lol, ok, i'd love to help, but you've gotto be able to do a bit better than 'i think' for which version you are running.
are you using a selector to start your game, or the SAS il2fb.exe with the red star/blue background icon?
what does the game say in the bottom-left corner when it loads?
i could go on about your installation procedure first, but this is probably not the best thread for that.
you're right in that new planes for sas modact 3 should go in the #SAS folder, and their air entries go in the cohabiting STD folder...
so what exactly is happening?
your game isn't crashing, it loads, but you just don't see the new planes, is that it?
that means that your game is not loading the modact 3 version, but most likely the UP version.
...which takes me back to my first question...