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Fix for rudder problems


JNelson

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For those of you who have a problem with the rudder in the yak being far too much to the left and having no need for left rudder on takeoff. This is due to the trim tabs that ED has implemented. They are not editable from the menu however you can edit them in your game files.

 

You need to navigate inside your game install DCS World/Mods/aircraft/Yak-51/FM/FMOptions.lua

 

Inside this file you will find several lines.

 

aileronTrimTab = 0.0

elevatorTrimTab = 0.0

rudderTrimTab = -0.666

 

This -0.666 is the root of your problems. For a perfectly trimmed aircraft in the roll and yaw at 250 kmph (80% RPM and 600mm) I have found these settings for aileron and rudder.

 

Edit: Turns out my joystick was uncalibrated so aileronTrimTab should equal 0.0, not -0.13.

 

aileronTrimTab = 0.0

rudderTrimTab = -0.25

 

(for some reason the aileron trim tab is inverted negative value means right whereas positive means left)

 

This file appears to be loaded between flying sessions so you can use the instant action mission freeflight to tune your aircraft to your desired trim.

 

Lastly this file will be overwritten each update so it's best to use something like JSGME to make it a mod.

 

Hope this helps.


Edited by JNelson
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I have some issues editing the .lua files and it doesn't work, would you be so kind to attach here your FMOptions.lua

Thanks

 

I recommend using notepad++. It's free makes things like this easier. Turns out my original post my joystick was uncalibrated so the aileron trim should be zero.

 

Attached the lua with zero aileron trim and the correct rudder trim.

FMOptions.lua

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Thanks for the fix.

 

 

It has cured the rudder offset, but it doesn't seem to do anything with regards to the takeoff assist or reduced yaw moment.

 

 

I have tried setting the values relating to autotrim and takeoff assist to 0, but that didn't change anything, and I can't use the keyboard to use the rudder, despite no controller being bound in the controls.

 

 

I'm impressed ED somehow managed to break a plane with nothing more than wings and an engine.

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Thanks for the fix.

 

 

It has cured the rudder offset, but it doesn't seem to do anything with regards to the takeoff assist or reduced yaw moment.

 

 

I have tried setting the values relating to autotrim and takeoff assist to 0, but that didn't change anything, and I can't use the keyboard to use the rudder, despite no controller being bound in the controls.

 

 

I'm impressed ED somehow managed to break a plane with nothing more than wings and an engine.

 

I do have to put in left rudder with the correct trim settings however it was much less than at launch this may have been due to the fact the aircraft was not trimmed at launch. Eg if you set the trim of the rudder to zero it will take a fair amount to compensate for the moment. So I'm not really sure what is accurate.

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I recommend using notepad++. It's free makes things like this easier. Turns out my original post my joystick was uncalibrated so the aileron trim should be zero.

 

Attached the lua with zero aileron trim and the correct rudder trim.

 

I used Notepad but somehow after takeoff the rudder return to the offset position, I will try with your file and report here, thanks.

 

Edit: I've tried again but no luck, even with your .lua file it doesn't work for me.


Edited by Mig Fulcrum
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Maybe I am misunderstanding, but you can adjust the Aileron and Rudder Trim on the Options menu.

 

In February "Mig Fulcrum" said :

 

Rudder is still deflecting to the left and the trim tabs on the "special menu" don't seem to work.

 

This is a work around for that.

 

Though "AcroGimp" has said :

 

I tried with the stock settings and the recommended setting in the Rudder Fix thread on ED Forums, neither are remotely correct IMO compared to my Yak. This was Sim not Game, Takeoff Assistance was off.

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The deflection to the left is meant to be there according to the team, I am seeing a difference when using the trim tabs.

 

There must be a difference between ours and their build then because the trim tabs going end to end make no noticeable difference.

 

Furthermore every aircraft I've flown has been trimmed for the cruise speed. Neutral rudder required at cruise. In the yak a lot of right rudder must be applied which is not consistent with this. As you can imagine holding a lot of right rudder in is not particularly fun in the cruise, especially when going far.

 

The numbers I edit in the lua file make the trim correct with a trimmed aircraft around the cruise speed.

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  • 6 months later...
  • 2 weeks later...

My FMOptions.LUA settings

 

aileronTrimTab = 0.02

elevatorTrimTab = 0.0

rudderTrimTab = -0.25

 

I'm also going to play around the with the rolling resistance as the aircraft accelerates on tarmac with minimum throttle (setting around 35 manifold pressure gauge) with generator still working.

 

Maybe this is how the real Yak-52 works, but at this stage its more annoying than anything having to constantly ride the brakes.


Edited by panzerd18
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thanks, works nicely, what would you tweak for the rolling resistance?

 

mainWheelRollFricK = 0.022

mainWheelGlideFricK = 0.69

 

mainWheelRollFricK = 0.044

 

Much easier to taxi without overspeeding at minimum manifold pressure keeping the generator going.

 

Although ED might have modelled it correctly with 0.022 as another member of the forum with real Yak-52 experience said you had to get on the brakes.

 

Try 0.044 and see what you think.

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  • 1 year later...
On 4/25/2021 at 12:17 PM, gomslork said:

The special options trim setting still do nothing. At least editing the fmoptions makes it a bit easier to fly

This, ED can we please get this addressed? It has gone on for years - the problem is that the trim tab options in the special options don't do anything - the rudder trim tab stays at -0.666 in the FMoptions.lua regardless of what it's set to in the special options (also would it be possible to add this setting to the ground crew menu?).

Pleased to know that it can still be adjusted via the FMOptions.lua (which is located in Mods -> Yak-52 FM if anybody is wondering). 


Edited by Northstar98
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  • 5 months later...

Sorry, I need to push this topic, because the rudder issue is the only thing putting me off so far in a plane I otherwise (surprise!) really love since I picked it up a few days ago!

 

Edit: helped myself with an edited .lua and ovgme…


Edited by Hiob
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"Muß ich denn jedes Mal, wenn ich sauge oder saugblase den Schlauchstecker in die Schlauchnut schieben?"

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On 10/16/2021 at 10:08 AM, Hiob said:

Sorry, I need to push this topic, because the rudder issue is the only thing putting me off so far in a plane I otherwise (surprise!) really love since I picked it up a few days ago!

 

Edit: helped myself with an edited .lua and ovgme…

 

Can you attach your lua file so i can check it out myself please 🙂


Edited by Bagpipe
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20 minutes ago, Bagpipe said:

Can you attach your lua file so i can check it out myself please 🙂

 

Yeah, sure - here you go:

(the zip contains the ovgme ready path)

YAK Rudder.7z FMOptions.lua

you can adjust the value for trim easily by yourself, if mine doesnt suit you. You find the values in line 58-60.


Edited by Hiob
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"Muß ich denn jedes Mal, wenn ich sauge oder saugblase den Schlauchstecker in die Schlauchnut schieben?"

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