Physics discussion thread

Not really ?

 

Dear Reiza team, I have been a fan of AMS2 since release but only joined this forum today to ask this question: could it be that the weight of the car in the input sheets of the cars is in kilograms but that the Madness engine calculates with Newtons? I often have the feeling that the car does not weigh enough and does not push enough onto the road. I was wondering if maybe a factor 10 (kg to Newton conversion) is missing? For example, formula v12 feels light to me and so do the GT3s compared to other sims. Maybe it’s a stupid question or it has been addressed already, but I thought I give it a try anyway. Please keep up the good work!

 

Newton is unit of force, not a unit of mass. These are 2 different things

 

that’s exactly my point: if the Madness engine calculates with Newtons, then the input variables need to be in Newton as well. Frankly, I don’t know anything about the Madness engine and was only asking the question out of curiosity

 

The values shown in the UI are from my understanding completely decoupled from the values used in the physics. When new vehicles are in early development the values can often show up as 0, which is a value that cannot be divided by, so we would discover it very quickly if the values in the UI were used in the physics directly

This is likely due to two factors: Force feedback and camera settings.
Some of this is within your control to change, other aspects are up to Reiza to improve upon.

 

Typically a physics engine has far more complex calculations - it's not as simple as "using the wrong unit" as a fixture will have particular attributes such as density, weight, and friction levels that are used by the engine to determine how things work. So, your 'force' calculations will then be taking into account weight, density, friction, speed, air resistance, etc.

But, I agree with Roar - how heavy the car feels to you is a product of FFB and camera settings.

 

Lets continue this conversation here, its better.
First I'll say, AMS2 has a far more oversteery tendency than understeery one, thats true, and my biggest problem has always been the initial rotation on throttle that you get on some cars, but the idea that you can't overload the front tyres in the sim is simply untrue. Kinda of a dumb video here to show my point:

Obviously I'm exagerating my inputs here to prove a point, but even in 2nd and 3rd gear corners this mclaren is going straight on throttle, this also was recorded with 0 TC to make it even harder on the rear end and the car understeers in the situations I'd expect, through turns 3 and 4 I floor it while turning to see what happens and the rear moves a bit until the front gives up, turn 9 is the same story as turn 3 and then turn 11 on exit is the same story as turn 4, if I keep flooring it the car will go into the gravel. You can even see at T1 in the second lap while the car is rotating on the brakes into the corner I go on throttle and it inmediately starts going straight.
In sims it's all a matter of values, I personally believe the tyres sidewalls are a bit too soft in the GT cars and they tend to move on the tyre too much, which is what leads to this tyres having a bigger slip angle than expected, but I don't think you always end up managing oversteer in any corner, I'll depend on the car, track, conditions and setup.

 

I also completely disagree that it is "impossible" to understeer in AMS2. I've driven a whole bunch of different cars in the sim and every single one of them I have done my best to optimise front-end grip. Perfect example I have at the moment: McLaren MP4-12C Retro 3 F1 car. Understeers like crazy if you don't get the line right on corner entry. It also drifts beautifully - so if you lose the tail end, out of every car I've driven I can actually recover a slide 99% of the time. I'm not sure if that's due to recent changes but it's been a lot of fun

It's also very easy to "fix" the snap oversteer by simply reducing engine braking strength in the cars affected by it.

 

Yes, corner entry is fine like i previously said.
This video with Formula Ultimate Gen2 is my point. No matter how much i steer, the car keeps rotating to the direction i point my steering wheel even in complete front end slide.

Apologies for quality, i had to record VR footage since the replay is lost otherwise in free practice.

 

I mean, the car has decelerated from 250kmh to 180 in the span you entered the corner, in a qualyfing setup this cars run this corner at an entry speed of 270kmh all the way to 205kmh, ofc if you enter the corner at this speed the car will just keep rotating, it has enough downforce to do so, if however you do the same at a higher speed the outcome is very different:

And if you want the car to rotate less in this situations the easiest thing is just to reduce front downforce, it's going to be slower however..

 

Obviously i'm showing the physics behavior here, not driving a competitive lap.
Watch how it rotates; in a huuuge controllable front end slide. Not even Max Verstappen could replicate that with a real formula car.

 

So your point is that the rear should snap in this situations?

 

What would the alternative be to a 'huuuge controllable front end slide'? What is turning if not that?

 

Sorry, I must be blind because I don't see any dramatic front slide or you applying a tons of rotation in your video.

There is plenty of rotation on that car on the default setup. I have done a lot of testing on tyre wear (which is too low IMO) on that car and when the wear finally starts to kick in, you get more "to your expectations" style of behavior, where you actually have undertsteer to think about. If you would change the setup and weaker the front, to have that intially, you probably would be struggling more when the wear kicks in.

