Quote :

Welcome, mpn89.
You last visited: 23rd August 2007 at 01:46

Didn't register that long ago but it's been over 3 years since I've logged in.

Just reinstalled LFS after a long hiatus.

Maybe before forcing others to buy lfs licenses you should try it yourself.

Pictures in signatures don't bother me simply because on any forum that has them allowed I simply turn them off in my CP.

Another quote indicating the importance of running within the correct pressure range from an Atlasf1 article:

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However, the large F1 tyres are designed to have their optimum profile at a certain level of inflation, and for that reason there are limits to how the alteration of tyre pressure affects performance. Also, of course, racing tyres operate at hot temperatures. As air expands with increasing temperature, it is important to predict how the pressures vary over the temperature range so that a tyre can be set 'cold', and the heat will expand the air to the required 'hot pressure'. This is done by constant monitoring of the tyre pressures and temperatures, as well as being part of the reason for the use of tyre warmers, which pre-heat the tyres close to racing temperatures.

The article gets hard and soft mixed up towards the end of the when talking about wets.

Quote from Viper93 :

I still don't see this. Less pressure you will have more grip, more grip you will have more heat, heating the tires faster. You cannot go too low because of cupping and sidewall flex, but still.

Exactly, you can't go too low - that's all i'm really saying, in lfs it seems to work. If your tyres aren't heating up enough within the optimum pressure range you don't go 10psi lower to generate heat because you'll be generating the heat on the sidewalls rather than where you want it and can 'cause tyre failure. First priority is to have the tyres within the correct pressure range, second priority is to have the tyres at the correct temps. You will never be able to drop tyre pressures 15psi to generate heat if you're running at near freezing temperatures and your compound isn't soft enough - you do the best you can by setting the car up for maximum grip but you don't ruin the shape of the tyre 'cause you'll just lose more grip, and yes you will probably want to run the pressures lower, but only within the narrow operating range, you would still run them higher in qual than in a long race though. The best way to get the heat up in a too cold situation is a softer compound but if that isn't there then softer car, increase toe, and through the car around more to generate heat.

Tristan pretty much covered what I also mentioned earlier, the pressure envelope is quite narrow (~5psi), so you can't be going around making setup changes by drastically changing tyre pressures - we're not in 1950 anymore. Within that small recommended envelope maximum Cf is probably generated at the lower end of the pressure, it's just that you really need to be very close to the optimum pressure all the time.

Quoting Mr Paul Van Valkenburgh:

Quote :

The proper pressure is one at which there is an even rubber pressure in contact with the road, all across the tire patch. Pressure must also be at a minimum, to get the maximum rubber area on the ground and provide some bump absorption, and yet it must be high enough to minimize heat generating tyre deformations (in lfs hotlapping low to creat tyre deformations:tilt...

The most general statement that can be made is that in the range from 20 to 40 psi, the Cf goes up slightly with increasing pressures, except as it can be greatly decreased by track roughness.

So what I am talking about is that in a short stint you need the pressure higher so that you are at the optimum pressure when you go for your most important lap, but in a race that would mean lap 2-3 would be at optimum pressure and above that it wuold be too high. In all real life aplications I've never seen or heard of people going with a really low pressure for qual, and then raising it for the race, there might be exceptions of course but I haven't heard of them. If you had to use low pressure in qual to generate heat you also have to do it for the race.

We simply do not want the heat that is generated by sidewall flex to be the way we generate heat in tyres - that is why touring cars with the tyres enclosed (enclosed=less cooling from the air) have very low profile tyres, whereas single seaters can have larger sidewalls. We generate heat in the tyre with the car setup and also distribute the heat with car setup, not by running low pressures.



I'm not saying that the LFS tyre physics seem to be completely wrong, just that the tyre pressure performance envelope seems to be a bit off. All the other factors are right to a certain extent imo -> less pressure = better road compliance and more rolling resistance and more grip, but IRL you want to run HOT qual and race pressures very close to eachother or you're simply throwing away performance, in lfs it isn't the same. Another thing I don't know if lfs simulates or not is the large amount of effect download has on the shape of the tyre - on an oval you run much higher pressures because the download at high speeds will push the tyres down and will assume the same optimum shape they would've with lower pressures on a street track at low speeds with less download.

An interesting thing about tyre temps is that LFS perhaps always displays the average reading or "pit reading" - not peaks, or it doesn't simulate peak temps? IRL tyre temps vary greatly while on track from and can go from 150 degrees f to 370 degrees f within seconds during a turn. Valkenburgh had some figures of tyres cooling at 50 degrees fahrenheit per second down high-speed straights from their peak temps after the corner. This is why you see tyres "shine" in corners and then go dull again on straights.


