Originally Posted by Ron van Sommeren
Might be a good idea to put your double/triple stator torque/power/#wind/force explanation here too. Very instructive
Here you go:
Originally Posted by KreAture
adding more iron like that increases the max wattage you can stuff into the motor before the iron is saturated with the magnetic flux created by the coils. Basically, it increases the max power-handling of the motor.
Not just straight so easy. It can increase the max torque achieved by the motor. The torqque will be square to to the stator lenght. Torque easy tranclates to magnetic force between stator and rotor.
In example in twice longer stator you can get twice more MF at the same saturation level but at the same time you can use longer magnets in the twice longer rotor. So the force will be 4 times stronger.
How it translates to power? At the same number of turns you can run twice more current before stator is saturated (this is the part of twice stonger MF from stator). So the power at the given voltage is just twice bigger than in single. But wait, the torque is 4 times stronger, so it must be lower rpm. Yes. Kv of that motor will be 2 times lower.
So how to bring it back to the original Kv (and original rpm)? Use twice less turns. But wait again - you need again twice more amps to get the the saturation level.
So now we have motor that is twice longer with twice longer magnets, with half of original turns (and probably thicker wire) and drawing 4 times more current. It runs the same rpm and delivers 4 times higher torque.
Isn't it slick?