How to manually add new SU10 ground friction variables

[meurkel]

Hi,

I could not wait until the next PMDG update so I went ahead and added the variables manually. Luckily, FBW have already created a pull request with the new variables and values they found realistic. All I did was copy those parameters to the bottom of the flight_model.cfg of the PMDG under [Flight Tuning]. If you want to find out more about new variables, check the sdk documentation. In short, the variables allow you to set how much the stickiness of the wheels decreases with speed and to prevent cross wind from being cancelled out. Without the crosswind variables set to the respective values crosswind is cancelled out at first and added gradually as you speed up which is not realistic at all. Overall, I found the ground handling during take off and landing to be much improved and I very much hope PMDG will add these natively very soon. Until then you can do what I did and paste these lines in the flight_model.cfg at the very bottom:

ground_crosswind_effect_zero_speed=-1000
ground_crosswind_effect_max_speed=-1000
ground_high_speed_steeringwheel_static_friction_sc alar=1
ground_high_speed_otherwheel_static_friction_scala r=1

Again, the values are from FlyByWire since I couldn't be bothered to do my own testing but everybody is welcome to play around with friction variables. The crosswind ones are already set such that crosswind is never cancelled out. I hope this is useful and have fun,

[Boeing 25-01]

Giving it a whirl.

[spesimen]

oh wow, thanks! had no idea this is something that could be setup manually. gonna try this on the dc-6 too

cheers,-andy crosby

[HDR10]

Interesting idea.

X Plane does this much better than MSFS.

[737NG4EVER]

Thanks very much Mark, this is very good news, finally, with some tweak, we could get closer to the center line and recreate crosswind landings more realistically. Thanks again for sharing.

[Falcon99]

Backup the original before making changes.

[ram1220]

Can someone please tell me where that flight_model.cfg file is located? I am having a really hard time finding it. Thanks.


Edit I found it. Finally.

[macc1966]

Can someone please tell me where that flight_model.cfg file is located? I am having a really hard time finding it. Thanks.


Edit I found it. Finally.

[Drive Letter]\[Root of your MSFS Directory]\Community\pmdg-aircraft-738\SimObjects\Airplanes\PMDG 737-800

[fernando.boeing]

For someone who has already tested and understands a little more about the SDK, do you have any other suggestions on the values established by FBW?

[meurkel]

I can't test any changes to the values properly since I'm not a real pilot. I hope Emi and the other members of the tech team give PMDG enough input to find the best values. All I can say is that it feels a lot more realistic now, which makes sense since the variables resemble real physical effects.

[Falcon99]

FBW is not PMDG and only the PMDG Devs could let us know the effects of changing these values. Hence my suggestion to ensure you backed up before changing anything.

Changing these values without PMDG guidance is experimenting and at your own risk. Proceed accordingly.

[meurkel]

I did back up everything. Don't worry.

[PositiveZero]

I don't think that there is much risk. The first two parameters - ground_crosswind_effect_zero_speed and ground_crosswind_effect_max_speed - if set to -1000, tell the sim to never cancel out the effect of crosswind. The second two - ground_high_speed_steeringwheel_static_friction_sc alar and ground_high_speed_otherwheel_static_friction_scala r - specify how much the tires will resist lateral movement. 1 is the default value, so specifying 1 in the config file has the same effect as not specifying it - in other words it is not changing anything.

[Crabby]

So why is everyone so excited about mucking with the cfg file to after all the fumbling, change nothing? This is getting worse than wing wobble/flex. I am asking seriously though because I cannot understand this.

[meurkel]

Because a lot of people have reported it's gotten better. Please note, because the crosswind is not cancelled out anymore you need more yoke forward pressure to counter a strong crosswind at low speeds. I think that's what people forget to do or are not used to.

[Crabby]

I think most people don't want to take the time to learn to fly the thing and are trying to tweak their own errors/inability out of the flight model, or make the changes to their controllers (curves, use of external systems for controller control etc).

[macc1966]

I don't think that there is much risk. The first two parameters - ground_crosswind_effect_zero_speed and ground_crosswind_effect_max_speed - if set to -1000, tell the sim to never cancel out the effect of crosswind. The second two - ground_high_speed_steeringwheel_static_friction_sc alar and ground_high_speed_otherwheel_static_friction_scala r - specify how much the tires will resist lateral movement. 1 is the default value, so specifying 1 in the config file has the same effect as not specifying it - in other words it is not changing anything.

