If you fly on HL and you have 4.05 but you want to fly 4.04 I have a VERY simple solution.
Most people that have been around this game a while already have a full back up of thier previous version and can switch through HL path. But that also takes up valuable Hard drive space. My FB folder is around 3gb! But....there is a solution.
FIRST THING TO DO IS TO BACK UP ANY FILES I MENTION HERE....JUST IN CASE! But don't get excited, we will only be messing with 2 files.
This will enable you to play Version 4.04m and 4.05m from the SAME install with a simple double click of the mouse. You will not have to change paths in HL or have 2 installs of the game.
1. Read THIS THREAD by Luthier on how to back up to your original IL2.exe and IL2FB.exe files. You must have the 4.04 files installed and NOT the new ones from Ubi.
2. Download the following 2 batch files to your main fb 4.05 folder. Then create shortcuts to them on your desktop.
Big props to Sparx at the War Clouds server for doing these batch files for me, thanks man.
4.04 batch file
4.05 batch file
3. Now, make a copy of your 4.05 "files.sfs" file which is found in your main FB directory. Name that copy to files.405 and leave it in your main IL2fb directory.
4. Now find your 4.04 files.sfs file. You can find it in your patch you downloaded. Hopefully you still have it. Copy the file and rename it files.404 and paste it into your main IL2fb folder.
Your done! You should now have files.404, files.405, files.sfs, 404.bat and 405.bat in your main IL2fb directory and 2 shortcuts to the .bat files on your desktop.
Now, if you double click on the 404.bat shortcut and start the game, it should say version 4.04.
Close the game and double click on 405.bat and start the game, it should say version 4.05!
Now you can switch back and forth at will.
Hope this helps some folks!