There are 2 separate axis systems in play for an airplane in maneuvering
flight. The first axis is the is the aerodynamic axis system acting though
the cg in the relative wind direction, and the other is the inertia axis
acting through the cg lined up with [front and back] mass elements [...]
...if the inertia axis is inclined to the aerodynamic axis for some
reason [...] the 2 axis systems are not aligned. [...] a pitch moment
can be produced, and its the coupling [...] that constitutes an inertia
coupling.

Thanks. That makes it much clearer to me.

If I'm banked, and I "pitch up", does that mean the nose rises up with
respect to the horizon, or with respect to the pilot's feet?

Jose
--
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