New tyre behavior when braking

J

J853

Registered
Hi,
I was wondering if something is different with the newer cars (eg. GT3 and Tatuus) because the tyres feel less 'skittish' particularly under braking. A good comparison is the USF2000 vs the new Tatuus USF-17.

With the newer cars it seems to need more pedal pressure (even with the braking at 100% force) to lock the brakes. It feels like you only lock when you are pushing it. This seems more realistic to me (.... having never driven a formula car, my opinion is probably not worth much).

I was wondering if there has been a physics change, or the default setups have been optimised to make this easier? I am really interested in the physics of racing simulators, so am keen to find out the details.
 
There would be no physics change that would do it (base physics I mean), and the 'new model' Bill has linked to above is really quite a small change to the model. It wouldn't cause what you're feeling.

What would, is simply that different cars have different brakes and tyres, so some will lock easier than others. I would say the difference reflects differences between the real cars.
 
Yes, with ABS off and braking power at 100 percent.

I think it may be the difference in tyre model.

The USF 2000 and the usf-17 are pretty similar aren't they?
 
I don't know if you have ever tried the endurance pack (mod version) but before the huge update, I was able to drive all cars with ease. Then they implemented the new tyre model and it just feels like driving on ice, even when breaking.
 
I didn't notice anything like that, but perhaps it could have been something what has changed how brake pedal force is interpreted for different pedals sets. Will pay better attention now. Braking was probably one of the biggest differences to me when coming from AC, in AC it is much more like pedal to the metal thing when braking, in rF2 braking is more subtle. Took me a bit of time to get used to, now I pretty much have and I like it, it is tricky though because what if flatspots got slightlly easier and brake force got more suited to my pedals - it also could make me feel like I learned to deal with it.

But there are people who has been using rF2 for much more years, and has much more hours, and they should know for sure.

By the way, with many cars I often get an idea that acceleration slip ratio is too forgiving, I often think that wheelspin doesn't occur easily enough with many various cars. For example with GT3 cars I can go to lowest TC settings without much thinking, even with low aerodynamics setting, though acceleration slip ratio noticeably increases later with wear, on marbles, on astroturf, in the wet... still somehow not how I "imagined" it would be.
 
Another thing that seems to happen differently on the newer cars is that on some corners you get a strange 'judder' or skipping effect come through the wheel on a couple of corners. This is most obvious on the second the last corner at Adelaide.
 
I can't be for sure, but I tested few older cars (Howston Dissenter and Camaro GT3).

I am under the impression that lockups are similar how they were.

But. I feel like tires does spin up immediately and perfectly as you reduce braking. If I recall it correctly it used to be that if when you lock the tires it wasn't so easy to come back to normal grip so quickly.

Also seems like flatspot FFB effect got reduced a lot, feels like severe flatspot feels now like minimal flatspot used to feel. Which is good because you aren't going to get frustrated and break your desk and servo motor parts, but it is bad because that combining + fast grip up after slide lets you abuse braking. At least to how I remember that it used to be for me.

I just did about 10 over the limit laps at Lime Rock Park with both chicanes with Camaro GT3, everywhere abusing braking, locking tires all the way and so.. It was very fun and very immersive, nothing was annoying me. But then I realised that I am abusing tires like mad, especially under braking, got very minimal flatspot effect, and never failed to slowdown to take turn in point. I used both ABS and TC "conservative".

Acceleration slip feels really right, just as you'd imagine with conservative TC setting, flooring throttle pedal at track like LRP. Braking felt awesome, but at some point it stopped feeling right, because I was just abusing it, locking tires over and over again.

I hope others will contribute to this thread.
 
My main point of comparison is the USF2000 and Skip Barber because I quite enjoy lower power single seaters. The new cars seem to feel a bit more grippy and more like AMS (which has quite a lot of single seaters for comparison).

The new cars feel in particular quite different to something like the Formula C in project cars 2, that is much more 'slidy'.

I race karts but I've never had the opportunity to even drive a single seater, so I don't know what behavior is actually the most realistic. I'm just super curious about the physics of sim racing.
 
Remember the skip barber wasn't some beginner racing car; it was meant to be difficult to drive quickly at low speeds. If you do the wrong thing it will get out of shape, more so than most cars. I doubt that's true of the USF2000 though, so just an aside really.

There can be design choice, for example in modern F1 the drivers initially press the brake pedal as hard as they can when at high speed. With good conditions and the absence of bumps, they simply can't press the pedal hard enough to lock a wheel until they wash off some speed and lose the accompanying downforce. So if you're putting that car in the game, how much brake pressure is 100%? If you allow for a professional driver who does training to allow them to push with a lot of force and do so very consistently, the simulated pressure is quite high but most game players can hit 100% of that force with ease because their pedals don't provide very much resistance (in comparison). So then any suboptimal conditions, or extended braking (as speed drops) will easily lead to lockups.

I would say that would have a bigger influence than any relatively minor physics changes. So maybe those more recent cars simply have a lower force for 100% and that's the difference.

And never ever discount placebo and confirmation bias. People look at those as if they're some sort of weakness, and most people like to think they're immune. We're actually almost always prone to both, and they're fascinating subjects to read up on. Suffice to say that often a difference you think is there isn't, or isn't as stark as you perceive it to be. Again there's no condescension in it, and it's something to always be aware of when checking differences - for example when testing or adjusting setups, when you can trick yourself into believing all sorts of things.
 
Yeah feels like rf2 started considering not only the load cell pedals, and perhaps that's why lockups seems not to be as severe as they were. Flatspots rattling seems a bit too friendly now. Could get terribly annoying and fast in the past.
 
I haven't driven the FISI or the Marussia for a while but I remember those tires being very sensetive to heat and lockups while other tires were less sensetive. Maybe give those cars a spin and check if it really changed.

Tires can be very different in RL too. The last few years you could see Hamilton locking up tires on a regular base because the tires were more forgiving. This year he tries to avoid it at all costs, because Pirelli changed the tread thickness if I am not completely wrong.
 
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