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Old Oct 24, 2012, 07:45 PM
Aka: Tom Jenkins
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New Bee 12n10p and 12n 8p D, Y, DD, YY rewind education topic

After reading what I can find on a LRK wind, I understand the wind on every other tooth is doubled, I would like to do a star termination for the torque factor, I also understand that the LRK uses either a 10 magnet bell or a 14 magnet bell. One being a 5:1 commutation ratio and the other being a7:1 commutation ratio.
Where is there a winding calculator that a wood worker/ carpenter guy can understand?
Would like to use 6s-8s and a bunch of amps Suggested wind counts from experience is needed.
Thank you for your feed back guys

How much past 200 mph do I need to go you ask?
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Old Oct 25, 2012, 08:38 AM
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Well, I also used the LRK style in 2001 or so when I didn't know better, but nowadays it is simply outdated.
Wind every tooth, it is simpler, has less weight, and the motor has a better efficiency.
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Old Oct 25, 2012, 09:08 AM
Jack
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When you say doubled, do you mean the turn count? If so, and you are changing a dLRK wound motor to a LRK wind, that is not the case. As an example, the first image is a screen shot from a turn calculator spreadsheet. On that you can enter the turn count and termination found on a dLRK wind and it will give the turn counts for LRK and Half Parallel dLRK re-winds.

As you can see there, the 750 kV from the 18 turn dLRK-D wind changed to 825 on a LRK-Y with the same number of turns. And LRK-D would have nearly doubled the kV.

That spreadsheet, and couple of others, can be downloaded here:

http://www.rcgroups.com/forums/showp...&postcount=266

And you can run them with the free openoffice.org calc spreadsheet.

For turn calculators the German powercroco and powerditto pages normally have two nice pages (they include some English translations on them) that are easy to understand. One shows the practical winding schemes in a table format and the other displays an image of a winding scheme and gives some additional info about the scheme.

Those two pages have been down for a while for some changes or something but are worth bookmarking and taking a look at when they are back:

Winding scheme table - http://www.powerditto.de/Kombinationstabelle.html

Winding scheme calculator - http://www.powerditto.de/bewicklungsrechner.html

There is another slightly different version of the winding scheme table here also:

http://forumrc.alexba.eu/nutpol_e.htm

The ditto table, were it still visible now, lists A-b-C-a-B-c- as the LRK scheme for 12N14P motors.

The attached image is the ditto winding scheme calculator's image for the 12N14P A-b-C-a-B-c- LRK Wye wind. That was generated by using the Advanced mode and entering the A-b-C-a-B-c- scheme, the pole count, and choosing the Y termination.

Jack
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Old Oct 25, 2012, 11:46 AM
Aka: Tom Jenkins
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Oh My! Am thoroughly confused now! What and why, on a LRK there are A-B-C x 2,
A-b-C-a-B-c, does the winding change the magnetic commutation? I'm stuck on 10 and 14 magnet bells
As far as the motor is concerned, I'm not worried about efficiency, the only purpose of this motor is for maximum torque and watts from a 6s pack. Again the RPM range needs to turn a heavy pitched prop around 20 to 25k. An 8x13 or 10x13 two or three blade folder. If I had a 1000kv motor on a 6s pack that would be around 22,000 rpm no load, take off 20% and it needs a bit more RPM. From what I can see on the spredsheet thing the 4035 needs 3 turns to make around 1100Kv. Does this allow for better saturation in dLRK or the LRK with doubled turns provide better torque. Where are the F3S guys when you need them? Not sure I've asked the correct questions.
Thanks
Tom
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Old Oct 25, 2012, 03:39 PM
Jack
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Julez wrote:

"..Well, I also used the LRK style in 2001 or so when I didn't know better, but nowadays it is simply outdated..."

I don't agree that it is outdated but we don't want to argue that here...

ApexAero wrote:

"..Oh My! Am thoroughly confused now! What and why, on a LRK there are A-B-C x 2,.."

