[Boris The Spider]

For any plane at this point use the 3.8 AC Installer. It has every current mod plane in it.
As XB-49 said, the "wrapper" is in the UI install. I've never installed one since I got the UI1.1 file installed.

Then download the plane of your choice.
Follow the ReadMe/Installation Instructions to the letter.

In general you will take these steps to install a new plane:

1. Unzip/open the .RaR file to a temporary folder on your desktop.
2. Open that folder and examine the contents. Open any ReadMe or Installation files and read them.
3. Place the plane folder in your MODS folder
4. Copy/Paste the appropriate lines into the following files per the instructions of the author;
* "X":\Program Files\Ubisoft\IL-2 Sturmovik 1946\MODS\STD\com\maddox\il2\objects\air.ini,
* "X":\Program Files\Ubisoft\IL-2 Sturmovik 1946\MODS\STD\i18n\plane_ru.properties
* "X":\Program Files\Ubisoft\IL-2 Sturmovik 1946\MODS\STD\i18n\weapons_ru.properties

("X" is the drive you put your mod install on, typically the 'C' drive.)

This process has worked flawlessly for me so far.
For me the key has always been to read any informational/instructional files first.

This may not work for every plane or mod but it seems to be the most common way.

Again; READ THE README/INSTALLATION FILES FIRST!

Hope this helps.