Physic discussion thread

I don't disagree that there is probably room for improvement and the lack of forward burnouts being a symptom of something with the C3. But it will always spin the tires a lot more going reverse, because of what azaris said. And it probably doesn't matter that much if the track is green or well rubbered when you do that, because the more it accelerates in reverse, the less it will grip due to the driven wheels unloading.

It's the opposite when launching an RWD forwards. Load increases and (depending on the tire) turns to more grip. The rear squats which softens weight transfer and keeps increased load on the rears for longer and smoother. This does mean a lot of grip, but even so it's suspiciously grippy in your situation I agree. I won't even guess what it is, cause it could also be the driveline eating away that initial breakaway torque. So rather than engine inertia being sent to the rear tires, it's lost in clutch slip and other driveline losses... Or any number of other things together.

It's easier to overwhelm even grippier tires when turning. And it would also depend on the tire type. Road tires just can't multitask all that well compared to slicks.

I've been playing around in BeamNG a lot and sometimes a few percent more or less something can make a major difference. And yes rubbered drag strips are far better for launching . It's certainly not a perfect sim, but it is physical and cars are very configurable on the fly.

 

Agree totally. The behavior in terms of breaking traction from standstill is suspicious in several cars IMHO. That however tells almost nothing about the capability to lose traction when actually racing them because what's doing the job there isn't the engine power but the total grip being saturated by the lateral grip: in that case it only takes very little power to gain significant lateral slippage which makes almost irrelevant all the experiments we are doing.
And by the way, rather than tires grip itself there could be another million different reasons for the standstill lack of bite as @oez was saying

 

It seems to me sometimes it's unusually hard to lose traction and spin out on corner exit. I dont know if that's been fixed as I've not played AMS2 much in a while, but I do feel like sometimes in the ultra high power cars, at low speeds, even if you can spin the rear tires, it's really difficult to "loop" the car. Something about it seems to ring a bit untrue, but it could just be accurate.

 

It has always been "easy" if you apply some "Drift Show" settings like high camber and low toe and closed Differentials, but those setups usually used for "Drift Sports" make the cars basically unraceable on most tracks. In the past, the overall high track temperatures also provides a lot of grip. Most of that is solved in lates version of AMS2, and now even the M1 Procar is able to lose grip in the rear.

 

Which car are we talking about? Again the 720S? Some aero cars with max rear wing by default?

 

The higher power cars tend to be very high downforce cars, but everything from the Formula Vintage to Group C to the Formula Classic Gen 2's and so on. Yeah, some of these are very high downforce cars, but you dont have massive downforce at very low speeds. Even in the F-Vintage cars I dont think I've ever gotten anywhere close to something like this:

Maybe I'm just a good driver. Maybe it's the diffs pushing the cars straight all the time. Maybe it's the fact that most of the cars I race in AMS2 use racing slicks and they are just going to behave differently.

I know the way the forums have gone lately, it's not very popular to say anything critical of AMS2 or Reiza, but it's more of me just seeing if anyone else has felt anything similar. I'm not necessarily saying it's wrong, just that I wonder if it is.

 

That is a very interesting spin. Is the the track actually damp? Seems like a fairly benign place to lose it otherwise. The car in front also slides around so maybe the track was slippery for some reason. I agree that looks more like Grand Prix Legends or rFactor 1 territory.

 

i personally have no problems getting sideways on throttle in just about every car in the game. and the high powered ones are damn hard to control because of this.
which is part of the fun and sometimes frustrating too.
I have to be very deliberate with the throttle. so can’t really see why others don’t experience the same things.
it’s like some users have a different version ?

 

I believe this one was solved by not having broken tires that have episodes of sharp lateral grip leading to the inside tire lifting after you "kick the rear out". But I'm not certain.

Just interesting whenever there's a fix that doesn't fit a definitive statement like "it must be the diff code" (a favorite of mine early this year).

