Topics

Flywheel magnet orientation.


lowflyer582
 

Hi group. Hoping for some help.
Like Mick. I am just doing a 1000 hour top end on my 2200a s/n 1158.
For a long time I had noticed that my flywheel magnets were looking pretty shabby, so while I have the flywheel off, to do the flywheel mod, decided to purchase some new rare earth magnets as they are called and install them.
I stripped the old ones out, should have taken more care with working out the orientation, but didn’t.
I have laid in the new ones temporarily, in doing this, you have to have the first one, north facing outwards, the middle north facing inwards and the third, outer magnet north facing outwards again. Otherwise in trying to force them in if the middle one is north facing out, the polarity makes them go berserk.
Now the question. If I put a compass up to one side pickup, it attracts North, if I go to the other pickup, it attracts south. Not being a physicist I was thinking both pickups, should read the same and should they be 2 x north facing out and the middle South facing out, or 2 x south facing out and the middle north facing out.
Just didn’t want to bed them in and screw them down before getting some definite on this.
Picture of old ones to see how shabby they were. Also they were moving in their seats.
Thanks.

Roly.


lowflyer582
 

Just a bit more feedback.
Have just rearranged the three magnets, all north facing out. This is a bit of a struggle as they are trying to pop apart, until captured in the seat.
The strength on the pickup is much stronger, can pick the flywheel up with a bolt attached to the pickup.
So guessing they should all be in the same direction.
Still open to offers of any other theory ?

On Wednesday, March 17, 2021, 15:44, lowflyer582 via groups.io <lowflyer582@...> wrote:

Hi group. Hoping for some help.
Like Mick. I am just doing a 1000 hour top end on my 2200a s/n 1158.
For a long time I had noticed that my flywheel magnets were looking pretty shabby, so while I have the flywheel off, to do the flywheel mod, decided to purchase some new rare earth magnets as they are called and install them.
I stripped the old ones out, should have taken more care with working out the orientation, but didn’t.
I have laid in the new ones temporarily, in doing this, you have to have the first one, north facing outwards, the middle north facing inwards and the third, outer magnet north facing outwards again. Otherwise in trying to force them in if the middle one is north facing out, the polarity makes them go berserk.
Now the question.  If I put a compass up to one side pickup, it attracts North, if I go to the other pickup, it attracts south. Not being a physicist I was thinking both pickups, should read the same and should they be 2 x north facing out and the middle South facing out, or 2 x south facing out and the middle north facing out.
Just didn’t want to bed them in and screw them down before getting some definite on this.
Picture of old ones to see how shabby they were. Also they were moving in their seats.
Thanks.

Roly.






glen english LIST
 

Hi Roly

Caution. Higher magnet strength is not necessarily what you want.

Too much and you will overload (too much voltage) the ignition coils and most likely provoke a ignition coil failure during flight when things are hot.

Depending on the design, they might need to be all NNN or alternating NSN etc.

I will try and find some documentation on this today. I am sure someone is near a plane might tell you by direct measurement.

On 18/03/2021 4:26 am, lowflyer582 via groups.io wrote:
Just a bit more feedback.
Have just rearranged the three magnets, all north facing out. This is a bit of a struggle as they are trying to pop apart, until captured in the seat.
The strength on the pickup is much stronger, can pick the flywheel up with a bolt attached to the pickup.
So guessing they should all be in the same direction.
Still open to offers of any other theory ?
Roly.


Sent from Yahoo Mail for iPad <https://overview.mail.yahoo.com/?.src=iOS>

On Wednesday, March 17, 2021, 15:44, lowflyer582 via groups.io <lowflyer582=yahoo.co.uk@groups.io> wrote:

Hi group. Hoping for some help.
Like Mick. I am just doing a 1000 hour top end on my 2200a s/n 1158.
For a long time I had noticed that my flywheel magnets were
looking pretty shabby, so while I have the flywheel off, to do the
flywheel mod, decided to purchase some new rare earth magnets as
they are called and install them.
I stripped the old ones out, should have taken more care with
working out the orientation, but didn’t.
I have laid in the new ones temporarily, in doing this, you have
to have the first one, north facing outwards, the middle north
facing inwards and the third, outer magnet north facing outwards
again. Otherwise in trying to force them in if the middle one is
north facing out, the polarity makes them go berserk.
Now the question.  If I put a compass up to one side pickup, it
attracts North, if I go to the other pickup, it attracts south.
Not being a physicist I was thinking both pickups, should read the
same and should they be 2 x north facing out and the middle South
facing out, or 2 x south facing out and the middle north facing out.
Just didn’t want to bed them in and screw them down before getting
some definite on this.
Picture of old ones to see how shabby they were. Also they were
moving in their seats.
Thanks.

