Can someone please explain why the inside rear tyre of the car in the following video skids while cornering relatively hard: http://www.megaupload.com/?d=GSD8SL13
Note that the left rear wheel skids twice in the video: once briefly under braking at the entry to the corner and one long skid under acceleration when exiting the corner.
If its the rear, then its very weird. If you can reproduce this and telemetry (MOTEC works with rFactor I believe) shows the REAR leaving skidmarks, well.. LOL!
rFactor replays are not very 'exact', unlike LFS where all the car dynamics are visible in the replay.
The inside front could well be spinning with an open diff or at least a not very 'tight' diff. rFactor makes this a lot worse than it really is, including the Lupo mod, by using very generous amounts of grip dropoff for a sliding versus a rolling tyre. So inside wheelspin, or lockups under braking, reduce the tyre grip way too much and as such require a lot of letting go of which ever pedal you're on to dial the tyre back into shape.
With rFactor mods you can pretty much also count on some main things like suspensions, car inertias and 'aero' to be dodgy, at the very best.
There also are, or at least seem to be some hard coded things wrong with the tyre physics in rFactor, on which even the best 'mod team' has no influence.
Edit: why ask on the LFS forum?!
LFS has flaws as well. Quite surely something really isn't quite right fundamentally, i.e. regardless of how 'accurate' the data put into the physics, the outcome won't be quite that. It is also not impossible that LFS has a few 'dodgy' variables for its cars, its all too easy to get it a bit wrong. Mostly though, the data that feeds LFS seems quite a bit better, making both fundamentally somewhat flawed but LFS at least scoring solid extra points for trying harder to get it right.
The rear inside wheel is probably lifting off the ground (or at least being seriously unweighted). This would cause it to be spinning at a slower rate than the car speed, which the game could take to mean it should be skidding. Of course, in real life when a FWD cocks its inside rear wheel it doesn't usually cause skidding (perhaps a puff of smoke) when it comes down, but that looks like the case in this replay.
I assume it's only a graphical thing, which rF replays suffer particuarly badly from, if you have the replay play it in slow motion with the chase cam rotated round to see what the rear wheel's doing.
Thanks for the feedback, guys. I've installed the Motec data acquisition plug-in which Niels recommended and used it to have a look at the telemetry for a similar skid also in the Lupo.
As the attached screengrab of the Motec telemetry shows, it's actually the front left which is skidding, not the rear left as I initially supposed looking at the replay.
Assuming that I am reading the telemetry correctly, what appears to be happening is that as the car rolls into the corner, the left side tyres become unloaded. The Lupo is a front-wheel drive car and as I hit the throttle, the relatively unloaded front left spins and slips until it becomes loaded again as the car exits the corner.
edit: Niels, to answer your question about why I posted this here, there are a few reasons. Among them:
- this is where I normally post about all things racing sim related;
- I've been reading this forum long enough to know whose opinions can be trusted at face value;
- history has shown that there is a lot of experience and expertise among the forum members here;
- if I had posted at an rFactor-oriented board, chances are that the thread would have eventually erupted into a flame war.
Yeah agreed.. Though you say 'eventually' regarding the flame war, I'd say it would be a flame war after 2 posts..
I heard the Lupo cars are some fun online. I'd say thats the main thing you might get out of rFactor; a good bit of fun. Car dynamics are just not quite there. I see the front springs of the Lupo are 160.000 N/m which sounds really really stiff! There is only about 250kg of load on each front tyre, perhaps this could get 350 under hard cornering or braking. 100kg is about 1000N so this would cause the suspension to move 6.25 millimeters under the braking or turning. It may peak higher but still you'd have a hard time causing more than 1cm of suspension travel on the front! That is way too stiff. The rear springs of 50.000 are still very 'stiff' considering the cars small weight and the idea that you want the rear suspension to be quite soft. If the real lupos run these wheelrates, I'd be quite surprised, and the drivers would be missing teeth at the end of a race..
But of course, a real lupo racer said it 'rawks' so its an uber mod and anyone who dares critisize will be stoned.. ahhhh the times we live in
