Вощем вроде народ просил тут опубликовать на всякий случай, собсно выкладываю черновки. Орфо правки поста приветствуются :)
I have to warn you, it will be angry post and all stuff here is only my guessing, because we will never know the truth, I suppose. Let’s begin with one of my favorites.
Q: What are the main obstacles when modeling tires?
A: The main obstacle is that nobody understands what’s going on and nobody seems to be able to figure out a consistent and reliable way to test them, so they remain pretty much a black art © Stefano Casillo
So, many years has passed, and it seems to me nothing changed in this direction. We still deal with some sort of magic. Let me introduce a short video about AC tyre model (first 50 seconds):
Car is just sliding down the hill, suspension is working, etc. Why this happening? I have no idea, I’m not a developer. Maybe Aris should tell us another story about real tyre physics? But I guess that’s because we have no wheels and we have no rolling and we have no mechanical grip in this game, we have something like snowboards and it is always sliding on surface, no matter what. If you accept this point of view, some processes with “tyres” becoming more obvious.
Here’s my story. I was pretty happy with v5 tyres in AC. Maybe it was not so good (temperatures, pressure, etc), but they gave me great feeling of overall car balance, oversteer vs understeer. I was playing a lot those days. AC gave me same feeling when I was driving my real RX-8 on race tracks. But then v7 and v10 came and for me personally it was all ruined. In my opinion all this new tyres became a crap. And here are 2 reasons for it in simple words:
1) front tyres has low “lateral grip”, in my opinion. For example, when you going straight, release all pedals and turn the steering wheel on good angle, front tyres lose grip and slide forward. It’s the same for all AC tyres and cars, including LMP1, GT3/2, etc. And you can do nothing about it. I was driving some our local championships on these cars, was pushing front wing to max, adjusting shocks to get front grip, etc – nothing helped me at all. So only way you get oversteer is when you lose grip on your rear. It’s 2 different situations and many people can’t see the difference and it is sad. No need to tell that I feel much more front grip in real life situations. Of course, sometimes some real stock cars have large understeer. Even my RX-8’s stock suspension setup had a huge understeer I can’t fight, but it can be pretty easily fixed and overridden by aftermarket coilovers, ARBs and camber-toe settings. One day we tuned suspension in a way, that my car had so much front grip, that I was overturning pretty easy on slow corners, I’ll never forget this real life’s feeling. And there is no way to simulate it in AC on v7 or v10 tyres even with extreme setup settings on “vanilla” cars.
2) rear tyres sliding to much under power on corner exits. Well, I guess roots are the same. You take semislicks, pushing the throttle on 3rd gear and you get oversteer that you will never get in real life even on less “grippy” tyres.
I drove less and less every day. Ones I realized one thing. I launch AC, I drive a car on semislicks or on streets and I know this is fake and it can’t be real! Very sad feeling for me. Driving was not fun at all for me anymore with this game. So I forbid it for a while. But one day later I suddenly remembered that v5 tyres were existed and I wanted to try it back. I’ve downloaded AC 1.3.4. somehow and launch it. And it was great for me, seriously! Those 2 problems have gone away and I just drove around on various tracks and have fun with road cars. In my opinion balance was great and it was close to reality. But I have to admin, v5 tyres was less “alive” comparing to v10 analog, I don’t know how to say better. I’ve even made a vid, take a look
If you don’t know NRing is my favorite Russian circuit and it really exists (http://www.nring.ru/). By the way you should see some real onboards with my RX-8 and slightly tuned BRZ (if you don’t know BRZ and GT86 are almost the same cars)
Btw we have a lot of grip as you see, but this is not even a semislick, its Hankook R-S3 for BRZ and Yokohama AD08r for me, which are “Extreme Performance Summer” tyres category for public roads ( https://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=EP )
Well, some time I was pretty happy with AC 1.3.4. Later I found that I can pull official tracks and modded ones to it. But you know, present AC version is slightly better and one day I tried one thing. I made a mod of ks_toyota_gt86, changed original tyres.ini and put old file version with v5 tyres. Holy crap, that worked! I was happy again and it is inspired me to dig. I’ve started to change values and look what is does. Well, you know, it is very complicated when you have only names of variables and short description of main principles, especially when main dev is a lazy mafaka, that can’t do a proper and full description of his tyre engine.