I tend to agree with Charles. I tested these variables and values with my 737-800 and didn't notice any improvement regarding aircraft sideways movement on ground, that is, the aircraft continues to randomly drift sometimes to the left others to the right during take-off and landing roll, requiring constant and vigorous rudder correction.
To be honest, I must say that this behavior is previous to SU10, so I think that the implementation of wind gusts neither improved nor worsened things.

[PositiveZero]

I think that crosswinds in the sim have improved. I think that the issue you are seeing is because the values of 1 for ground_high_speed_steeringwheel_static_friction_sc alar and ground_high_speed_otherwheel_static_friction_scala r, don't change anything. It is still to be seen if better values are entered for those parameters, if it will make ground handling realistic.

[Want2BFlyin]

Quick question for those who have tried this suggested edit and aren't satisfied with the results. Did you copy/paste the entries as provided by the OP? It looks like there may be some unintended spaces in there which may be preventing this from working.

[PositiveZero]

The spaces seem to have to do with posting them here. I tried to remove the spaces in the post, and they are always put back. In the config file I ensured that there were no spaces.

[meurkel]

To all those who say nothing changed with the edit, did you test in a strong crosswind?

[macc1966]

To all those who say nothing changed with the edit, did you test in a strong crosswind?

Well, if in calm wind conditions or with no wind at all, I'm frequently struggling to keep the aircraft aligned with the runway centerline, can you imagine what it would be in the presence of strong crosswinds???
For me the key point is not to have crosswind, or gusts, or even hurricanes. The point is that it would be nice if the aircraft had a decent ground behavior, taking in good account the tire-to-ground friction effect.
But, as this was already mentioned several times earlier, it's a problem with MSFS, not with PMDG specifically.

[ram1220]

I tried the OP's fix and I did see an improvement. Thanks for the suggestion.

[JRBarrett]

I would like to remind everyone that when dealing with a crosswind - either on landing or takeoff - rudder alone is not sufficient. You must use aileron as well - deflected into the wind.

[meurkel]

And also yoke forward pressure at low speeds. Otherwise, the nosewheel is steering is not effective enough.

[737NG4EVER]

Hi,

I could not wait until the next PMDG update so I went ahead and added the variables manually. Luckily, FBW have already created a pull request with the new variables and values they found realistic. All I did was copy those parameters to the bottom of the flight_model.cfg of the PMDG under [Flight Tuning]. If you want to find out more about new variables, check the sdk documentation. In short, the variables allow you to set how much the stickiness of the wheels decreases with speed and to prevent cross wind from being cancelled out. Without the crosswind variables set to the respective values crosswind is cancelled out at first and added gradually as you speed up which is not realistic at all. Overall, I found the ground handling during take off and landing to be much improved and I very much hope PMDG will add these natively very soon. Until then you can do what I did and paste these lines in the flight_model.cfg at the very bottom:

ground_crosswind_effect_zero_speed=-1000
ground_crosswind_effect_max_speed=-1000
ground_high_speed_steeringwheel_static_friction_sc alar=1
ground_high_speed_otherwheel_static_friction_scala r=1

Again, the values are from FlyByWire since I couldn't be bothered to do my own testing but everybody is welcome to play around with friction variables. The crosswind ones are already set such that crosswind is never cancelled out. I hope this is useful and have fun,

Hi Mark, are these supposed to have the space there? scala (a space) then r=1

ground_high_speed_steeringwheel_static_friction_sc alar=1
ground_high_speed_otherwheel_static_friction_scala r=1

[Want2BFlyin]

The response to the same question I asked earlier in the thread: https://forum.pmdg.com/forum/main-fo...890#post218890

[737NG4EVER]

Thanks man

[jjeffreys]

No when you apply it you need to remove the space, when I first tried it I thought that it was not working, it works great after the space is removed. I plan to spend a little time this weekend adjusting to see if I can find some numbers that suit me better. From what I understand 1=100% so I am going to try 1.25 and so on.

[meurkel]

Sorry about the space. Don't know how it got there. I'll see if I can edit my original post.

