I think a big issue with pacejka and getting tyres right is the compromise you need to put in there to make the mixing/combining of forces do what you want them to do.
Pacejka89/94.96 or whatever we have here are generally designed for steady state or slightly over the limits.
That means data can be fairly ok for doing braking and accelerating tasks, and cornering etc... but as soon as you get things wrong when driving and get some big slip angles, counter-steer, try drift, or whatever else, then they can react oddly.
In my experience the original Alpine data for the 225/45 R17 was like a genesis moment for us in Racer. Suddenly cars felt like they were driving on rubber patches not just wooden blocks scraping along tarmac!
So we can learn a lot from that data in my view, for road cars at least.
But for me I generated a nice excel sheet and just started making factors to give certain values from input dimensions such as profile, patch aspect, soft > hard compound, and generally that gave ok ish results.
I pretty much did a0...5 and b0...5 then kept most of the C coeffs the same as that hallowed 225/45 R17 data
But even now I often find myself tuning tyres iteratively and ignoring what appears sensible. Just play with values in the player.
My current tyres on a road car I'm working on are just the result of hours and hours of testing and tweaking and trying new things out and slowly erring towards a behaviour I like the feel of.
As said, a key issue is post limit behaviour for us, so often we might make wrong choices for a specific case so that post-limit mixing is better.
Ie, I can get a really good near limit behaviour that is horrible over the limit and totally unusable for racing... then you can get really nice over the limit pacejka mixing but the under the limit curves are no good (ie, tyres are almost impossible to spin up in a straight line with 400bhp to rear wheels)
This is something I'd hoped the MF5.2 pacejka would fix as it includes mixing coefficients but in my experience with it thus far it's not so great... even with very sensible curves the behaviour is very odd.
I have a feeling the implementation is wrong but only really Ruud can check that out to be sure.
Just from my perspective, I spent many hours (probably hundreds) in pacejka player back in 2002/2003 ish and learnt oodles about tyres, and also learnt that in the end it all comes down to in-sim results and what you want.
Do you want a tyre that is fun to drive with a realistic response, or ultimate realism (probably not desirable considering Racer is far from a 'complete' sim with it's tyre patch modelling limitations, no bushing simulations, linear suspension kinematics etc etc), or just fun and a bit arcade?
With the E39 BMW M5 ini I made back in the day I spent literally days at the Ring tweaking one coefficient at a time, getting the behaviour I felt was right... same with the BMW M3...
Tweak with the pacejka player, read lots on real tyres, look at real pacejka, THEN do lots of in-sim testing to understand how the values change things, THEN forget it all and use the experience to allow you to make the tyre YOU want... as that is all that really matters in the end
Usually the most 'real' data doesn't work the way you want it to for the specific application you have. Ie, I got real data for my exact tyre on my car, same dimensions, brand, load rating, everything, and it was a driving sim abortion worse than anything that had gone before
Dave
Pacejka89/94.96 or whatever we have here are generally designed for steady state or slightly over the limits.
That means data can be fairly ok for doing braking and accelerating tasks, and cornering etc... but as soon as you get things wrong when driving and get some big slip angles, counter-steer, try drift, or whatever else, then they can react oddly.
In my experience the original Alpine data for the 225/45 R17 was like a genesis moment for us in Racer. Suddenly cars felt like they were driving on rubber patches not just wooden blocks scraping along tarmac!
So we can learn a lot from that data in my view, for road cars at least.
But for me I generated a nice excel sheet and just started making factors to give certain values from input dimensions such as profile, patch aspect, soft > hard compound, and generally that gave ok ish results.
I pretty much did a0...5 and b0...5 then kept most of the C coeffs the same as that hallowed 225/45 R17 data
But even now I often find myself tuning tyres iteratively and ignoring what appears sensible. Just play with values in the player.
My current tyres on a road car I'm working on are just the result of hours and hours of testing and tweaking and trying new things out and slowly erring towards a behaviour I like the feel of.
As said, a key issue is post limit behaviour for us, so often we might make wrong choices for a specific case so that post-limit mixing is better.
Ie, I can get a really good near limit behaviour that is horrible over the limit and totally unusable for racing... then you can get really nice over the limit pacejka mixing but the under the limit curves are no good (ie, tyres are almost impossible to spin up in a straight line with 400bhp to rear wheels)
This is something I'd hoped the MF5.2 pacejka would fix as it includes mixing coefficients but in my experience with it thus far it's not so great... even with very sensible curves the behaviour is very odd.
I have a feeling the implementation is wrong but only really Ruud can check that out to be sure.
Just from my perspective, I spent many hours (probably hundreds) in pacejka player back in 2002/2003 ish and learnt oodles about tyres, and also learnt that in the end it all comes down to in-sim results and what you want.
Do you want a tyre that is fun to drive with a realistic response, or ultimate realism (probably not desirable considering Racer is far from a 'complete' sim with it's tyre patch modelling limitations, no bushing simulations, linear suspension kinematics etc etc), or just fun and a bit arcade?
With the E39 BMW M5 ini I made back in the day I spent literally days at the Ring tweaking one coefficient at a time, getting the behaviour I felt was right... same with the BMW M3...
Tweak with the pacejka player, read lots on real tyres, look at real pacejka, THEN do lots of in-sim testing to understand how the values change things, THEN forget it all and use the experience to allow you to make the tyre YOU want... as that is all that really matters in the end
Usually the most 'real' data doesn't work the way you want it to for the specific application you have. Ie, I got real data for my exact tyre on my car, same dimensions, brand, load rating, everything, and it was a driving sim abortion worse than anything that had gone before
Dave
