How Tire Slip turns into Tire GRIP! - Combined Slip and Grip Explained! (somewhat, possibly) 

You don't do that already since day 1 of sim racing? WTF?

the sound quality is pretty bad though :D

@@rideroundandstuff how is it bad? It's no studio setup or what Ermin Hamidovic uses but he can be understood perfectly.

@@rideroundandstuff I kinda sound like this.. I'm using an 'omni' ModMic that sounds better than their directional ones and a small mic amp thingy . The noise floor isn't great but its really more than fine and better than 9/10 gaming headsets in my opinion!

I listened to it on my phone's speaker yesterday and the amount of crackling was absurd. Now I listened to it again with my headphones and it's perfectly alright. Sorry. Funny though, because the sound quality of my phone's speaker is alright otherwise.

@@rideroundandstuff Probably my GENIUS being too much for the poor speaker to cope with. I get it all the time, my wife often doesn't hear what I'm saying either. ;-)

This is not always going to be true, some tires may not drop off at all, some a bit more.. And if your tire is melting because of the sliding, the drop might be considerable.. But its not the reason of 'breakaway' as seems to be often hinted by articles and books on 'how to drive'

@@NielsHeusinkveld I see, the drop off isn't because of the tyre loses grip, its that combining longitudinal and latitudinal slip causes the tyre to no longer have any MORE grip to provide. I can definitely feel this is sims like project cars where if your rear wheels spin you die, as compared to irl when 125cc TAG karting as long as you have quick wheel work and accurate and intelligent throttle movements, any reasonable slide is savable and a certain amount of sliding is fast.

Careful what you wish for.... ;-)

The thumbnail is quite amusing. You're getting good at this RU-vid lark. I can see PewDiePie quaking in his boots as his subs are lured away by the temptation of your spreadsheets.

Maybe he's using a mirror

You see that it follows a friction circle, but what you don't see is the loss of lateral stiffness (initial steepness of the lateral curve) when you add braking slip ratio as I demonstrate here.

@@NielsHeusinkveld I've always thought it would be interesting to visualise the available grip with a dynamic traction ellipse of max available long. and lat. grip that changes size and shape and displays the current operating point at each time step. Always been too busy with the engines day job (cool t-shirt!) to see if the reality of this matches what's in my head.

Thanks!

That might also be because the weight of the car shifts forward when releasing the throttle.

Sometimes I wonder if some of these sim devs ever drive to work? Or do they take the bus? I imagine all pcars devs ride the bus.

Abrupt full throttle lifting would move more weight on the front than 'just enough throttle lifting' so that you restore cornering grip without taking all acceleration away. So your best bet indeed is to avoid too much weight transfer to the front by figuring out how much or little to lift. Easy to underlift though and still spin out.. Tricky stuff this race car at limit business!

No idea! I was very relieved to see that AMS follows pretty much what industry standard models do. To any serious sim developer this information isn't rare or too hard to figure out. But how each sim does it is hard to tell without them telling us. :-)

Yes, I ignored that so we could focus on the combined slip at one load, rather than changing everything. Its best to not FULLY let go of the throttle, but just enough to restore lateral grip, while not transferring as much weight to the front. And common mistake, the rear rising doesn't mean its getting light. On stiff or weird suspensions, the rear can even sit LOWER when you lift off the throttle. The height of the suspension does not indicate weight transfer per se. Stiffer or softer suspensions also don't really make a difference as far as weight transfer is concerned.

Oh that would be really cool. I'd love to see it!

Many things can do this of course.. I frequently see people going on the brakes hard, and then coming off just as fast, removing load from the fronts and reducing the ability of the car to turn-in. The hardest part of braking is getting off the brakes and starting turning in.

Very late reply.. In AMS, there is a big text file that has grip multipliers for different surfaces, say 0.5 for grass, 0.9 for concrete, 1.02 for the racing line, 0.95 for curbs etc. I don't know how other sims do this but I would imagine it is similar!

