... Kv does not affect heat for a given load.
True if the "load" is given as an absolute torque.
In my example related to the load is given as a
percentage of stall torque.
Another point is that low turn motors, at least the ones I checked, can handle much less load (percentage of maximum at regular voltage) before exceeding the nominal maximum acceptable current limit.
If you have more power available you're likely going to use at least some of that extra power, which I assume is the main reason users that switch to more powerful motors experience them getting hot.
That's what my "observation" is all about:
Low turn motors get hotter because users typically pull more power from them, making the comparison at same load percentage is somewhat relevant.
The 17.5T motor at 7.4V and stall (100% load) draws 8.5 times the rated maximum current.
The 3.5T motor at 7.4V and stall by comparison draws 42.5 times the rated maximum current. To draw only 8.5 times the maximum current the load can only be 19.7%.
(Since the voltage here is constant the power drawn is directly proportional to the currents.)
I meant to say that the cross section per turn is exponential, ...
You
did say that, but the cross section per turn is linear. One turn use 1/1 of the total cross section. Two turns use 1/2 each, three turns use 1/3, and so on.
Then the length of wire is roughly multiplied by the number of turns.
Resistance thus proportional to the number of turns squared.