I was getting confused typing.. parts of my post might not make any sense. illepall

An example of tyre pressure trickery that can be used and also illustrated my point of running higher pressure for low runs: In a kart race where you have maybe 2-3 warmup laps before the green flag is thrown the lead kart determines the speed - and in effect also determines how much pressure buildup everyone is able to generate. He can choose to run pressures 1-2 psi higher like in a qual setup for a 15 lap race and then proceed to lap the warmup laps very slow, so those that have put race pressures will be struggling for the first few laps and by the time their tyres come in the leader should be well on his way.

Googling I found that some nascar sim setup guides say it right "run higher pressure for qualifying than you will for the race"

Quote from Viper93 :

mpn89 I don't know how you drive but your comment is backwards and should be the other way around. A lower pressured tyre will increase rolling resistance, resistance creates heat, thus bringing the tyre up to temperature quicker.

But it will be at the wrong pressure and will heat up at the wrong places.

Tyres are designed to reach their optimum shape and work most efficiently within a certain (narrow) pressure envelope, outside of it they won't work good. A tyre at the optimum pressure can be worked harder than a tyre at the wrong pressure because you get the most out of it.

When the ambient and track temperature is lower, do you run higher pressures or lower pressures? You run higher pressures because the tyre needs to reach it's optimum pressure. Same goes for a short qual-run - a slightly higher pressure than used for a race means you'll reach your optimum for your first flying lap. If you run the same pressure for the race you'll be fast for the first few laps but then fade off.

In LFS the pressure envelope seems way too large - if you were to run low pressures for qual IRL you'd end up overheating the tyre shoulders and never been at the optimum pressure = never at the fast pressure. And for a race IRL the pace drops if you have high pressures because the center overheats too much.

Quote from AndroidXP :

I think the tyre rolling over respectively the surface "crumpling" together at too low pressures isn't modelled yet, which makes low pressure tyres too effective.

I was thinking along the same lines. IRL you will put a psi or two higher pressures for a short qual run (1-2 laps) because you want the tyres to be at their optimum pressure right away on your first flying lap - and in a 20 lap race for example you are a few psi lower because you don't want to be fast for 2 laps and then fade off - you want them to reach optimum well into the race rather than at the start.

In LFS it seems you put way lower pressures for a qual(hotlap) run - and then pump them up for long races, which is opposite to real life imo.

I think LFS tyres have a much larger operational window with regards to the optimum tyre pressure than you have in real life.

yeah the tyre physics are good, but not excellent yet.

Soft kart tyres don't squeel, and neither do soft rain tyres, only the hard compounds do.

Quote from kompa :

Guys(esp. Tristan), how realistic do you find the tire sounds in nkp? Slicks in particular. I never hear them squeal, just a big swooOOSHhh when I spin. Is that correct at all?

In the single seaters I've tried i can't say I can hear the tyres much, the engine + wind noises overpower any noises the tyres make, I assume when you spin on dry asphalt you'd hear the screetch. Locking up in the rain you can hear a bit of a sound, very subtle, locking up in the dry if it's only a tiny lockup it's not easy to hear, for fronts a tiny lockup is a lot easier to see than hear, and for rears you can feel it (and hear it but not through tyre sounds).

You definitely don't get the loud understeer squeel on proper slicks as you do in lfs, or the sliding noise from oversteer/drift - you're able to feel the understeer/oversteer a lot easier whereas in games you need the unrealistic sound to help you realise it.

I haven't tried nkp.

The one problem with charging for tracks would be that there wouldn't ever be enough buyers to make the online racing any good.

I have no idea what licencing issues are like for tracks, but you'd think some less-famous tracks could be willing to let if happen even for free? For example Johor in Malaysia ( used to host MotoGP ), Bira Circuit in Thailand ( great for XFG and other slower cars in LFS ), the many smaller tracks in Europe as well. Just a thought.

Quote from bootlegapparel :

I've only ever used left foot braking in front drive cars mid corner, it's really the only time you should use it

using it consistantly is a bit of a bad habbit

Except in sequential dog-box cars you stand to lose out if you don't left foot brake into almost all corners imo.

Gentlefoot: now that's talent! Do you use your ass to see where the road is going?

Quote from mrodgers :

I do believe you have your right and left mixed up.

I of course just assume that you have left/right mixed up .

