“ are rfactor2 physics broken” video

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

  1. Jack Dyson

    Jack Dyson Registered

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  2. Raintyre

    Raintyre Registered

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    It is so simple that you don't need to risk your life trying it with a car. Just do it with a bicycle and tell us your experience with the low pressures. Describe what you feel and take scientific measurements of temperatures, top speeds....
    How do I dare to compare a bicycle with a Formula 1? Very different "scenario" !!!!
     
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  3. Lazza

    Lazza Registered

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    I think extreme low pressures, and realistically we're talking outside of setup ranges here, should be handled with some specific effect/parameter separate to the physical model. It's not worth the effort.

    For low pressures within a reasonable range, I can only assume people want excessive heat and uneven wear? Neither of which is going to hurt on one lap.

    Setup pressure range should reflect reasonable values. Going lowest for laptime isn't a bug, there just should be some detriment on longer runs. We can't see degradation (heat history) or wear balance directly, but experience says this isn't really a factor in rF2.

    A lot of other things mentioned (rolling resistance etc) can be tested directly in ttool.
     
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  4. Raintyre

    Raintyre Registered

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  5. Lazza

    Lazza Registered

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  6. Bruno Gil

    Bruno Gil Registered

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    Actually the bycicle thing is still explained by what I said. I will use arbitrary values (and most likely waaaay too high) so u understand.
    Imagine u make 5hp with your legs. And now let's say that running the tires with lower pressure than "ideal" produces a force (drag) that requires 3hp to counter. 3hp is 60% of what you produce (5hp),so you will sure as hell notice it.

    Now a road car in regular driving. Let's say your road car has 100hp. And let's say that running lower pressures than ideal will, in this case, due to extra weight, more wheels, etc, requires 10hp to counter the forces.
    In regular driving you will probably use half (if that much, probably a lot less) of your engine power, so let's say 50hp, so in this hypothetical case, in regular driving, you will spend 20% of your power counteracting that force, which will make the car go noticeably slower, and/or noticeable lower gas mileage.

    Now if you go flat out on that engine, the extra drag is just 10% of your total power, so now the effect is effectively halved.
    Now you pick a Racecar with about the same weight as this road car, and about 350hp. The required power to null the drag is still 10hp,but that is now just a mere 2.86% of your available power.

    Should need no further explanation.

    And, once again, as the wall of text I just posted suggests, it is NOT that simple
     
    Last edited: Feb 12, 2021
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  7. Raintyre

    Raintyre Registered

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    You are very optimistic using those figures. And also remember that racing vehicles usually mount aerodynamic devices to produce big levels of downforce. As downforce increases with speed, tyres are pushed stronger to the road. At maximum speed the load on tyres can be 2X, 3X the vehicle weight or more, and roll resistance force rises linearly with weight. (Linearly if we are optimistic).
    They are spending big budgets on high efficiency aerodynamics to obtain some extra tens of a second per lap. It would be strange to lose five seconds per lap for not inflating the tyres
     
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  8. Raintyre

    Raintyre Registered

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    You can try yourself. Put a ridiculously 2kpa to your tyres in dev mode and let me know how it drives and what is the correlation with reality.
    It is very strange that you are defending those obvious flaws, when you are providing a telemetry plugin.... Your plugin works great, but channels data is created by RF2, so many of data that your plugin is reporting is fake, videogame fantasies, science fiction, not something that can be observed as realistic or useful for a professional of motorsports. And you seem to be satisfied about it, I can't understand it.
     
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  9. Bruno Gil

    Bruno Gil Registered

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    And yet again, the only reason f1teams don't use lower pressures is because pirelli doesn't allow them, for safety reasons. I did mention those were arbitrary values, and I'm actually pretty sure the drag figures I gave are actually way too high. But since you apparently are an expert on the matter at hand, I'm once again withdrawing from this thread, as I'd rather drive than argue with know it alls on forums

    BTW, dragsters use pressures as low as 4psi. are dragster physics broken? Or is it because they can afford to due to the massive amounts of power they have? And probably the lack of lateral forces to pull the tire from the rim
     
    Last edited: Feb 12, 2021
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  10. Yzangard

    Yzangard Registered

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    Not the right place indeed :)

    I have a Simucube 2 Pro as well and it works really fine, I could share my own config file so you could adapt to fit your needs, come to me in PM if interested.
     
