although it would steal a bit of the "grand feeling" of a 3D battle like for example in DS9, one could think of combining multiple ships of the same class into a small enough number adding up their stats respectively.
I guess it would not be possible to just use the setvisible flag (=False) for each ship which is out of current camera sight so it would not be rendered in effect? Sure there's a problem with collision and weapon fire then because of the missing mesh. But Irrlicht seems to support 2D replacement graphics.
At larger view when zooming out, these graphics could be used too. It would look more like our current bote graphical combat view in the simulator then but well, one cannot have everything

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I believe Galciv does the same. When zooming out enough, only 2D pics are shown. Rotating them to the right angle is an easy job. At least TrommlBomml already implemented this in Direct3D for our new galaxy map view for next bote alpha.