[HFAlex]

I can't find the file air.ini. Where is it located?
Cheers

[Condor345]

It should be like this

...IL-2 Sturmovik 1946\MODS\STD\com\maddox\il2\objects

[asheshouse]

In some installations it is here.

..IL-2 Sturmovik 1946\Files\com\maddox\il2\objects

Ensure there is only one of them.

Before installing any new aircraft install new buttons file which comes with Aircraft Installer --- currently version 3.5 Backup the old buttons file first. Always use the latest version. It does not matter if you do not have all the aircraft installed.
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Ensure the game still loads correctly. If not then you probably have the wrong buttons version.

Only when you are sure that the game still works with the new buttons file should you install the new aircraft.

[HFAlex]

:x :x
I don't have the file in any folder.... hock:

[asheshouse]

If you have not yet installed any mods then start with the Unified Installer
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Its a long download but the wait is worthwhile.
This will install your MODS folder within which will be the air.ini

Alternatively, if you already have mods installed, there is a default air.ini provided with the Spitfire Mk1.
This was one of the first, if not the first, new slot aircraft.
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Use this with Aircraft Installer v3.5 as linked in previous post.

If using this check that you have all the aircraft listed in the air.ini actually installed, otherwise the game will crash.