That is an essential part that I kept out to simplify it. Obviously when braking, tire loads on the front increase while the rears decrease, affecting the available front and rear grip quite a lot as well.

AMS takes the lateral velocity to compute slip angle and when velocity nears 0 you get issues yes. I heard it does 'something simple but clever' near standstill but I have never looked into it. By default the 'low speed' behavior is gone at around 40km/h which I often change to a lower speed so I never really encounter it. Until AMS 'parallel parking' edition is released.. Probably you get some divide by 0 errors or big / weird numbers near 0..

I have it in the sheet but that looks at grip, not at slip. So you can't really see if a point on the circle is the result of silly slip angles or ratios. Perhaps I'll show it in a future video.

Niels Heusinkveld True, it wouldn't work on its own, just thought it would be nice to see it alongside these graphs.

I understand your disappointment. :-)

When its 'on power oversteer'. If you're mid corner zero throttle or brakes, and you're sliding, the 'feel' is still probably not really 'drop off' but more a 'sudden loss of expected grip increase'

Niels Heusinkveld Surely must also depend on which wheels are being driven? RWD, FWD or AWD, shouldn’t break away in the same way, adding downforce also complicates this further. I feel that the more information you give us, as a calculus problem it’s too difficult to calculate in real time. My guess is that’s the real crux of the problem as there has to be latency with the return signal as the circuit is feedback not feedforward, and as that’s digital there would logically be a quantization limit dictated by the cpu core clock rate, Im thinking its qubits or bust plus an inordinate amount of tire data from the manufacturer. Wondering if there might even be some tensor calculus involved as well, effing nightmare if you ask me. We’ve only just got circuit modelled compression that will run in real-time and that’s a much simpler piece of code, even valves are simpler to model than this.

From wiki tensor calculus page Tensor calculus has many real-life applications in physics and engineering, including elasticity, continuum mechanics...

Its a silly car I made for Jimmy Broadbent and myself only, its not released and is unlikely to ever be. (you're not missing that much!)

No it is quite a bit more complicated than that. You wouldn't get the initial slope changes visible here and in all combined slip data you can find.

Ah yep, my main focus is beyond the initial slope. Just trying to piece all the bits together as I figure it out. Videos are very helpful :)

From the little I know this works fine for pure and combined slip. Of course you'd have to add some parameters for load sensitivity, peak slip that moves, temperature, and perhaps a dropoff as I belief by default the brush model just saturates.. But its a bit out of my comfort zone, I'm not aware of the pro's and cons enough.

