We’re kicking off Friday the 13th here at PRC.net with a lengthy piece concerning everybody’s favorite topic – Assetto Corsa’s lack of simulation value. Today’s Reader Submission comes from JZ Studios Online, who has kindly penned us an extraordinarily detailed piece discussing the game’s highly controversial tire model. The entry essentially serves to back up Sev’s recent findings, where longtime Assetto Corsa players are noting the overall driving experience seems to have been neutered in preparation for the next generation console release. This is one you should probably grab some snacks for – there’s some reading comprehension involved.
Good afternoon, PRC. I don’t know if you guys are still able to patrol the Assetto Corsa forums or not – I keep hearing you’re banned – but I’ve had a recent spat on the forums inside the Forza 6: Apex thread, and wanted to draw attention to it. This might take some time to elaborate upon.
To produce a brief summary, some guys were toting how much better Assetto Corsa is than Forza, when they can currently only play Forza 6: Apex on a gamepad. My counter-argument was that Assetto Corsa is on relatively even terms with Turn 10’s newest release, citing the inherent understeer and the lack of full throttle wheelspin. After taking a lot of fire, the heavens themselves opened up and Lord Kunos appeared to offer his guidance:
“Educate yourself, buy four to five books about car dynamics, and spend the good part of the next three years studying and understanding them. Perhaps, then, we might have a chance of a serious discussion. Until that point, please go back on the thread topic, and stop derailing the discussion into a sim war nobody is interested in. I wouldn’t like to have to close the thread because of you, and I won’t; I’ll rather let you go for a couple of weeks.
And while you’re at it, practice some driving as well.”
Now, for a bit of context. There’s an astrophysicist/game physics guru named Brian Beckman, who has worked on many racing simulators including Forza. I’d like to share with you the following video. As a word of warning, this piece is over 60 minutes long.
It’s honestly a brilliant video where he describes the complexities that go into a proper tire simulation, and a full vehicle simulation. I know it’s a bit long, but I think it’s well worth a watch.
And to which Lord Kunos replied:
“Pretty comprehensive for 1990, too bad it’s 2016.”
I responded with a snarky “true, but too bad he’s using Windows XP, which came out in 2003. It’s not like physics suddenly change from one year to the next. What calculations do you use for slip angles on the longitudinal and latitudinal axis then, if not official lab data? I mean, if you guys really found something new and groundbreaking that actually makes that outdated and irrelevant I’d honestly love to know.” The original Forza Motorsport was also released in 2005.
I bring this piece back to the original comment by Lord Kunos, and I indeed followed up on what he’d suggested. I did some research. And he’s the biggest lying cunt I’ve ever seen. Still, I was not about to be out-assholed by some smelly bald Italian, so I gave a quick whip back with this:
“You know what, you’re right, I’m sorry. I forgot that in the space between 1990 and 2016 the physics forces applied to tires had changed. After doing some suggested research, I found that you are correct in everything you say, and certain forces that acted upon tires in the days of yonder no longer do today. I found some interesting articles provided by the largest tire manufacturer in the world about how they managed to locally eliminate forces applied to the tire, thus producing certain friction-less elements. I think the world’s largest tire manufacturer should have pretty reliable information.
While we were in brief discussion, I did not start a sim war. I brought up that I find the cars to understeer and your fans retaliated. I don’t want to have a war, or to make people angry, but if the mere discussion of one sim versus another makes people upset, then I’m afraid I don’t know what to do. I’d like to pursue the truth and find out for myself, but having fanatics on both sides clouds the picture and gets no answers. Much less when the head honcho himself comes to jump in and say his piece, but instead uses that opportunity to not try and connect with a customer who PAID for his product, but instead decides to turn to insult. I personally am not offended easily, but when someone asks for an explanation, when did it become acceptable to call them an idiot, and incapable of understanding?
Doing my research after one article, I stumbled upon this page:
For a real quick summary: He’s talking about Beckman’s video and the current issues with using the Pacejka curve model. Namely, the Pacejka curve shows the amount of force/grip a tire has at all points. The problem is, when not moving, or moving in a straight line, the model comes closer to a divide by zero situation. This required a lot of older sims to use a secondary physics engine below a certain speed where you could tell things were different. Using the Pacejka curve at a near zero velocity causes the tires to oscillate quite violently, more so than acceleration or braking.
The problem is, the tires never actually return to 0 velocity, and so the tires are still constantly moving. In the link above is a video of an early iRacing tire model where this anomaly causes a car to slide down a hill, since the tires are constantly moving ever so slightly in that direction, regardless of brakes being applied. And again, this has nothing to do with whether or not transient tire effects are modelled or anything to do with the complexities of measuring transient phenomena in a tire on a tire rig. The same thing will happen regardless of the tire model used as long as slip ratio is used as a direct input into the tire model in this manner.
So, I’m sure AC has figured out that problem, but it does raise some questions. For me the biggest is why does Sir Lord Kunos the Magnificent claim this information is outdated and irrelevant as I’m currently watching the slip angles and slip ratios freak the fuck out and go well beyond standard operating range while simply sitting still. He straight up insulted me and lied to my face, all so he and his little stupid forum fanatics can go suck each other off as they spank the hankey and touch nips. I am now actively motivated to tell people to stay the fuck away from game and doing my own research to find the flaws with it to see what His Glory and the Fourth Reich have to say about it.
On a side note, I’m trying out the Mercedes SLS, a car known for being bat shit fucking crazy and spinning in circles on corners, and I’m finding that impossible to accomplish without the handbrake. Not only is there under steer, but the tires WILL NOT slip coming out of corners under full throttle. I’m also no expert, but I’m pretty sure that when I full throttle it through a turn my RPM’s should raise a little more than not at all. How dare I try and point any of this out on the forums though, in that case I’m a fucking lunatic who can’t drive.
You may not care about this at all, but at least the video and the article are worth a read. I just thought it might be nice to share some information with someone who isn’t bat shit crazy and hasn’t drank the kool-aid of imperfectly perfect physics. In the same argument, people agree that the physics are perfect, but I’m still an idiot and I can’t drive, because the physics aren’t flawed, I am.
It’s no secret I’ve been active on SimRacingSystem over the past few days, and it’s allowed me to evaluate the current tire model within Assetto Corsa in a competitive environment. Unfortunately, what Sev had found originally has only been strengthened by my own participation in these pickup races. The cars are indeed significantly easier to drive compared to the Early Access version of Assetto Corsa, which is obviously a step in the wrong direction considering the overall goal of a racing simulator. There’s little to no throttle management on corner exit, the vehicles don’t exhibit a fine dance at the limit of grip laterally, and despite the Soft compound tires really getting a workout according to the tire application, only the lap times are any indication that the rubber underneath me is degrading. It honestly feels a bit like Project CARS. You just sort of point and shoot. The little shit that you have to do in isiMotor sims, like nursing the car to the apex or carefully rolling on the throttle… Yeah, you don’t have to do that anymore.
I mean, I could have just gotten the setup right, and I’ll attach it to this post so others can try, but it’s like Kunos have taken all of the talent out of wheeling a car around at the front of the pack.
As for Stefano, his stubbornness, and the general inability for Kunos to take criticism, I must ask where you’ve been for the better part of a year? This isn’t really anything new. At this point, we almost need a focus group for all the major sim racing developers, where they can role play with each other and create methods to help them handle genuine criticism – not everybody is going to treat them in the way their private Skype clique does.