Cars Physics reworked for the two Maserati 250F 2019-09-13

[mclarenf1papa]

1. Steering turns is not particularly important
2. You “fixed” it by adding 7% error to its center of mass location. The better way would be to find a genuine issue and fix that instead.

 

[alekabul]

1. Steering turns is not particularly important
2. You “fixed” it by adding 7% error to its center of mass location. The better way would be to find a genuine issue and fix that instead.

In that case what is the genuine issue with the 250F`s? Why so wobbly and understeery?
Steering turns 2.5 vs 2.0 is important more so when half of the time is occupied by correcting the wobble that adds itself to the real polar inertia and you find that crossing your arms is not an option as it`s not enough.
"7 % error" ?? We were talking about moving CG 4 % to the rear and if it`s a big thing here.
To save time, here`s what i suggest - you do the math`s and upload the correct physics and I`ll be very glad to drive it. Deal?

 

[mclarenf1papa]

In that case what is the genuine issue with the 250F`s? Why so wobbly and understeery?
Steering turns 2.5 vs 2.0 is important more so when half of the time is occupied by correcting the wobble that adds itself to the real polar inertia and you find that crossing your arms is not an option as it`s not enough.
"7 % error" ?? We were talking about moving CG 4 % to the rear and if it`s a big thing here.
To save time, here`s what i suggest - you do the math`s and upload the correct physics and I`ll be very glad to drive it. Deal?

I don't know what the issue is, or if there even is one at all. I know that your "CoG Fix" is objectively wrong though (7% error is the 4% change in sprung mass). Same with how entering spring rates directly into the files is objectively wrong. It's not great to talk with such authority about things you don't understand.

 

[alekabul]

Once again, I`m not even trying to argue but to understand. And maybe lure you to do a proper edit of 250F Just try driving it hard and you`ll spot the problems too.

 

[alekabul]

I don't know what the issue is, or if there even is one at all. I know that your "CoG Fix" is objectively wrong though (7% error is the 4% change in sprung mass). Same with how entering spring rates directly into the files is objectively wrong. It's not great to talk with such authority about things you don't understand.

For my self improvement would the "Assetto Corsa Car Modding Worksheet" be of any help? You find flaws in the math`s in that?

 

[Kyuubeey]

I don't understand how driving the car hard will outline any mistakes. I haven't exactly driven a 250F hard on track, nor did I take video and telemetry if I would have driven it so my opinion is almost irrelevant. Even I don't base my roadcar physics improvement mods on just "I feel it's wrong"; there has to be something else as well.

I don't know if the KS car is completely correct, probably not due to various reasons, but you'd be surprised just how difficult some early formula type cars were. This one handles really well. If you can find some good onboards and anecdote from drivers and you find something you think is off, you should probably take a look at the suspension and tires first. The longitudinal CoG is one of the things that could be considered correct.

 

[Fat-Alfie]

You also appear to have 'corrected' the power.lut Your version now has a huge boost at the top end of the rpm range, feeling more like a turbo has kicked in.
Kunos' 250F vs your 250F

Has this come from real data that Kunos didn't have access to? Or did you just make it up?

 

[Kyuubeey]

I'd like to use this moment to inform you that torque doesn't actually reach 0Nm at 0 RPM.

Power is dependent on torque and RPM, and is the only thing which matters anyway, so at 0RPM, you will however have 0kw power = nothing moves, no energy generated.

Very cute.

 

[alekabul]

You also appear to have 'corrected' the power.lut Your version now has a huge boost at the top end of the rpm range, feeling more like a turbo has kicked in.
Kunos' 250F vs your 250F
View attachment 324565View attachment 324566

Has this come from real data that Kunos didn't have access to? Or did you just make it up?

The quotation for the top-end power of V12 is in the car`s description. Look it up for yourself in the web sources I provided. I`m even convinced that it`s minimal according to the description of a car that "eats up its tyres and has problem finishing a race" because of the 1500 rpm usable rev range at the very top near 10000. It most certainly is not a fantasy. Powers are at the crank because it`s not said in the sources that they were measured at the wheels.

Also that "dyno" on the left is only what Kunos put in the "ui_car.json" of the cars. The "power.lut" are very different and you should look at them in CM or the online tool from x4fab. The power of the Kunos cars absolutely needed correction.

 

[alekabul]

I'd like to use this moment to inform you that torque doesn't actually reach 0Nm at 0 RPM.

Power is dependent on torque and RPM, and is the only thing which matters anyway, so at 0RPM, you will however have 0kw power = nothing moves, no energy generated.

Very cute.

I can`t help it if I`m cute. For the AC game if graph and power is 0 at 0 rpm does 0 difference because even the dumbest AI knows to rev up the engine prior to launch. So I`m not gonna waste time for clarifying why real dynos are not applicable concerning the lower end of the graph.

 

[Kyuubeey]

I can`t help it if I`m cute. For the AC game if graph and power is 0 at 0 rpm does 0 difference because even the dumbest AI knows to rev up the engine prior to launch. So I`m not gonna waste time for clarifying why real dynos are not applicable concerning the lower end of the graph.

The issue is what you do to the rest of the curve because you assume you need to have 0 torque at 0 RPM.

 

[alekabul]

The issue is what you do to the rest of the curve because you assume you need to have 0 torque at 0 RPM.

As you I too prefer for the curves to use the online tool from x4fab. So practically they end up not so different even with 0 power at 0 rpm or otherwise which is easily provable by changing only the first line from "0|xxx" to "0|0". The graph doesn`t change at the top end.

 

[Kyuubeey]

As you I too prefer for the curves to use the online tool from x4fab. So practically they end up not so different even with 0 power at 0 rpm or otherwise which is easily provable by changing only the first line from "0|xxx" to "0|0". The graph doesn`t change at the top end.

