[asheshouse]

As Spitfire13 says, make a new folder root\MODS
and in MODS make sub folder STD ----- root\MODS\STD
and out the main aircraft folder into root\MODS -- example: root\MODS\SpitfireMk1

various files need to be copied from root/files into the STD folder, retaining the same subfolder structure
These are:
com\maddox\il2\objects\air.ini
i18n\plane_ru.properties
i18n\weapons_ru.properties

Then you need to add text to each of these files as per this example using the SpitfireMk1

ADD TO air.ini
SpitfireMk1 air.SPITFIRE1 1 NOINFO gb01 SUMMER

ADD TO plane_ru.properties
SpitfireMk1 Spitfire MK.1, 1939

ADD TO weapons_ru.properties
#####################################################################
# Spitfire Mk.1
#####################################################################
SpitfireMk1.default Default
SpitfireMk1.none Empty

Add skins subfolder in root\PaintSchemes\Skins
Example:
PaintSchemes\Skins\SpitfireMk1

When you run the game the program will search for air.ini and the other files and use the first copy it finds. It looks in MODS first, files second, *.sfs files third. So you can keep your original HSFX files safe in root\files in case you want to use them. If you want to disable the new mods then rename MODS to -MODS, and the program will revert to reading the original HSFX files.

Hope this helps

Ashe