This makes no sense if it's a complete pile of shit as you're saying. DaveK's held lap records and won races in the real car. He ought to know himself if it's this far off.

Personally, I think it's off when it slides. It does odd things then. Not to mention it loses all grip in the next turn. When out of shape it can feel like the sidewalls have lost rigidity and squirts you this way and that. But generally, it feels there's no tolerance around the limit - one moment there's grip (such as there is) next it's ice - "i(ce)Racing".

But I still say we don't know how much of that is lack of physical forces telling us what's about to happen - only eyes and ears. What *should* that be like to drive?

Thanks for the reply MadCat360. Do we know what kind of Brake bias is normal in the RL Skips? This isn't so much of an issue in the iRacing version if the BB is around baseline setting FWIW. Although I'm only talking about using a couple of notches back.

You are coming right off the brakes there when it happens though, whereas my issue is more mid way -where I need to pause on the brakes if RFB.

Yeah, I've not had pure power oversteer there.

As always with RL footage, I'm struck by how small corrections for the things you can obviously feel in the car, that we can't really see, keep it all under control.

Probably works both ways. E.g. Todd recognised something visually wrong with the sim, that I expect an F1 driver looking at it wouldn't register. But put an F1 driver in a real car and they'll unconsciously feel subtle changes in balance and yaw very early before anyone's eyes could pick it up and that's how they can drive a car on the limit.

Quote from jtw62074 :

Next time you slide a car, steer into the spin instead of out of it. If the car straightens up right away it's all because you reduced the front lateral force a bunch by increasing slip angle. The more you feel that, the more difficult the car is to catch probably.

I've not heard much about RL drivers using understeer-type behaviour in the way it can be used generally in sims. Could be it destroys the tyres. and also that outside of the US it's mostly RFB. But it doesn't seem to have the same advantage. In RL they just correct with countersteering, as well as adding throttle and coming off the brakes. It does seem there's a common factor in a lot of weird behaviour to do with the over the limit grip falling off, and once tyres start sliding their continuing even though the cause has been removed.

But there's the other thing - how difficult would it be in RL to control a car on the limit without your inner ear and other physical sensations telling you when it's starting to yaw etc? That does make it difficult to compare 'difficulty'.

MadCat360: interesting about the Skippy. Do you think that's with or without the front sliding a bit due to excessive braking. Because that would cause sudden oversteer if you come quickly off the brakes in any car when the front is sliding and the rear is already loose.

OK, that sounds quite reassuring then, about moments of inertia. Thanks for that info Todd.

Yeah, I'm very aware of the illusion created by chase views focussed on the centre of the car, and in all sims the movement looks odd from that point of view. I *think* I'm taking this into account. I'm seeing this movement based on simply staring at where the wheels are on the road before during, and after the process, and that sometimes they seem to follow pretty much the path I'd expect if the car were cornering normally at 10mph with grip instead of violently snapping back at 100mph. I'd expect another bout of sliding at the rear after that. I'm open to persuasion on this apart from anything because it's horrific if they've got this wrong, but it still looks to me that it appears on rails all of a sudden. It could, I suppose, be a consequence of the sim producing stupid/unlikely inputs from us drivers i.e. in RL you'd almost always get the front wheels straighter quicker, after the snap. To my mind it comes back to inertia again though; *visually* the rotation seems to accelerate too fast after the snap and I can't see the rear tyres holding on perfectly afterwards with that much mass moving that fast sideways.

It is worrying that you immediately spotted the yaw velocity issue with 2 cars but DK didn't. It does rather blow to pieces the notion that these cars undergo precise tested for realism, and by pro drivers too. It seems more a case of stick it out there, and if enough people complain about something, then change it next update.

Trouble is, I think generally the pros probably drive within realistic limits but sim drivers take the physics to extreme places - where there be "singularities" and the like.

BlueFlame: I've an image in my mind of someone driving on the grass in a smooth circle, and DK confirming the lateral g is what it says on a table on his 'puter, but no one actually noticing that if you lose a bit of grip for a moment at the rear then you spin around in circles for ever!

Last edited by Postman Pat, Thu 29 Dec 2011, 18:32.