  11. Lazza

    Lazza Registered

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    You completely misread my post. @Havner If you like that, you obviously did too.

    It's not possible to discuss things in this way.
     
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  12. Havner

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    It's not possible to discuss if you ever get misunderstood?
     
  13. Lazza

    Lazza Registered

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    If people can't read a 2 line post, yeah. Maybe I should have done a wall of text instead o_O
     
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  14. Yzangard

    Yzangard Registered

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    Yet I fail to understand what makes you think that telemetry data are fake, can you elaborate a bit about this ? This is convenient but you didn't explained anything to make your point.

    As far as i can tell, after comparing with real car telemetry and even other sims, I can't spot anything that seems "fake".

    Now of course, the roll resistance is indeed not present as you "reported" but this is another story, we can see in telemetry that roll resistance doesn't exist, at least not enough. That being said, the minimum pressure is what is allowed in official BlancPain : 140 Kpa. This pressure is low but not "incredibly" low, it is just dangerous to use this pressure because tire would not hold but I don't think it would create a lot more roll resistance when compared to 150 or 160 Kpa cold...
     
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  15. Comante

    Comante Registered

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    Is he another incarnation of slip angel?

    Beside this today I stubled in this video, and I found some details remarkable to the discussion, or at least to improve our comprensione of the tire stuff.


    In short, the interesting remark is that apparently, tires can keep performing while sustaining continuous cornering at notable slip angles for several kilometers in a row.... at almost 400 Km/h
     
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  16. David O'Reilly

    David O'Reilly Registered

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    Have you ever found that such aggressive critical rhetoric has helped find a solution to an issue.

    I am also curious to be pointed at a consumer simulation that has the tyre modelled better than RFactor2.
    Please advise?
     
  17. mantasisg

    mantasisg Registered

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    If having mod with custom lowest pressures like 2Kpa or even 0kpa (haven't tried negative numbers yet lol) is still fast. The sim itself should not allow lower than atmospheric pressure in the first place IMO. It is logical to suspect that in this simulation there could possibly be a lack of factor that could otherwise bring a disadvantage in some circumstances if that factor was presented.

    In case of rolling resistance, it would be top speeds hit primarily, but there would be some impact at all speeds that could begin from thousands of a second then end up with multiple seconds loss in tracks such as classic Le mans with open Mulsanne straight, especially with big downforce as Raintyre has pointed out.

    Also rolling resistance will have some contribution in cornering, when load transfers from one side of a car to other, logically on one side rolling resistance would decrease, and in other side it would increase, it should be more apparent with no camber or even negative cambered road in turns (much less with big bankings that will have more equal increase on all four), ideally it should probably work a bit as stabilizing mechanism by adding resistance for overturning, although it would probably be negligible in comparison to load sensitivity in most cases.
     
  18. mantasisg

    mantasisg Registered

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    Do we really know what exact pressures does F1 use ? For example in track like Monza, where top speeds are probably most important across all F1 events ? Also F1 cars has huge amount of drag, it might make tire rolling resistance insignificant even even in track like Monza, however, it might not as well. A single Kph in the straight can be important. So basically I wouldn't be sure if it is "the only reason" why they don't go lower, I would be interested to know where are you sourcing this knowledge, I doubt it is the only reason.

    I am not sure about 4psi (26kpa) in dragster tires. I am fairly sure that it is actually 126kpa in those tires, because gauges are zeroed at atmospheric pressure. And yeah certainly with the power they pull and the duration which they drive rolling resistance is probably not something they think about, possibly they don't even think about aerodynamic drag, apart when they deploy parachutes.
     
  19. Bumble

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    Used to get away with that low
     
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  20. Comante

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    Dragster tires increase in diameter due centrifugal forces, so much that the vehicle itself is raised from the ground, rolling resistance for the low pressure is non existent then.
     

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