I have a long time concern on rear grip on rF2. I am not a hard core racer like most of you guys, so I do not dared to challenge this question until last night I took a close look at the rear tire deformation. By looking at the rear right tire, while making left turn, the deformation seems make a sense and matches with the suspension drop/rebound. However, I expect to see a little more "deflation" on the tire since the tire gain so much vertical load (increasing the patch contact area on the tire). But I don't see it. If I make a left turn at lateral ~1.2g, I shall gain 20 - 40% vertical load on that tire (depends on config of the car and suspension). I would expect a large amount increase on the tire patch contact area (I shall be able visually to see a "deflation" of that tire from that view). As we all know in general that the tire coefficient of friction dramatically increase as slip angle increases until reaches to "max slip angle". This is partially due to the fact that increasing the contact patch area to the surface of the road.
Have you seen the TGM display? Press "right alt" and "+/=". Gives you a much better representation of the contact patch you drive on. Also bear in mind that the older cars don't have any new CPM model stuff. They don't really "use" the tyre correctly, as it were. Try with the Brabham or the Cobra, might be different, who knows XD
Tire stiffness is different on each axis, so hard to tell from looking at them how much load is in it. TGM display is the tool for the job, or maybe motec telemetry.
Skippy doesn't have CPM so is a more simplistic model (right now) than more recent content. This might not make a visual difference, but you should be able to figure out via telemetry or TGM the physics going on in a CPM car.
OK,I will try those "CPMed" cars, mentioned by hexagramme. Are there other CPMed cars? Actually, I have no idea what is CPM stand for. In terms of Telemetry data, I see no such data related to patch contact area. For TGM tool, is there an instruction how to use and where to find, etc. other than Press "right alt" and "+/=" to display as Minibull said? I did find one video on Youtube for TGM tool illustration (very impressive). He did quasi static tests, and showed how to vary the load (Surface Height) and deformation (Surface Camber) on the tire. Very nice.
I'm not a content creator for ISI, but basically the tool creates lookup tables I think, where it puts the tire into a certain situation and creates a result of what the tire does. When you're then driving the sim and put the tire into that situation, it does what the tool said it would by looking at that created table. This allows you to effectively run more advanced physics than you can process in realtime. It's a pretty common technique for advanced physics on home systems. CPM = contact patch model (where we improved the actual contact patch detail levels), if you go here and click order by date last updated above the Indycar, anything newer than Apr 6 has CPM, including the Kodi rF1 conversion. http://rfactor.net/web/rf2/cars/
But yes, the rear grip seems suspiciously low on several ISI cars and this may be related to why? Joe, try comparing the Honda NSX with the Nissan 370. One feels like it has normal rear weight and grip (the NSX) and the other does not. The Palatov D4 has bite in the rear; the Cobra is in the middle somewhere (better than before it had CPM); the Skippy is on the light side; the historic F2 is balanced. Those are my impressions and it would be interesting to see if they align with your observations or tests.
^ I wonder about weight distributions ai, and their effect (excluding any other stuff like diffs, tyre differences of course, etc). The 370 is 55:45, the NSX is 42:58. The Skippy is all kinds of screwed up as it should be XD I do find the 370 very tail-ey at low speeds, but it responds well to good neutral throttle through a corner and keeping the rear loaded. What I've felt in rF2 compared to many sims is the weight transfer and how it affects the car. It was a real shocker to drive the old Race07 touring cars and compare them to the Civic...felt like maybe 10 KG were being pushed back and forwards, even when hard on the brakes into a corner. I'd like to know what power it is putting down, must be a bit more than the NSX lol. Could be it needs its aero to really feel settled, as it's only in 1st or 2nd that it's tricky for me. This stuff is so hard to know, amongst all these cars, they are all so different in design and technologies. A tiny rocketship with massive power to weight and funky suspension design A muscle car with huge power, the rest of the components "lacking" to deal with it. A well reputed and great handling road car with skinny road tyres and not a massive amount of grunt A lower class touring car with real basic aero, seems more like a stripped out road car A purpose built training car, made to be tricky to drive An old open wheeler, very light and flat with great "handling" Stands to reason they shouldn't all handle the same or provide similar grip levels, that wouldn't make sense. A whole spectrum of different vehicles, if they all did handle relatively the same, I would be questioning it for sure. But then we have no idea how they should handle exactly. I think the 370 should be a little grippier at low speed, unless someone has some knowledge about the car. I don't know the tyre size, or the power, etc etc. The one complaint for a while with the old CPM is that the cars didn't really respond right to camber and the outer edge of the tyre. You could see it with the temps. The new CPM seems to have done a lot to change that, and you can see it while driving with the TGM display. We wait and see until we get a CPM tweaked 370, see what changes.
Um, curious if you guys are considering fuel tanks when discussing the rear ends of these cars... NGTR just got an update to include CPM, by the way.
Hello everybody, For cars without CPM, I do not think it is a lack of rear end grip, but rather a lack of slip angle on the rear. Maybe I'm wrong, but CPM theoretically doesn't improve laptimes. It will make the car easier to drive and therefore may improve laptimes. Or am I wrong? As some may know, I have my own F1 2013 mod. I would love to give it the CPM, but I don't know if that is easy to mod. Is there a tool for it and/or a manual? I only have "notepad skills", so it may also be out of reach for me .
