Originally Posted by DavidN
Current kills is correct and comes from the secondary power equation P=IČ x R.
This is derived from P = I x V
So if I keep current constant but increase voltage. It will still burn up the motor as it is the waste heat that does it....
Nope, it won't burn, losses in the copperwire will remain the same, as per the first equation you gave. Just more power to the prop due to higher rpm.
However, hysteris losses in the stator go up linearly with rpm ('=' voltage) and eddy current losses in the stator go up squared with rpm. At high rpm thinner (currently 0,2mm is standard) and better quality steel statorlaminations must be used.