Roly.






lowflyer582
 

Hi Glen, yes get what you are saying.
The manual, has a very short instruction re replacing magnets.
Just says, when replacing magnets, the (N) pole must be orientated outwards on the flywheel.
So I am reading that as NNN all facing outwards.
Also shows a picture of a spring scale, attached to a prop cap screw, and the pull off, should be 1.5 to 2.5 kg or 3.3 to 5.5 lbs.
Have not got a spring scale handy, but will check. Definitely with NSN configuration the strength would not achieve minimum.
Thanks.

On Wednesday, March 17, 2021, 21:12, glen english LIST <glenlist@...> wrote:

Hi Roly

Caution. Higher magnet strength is not necessarily what you want.

Too much and you will overload (too much voltage) the ignition coils and
most likely provoke a ignition coil failure during flight when things
are hot.

Depending on the design, they might need to be all NNN or alternating
NSN etc.

I will try and find some documentation on this today. I am sure someone
is near a plane might tell you by direct measurement.

On 18/03/2021 4:26 am, lowflyer582 via groups.io wrote:
> Just a bit more feedback.
> Have just rearranged the three magnets, all north facing out. This is
> a bit of a struggle as they are trying to pop apart, until captured in
> the seat.
> The strength on the pickup is much stronger, can pick the flywheel up
> with a bolt attached to the pickup.
> So guessing they should all be in the same direction.
> Still open to offers of any other theory ?
> Roly.
>
>
> Sent from Yahoo Mail for iPad <https://overview.mail.yahoo.com/?.src=iOS>
>
> On Wednesday, March 17, 2021, 15:44, lowflyer582 via groups.io
> <lowflyer582=yahoo.co.uk@groups.io> wrote:
>
>    Hi group. Hoping for some help.
>    Like Mick. I am just doing a 1000 hour top end on my 2200a s/n 1158.
>    For a long time I had noticed that my flywheel magnets were
>    looking pretty shabby, so while I have the flywheel off, to do the
>    flywheel mod, decided to purchase some new rare earth magnets as
>    they are called and install them.
>    I stripped the old ones out, should have taken more care with
>    working out the orientation, but didn’t.
>    I have laid in the new ones temporarily, in doing this, you have
>    to have the first one, north facing outwards, the middle north
>    facing inwards and the third, outer magnet north facing outwards
>    again. Otherwise in trying to force them in if the middle one is
>    north facing out, the polarity makes them go berserk.
>    Now the question.  If I put a compass up to one side pickup, it
>    attracts North, if I go to the other pickup, it attracts south.
>    Not being a physicist I was thinking both pickups, should read the
>    same and should they be 2 x north facing out and the middle South
>    facing out, or 2 x south facing out and the middle north facing out.
>    Just didn’t want to bed them in and screw them down before getting
>    some definite on this.
>    Picture of old ones to see how shabby they were. Also they were
>    moving in their seats.
>    Thanks.
>
>    Roly.
>
>
>
>
>
>






glen english LIST
 

the magnets would need to be spaced for NSN to work, or be very slow.
The NNN configuruation I guess sets their pulse duration. It's optimal for one RPM, so a compromise for all others, nevertheless, it is effective.

Too much magnetic flux = too high voltage, potentially arc over in the coils , carbonizing and failure (of both perhaps !)

there is probably some basic test that it should be able to fire over some gap X but not some larger gap Y. I think the test is only that is should be able to fireover some spark gap X, nothing else - IE just have sufficient voltage and energy to fire over a specified gap.

Dont drop them, or rap them or subject them to any sort of shock- magnetic behaviour may change.

