Tina wrote in
:

It is NOT that simple.

Allow me to put an external force, applied with an elevator or a
thruster or an engine and I can turn it around any center you choose,
including one external to the airframe.

Tell us, please, where is the center of rotation in an airplane
flying a loop?

Where is the center of rotation of the orbitor, flying nose first, as
it circles the earth at constant altitude and attitude relative to
the local horizon?

One of the principles underlying scientific 'theory' is, if one
example show the theory is flawed, it's the theory, not the
observation, that should be abandoned.

I submit the center of rotation of the airplane flying the loop is the
center of the loop, and the center of rotation of the orbitor is some
4000 miles from its center of gravity. I'd appreciate knowing the
flaws in these examples.

I'd love to meet the guy who can fly a loop that round!

The center of rotation will be around the CG of the airplane.
That doesn't mean that if, for example, the airplane were in a spin, that
the center line of the rotation will be around the CG. It won't. But the
airplane is still, nonetheless, rotating on it's CG.
It's what the CG "is"


Bertie