I can't say I've ever meet any famous astronauts or test pilots that I'm aware of anyway. On the other hand I've meet and shook hands with a few kings, queens, princes, princesses, Congressmen, celebrities, and the like... Not that they would remember me.
I've never seen you use the X-15 as an avatar. I kinda' like the one I posted if you want to use it. I generally don't use planes, ships, automobiles and the like.