Endurance Oreca 07 lift to drag ratio

Discussion in 'General Discussion' started by avenger82, Jun 19, 2018.

  1. avenger82

    avenger82 Registered

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    I have a question regarding possible issue in latest Oreca 07' lift to drag ratio (L/D) which bugs me. It's regarding a post that "mclarenf1papa" made on RaceDepartment forum:
    "The car generally feels quite floaty (tire related + the moment of inertia seems very high to me) and if I'm reading the telemetry correctly, the aerodynamics are certainly not right. Based on telemetry, the car's maxing at a 3.3:1 lift to drag ratio with the default aero setup (and reasonable ride heights at speed). The worst LMP2 of the current generation (by far), the Riley, has a 4.2:1 max L/D. The Oreca's should be around 5:1. That's somewhat concerning considering S397 say they had input from a number of teams.

    That having been said, I'm not hugely familiar with the telemetry output in RF2, so I could very well be missing something with the aero (though the drag, front DF, and rear DF outputs seem pretty self explanatory)."

    https://www.racedepartment.com/threads/rf2-endurance-pack-released-new-trailer-added.155266/page-8

    I said it's not likely and asked about how he did his measurements and this is what he replied:

    "Unless the telemetry's logging incorrect data, the car has a problem."
    [​IMG]
    "The bottom two sections are math channels I did to verify that things lined up (tire load is correctly related to downforce - the "weight front" and "weight rear" values should hover around the correct weight of the car) and calculate the L/D. The rest is straight from RF2 with the motec plugin."


    So can anyone confirm or deny this issue? @Michael Borda maybe?
     
    Last edited: Jun 20, 2018
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  2. SPASKIS

    SPASKIS Registered

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  3. liakjim

    liakjim Registered

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  4. UsedMomo

    UsedMomo Registered

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    It seems Heusinkveld was involved with the pack, so I bought it. Another issue listed in that same thread that I can confirm is a bad AIW file that causes the Oreca to continually wreck at Palm Springs Road Course B. This gentleman has offered to fix it on his own time when he gets the chance, but he shouldn't have to do S397's job for them. This needs to be made an official fix in the main branch.

    Ace King said:
    The Oreca AI are working perfectly at Palm Springs Road Course A with no wrecks but on the Road Course B the AI can achieve more speed going into T1 thus occasionally going a little wide with the tires hitting the grass causing them to spin. This can easily be fixed with some tender loving care in the AIW. When i get some free spare time i'll fix this issue!
     
  5. avenger82

    avenger82 Registered

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    I think you are being too harsh. For instance I didn't know he was AC modder. This doesn't necessarily mean anything, and of course he can criticize other mods. It's actually good that he found the issue ( if it's confirmed or partially true), so that maybe S397 will look at it and eventually fix it. So far AFAIK no one from S397 looked at it. It would be best if S397 did independent measurements to confirm/deny the issue. Maybe there's a flaw in mclarenf1papa's methodology. I was hoping, that at least someone else will try to confirm the issue is real.
    But, I guess if he's good modder than there's a good chance it is. That would be disappointing to me because that's not what I was expecting from rF2's official content. Especially if it's paid DLC and supposedly with best physics that was based on detailed, real data. On top of that in release S397 emphasized they worked closely with teams to achieve best possible result.

    Admittedly, even if the issue will be confirmed I'm not sure how big deal it is. Perhaps this inaccuracy is compensated by other parameters (like tires grip) to match actual handling, lap times, telemetry output etc. So I will still be getting this DLC pack, even if it's confirmed and hope the issue will be addressed.
     
    Last edited: Jun 20, 2018
  6. mclarenf1papa

    mclarenf1papa Registered

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    Wasn't planning on it, but made an account since a number of things could use clarification. Thanks to @avenger82 for posting it here.

    Not quite; it was actually a problem of the tires not having enough load sensitivity, leading to the development of a new load sensitivity model for AC. The aero was actually fine but it was lowered a lot ("stalling") at low ride heights to compensate for the new tire model still having too much grip at high loads. Now, it's possible to make it quite accurate, but only through custom lookup tables.

    For context, I've worked with a number of real life teams on LMP2/LMP1 cars for AC, so I'm quite familiar with the type of car in question. As stated in the RaceDepartment thread, the Riley data I referenced is from someone who helped run its wind tunnel tests. Even the last generation of LMP2s had higher L/Ds than that. I have no idea where the data on Mulsanne's Corner comes from, but it's certainly not from a competitive car (also it's the map average, which on its own doesn't tell much). Acura leaked data from Windshear in their promo video for the ARX-05 last year and its L/D was around 4.7 (and that car's just an Oreca with a flap at the front).
     
    Last edited: Jun 20, 2018
  7. avenger82

    avenger82 Registered

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    If you got info from real teams than I guess you are right.
    Still I would expect to get some feedback from S397 and hopefully their measurement results. At this point it's unlikely, but maybe there's some other explanation for this discrepancy, that's why I would wait for their acknowledgment and confirmation.
    But perhaps you discovered some fundamental flaw in rF2 physics engine:)
     
  8. avenger82

    avenger82 Registered

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    Which cars have you worked on? So far I saw 2015 Oreca FLM09 from IER Car Pack #1. I had it installed for some time, but unfortuately didn't try.