Maybe you're new to this? I don't argue with what Julez says, there may be better winds for those looking for speed. I think on 12 arm stators the ABC wind with 10 magnets is considered to be the best wind for speed. But you mentioned LRK so that is what I replied about.

That spread sheet I posted is for one specific motor, the numbers predicting the kV's for the other winds will change when the turn count, kV, and termination from another dLRK wound motor is entered in the yellow cells at the top. It might not change much from what you seen there but the numbers are for a specific make and model motor.

If you know the turn count, kV, and termination of 4035 motor you mention I can run that spreadsheet and get the predictions for your motor. And I can get the predictions for an ABC wind for it too on a later version of that spreadsheet.

If understand your question, you don't understand some of the commonly used terms in motor winding. The A, B, and C as used in the figure you posted are the commonly used names or references for the three phases in these motors.

The string of upper and lower case ABC letters is a winding scheme. The case denotes the winding directions in a winding scheme and the hyphens are unwound arms Not to insult you, but if you are not familiar with the upper/lower case alphabetic schemes, I'll refer you to the five part Electric Motors articles here to get started on it all:

http://www.southernsoaringclub.org.za/articles.html

The statement A-b-C-a-B-c- indicates how a LRK wind is wound on a 12 arm stator. The letter A, B, and C still refer to the three phases, the upper case letters are clockwise (CW) turns, and the lower case letters are counter-clockwise (CCW) turns, and the hyphens "-" are the six arms that are not wound.

It is a simple way to describe exactly how the wire is to be wound on the arms for a wind to work. And to further the confusion on this, there are several different images that will produce a working LRK wind.

I had to struggle with winding schemes as I learned this and will explain to read the scheme and image I posted and compare it to yours.

Looking at my image, the arm at 12 o'clock is arm #1 and arms are numbered around clockwise. So the six arms wound are numbers 1, 3, 5, 7, 9, and 11.

The upper case (CW) or lower case (CCW) case letters are determined by looking from the hammerhead towards the center of the stator and using the direction of current flow to decide CW or CCW.

So from Start of phase A on arm #1, it is seen as clockwise or "A" looking from the hammerhead towards the center of the stator. The first half of the phase is on arm #1 and then it transits to arm #7 for the second half.

As phase A continues on arm #7, again viewing from the hammer head end of the arm, the current is flowing towards you and CCW around arm is wound as indicated by the "a".

And the "A" and "a" letters become the first and seventh elements in the scheme "A-b-C-a-B-c-"

Phase B starts on arm #3 with CCW turns for a "b" and finishes up on arm #9 with CW turns for a "B".

Phase starts on arm #5 with CW turns for a "C" and finishes up on arm #11 with CCW turns for a "c".

It still makes my head hurts sometimes...

If I apply the same logic to your scheme for numbering the arms and indicating the turn directions on the image you posted the winding scheme would be:

1 = a or CCW
3 = B or CW
5 = c or CCW
7 = A or CW
9 = b or CCW
11 = C or CW

And for a LRK winding scheme that written as a-B-c-A-b-C-

What is the diffierence in your image and mine? Mine has the starts grouped together on one side of the stator and the ends on the other side of the stator. And the A phase started on arm #! and progressed around the stator in arm #1, #3, and then #5 sequence.

You image has alternating starts and ends, the arms are not numbered, the terminations are not shown, and the arms (if they had been numbered the same as mine) were wound in a #1, #9, and #5 sequence.

The other differences are that mine has the Wye bundle coming from the #7, #9, and #11 arms and yours has it coming from the #3, #7, and #11 arms.

So these differences are all different ways to skin a cat, in the end the three winds are identical in use as far as how the motor runs.

This a a thread with links to just about anything anyone would want to know about rewinding:

(Re)winding and building motors - http://www.rcgroups.com/forums/showthread.php?t=240993

But if you are after a serious speed motor, I think you want to use the ABC wind and 10 magnets.

Jack
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Old Oct 25, 2012, 06:42 PM
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You have to run at least 8S lipo. You have no other choice. Your stator is high voltage, more volts per rpm.