overdriving might happen here... you said you are at the limit of the car.. but there is no fixed limit of a car... for example when steering too much you reduce the amount of grip the tire can create because you are past the optimum slipangle... so you reduce the limit of the car... in that case steering less can give you more grip... or steering to fast.. the heavier a car is.. the lazyier it is.. because all the mass wants to go in the direction it is already traveling... if you suddenly turn the wheel very fast, the car has not enough time to shift the weight to the outside.... so it just scrubbs over the front... you can try that when going in a straight line.. if you turn slowly to x degree of rotation.. the car will follow.. if you turn very quick to x degree of rotation the car will scrubb some time before it turns or have a initial movement then scrubbs then turn (depending on the car and how fast you turn) ... light cars are more responsive because less mass that wants to keep the direction... so the heavier the car the more time you need to set it up for the turn.. like you are talking to it.. "there is a corner coming soon.. let us get all the mass shifted so we can travel around the corner" .. and there are many more things like how much you brake while trailbraking since you are "stealing" cornering grip by braking grip... so trailbraking is a delicate thing.. you want to have the weight shifted to the front and the time you gain by trailing your brake into the turn.. but you want to balance it so you don't robber all the grip away from turning... also you may don't want too much weight on the front to not overloading the tires... thats why fast people may brake a bit earlier but not as hard or releasing the brake a bit more or earlier to carry more speed through the turn.. because yes slow in fast out... but if you can get more speed through the turn you are even faster out because you already had a higher cornering speed as a base to accelrate from... and well more and more things.. but in short... try to go slower to get quicker... relaxe and set the car up for the turns... try not to force it to turn but let it anticipate the turn.. let it roll if needed (for example long turns).. to not steal any cornering grip by accelrating or braking... be smooth with your inputs... especially with heavier cars... on light cars like formula cars.. you can be quite aggressive with inputs while still have a smooth car.. sometimes it is even needed to be quite aggressive to keep the car smooth but fast... but the heavier the cars get like gt cars for example... the smoother the inputs needs to for them to be able to react to your inputs... otherwise the just don't do anything and want to go straight... so if you are asking how can I go faster when I am already at the limit... try to raise the limit of the car... with your inputs and driving style... the less forces it needs to struggle with the more headroom of limit the cars have... I had that in the past too... I raced mainly formula and lmp cars and such things... and then joined a gt3 league.. and I thought omg.. why I am so much slower... it wasn't the ability to not react fast enough.. quite the opposite... I was reacting faster then the car can do.. so I was driving over the limit of the car.. which sets the limit of the car even further down...(makes it slower) ... I was trying so hard to go even faster and faster and there was just a very marginal improvement in laptime if at all... till I got frustrated and thought well.. I don't even try to go fast anylonger.. I just roll around now like a grandma... and ding 2.5 seconds better laptime ?!?!? wtf ?! Then it clicked in my brain... so pace is all about trying to keep the limit of the car as high as possible... it's about telling it what to do in a calm way.. so it doesn't get upset and reject to work with you... the lighter and more engineered towards racing it gets the more you can expect it to do what you want fast... but the heavier it gets the more time you need to give it to do the work you asked it to do .. otherwise it says no and quits the job :) so if the car understeers it means the front can't handle what you asked it to do... so try to let it do less ..so it can do the job...

I'm afraid its just a driving skill issue. Plenty of world records have been set with entry level equipment.. Pretty hard to pinpoint what you're doing wrong but its probably a few things!

Niels Heusinkveld If it’s my self then it’s easier to fix, i will try with a different pc (i now have an intel and will try with amd, who knows)! Your pedals are great (i previously had the Fanatec V3’s) the sprints are miles away in term of quality of built and the smart control software is really helpful! Thanks for your support! I will keep you posted for my findings regarding my issue!

@@silviutudorescu8114 no equipment you change is going to make any difference, your problem is skill not equipment (certainly changing your CPU for another is gonna make zero difference, a CPU does maths, they all do the same maths, if they didn't programs wouldn't run, of course this is known or we wouldn't have computers). Honestly dude, it's hard to know where to start, I would strongly recommend a couple of rl track days; as you don't seem to understand how the the dynamics and weight distribution of a car effects how much overall(lat/long) grip a tyre has as the normal force exerted on that tyre changes. Feeling this in rl is way easier than in a sim, but the understanding helps sim driving generally. Car setup can play a substantial part in this; doing car setup and learning to drive at the same time is a tricky business. Try with someone else's quick setup for a particular track and then learn to drive that setup, as it's very likely setup to trail brake well, with correct toe/camber/caster and suspension for the track. Sorry for the brutality, but you'd be much better off not wasting more money on sim kit (when what you have already is superb) and spending that money on track days/rl instruction.

Tyrant Worm Thanks for the explanations on where i can look into more, i guess i have to study indeed more on car physics and how to apply that weight transfer on braking vs acceleration and cornering. It’s good to know that perhaps it’s not the gear!

Not that I have seen, but the lack of all evidence can also mean they DO drop off to some degree..

Accelerometer data.

That's how I feel most of the time too, don't worry! :-)

Niels Heusinkveld Sorry it was bugged for me, couldn’t watch it for some reason, will watch it now