To me, that car isn't a example of wide slip angles in AMS2, on the contrary, it actually snaps and also understeers when i expect it to (the default setup is just a bit biased towards rotation, you have plenty to spare with in the beginning)

My favorite way to test is to do 30min stint on Silverstone on softs, trying to push a bit all the time (but not too much to make sure you don't fail with your test because of mistake). You can turn up the tire wear of course too.

 

Nah like i’ve stated i quite like how the rear behaves in this sim.

Look, i’m not an expert but in my experience there is many possibilities what can happen when the front is in aggressive slip angle;

1. Front tyre traction snaps back and upsets the car. This is salvageable with a skilled driver but not always

2. There’s too much grip loss and you can’t control the car with a steering wheel. Instead the front just slides uncontrollably.

In AMS2 neither really happens. The slip angle is very gradual and is rewarded with more rotation and grip. Thus you always end to initiate the front slide and turn the wheel super aggressively.
OFC there is some limits how much speed you can carry and how much you can steer, but it’s very easy distinguish it and drive the corners in happy controlled front slide.

That’s why i picked that car and not a GT car to showcase it!

 

Well IMO regarding your points I'd say it like this.

1. If you get sudden front tyre traction snap what you'll get is sudden understeer, this could only happen if you keep aplying throttle while turning in a front limited car, you'll then get a point where the tyre stops working and just slides, this is pretty well shown in my mclaren video around BCN. In the video you posted, with an F1 car, just lifting up the gas makes the cars decelerate aggresively, the drag in an F1 car is enough to produce 1g of deceleration at high speeds, corpse corner at silverstone is a good example, about 30kmh deceleration just by lifting the gas and turning, without touching the brake pedal.

2. if you got massive understeer and then front tyre snap, it'd be because there's been a sudden regain of grip due to something external, for example, if you have too much front downforce going into a high speed corner, turning the wheel too much inducing understeer and then bringing it back, you'd get a sudden snap of the rear. This can also happen by modyfing the setups, it won't do it with the regular default since those setups are supposed to be drivable out of the box.

For me, the behaviour shown in both of our videos is not incorrect, the Fhybrid is, IMO, a bit too fast compared to real life, but the general behaviour of the car is, again IMO, fine.

EDIT: Also, its important to say, what is "aggresive slip angle"? F1 tyres have a ton of slip, thats their only way to keep up with the massive speeds that this cars generate around corners. With this I'm not saying the car, or any other car, is perfect, but the idea that there's an overall physics problem with every single car in the sim is what I don't agree. It's all about setup, driving and track state

 

Let's look some real footage for a bit:

Especially at the Würth curve and at the Rindt.

What a beautiful lap, clearly Max loads the front tyres a lot.
But the tyres fights back; they want to snap back to traction.

So you can load the front tyres IRL a lot, but it isn't gradual smooth sailing.
It's more demanding, dangerous and the window to hold the slip is much smaller.

In the end AMS2 is an excellent sim and by it's forgiving nature people can drive easily 1:04 at Austria and feel like a proper F1 driver.
This sim is five years old now, so ofc there won't be major revisions to physics and i'm glad to hear the core community clearly enjoys it in it's current state.
I too enjoy it a lot- i think AMS2 does many things better than other sims even in physics department.

 

Thats why I said the Fultimate is a bit too fast, the current lap record is 2 seconds faster than this, but in the case of Verstappen's lap I can see a car thats mainly setup to be slightly more front limited than rear, makes sense since F1 cars have to run both qualy and race with the same setup, so the car has to be able to cope with a Full tank of fuel and harder tyres, so qualy performance isnt entirely reliable compared to the sim where we can just drive cars at the most peaky. I assume that in a perfect world engineers would lower the car even more since there wouldn't be any penalty for wearing the plank down.

But going back to this overloading front tyres, this is my lap and the current WR at Barcelona modern with the V10 g2. I can say from experience that this car was drivable thanks to the traction control but it was hard on corner entry, very easy to loose the balance and spin it, I almost did at turn 4. But the car also had understeery tendencies at high and low speed corners (Look at T3 and T5, my steering input in T3 literally doesn't change and the car just drives to the edge of the track). I can't see any overdriving on the front tyres to achieve this lap:

And if you want a demanding car to drive, I'd recomend the FReiza in Time trial at this same lap.

 

Nice lap mate!

When i watch the car's trajectory, in my eyes you grip slide the front tyres in every corner
Takes some skill to have a WR with a F1 car that's for sure!

 

Then lets just agree we have a very different view on car physics