Last idea was to do a downgrade to 2.4... that of course did work and now I can fly my F15 again.
I am still learning and do not play online yet so this "fix" is ok for me at the moment but it is sad because I was going to get the Viggen as my first full sim plane right now... and Mirage and Tiger and Mig-21...
Guess I will wait to see if there is a fix, wanted to start multiplayer career with F15 anyways :(