We got 2 main topics about it here: http://www.assettocorsa.net/forum/index.php?threads/tyre-model-v5-specs.29891/ and http://www.assettocorsa.net/forum/index.php?threads/tyre-model-v10-specs.36686/page-3 . I would say it is not so much useful info. Anyway I got some intel on this and I want to share it is, maybe it will be useful for somebody. First of all let’s compare v5 and v10 original tyres.ini for the same GT86 (v5 on a left, v10 on a right)
Well, I should say I never pay too much attention to temps, pressures and camber settings. In my opinion they all wrong in AC any way. 3-spot Inner-Medium-Outer temperature tyre tuning isn’t working here at all, seems to me. But you know, I don’t care, it’s not affect overall balance that much. You can see Kunos are pretty happy with their strange “ideal” values like PRESSURE_IDEAL, let’s ignore it for a sec. The key to “my problems” was SPEED_SENSITIVITY and this Load Sensitivity block (FZ0,LS_EXPY,LS_EXPX,DX_REF,DY_REF). After many blind swaps Stefano’s black magic box gave me luck! So I got a hybrid v10 tyre with v5 values I described above… and you know, it was great, really! Same feelings as original v5 but I don’t know how to say it, more alive maybe. And now I like it very much, no jokes!
So, let’s talk about super-realistic licensed official data from manufacturers. First of all any fanboy can’t blame me and say that I’m another stpd mafaka noob-modder, taking data from nowhere. It’s all original and it is all by Kunos! Deal with it, lol. Take a look at SPEED_SENSITIVITY, ROLLING_RESISTANCE_1, FLEX_GAIN, and pressure block – these values almost doubled in v10! Is it a fine tuning of tyres? It can’t be at all. I can understand when you add 5-10% to the value, but 100% - why? Maybe in 2015 (or what year it was) physics were different? Newton’s laws are the same now, right, guys? Or maybe we should rebrand it? Maybe super-realistic data was corrupted? Well, I don’t know and Kunos never tell us, I guess. I will be very happy if you prove me wrong and provide some links with explanations, really appreciate it. But instead I guess Aris will tell us another fable about hardcore tyre models and Stefano will directly kick me outta here to the library, where I should read a BOOK… but what book exactly? Maybe Alice in Wonderland? Is there an answer why car is sliding downhill at Black Cat County when it stopped?
OK, we had enough fun, let’s go back to the values. SPEED_SENSITIVITY is pretty clear for me and I understand what it is doing. But Load Sensitivity block is a black hole for me. I’ve represented this data on a graph, take a look
I’ve took v5 and v10 values and these formulas by Kunos: MULT = (DY_REF*FZ0) / FZ0^LS_EXPY, D = Fz^LS_EXPY * MULT / Fz. I guess we have current wheel load in N on X axis, but I have no idea what is this D value. Is it Damper or what?.. Somebody please help and explain me what is all about! It’s look like FZ0 and DY_REF define some kind of reference point and LS_EXPY is responsible to exponential character. But again, what is D? Of course I’ve read about contact patch but I didn’t get how to combine this all together in one piece.
Next fun thing is I have to swap both values, SPEED_SENSITIVITY and Load Sensitivity block, it doesn't work individually and car balance feels like same crap. But together they works well for me. Finally I don’t touch other data, it is all v10 original, only 2 things were changed. Later I drove about 20 laps at Magione on vanilla v10 and my hybrid each, here are results
You can’t tell me my time is slow, ‘cause it is +0.4 to RSR WR (26C/37C temp, optimal grip, no wind). I was pushing hard and the difference between tyres is more than obvious. Almost 1.4 sec on lap – that’s not a joke. It is faster just because car is now turning instead of sliding forward on corner entries.
Now, guys, I want you to try my mod and tell me what you think. But you know, I don’t want to speak with fanboys, slow guys and guys with zero real track experience because it has no sense at all. If you want to help me or provide with extra useful information – please introduce yourself first and show me your real/virtual hotlaps. I really don’t want to lose my time on trolling or “lessons from hardcore simracers”. Thank you very much for your understanding and have a nice day!
P.S. there is a little issue with my mod, I don’t know why but sometimes engine sound is missing. I use a third party Content Manager and it is not a problem for me, but you can face it, I guess. Have no idea how to solve it without Content Manager.