rofl!

Can always count on Shot..

I hated it the first 10 laps

Then I realized it's just a sassy car giving me the finger, and I had to show it a thing or two about obedience.

Now we work well together... if only I wasn't mentally retarded at T1 of Summit Point, I would have decent times there. Running low 24s but am losing 2 seconds+ at T1 alone somehow...

Last edited by Ball Bearing Turbo, Fri 8 May 2009, 20:01.

Anyone else finding the SRF a little slice of heaven?

Quite a contrast from the Solstice but I'm really enjoying it. It REALLY hates coming right off the throttle, you have to be gentle with it on deceleration if there's any lateral movment going on.

Anything that minimizes backpressure on the impeller will obviously help with "lag" between shifts. On a relatively high pressure system, the mass of the recirced air can be more of a detriment to maintaining shaft speed than simply venting it to atmosphere. If you want to refer to lag as only the time it takes to pressurize a manifold from negative to max, then sure, it has nothing to do with that (obviously).

Quote from Nathan_French_14 :

If so, a blow off valve does not stop turbo lag. Its mainly there for noise, but it does help stop compressor stall.

Thus, between gears, it possibly can help with lag on higher pressure systems. Don't ever let Tristan tell you otherwise.

(I heard he kicks puppies!)

Quote from Bob Smith :

This has been posted so many times, yet my own testing in LFS has led me to the opposite conclusion. Excessive wheelspin does produce less longitudinal force in LFS, try the BF1 at the dragstrip with and without TC for evidence. Fastest times will be achieved with TC set at the optimal slip ratio. The question is that perhaps the dip after the peak isn't deep enough, doesn't happen fast enough.

True, and I can understand why people feel & say this though because in practical terms it's the way it appears. Especially at ridiculous slip ratios where you would basically just be floating on a film of molten rubber as it were.

It's a bit strange because: you can reach very high temperatures on the surface of the tire in LFS (per ctrl+shift) but it doesn't affect grip as much as when the core is heated, which once again just leads to a possible fundamental error in the relationship between the two. IE - if the core temp in LFS is 150 degrees, the tires feel like they SHOULD feel with a massive slip ratio ('soap'), even though the surface temps can meet or exceed those temps and yet the tire still has plenty of grip.

Android has in the past posted graphs showing LFS's longitudinal grip characteristics, and from what we could tell at the time there was a very small peak, and then a drop which levelled out as far as we could tell. The result is that you're better off mashing the brakes and inducing copius amounts of wheelspin off the line than you are feathering the throttle and being professional about it.

Quote :

I suspect that is modelled, although perhaps not well enough. I'd imagine that the humidity of the air would make a marked difference to the cooling effect, so that's potentially one possible avenue for improvement. Turbulence in the wheelarches might increase the cooling effect (or maybe even the opposite), and road tyres have a greater surface area than slicks, which must help, even if just by a tiny amount. We don't know how detailed Scawen's model for this is. Considering that we don't have hot brake discs warming the air that's cooling the tyres, LFS should if anything have tyres that warm too slow and cool too fast (although I couldn't say how large an effect hot brakes would have on the tyres).

Tires do cool faster on openwheelers in LFS afaik. I would suspect that heat transfer from brakes could be a concern, at least probably moreso on street cars without brakes that rapidly dissipate heat, but I'm no expert in this area. Pretty sure I've read something about it, but I can't remember what damn Captain Morgan!

Quote from Bob Smith :

Jeff, as DragonCommando quite correctly says, the majority of heat generation does come from the flexing of rubber (I think with says 90% comes from hysterisis), when driving in a straight line. Rolling resistance values are fairly well known and seem quite well done in LFS - this heat generation is what makes the tyre sidewalls warm up.

Are you saying that you suspect then that heat build up in LFS is derived directly from rolling resistance at the tire; at least when there are no appreciable lateral forces involved? (Ie F=CN and just using that force as part of the heat generating code somehow). Just for my own edification to understand the idea better. It seems then you'd have to come up with an arbitrary number as to how much energy would be lost into heat via hysterisis.

