Virtually there - I think we are virtually there on agreeing. Thank you, for clarifying your position.
BTW, if you'd actually read my posts, you'd realise that I completely agree with everyone else that there is absolutely no discernible difference in airspeed (induced drag aside) when turning in any direction in a constant airmass
This is the key point in this thread discussion.
"Masses have inertia", that is a better way to say it, then talk about "inertial masses". "Inertial frames of reference" is the best way of saying it.
. . but that doesn't mean there is no difference.
Yes you are right. But the differences you are referring to are the ones due to relativity, and the relativistic adjustments aren't going to be the cause of a stall in a Mallard.
ps (I have a BSc in physics)