"So by MO 's logic, maintaining a constant airspeed and altitude 45 deg banked turn would require continual changes of power throughout each 360 deg turned , these depending on the windspeed.
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Yup, and that's what kills his argument. MO can argue all he wants, but if his assumptions are incorrect (i.e. we are talking about a particular reference frame, he is mixing two) then no matter how great his logic and maths, it still isn't right.
It doesn't matter how many degrees you have of what patches you wear - the logical argument based upon correct assumptions is always going to triumph (thank goodness).