle.

So I really hope for a tyre update. This "bug" is now here for ages since the beginning of LFS and the lesson "GTI-acceleration" in training is just ridiculous because of that problem. Every keyboarddriver and/or Need for Speed Underground driver will be rated best in that lesson, although the describing text is correct ...

Most important thing about it : starts are very very boring in LFS in comparison to nearly every other racing game including NFS. It's one half of the problem. The other half is the arcade style starting procedure with a signal blocking your car controlls ...

@android : Ok it may be this small good point before wheels that spin to much. So could be. Main thing is the area beyond that ...

Another thing are locked wheels and their braking way. Didn't test it since Patch U but I am pretty sure it is still a problem. They are far to short with fully locked wheels ... did you test that?

Last edited by RIP2004, Thu, 8 Jun 2006 13:27.

@bob : I didn't disagree with the fact that it is easy to start it without spinning. But without steering input it is unstable ...

@ball bearing turbo :
Why is it counterproductive? It is important! Every steering input costs some time. And if we are talking about 0.07 seconds in 40 meters this makes a real difference.
This steering could exactly match these 0.07 seconds loss if going full throttle.

It is important to minimize such things. If testing acceleration over more than 1 gear it is also important to use automatic, because different shifting points, even if it are just 100 rpm, do make a difference.

@android :

Even if these about 0.07 seconds difference are a result of tyre physics and less grip with spinning wheels and not because you corrected the steering a little in order to keep the F08 stable they are far to less.

If you could possible do a 0.07 seconds better start in real life against going full throttle I bet most people would do full throttle in real life too. It may be easier to find the point IRL but as you see in real races there are a lot of differences at the start in race cars without automatic traction control.

The difference between different drivers are far more than 0.07 seconds, eventhough nobody goes full throttle and everyone tries to get a good start. There are a lot of grades between a perfect start and a bad start.
A lot of different fast drivers at start. It's not only good and bad start. It is good start, not as good but good, medium, slow, very slow and as bad as going full throttle. So this better point of throttle than full throttle must be very wide IRL. Otherwise lot of people wouldn't try to find it if they highly risk to go slower than with full throttle.

I think the problem of LFS isn't the grip at the good point. It is the grip beyond slightly spinning wheels. Grip should get less and less. It makes a difference if tyres are spinning like 20% or like 90+% with full throttle. Car shouldn't move much with madly spinning wheels. But in LFS mad spinning wheels are equal to slightly to much spinning wheels, which is very good to accelerate.

IRL even a start with very shortly spinning wheels and then no spinning should be faster than a mad full throttle start without any back moving of the pedal.

Last edited by RIP2004, Wed, 7 Jun 2006 23:44.

Quote from Slidaaaa :

Why sadly? at least when u buy a ps3 there will be something much less sucky than nfs to play in it.

glad to know

I also don't know what is meant by sadly.

The Gran Turismo series does a really great job in simulating real existing cars on real existing tracks. If you choose the correct tyres (the worst ones for old cars and the second worst ones for usual road cars) times on "Nordschleife" for example are very near to real times with that cars.

Driving with the race tyres would be like using very very soft formula 1 tyres, which don't get worse after a few kilometers ... and sport tyres are more like very good semi-slicks.

In fact it does a better job in simulating the general behaviour of the real well known cars and in learning the tracks than LFS. Simply because LFS hasn't got many real cars or real tracks (forget Runabout ... who knows the real runabout and times on real well known tracks?)

After driving "Nürburgring Nordschleife" on GT you can learn a bit about the track. Its not like the real thing but you can really learn a lot before driving for real first time on it.

Whats worse in GT than in LFS is the challenge of driving itself. It is very simple and fun oriented. Steering with pad is a lot simpler of course. But the simulation of different cars and their performance against each other is really good. I am looking forward to GT5.

In GT you also have to drive a good line to be fast. You also have to control throttle to a certain amount and each kind of car behaves like you would expect it to. FWD cars understeer, RWD oversteer ...

(There is even a difference between a good start and a full throttle start with road cars in GT , which isn't simulated correctly in LFS :razz

I generally notice that a lot of people in the LFS community are a bit harsh and hostile against other games. There is also no other community which starts regulary a new thread to just say how great the developers are. Again and again and rated 5 stars again and again. Who cares

People who like other games often like LFS also and drive it. The other way around people often talk bad about other games. There are always people who bash games, that are not their favorite game. But I think in the LFS community there are more of them. Especially avoiding every game with the ISI engine and writing how bad it is without having driven it :P Just my impression ...

Last edited by RIP2004, Wed, 7 Jun 2006 19:06.

