“ are rfactor2 physics broken” video

Discussion in 'General Discussion' started by GTClub_wajdi, Dec 29, 2020.

  1. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    My front height is already at lowest point.
    Also my bad on typing "rear CG" this is not what i meant, just to be clear.

    Just a little counter, as you are suggesting that lack of rear wing downforce means diffuser is higher...it is all good make sense but problem is that i don't have even feel the need to lower the rear if i detach the rear ARB because the car handle fine.
    And as you said the ARB should allow for better diffuser efficiency but it doesn't happen.

    So detached arb in theory should have bad diffuser effect hence if anything i should be lowering the rear with detached ARB
    but it is opposite in RF2, not only i gain no aero benefit of stiffer ARB on underbody but it is more in need to lower rear ride height although it should control the CG AND underbody aero better.
    Again not just one corner.
     
    Last edited: Jan 7, 2021
  2. Bruno Gil

    Bruno Gil Registered

    Joined:
    Oct 12, 2020
    Messages:
    115
    Likes Received:
    73
    Fair enough. Are you willing to lower rear ride height and retest? I still think the intended * result would show.

    I also see you are avoiding to adress some of the points I've raised.. Even taking the CG correction into account, I don't understand the raising front splitter part, and you are still assuming you need that big of an amount of rake for aero* to work
     
    Last edited: Jan 7, 2021
  3. Stefan_L_01

    Stefan_L_01 Registered

    Joined:
    Nov 18, 2012
    Messages:
    586
    Likes Received:
    377
    We can see issues even with limited telemetry
    check this: these are 2 charts of the Corvette gt3 C7 in a circular accelearation. Springs soft.
    The essential formula you have to build up in motec is sus_force/sus_pos which is c, the spring stiffness constant. This is the top chart in shot 1. As the acceleration in 6th gear is slow, this is a quasi "steady state". ARB removed so its about normal springs. Damper minimum to minimize forces due to oscillation. Packer ZERO (0 "null" ..)

    What you can see is that at a pretty early point, the more or less constant stiffness is broken and stiffness increases rapidly. This is for the rear happening with a ride height of allready 42mm approx!!!! And the ride height actually takes a plateau there, so something "new" is happening, propbably the bumpstopper taking over. The increase in continous as the new real stiffness is based on an allready bigger amount of suspension travel, so the graph shows not a "step" to a new stiffness logically.
    42mm rideheight is not much if you can set up the car for ridheights 53mm statically, even less if you think that tire deflection IS included in the rideheight. The front is noch much better, hitting bumpstop at 37mm. Both WITH PACKER 0!!!

    The C7 is running on the bumpstopper around the corners, yet is is pretty performing.
    Or is it performing because someone pushed it in front by giving it more downforce or other performance, compensating a wrong bumpstop / suspension model? If someone can avoid the bumpstop issue it might become an overperforming car?
    So much wrong, so much visible even with limited telemetry
     

    Attached Files:

    Last edited: Jan 7, 2021
    Pawel44 likes this.
  4. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    https://forum.studio-397.com/index....sics-broken”-video.68348/page-15#post-1054324


    Sry i edited it a bit too late
     
  5. Bruno Gil

    Bruno Gil Registered

    Joined:
    Oct 12, 2020
    Messages:
    115
    Likes Received:
    73
    If you take in consideration you have no idea what the "base" roll resistance is, you can't just say that in theory it shouldn't work. All you can do is test different approaches, to see if each individual part is working as intended. So, once again, all is null until you actually lower rake and test again.
    Also, just because you don't feel the need to, doesn't mean the car isn't faster if you do it.
     
  6. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    So even though stiffer ARB should be helping downforce it needs lower rake
    Meanwhile detached ARB should be generating RELATIVELY less downforce and it is following the line with no problem... you see the issue.
    Detached rear ARB is faster with low wing compared to P4 rear ARB with low wing.
    Front was at P4 in both settings.
     
  7. Bruno Gil

    Bruno Gil Registered

    Joined:
    Oct 12, 2020
    Messages:
    115
    Likes Received:
    73
    Let's get back to the beginning. You said AFTER lowering rear wing increasing arb (in general? You seemed to imply in general at first, and now you say rear arb only) would get you oversteer; I hypothesised that the extra rear height due to lower wing was stalling the diffuser. And you refuse to test this hypothesis, instead backing it with what YOU think should happen, discarding other very important variables.
    So I'm gonna sum up my point of view. If the diffuser is stalling as I said, messing with arb is not gonna do it anything since its not working in the first place (0 x a is always 0).first you need to get the diffuser to engage, and only then can You test how the arbs influence it.
    If we discard the diffuser, increasing rear arb (once again, you need to keep your stuff consistent: rear only or both?) had the intended effect: balance shift forward.
    Once again, you have an easy way of knowing: test it!
     
  8. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    9,602
    Likes Received:
    4,613
    No, I meant ride height is measured at the undertray points, not at the wheels. So knowing where those are (HDV file) can help with understanding, and would be useful when working out what factors influence ride height. One of the reasons I tested with my own mod is I know where the points are. DLC doesn't let us see the HDV (completely separate to telemetry).

    The rest of your post I'll need to catch up on later, at work now.
     
  9. Andregee

    Andregee Registered

    Joined:
    Jun 23, 2012
    Messages:
    832
    Likes Received:
    322
    Use Motec I2Pro an compare the rubber temperatur channel , with the shown temperature in other sims and you will notice the same behaviour. The surface temperature in rFactor2 hud says nothing and it its simply not usefull. I also don't understand why you only get the surface temperature displayed in rFactor2.
     
