real road and real life

Discussion in 'General Discussion' started by Flaux, Oct 30, 2015.

  1. Euskotracks

    Euskotracks Registered

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    Some facts about real road technology:

    - Real road simply increases the grip level depending on the amount of rubber laid.
    - A green track will directly use the grip level as defined in the tdf file.
    - A full rubbered track will increase this grip level by about 17%.
    - For an average track this will represent a much smaller time gain which will depend on the track and car.
    - Track temperature does nothing regarding grip levels.

    This facts have been obtained after testing. The description of the tests and results are described hereafter:

    - Selected track: ISI Montecarlo 2.00
    - Selected car: ISI Corvette C6R 1.62
    - All tests made switching control to AI. No Tire Wear. No Fuel Usage.
    - 40-45 timed laps per stint at accelerated time.

    Case 1: Green preset, Static realroad time scale.
    Average laptime 1:27.3 - Best laptime: 1:27,1

    Case 2: Saturated preset, 15x realroad time scale (just in case it was not saturated enough)
    Average laptime 1:25.3 - Best laptime: 1:25,1

    Case 3: No real road*. TDF grip factor 1.00 (the original value)
    Average laptime 1:27.3 - Best laptime: 1:27,1

    Case 4: No real road*. TDF grip factor 1.17** (after some iterations)
    Average laptime 1:25.3 - Best laptime: 1:25,1

    *In order to deactivate real road I had to create an update of the track renaming racesurfaceXX.gmt to acesurfacXX.gmt (without the "r") for all racesurface instances. This way, the road simply uses the grip factor as defined within the tdf and unaffected by RR. I did check that setting real road to green or saturated had no effect in laptimes.
    **Another update, similar to the above, was required but with a modified tdf

    As you see, a 17% grip increase "only" improves laptimes by 2,3%. This will vary depending on the track and car. As a gneeral rule, the higher the throttle usage the smaller the grip related time gain effect. 100% throttle usage (junior karts at indy) should show no gain :)

    For testing track temperature effect, I took the latest case which was at 29ºC sunny and tested both 0ºC and 60ºC with absolutely no impact in average and best laptimes. The in-garage display showed the specified temperature for both track and ambient.


    My personal analysis of the facts exposed in the thread:

    - Considering that the laptime of the tests is relatively similar to the laptime this weekend in Mexico GP, the 6 second improvement between P1 and Q3 would mean that grip probably increased by 35-40% more or less. It should be noted that probably 1,5 seconds of those are simply justified by the larger amount of fuel used in P1 and less close to the limit lap and not only by grip.

    - Such a big increase cannot be explained by rubber depositing on a track. The reason for it, is the presence of oil emerging from the freshly laid asphalt. However, oil is not simulated at all in rF2 real road technology and therefore rF2 has not been programmed to simulate what actually happened in Mexico. If you check other tracks of the F1 calendar, the typical difference P1-Q3 is slightly over 3 seconds. Considering the same 1,5 seconds for fuel and further from the limit driving, this would imply around a 2 second grip effect for rubbered asphalt. This is the same difference between a green and full rubbered track in rF2 for a 90 second laptime. Good job ISI!

    - It should be noted that despite not being simulated it would be nice addon, especially for simulating oil spills after two cars crashing and staying there for several laps. IMO real road technology should be able to account for the following variables per node which would all affect tire grip, tire temperature and tire wear: rubber, water level, oil, dust, dirt, marbles and temperature. Water level (in mm) should replace actual % which makes absolutely no physical sense to me. A simple option to be able to better fine tune this would be the possibility to increase the full rubbered grip increase with respect to the reference value in the tdf. I calculated a 17%

    - In rF2, a green track is the condition that happens after heavy rain washes out the laid rubber. Nothing more or nothing less. In a real track that should be the condition at the beginning of the race weekend if the track is not much used. It is very likely in that case that since last time used, several rainfalls have occurred. Those people saying that green track represents a strange and particular condition that barely happens are completely misunderstanding the concept.

