Physics discussion thread

Glad to hear you have made a clear arguments and examples. Also now I see I'm not alone with it.
I have not tried extreme settings, because believe if only extreme settings can fix it, it is not a best solution or outcome.

 

TBF, you also don't now the setups of the onboard videos you watched. Their diffs could've been setup more aggressively. Real world setups changes can also have a massive effect on how a car behaves. So to say is was only 100rpm increase IRL, are only for those cars with the setups they were running when those videos were taken. I guarantee you, if it was a Miata with an open diff and OEM rear swaybar going over that section, the rpm jump would easily have been upwards of 500rpm.

 

You cant tune it out. You can reduce it by running 450 Nm preload on a GT3. At 250 Nm inside wheel spin reduces just by few rotation/s compared to 120Nm. To me 450 Nm isn't reasonable value. And again, it can't be tuned out in a car that doesn't expose power ramp angle. It's possible for car with adjustable power ramp angle to achieve acceptable results. From that could take it two ways - (1) the power ramp angle that's underneath is bad/wrong. Or (2) if the developer, or whoever, assumes power ramp angle is good in these cars, then maybe possible physics issue?
And yet, I can't explain the wheelspin/RPM spike when just driving straight over mountain straight crest, which has nothing to do with diff (simply driving over crest even triggering TC. You can connect both together, this tire slip is possibly why TC is so intrusive in AMS2). And as much as people despise comparing other sims here, ACC or LMU have represented this aspect more authentically. Personally, I believe this is something that shouldn't even be tuned for, this should't happen in a GT3 full stop, no matter the setup. And its not just GT3s.

And yet, I didn't compare miata to gt3 or aussie supercar to lmp2, but GT3 onboards to GT3s. Audi to audi, pork to pork, amg to amg. All produce same results. What so if I don't know what setup they run? I have the luxury to press escape, go to garage, edit setup and go again and again and again in effort to achieve my goal or, in this case, achieve authentic behavior to that of onboards I looked in to. Which means going through many different setup configuration, which I did. .

 

Maybe i misunderstood your earlier comment about being able to reduce it ??

Either way it’s not a big concern of the physics .
Regardless of car , (as it occurs in many & i’m not focusing on Gt3 or anything particular. ) the expected result of a unloaded wheel that’s lost full contact with the track spinning up a little under full torque is sound in my opinion and matches my experience.

I instinctively control this by ever so slightly relaxing the throttle over the crest as that removes the peak torque from the situation, and real world drivers would do this too.
Using full throttle isn’t always going to be possible depending on the car and its grip levels.

I think springs and dampers set up would have a more significant impact on reducing this than anything diff related ( it’s not a diff issue imo) .

Overall if this is the levels of nit pick we are at with Ams2 Physics, then we are in a good place .
But it’s important to separate physics from individual car modelling and set up.
Is the behaviour correct for the scenario or is the behaviour correct for the individual car are different things .

 

Not disagreeing about wheel spinning when lost full contact, I also don't notice anything bad there. But the tire/s never get off the ground. Again, I have checked tire height above ground channel in Motec over hundreds of laps. They do not go airborne, only gets unloaded. So I don't see your point relevant here.
Think about the video posted before that started all this? Did smoke from his wheel come from spinning in air?

Sure, driver inputs matter. But not sure I should be lifting in middle of 1km straight over a crest to have authentic car behavior from IRL onboards where they have 100% throttle. Same with the cutting, on mid-late apex you are already on 100% throttle in a GT3, not a lot of throttle modulation.

I was also thinking that, if not more significant, than at least some impact. After multiple days, haven't found the results I am looking for. Downforce and power ramp angle are the most significant. But in GT3, and other classes with not exposed ramp angle settings, your hands are tied. For example, running around 35-40 degree power ramp angle in GT1(2005) will eliminate inside wheel from spinning at cutting.

Yes, I have no idea what is the cause. Is it longitudinal tire slip, do cars get too "light" over crests? I don't know. Not the one who wrote the physics, I didn't model the cars etc. etc. I can only observe and guess.

Maybe, maybe not. I can only speculate, but this is why TC in AMS2 is so intrusive all the time. I think they are intertwined and play a part on how the car drives. How big is the impact? I don't know.

