Hey, you're welcome for the explanation, but you are in no means at all wrong by saying 7,000 meters. That is just circa what it was in IL-2 1946 because the atmosphere was always the same. You'd get contrails in IL-2 because of the height you were flying at, not because of the surrounding air. So you could very well get contrails at 7000 meters, if it's cold enough :)


For the interested, here's showing that not only wingtips create vortices :)

Flap during typical humid day:

http://www.youtube.com/watch?v=TXDPCINTFKA

And this is why you need carburettor heaters :P

http://www.youtube.com/watch?v=TFYzHfjTGtk

That stuff would ice up really fast if it wasn't heated

Typical propellers also create vortices :)

http://www.youtube.com/watch?v=_g1SInGmRv0

Nice posts, thank you.