I live in Charlotte, and know where the museum is. I have driven up to it but didn't go in. I will some day perhaps if they ever open the airport over look again I can make a day out of it. It's so frustrating that the spot is closed down now. I used to go and watch planes all the time, now I don't bother because there isn't any other good spots.
If you want to see the museum you can get there from several different directions. From either direction on Billy Graham PKWY turn onto Morris Field Ave. (driving from the North will be a right turn, from the south a left) Turn Right onto Airport Dr. and follow signs for Carolinas Aviation Museum. It will be on your left. You can't miss it once you get close because of all the old planes sitting out side.
If your a visitor to Charlotte and are leaving from the main terminal, follow the exit signs and turn right onto Airport Dr. The museum will be on your right.