Hi Flanker,
Here's the link to version 4.11:
http://forum.1cpublishing.eu/showthread.php?t=29039
As for patching up to this from your friends version I really don't know. You can pick up a new copy of 1946 (v4.07) from ebay/amazon for about £5. Might just be easier to do that.
I had the exact same issue with my mate I persuaded to get into flight sim last year...he had to get a new disc.