Quote :

What I don't know is how much heat is generated by the twisting and slipping of the contact patch over a surface. Clearly friction is an important factor here. If we take the 90% value from before, then when rolling along, this heat generation is taking about an order of magniture less energy than flexing (of a presumably well inflated tyre). How much it increases when a tyre is made to work hard is the big unknown.

Well, clearly it plays a massive role at the surface. I'm mainly talking about the interaction thermodynamically between the surface of the tire and the core of the tire, which seems suspect to me. Perhaps one of the issues is that it's currently modelled as two distinct areas (at least from what we can tell) and should probably be treated more like a dynamic gradient. The air inside the tire seems like it's a better insulator than the core of the tire, which I wonder about as well.

Quote :

Shotglass - could the fast heating yet slow cooling be attributed to a lack of cooling effect by the air, as the tyre passes through it? I would still expect a tyre to be heated a lot faster than it is cooled though.

There is cooling effect via air even now. (At least according to a post by Kid ages ago, and he was in the know about shit).

Quote from Gener_AL (UK) :

Where was I, ahh yes. More segments perhaps could help the tyre physics? balancing out the load produced when "givin it some".

It was stated in the past that he'd tried different amounts of segments (seems like a thing a prudent dev would do) and that no benefit was seen from more.

edit: Good to see you as well Eric

Last edited by Ball Bearing Turbo, Thu 7 May 2009, 16:26.

Quote from Matrixi :

The core temp should be predominately influenced by the stresses passed through the tyre rather than the surface temp of the tyre radiating inwards.

For these reasons I suspect LFS tyres tend to heat too quickly and also often heat in an unbalanced way i.e. driven wheels can maintain temp well while the non driven wheels often remaining less than optimum. This is also why you often hear that the fastest way to drive in LFS is to slide the car around more than you would in real life

Quote from Shotglass :

it has always struck me as fairly wrong how the rubber seems to be a fairly good insulator when it comes to colling the core but at the same time a very good heat conductor when it comes to heating it

*exactly*! It can't work so well both ways, this simply observable fact is a great place to start looking at this issue.

Quote from DragonCommando :

The temps of a tyre in LFS seem to be completely derived from friction, exept maybe for the sidewalls. where as in reality, most of the heat comes from within the tyre itself, as the rubber bends and flexes it generates heat, so unless you do a burnout, the surface temps should be somewhat lower than core temps. Its like bending a metal rod, if you have ever done it you will notice that the rod heats up where it is being bent. This is due to friction between the molecules of the material.

I haven't been around here a lot lately, but these snippets of info are the reason I used to read this place all the time. Well, that and Todd's thoughtful dissertations. Although I had to wade through a few piles of dung to find these gems, I'm glad I did. Maybe if Todd has a Miller Light or two he can post without charging us!

PS if you have nothing constructive and/or useful to say, go throw your feces elsewhere

edit: Heat from deformation is definitely modelled in LFS as proven by Bob in a thread I'm too lazy to go find right now, but it would seem that core temps are not derived with enough weight towards it, and with too much emphasis on direct heat transfer from the surface of the tire. Even without having concrete values to work with (good luck), tweaking a couple of coefficients could probably move the heating model closer to being more "correct" than it is.

Last edited by Ball Bearing Turbo, Wed 6 May 2009, 22:58.

Quote from Slartibartfast :

Didja read the post directly above the one I'm quoting?

I rarely read before responding

Indycars are on their way was well.

Quote from Slartibartfast :

Fanboy? No. It's subjectively evident.

Can I paypal Scawen for no reason?

Fixed the first part for you

And yes, you can pay Scawen any time you want to. Either buy thwacks of "skin downloads", or purchase some S2s to woo more friends. It think there was/is a way to just "pay" as well - hence all the people that used to put "S3 Licensed" in their sigs and whatnot.

Interesting, I would sum it up like so:
http://waynefontes.com/facepalm.jpeg

Quote from Slartibartfast :

Now that is another surprising observation I had. My first thought was, "I'll never be able to race like this and be welcome back for a second round." Then I tried my look buttons and flew right off the track.