    - They may be right, however, saying that for some particular track (or maybe for all of them) the green track grip level is adjusted too low (the one defined in the tdf as has been proven). I can see that most tracks are using 1.00 as default grip value. Maybe this value is a bit too low and hence the driving on ice perception that is so much criticized. I can't say because I don't have any data to support. It should be noted that if increased, the full rubbered grip would increase accordingly, causing some people saying that rF2 is like driving on rails :)

    - For sure, none of those extreme opinions will be supported by any evidence. People simply love talking for talking using their intuition and subjective opinions. Telemetry is for freaks! It is curious to see that when arguing if green track is too slippery or not, barely nobody mentions that it cannot be actually fully affirmed or denied considering track temperature is not taken into account and that it should make a significant difference in laptimes and tire behaviour. Cooler asphalt is reported to be more grippy than a hotter one which causes oil emerging to the surface (beware that tire temperature needs to be correct in order to take full advantage of it).

    I hope someone found it interesting
     
    Last edited by a moderator: Nov 3, 2015
  2. argo0

    argo0 Registered

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    Very. Thanks.

    Sent from my SM-N9005 using Tapatalk
     
  3. peterchen

    peterchen Registered

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    Chapeau Eusko!!!
    Great post!!
    Thank you very much!
     
  4. Eddy

    Eddy Registered

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    Yup Eusko, that was very interesting tyvm
     
  5. Euskotracks

    Euskotracks Registered

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    I forgot to add one thing:

    The tests have been carried over using AI as stated.
    Otherwise I wouldn't have been able to do them due to the huge amount of testing involved and the lack of repeatability of human driving.

    This brings up the fact that tire temperature is not simulated when AI is driving.
    This is not a problem for calculating the 17% road grip increase effect but can affect the laptime gain effect.
    I would expect a higher tire temperature for a faster lap with a higher grip due to the larger heat input power.
    This temperature change will also provoke a change in grip of the tire itself which will affect the laptime.
    To summarize it, a global friction could be established as the combination of the tire relative friction with respect to temperature and the track grip condition.



    Whether if this helps or not will depend on whether new temp is closer or further from optimum tire temperature.
    Hence, if these same tests are performed driving instead of using AI, they could show greater or lower time differences.
    The reported two second difference between green and fully rubbered track could be slightly bigger or smaller depending on the setup and driving style

    When I also said that track temps didn't affect grip, I was not considering either tire temperature effect, which might be considered in the tire thermal model.
    I would expect a tire temperature increase for being in contact with a hotter surface which reduces the cooling effect.
    However, I am not sure whether this track temperature effect on tire cooling is being actually simulated. I haven't actually tested it.
    This should be easy to check by driving a few constant time laps under extreme conditions of 0º and 60º and comparing telemetry.
    I will check this when I am on my wheel unless someone reports it previously.

    Considering all these, the estimation of the 35-40% grip increase would comprise both track grip and tire grip effects.
    Considering that it was clearly stated throughout the weekend that the tyres were too hard, it is very likely that they worked with a better temperature with a rubbered and faster track. Consequently, both factors would be acting in the same direction of increasing grip. Lets' say 10-15 % of the total was due to better tire temperature and the remaining 25% due to better track grip. For sure it is a wild guess since I have no tire temp data.

    Tire temps have shown a very unrealistic thermal behavior under rain and a very doubtful one under normal conditions.
    This makes me seriously doubt about rF2 tire thermal model accuracy. I do think, however, that the mechanical tire model is excellent.

    But that is a different story. I just wanted to point out that tire temp effect on grip hadn't been taken into account in my tests and how could this influence the results when they are considered.
     
    Last edited by a moderator: Nov 4, 2015
  6. Lazza

    Lazza Registered

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    Can I ask where you get the 17% from?

    *Crap, sorry, AI and therefore TBC file. No idea what's normally in those...
     
  7. Euskotracks

    Euskotracks Registered

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    Should I understand that you already unserstood how I got it?

    It seems that you answered yourself but I don't see that the post has been edited so I am not sure...

    Enviado desde mi SM-G130HN mediante Tapatalk
     

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