Magnet dimensions

[GriffinRU]

1% is only for magnet.
While motor Total efficiency from min to max RPM varies from 0-100%. So if in our best range this variation only 10-20% (way lower then magnet contribution) then motor runs cool. But if it is 40% spread then we are in trouble.
I do accept yours and everybody’s input as good and real data. And always accept fact that math on paper stays on paper, but real world is real. But if we start talking about high-end stuff, let’s be familiar and try to understand what we can feel and what we can measure.
One thing which I mentioned earlier but somehow it slipped away, utilizing segmented magnets allow reduce air gap with less penalty in Eddy Current losses. And that’s helps achieve efficiency in low and middle range.
And you correct 100% about efficiency sensitivity of Hacker/Feigao motors to particular RPM based on Kv.

Artur