  10. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    I will test it more carefully today.
    I clarify what happened
    I tested rear ARB only on RSR (I also tested detaching both ARB but i didn't pair it with low wing, i will also give this a shot)
    Current situation is on rsr i ran on zandvroot gp. Front P4 ARB is same for both situations and wing is at P1.(lowest one)
    First without Rear ARB and low wing
    Second with P4 rear ARB and low wing.
    Results are->>
    I got more grip overall with detach arb on low wing, surprisingly more in faster corners.
    On Rear ARB run with low wing car felt more agile in low speed cornering and faster corners i got noticeably more oversteer, on all corners phase entry mid exit.

    Today i will try same but i will lower rear by 3mm-4mm and see what happens.
     
  11. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    This is what I use actually, I posted screen captures in a later thread.

    I never said I was only getting surface temp, not sure what you are refering to.
     
  12. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    9,602
    Likes Received:
    4,613
    @Yzangard the "you" in that post didn't mean you. It meant, "I don't understand why only the surface temperature is displayed in rF2"

    But, while I do get that for setup purposes, the surface temperature is the most relevant for the question "How much grip will I have right now?". So you can't ignore that either...
     
  13. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    @Bruno Gil I tested it again today at same values.
    P1 wing and P4 Front ARB as base.
    Then tested with
    1.P4 ARB rear only
    2.detached ARB rear only
    3. Lowering ride height by 5mm on P4 ARB rear only

    My old results are still correct i.e i get more oversteer with P4 Rear ARB with low wing throughout the lap on old zandvroot GP in RSR.
    Detaching rear ARB gets me better grip with low wing.

    I tried with lowering rear ride height by 5mm and still detached ARB is providing more grip despite running on higher rake.

    One small correction i was running 12mm (not 11mm) rake 5.0cm at front and 6.2cm at rear. So even when i dropped rake by 5mm (rear at 5.7cm now and front at 5.0 cm) the P4 rear ARB STILL gets more oversteer.
    At 12mm rake detached rear ARB is still out gripping rear P4 ARB at 7mm rake.

    I expected this results before testing.
     
  14. Stefan_L_01

    Stefan_L_01 Registered

    Joined:
    Nov 18, 2012
    Messages:
    586
    Likes Received:
    377
    I recommend to go on a skidpad, use damplugin for motec data, and get data in a controlled way (steady state driving) to understand whats going on rather than driving in a useless way here and there on a track and shout out non-proofable info.
    I use the euskatel test teack (ett) which can be downloaded somewhere.
    We had to remove Arb for rsr in the 24h races 2 years ago in lm to survive, some remove rear arb in the lmp2, no secret, yet questionable of course.
    I can show some effects later
     
    Bruno Gil likes this.
  15. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    i don't use motec, if you could try out and show some results that would be great. but so far detaching ARB not just rear is way to go.
    in long run you only need to detach rear arb and use fron arb for understeer.
     
  16. Yzangard

    Yzangard Registered

    Joined:
    Dec 6, 2018
    Messages:
    351
    Likes Received:
    173
    @Slip_Angel Just to let you know, I tested the "oversteering" trick you mentionned with S397 F1 car (can't remind the name but not relevant) and I can confirm it is suspect, to say the least.

    So I tried in ACC and iRacing and in fact, you can almost do the same thing, only problem in ACC is the flat spots (in rFactor 2 as well, I had serious vibrations the more I did it, my smooth setting is only 2) and in iRacing, issue is the over sliding tires made the trick almost impossible to use efficiently.

    The point is it doesn't seem to be that incredible but there are consequences, maybe not as hard that it should be but there still are consequences.
     
  17. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    IMO the operating window of tire , car chassis,aero in RF2 is too big. they can be made to work with extreme driving , setup etc and still no big issues. These are race cars they don't tolerate such bad stuff weather it be driving or setup.
    This is why even the best road car journalist (like chris harris) that can play with hypercar with ease is left in back field while driving these "gentlemen" race cars.(GT cars)
    people sometime defend such forgiving behavior by saying that they are customer race car etc , i honestly think that is BS. even the gentlemen purchasing this race car HAS go through good training. EVEN then they are nowhere near PRO driver level.

    Whenever PRO racing driver say they need confidence inspring car/setup , i don't understand because if RF2 is good measure of realism then i don't see how much more easy these racing driver wants car to be. but when i drive in ACC i can see why they need more confidence inspring car and setup.
    P.S ->> i don't find cars in ACC more challenging because of FFB , just to be clear. numb FFB was never an issue for me. infact i use light FFB in every sim just to train myself not to rely on it.
     
  18. AMillward

    AMillward Registered

    Joined:
    Apr 4, 2017
    Messages:
    1,810
    Likes Received:
    1,754
    That's what race licenses are for ;)
     
    Bruno Gil and Remco Majoor like this.
  19. Slip_Angel

    Slip_Angel Registered

    Joined:
    Jun 15, 2019
    Messages:
    588
    Likes Received:
    297
    you missing the point of my point comment. besides that is not what i meant by saying training.
     
  20. Bruno Gil

    Bruno Gil Registered

    Joined:
    Oct 12, 2020
    Messages:
    115
    Likes Received:
    73
    Your testing methodology is still far from ideal, and results like "understeer" and "oversteer" are subjective rather than objective. I do think you might be onto something (even tho a lot of stuff can explain that behaviour - mainly: You're changing steady state balance for oversteer, and you sure as hell feel that, independently if aero is working better or not) so I'll try and test that properly: with motec in a car with no locked channels.
    Changing both arbs would be more correct as you would be change roll stiffness as a whole and not on one single axle, which will Always have balance consequences
     

Share This Page