How does tankslappers work ?

Discussion in 'General Discussion' started by mantasisg, Aug 26, 2019.

  1. Slip_Angel

    Slip_Angel Registered

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    What i experienced from ACC that generally front tyres have grip during low speed slides i.e when aero grip is not working hence slide is generally a mechanical grip issue
    so generally most of the time at low speeds front tyres will always have grip and you will rotate just on rear side.
    BUT
    when power is enough to slide at higher speeds where aero grip is working then ONLY at low slip angles the front have grip so you can normally slide BUT this FRONT slip angle allowance at high speeds where aero is working is much lower compared to low speed slide, hence at higher speeds the front tyres also lose grip IF the slip angles are big enough at high speeds then it causes 4 wheels drift. 4 wheel drift SUCKS it doesn't even help to rotate the car(which is the reason why you want to slide) all it does is just throw the car out of the turn like centrifugal force.
     
  2. mantasisg

    mantasisg Registered

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    Yeah mechanical grip balance forward, and aerodynamic balance rearwards is pretty basic stuff, though you should be able to change it with setup of course.

    It makes sense as naturally sliding should me more severe at higher speed, and that is for various reasons. But at smaller slip angles ? I'm not sure. Makes no sense that at high speed front slip angles somehow reduce, that would make sense without downforce maybe. Even though aerodynamic balance is rearwards, front still gets it's share of downforce, unless it is some weird system of that vehicle. Perhaps thats just aero stalling at little bit of more angle ?

    But I don't know specific stuff. Perhaps with downforce cornering stiffness increases ? This means that the slope of slip curve gets steeper. But as much as I know optimum slip angles should even increase with increasing load (so with downforce obviously)... hmm maybe not for all tires ?

    Maybe at high speeds you aren't able to use more slip angle than past peak without bad consequences, because at high speed sliding part of the contact patch will be just much less useful than it is at low speed ? If so, then at high speed there may be just less of a tire that has a chance to do the job preventing a spin out to happen ?

    On the other hand if front tire looses it's effectiveness pretty fast as rear tires does slip into oversteer at high speed, it can actually work as preventing solution for a tankslapper to happen, because obviously you are most likely not going to regain full front grip at way different timing relatively to regaining grip at rear, and this should actually help to stay in control. Is this all about setup of a car and perfect balance at all times ? Or maybe it is something that is too forgiving in nowadays simulations ?
     
  3. Slip_Angel

    Slip_Angel Registered

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    Maybe my choice or words were wrong,by saying smaller slip angles i meant that you can't slide at high steering lock at higher speeds especially in aero cars.
    I think this kind of behavious is realated to setup just as you said aero balance is generally at rear,so IMO it's pretty realistic.
     
  4. Korva7

    Korva7 Registered

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    Maybe the speed sensitivity of the tire has this kind of effect. It should degrease the amount of grip at least.
    Btw. the speed sensitivity is the thing that the latest tyre model update in rf2 had effect on, degreasing it. As reminder, the blog post basically says that contact patch got longer and cars feels less slidey and more stable in high speed corners now.
     
    Last edited: Aug 30, 2019
  5. mantasisg

    mantasisg Registered

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    Yeah, it should add up to the highspeed edgyness. Not sure about slip angles, maybe only friction ?
     
  6. slatanek

    slatanek Registered

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    Great thread!

    BTW the moment you regain grip after a slide (just before the backend goes back the other way) is called - rather counter intuitively - a PAUSE in racing lingo. Strange name considering it lasts maybe a tenth of a second at most.
     
  7. Korva7

    Korva7 Registered

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    Here Lewis almost having a tank slapper.
     
  8. mantasisg

    mantasisg Registered

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    Very recent tankslapper.


    Stigs tankslapper
     
  9. Korva7

    Korva7 Registered

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    I think i managed to get a tank slapper with the updated gte bmw.
    Edit: I wasn't using tc.
     
  10. mantasisg

    mantasisg Registered

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    Thinking about tankslappers made me rethink my understanding of springs and dampers. I used to think that softer setting will make for more grip, just make car more sluggish. But now I think that it is not that simple, also even more so with different suspension geometry designs...

    I am not entirely sure, but feels like stiff setting might be more dangerous in terms of tankslappers. I actually though the opposite, because I thought that soft settign would keep tires on left and right loaded more equaly. But on the second thought softer setting will result in more weight transfer, just slower load transfer. So soft car will slowly build weight transfer and load transfer, and it will do the same backwards when car begins to stop sliding. Slower change from sliding to static friction is reducing danger of a tankslapper, but slides are lasting longer. Now stiff car will initially slide more severely, but it also will restore weight distribution and load distribution back to optimum faster (assuming tht it will not spin out), as cars is stopping to slide, it should stop sliding faster, thus also requiring more precise and faster steering.