Todd,

Regarding the axis of rotation. It's mostly watching from Far Chase view. What looks particularly wrong to me is where someone gets out of shape at high speed on a straight. They countersteer, get a snapback, and the car seems to rotate on a coin. If the snapback was that violent, I think the opposite rear tyre (outer one after the snapback) would then probably slide too, so you'd get the pendulum/fishtail effect around the front end. The rotation would then be slower. But that rear seems to grip and turn the car as though it was normal cornering. I'd have thought that if the snapback is that violent, then the rear should slide afterwards. If not then it wouldn't be such an issue to bring under control anyway.

BTW, slightly different physics point... Once you've got a difference in lateral force between front and rear, then the angular acceleration produced is a function of I (second moment of mass or 'moment of inertia') about axis of rotation, right? (Torque =I x angular acceleration). How does the programmer calculate I? You need to integrate the equation of the volume of a known mass about an axis, surely? Anyway, if that's wrong, mightn't it explain why a touch from another car, or blade of grass causes a sudden angular acceleration! I've know idea how you guys work out these things.

With the MX-5, you can get a slide going, let go of the steering, and the self aligning torque will generally point the front wheels in the right direction. But good luck catching the snap that way because it's ridiculous IMO. There are only a handful of guys doing faster times than me in the MX-5, yet I've spun out at Okayama at really low speed, and I've seen the situation developing, but you might as well be holding your dick for all the use steering is. Unless you jump on it early and overcorrect, and then you've got the snap to deal with. You can usually muddle through with the brakes as well - which shouldn't really work should it locking the front tyres in car with ABS?



Dave, yeah, when I've seen a really fast RFB lap in the skip it's either been a case of virtually no steering involved in the turn-in, i.e. the driver's made the slightest suggestion of a turn in, and as soon as he's begun trailing the brakes it's rotated in on it's own (usually needing countersteering to control that as well!). Or, the extreme opposite; tons of steering in order to induce understeer so that the front doesn't grip much either to balance it out. Bottom line is that if the front is gripping and the rear comes loose it's bloody hard work.

BTW, the oversteer whilst releasing the brakes I referred to isn't jumping off the brakes, it's just a fraction faster or slower. It may not happen other than when cornering on the limit. So maybe it's to do with this front sliding a bit but then releasing the brakes a *touch* too fast cause them to grip all of a sudden. I notice it doing RFB (where you can't feed in throttle to help); I'm find I'm wanting to smoothly trailing off the brakes but something tells me to pause the process because it'll snap loose if you let it off any more. It all seems to revolve around being too icy generally with the tyres though. They should suck the road up a bit more. If you've seen the RF2 vids, those tyres look good and grippy.



Re grass. ..Yeah, if you get on the grass in 3rd gear stationary, add a bit of steering, touch the throttle to momentarily lose grip at the back, and you can then keep the rear wheels spinning forever (like you were flooring the throttle) just by literally touching the throttle every second or so to keep them going. So again, any rotation driving, and it's either fast and frantic correction or lock the front.

The $64K question is whether the sim physics is actually more difficult than RL, or someone like Todd's mate simply not adapting to the sim environment.

Last edited by Postman Pat, Thu 29 Dec 2011, 04:12.

Quote from jtw62074 :

The iRacing "never ending spin" thread was talking about low speed spins that were really pretty out of whack and generated a lot of debate.

Todd. Sort of related, but I'd like to ask you about some issues, since you have knowledge on this stuff.

IMO, slow speed spins still happen in the MX5 and Skip. It feels like you countersteer and balance the throttle but there's no discernible effect, you countersteer a bit more, still no effect. Then you add a little bit more steering and it very suddenly slows the rotation and snaps back. Now I know 'snap back' is real, but it's as though you need to overcorrect to stop the rotation. And then when it snaps back (including at high speed), visually it seems to involve the car rotating around the central axis rather than the rear pendulum-ing (if that's a word) around the front. After all, that's why that sort of thing is called "fish-tailing" when it happens repeatedly. The central rotation makes it much harder to straighten in time, and lots of experienced skip drivers are snapping out of control like complete novices. I think LFS is the only sim that possible makes this look (at least) realistic by having the rear rotate more about the front rather than the rotation being about the central axis. Any thoughts?