That size of motor is being used on 600mm to 700mm class heli. That's 27" x2 inches variable pitch rotary wing diameter, on a 600 class heli, geared from 8:1 to 11:1. At motor rpm above of 30000rpm, somtimes over 40000rpm. So, shouldn't be a problem with your size of props.
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Old Oct 26, 2012, 05:01 AM
Aka: Tom Jenkins
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Palm Beach County, Fl.
Joined Aug 2008
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Thank you Jack, and boom,
I'm understanding the lower/upper case wind direction, what I'm not grasping is why the two pictures have 6 lugs wound, I can see how one has a N' and S' straight through the stator and why/how it repels the magnet, the yellow pic has all clockwise turns straight through the stator so the opposite lug is wound the same not CCW, theres the confusion to me. Having the possible access to two different magnet bells a 10 and a 14 seems to offer more options after the wind. And yes Jack, if you have the time, a calculation would be helpful in selecting supplies etc. Looks like double wire turns may do the trick after reading more of what I can find presently.
Just so all will know, this is a speed project, it seems these days going fast is all that floats my boat. Thanks to JJMorris for the ESC mods link for the ability to build an ESC to major amps, thanks to Glue Products and Polymer Products here in West Palm for the polymer education and available resins, carbon and glass. As soon as a motor is built and working, a slight redesign of the airframe is in order to fit the equipment. I really look forward to the collaboration and camaraderie and especially burning holes in the sky!
Thanks
Tom
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Old Oct 26, 2012, 07:54 AM
Jack
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As a guy that has only been doing this for a couple of years, the differences in the images, the different arrangements of the starts, ends, and terminations, and the number of different images that can be found for any particular wind really brought a lot of confusion and uncertainty to the learning curve for me. I eventually started just ignoring the differences. I found a wind image that worked and that I liked, and ignore the others.

One of the reasons I came to prefer using the powerditto images is that they also give you the cogging steps info and the winding factor info. And they will give you an error if you try to use an unbalanced or invalid scheme.

As far as looking at an image and seeing all the arms wound in the same direction as in your image (looking from hammerhead to center), that does simplify the winding for some. But the motor will not work that way unless you also have the starts, ends, and terminations as shown there too.

As far as the magnets and the attracting and repelling process, when the PWM voltage is applied to a phase it is seen with various N and S polarities on all six wound arms so there is a combination of pushing and pulling effects taking place between magnets and arms but all are contributing to the direction of rotation. At least that is the way I think of it (I am not very good at the theory of motors).

And both of our images create the same effects even though mine has the arms wound differently than yours. The reason they both work is because of the differences in the arrangement of the starts, ends, and Wye bundle.

To bait an argument from Julez, one reason I like the LRK wind is that it will allow you to get more copper (as either larger wire or more turns) on the wound arms because it eliminates the crowding in the "V" that occurs when you wind all the arms.

In this post in another thread:

http://www.rcgroups.com/forums/showp...16&postcount=6

Christain Lucas (whose name is the "L" in dLRK) said this:

"..rpm per volt and torque per ampere.

Best 12 slot and 14 P with LRK winding ,always and yet and in the future.

Only if you have a very short stator use dLRK winding.

ABC winding only with 8P and 16P on 12N stator,

LRK and dLRK only with 10P and 14P for best result.

To get high rpm/volt use 8P or 10P

And for high torque use 14P or 16P with the correct winding..."


So when I read that I tried the LRK wind and liked it. It is not the only wind I have done and will ever do but it is a wind that is worth tying and that will work well with the right stator. As you can tell from what Mr. Lucas says, it is not the best wind for every stator and pole count combination.

One of the joys of rewinding is to try different winds just to see the result.

I did a LRK wind on a 35mm stator with two strands of wire in parallel (that is what you mean by double wire, right?) and am very happy with the result:

Dualsky XM PR-40 LRK Rewind - http://www.rcgroups.com/forums/showthread.php?t=1457682

That is a motor that is on a glider, it was used with a larger, slower turning, folding prop and for shorter (30 seconds or so) full throttle runs at less than the highest possible input power. The battery in the glider was 3S and not large enough for sustained full power runs that takes the motor to it max ratings. Nor did I want a power system that could do that.

