How does LFS's longitudinal tyre physics compare with these?
Does anyone know a way to extract the shape from LFS? The overall shape of the acceleration graph is fairly correct (it would seem, from driving), but the dip with excess wheelspin is perhaps too little.
Peak seems quite early in LFS, but then quite late on the textbook one. With the curves being affected so much by construction, inflation pressure and load, both could be correct, under differing circumstances.
Wouldn't trust that textbook 
. Normally, with genuine data, you'd see points being plotted here and there and a curve to match the data. That just looks like what someone thinks those curves would look like. 
. Normally, with genuine data, you'd see points being plotted here and there and a curve to match the data. That just looks like what someone thinks those curves would look like. Though I think most people agree that the longitudinal grip doesn't drop off enough in LFS, considering that in real racing full throttle starts are far from optimal while they are the norm in LFS. I'd say the peak is too short and hard to stay on, whereas the drop-off is not severe enough, at least in the higher slip ratio regions.
Then again, you shouldn't forget that modifying these curves would do far more than "fix" race starts. Driving dynamics in power-oversteer situations would change dramatically (maybe to the better?), with the tyres giving away quicker on throttle, while at the same time coming off the throttle would have more of a stabilizing effect than it has now. Maybe outright drifting through corners with a locked diff (just look at some FZ50 WRs) would then be less effective, too.
Then again, you shouldn't forget that modifying these curves would do far more than "fix" race starts. Driving dynamics in power-oversteer situations would change dramatically (maybe to the better?), with the tyres giving away quicker on throttle, while at the same time coming off the throttle would have more of a stabilizing effect than it has now. Maybe outright drifting through corners with a locked diff (just look at some FZ50 WRs) would then be less effective, too.
things that make it harder to drift=bad. It seems pretty realistic to me actually. Maybe not "textbook" but if you start a race in the fz5 with full throttle, your driving force drops quite a bit when you just spin.
Do you drift these sorts of cars IRL? TBH I think it's quite easy to drift in LFS, although I've never really tried (in LFS and certainly not IRL either), so while not qualified to talk either, I can say that in most cars I'm rarely worried about overstepping the limit. Massive powerslides are easy to hold.
sometimes is really easy, just get one of the inferno drift sets and try, you can start a drift without even lifting off the throttle.
The combined braking and cornering, and accelerating and cornering graphs should look like this apparently...
Where's that from? Thats the closest thing I've ever seen to a full description of a tyre. Ready to create some LFS graphs Android?
A giant book on high performance tires I found in my university library. It's pretty mental some of the stuff that's down in there.
I found another one on turbochargers, but the maths was so horrendous I couldn't even work out which equations would be most helpful to post! i think the devs are just going to have to wing it on that front!
I found another one on turbochargers, but the maths was so horrendous I couldn't even work out which equations would be most helpful to post! i think the devs are just going to have to wing it on that front!
Maybe you can find out the name and author?
Yes, please try to find out author and title.
I'd like to know what sort of tyre it is. Radial or crossply? What sort of tread, if any? What sort of compound? Width? Pressure? Tyre wall height? Any information, actually.
Thanks for posting the picture.
Vain
I'd like to know what sort of tyre it is. Radial or crossply? What sort of tread, if any? What sort of compound? Width? Pressure? Tyre wall height? Any information, actually.
Thanks for posting the picture.
Vain
Phew, really hard to get data to show this kind of stuff in LFS - I mean, not in principle as it would just mean driving lots and lots, but in practice the RAF extract tool seems to crap out at > 3-4MB RAF files, which greatly limits the amount of data I can get into one graph. So, please take the attached image more of an "artist's rendition" rather than factual LFS-curves.
I made these curves by limiting the slip ratio range to a 4% span and moving it around from 0 to 100% slip, drawing a line through about the center of the shown data points at certain percentages. Actually in motion you can kinda see how the curve wanders and flattens out
I made these curves by limiting the slip ratio range to a 4% span and moving it around from 0 to 100% slip, drawing a line through about the center of the shown data points at certain percentages. Actually in motion you can kinda see how the curve wanders and flattens out
I'll get it out tomorrow, and steal some more valuable information from it.
