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Old Aug 19, 2012, 12:30 PM
Jack
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delete me...
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Old Aug 19, 2012, 01:07 PM
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South Africa, GP, Pretoria
Joined Jul 2003
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Quote:
Originally Posted by xener View Post
nope, i never wondered why numbers of turns are alwayz even, because they are actually not.
for example scorpion`s motors - S3014-1040 13turns, S3014-1220 11turns, S3026-890 7 turns.. btw, what is slot ? two adjacent teeth in your example? one wire(phase) goes around 4 teeth on 12 pole motor, isn`t it ?
im sorry about my beginner`s questions, but i can`t find any info about this numbering.
so, in 14T motor, it means 14 turns per tooth, or per slot (two teeth) or per all 4 teeth in one phase ?
Sorry, I was referring to the older version Scorpion motors, not version-II. Look at this page. All the motors are even-numbered. Obviously, Scorpion are now doing LRK-winds, where only every alternate tooth is wound and therefore the full turn-count can be put on one tooth. Can someone please confirm this.

LRK winds are not very common these days and I have never seen any Turnigy motors being wound this way. Most outrunners are wound dLRK or "distributed LRK" where every tooth is wound with half of the turns of the turn-count.

Yes, slot means the valley between teeth.

Christo
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Old Aug 19, 2012, 01:57 PM
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United States, GA, Alpharetta
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thank you both for answers to my doubts. original G15 is dlrk, delta , now im thinking about star with one wire if it would be possible, Im going to check some conversion tables to check what i can do. Some kV up is not a problem, its a motor for WWII plane.
S3014-1040 V2 is running in my Katana S30, and every tooth is wound, its not LRK. But seems like not every manufacturer count turns the same.
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Old Aug 19, 2012, 02:39 PM
Jack
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Old Aug 19, 2012, 03:35 PM
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my apologies , this is my new thread: http://www.rcgroups.com/forums/showthread.php?t=1715068

jack, please move your valuable posts there, please.
and of course, i would like to ask thread owner to delete my posts, please.
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Old Aug 19, 2012, 03:49 PM
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South Africa, GP, Pretoria
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Quote:
Originally Posted by xener View Post
S3014-1040 V2 is running in my Katana S30, and every tooth is wound, its not LRK. But seems like not every manufacturer count turns the same.
Interesting. I know for a fact that Scorpion counts winds per slot and not per tooth, because I've wound some Scorpion kits to factory spec and confirmed this myself.

If they do 13 winds on the S3014-1040 V2 motor, then they must have found a way to do half turns per tooth. I've thought about it before, but never tried it myself. "Half turns" will give you more Kv possibilities. It's a great idea if it can be done.

Christo
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Old Aug 23, 2012, 05:56 AM
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hello again, i have one more question, if i can`t fit two 20AWG wires , can i use combination of one 20AWG+one 21AWG ?
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Old Aug 23, 2012, 06:08 AM
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Originally Posted by xener View Post
hello again, i have one more question, if i can`t fit two 20AWG wires , can i use combination of one 20AWG+one 21AWG ?
Yes, I've mixed wire gauges many times. However, there are people who will tell you that you shouldn't do it. It works for me.
Christo
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Old Aug 23, 2012, 09:20 AM
Jack
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Like Skylar says, that will work fine.

As long as the two strands are soldered together at the ends you have sum of the resistance of the two wires in parallel. We don't really care what the value of that is, it is just that the more copper there is in the phase the lower the resistance will be and the higher the current can go.

We were joking around about it once and I designed a closer to perfect wind, it would be made with large and small wires with each succeeding smaller wire being sized to fill the gap left by the previous wires. Each strand would have three wires in my design, you can see a cross section of it in the image. No one does actually does that of course, can you imagine trying to keep all that in place as you worked?

And, did you know, there is such a thing as square motor winding wire so as to leave less unused space?