    Back to the original issue - so far no one confirmed or denied the issue. I was expecting some kind of acknowledgement from S397, but I guess if the issue was not disproved so far, it means it's more likely to be real problem.
    Anyone knows how or where can I officially raise a ticket/issue? In this forum's support section or some Discord channel? Maybe just informally ask devs @Marek Lesniak or @Marcel Offermans?
     
    Last edited: Jun 22, 2018
  9. mclarenf1papa

    mclarenf1papa Registered

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    The only publicly released LMP I've done is the FLM, which didn't have much data beyond the chassis/suspension side of things. Besides that, I've worked on two LMP2s and two LMP1s for teams/manufacturers as private projects.
     
  10. UsedMomo

    UsedMomo Registered

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    That's interesting! What software were they using, and what were their opinions on it with regards to physics?
     
  11. mclarenf1papa

    mclarenf1papa Registered

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    It was all done in Assetto Corsa. One of the drivers said he felt it was "95% accurate" with the remaining 5% being things you can't simulate (g-forces, etc.). Subjective opinions aside, the telemetry was very close as well. Anyway, let's try to stay on topic. If anyone has further questions you can send me a PM (but bear in mind that I can't disclose all that much in any case).
     
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  12. davehenrie

    davehenrie Registered

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    So because of the NDA, you cannot tell us the Air Speed of an Un-laden Swallow?


    :)))))
     
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  13. Gevatter

    Gevatter Registered

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    What do you mean? African or European swallow? :)
     
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  14. Devin

    Devin Member

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    Okay here we go:
    According to our team logs the Oreca's L/D ratio is way over 4. This information was made with our team setup so I won't tell you exact numbers but your claims are definitely either bullshit or you clearly didn't log correctly.

    Also @mclarenf1papa thanks for making your incorrect logs public and starting to get people over at racedepartment on your side before even trying to contact S397 about this matter, or anyone else with knowledge about this topic. Now random people use this as an excuse to spam the rF2 discord with even more bullshit.

    Check your numbers, fix your setup or whatever, then you'll see that L/D seems spot on
     
  15. SPASKIS

    SPASKIS Registered

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    In a serious debate, saying that the other, who provided telemetry figures, is wrong without providing any single evidence and calling bullshit to his claims is quite quite arrogant if you ask me.

    You could have used the standard setup coming with the car to prove him wrong, but no, you decided to talk about your super setup and how secret it was that you cannot even show a picture of the telemetry for tire load at a given speed.

    I'll check myself tonight and give my opinion providing some pictures of telemetry results.
     
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  16. mclarenf1papa

    mclarenf1papa Registered

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    First of all: "That having been said, I'm not hugely familiar with the telemetry output in RF2, so I could very well be missing something with the aero"

    Secondly, a screenshot like I posted (even with just ride heights and aero numbers) isn't going to tell anyone anything about your team's sacred setup.

    Thirdly, we're both correct. The testing I did was, as noted, with the default configuration of the car (i.e. high downforce). If you run a very low setup that can't physically be run IRL due to the underfloor skid plate regulations, you can max it out at about a 3.7 L/D. Realistic setups are in the 3.3-3.4 range.

    The setup your team made is undoubtedly for the low drag version of the car, which I've just tried with the same setup as in my HDF test and found it to max out at a 5.05 L/D.

    To that end, the low downforce version of the car is fine. However, the gap in efficiency between it and the high downforce package makes zero sense. It adds 1000N of downforce for 1000N of drag at 150 mph. If that was the case in real life, every single team would run the low drag configuration at every single race. The LMPs I've worked with have all had very comparable L/Ds between their LDF and HDF configurations. So there's certainly still a fairly major issue with the car unless, as I've proposed, the telemetry isn't logging correctly.

    So, thank you for your incorrect accusations about my "incorrect logs," it's much appreciated.
     
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  17. Devin

    Devin Member

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    Actually there is a good reason for that. This guy wouldn't stop spamming the rF2 discord and I am on my laptop, on which I only have access to already existing logs from the team. More tests have to wait. But even then, we have noticed some problems with the default setup having very low downforce for some reason, so that part actually matters.

    Doesn't matter if the setup is sacred or not, I am simply not allowed to share it. That includes logs created from it. And no matter how irrelevant the data may seem, that doesn't change the fact that I'm not allowed.

    That particular log could well be from the low downforce version, I will have to check that. However, you claimed that the car generally has a very low L/D ratio and instead of contacting S397 about it, you decided to start a shitstorm instead before even asking anyone in particular for help with the log results.

    No matter how right you may seem, there is *never* a reason to start a shitstorm and cause people to spam every place related to the game.

    I will look at more logs when I have time to see if I can confirm your claims about the HDF configuration. But as my past experience stands with this car, the HDF setup seemed quite similar. Not in terms of logs, but I roughly remember top speeds and downforce in certain situations that would suggest that it must be somewhat close to correct.
     
  18. avenger82

    avenger82 Registered

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    Contact @Marcel Offermans, they will look at this. This is best way to get constructive results from this discussion.
     
  19. mclarenf1papa

    mclarenf1papa Registered

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    Been in contact with Marcel; it will be looked into.

    edit: and the issue seems to be with the "standard aero package," so all but the low drag trim are affected.
     
    Last edited: Jun 25, 2018
  20. Christopher Elliott

    Christopher Elliott Administrator Staff Member

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    Keep it civil or don't post in here.
     
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