Though somewhat related to that there were also default diff setting changes to GT3 cars at least, because they were very open - fit for the old much more stubborn driveline. Just mentioning that to not sound black and white .

What's that mention of hitting the bank on the video? I was wondering if he hit the sidewalk curb and got thrown into a low speed spin.

 

No, the rear kicks out all the time. The problem is that the car never feels as if it is going to spin out. It actually feels like it's impossible to spin out. I spent some time in the VRC Indy Car mod for rFactor 2 last night, and you had to be very delicate on the throttle due to the turbo lag and power those cars have. The power will suddenly hit a hard peak, and then the car just spins. The very powerful open wheel cars in iRacing have the same tendencies, if you get too aggressive on corner exit with the throttle, it will spin out on you. I've spun out the iR-01, Lotus 79, and the FR3.5 repeatedly trying to get out of some corners. I usually struggle with it a little on every new circuit I learn with any of those.

I dont think I've EVER spun out on throttle in AMS2 in any car. I've gotten a good power slide/drift on exit in almost every high power car. But they never seem to spin. This is what I find odd.

Im specifically referring to a few particular instances that I thought were quite unwarranted. Probably the one that most comes to mind was where I was accused of cheating on the TT Boards because I was using the brakes to try to get the F-Retros to rotate, because they usually seem pretty understeery. And then another instance where I hopped into my league's race server and tried the Lotus 72 after a big update, and no matter what I tried I couldn't get any heat into the tires, the tire temps just stayed way too low and the car was pretty much undriveable, even after 5-10 laps. I even started a race (Which obviously starts with the tires warm) and within 4-5 laps the front tires were back to being incredibly cold and undriveable again. Everyone told me it was user error and I didnt know what I was doing, for something that was pretty simple to test. I had the same problem with the Lotus 79, but not as badly. Meanwhile these cars didnt have this problem prior to that update.

There are many aspects to this that are difficult to understand and hard to measure empirically, my underlying feeling that there is something weird about how cars never seem to spin in AMS2 (they will slide, sure, but it's difficult to spin them) is much harder to quantify than other issues.

 

Well the other thing that I've considered, is it's possible AMS2 is just closer to reality, so it's easier to "feel"/predict what the car is going to do than the other games because it's just more natural. I definitely dont think iRacing is the peak of driving sim physics.

 

Billy Strange actually commented more than a year ago about how many sims get the low-speed throttle sensitivity wrong and AMS2 still had similar tendencies back then:

If you try the V10G1 now it's almost night and day to what it once was, so yes the low speed spins clearly have been toned down. But if a former dirt sprint car (700+ hp) driver thinks sims exaggerate the wheel spin at low speeds...

 

Did the diffs ever get solved or are they just getting incrementally improved? I know back when the geared diff was available for the F-Retros back when Hockenheim first came out, those cars felt absolutely incredible with that diff. I know how good AMS2 can be because that was an option once.

 

According to Reiza and earlier conversations in the forum the diff per se wasn't faulty. What solved it almost completely was adjusting other mechanical bits and pieces properties that were in the surroundings and having an impact on the inputs to the diff: roller bearings resistence and inertia, engine shaft and other engine components inertias and with v1.2 also some adjustments to CoG and tire treads that changed significantly physics.
It appears like there weren't any "wrong" calculations performed by the diff routine itself rather tuning of the physical properties of surrounding items sorted it.

 

I wonder if something like the diff problem also happens with visual car rotation. Has this been discussed before?
Background: After a year in Ac, other year in rF2, now I mainly drive AMS2 for a few months. Always felt something "wrong" in AMS2 visual coherence - the excessing bouncing (not shake, the bounce) and car rotation. I repeat, just visual feeling, not really physics related. The car visual rotation is in the wrong pivot point.
This week a well known sim has all content available to test and I drove exclusively that title.
Returning back to AMS2, there it is - that stange feeling I don't have with any other sim. I wonder if this is in Reiza concerns.