Then I went to a practice session at VIR and found that my situational awareness is much more acute. Even with out the look buttons I just *know* where everyone is. I know that sounds cavalier, but I was passed and did some passing and dicing and not a single bump. My traffic anticipation was highly accurate. (Am getting used to the look buttons too.)

Heh, I find the same thing. The thing is, between the mirror, and what you can actually see, it's pretty easy to instinctively know what's going on, at least I find. In a moment of real uncertainty, having the look button set up for instant look can make you 100% informed in a fraction of a second if need be. iRacing's spotter can help too. On the other hand, high FOV used to acutally make it more difficult sometimes because it was so distorted. With a low FOV, I can run real close to other cars without getting worried about it

Quote from Zen321 :

Angling is very relevant though.

Let's not insult the intelligence of bass by associating them with the drifting community

Quote from geeman1 :

The thing is you can't change how people use words. Word meanings change over time and new slang words will form. There is nothing you can do to stop it. Fighting against it is pointless.
Arguing about them always ends up in shouting and name calling and in the end no one is any wiser, usually only more angry.

Watch the movie "Idiocracy". This kind of crap takes humans down that path.

I, one man, cannot stop the illigitimate and moronic (mis)use of words, but I, along with my grammarnazi(tm) collegues can slow the insidious corruption caused by filthy verbal mutations. I hereby call my bretheren to instate the Union Against Bullshit Terminology (UABT). Together, we shall fight to protect the DNA of terminology everywhere from gross infection by the vile disease of popus-culturitis (POP-us CUL-ture-EYE-tus).

Yoho mateys.

Last edited by Ball Bearing Turbo, Wed 8 Apr 2009, 20:11.

Quote from geeman1 :

Who cares? No need to fight over what words mean or what word to use to mean something.

That's a terrible attitude! Let's stop teaching language in school then too.

Fight bastardization!

Hurray for pop culture bastardizations of .... pretty much anything, this is no exception.

I'm off to take in some drag-gripping!

Quote from Slartibartfast :

Would need a monitor matrix of no less that 2x3 to see what is actually going on though. Could never learn a track like that.

LOL

That'd be sweet setup heh,

Or you could just run a 42" TV at 1080HD

Quote :

Here's an observation that surprised me somewhat. With lower FOVs trailing throttle oversteer is a bit more willing, the car seems rotate more easily. On the other side, power on oversteer is feels slightly less willing. I can use more foot. Monkeying around on curbs is much easier.

yeah I'm not sure why that exactly is but I find the same thing, I am able to be much more agressive and it feels more natural. I find it gives me a more accurate representation of the track to run lower FOVs. As for high ones... I think the false sensation of speed combined with less visual "resolution" of the track as it were makes it more difficult to be accurate and judge where you're really at and what the car is doing. Everything is too amplified to respond properly to at high FOVs. At least for me, I guess some guys run well with high ones. I know many WR hotlappers did them at around 40 or so however.

Hehe, yeah that's crazy FOV @ 95 - to each their own. I tend to run 55-65, but then my monitor is as close to my face as reasonable to compensate.

Just fun excercise to try - during a reply, set your FOV rather low at say 50 - and put your face right up to the screen. Notice how it feels fairly fast? Now back your face up 12" instantly - your sensation of speed drops off dramatically. Bob has an FOV calculator that gives you your most "true to life" fov for a given monitor size and viewing distance (as if you were looking through a viewport the size of your screen). Get a wall mount and put your screen at the right distance & FOV, and train your brain to like it.

Slightly OT: Is it bad for your eyes using and LCD quite close? I know with a CRT there is obvious concerns with emissions, what about LCDs?

Quote from Slartibartfast :

It would be fair to say that I feel the exact opposite. For the last 15 years or so I have pondered the relevance of ocular disposition on the sim racing experience. How big is the monitor? How far away? What shape is the eyeball? What, psychologically, are we expecting to feel?

I really can't imagine how any of these devs make a universally acceptable sim.

