Pacejka 96 model Fx

[Silente]

Hi,

I was looking to TTC Stackpole data and i found that Pacejka 96 model doesn't take into account camber in longitudinal forces calculations.

Is that true or i am missing something?

Thanks

[Paul Hugon]

It's true you are not missing something! I think only Pacejka 5.3 take camber into account in longitudinal.

[Silente]

This is really a bad bad news! What a delusion!

Thanks for your help

[Tim.Wright]

Since I left university, practically all of the tyre data I have seen has had the camber modifying coeeficients for Fx set to zero.

I have trouble believing it has no influence. Especially on the wide tyres.

[exFSAE]

Originally posted by Timo:
Since I left university, practically all of the tyre data I have seen has had the camber modifying coeeficients for Fx set to zero.

I have trouble believing it has no influence. Especially on the wide tyres.

Sounds like its time to get better tire data http://fsae.com/groupee_common/emoticons/icon_smile.gif

Or fit the raw data yourself.

[Tim.Wright]

Yes well if only it was that easy.

Anyway, I mentioned this because I have seen it often and thought there might be a reason for it. Its not my job to be fitting curves to data I dont have but thats beside the point.

For FSAE you are lucky enough to have the raw data as well as the curves, so you can actually check the tests and see exactly what the influence of camber is on Fx

Tim

[Silente]

anyway nearly all the data of TTC are about cross ply tires.

Out of FSAE nearly all the racing tires are radial.

I will enjoy to have a look on michelin data (michelin are radials) to see how grip is influenced by camber. On other tires i have analyzed, the camber doesn't influence grip dramatically, but it actually changes the picture...

Why nobody has ever implemented camber in longitudinal models? Or it has been added in pacejka >96?

[Jersey Tom]

Originally posted by Silente:
anyway nearly all the data of TTC are about cross ply tires.

Out of FSAE nearly all the racing tires are radial.

Not entirely that simple.

[Edward M. Kasprzak]

The TTC tests include Fx at 0, 2 and 4 deg. inclination angles. I don't know what is or isn't in the Stackpole Pacejka models, but the MRA (Milliken) models include the inclination angle effect.

Keep in mind that the MRA models donated to the TTC are a subset of MRA's full tire modeling capability. Stackpole may do the same, so they may be able to include the inclination angle effect even if they haven't provided it to TTC members.

[BillCobb]

The Stackpole Pacejka coefficients and equations are clearly listed on the Round 3 CD in a .PDF file.

Parameter PCx1 et al are the camber sensitivities and quite a few are non zero, Some have actually been altered by the fit optimization program away from their inital stating values of 1.300000 or 1.700000.

BTW: Not all racing tires are radials, even if they are labeled Racing Radials, taking one apart will reveal the truth about that statement. Close, but NO cigar. Just wear one out to the cords, cut thru it and you will find a new slant on this little known fact.

[flavorPacket]

Originally posted by BillCobb:
Just wear one out to the cords, cut thru it and you will find a new slant on this little known fact.

Choked on my Red Bull reading that one, Bill

[BillCobb]

Hope you didn't spill any. Recall that I buy Red Bull by the case at Costco. That's a case per week for both of us. Leaded for me, unleaded for the S.O. .