ive tried to wind numerous motors with the LRK terminated wye and none will go and ive read others here having similar problems which i think go beyond just the winding. i understand how the winding guide works and A-b-C-a-B-c....or could be done A-B-C-a-b-c if the wye bundle is chosen differently. ive wound many motors doing dlrk with wye no problem. i know i can get a lot more copper on with the LRK though and I can’t figure what could be the problem.

Is it possible maybe a function on the esc like boost or advanced angle would be needed?

I'll post some good pics of my winding and some vid of my attempt to run it as it stutters and uses high current.

i always do it wye to reduce the kv and will try some delta today.

Originally Posted by Hummina

ive tried to wind numerous motors with the LRK terminated wye and none will go and ive read others here having similar problems which i think go beyond just the winding. --<snip>--

If you are using the winding guides that have been posted on the previous pages the motor will run with any ESC and the standard connections to it. Here is another thread that gives an example of putting a an LRK wind on a 12 arm stator:

LRK Wind on DAT-750 - It's a good one! - https://www.rcgroups.com/forums/show...postcount=1409

You do have to have the turns on the right arms and in the right direction and the connections between the motor and the ESC have to be right but that is a pretty simple thing to do...

Check your work carefully, you must have something other than right. And good luck with it!

Jack

Figured it. Thanks for all your help.

Originally Posted by Hummina

Figured it. Thanks for all your help.

Good for you! Did you notice the comparison testing results in that thread I posted a link to? This wind can be a significant improvement when you are running a motor at a more or less constant throttle setting and don't want or need bursts of power occasionally. If would be my first choice for flights where I wanted to extend the flight duration.

I did a temporary termination for testing and added 3.5mm bullets. I got lucky again and it ran smooth and quiet. When I ran the rewound motor with the test prop I got the following:

GP 10 X 4.5 SF = 5,744 RPM, 11.58V, 10.00A, 116W
full throttle temp rise 74F to 92F in 38 seconds
estimated thrust = 688 grams

And for comparison, the numbers for the stock DAT-750 motor are:

GP 10 x 4.5 SF = 5,338 RPM, 11.02V, 19.12A, 211W
full throttle temp rise 75F to 81F in 15 seconds
estimated thrust = 600 grams

So the LRK wind give me an 8% increase in full throttle RPM, a 48% reduction in current draw, and a 15% increase in thrust.

Jack

Originally Posted by jackerbes

Good for you! Did you notice the comparison testing results in that thread I posted a link to? This wind can be a significant improvement when you are running a motor at a more or less constant throttle setting and don't want or need bursts of power occasionally. If would be my first choice for flights where I wanted to extend the flight duration.



Jack

no i didnt read it all and theyre long and generally I'm hunting for specific things. i wonder why it would do better at a constant throttle. I wish i had done some tests on the motors i just rewound to compare the km and see how much better a motor it even is.

but for sure i always can fit more copper with the lrk than dlrk so for me it's like a 10% better motor in that way and then its simpler, so easier to make, and quicker, and less likely to screw it up. id rather use it than any other winding. and i think it safer in having the phases separated and less likely to have an across phase short, and also the motor then has less wires in contact with higher voltages between them and less likely to break down. .in theory.



i have my cool little inductance meter..be interesting to see how much inductance is added from each coil. are the top most or the inner most coils the more effective. or if 16 coils with lrk vs 8 coils on each with dlrk. is it exactly the same? probably not. but my hands are tired today.

Originally Posted by landru

It is a question of geometry: you need more wire to wrap a given tooth with X turns compared to wrapping two of the same teeth with X/2 turns.

Put simply: as you apply more layers of wire, the effective circumference of the tooth grows. In dLRK that circumference grows less. The wire in the slots is the same however.

The 'wire savings' in DLRK result in lower resistance for the same turns per phase.

This has me wondering if its worth going with a DLRK wind over LRK.

Erased post.

Hi Hummina,
sometimes less is moore. The new Lehner outrunner serie , https://www.lehner-shop.com/aussenlaeufer/torqstar-41/ .
All parts designed for less loss. So good result for high efficancy at high load.
All messururing with motor and controler , the first real LRK motordesign.

Happy Amps Christian

It wouldn’t take too long to figure but does the inductance built by turns around a tooth, that shows on my L/C, equate to increased kt? I assume it does. Or could just wind lrk and dlrk and compare but I don’t want to waste the time n wire. Maybe the wider coils further from the teeth produce less inductance and in that way dlrk would be better. Regardless I’ve always been able to get on a lot more copper doing lrk and it’s easier and less time consuming and likely more valuable than the benefits of the winding being closer to the tooth.


In this last pic there’s a lot of endturn material and the coils are large. I assume they compared to other windings and chose it based on performance benefits regardless

Are there any settings on the esc that are worth adjusting with an LRK or low kv winding? I find it will cog until faster than 13% duty cycle.