On your 4035 motor, can you tell me the details on the original wind (it must have been a dLRK wind)? I need:

number of turns

the kV (either as you measured it of as per the specs)

the termination (it would be either Delta or Star(Wye))

With that info I can do the spreadsheet for you.

Jack
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Old Oct 28, 2012, 06:50 AM
Aka: Tom Jenkins
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Jack, As far as original wind, I will have access to parts shortly, a friend from years past, during my pylon hay-day, is sending a box of stuff. So, the actual motor is going to be reclaimed parts(kit) and the bells are 10 and 14 magnets. I suppose it is just as good as a kit save for the magnets/bell already glued and factory balanced. We'll have to wait to see what is in the box of goodies to see what the configurations are. Again, I'm not looking for rotational speed, but maximum torque, the airspeed will come from pitch and torque. Weight and electrical efficiency are a factor but not so important for 2-3 min speed flights.
As soon as I know what parts are availible so will you!

Here's a RCG link to the origional start of the rewinding fom 2003 I believe

http://www.rcgroups.com/forums/showt...hreadid=127606
http://www.rcgroups.com/forums/showt...hreadid=174595
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Old Oct 28, 2012, 09:47 AM
Jack
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OK, I browsed that thread a little. Those are classic threads for the CD-ROM motor builders. That all happened before I got into RC and I skipped that part of the the hobby as far as winding any of those motors. I have been strictly rewinding the cheaper motors you can buy.

As far as the turn counts and wire size and stuff, I think you'll find all the details of what worked in the past in those threads. They do not mention the resulting kV's but you can estimate them. And unless you are starting with the same stators and magnets, your results will be similar but not be the same.

But it is easy to see the results they got with various props and then you can just wind and test to close in on your needs/wants/desires.

I think from the way you talk you want to go with the Wye terminated winds, either ABC or LRK (as determined by the magnet counts) to get the better torque characteristics. I think you're going to be winding and rewind to close in on it anyway...

You can see the RPM the props are working best at, if you can get any RPM data for your specific prop, that and the battery voltage will lead you do the kV.

If you need 30,000 RPM loaded on 3S that would be 75% or so of your no load RPM. So that that means you want about 33% more than 30K as a no load RPM. 1.33 x 30K = 40K and that is what you're looking for then.

Jack
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Old Oct 28, 2012, 10:38 AM
Aka: Tom Jenkins
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This is the only 4035 series I could find with a 14p bell. the references were to show how much I've been searching for info and how commited I am to the venture! Should you run a spread sheet here the info on the motor
Stator Diameter 40.0 mm (1.575 in)
Stator Thickness 35.0 mm (1.024 in)
No. of Stator Arms 12
Magnet Poles 14
Motor Wind 15 Turn Delta
Motor Wire 19-Strand 0.25mm
Motor Kv 250 RPM / Volt
No-Load Current (Io) @ 10 v 0.69 Amps
Motor Resistance (Rm) 0.037 Ohms
Max Continuous Current 65 Amps
Max Continuous Power 2700 Watts
Weight 465 Grams (16.40 oz)
Outside Diameter 48.9 mm (1.925 in)
Shaft Diameter 7.98 mm (0.30 in)
Body Length 63.3 mm (2.44 in)
Overall Shaft Length 94.5 mm (3.65 in

I found this on the scorpion site by Dr. Ralph but don't understand it but for the 21V. I still think the wind needs to be in the 20 to 24k rpm range, 19 to 22k loaded to the max. http://www.scorpionsystem.com/buildi...ld_and_review/
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Old Oct 28, 2012, 11:14 AM
Jack
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Here is the screenshot of the result from the Turn Calculator 6 spreadsheet for your motor, I used the 15 turn count, Delta for the termination, and a kV of 250 RPM / Volt in the info you posted.

