Sigh, its been done although very badly.
Download world war 2 online.
It is a plane, navy and ground warfare sim all rolled into one.
Graphics are a bit dated but it has it's moments.
It is not a game i would recommend though, but if you want to see what could be given resources and a keen developer then take a look.
But if it is warfare strategy and flight sim then fly an IL2 SEOW campaign.
There are plenty of squadrons who take part in online SEOW wars including ours. You get to ground plan, and then fly.
A lot of anti-ground (mud) missions are normally flown.
In our current campaign I managed to land sixty plus tank, arty and infantry divisions behind enemy lines which clears me to capture at least two control points.
Google SEOW for more info on what the mod is we use.
http://69giap.com