    Am I thinking correctly ? My recent experimenting with physcs of cars seems to be proving that it works like that.

    Now I think why would you then want car that is stiff and is fast to break loose, and then fast to grip again that it becomes more difficult ? I suppose the answer is that there is likely less sliding happening, which means faster pace and less tire wear. Also high downforce requires stiff springs, to keep car from bottoming out, right ? Maybe not even only aerodynamic downforce, but mechanical downforce too in tracks with heavy compression zones... Also it is not an issue in sims now, but IRL tires scrubs into body if wheel moves upwards a lot.

    I am not sure if in terms of oversteer there is a possible solution to make a car to be fast to re-grip, but also easy. I think that is not possible, unless sliding friction and static friction are not very far from each other for given materials that are in contact.
     
  11. Emery

    Emery Registered

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    Here's an example of a tankslapper by a softly sprung Ford Fiesta ST… jump to 0:20 if you won't want to waste a few seconds.
     
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  12. mantasisg

    mantasisg Registered

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    This must be slowest tankslapper in the history of the universe. But interesting to see that going on with FWD car, in the wet, at such speed. Was never expected.
     
  13. Emery

    Emery Registered

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  14. Emery

    Emery Registered

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    Beginning is a normal spin, 2:00 is the tankslapper
     
  15. mantasisg

    mantasisg Registered

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    at 1:28 in the video

    Well this is obviously all held and controled. Can we call it a tamed tankslapper.

    To me it is a tankslapper too, because you can see the front end motion being towards outside as powerslide ends. When you drive and this happens, it does feel a bit like if front end would get pushed a bit out of where you were intending to go. Obviously because not straightening front wheels fast/precise enough. This is just an example that at some degree a tankslapper might not make any harm, so there is a bit of tolerance and margin for error for a driver to make and still survive :D

    You can see brack battling it the whole time in this video, it appears like if it is not as challenging to catch an oversteer, as catching the car straightening back from oversteer, quite obvious

     
  16. Emery

    Emery Registered

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    Yes.
     
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  17. 2ndLastJedi

    2ndLastJedi Registered

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    I remember back when I was 17 my friend was doing a burnout in his RX3, 2nd gear it just gained traction kicking the car sideways and in his panic and lack of talent tried to counter steer while keeping his foot planted only to be back and forth until his beautiful RX3 hit the gutter bounced up taking down a telegraph pole and landing on a parked car!
    I believe tank slappers happen when people don't understand the weight shift and lack the wheel control to correct the initial slide.
     
  18. mantasisg

    mantasisg Registered

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    I don't think that it takes only this. There is so much more about how traction works and the timing of it.

    I mean even the professionals get some of that, which I have pointed out in videos above, and not always ending up in a spin, or having a very gentle "tamed" tankslapper. It just simply shows the mechanics in action. Not having them is not simply getting used to steering and skill, and mysterious weight shift stuff.

    check out this Ben Collins describing a tankslapper mechanics pretty well here 2:45-3:45


    I think he did a tankslapper on purpose at 5:34
     
    Last edited: Sep 29, 2019
  19. 2ndLastJedi

    2ndLastJedi Registered

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    My mates tank slapper was all about the light overpowered car with sticky tyres and a locked diff and of coarse the rather large amount of no skill ;)
     
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  20. mantasisg

    mantasisg Registered

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    I don't deny it, but I mean there are more to it from the physics perspective, but of course all of that is true.

    Pardon me, I just want to look at it unnecessary more deeper :D

    Less power means less danger to break the traction more quickly. However in case of oversteer to avoid a tankslapper more power might come in handy, because you may be able to manipulate rear end slide for longer, so you have few miliseconds more to point the front tires to the right direction before rear tires snaps into the static grip.

    Sticky tires must be absolutely increasing the probablity of a tankslapper, I don't think sticky tires could work in other way. But tires are very complex device, thus perhaps if sticky tires due to something (maybe wear) would also have higher sliding friction, it would help to reduce friction contrast between sliding and not-sliding. I just assume such tire would wear a lot. Anyway.. very difficult subject. Even though if difference between kinetic and static friction would be smaller, the speed of grip change is also very important parameter.

    IDK about locked diff. I don't feel like I understand differentials well, but I think locked diff should help to keep tires spinning for longer. More open diff perhaps could make car to grip up sooner, thus it would be more twitchy ? Though locked diff also makes wheels more likely to spin.

    Lack of skill is of course out of discussion :D

    I am working and experimenting with physics now, and I find that slower steering rack also makes it more likely to receive a slap from the rear. Also it has to be true in case of a heavy steering. Ironically, larger steering ratios makes steering lighter, vice/versa faster steerign rack is heavier.
     

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