On 3/18/2021 9:38 AM, lowflyer582 via groups.io wrote:
Hi Glen, yes get what you are saying.
The manual, has a very short instruction re replacing magnets.
Just says, when replacing magnets, the (N) pole must be orientated outwards on the flywheel.
So I am reading that as NNN all facing outwards.
Also shows a picture of a spring scale, attached to a prop cap screw, and the pull off, should be 1.5 to 2.5 kg or 3.3 to 5.5 lbs.
Have not got a spring scale handy, but will check. Definitely with NSN configuration the strength would not achieve minimum.
Thanks.
Roly.
Sent from Yahoo Mail for iPad <https://overview.mail.yahoo.com/?.src=iOS>
On Wednesday, March 17, 2021, 21:12, glen english LIST <glenlist@cortexrf.com.au> wrote:
Hi Roly
Caution. Higher magnet strength is not necessarily what you want.
Too much and you will overload (too much voltage) the ignition coils
and
most likely provoke a ignition coil failure during flight when things
are hot.
Depending on the design, they might need to be all NNN or alternating
NSN etc.
I will try and find some documentation on this today. I am sure someone
is near a plane might tell you by direct measurement.
On 18/03/2021 4:26 am, lowflyer582 via groups.io wrote:
> Just a bit more feedback.
> Have just rearranged the three magnets, all north facing out.
This is
> a bit of a struggle as they are trying to pop apart, until
captured in
> the seat.
> The strength on the pickup is much stronger, can pick the
flywheel up
> with a bolt attached to the pickup.
> So guessing they should all be in the same direction.
> Still open to offers of any other theory ?
> Roly.
>
>
> Sent from Yahoo Mail for iPad
<https://overview.mail.yahoo.com/?.src=iOS
<https://overview.mail.yahoo.com/?.src=iOS>>
>
> On Wednesday, March 17, 2021, 15:44, lowflyer582 via groups.io
> <lowflyer582=yahoo.co.uk@groups.io
<mailto:yahoo.co.uk@groups.io>> wrote:
>
>    Hi group. Hoping for some help.
>    Like Mick. I am just doing a 1000 hour top end on my 2200a s/n
1158.
>    For a long time I had noticed that my flywheel magnets were
>    looking pretty shabby, so while I have the flywheel off, to do the
>    flywheel mod, decided to purchase some new rare earth magnets as
>    they are called and install them.
>    I stripped the old ones out, should have taken more care with
>    working out the orientation, but didn’t.
>    I have laid in the new ones temporarily, in doing this, you have
>    to have the first one, north facing outwards, the middle north
>    facing inwards and the third, outer magnet north facing outwards
>    again. Otherwise in trying to force them in if the middle one is
>    north facing out, the polarity makes them go berserk.
>    Now the question.  If I put a compass up to one side pickup, it
>    attracts North, if I go to the other pickup, it attracts south.
>    Not being a physicist I was thinking both pickups, should read the
>    same and should they be 2 x north facing out and the middle South
>    facing out, or 2 x south facing out and the middle north
facing out.
>    Just didn’t want to bed them in and screw them down before getting
>    some definite on this.
>    Picture of old ones to see how shabby they were. Also they were
>    moving in their seats.
>    Thanks.
>
>    Roly.
>
>
>
>
>
>


jabcamit@...
 

They must be NNN to work.  The magnets in combination with their surrounding iron laminations, and the iron laminations in the magneto need to form a magnetic loop. Think of a horseshoe magnet attracting a bar of steel (where the magneto laminations is that bar.  The outer two poles on the flywheel magnet are South and the centre pole is North. As thse poles slide past the magneto laminations the magnetic field in the magneto suddenly reverses  (ends go from N>S to S>N) and its that rapid reversal that generates to volts to make the spark.

I doubt if the energy generated by the magnetic field will  have very much heating effect on the coils, but even if it did better to have  a nice juicy spark than risk misgfiring if a plug gets oiled, dirty  or whatever.
 

BobP


glen english LIST
 

Hi Bob

that's a good explanation.

On the heat- its not about getting the windings too hot , it is about too much voltage/energy firing over (arcing) the windings and damaging the insulation (permanently) . No more spark. Potentially a double failure.

Hot windings are more likely to be damaaged, depending on the insulation type used. I've always been of the opinion that the ignition coils used in the jab should be relocated  somewhere cooler...

On 20/03/2021 10:21 pm, jabcamit@panth.co.uk wrote:
They must be NNN to work.  The magnets in combination with their surrounding iron laminations, and the iron laminations in the magneto need to form a magnetic loop. Think of a horseshoe magnet attracting a bar of steel (where the magneto laminations is that bar.  The outer two poles on the flywheel magnet are South and the centre pole is North. As thse poles slide past the magneto laminations the magnetic field in the magneto suddenly reverses (ends go from N>S to S>N) and its that rapid reversal that generates to volts to make the spark.

I doubt if the energy generated by the magnetic field will  have very much heating effect on the coils, but even if it did better to have  a nice juicy spark than risk misgfiring if a plug gets oiled, dirty  or whatever.


