Quote from Tuze :

I don't understand how they could go so long with this tire model / physics.

Well, doing a realistic tire simulation took 2 years of work of the best sim programmer in the world, and nobody else had attempted such a task in more than 20 years of "sim racing" games. Why didn't you program a tire model and offered it to iRacing?

Thanks DeKo. It must be recognized that iRacing is being really professional in this release.

Hi, iRacingBits has just tweeted that an update has just been posted about the New Tire Model (warning: it's not ready yet.) Can someone with an active account paste here the announcement? Url should be this http://t.co/ajtH6jO

Quote from PMD9409 :

Quote :

I know everyone is eagerly awaiting the new Nationwide car and we are eager to get it out to you. Unfortunately it does not appear it will be out this week. We are doing everything in our power to get this out to you ASAP.

I have seen a number of posts about just having us release the car as it is. Unfortunately this is not realistic as a tiny fraction of our members actually come to the forums or read the release notes to understand what we are releasing. Therefore we need to make the car perform as close to flawlessly as we can before we release it.

A piece of good news for you is that we plan on releasing ATLAS tomorrow.

We apologize for the inconvenience and appreciate your patience.

Steve

http://members.iracing.com/jforum/posts/list/1476772.page

Thank you for the update, ineX P.Diaz. My account has been inactive for a while but I'm really interested into new tire model news.

Quote from Hyperactive :

Quote from codehound :

With respect to low slip angle and low speed grip, if someone leans against a stationary car, it doesn't slide off the road, even though there is no slip angle. The resistance force is based on the sidewall defection, not slip angle. I would guess that at most speeds there is a corelation between sidewall flex and slip angle and it is easier to work with slip angle curves. But this seems to break down at lower speeds. (GPL uses 6 m/s as a cutoff to switch to a different method.) netKar Pro had problems with cars "gliding" when supposedly stopped.

But that is totally separate issue. About every sim ever has had that same problem. Iracing has it, lfs had it and so forth. Apparently the problem is that when the car is stationary it is hard to keep it in place.

And iRacing New Tire Model seems to have the same problems as well. In the update Tony Gardner posted last wednesday, he said that the last bug that remains before the new Impala Nationwide car is released is that, when parked "there is a little shaking or minor instability."

I though this problem was only typical of the pacejka formula, which doesn't work for low speeds since velocity appears as denominator. From Kaemmer's explanation video on last october ("Dave Kaemmer iRacing Tire Model Discussion" on vimeo), it seems they are using a "brush model" instead of pacejka, but still appear to have the same zero-speed issue.

Last edited by carfetish, Sat 14 May 2011, 19:37.