On a wing, the cp is slightly behind the cg. Cg is measured from 1/3 the leading edge of the wing. All wt and balence are measurements are taken from the datum line.
Does this apply to rockets below <0.7~ Mach? Either way "The long slender body" in question has stabilizer fins that are probably far outside of the Mach shadow(?)
I never thought of the center of mass acting as the pivot point. As soon as that was mentioned it all clicked into place in my head and I finally understood why it needs to be in front of the CP. Question. If the CP is definitely behind the center of mass, is it possible for the rocket to flip? I have a small Loc model rocket that flew perfectly on A thru C motors, but then one day just started flipping across the launch area shortly after leaving the rod. The only thing that was different was the batch of C motors I was using. I even tried adding more weight to the nose and it would still spiral/flip. I do not want to test it anymore due to the dangerous flights but it has been eating me up ever since and no one at my rocket club could explain why it flew fine in the past but no longer works.
Maybe something got damaged and misaligned and created lift somewhere along the body , and when the force from lift increased it further worsened the instability. Or Motor misaligned for same reason?