Still puzzled about it. Is the aerodynamic moment a "theoretical" thing?
¿Can we use any point of reference we want?
No, it is very real
Yes, but it is usual to use 25% mean aerodynamic chord in the wind tunnel and aircraft CG for anything else
Let's assume an airplane with the CG exactly in (i.e. at) the CP, in trim, steady level flight. How much tail lift does it have? How much is the ANU moment it has to balance? Does it depend on what point we choose for the moments? That would make no sense...
Tail lift = zero (at zero thrust)
Dunno - what is ANU moment?
When I think of a moment, I think of a force and an arm. Moments will vary depending on the point selected, of course. When talking about the aerodynamic center, Where is the force?
Lift force effectively acts at the centre of pressure as always
CliveL