It would also be nice (although not critical) if someone could look into the reason why IL-2 blurs terrain textures so much. I think it's basically texture mip mapping LOD Bias being set at too close a distance, which causes the game to reduce the terrain texture resolution at far too close a distance - this is especially evident with the view zoomed in, you can see the far terrain gets sort of pixellated and blurred look...
I've been trying out 2048 map textures and this last has also at times puzzled me. You can use a very detailed 2048 texture but, when flying over it, it does not necessarily look that more detailed, even up close.
But, when flying in mountains and very hilly terrain, you do seem to notice quite a lot more detail.
I have been pondering this and think it may have to do with the angle that the textures are viewed at.
When flying over flat terrain, from a cockpit you look at the terrain from almost perpendicular angles, you are looking down at angles of maybe 5, 10, 15 degrees perhaps. When flying in mountains, from a cockpit you can often look at mountainsides at an almost true 90 angle, that is straight head on.
When you look at 90 degrees, then a texture is not really deformed so much, as you are looking much as you would on your screen in a graphics program.
When looked at in 10 degrees,I think the game tries to render an average of all the details and colors in a texture and ends up creating a more smudged and blurred version of the texture.
You could try to approximate this by for instance holding a bookcover and looking at it straight on. Then hold it almost flat at 180 and see how much you can make out of the words and details in any photos or illustrations on the cover.
I think is one of the reasons why - at least up to a point - Il-2 maps of mountainous or hilly terrain, usually look better than simple flat terrain. Even with old 1024/ 512 texture maps.