Jul 01, 2007, 06:53 AM
Registered User
Discussion

6 or 12 magnets


I'm embarking on making a 20mm* 10mm stator based motor to turn a 5*5 prop for my TT Velocity...

It has been suggested I use half of the usual number of magnets to up the kv of the motor...

Usually we shoot for 80% coverage of the flux ring?? so do I use 6 mags as suggested and ignore the 80% or do I use 12 mags in a NNSSNNSSNNSS config or some other suggestion?
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Jul 01, 2007, 07:57 AM
.
edited
Last edited by prinz; Nov 10, 2008 at 01:23 PM.
Jul 01, 2007, 08:49 AM
Master of 1 point landing
Quote:
Originally Posted by Chippie
I'm embarking on making a 20mm* 10mm stator based motor to turn a 5*5 prop for my TT Velocity...

It has been suggested I use half of the usual number of magnets to up the kv of the motor...

Usually we shoot for 80% coverage of the flux ring?? so do I use 6 mags as suggested and ignore the 80% or do I use 12 mags in a NNSSNNSSNNSS config or some other suggestion?
what prinz says is sort of true. There is some efficient gains using NNSSNN in the GB motors Ive built. Additionally, the NSNSNS motor I have has some issues starting on my eflite esc - I have to use CC with a timing change.
Jul 01, 2007, 11:30 AM
Registered User
stegla's Avatar
I'm using 12 magnets as 6 poles for high-revving EDF stuff and have found it much more efficient than 6 magnets.

Steve
Jul 01, 2007, 12:04 PM
.
edited
Last edited by prinz; Nov 10, 2008 at 01:23 PM.
Jul 01, 2007, 02:04 PM
jj1
jj1
Registered User
jj1's Avatar
CC, would like to see it too..
Once tested a 6 pole motor first with 6 mags then adding another set of 6 (NNSSNN...)
and keeping everything else the same. Didnt take exact measurements but IIRC the gain of the additional magnets was very small.
-JJ
Jul 01, 2007, 03:44 PM
Flying motor mount master
fly_boy99's Avatar
This is due to the two sets of magnets being put together being larger than the stator head. Which makes using single mags for 6 poles start easier. I've had much better results in using 6mags instead of 12 NNSS....

Again it depends on the width of your mags though...

Quote:
Originally Posted by ImaBiggles
what prinz says is sort of true. There is some efficient gains using NNSSNN in the GB motors Ive built. Additionally, the NSNSNS motor I have has some issues starting on my eflite esc - I have to use CC with a timing change.
Jul 01, 2007, 04:11 PM
Master of 1 point landing
I think it the thickness of the flux ring (rotor) also has a part to play in it. If your flux is skinny - extra mags may not help. If your flux it think (like the komodo) you might benefit from doubling up. Regardless, the gain is minimal and I really dont think it will a practicle dif UNLESS you are running a very heavy load.
Jul 03, 2007, 01:21 PM
Registered User
stegla's Avatar
Quote:
Originally Posted by prinz
steve,
if you have hard data about your finding,
please post it.

PRINZ
Sorry............I made some other changes to the motors in question at the same time, namely, I changed from multiple strands of thin wire to a single thick wire.
So I have no real proof that NNSSNN gave me a leap in efficiency .

Steve
Jul 04, 2007, 10:58 PM
Night Flying
Ron H's Avatar
Quote:
Originally Posted by ImaBiggles
I think it the thickness of the flux ring (rotor) also has a part to play in it. If your flux is skinny - extra mags may not help. If your flux it think (like the komodo) you might benefit from doubling up. Regardless, the gain is minimal and I really dont think it will a practicle dif UNLESS you are running a very heavy load.
I think it is more due to the stator head v magnet width. I get good results when the magnets are the same or smaller than the heads, but see no improvement using pairs when one of the pair can reach one tooth while the other is still on the last one.

On a side note, a 20mm motor will run much cooler with 6 mags rather than 12, which means more watts can be used.
Jul 06, 2007, 02:13 PM
Master of 1 point landing
Quote:
Originally Posted by Ron H

On a side note, a 20mm motor will run much cooler with 6 mags rather than 12, which means more watts can be used.
Why would you get an efficiency gain with 6 v 12 mags? If thats the case, they winner would be clear. Thats rather the opposite of what I saw on my GBv 12 v 6 may test (single stator 6 winds/22awg)
Jul 06, 2007, 10:56 PM
Night Flying
Ron H's Avatar
Cooler running motors can handle more watts in, because the magnets act as a fan and pull over the stator. A 20mm with 6 mags will have more air movement fom the can than a 12. The gain is all about gearing and letting the motor rev. The deadset DD guys will never get it.
Jul 23, 2007, 08:02 AM
Registered User
stegla's Avatar
Just a thought?

Is it possible that , at high rpm, timing and switching from the ESC is made less critical by having NNSSNNSSNNSS instead of N S N S N S?

I'm still convinced that NNSSNNSSNNSS is the way to go for high speed and high power.

Steve
Jul 23, 2007, 09:01 AM
Registered User
morphs's Avatar
Quote:
Originally Posted by stegla
Just a thought?

Is it possible that , at high rpm, timing and switching from the ESC is made less critical by having NNSSNNSSNNSS instead of N S N S N S?

I'm still convinced that NNSSNNSSNNSS is the way to go for high speed and high power.

Steve

Have you ever tried 6 pole, 12 magnets with a delta wind?? I have and they were not good. The amp draw was through the roof and the motor got very hot.
Jul 23, 2007, 03:02 PM
Registered User
stegla's Avatar
Quote:
Originally Posted by morphs
Have you ever tried 6 pole, 12 magnets with a delta wind?? I have and they were not good. The amp draw was through the roof and the motor got very hot.
Morphs
I have only had bad experiences with delta winds.

Today I've just finished a 20mm double with 8T of 22G 'Y' and NNSSNNSSNNSS curved magnets............sweet motor.......destined to go in a small wing.

Steve


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