When I have an accurate turn count and kV the results for the other predictions in the spreadsheet have been very accurate for me. The least accurate kV's are usually the ones I get from the specs as the motor are often not very lose to what they say they should be.

But once you have done a rewind and measured the kV (I do a simple RPM divided by voltage "raw" kV) then used that to load the spreadsheet, I've found that the kV predicitons become more accurate and reliable. Usually within a few percent or less.

I enjoy looking at the croco and ditto pages, sometimes the translations help more than others. All the numbers and the labels in German there just leave me kind of confused. I really don't know what it all means as I am not that technically inclined or even interested in more than the basics.

Jack
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Old Oct 28, 2012, 06:32 PM
Aka: Tom Jenkins
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So using the motor data for a 12n14p at 250Kv delta wind, how do I extrapolate a a wind number for a different Kv. How about spreadsheet grid 11 G, is that a two wire parallel wind of 4 turns each lug for the Kv of 1083 ? I mean did I read it correctly?
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Old Oct 28, 2012, 08:43 PM
Jack
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Quote:
Originally Posted by ApexAero View Post
So using the motor data for a 12n14p at 250Kv delta wind, how do I extrapolate a a wind number for a different Kv. How about spreadsheet grid 11 G, is that a two wire parallel wind of 4 turns each lug for the Kv of 1083 ? I mean did I read it correctly?
11G is the cell for the 4 turn Half Parallel dLRK wind with a Star (Wye) termination. It does not matter if you do the wind with one or two or even 15 strands of wire. If it is 4 turns it is 4 turns.

I think maybe you are confusing the use of the term parallel as it is used for multiple or parallel strands with the term as it is used for the wind named "Half Parallel dLRK". The first is a method of using multiple smaller strands in winding and the second is the name of a type of wind (like dLRK, LRK, ABC, etc.).

And I just realized that the spreadsheet page I posted is not going to help you yet. I entered 15 turns there because I thought that was right but now I know it is probably not right.

When that says "Motor Wind 15 Turn Delta" it probably means there is 15 wires in each slot, not 15 turns around each arm. There are two ways to express the turn count and I may have used the "wires in a slot" count for when I should have used the "turns arround an arm" count.

The difference is that when you have 15 wires in a slot you have 7.5 turns on each arm. 20 wires in a slot would be 10 turns on each arm, etc. So you need to know what method to use and then enter the correct turns around an arm count in the spreadsheet.

Also, it does not say what wind was used, only that it is a "Delta" termination. That spreadsheet will only work if the turns from a dLRK wind are entered in the yellow blocks.

if you look at the yellow boxes at the top I entered 15 turns and a 250 kV for your motor as a dLRK wind. That is what might not have been correct.

The other cells (under columns B, C, D, F, G, H, and I) and in rows 8 and down, contain the Kv's that will result from the turn count and Kv that is entered in the yellow boxes.

So if you can find out if the 15 turns mentioned in the Scorpion specs is a wires in the slot count (I suspect that it is) it would mean that I should have entered 7.5 for the turn around an arm count.

And if you can find out if it was a dLRK wind the spreadsheet will work. But I suspect that the motor is a 12N8P motor and not a 12N14P motor and I don't think you can do a dLRK wind on a 8 pole motor, only on 10 or 14 pole motors.

So I may have rained more confusion than help on this...

Jack
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Old Oct 28, 2012, 09:13 PM
Aka: Tom Jenkins
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Boy I was way off base in understanding your request on info. I thought by having certain peramiters of one motor configuration it could be used to create a version of peramiters that I need.
So if I just had a bare, clean motor that was 12n 14p its possible to work out winding peramiters for a regular LRK winding every other tooth of the stator that I understand to provide maximum torque at a lower rpm range, using 6s equals 22v and wire heavy enough to use on a space heater and not melt. single strand or multipal strand. so my post #4 is where I'm headed still and don't understand how to use a Kv calculator XLpage to figure winding a tooth with how many turns and how heavy of gauge to use and follow the pictures!
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