One other *important* thing. In the Skip, when you trail off the brakes at the turn in to a corner, the faster you come off the brakes the faster the car rotates in. Surely that's the opposite of reality - where coming off the brakes should increase rear grip? Indeed, RFB-ing in real life involves coming off the brakes faster so as to get to the throttle quick whenever there's any sense the car is about to over-steer. The fast Skip drivers all come off the brakes very smoothly and it's written into the community-made manual that it's important precisely because coming off the brakes too fast is a cause of spinning. Surely that isn't how it should be?

Quote from Jshort :

Netkar is amazing. Biggest head scratcher for me about netkar is why there aren't more drivers.

Well, it feels the best to me off all sims. But I've heard the netcode isn't good.

And then there are bad aspects. The skid noise is ghastly. And in the garage, you start the engine and you begin rotating on the spot. Thinking aloud here, I believe the Pacejka magic formula is normally fitted to be optimised at a particular speed range...or something, and will produce worse behaviour at the other end. I thought NKP was meant to have a theoretical model rather than an empirical/Pacejka type, so I'm wondering what that's all about?

Then there are those invisible marshalls with yellow flags. I'm scared of those flags. I keep thinking they're operated by ghosts of dead racing drivers.

Quote from Gnomie :

Also, I like the sound in general, and the crispness of the graphics.

It astounds me when people say this. Both sound and graphics are, for me horribly sterile/synthetic. I never stop thinking 'this is a computer game'..ever. Which is actually not true of other sims. And I know I'm not the only one who thinks that. Still, LFS sounds really bad too IMO. The sound is what makes it impossible for me to 'enjoy' iRacing.

Quote from Tim NL :

The iRacing.com Member Website is currently down for maintenance.

There see, iRacing are fixing the problem identified by Peterules already.

Just tried the Skip.

It's got a better sense of lateral weight movement to how I remember with the OTM. It's more like a process going on now rather than an instantaneous result, which is how it should be handling mass/inertia.

But there's still not enough grip at low speeds over the limit - which was supposed to be a Pacejka problem. I saw a top Pro spin out in a race and I found still the rear tends to accelerate away from you like on ice if you break traction in slow corners. And on the grass you can still do mad spinning things by just touching the throttle at the right time. The snap-back at low speed is brutal. The NTM was supposed to fix some of this.

Still hate the engine sounds and they still glitch when you hit the limiter, but the tyre noise is improved. Track (and everything else) still looks grey and gives poor sense of distance.

I stayed in the pit for a while then noticed there seemed to be bits of pit texture inside my car once on the track. That made me feel nostalgic for dodgy rFactor mods.

Quote from Bawbag :

.....if a bit understeery until the mad snap oversteer...

What do you think the chances are that the snap is real and it's just that there's no seat-of-the-pants feel to warn you? After all, they say the eyes are the last thing to know in real life.

Quote from Hyperactive :

It is just a marketing failure imho.

That's one way of looking at it.

Trouble is, DK is not the marketing department (true, it can be difficult to differentiate at times). So when he announced that his 'general theory of rubber' was accurately predicting tyre behaviour in ways that weren't possible with the bog standard Pacejka + low speed fudges, but then had to partially roll out something that clearly didn't work generally on all cars and tracks and is apparently playing up in obvious ways to many (it seems) even on what has been put out, then that hits his credibility. Most people haven't experienced RL track driving let alone open wheelers, so a lot of this is about an act of faith in iRacing's claims of realism.

The problem is, even if it starts to behave acceptably after 'adjustments', I'd find it difficult to trust anything again. But I'm sure the legions of loyal investors will differ.

So how can they release a NTM that within hours people say is clearly wrong in basic ways? I hear they're going to make modifications based on user feedback . iRacing are supposed to be the experts! They're not amateur rFactor modders sitting in bedrooms making guestimates gleaned from odd bits of technical info and videos they've managed to get their hands on. They've shed loads of money, access to real technical data, and presumably therefore, pro drivers to validate the physics - or so we're led to believe.

I'd never really subscribed to the view iRacing was expensive hype - overly commercial yes, but basically better than the rest. There was always the issue of certain features lacking or poorer than some other sims, but the justification was that iRacing takes accuracy seriously and does it right. That argument's gone down the pan then.

