The online racing simulator
iRacing - chapter III
(1142 posts, started )
#901 - CSF
Wow looks like it will be a nice upgrade tyre physics wise, looking forward to seeing how tyre derogation plays out over race distances
do they simulate tire flex yet?
Quote from CodeLyoko1 :do they simulate tire flex yet?

I'm certain tyre flex has been modeled from very early on it just hasn't been represented graphically - I'm sure your just trolling though :P.

Latest release talks about "- The tire model has an improved solver to find the amount of tread yaw under dynamic conditions (i.e. non-equilibrium). This has significantly improved transient behavior and tire response to changing loads."
which has the potential to change the feel a lot.

So if tread yaw is being modeled tyre flex would be pretty simple in comparison..
If you can prove me they do simulate it, please prove me wrong. But every direction I ask and search, there it either says it doesn't simulate it or there is nothing about it that it does.
Quote from CodeLyoko1 :If you can prove me they do simulate it, please prove me wrong. But every direction I ask and search, there it either says it doesn't simulate it or there is nothing about it that it does.

I quote Todd from a thread in iRacing forum post date 8/12/2011, Todd is well respected and considered well versed in the subject in question both here and there.

Quote from Todd Wasson :All tire models use deformation to produce the forces if they use slip angle, slip ratio, and vertical compression as input. Rendering it graphically is another thing. The deformations in the animation may come to some extent, or totally from the tire model that produces the forces in the physics model, or they may not.

Either way, it's enough to fool the masses as evidenced by this thread

Another quote from Eric in this thread in which Todd also engaged in discussion at length "Goodyear NASCAR Tire InformationTechnical Inspection In"
http://members.iracing.com/jforum/posts/list/1856652.page

Quote from Eric Hudec :As I've said before the difference between a competition tire and street tires is it's carcass construction, including tread construction effects (plys, belts, aspect ratios, section widths, contact surface radii of curvature, thread depth, thread void area, tread width, etc.). Typically racing tires are much more mechanically stiff than street tires, so therefore the knee will happen earlier for similar load and inflation pressure cases compared to a street tire.

and another

Quote from Eric Hudec :It depends on the Kyaw of the tire in the particular set of input parameters on track. So I can't really answer with specifics without knowing the tire, or the condition in which it operates. The amount of shearing of the thread relative to the wheel, for a giving slip angle on a given tire, will depend paramountly on inflation pressure and vertical load - simplified to contact pressure (Fz/psi = lb/lb/in^2 = in^2) as well as the instantaneous yaw stiffness.

I think you can pretty easily ascertain that tyre flex is modeled in detail in iRacing and that is just from a 5 min search of forums so now doubt there is more on the subject.
Fair enough. Does bring back the question to me why it feels like your tires are so solid, or as JR said "glass tires". Is it really all because of the FFB? Or is there something else?
If the tires didnt flex what would be the point in airpressures?
Quote from Mustangman759 :If the tires didnt flex what would be the point in airpressures?

you can fake that reaction pretty easily (from their perspective)
Quote from CodeLyoko1 :you can fake that reaction pretty easily (from their perspective)

So instead of trying to mathematically solve things you have no sight on, how about getting to race or may even get a proper wheel to transmit the FFB from iRacing? The tires feel pretty neat finally and they aren't just lego blocks under your car that have some grip.
Quote from Kristi :So instead of trying to mathematically solve things you have no sight on, how about getting to race or may even get a proper wheel to transmit the FFB from iRacing? The tires feel pretty neat finally and they aren't just lego blocks under your car that have some grip.

I am not trying to solve things here. I'm just interested in how and why.

Is a DFGT really not good enough for iracing? I have no problems in any other simulator.

IF I have my GPU back before my iracing runs out, I'll give the new tire model a shot. Didn't have the chance yet. Otherwise I have other ways to test it :P
How do you define good enough? Countless championships in sim racing have been won with far inferior wheels than dfgt. For sim racing if you want sheer speed basically every wheel you can buy nowadays is good enough. But for realism you probably "need" a servomotor wheel like simsteering or accuforce wheels.
Quote from Hyperactive :How do you define good enough? Countless championships in sim racing have been won with far inferior wheels than dfgt. For sim racing if you want sheer speed basically every wheel you can buy nowadays is good enough. But for realism you probably "need" a servomotor wheel like simsteering or accuforce wheels.

with good enough, I mean a steering wheel where I can feel the car enough, that the tires don't feel a solid piece of concrete.
Promo code for inactive subs, PR-ComeBack5 for 3-months, $5.
Quote from CodeLyoko1 :with good enough, I mean a steering wheel where I can feel the car enough, that the tires don't feel a solid piece of concrete.

DFGT is fine. I've never had a problem with feeling the car in iRacing with it. The only bad thing about a DFGT is the pedals, the wheel itself is good. In iRacing you need a better feel on the brake pedal and can't just go 100% brake like you can in some other sims, that's the only reason I can think of you might struggle with a DFGT but I personally never had a problem
Quote from IsaacPrice :In iRacing you need a better feel on the brake pedal and can't just go 100% brake like you can in some other sims, that's the only reason I can think of you might struggle with a DFGT but I personally never had a problem

Exactly a point I mentioned in the General Discussion topic and how load-cell pedals act in LFS compared to other sims. Basically, you might say having a loadcell pedal in iRacing if you compete in a non-ABS car is heaven and hell.

I never had a DFGT, but I had a G25. It was enough to feel the car nicely around the track, and gave pretty nice inputs from the tires to not feel like I'm driving a LEGO car. I thought that was perfect. Then I got a CSW and it's not only a single step forward in FFB feel. But that's to be said in rF2, AC and basically anywhere except for LFS, which is weird.
... and I'm just sitting here with a bloody old momo with a loose worn axis, getting NO feeling through the wheel at all. Not to talk about the crap pedals that have almost no resistance and the throttle axis is cut at least 50%.
Quote from Töki (HUN) :... and I'm just sitting here with a bloody old momo with a loose worn axis, getting NO feeling through the wheel at all. Not to talk about the crap pedals that have almost no resistance and the throttle axis is cut at least 50%.

I know the feeling about the loose axis. You turn into a corner and then go to unturn and the car keeps turning by itself lol. Without FFB it's a bit better, but not much. Glad I got rid of that wheel
Thanks Toki (for the promo code), i guess i just came back to iR.
And i just bought a cockpit for my G27, things gonna get fun...
Quote from Töki (HUN) :Promo code for inactive subs, PR-ComeBack5 for 3-months, $5.

Stupid question.. If my sub ends in 26. day, can I just buy 3 months with that code? Or do I have to be inactive for longer time?
Quote from CardsetCrazy :Stupid question.. If my sub ends in 26. day, can I just buy 3 months with that code? Or do I have to be inactive for longer time?

My sub expired on the 12th, so I think you'll be fine.
crap I registered right before that :\


iRacing - chapter III
(1142 posts, started )
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