Repeatedly, I read main problem in flight sims ground mapping is that its world is flat.

This doesn't allow to correctly model real layout, actual routes, etc.

I wonder why it isn't modeled a new "curved" world, replacing current flat maps surface with sort of spherical cap as a basis for correct texture.

I do not mean only for IL-2, but at least for all new sims.

Any programmer out there that could explain?

Thanks,
GB

The pain and effort involved in modeling a curved Earth just isn't worth the gain. Yes, factually, the world underneath you is actually curved, but when the total curvature is less than you can detect, why bother modeling it?

I believe Warfare sims models a curved Earth for the strategic implications (controlling fleets thousands of miles apart). It would be interesting if they're modeling a spherical Earth or a J2 ellipsoid or something even more accurate, but when it comes down to individual aircraft, ground vehicles, and naval units, a flat Earth is close 'nuff. Even on a flat Earth you can model the appropriate distortion of the longitude lines, though, so I prefer it when developers go past the chessboard model.