Expect it's cheered Scawen up a bit though.

Blimey! Think I might have to finally get myself an LFS license (been a 'conscientious objector' for so long now I've forgotten what it was I was objecting to), and one can't wait for rFactor2 for ever.

Quote from Gabkicks :

I. you need to be connected to the internet just to practice on a track alone even.

Not strictly true. Once you've entered a "Test" session i.e. driving on you're own, as opposed to actual "Practice" sessions which occur with other cars, you can then disconnect. Still not very convenient though, to say the least.

Not only that, anyone who re-subscribed with one of the offers, expecting the NTM "on all cars" with version 2.0 has a right to feel misled. Personally, I was suspicious enough to wait.

When it does arrive on any road cars, can some of you with access to the forum keep us filled in on what everyone thinks of it please?

I think it's really bad too. And it's not just momentary, it can go on for a whole straight, even when it's apparently flat to drive on. Which is odd, isn't it?

Yes, and regarding rFactor2: ISI say their 2 man track team has produced 11 new tracks from scratch in 2 years. And these will have bumps and changing surface conditions.

There's an excuse for taking time with the tyre model (no-one really knows how to do it) but I can't see one for nothing else happening.

Quote from tristancliffe :

Indeed.

Go to any track 100 times, and I guarantee that it will effectively be a new track 200 times (once each for qualifying and the race).

iRacing might have 'real' tracks in it, but not one of them captures the track it is intended to be.

I can understand this to an extent, but don't you think you're over-egging that a bit?

There are quite a few pro racers in iRacing who say they use it for learning tracks, it's very useful and nothing else comes close. There are also quite a few regular subscribers who've raced or just done track days in the same car/track combos e.g. Skip at Laguna, VIR and Lime Rock who say the tracks seem spot on and it's a massive advantage. Those who've raced for the first time in RL after iRacing all seem to comment on how familiar it all felt. More so than driving skills themselves - the physics has issues although they often contradict each other about what they are. They are able to point to particular bumps and areas where you tend to come loose in the sim and RL. And you don't get those bump effects in any other sim I've encountered.

That said, some of the fastest guys in GPL, GTR2 and LFS have been immediately fast in iRacing. So if you're fast in any one that's vaguely realistic you'll probably be fast in the others.

But the surface detail makes driving fast on a laser track a different experience - everything else does feel rather like you're hovering because it's too smooth.

And I can say that iRacing tracks all seemed (looked) to me to be quite different after driving allegedly the same tracks in other sims e.g. Brands or Mid Ohio in rFactor. Some of them would definitely get you killed in RL if you thought you knew the shape of the thing and went for it.

Quote from Gabkicks :

yeah it sux, but you'll get used to it after a while. wreckers and idiots get reported and eventually banned if they dont change their ways.

Deliberate and self-incriminating wreckers may well be dealt with - although I've seen examples where even they've still been around after deliberate wrecking.

But in real life there are stewards to deal with general idiocy whereas there's no way for one Nim Cross to moderate that many racers. The result is that idiots are rear ending people almost every race. It's because 4x is no deterrent to these or any general hot head. But they wouldn't carry on like that in real life.

If you're at the front you're less likely to be taken out than in the middle or rear of the pack. Partly because even idiots don't want to be seen taking out a 'name'. Which suggests that a real disincentive might do something - I don't know, say... a 25x penalty for making contact with someone's rear if it damages them. Or if you punt them off or into a spin, you need to be behind them 10 secs later or get flagged to slow down until you are. Then there'd be no advantage to idiocy.

Looking at some fast drivers' high safety rating is misleading - it's not superior skills so much that avoids trouble as there's not much you can do to avoid being rear ended other than drive off the track. Hell, most of the subscribers don't even know the rules for overtaking. Arguments and comments/interpretations in the forum completely at odds with the SC show this. Yet no corrections are provided by iRacing. So what have iRacing done? A video that no one seems to have bothered to watch.

So sure, if you're losing licenses then that suggests you're not doing all you could to avoid trouble. But it's still bloody annoying if you've found time to practice for a big or championship race and a serial idiot just drives straight up your arse or dives and then claims it was your fault. It's only a game, but this is a considerable waste of time and energy and you can't help thinking iRacing are more interested in getting in as many subscribers without be responsible enough about the quality of the experience.

