Wazza!

The rFactor rambler is back. I may have discovered a relatively vital thing that is missing in the ISI physics engine. The tyres do not flex laterally, i.e. in the 'sideways' direction when driving.

This lateral movement of the contact patch can easily be a few centimeters and I suppose it would act much like a spring; with more lateral force, the contact patch moves more.

Now the tricky bit; to what does this translate, car handling wise? I found rFactor to not be half bad. Using the inertia values of the LFS FZ50 (thanks Bob.. ) its pretty 'slow' in yaw and easy to control, using better tyre curves and data. However, near going straight, things are quite immediate and snappy. When trying to come out of a left turn sideways, and flick it the other way for a righthander, there is an explosion of body roll and very very fast damper speeds are noticed. This can easily make it snap too much and make you loose control.

Would it help if there was lateral tyre flex? It sounds like it may. When going from a lefthander into a righthander, the tyre contact patches will move in lateral direction, sort of slowing the response (i.e. weight transfer) down a bit. It may just be more forgiving around the centre.

If I'm any sort of correct, that might .. might just be one of the main things that could be improved in the ISI engine!

Any thoughts on the handling influence of lateral tyre flex?

/Niels

try lfs tweak with very tall and very slim sidewalls and see if lfs feels the same with tyres that dont flex (much)

Quote from Niels Heusinkveld :

When trying to come out of a left turn sideways, and flick it the other way for a righthander, there is an explosion of body roll and very very fast damper speeds are noticed. This can easily make it snap too much and make you loose control.

This one of the big problems I always had with ISI sims! It used to drive me insane.

Its not too bad in the 'Vette But you have to be on your toes and time the straightening of the wheel well.

http://www.youtube.com/watch?v=rOVKDgJajFc

Quote from Niels Heusinkveld :

Its not too bad in the 'Vette But you have to be on your toes and time the straightening of the wheel well.

http://www.youtube.com/watch?v=rOVKDgJajFc

are you sure this is an rf vid ? oO
honestly wow im impressed that almost looked convincing

Weird eh! I went from hating ISI to 'seeing possibilities' .. Perhaps when the car is released there might be a little less (ISI)hate in the world..

Looks nice... but I have a hunch it is too easy to drift that car... at least that is how it appears (all ISI games are rather easy to drive on the limit). I posted a comment though... I request an onboard vid

Atleast the driver in the car looks real It looked like a real person, i got scared Nice work.

Sorry for going off-topic but the sound of that car is ****ing amazing. And it actually looks real, one of the only times i see potential in an rfactor mod (1994 F1 mod looks amazing although ive yet to try it, and FBMW is pretty spot on, most others are fairly poor and use just ridiculous tyre curves).

Quote from Niels Heusinkveld :

This lateral movement of the contact patch can easily be a few centimeters and I suppose it would act much like a spring; with more lateral force, the contact patch moves more.

I'd expect it to behave like a spring+damper. The role of the air inside the tire is limited (since it's not compressed much by sideways tire flex), so most of the behaviour comes from the sidewall. Rubber has a significant amount of internal damping. This could make the tire more forgiving, because the response to fast load changes is damped.

OTOH, race tires have stiffer sidewalls than street tires -- possibly because less tire flex makes the car more responsive and gives the driver a better 'feel' of the car. But in simracing you get less feedback than IRL and you get it later, so a more forgiving tire may be helpful to keep the car under control.

Quote from DeKo :

Sorry for going off-topic but the sound of that car is ****ing amazing. And it actually looks real, one of the only times i see potential in an rfactor mod (1994 F1 mod looks amazing although ive yet to try it, and FBMW is pretty spot on, most others are fairly poor and use just ridiculous tyre curves).

amazing ? It sounded like a tractor. I don't remember a C6 sounding like this...

I used that FBMW mod when I was 'learning' Castle Combe, and the physics are absolutely awful! They feel more like driving Scaletrix underwater than a real car. LFS 0.04 was better, and that was about 5 years ago!

Quote from wsinda :

Rubber has a significant amount of internal damping.

that appears to be largely lacking in lfs atm so i dont think it has anything to do with the handling issues if you compare lfs with rf

Depends, tyres in LFS seem damped enough in the vertical direction. I'm not sure about laterally though.

select mouse steering with a very high sensitivity and wiggle the wheel while standing still ... the effect of it seems dodgy to me

Now repeat the same in a real car... oh wait, you can't
No seriously, what seems dodgy to you? I mean, does it wiggle too long?

Quote from AndroidXP :

Now repeat the same in a real car... oh wait, you can't

same thing happens if you come to a standstill after a 90° slide
also you can achieve the same effect if you push against the wheels with your foot on a real car

Quote :

No seriously, what seems dodgy to you? I mean, does it wiggle too long?

it wiggles too much and too long imho ... the oscillation appears to be nigh on undamped
actually the fact that is oscillates at all ... what id expect is a slight overshot at worst but not ~1sec of oscillations that slowly die down

Quote from DeKo :

and FBMW is pretty spot on,

Either the FBMW mod has changed a lot since I last tried it or we have very different ideas on how a single seater should behave, it also IIRC had no dashboard instrumentation other than little rev LEDs.

http://www.youtube.com/watch?v=AM3uiUQlh4c

this is a normal driving onboard thingy with monotone voice comments..

Quote from tristancliffe :

I used that FBMW mod when I was 'learning' Castle Combe, and the physics are absolutely awful! They feel more like driving Scaletrix underwater than a real car. LFS 0.04 was better, and that was about 5 years ago!

This is how I felt about Rtracktor when bought it couple it with the over 10 gig of mods available and virtually all the servers passworded I won't play it.


Mod looks promising =) I would try this mod out. Looks fun! It's possible that Rfactor could become better in their physics with lateral tire flex modeled. But I have a feeling it would take more than just that, but it would help.