You accually did say center of mass. but somehow it got screwed up between when it entered my brain and when it came back out. sorry. and maybe the cendter of mass might be in the middle of the X-wing, probably not though. because think if you spin it, the fixed point ( thanks for the link Alreech
) would be near the back to balance/evenly distribute the mass.
or maybe it would be like spinning an egg, in the sense that there is more mass at one side and not the other and spinn off in some weird way
I'm not too good at this type of stuff though, so I may be totally wrong.