Questions about slot and slotless motors

I would like to ask a question about brushless motors.
Anyone could answer me the followings?

What is the difference between a slot and slotless brushless motor?
What are the pros and cons between them?
Among the brushless motors in the market, which brand is a slot motor and which brand is a slotless motor?
As I know, a slot brushless motor runs cooler than a slotless motor inherently. Is that right?

Thank you.

[crazyjr]

I'm sure someone will correct me, if i'm wrong. Slot designs have sort of a iron core that the windings go around ansd slotless is a design where the windings are pressed into the can without support of the iron core. Slot designs are usually handwound (I think) and usually more expensive. To tell the difference, the slot will feel like a brushed motor( where the magnet seems to grab the end of the slot and kind of has a jerky motion, Slotless will have a very smooth feel like there are no magnets in it. I have both and i can tell you, If you can swing it, get the slotted and an esc that can handle it, you won't be dissappointed

[BrianG]

Like Carzjr said; a slotted motor has windings wrapped around iron (usually laminated) cores. A non-slotted motor is basically a "basket" of wire inserted into a cylinder core and the wires don't wrap around a core.

I would think a slotted design would be better since it concentrates the magnetic fields and thus increases torque. But this page seems to think otherwise. What they say seems to make sense about the cogg-free characteristics since both Neus and IIRC Novak use slotted motors and those have issues on the MM. They also say that slotless motors can be more efficient ( heat up less), are smoother running, etc. I wonder if Neu motors would be better if they were slotless while maintaining the higher end quality? I guess then they would be Lehner. : )

[zeropointbug]

Yes, I too know slotted and slotless motors as what you two describe... I on the other hand know that there have been some crazy efficient (98.5%) using slotless design. To me, it kinda makes sense that it would be more efficient. IMO

But as far as motors available, yes the Lehners are slotless (i think), as well as most motors like Feigao's, etc. The Neu's are slotted, like Brian said... the Lehenrs and Neu seem to be equal as far as power and efficiency goes on a per weight basis.

[BrianG]

Ever feel the difference between a Neu and a Feigao just by spinning the shaft with your fingers? On the Neu, you can REALLY feel the magnetic detents. I just assumed slotted would be better since the magnetic field seems to be far more concentrated. OTOH: A slotless design has a wider magnetic field (since it isn't concentrated by a core) so it makes sense that the power delivery would be smoother. It also makes sense that some ESCs would have issues with a slotted motor since the back EMF pulses are much more intense.

Also, coreless coils don't saturate magnetically as easily and are more linear, which is why coreless inductors are used in high-end audio crossovers.

[crazyjr]

Cool i got one ;) Yes Brian, the novaks are slotted

I was told a slot motor has larger torque than a slotless motor and hence slot motor has lower kv than slotless motor in the same condition.
A iron core in a slot motor not only acts as a magnet filed amplifier but also a large heat capacitor which can lessen temperture increase.
Both solt and slotless motors exist in the RC market.I think they may some com
plementary pros and cons. Manufactures should have some reasons to use solt or slotless motor.