In closure. I will rest my case here. My experience is that GT3 should not spin up inside wheel in cutting or spinning wheels over light crest by minimum 4x as much as IRL or other sims, and I find it not authentic. Currently can't find a reason to change my mind on this. Others might see it is true to life, that's fine. Maybe I am completely wrong, time will tell.

 

Just to clarify, I never said the wheel was in the Air , just that it wasn’t in full contact ( could have picked a better term ) as in , it’s become unloaded to the point it doesn’t have a enough downward force and friction to resist slipping.

We are allowed to disagree, it perfectly normal. I think we would all agree as do the devs that TC is not as accurately modelled as they would like , and it’s currently behaving more like a simpler road car system that allows a certain amount of slip rather than a sophisticated racing system.
so driver input control is somewhat still important to avoid wheel spin .

 

I need help understanding this.

I ran the gen 2 AMG GT3. Maxed out soft front ARB, max stiffness rear ARB. No rear downforce.

The car is extremely pointy but i can not get any snap oversteer, the rear seems glued to the ground. If you look at the video i think the car behavior looks really weird how the front grips, the rear never snaps so it just drifts on all 4 wheels.

https://youtube.com/shorts/ERR4vbBxmFI?is=eRoqqHDdwkOKYYNZ

Would love some feedback here.

 

Tried it out of curiosity. And the overwhelming impression I got was it has high speed understeer, and the fronts start to slide before the rear . if you take the corner at a lower, more sensible speed, the front still does what it needs and the rear can come around.

 

i mean softer arb front and high downforce in the front really pushes the fronts down. Thats all good.
Its the rear that just stays glued no matter what, now a lot of cars would lose grip from such an aggressive setup but the AMG gt3 can’t it seems like.

 

ARB adjustment is quite limited, and they almost end up even with just a small bias to stiffness of rear . 60nm Front 70nm rear , So it’s quite neutral really .
it’s got less front grip than the default set up,
Front just sledges and the faster you go the more it sledges . I would not describe it as having a pointy front at all.
But it doesn’t seem to suffer as much as you would imagine from having low downforce, at these speeds anyway , but there won’t be no rear downforce, there’s still a large apparatus on the boot, and a diffuser .

 

The AMG has mid-front engine placement, which would mean less mass in the rear trying to go in the direction of the tangent, right?

 

Hi guys.
Disclaimer: no holywar was ment. I just curious, because maybe have some wrong settings

Topic is about rain weather and rain VS slick tires grip.
Porsche N-GN, Nord. Rain weather, default progression surface, no helpers

What I see that in obviously raine and wet weather (visually) with decent rain I can press throttle with minimum slides and go 170 kmh through the high speed corners, while on wet tires that ment to be more grippy in wet not causing aquaplaning etc , when I press acceleration the car rear starting to dance and slides much more than on slick tires. In heavy rain, wet surface settings I also noticed, that you can go on slicks with comfort feelings (but already slower then on wet tires) . In compare, GT7, iracing, and in real life what I also randomly do, on wet track sport tires are almos useless and even dangerous.

Why ?

 

on AMS2 if you have enough temperature on the slicks, you tend to get plenty of grip even if the track is wet and as long you can keep those up to temp, you usually go faster on slicks.

IMO there is room for improvement here still

 

The R25 and R26 cars, besides needing traction control to prevent wheel spin, also both lack engine power. The R25 reached a top speed of 360 km/h in qualifying without a slipstream (its aerodynamics weren't optimal), while in Automobilista 2 it only managed 345 km/h. The same is true for the R26, which should be capable of reaching 345 km/h at Monza but only manages 335 km/h.

 

How do you come to the conclusion that its horsepower is too low?
Did you check the overlay if the horsepower output is correct?

Did you adjust the setup to maximize top speed?

 

I saw a video where someone set the spoiler to its minimum (which isn't actually the case) and the R25 doesn't go over 348-350 km/h, when it should easily exceed 360 km/h. And the R26 seems to have 720 hp off the line, when it should be around 740. Anyway, I don't care about the horsepower; the top speed is far too low. Clearly, something isn't properly tuned. The traction control is the same; it spins a lot even when it's on. This isn't realistic. However, the inertia and cornering seem excellent. It frustrates me that it doesn't have the traction control system that these cars have.