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

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

  1. stonec

    stonec Member

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    Forgot one thing, I recorded quickly a video where you miss the braking point with a car behind. Look closely at the brake pedal input on bottom of screen. At first you apply brakes slowly to 75%, but then in middle of braking zone you start to reduce brake input and at t=4 seconds your brake input is less than 20%. Then as your car starts to run wide and miss the corner, you go back 75% on the brakes. In this one instance problem is inconsistent brake pedal usage.

     
  2. Eric Moinet

    Eric Moinet Registered

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    Thanks for your input Stonec (will look at the video tonight at home).
    As you said it's probably not the best car for such a test. That and the bumpiness of the track and so on. I take what you say, it's all good info to improve myself.
    I'd probably better put another video from a better race so people can take a look only to what I think is the problem rather than a full bag of crappy laps.
     
  3. SPASKIS

    SPASKIS Registered

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    Norisring is indeed very bumpy in some versions (to the point of being almost unplayable). 3 years ago I converted one of the rF1 versions to use it in our DTM championship. The original track didn't have the road modeled as rF2 needs which provoked a very bumpy result. I spent hours flattening nodes to get a final poor result. I have later seen better conversions if you like this track.

    However, in order to check for the item in question use a different track where braking is not such an issue due to the irregularities provoking tire lockups.
     
  4. Eric Moinet

    Eric Moinet Registered

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    That's indeed an rF1 conversion but not sure if it's yours or not :D
    As for the video I'm for sure at fault there. I can't recall it accurately but I think there was a bump on the braking point there and I was hitting the wall if braking too hard, hence the pedal easing. But as said before not the best choice to show the issue in retrospect.

    Anyway, I'll post a new video tomorrow with some better examples of the problem I suffer from (too late now, go to dodo)
     
  5. Eric Moinet

    Eric Moinet Registered

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    Morning all!

    So here's the last race I ran this week-end.
    Replay file from server I'm third on the grid, not the car with the focus on : https://www.mediafire.com/file/92nbo5e2pn35jr4/RC%20ELMS%20Rd6%20Algarve.rar
    Motec files : http://www.mediafire.com/file/h6stp3z3s1pch8y/Portimao.zip
    Track : Portimao - Autódromo Internacional do Algarve v1.11 by odb: https://steamcommunity.com/sharedfiles/filedetails/?id=1131107775
    Mod is EnduRacers

    For those willing to help and give their input please take a look at the following points :
    Lap 12 (TimeStamp 1343.xxx)
    Lap 44 (TimeStamp 4534.xxx)
    Lap 46 (TimeStamp 4924.xxx)
    Lap 52 (TimeStamp 5487.xxx)

    Please ignore Lap 10 accident (I drove over a kerb and hit some invisible object there : broken suspension o_O) as well as Lap 45 which is my usual one-brain-freeze-per-race issue. I'm afraid you can't fix anything for this one.

    As always, thanks a lot for the help.
     
  6. Eric Moinet

    Eric Moinet Registered

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    Hello! Did any one take the ticket ?
    I know it's a three-year old problem so there is no hurry and I can live with it by now, but I just wanted to know if there was any of you on it.
     
  7. Daniele Vidimari

    Daniele Vidimari Registered

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    I'll take a look, replay downloaded :)
     
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  8. Daniele Vidimari

    Daniele Vidimari Registered

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    Here my point of view:

    1) too wide, too much steering angle, more brakes than usual & aggressive downshift
    2) very aggressive downshift in 1st gear
    3) you missed the apex and then go full throttle too early
    4) braked too late, aggressive downshift

    Nothing strange for me here!
     
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  9. stonec

    stonec Member

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    Lap 12) Releasing brake pedal too soon, quite aggressive turn-in
    Lap 44) I see nothing much weird. You release brake pedal early and speed doesn't decrease as much as expected, hence slight oversteer at apex.
    Lap 46) It looks like your line is very different from previous lap, more on the outside and steering angle is too low
    Lap 52) You keep throttle on 25% through the entire corner. On lap 51 and 53 you release throttle fully on apex. So running wide is IMO because you kept throttle on.

    I can't say for sure that nothing is wrong with rF2, but I see a bit of the same mistakes as in your previous video with releasing brake pedal too early and engine screaming from engine braking.
     
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  10. Eric Moinet

    Eric Moinet Registered

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    Thank you very much for your input guys, I'll have a look at it.

    That said:
    You're pointing the consequences there, that I already know. What interest me is/are the cause(s). Not that I disregard your saying, it is very valuable at thank you to take the time to have a look at the files. But what I would found even more valuable would be to understand why it happens when someone is behind not any other time (bar the usual odd mistakes).

    Thinking of it, it might as well be because my front wheels are blocking in that cases because of the 'dirty air flow', but definitively something I'll have to address in the coming races, as well as the aggressive downshift. They are on top of my list now, thanks for that.
     
  11. Daniele Vidimari

    Daniele Vidimari Registered

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    By "too wide" in the 1st point i don't mean the apex, but your braking line IMO is wrong, is too wide, too late and too "bent" (sorry i can't find a proper name in english). In addition, as @stonec said you released the brake too early and in the same time you did the aggressive downshift in 2nd gear.