Well you'd have to use ttool at least, but the dev corner has a(n old) guide for that, basically. What is less clear is whether the tyres will have an improved contact patch just by rebuilding and making them work with the new parameters, if that's what it needs (belt spring and damper, ring damper, spring and damper per unit area), or increasing the number of sections to 200 (and therefore, presumably, an increase in the number of nodes to keep balance) is also necessary in order to qualify as 'new CPM'. If you need to redo the nodes I'd say you'd want a spreadsheet as well as notepad, at a minimum.
I am. Almost empty versus full fuel should be able to be felt and will have more or less effect depending on how heavy the original car is in the first place and tank placement, etc. The light rear end I am referring to is far more significant than any difference light versus full fuel tank would make. For example, the Skippy is a rear-engined, rear-weight biased, "tippy"-feeling vehicle compared to most in real life. That's why it's a great car to learn racing in. It still has all the rear sudden weight-shift sphincter-clenching capability that got the original 911 to be named the "doctor killer." If you are not used to rear-engined cars, it's quite a shock. BUT, let's be honest, if the Skippy or the original 911 were so delicate and tippy that they felt wobbly or unstable a lot of the time, no one would race or drive them. They only bite when you push them to and then just past the limit without realizing that they will react very poorly and very quickly to a weight shift caused by a panic move (often avoidable if you have the courage to not let off the gas and steer your way through the problem you got yourself into). Before the Skippy gets to that point of no return, it feels MORE capable than you can believe, because it's so low, light and well balanced for a race track (the rear bias allowing you to power through corners the way you cannot in a front-engined car). Just like an old 911, it sucks you into going faster and faster because if you keep your foot in it, it will just keep holding on past what you think is reasonable. And then, blam, you push it too far. I don't get that sensation when I am driving the rF2 Skippy. Right from the pit lane, it feels skittish and as if there is not a big, relatively heavy, low-tech engine hanging right over the rear axle. It feels tippy even at lower speeds and quite frankly, too scary to push if it was in real life instead of in the safety of the digital world. So does the Skippy suck? No. It still feels better than any prior similar car or the same car in iRacing. But there is just a subtle problem with either the FFB messaging or the car's planted-ness via the sim physics. I'm not expert enough to know the difference. I only know what a real Skippy feels like versus the on-screen one. Overall, rF2 has the most authentic feeling vehicles of any pro-sumer sim, which is why I am here. If iRacing's cars felt as good (and they are also quite variable quality from one model to another), I'd just stay over there. But I wish the cars felt a bit more like the mass they actually contain was transferred to my senses for the digital experience. The CPM does not really affect this. I love the CPM changes and they are without a doubt a nice step forward and feel more authentic to me. But a better-responding tire still doesn't cure the weight and weight-shift issue I am describing. And to put this all into some context, I don't think I am the only one who senses this. The fundamental appeal of AC is that it has a great feeling of weight and weight transfer. So good in fact that even though the rest of the accuracy and authenticity of it is inferior, people can immediately hop in a car and it "feels" authentic. It's also easier, so put those two together and you get popular. I don't want easier or less authentic. I just want the vehicles to feel like they have the mass that you feel in the seat of your pants when you are really driving one. A good example is the ASR historic F1 cars. Pick any one (not the 1992 mod) that is in a later stage of development. Despite no CPM, it feels authentic to me, including the aero effect at higher speeds. The Palatov feels like the oversized go kart that it is, which is to say fairly heavy steering and it takes some "muscle" to toss it around. The ISI karts respond so well, but still feel like there is a digital filter between me and the car and track...perhaps preventing me from experiencing the full "violence" those little things can kick-out when you do something stupid. I can see and hear more of the kart's reactions to being pushed at the limit than I can feel. Yet at the same time, the FFB fidelity is generally fantastic, with lots of detail and already better than any other I can find/afford. Increasing the FFB multiplier does not address this problem--it only multiplies what is already there. I am talking about something that is missing. Is this impossible to achieve, or just a deliberate "design choice" by the devs? Wish I knew.
well, I tried those cars with CPM enabled. The rear of those cars are very firm, except for the AC car. I could not tell if indeed CPM did a trick or not. I tried to do some sort of objective study by comparing two versions of same car (one with CPM and other without). I picked the Indcar DW12. Lets just look at the Left Rear (LR) tire. I drove couple laps to warm up the tires and then start to record the data (one lap data for each car at Silverstone). all aids were off. Rest settings are default. Here are the data of Lateral force upon the LR tire as cornering. You see the huge negative lateral force as while making right turn due to load transferring on this tire. I am not a good driver, trying to drive same way for both cars. Well, not easy to do so. View attachment 17927 The tire vertical deflection (deformation), shown below. View attachment 17928 DW12 is so firm for grip, it is actually "pretty hard" to get into a slide state. Of course, we can see a few moments I got slip, but most of time almost perfectly in grip (near 1 or 100%): View attachment 17929 It is hard to tell if the CPM car actually did better or not for grip. It looks like the blue line is slight higher (slightly better?). If look at the Lateral force, I drove the CPM car slower (blue line) at first half lap. It seems no diff between them. this car's grip is too good to do study for this purpose. I hardly notice any diff while driving. Maybe we shall try other cars. Note: after couple laps, this car's steering wheel started shacking like crazy. both cars did the same..... any idea why?
I wouldn't expect the CPM to give higher (or lower) overall grip. That's not the intention. That deflection data is horribly quantized, too, not that it probably makes much difference to analysis in this case.