BobP


Mick O'Connor
 

Why the discussion, there is only one way for those magnets to fit in the flywheel !

Mick

On 20 Mar 2021, at 19:44, glen english LIST <glenlist@cortexrf.com.au> wrote:

Hi Bob

that's a good explanation.

On the heat- its not about getting the windings too hot , it is about too much voltage/energy firing over (arcing) the windings and damaging the insulation (permanently) . No more spark. Potentially a double failure.

Hot windings are more likely to be damaaged, depending on the insulation type used. I've always been of the opinion that the ignition coils used in the jab should be relocated somewhere cooler...

On 20/03/2021 10:21 pm, jabcamit@panth.co.uk wrote:
They must be NNN to work. The magnets in combination with their surrounding iron laminations, and the iron laminations in the magneto need to form a magnetic loop. Think of a horseshoe magnet attracting a bar of steel (where the magneto laminations is that bar. The outer two poles on the flywheel magnet are South and the centre pole is North. As thse poles slide past the magneto laminations the magnetic field in the magneto suddenly reverses (ends go from N>S to S>N) and its that rapid reversal that generates to volts to make the spark.

I doubt if the energy generated by the magnetic field will have very much heating effect on the coils, but even if it did better to have a nice juicy spark than risk misgfiring if a plug gets oiled, dirty or whatever.


BobP




lowflyer582
 

Thanks Bob. That is the way I have positioned them. NNN facing outwards. As I said before, a bit of a struggle to place them, as they try to fight each other, but have resined them in now and clamped them.
With the bolt pull off test, achieving about 2.5 KG. Pretty strong.
Engine slowly coming back together.
Flywheel mod now done.
Cheers.

On Saturday, March 20, 2021, 11:21, jabcamit@... wrote:

They must be NNN to work.  The magnets in combination with their surrounding iron laminations, and the iron laminations in the magneto need to form a magnetic loop. Think of a horseshoe magnet attracting a bar of steel (where the magneto laminations is that bar.  The outer two poles on the flywheel magnet are South and the centre pole is North. As thse poles slide past the magneto laminations the magnetic field in the magneto suddenly reverses  (ends go from N>S to S>N) and its that rapid reversal that generates to volts to make the spark.

I doubt if the energy generated by the magnetic field will  have very much heating effect on the coils, but even if it did better to have  a nice juicy spark than risk misgfiring if a plug gets oiled, dirty  or whatever.
 

BobP


glen english LIST
 

Roly are you sure you are using the correct cross screw driver ?
they look at bit attacked.

They are a head called : Phillips ACR

Not standard Phillips.

I have them and they fit well on my Jab screws. far better than many "phillips style I have.

I have also found that a #2 posidriv fits them better than standard Phillips, depending on the wear of on the screw heads.

Mind you, there are about 10 different minor versions of 'Phillips"

-glem


lowflyer582
 

Well spotted, sadly tried three different cross head screwdrivers, but none were brilliant as you can see. I did put some stud lock on the screws and have since put some witness paint on them.

On Saturday, March 20, 2021, 23:26, glen english LIST <glenlist@...> wrote:

Roly are you sure you are using the correct cross screw driver ?
they look at bit attacked.

They are a head called : Phillips ACR

Not standard Phillips.

I have them and they fit well on my Jab screws. far better than many
"phillips style I have.

I have also found that a #2 posidriv fits them better than standard
Phillips, depending on the wear of on the screw heads.

Mind you, there are about 10 different minor versions of 'Phillips"

-glem







glen english LIST
 

mmm

for badly hacked ACR heads, try posidrive #2.

On 3/21/2021 9:00 PM, lowflyer582 via groups.io wrote:
Well spotted, sadly tried three different cross head screwdrivers, but none were brilliant as you can see. I did put some stud lock on the screws and have since put some witness paint on them.
Roly.
Sent from Yahoo Mail for iPad <https://overview.mail.yahoo.com/?.src=iOS>
On Saturday, March 20, 2021, 23:26, glen english LIST <glenlist@cortexrf.com.au> wrote:
Roly are you sure you are using the correct cross screw driver ?
they look at bit attacked.
They are a head called : Phillips ACR
Not standard Phillips.
I have them and they fit well on my Jab screws. far better than many
"phillips style I have.
I have also found that a #2 posidriv fits them better than standard
Phillips, depending on the wear of on the screw heads.
Mind you, there are about 10 different minor versions of 'Phillips"
-glem