I don't think he has his feet mixed up. I also occasionally drive with left foot for both gas and brake in an auto.. and then if I really want to have fun in a Manual car I will use right foot for clutch, and left foot for brake and gas. illepall

The one time I can thing of locked brakes being good is when you're in a high speed spin and you know it isn't going to be good... hit the brakes HARD with the other foot on the clutch until you hit something or (hopefully) come to a stop without damage.... in LFS nobody gives a shit about damage though .

ajp71: In a car with lotsa downforce you absolutely slam on the brakes really hard early on because there is so much grip being generated by the downforce that you can slam on the brakes without locking them.. so it's not necessarily how the brakes/tires are designed but because of the downforce available... then you have to ease off because you lose downforce and of course because you start steering.

I don't get the "locking the brakes to catch a slide." Care to explain how it works? The way I see it is to catch a slide you need more weight on the rear.. definitely not locking up the brakes so that the weight is transferred to the front, which results in even less grip in the rear. If you're understeering through a corner you get off the gas and maybe a bit of brake if you're in real trouble... I don't see how doing the same thing could help you get rid of a slide.... except that when you completely lock the fronts you overload them and they lose grip, but with locked fronts you also lose all steering.


"Locking brakes on gravel = shorter braking distance": I don't see how this could be true for anything except really deep and soft gravel.. with any kind of a hard base and loose gravel on top proper braking with proper tyres will stop you much faster than locking up, I could be very wrong though.

Quote from Becky Rose :

As is well documented now I think, I race karts, and I have to disagree. Nobody pays me the slightest bit of attention when I turn up for a race in a new crowd/series etc. I get the odd look that i'd get anywhere, but it's not a suprise to see a woman at a race track wearing overalls.

I agree.. I've raced with a fair few women in karts and many of them have been pretty damn good. I've heard stuff like '"She's way too agressive, she's running everyone off the track" ... but I hear the exact same about all other drivers that drive in the same way.

Quote from Bramski :

you can bet your bottom dollar that the woman will back off first, and that's not because they're weaker than men, it's because they're not being driven by testosterone.

I disagree.. because if you're letting testosterone control how you drive especially ito a braking area you're an amateur driver doing his first few laps in a race car. To be fast and cool under racing conditions you don't get overcome by testosterone.. that only happens the first time you drive a faster car/bike than you have before and goes away after a lap.

Quote from Scawen :

Don't worry, I am aware that the sequential boxes aren't right at the moment. In fact sequential gearboxes aren't simulated in LFS at all.

I expect to start working soon on some gearbox updates and also the false starts system, and try and get several incompatible updates into the incomaptible version. By the way, it's not just the sequential boxes, I'm not really happy with how the road car boxes work either.

Wicked.. sounds great.. falls starts are cool as well.

One would hope that it depends on the forces acting on the tyres.

modenaf1: I'm aware of how to double-clutch and heel and toe.. the problem in LFS is with sequential shifting.. they behave nothing like they do in real life for upshifts.

Nobody I know in racing with a sequential dog box uses the clutch for upshifts, it would be a waste of time and is more damaging on the components than not using the clutch.

Simulating clutchless shifts in games accurately is probably a lot more difficult for H-pattern synchro as you need the forces in the gear lever to come into play to accurately shift, and shifting clutchless in an H pattern car should by all means be a lot more difficult in LFS than real life because you can't get the same feel... but with a sequential dog box you literally just smack the shifter, no delicate feel required.

Last edited by mpn89, Thu 29 Jun 2006, 17:00.

Quote from mrodgers :

It's because a - it's only a 3 man developing team and b - they are doing this because they want to create the best simulation of racing, not make the most money they can. Give it time.

Yeah.. am aware of the above. I tried the demo for the first time a few years ago and have seen lots of improvements since then. I was simply amazed at how similar the experience to realising how much downforce there was in the S-S cars over the first few laps was to real life.

XCNuse: I think not being able to shift with the single seaters/other sequential cars like 90%+ of real life race car drivers do is reason enough to have it high up on the fix list. The first thing I did with S2 was turn autoclutch off, and go out trying to shift up but not being able to unless I tapped a clutch button.

Quote from XCNuse :

no reason in putting it in improvements again im sure that after about 4 or 5 so years now, the devs know about it

ah good to know.. i guess there is not much interest in fixing it then?

This is one gripe I have with lfs since getting the S2 licence about a week ago so I'm just bringing this thread back up.. perhaps should start a new thread in "improvement suggestions"?

In any kind of sequential shift car, such as a formula bmw, formula renault, f3, etc etc... it is extremely easy to do clutchless upshifts/downshifts.. the only time you need the clutch in sequential cars is on starts and pitstops.

In lfs only the downshifts with blipping works, upshifts seem near impossible.

The upshift in a sequential car works with just a tiny and very quick lift of the throttle to help disengage the gear and simultaneously pulling the shift lever.