Originally Posted by Christian Lucas

Hi Hummina,
sometimes less is moore. The new Lehner outrunner serie , https://www.lehner-shop.com/aussenlaeufer/torqstar-41/ .
All parts designed for less loss. So good result for high efficancy at high load.
All messururing with motor and controler , the first real LRK motordesign.

Happy Amps Christian

Hi Christian
The Lehner 4125/4140 are not common
I see 6 coils but the slots seem to have different pitches
Have you more pictures to see the stator slots
Lehner data are not very detailed for a given number of turns
Have you data for one real Torqstar 4125 (air cooling)
** turns ? Delta or Star ?
** no load zero current Kv ( rpm/V)
** Io at recommended voltage
** Phase-phase resistance (ohm) @ 20°C or any known temperature
Louis

Hi Hummina and Louis,
the coils are pre fabrikated outside and pressed under very high load to get a copperfilling of over 75% . Normal round wire will allways lower than 50% no way to get moore.
Louis, i have all this pics and Data but will wait after September to show them. The Motor in the pic is a 5 turn delta, 4125 best efficancy at 15 Volt 500 Amps 93,3 % the phase to phase resistance is 1 milliohm. IO at 15 Volt i have to messure . But this is not the limiting volt. The motor can do official 35000 rpm . At your owen riske 40000 rpm are possible.
Do you know the original,paper to the sps winding ?
https://www.aerodesign.de/peter/2001...0_Wroclaw.html .
This was the paper i start the lrk motor . At Magnet Motor GmbH we build much bigger motors .The Lehner has a new magnetsystem that is not the same as in the paper. Modern calculation of flux and loss help to get the best.

Happy Amps Christian

Originally Posted by Christian Lucas

Hi Hummina and Louis,
the coils are pre fabrikated outside and pressed under very high load to get a copperfilling of over 75% . Normal round wire will allways lower than 50% no way to get moore.
Louis, i have all this pics and Data but will wait after September to show them. The Motor in the pic is a 5 turn delta, 4125 best efficancy at 15 Volt 500 Amps 93,3 % the phase to phase resistance is 1 milliohm. IO at 15 Volt i have to messure . But this is not the limiting volt. The motor can do official 35000 rpm . At your owen riske 40000 rpm are possible.
Do you know the original,paper to the sps winding ?
https://www.aerodesign.de/peter/2001...0_Wroclaw.html .
This was the paper i start the lrk motor . At Magnet Motor GmbH we build much bigger motors .The Lehner has a new magnetsystem that is not the same as in the paper. Modern calculation of flux and loss help to get the best.
Happy Amps Christian

Hi Christian
Thanks for all your infos
I summarize
LMT 4125 : 480 g
windings 5 turns per coil
6 coils on 12 slots with specific pitches (2 coils serial for each phase)
I suppose "6 sectors SPS" diagram (AcBaCb)
14 magnets
Rph-ph = 1 milliohm !!! seems very low
Io @ 15 V to be measured (with rpmo) : then zero current Kv (rpm/V) to be computed
Peakeff 93.3%
Very interesting to compare in the future with Scorpion SII4025-xxx or HK4025-xxx
I would be happy to test one motor like that LMT.
Louis

are the teeth different widths on the motor above? it looks like the winding is sitting off from the tooth with air between at the end turns, surely that cant be ideal but i guess part of the squishing process.
the big pcb for terminations is super cool. i wonder is it fiberglass and how thick the copper traces.



this motor here isnt shorted through windings or to the stator but for sure dont trust it beyond spinning on my desk and have to get kevlar insulation
And the tooth is missing epoxy but ok lrk

Originally Posted by Christian Lucas

Hi Hummina,
sometimes less is moore. The new Lehner outrunner serie , https://www.lehner-shop.com/aussenlaeufer/torqstar-41/ .
All parts designed for less loss. So good result for high efficancy at high load.
All messururing with motor and controler , the first real LRK motordesign.
Happy Amps Christian

Hi Christian
Regarding your 4125 picture with 6 sectors, 6 coils
If the stator diameter is 41mm, the circumference (360deg) = 128.8mm
So each sector/6 = 128.8/6 = 21.467mm
My deduction is
one slot = sector / 7 = 3.067 mm (rectangular , no hammer head) ?
one small tooth = sector x2 /7 = 6.133 mm (internal a coil)
one big tooth = sector x3/7 = 9.200mm

Am I right ? Could you confirm
I plan to simulate (FEM) the difference of BEMF (or Kv) between a SPS organization and a classical LRK with 14 magnets
Louis

Hi Louis,
you can calculate what you want . As the magnetsystem is different it playes a big rule . Also how the coils are conected.
As i know that there are many copyshops are waiting i will not tell moore. Spezial someone from Scorpion motors told allways that all the technic i show will not worke is mad know how , he has test this befor and was worth to think about. This motor show that he is wrong in all directions . We know how to calculate motors and some other things.

Happy Amps Christian