My second model: Mini Motor

Hi,

I understand that no ferromagnetic material around the stator's (inductor's) winding helps lowering the weight of the motor, but because of that the flux density is much weaker, so the efficiency of the motor is lower.
For a flight test of few minutes the usage of the battery (Lithium DC source) is not that important, but if you want to have the flying object usable for extended periods, the efficiency of motor is important.

This does not target the motor shown in this topic. All motors presented under this website have in common no ferromagnetic path for the inductor.
Otherwise, I appreciate how the website's authors detailed the building of the motor with so many construction steps.

Hi!

I am sorry that I did not answer.

I understand what you mean, ferromagnetic core increases the magnetic flux of the coil.

I also thought about it, but concluded:

That the presence of the core in the coil is effective only for relatively slow-speed electric motor.

In my designs (and not only mine) motors operate at 40 000 rev / min. and more. Metal simply do not have time to remagnetize so fast and because of this motor is extremely inefficient. Probably worth a closer look at this material as a ferrite, but it needs to dramatically change the design of the engine. And in the processing the ferrite material is very uncomfortable.

Perhaps you've had experience on manufacturing of micromotors with a ferromagnetic core?

If so, I was glad to learn more about it.



By the way time of flight model: my latest project, it's a plane weighing up to 2 grams, with the motor without the ferromagnetic core, however, the time of flight is 15 minutes and more! This indicates the high efficiency motor.