I'll get the brake design one out too. Check back later
I'll get the brake design one out too. Check back later
Whilst full throttle starts may be the norm and since patch P have been realistically possible in all cars (excluding BF1 with the TC off)
they are far from ideal. Racing on the Redline racing server with LFS Lapper, the most annoying InSim app ever made, I was observing the 0-60mph times and noticed they could range from about 3.0 to 3.8 seconds at Blackwood, this figure is irrespective of the reaction time. On the slowest run I was half a sleep and just floored it when the lights went green. I reckon that controlling the right foot is very definitely worth it if it can give you an easy best part of a second on the opposition
Though maybe Blackwood is a bad example, considering that the grid is on a slope with a different inclination depending on which grid position you start from
Hadn't thought of that :doh:
Android, how you do your wizzardy to get these things out of LFS is a mystery to me, but if anything, keep going!
These curves aren't new however, they've been available for ages (since 2004 iirc) online: http://insideracingtechnology.com/tirebkexerpt2.htm . They look a bit text-book-y but they do probably give a good indication of the phenomenom (sp) of force combining, not that I really have any clue as to why this happens this way.
These curves aren't new however, they've been available for ages (since 2004 iirc) online: http://insideracingtechnology.com/tirebkexerpt2.htm . They look a bit text-book-y but they do probably give a good indication of the phenomenom (sp) of force combining, not that I really have any clue as to why this happens this way.
Ok so this is the book:
http://insideracingtechnology.com/booktiredescrptn.htm
(didn't want to post the title here because google will index it and associate it with those images)
The tyre is inferred to be a modern Radial tyre, one of the more expensive street ones, it is "low profile", the tread pattern is street legal in america. That's about as much as they'll give away, apparently the tyre industries biggest product is secrecy!! Pressure at "recommended", so probably around 30 psi. Tyre width of around 235 going by other examples.
The reason these daigrams are all a "bit textbooky" is that they were not allowed to paste actual test results from the test facilities because that would give away a lot to the "enemy". So they've traced over them, and ditched the names, lol.
"Radial tyres are better because they have a stiffer, flatter contact patch, and there are higher restoring forces at lower values of lateral tread distortion, which translates to smaller slip angles for the same lateral force as bias ply tires. Smaller slip angles in turn mean less drag, and less heat."
We should chuck some bias ply's on the UF1 - not as sensitive to camber, and plenty of warning at break away so easy to drive at the limit - perfect for n00bz
http://insideracingtechnology.com/booktiredescrptn.htm
(didn't want to post the title here because google will index it and associate it with those images)
The tyre is inferred to be a modern Radial tyre, one of the more expensive street ones, it is "low profile", the tread pattern is street legal in america. That's about as much as they'll give away, apparently the tyre industries biggest product is secrecy!! Pressure at "recommended", so probably around 30 psi. Tyre width of around 235 going by other examples.
The reason these daigrams are all a "bit textbooky" is that they were not allowed to paste actual test results from the test facilities because that would give away a lot to the "enemy". So they've traced over them, and ditched the names, lol.
"Radial tyres are better because they have a stiffer, flatter contact patch, and there are higher restoring forces at lower values of lateral tread distortion, which translates to smaller slip angles for the same lateral force as bias ply tires. Smaller slip angles in turn mean less drag, and less heat."
We should chuck some bias ply's on the UF1 - not as sensitive to camber, and plenty of warning at break away so easy to drive at the limit - perfect for n00bz
Thx for the info. Certainly gives a good idea of what combined forces should look like and sounds as if the source is a real testing rig. I wonder if these kind of graphs could be created for other sims, LFS doesn't seem to be looking too bad.
We already have bias plys in LFS which is the most glaring "problem" with what we currently drive with.
Android at what kind of tyre pressure and with which type of tyres did you record those curves?
Either way in relation to the textbook curves their peaks are a lot further to the right, and they also flatten in a distincly soft fashion over as much as 6° possibly causing the spongy, icy feel of lfs.
Both these problems are much more pronounced at 10% slip with ~8% being optimum in pure longitudinal slip situations, so an optimum exit will likely be in the ~5% slip range, which with a little guesswork puts the optimum slip angle out as far as 10°.
In other words the cornering stiffness in lfs is very low, much like youd expect from a bias ply (likely made even worse with underinflation as used in hotlapping setups), causing the cars to go very sideways through corners and making them react sluggish to driver inputs (this could potentionally lead to the hard to drive setups you find regularly in lfs that have to compensate for sluggishness with added oversteer in the springs arbs and diffs).
edit:
Whoops didn´t look at the filename so its the XRT with what i assume are road supers with a fairly low profile meaning they should have a fairly high cornering stiffness by rule of thumb. Still leaves the pressure question unanswered though.
R2, 120 kPa, it's in the pics.
i meant the combined load curves which are obviously not done on r2s and without any mention of pressures
How does LFS's longitudinal tyre physics compare with these?
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