By default, the game(s) will only list 4:3 aspect ratio resolutions; these only available when the engine was designed and built. You need to edit the
config.ini to set widescreen resolutions or use a utility such as IL-2 Shturmovik Stab or IL-2 Manager.
Note: Every time you run the game IL-2 Setup module, the resolutions will be reset to 4:3 aspect. This is one reason why the utilities are better; you do not need to run the game IL-2 Setup again. You only need to run the game setup module after the game and patches are initially installed.
i.e.
1. Install game
2. Install patches
3. Run IL-2 Setup
4. Run game and create a player. Set sound and video options. Make sure PERFECT mode is selected and then exit
5. Install IL-2 Shturmovik Stab or IL-2 Manager (do not confuse with IL-2 MAT Manager)
6. Enjoy
IL-2 Shturmovik Stab is good as common widescreen resolutions are provided. It will also automatically detect if your game installed is patched sufficiently to support the widescreen resolutions; not an issue for 1946 but some of the earlier series needed to be patched to a certain level to use them and the original game did not support at all. If you have one that is not listed, you can simply add it to the list! Simple.
Besides, it keeps fixing Dart's attempt at configuration!?!

What more proof do you need...
Disclaimer: I am the author of Stab so I am totally biased!