You say that and yet you created a curve which is by shape more akin to a large turbo single turbo build. Can't you just admit you don't have the slightest clue what you're doing?

 

[alekabul]

You say that and yet you created a curve which is by shape more akin to a large turbo single turbo build. Can't you just admit you don't have the slightest clue what you're doing?

Simply put - no.

 

[Rufus Baggsby]

Simply put - no.

Seems I have ignited a hot debate here, which wasn't my intention.

The passion and enthusiasm of the AC community is a wondrous thing and it is often reflected in the emotive tone of such discussions as these. I think most of us would admit that we are still learning and what's even more relevant, that we have never actually driven the vast majority of the cars we work on in AC. This tends to influence our expectations of how a car should feel when driven and the temptation is to try and match the physics to our expectations rather than to the real life nuts and bolts. Even if you commit to authenticity there always seems to be a few assumptions and educated guesses to be made.

For example I really doubt that ARBs were fitted to the 250F, yet you have one defined for the front suspension, supposedly to eliminate the wobble you complain about. Your redesigned suspension has its front roll centre well outside of the chassis, so maybe this is also having an effect on stability?

The 250F used a De Dion rear axle at the rear with a transverse leaf spring, but AC cannot emulate this. The closest you could get would probably be DWBs with an ARB rather than the solid rear axle with no ARB in your model. This would also give you control over the rear roll centre and hopefully make for more authentic handling..

I don't mean to criticise, just to inform and before you tell me to do better myself, I don't have time as I'm already working on the magnificent, but uncontrollable Mercedes W125. (Unofficially of course. I wouldn't release anything without the original modder's knowledge or consent.)

One really worthwhile tip is to change the sounds.ini from
[ENGINE]
POSITION=rear
to 'front'
Many Kunos cars seem to have this as a default regardless of their engine position and most mods have this same error cut and pasted.

It makes for a better sound when you're in the cockpit... at least I think it does, but no doubt someone will tell me it isn't used anymore since the FMOD switch.

 

[alekabul]

Seems I have ignited a hot debate here, which wasn't my intention.

The passion and enthusiasm of the AC community is a wondrous thing and it is often reflected in the emotive tone of such discussions as these. I think most of us would admit that we are still learning and what's even more relevant, that we have never actually driven the vast majority of the cars we work on in AC. This tends to influence our expectations of how a car should feel when driven and the temptation is to try and match the physics to our expectations rather than to the real life nuts and bolts. Even if you commit to authenticity there always seems to be a few assumptions and educated guesses to be made.

For example I really doubt that ARBs were fitted to the 250F, yet you have one defined for the front suspension, supposedly to eliminate the wobble you complain about. Your redesigned suspension has its front roll centre well outside of the chassis, so maybe this is also having an effect on stability?

The 250F used a De Dion rear axle at the rear with a transverse leaf spring, but AC cannot emulate this. The closest you could get would probably be DWBs with an ARB rather than the solid rear axle with no ARB in your model. This would also give you control over the rear roll centre and hopefully make for more authentic handling..

I don't mean to criticise, just to inform and before you tell me to do better myself, I don't have time as I'm already working on the magnificent, but uncontrollable Mercedes W125. (Unofficially of course. I wouldn't release anything without the original modder's knowledge or consent.)

One really worthwhile tip is to change the sounds.ini from
[ENGINE]
POSITION=rear
to 'front'
Many Kunos cars seem to have this as a default regardless of their engine position and most mods have this same error cut and pasted.

It makes for a better sound when you're in the cockpit... at least I think it does, but no doubt someone will tell me it isn't used anymore since the FMOD switch.

Well, going by numbers:
1. Take a look at the Kunos "setup.ini". See the "min=15000" for the ARB? I forced myself to go a bit outside of the "setup.ini" only for the ARB so the car gets rid of the uncharacteristic understeer.
2. Front roll centre of both 250F`s should be exactly what Kunos did as I did not change the length and orientation of any arms.
3. Effect on stability was achieved mostly from lowering the giant fuel tank to it`s real height and correcting the tyres and rims.
4. Solid rear axle with no ARB is exactly what Kunos did, but I see your point. And don`t agree with it - the DWB would have change drastically the dynamics of the rear wheels laterally and DeDion is known to have the wheels parallel at all times. Kunos chose their substitute correctly. DWB would give the model a far better handling than what could have been really.
5. As my focus was on the physics I didn`t look elsewhere for problems. Will correct that "sounds.ini" but without uploading an update. On my home sound system the difference from "POSITION=" is nonexistent.

I`m glad to see some criticism and can take it, don`t worry. I`ll do my best to learn. Best wishes to you and hope to see that W125 in action soon.

 

[Kyuubeey]

Hey, I'd just like to take this moment to remind you that the rim diameter doesn't have any effect on physics. It's just to determine the ground collisions. You'll need to modify everything else for it to actually do anything to driving.

 

[alekabul]

Hey, I'd just like to take this moment to remind you that the rim diameter doesn't have any effect on physics. It's just to determine the ground collisions. You'll need to modify everything else for it to actually do anything to driving.

I strongly disagree, again from my own FFB experience with AC. Rim sizes matter for the physics, more specifically for the cornering.

 

[mclarenf1papa]

I strongly disagree, again from my own FFB experience with AC. Rim sizes matter for the physics, more specifically for the cornering.

They don’t do anything besides serving as a collider for if the tires pop.

 

[Kyuubeey]

You can look into the code yourself to confirm it if you want. Or make the rims absolutely massive or tiny and check, but I bet you'll still placebo something.