Knowing your Spitfire can be really handy. As swiss has pointed out with the IL2 Compare tool... the LF versions of Spitfires are generally meant for lower attitudes.
With the Mark V this means that the aircraft is best between 0 and 3000 meters. Above that and performance seriously declines, whereas the F.Vb is constantly increasing it's maximum top speed up to around 6000 meters. So depending on your application you will want to choose the appropriate fighter.
With the IX version things get more complicated.
The LF.IX versions are "lower altitude", however, the history is a bit different. With the LF.IX the supercharger settings were changed so as to make the IX faster than the captured FW190A-4 that the RAF had at all altitudes. The F.IX Spitfire is only faster at some altitudes and not others. We don't have a F.IX right now so all Spitfire IX's are LF models....
Except the HF.IXe which I see a lot of online. The HF.IXe is not faster than the LF model until somewhere around 8000 meters. But yet I see tons of HF models flying on servers at altitudes of 500 meters and never climbing above 2000 meters.
So now you have a leg up
