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WHERE IS LIFT OFF OVERSTEER????????????

Discussion in 'Automobilista 2 - General Discussion' started by florian ray, Mar 6, 2021.

  1. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    That sounds like plain ol' steer to me.
     
  2. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    I really don't want to go into debating your subjective feel.

    I will say this though, AMS2 does not have the off-throttle rotation you'll find in other sims.

    But we're still kind of at the 'establishing definitions' stage of LOOS though, which in my mind are pretty settled. The term is now out there like asian carp in the mississippi river and being misused to criticize ASM2 as having inferiors physics.
     
  3. Kevin del Campo

    Kevin del Campo Active Member

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    Fair enough.
    Edit: I dont feel my experience in ACC making my car break out the rear lifting off the throttle through Sunset is that “subjective” though...

    But keep in mind that a large portion of people that simrace dont have the slightest clue about these things, let alone when it gets down to having to prove your point with graphs.

    So having the discussion about what is factually LOO or not is beside the point in this case of people criticizing AMS2.
    I understand its a discussion worth having, but not in the grander scheme of things in this context.

    Im not gonna argue technical terms but maybe people are really adressing the lack of “off throttle rotation”, in which case I think it should still be adressed.
     
    Last edited: May 5, 2021
  4. Andrew Hollom

    Andrew Hollom Active Member

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    Do you mean by natural deceleration that due to lifting? Any deceleration causes a weight transfer, and since grip is proportional to normal force, then the front tyres will gain grip and the rears will lose grip, and the slip angles will be affected by this change of grip. There will be a rotational acceleration due to these changes, and this will happen with no steering input, and so is a form of oversteer, and I know you won't want to, but is this not lift-off induced oversteer? It could even be the start of snap oversteer - who knows?
     
    Last edited: May 5, 2021
  5. Synaks

    Synaks Member

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  6. oez

    oez Mayor of Long Beach

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    Yes mate. But you said:
    How does braking automatically increase rear tire slip angle? That's the whole issue here, because it might not depending on your setup.
     
  7. Synaks

    Synaks Member

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    It doesn't, however a transition from acceleration to deceleration mid corner will, I misworded that.
     
  8. Andrew Hollom

    Andrew Hollom Active Member

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    Plain old steering - I like that! Plain old steering is just grip generated from slip angles, the grip being a function of the tyres' normal forces which can be resolved into the lateral and longitudinal components. When you look at it like this by going back to first principles, then it covers all situations, static or dynamic, whatever you may choose to call them.
     
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  9. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    I understand what you are getting at. But again, the term LOOS, in common racing parlance is specifically defined to traction loss of the rears due to a sudden transfer in weight that can and may result in a spin. This depends highly on the type of car and setup of the car. The term comes from novice drivers who are inexperienced with high performance vehicles, overcooking a corner, realizing they will be going off track, so they increase steering inputs and come off the gas. This is where it the term originates and this is the ONLY context.

    If there are any principles of car weight mechanics that mimic this. braking, turning harder, full throttle while braking even...it can create oversteer, but they are not specifically LOOS.

    The issue I believe you all are not addressing, and I don't know why. is the rotation you are getting with other sims is NOT due traction loss. You are not feeding the throttle to maintain any wheel slip angles or gently coming off throttle to prevent LOOS. You are simply coming off throttle and the car turns in. The rear is planted and the front is simply gripping more. Its not LOOS and arguably not OS at all. You can talk wheel slip angles and definitions all you want. I understand them completely. LOOS requires rear traction loss at or beyond the wheel slip breakpoint. period. Ams2 has this period.
     
    Last edited: May 5, 2021
  10. oez

    oez Mayor of Long Beach

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    But how? Wouldn't the rear have to step out first? What if the slip angle before transitioning is mild and the rear is still perfectly able to grip with the load it's given? I feel like your logic is missing important steps that then go through setup variables as well.
     
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  11. InfernalVortex

    InfernalVortex Active Member

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    Some cars seem to. I know I posted elsewhere but the Sauber C9 seems to have a decent amount of off throttle rotation from what I recall. This is just based on feely subjectivism, though, but I remember that one acting much closer to what I thought it should.

    I do agree that AMS2 doesnt have the off throttle rotation other sims do. What I have also noticed is that sim racing, without the G-forces, divorces us from perceiving a lot of things correctly, so while I *think* the understeer present off throttle is bad, it could very well be much closer to accurate than we realize.

    Does your telemetry tell you the weight load on each corner of the car at different times? I know I've always felt like you never really feel any actual weight transfer happening, and I was wondering if we could put that to bed and say it's in my head or not.
     
  12. oez

    oez Mayor of Long Beach

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    This is where I'm split, because I believe that a magic LSD (no pun intended) can provide you "extra rear steering" if you will when coming off the throttle, but then also limiting so it doesn't go too far like open diff junior formulas often do. Then we can start discussing if at some point your rear tires have a large slip angle, but your front tires not so much. That would be oversteer. But often you just have a bit of extra steering so the car still feels stable. Off the top of my head I would guess that the rear slip angle is still less than front. As in not oversteer.

    But does such a magic LSD actually exist or is it just some kind ISI motor and Kunos simplification?

    962 too. It reminds me of Raceroom's Group C although again not as contrasty. That could be a lot of things including Raceroom's possibly overly enthusiastic diff behavior exaggerating the effect.
     
  13. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    It does. Is there. It even splits what components are handling the loads. spring/arb/dampers. The feeling you get driving a G40 is present in the Gt3, its just more subdued.
     
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  14. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    are you suggesting we should go on a counterattack?? because the differential data I posted from ACC looks surprisingly like an open differential throughout the entire corner, regardless of throttle inputs. Is this what a homologated diff with just a preload setting is?? Just an open diff with magic rear stability??
     
  15. Synaks

    Synaks Member

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    No, but a well designed diff will open and close gradually when you need it to.
     
  16. oez

    oez Mayor of Long Beach

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    I am a bit. But really I don't want to make any statements. Just wondering if it's indeed quite the homologation special. This is important, because as the driveline is still being fine tuned in many cars, we shouldn't expect an unreasonable end result. Not least, because I don't think Reiza will or can easily sprinkle magic on the diff.

    Do you have real world data and/or expertise on one? This is genuinely something I want to find out. I understand how clutch LSD works in that the preload, coast ramp and negative torque from the engine resist differentiation. But it's torque sensitive, not speed sensitive. What we think we're seeing in ACC is a unicorn diff that has very little lock until you reach high rear tire speed differences which is not how I imagine a clutch LSD works in practice. But this might be explained by some other factors too.
     
    Last edited: May 5, 2021
  17. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    Fair enough.

    Like this?
    [​IMG]

    Here's the V8 at Zolder from before for reference.
    [​IMG]
     
  18. Synaks

    Synaks Member

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    Do we know the radius of the turn? We can surely figure out if 6.7 percent makes sense based on that. It does seem high.
     
  19. steelreserv

    steelreserv Well-Known Member Reiza Backer

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    If you know the turn radius of turn 8 at zolder, and that makes a "diff"erence to you, i'm impressed.

    The wheel slip breakpoint for ACC and AMS2 are similiar, ~10%. So its within that, which is nice.
     
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  20. Synaks

    Synaks Member

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    I could look up the turn radius, but I'm more interested in the radius of the line you were taking if that is possible.
     

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