Yeah those are good points. I suppose all the banter in the world can't really do anything about these things... Universally acceptable, to me, means as close as possible to real world, repeatable, predictable (somewhat) reactions. A sim (to me) isn't about recreating a sensation, but about recreating a faithful reproduction - irrespective of how it's interpreted on the user end. The former is objective, the latter is subjective. I don't think iRacing spent gratuitous amounts of dough on their own tire testing equipment for no reason, and I doubt (though am open to being proven wrong) that the guesses of one sim coding superhero (as great as they really are) would happen to be more fundamentally correct than said testing.

Tires even aside (ahem), I am starting to get spoiled by the presentation - aural and graphical on the other side though. Especially the sound. Having voice chat is real nice, and the atmosphere "on the track" is really cool.

Quote from Slartibartfast :

I mean, flat in first gear in the Star Mazda from the apex out of 18 at VIR Grand West with full steering lock? I don't think so. It's even off camber. Not a chance.

Why not?

That mill has NO torque until high rpm, and your setup can allow that. In fact the default sets are rather safe. You could do the same thing in a comparable corner in LFS in the FOX. Think of the final turn at AS3R in the FOX.

Quote :

It moves too much over the road and not quite correctly so you get this sense of being loose all the time. Thrilling.

What.. the... Are you talking about iRacing or LFS in that sentence? Because that's very precisely how I feel about LFS. I drove each for 2 hours last night, and LFS is a constant game of managing how much you slide around, never feeling that the car is actually connected to the track for some reason. I better point out that I still really like LFS as well, and the difference between the two isn't really that huge physics wise but I find that LFS feels like you're flopping around like a rubber fish in comparison. iRacing is much more beleiveable over the limit - less controllable but nowhere near in an ISI kind of way. Drifting is possible and rewarding and actually requires some driver input in iRacing . I find that LFS rewards overdriving to a point, while iRacing punishes it.

Quote from Speed Soro :

Here I use it inverted, but this photo is before I disassembly the pedals and mount them directly on the wood.

http://picasaweb.google.com/lh ... 6QYGHDSLg?feat=directlink

That's pretty clean! I like it.

Quote from Slartibartfast :

If they are offering iRacing to the masses, it should be developed for the masses. If not, it should be marketed as such.

Actually... it's not really marketed towards the masses. That's why there's that whole speal about "training tool for drivers blah blah".

I'm sure they count on more people picking it up, but it certainly isn't marketed towards the masses. (No keyboard support? Forced cockpit view?)

Quote :

The literature says that you must use a wheel. It does not say anything about a load cell. If it did, I would have waited until June to try it.

Blimey, you sure as poop don't "need" a loadcell. I'm starting to think something is really really wierd about your setup. You're clearly having issues that you're either A) hyperbolizing beyond recognition or B) something is goofy with your setup for reasons I can't discern.

The only real difference between LFS and iR in terms of braking is that I can't just set the brakes to some arbitrary value to keep them from locking up - I have to use my foot, and as the video Crommi posted shows, it really isn't that hard. If that video was LFS, the user would've had a "setup" that allowed him to smash his pedal to the floor without thinking about it... My experience mirrors that shown in the video, and I think Phil's does too. You seem like a bright fellow, so I don't imagine A is the answer - it must be B. And I hope you get it sorted because it's ruining the sim for you!

I support this message

ts;dr:
+1

Quote from Shotglass :

the wheels also have quite a bit of rotational energy in them that needs to be burnt off before the brakes can lock which will make a cars ability to lock its wheels speed dependant
although if you own a race car and you cant lock the wheels at speed you should probably fit better brakes

AH, this is what I was getting at. In one sense that sounds breathtakingly obvious and yet the practical effect of that wasn't obvious to me. It's not *just* the friction between the road & tire, it's the energy in the wheel that needs to be overcome. Hurray for a better understand of things that shouldn't have to be said!

One thing I do note in iRacing, which I could use a better explanation of, is the fact that at high speeds one can use full pedal travel for a short time before having to back off. On their forums someone explained that this makes sense. I notice it too, and to brake as late as you can you need to employ that technique of loading them right up and backing off again, to the right spot - otherwise you will get a lockup leaving the pedal all the way down. I don't really understand the forces at play there - presumably is the same reason you can slam on the brakes in your car and often just before you come to rest they'll lock up, given equal braking pressure. ... ?