[SOLVED] Strange slipstream effect when a car is FOLLOWING me

Discussion in 'Technical & Support' started by Eric Moinet, Jul 18, 2017.

  1. kimbo

    kimbo Registered

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    In a straight line if the car that goes behind is close enough to the car ahead, it loses aerodynamic load,
    This is how it happens in real life
     
  2. Eric Moinet

    Eric Moinet Registered

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    That's not the issue : I am the one ahead, I am the one losing control.
    And the car behind is not so close on me but at about 50/200 meters/yards
     
  3. kimbo

    kimbo Registered

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    And this is what i said ,the car ahead, loses aerodynamic load , not only the car behind, but only when it is close enough
     
  4. Eric Moinet

    Eric Moinet Registered

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    Ah ok, sorry I've misunderstood you. In that case I agree with you, we can see that in Nascar for instance where they use it to gain a draft/drag advantage. My problem is that I am so far ahead it couldn't happen.
     
  5. kimbo

    kimbo Registered

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    Yes, I agree, 50 meters is too far for me too.
     
  6. SPASKIS

    SPASKIS Registered

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    For what I know you need to be very close to the car ahead in order to reduce the depression that is created in the back of the car due to the turbulent flow. Providing continuity to the flow eliminates those vortices but I understand that you need to be less than 1 meter from the car ahead in order to notice its effect that can be quite noticeable when cars are touching.
     
  7. kimbo

    kimbo Registered

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    Yes, it must be very close, i do not know the exact number, but very close.
     
    Last edited: Aug 8, 2017
  8. Eric Moinet

    Eric Moinet Registered

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    Hello again,
    Short update after the holidays, it seems I've sorted it out :)

    I made a test today with another computer and hadn't experienced that inverted slipstream effect after two intensive sessions on different tracks and cars. I can also say that the car is more stable when dealing with traffic, which was also an issue in retrospect. So definitively something wrong with my computer.

    I suspect the culprit being that my Win 7 is on a virtual hard drive, and thus the virtual memory getting its hands full and no more room for the game. Well, now I'll have to reinstall everything on my rig :rolleyes: And test again before stating it's solved.

    I'd like to thank everyone who gave a bit of their spare time to help me, especially Lazza, Spaskis but also CamiloNino who, despite his disbelief, pointed me to the right direction saying nobody has ever experienced this. Thanks guys.
     
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  9. Lazza

    Lazza Registered

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    Thanks for the update, here's hoping your (enjoyable, I'm sure :D) reinstall gets things going smoothly on your main machine :)
     
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  10. SPASKIS

    SPASKIS Registered

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    Glad to read that you solved it.
    Thanks for the feedback!
     
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  11. Miro

    Miro Registered

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    If drafting numbers are not correctly applied it can have some nasty effects on the leading car. Even if fine tuned, as mentioned by Spaskis above, at some corners if the fallowing car is very very close and the leading car allready at the limit of adhesion you might experience a diffuser stall for example.
    A good corner example would be T3 at Istanbul or even Blanchimont in rain.
    On the other hand it is also possible if the numbers are somewhat of that the leading car even gets some understeer.
     
    Last edited: Sep 6, 2017
  12. Eric Moinet

    Eric Moinet Registered

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    Hi all,

    A short update after two months following the new system install and enough racing to make an assessment.

    So, the issue is definitively sorted out for rF1 which is great, but NOT sorted out for rF2 yet, still losing control of the car when someone is behind me, as in losing the rear end (in a turn or when applying the brakes), or running wide as if I was pushed by the car behind.

    When pressing Ctrl-C I can see the purple bar going 2/3 which is rather new I believe, maybe one update or two (it was a good half before), so maybe it's hardware related, but in that case I'm very surprised to be the only one to suffer from this very issue as I believe I'm well into the specified hardware recommendations. Anyway, if someone can point me out on which hardware can be out of range it will be much appreciated. Thanks a lot.

    AMD Phenom II 965 x4
    8GB RAM
    AMD radeon rx 550 4GB vRAM
     
  13. Postipate

    Postipate Registered

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    What is your FPS when somebody is following you? If your fps drop too much, driving would become too hard. Your specs are very poor for rF2. Would not be suprised if you have under 30 fps, and its way too low.
     
  14. Bernd

    Bernd Registered

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    Looking at your computer specs, i would suggest to try the 'Aggressive Threading' option, that has a checkbox in the video settings window.
    Maybe that improves the things.
     
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  15. Eric Moinet

    Eric Moinet Registered

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    Not that much I believe, though I don't really have the time to check when it gets messy :p. But as far as I could check there wasn't a massive FPS drop. And definitively not below 30 FPS.

    Thanks for the tip, will try that.

    @both (and others) can you elaborate on my specs so that I know what to do to improve it. Thanks a lot.
     
  16. stonec

    stonec Member

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    Well your CPU is very old, but it might not necessarily be a problem, especially if you don't add 20+ AI cars. The more AI cars, the more CPU usage. The CPU only becomes a problem when the purple bar gets very close to 100%. So I would advice you to follow that purple bar while you are driving, because it may quickly peak to 100% and then fall back again, in which case it's still a problem.
     
  17. Eric Moinet

    Eric Moinet Registered

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    Thanks Stonec. Online race and we average 10/12 people on track usually, sometimes a bit more but anyway, yesterday we were 12 online and I couldn't lap the GTs without running wide for several turns before being 'out of the zone' and safe. And as far as I can control it the purple bar was circa 60/70% not near 100%, but as I said before it's hard to control it in race while your struggling with the car so I might have missed something as well.

    What annoys me is that, although the CPU is 6/7 year old it should be powerful enough and is in the range of the recommended specs, and as far as I know, people with an older, less powerful CPU can play with no issue.
     
  18. Lazza

    Lazza Registered

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    My quad core has the purple bar up around 70-80% consistently, and depending on track and background processes I've occasionally hit slow motion. I still didn't feel any effect from someone being behind me. No idea what's going on.
     
  19. Eric Moinet

    Eric Moinet Registered

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    Thanks Lazza, good to know. I don't have a clue either but it's there.

    I wouldn't say it's slow motion, nor stuttering for the matter. I can see what slow motion and stuttering are when I add a bunch of AIs for training, but that's not that.

    It is, simply put, the rear end sliding when it shouldn't, or a sort of massive push from the car behind in a zone of about 50 metres/yards. So basically what we would expect from a slipstream but inverted : a push instead of a pull and rear end instead of front end losing grip.
     
  20. stonec

    stonec Member

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    I watched again the replay video of Norisring that you made few months ago. In my honest opinion, in the video you gave I see small mistakes almost every lap and many spins and half spins, sometimes with a car close behind, sometimes not. When I look at the video, the first thing it tells me is that you struggle with braking on the Flat6 mod. Your braking point to turn 2 on lap 8 (the last lap you spun) was over 15 meters later than on lap 7, which was the primary cause of the spin. It also looks like you possibly struggle with brake balance and brake heating. If the brake ducts are set too low, the brake distance becomes longer as the brakes heat, which tends to get worse lap by lap. And brake bias being set too rearwads typically cause the rear to lose traction in heavy brakings, like I saw in that video. Flat6 is one of the more difficult mods on braking, so it may not be the best car to test this issue with.

    It's possible that there is a CPU usage issue behind, but I can't see any pattern to it. What I see is braking points and driving lines that are not consistent and a car that is not set up well.
     
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