Quote from z-ro 8 :

@Jason:
I assume you're speaking of the spec racer when talking about the braking condition, but that's not iRacing physics, that's the nature of the car.

Let me say, I've quit iRacing after some time. Lots wrong - very uninvolving experience, graphics look like kids TV and sound worse. Basically bored. Anything's more immersive.

But some of the comments here are stupid. I was doing very well in Div1 SRF races a while back using right foot braking. If you're losing it without throttle - which is all but impossible (throttle braking) anyway now without a clutch button, then your brake bias is silly rearward... or you can't drive.

The transmission model is however now rubbish imo - doesn't work without ffb controllers that haven't been invented yet so that's an annoyance having to do things with wrong bad/timing to insure shifts.

SafetyRating is annoying. Some think of it as like money i.e. you get rear ended and you still have to pay the bills in RL. Trouble is, other than for really deliberate psycho behaviour that can be successfully protested to Mr Nim, there's no other real sanction for the offenders. And it doesn't deter adequately.

But again, if you're losing licences over it and can't race a car, then you're part of the problem IMO because lots manage to keep the highest possible safety rating at the highest license (which is harder) and still race a lot.

I'd say I'm waiting for rFactor2. Probably to be disappointed. Dabbling with NetKar2 - which btw, quite a few iRacers think has a better tyre model than iRacing. Dave K's due to release a new physically based model soon though. But LFS seems a lost cause to me due lack of content updates with for no reason and there's plenty of the fastest LFS'ers at iRacing now. (Thought I'd put that in so it didn't get deleted for being OT in the vent thread.)

We understand that the tyre model's difficult. But tracks? There are legions of people knocking out free tracks for other sims all the time. I can tell you some of the LFS'ers over at iRacing - and most of the fastest sim racers seem to be there now - say going back to those glassy smooth LFS tracks holds little appeal.

But even if the theory's correct that it was the laser scanned Rockingham that exposed tyre model problems, they could still knock out something even if it's flat, but just different. Doesn't look good.

The big difference with iRacing is that every other sim is like driving on a flat plate of glass in comparison. So despite all the things to dislike, after feeling the undulations and bumps through the steering and their effects when driving on the limit, you just don't want to bother with anything else.

But I dislike:
-The relative cost but particularly the subscription system.
-The choice of cars
-The sounds ( although they're better than LFS IMO)
-The graphics
-The seriousness and pressure - your real name is there, and every time trial, practice, and race can be watched and downloaded, and is recorded in the stats.
-The PR/hype
-The damage model
-The stupidly slippery grass
-The misleading safety/irating/div rating system
-The overly American racing culture aspect (no offence, but it's just not the same as the British/European one)

But I've done it every day, for the last 6 months and not touched another sim other than maybe a total of 1/2 hr just to remind myself.

I come here periodically hoping for some good news. But that makes no sense; there can be no good news as the tracks will still be flat and dead, unrealistic and like an arcade game no matter how good the physics might turn out to be. FWIW, though, iRacing's Dave K says he's destroyed a lot of tyres (sorry tires) on a test rig investigating the over-the-limit behaviour, and his new tyre model fits the data. Maybe more hype, but we wait expectantly for that update.

On the plus side, if you're fast in LFS, you'll probably be in iRacing too once you've come to terms with the more complex surface.

Thanks for the links ATHome and dekojester. Still not sure how much surface detail there'll be though.

The surface irregularities have a big effect when driving at the limit. iRacing tacks require a lot of extra attention to inputs from steering (small corrections) and throttle to get yourself around. It's a completely different driving experience to the flat tracks in other sims. And you do feel irregularities through the wheel too.

As far as iRacing's tracks' real life accuracy, I couldn't know and don't actually care that much. But a number of people who do have claimed they're spot on.

To save me reading 50 odd pages and possibly still not finding the answer, could some kind person tell me if it's known whether or not Rockingham will have the same level of surface detail (bumps, lumps and contours) as iRacing tracks have?

It's the single thing that puts iRacing in a class of its own IMO.