@Bob Smith :

I meant F08. It isn't stable with full throttle start. You have to make corrections with your steering which cost time. At least if you are looking at very small differences in time ...

http://rapidshare.de/files/22468812/F08.wmv.html

No steering axis assigned ... so no things that could manipulate the result.

And TC was a bad term. I meant controlling throttle manually. If you push the throttle less, it isn't starting to spin and you don't have to correct => costs less time and is faster on a straight.

@Vain : If you change the gear ratios perhabs :

http://rapidshare.de/files/22469186/BF1.wmv.html

___________________________________

You'll really notice the problem if taking the GT cars. IRL there are huge differences between different drivers at the start. And no single one is just pulling away with full throttle.
In LFS it is completly different. Nearly everyone is just pushing the pedal to the metal. And it is kind of a perfect start. Even if less throttle would make a difference of 0,0001 seconds. IRL the difference is HUGE. Huge enough to overtake without a different setup or slipstream ... just by getting a better start.

Quote from Vykos69 :

well, even in the F08 the NONE full throttle start is significantly faster than the full throttle spinning wheels start.

So the physics is on a good way already. it might not be perfect, but in some of the fast cars it is already better to start with a decent pedal work.

But that's just because full throttle start spins the F08 after a few seconds. At least at my tests. So even if it just begins to spin that costs time. With TC it doesn't spin or begin to ...

Waiting for next tyre update.

Quote from AndroidXP :

I think the difference is far too small to warrant not going pedal-to-the-metal in cars where the stability isn't an issue to begin with.

In LFS but not in real life.

Quote from AndroidXP :

I guess because it's extremely hard to ride on that limit. All the time spent feathering the throttle costs you probably more than simply letting the tyres spin. Testing with the BF1, a TC start at 8% slip was considerably faster than a burnout start. But yes, maybe the grip should be even less when the tyres spin like mad, instead of staying exactly the same at anything > 12% slip. Who knows

I think this kind of start : http://rapidshare.de/files/20129298/FTwithoutTC.wmv.html

should be significantly slower than this kind of start :

http://rapidshare.de/files/20129603/manualstart.wmv.html

Even if it isn't spot on perhabs. But it should be much closer ...

I didn't manage to start BF1 without TC. It spins after a few moments full throttle ... perhabs a setup thing? Can you show me two starts of BF1? I'd like to see TC being faster than full throttle ... completly same setup except TC, automatic shifting and no steering axis assigned ...

But I think it is the thing you mentioned last. Spinning wheels should get much less grip if spinning even faster than that.

Slip ratio 0,2 ; 0,3 ; 0,4 ... its all the same and near enough to perfection. It should get lower and lower. In LFS slip ratio 1,0 would still be fast I think

Quote from AndroidXP :

Very nice posts, Todd! Thanks

In the meanwhile, I made some accelleration tests, comparing longitudinal grip to slip ratio. The following graph was done with the FZR's R2 tyres at 120kPa pressure with a live camber at around 0°.

From the graph we can see, that the "missing" falloff curve from the slip angle tests is indeed there when accellerating/braking, and this also shows us that a spinning wheel accelleration is NOT as fast as a just-on-the-limit one. In the attached example the optimal slip ratio was at about 6-8% (if I interpret that value shown in the graph correctly).
A part of the most extreme forces closing in to 2g were caused by the short normal load peak you get on accelleration, but the most values were in the 4900-5000N range and the curve doesn't look all that different (actually almost no difference) when limiting the data to this range.

I also made the test with a higher tyre pressure. As expected, this shifted the longitudinal forces as a whole down a bit and the optimum slip ratio went closer to 4-6%.

But why isn't it possible to outaccelerate an FZR with same tyres and same setup significantly if he just goes full throttle? And why is traction control also slower with FZ50 for example? If it isn't tyre physics what is it?

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 BWX232 :

Well that just confused me a little, because in that scenario you mentioned, it seems they would spin less than in RL- more in LFS? maybe a a double negative I didn't pick up on. But less grip = more spinning right? Or are you talking about JUST longitudinal grip and not lateral grip? I think you lost me on that one.

Yes, you understood me. I just talked about longitudinal grip. Cue Ball said, that the wheels don't spin as long and far as in real life. And thats the explanation I think ...

@cue-ball :

Easy to explain. At the moment something is wrong with spinning tire grip in LFS. They have to much grip.

1. They will accelerate much better spinning and therefore car is quicker in higher speeds, where engine power isn't sufficient to spin the wheels further ...


2. They generally have to much grip and therefore engine would need even more power than in real life to spin them.

Thats why they don't spin as long as in RL.

Greetings
RIP