Edit: I tried to correct it but for some reason it won't save my edit. Instead, it introduced another space where it doesn't belong. Never thought a forum page coud be so buggy. There are supposed to be no spaces in the name of the variables.

[737NG4EVER]

Sorry about the space. Don't know how it got there. I'll see if I can edit my original post.

Edit: I tried to correct it but for some reason it won't save my edit. Instead, it introduced another space where it doesn't belong. Never thought a forum page coud be so buggy. There are supposed to be no spaces in the name of the variables.

I feel you, yesterday I tried to edit the title of a post i created, there was no way.

[FinalLight]

i'll give this a try as well

[Trovis]

Does anyone know what is the range of values of the "ground_high_speed_otherwheel_static_friction_scal a r" and
"ground_high_speed_steeringwheel_static_friction_s c alar"?

And what do the high and low values mean?

[meurkel]

Have a look in the sdk documentation. I also gave a brief summary at the top of the topic.

[Trovis]

Where is the SDK documentation? Doy you know the answers of my questions? Thanks.

[meurkel]

I have to say I'm a bit frustrated after the last update. The new variables are still not in the flight_model.cfg. Come on PMDG, the Fenix feels so much better on the ground. How is this not prioritized enough?

[Vlad Tepes]

I have to say I'm a bit frustrated after the last update. The new variables are still not in the flight_model.cfg. Come on PMDG, the Fenix feels so much better on the ground. How is this not prioritized enough?

Try this, please. I think that it will solve your issue.

[FLIGHT_TUNING]


ground_crosswind_effect_zero_speed = 15
ground_crosswind_effect_max_speed = 240
ground_high_speed_otherwheel_static_friction_scala r = 0.61
ground_high_speed_steeringwheel_static_friction_sc alar = 1.25

Oh, make sure that you change scala r to scalar and the second from sc alar to scalar again. I don't know why is not showing correctly.

[meurkel]

Oh thanks. How did you get these values since they're not the default ones?

[Vlad Tepes]

Mark, I will keep it very short. As was mentioned the information is in SDK narrative, additional each airplane will react differently to the wind, for example, in a small-mid size aircraft like 737 you will notice a reaction due to the x-wind component somewhere starting from 7 - 8 kts, that will translate to approximately 15 ft/sec. In this way, anything below that value will be no factor, above that the airplane will react and gradually increase the effect up to 100% up to that (arbitrarily) 240 speed. You can lower that 240 to whatever value you like, but it will become more aggressive.
SDK info is here flight_model.cfg (flightsimulator.com) and conversion from KTS to Ft/sec is here convert ft/sec to kts - Search (bing.com).

[Boeing 25-01]

Try this, please. I think that it will solve your issue.

[FLIGHT_TUNING]


ground_crosswind_effect_zero_speed = 15
ground_crosswind_effect_max_speed = 240
ground_high_speed_otherwheel_static_friction_scala r = 0.61
ground_high_speed_steeringwheel_static_friction_sc alar = 1.25

Oh, make sure that you change scala r to scalar and the second from sc alar to scalar again. I don't know why is not showing correctly.

I will give these a try, thank you for proving the figures.

Will any of this change the amount of thrust needed to start moving? I still find the ground friction too high to get rolling, and takes too much thrust to keep moving at 20-25. Also the nosewheel steering with tiller is too aggressive out of neutral. These may not but I did want to mention this ground handling behavior to add to the discussion.

Thank you!

[Vlad Tepes]

I will give these a try, thank you for proving the figures.

Will any of this change the amount of thrust needed to start moving? I still find the ground friction too high to get rolling, and takes too much thrust to keep moving at 20-25. Also, the nosewheel steering with tiller is too aggressive out of neutral. These may not but I did want to mention this ground-handling behavior to add to the discussion.

Thank you!

No, it will not. Agree, ground friction needs to be adjusted.
Regarding the nosewheel steering, which needs an overhaul, it is not accurate, you can find a few posts of mine where I explained the issue.

[meurkel]

It's actually realistic as per the real thing. You need quite a bit of thrust to get moving but then it keeps rolling with idle thrust

[Fabristunt]

I resume this thread to ask if PMDG is planning to add these values sometimes in the future? I don't want to modify myself the aircraft.cfg file and currently it's still very hard to control the aircraft even with slight crosswind ...