Wind on LRK - RC Groups
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Mar 23, 2007, 11:29 PM
Electric's are cool

Wind on LRK

On a 38 Dia by 7 deep stator, I have 31 turns of .6mm wire on 1 tooth now , I reckon I could get 40 turns on it

Is 40 turns on an LRK equal to 20 turns on a DLRK

I run a 3S battery that can run at 16 amps constant
and a 9/4 APC / should I leave it at 31 turns or make it 40
Thanks a lot in advance
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Mar 24, 2007, 07:52 AM
Electric's are cool


I see now from another post you adjust the max current the motor pulls by increasing or decreasing the number of turns,,,,,, so I choose my prop, first ,, either a 9/4 or 10/5 and then adjust my turns using an amp meter to get 16 amps at WOT. This sounds easy now.
Mar 24, 2007, 02:19 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Originally Posted by Geoff Woodward
... Is 40 turns on an LRK equal to 20 turns on a DLRK ...
Almost, Kv will be 10% higher, roughly. To get the same Kv you'd have to use 2*22 winds in DLRK.

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; Mar 24, 2007 at 02:25 PM.
Mar 25, 2007, 06:02 PM
Electric's are cool


Delamination across the nation , not good,, but I dont think it will matter the stator is 7 deep and the magnets are 6/6/1
the good thing is the shaft is rock solid the bearings are a 15 micron( 25 microns is 1 thou ) press fit in the bearing housing and the shaft is a slide fit in the bearings < Im pleased with it , 3 coats is nice and thick The paint seems good ,
My first motor the shaft was loose in the bearings 30 microns and the bearings were about 10 microns loose in their holders so when I fly I get a vibration in the airframe when I turn or pitch the model, just a slight buzz
Mar 25, 2007, 08:15 PM
Electric's are cool

I hit the big time

I borrowed a DVM from work that can measure 20 Amps so now I can check my first motor for volts and Amps

Im a bit worried about DVM's though when I checked voltage with my cheapDVM my ESC hit the soft LVC without the meter in place it didnt the meter must be using some juice ???
Mar 26, 2007, 05:12 AM
Electric's are cool

I measured my volts and Amps

I got a strange bad result the amps were not even 11 Amps around 10.5 and the ESC was surging ,I assume its the Soft cut LVC cutting in, this is with 2 batteries than can run at 16 Amps constant, I noticed that when I took the DVM out of the amp test circuit the motor did have more power so the DVM does drag the power down .
Next the volts , with the DVM in circuit for volts I was getting LVC also at around 9,2 volts and surging
I must have a cardboard stator or steel wire for winds, I would throw in the towel except for it doesnt fly too bad
The real long leads on the DVM must be a problem , but the basic motor, or the unknown hand me down ESC might have to go
DVM's are a pain ,they tell you things you dont want to Know
Mar 26, 2007, 06:12 AM
Electric's are cool

I can think of one thing that is bad news

Was holding the DVM probes against the connectors by hand,, I figure that is wasting about 1,5 amps , and long DVM leads are bad ,,I cant get 2.4 gold bullets from Aircraft world , I figure its about 12 amps with 9.5 volts in the air at WOT.If that ,
Mar 26, 2007, 10:34 PM
Electric's are cool

I had an idea

Used my lipo charge leads to do an Amp check ,they have 2.4 gold bullets on and short leads ,,, well 16.5 amps the motor is pulling at WOT, but with the DVM in circuit it still hits the soft cut of the LVC of the ESC ( surging ), with a full battery

( Why is it pulling the voltage down so low at WOT )

Thats pleasing,,,,, 9 volts at 16 amps is 144 watts that is why the model hauls OK

Im looking for some Loctite epoxy that is good for 90 C to glue my magnets in although superglue works I would like to try something else on the 2nd motor
Mar 26, 2007, 10:55 PM
Good Better Best quest.
olmod's Avatar
go for the loctite 480 known as black max.i use it for all .
Mar 27, 2007, 07:25 PM
Electric's are cool


The loctite 480 superglue looks good for magnets ,,, 100C
Had 2 flights this morning , Im thinking that a higher C battery will fix my voltage drop problem on this little power hungry sub 2Oz motor , Im pleased as its only .5mm laminations, but it has got a low carbon flux ring on Im sure the soft iron I used has a lower carbon than mild steel , I dont know what oridinary piping is these days in the carbon range , but I may look it up
With these state of art .2 laminations, that are around the place looks like the best ones are the ones with the lowest carbon mainly and sulphur and oxygen, and other things, to a lesser extent , that is determined by how well the heat treat process was done in each case ,

So its a sort of guessing game as to how good your electrical steel is,,, that is at the core of your motor , they are definatly not all equal

I saw the test result of some steel few weeks back and it was not quite what the manufacturer claimed in his specifications
Mar 27, 2007, 07:54 PM
Good Better Best quest.
olmod's Avatar
I know what you mean about not up to spec's,the flux ring iron is the hardest to scource if you want the best,the only scource i have is made to order and comes only in solid round bar ordered by the ton.
Mar 27, 2007, 08:26 PM
Electric's are cool

By the ton

Gee thats a lot of motors

So seeing that carbon has such a big influence over the way your stator works( how efficient its is) maybe you could add it to your list of important things, in order of their importance , I saw a few weeks back

1 Carbon content of steel in Stator
2 Lamination thickness
3 Winding technique
4 Stator , magnet gap
5 And so on
Mar 27, 2007, 09:44 PM
Electric's are cool

Something else

That Im in the dark about too

Is the tooth thickness , when I cut my first stator I just took a guess , about what looks right , so my teeth might not be a good thickness

And also I was thinking of .;,, seeing that the magnet is flat,, of making the top of the hammerhead flat too

I reckon that outrunner design is too static, and unchanging at the moment and that something else is needed ,maybe a cross between and innrunner and outrunner , thats if I knew how an outrunner works , I dont have the faintest , nobody talks about them
Apr 17, 2007, 05:12 AM
Registered User
I made my first LRK motor, from a HDD stator, 25.6 mm OD, 3.67 mm height, 5x5x1 N50 magnets, 25 turns of 0.5 mm diameter copper wire. I expected a slow rotating, high tourque motor, but I am dissapointed for several reasons:

1. According to my measures, it runs at 20000 rpm (measured with DPR tachometer), which is higher than my previous CD-ROM motors.
2. The current draw is 2 A, which also looks high.
3. The CC Phoenix 10 ESC stopped sometimes, which I have never epxerienced before.

I am not sure that the winding is correct, but I wound only every second tooth, the first clockwise, the second anti-clockwise. I connected the coils into a star configuration, i.e. I connected all the ends together, and I connected all the starts to the ESC.

What could be wrong?


Apr 17, 2007, 05:47 AM
Electric's are cool


Mine is connected Delta , like 99% of LRK motors also the thin depth stators apparently go better with a DLRK wind, dont understand the 20000 RPM and 2 Amps , thats propless I suppose
How does it go on an 8/4 prop ?
That motor in picture has 2 flights and really hauls good

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