    I had a race in Portimao last week, and i saw a lot of drivers do the same line in that turn, that IMO is wrong, because when you downshift in 2nd gear you are already steering, that cause oversteer (or understeer, it's car-related).
    Contrariwise, if you brake a bit early and straightened you will able to put the 2nd gear BEFORE the corner, eat the apex and double your exit speed.

    In conclusion try to be a bit more smooth and determinate with each input, and a lot of time is better to brake 3 meters before than 1 after (Portimao is a big example, Indianapolis is another) :)
     
    Last edited: Nov 11, 2017
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  12. Eric Moinet

    Eric Moinet Registered

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    Thanks I will check that.
    But I think I did the same every lap (will check that too I'm far from sure) and only went to a spin when I had someone behind me (or too wide over the border the second time) which is the point of my topic here. If it was a random spin or off track I wouldn't mind (I have too but not that often, and I know why every time), but as it happens quite each time there is someone behind me "in the zone" I have a concern.

    Thanks anyway much appreciated.
    (You can add Monaco for the 3 meters thing :) )
     
  13. Lazza

    Lazza Registered

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    I can't see anything in the tyre or aero loads to indicate anything unusual compared to other laps.

    What is evident is quite a variation in laptimes through the entire race, and a lap to lap variation in tyre temperatures to go with that, meaning that not only is it difficult to judge lap to lap because of the inconsistency, but that inconsistency itself may well be the root cause here.

    If you bring up a speed trace for a lap in i2Pro, and then flick through the next laps with similar times (you can press N on the keyboard to go to the next lap, there's also a toolbar button to do the same), in 'time' mode (toggle between time and distance with F9), you can see that the corners are all moving around quite a bit in terms of laptime, and it's also clear that at least a couple of corners are being driven differently at times. To be frank, and at risk of sounding hypocritical because my own driving wouldn't be any better, but it's not hypocrisy because I can see it with my own driving too :D , I think you're just not driving consistently enough. With more reliable laptimes and corner speeds you would find it easier to isolate what the issue is when it happens, but I suspect you'd find there is no longer an issue.
     
  14. stonec

    stonec Member

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    One other possibility may be that your problems with car behind is due to distraction. It may not even be visual distraction, it can be the sound from the car behind mixing with your own engine sound. If I can't hear my own revs it will affect my lap time. For example if I turn sounds entirely off and drive based on visual input only, I'm almost certain I will switch gears and brake slightly differently, because I don't have my usual reference points in rpm sounds.
     
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  15. Eric Moinet

    Eric Moinet Registered

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    Well, I've been reviewing the whole replay with your sayings in mind and I can't see anything in my driving really different in the 4 mentioned laps than for the rest of the race. Inconsistencies for sure but not anything drastically different from the other laps to make me lose control only when there's a car behind. Don't get me wrong, your inputs are all very valuable to improve my driving style, but I get that it could be difficult, if only possible, to track a physical load with a video or Motec file. Because there is indeed a load, some kind of FFB input that deludes me for a fraction of time and ends with a spin, a missing apex or a slight slide in the best case.

    Stonec I understand the distraction thing so that the issue I have is that I have an issue with the issue (Wait, say it again !). It surely plays a role in it (like "Oh dear, yet another a car behind me, I will drive into problems"). But this doesn't apply when I don't have any clue at all of someone closing on me, and I could give endless examples of it happening. Sorry, no disrespect to you and as said your help was useful anyway.

    So be it. At this point I'm afraid we can't track down the issue further more considering we can't track it with external files. I guess I'll have to live with it until I change rig or quit out of frustration. I'd like to thank all of you for the help and all the time you've given me to try and troubleshoot the issue. Very much appreciated mates.
     
  16. Eric Moinet

    Eric Moinet Registered

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    So... Sorted ! (so far)

    What I did ?
    Unplugged the steering wheel from the front pannel USB plug and plugged it to one of the rear panel USBs.
    No more trouble when someone is following me (so far).
     
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  17. Mike Crimlis

    Mike Crimlis Registered

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    Just so Eric knows he is not going crazy, I have also had this issue.
    The car suddenly behaves unexpectedly different to previous laps and as I go off the track/hit something/lose time, I see a car go past which was obviously close behind at the time of the incident.
    I have mirrors enabled but don't use them (I'm a white van man...) so it's nothing to do with psychology/pressure.

    I recently changed from rear USB port to a front one because the front ones are USB3. There was no change when I did that.

    My PC is:
    AMD A10-6700 APU with Radeon(tm) HD Graphics @ 3.70 Ghz 8136 MB
    Windows 7 service pack 1 build 7601
    Nvidia GeForce GTX645 4011 MB (Triple monitor)
    Video driver v10.18.0013.6881
    Directx 9.0c (4.09.00.0904)

    I also have an issue whereby the steering will suddenly jolt and the handling then becomes terrible until I reset by hitting escape to enter the pits. Almost like getting a puncture but Trackmap doesn't show any great variation in pressures. I have Mechanical Failures turned off so it's not suspension breaking or anything like that. I've even had this happen when leaving the pits!!

    Mike.
     
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  18. Eric Moinet

    Eric Moinet Registered

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    I know I'm not crazy :D
    I liked your post 'cos it's good to know I'm not the only one to suffer from that. What you describe is exactly the same as I had. I hope you'll find a way to fix it for you, or maybe people willing to help in the good way.
     

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