Jack
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Old Aug 23, 2012, 10:23 AM
low tech high tech
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Hexagonal might work. Closer to round, easier corners.
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Old Oct 31, 2012, 10:57 AM
homo ludens modellisticus
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near Nijmegen, Netherlands
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Permanent Magnet Motor Simulator
Emetor: a PMSM design tool

Uit
groups.yahoo.com/group/lrk-torquemax/message/13495
Quote:
... Here you can start doing some basic design end start to get the right skill to understand how motor works. Of course is a generic software so is not 100% correct , once you get very close to the physical limit the granularity of FEM (Finite Element Model) create some artifacts and deviance form the real world so get ready to have at least a 5% difference between the model and the real motor. ...
About the Finite Element Method
en.wikipedia.org/wiki/Finite_element_method

Vriendelijke groeten Ron
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Old Nov 01, 2012, 01:52 PM
Duh
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grain valley mo, or about 25 minutes east of kansas city
Joined Jan 2004
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Quote:
Originally Posted by Skylar View Post
Crashawk
I can't agree with your statements above. It IS amps that causes a motor to heat up and burn the windings.
Look carefully at this formula: R x IČ = copper loss.
R (or Rm) is the resistance in one phase of an outrunner motor. So, amps squared times the Rm is what causes the primary loss in a motor, i.e. the main source of heat.
In outrunners, iron loss is usually much smaller than copper loss and can also be calculated: Io x volts, where Io is the no-load current.

Christo
most people around here can't use formulas, it's easier to remember what the max watts recomended by the manufacturer is, and most have a max wattage, not max amps since if they rated it at x amps for say, 2 cells someone would try to run it at the same amps on 4 cells and very quickly burn it up. it's all in the watts. lol.

either way you look at it though, I still recomend a meter if you are going to experiment. a good way to measure the temp of the stator is a good idea too if you are really going to push it.

Jason
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Old Nov 04, 2012, 04:49 PM
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Thrust vectoring motor mount(suprisingly simple stuff) (1 min 15 sec)
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Old Nov 05, 2012, 12:14 AM
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South Africa, GP, Pretoria
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Quote:
Originally Posted by crashawk View Post
most people around here can't use formulas, it's easier to remember what the max watts recomended by the manufacturer is, and most have a max wattage, not max amps since if they rated it at x amps for say, 2 cells someone would try to run it at the same amps on 4 cells and very quickly burn it up. it's all in the watts. lol.

either way you look at it though, I still recomend a meter if you are going to experiment. a good way to measure the temp of the stator is a good idea too if you are really going to push it.

Jason
Hi Jason

I'm sure it works for you if you are guided by Watts. That is a safe method and there's nothing wrong with that. But... there are some of us who like to push our motors and how do we know what the limit for a motor is? We go by the amps, since amps determines the heat generated in a motor - not Watts! As stated before, the other determining factor is Rm (motor resistance). Finding (or winding) a motor with low Rm is of utmost importance. That is what drives the guys on this forum: http://www.helifreak.com/forumdisplay.php?f=291

These days I often run my motors at double the specified "max Wattage" by using more cells, but staying within the amps limit. Obviously, it often means using a different motor with lower Kv, depending on the cell-count and prop size I want to use.

When I started learning about electric motors, I was also stuck in the "Watts-way of thinking". But fortunately some motor manufacturers stated max amps (not max Watts). That got me thinking and then I finally started understanding how a motor really works. So give it time -You'll come around (hopefully).

Have fun
Christo
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Old Nov 05, 2012, 11:34 PM
Duh
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grain valley mo, or about 25 minutes east of kansas city
Joined Jan 2004
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[When I started learning about electric motors, I was also stuck in the "Watts-way of thinking". But fortunately some motor manufacturers stated max amps (not max Watts). That got me thinking and then I finally started understanding how a motor really works. So give it time -You'll come around (hopefully).

Have fun
Christo[/QUOTE]


I learned a lot from a couple of local manufacturers, working for one winding motors and the other (castle creations) answered a lot of questions from me as several of their employees fly locally, some even in our indoor club for a long time. (and I allways bugged them for all the info I could) I used to build motors just to test what I learned. built a cdrom motor that did 350 watts on 4 cells turning a 3 inch prop 36000 rpm, scared the bejesus out of me and my brother and sounded like a freight train. (was told that was impossible) also built an outrunner from the blower motor from a semi-truck. 5 inches across the bell and our largest prop (24x12) was nowhere near big enough to tax it. at 3500 watts it ran colder than the ambient air temp producing over 25 pounds of thrust. still have it but can't afford to do anything with it for now. had to start over from scratch on everything due to a fire and still havent started building motors again, just wasn't enough insurance to replace all the parts, pieces and tools I had before the fire. been flying since 1988 and doing electric planes since 1990, started flying brushless motors and lipo batts around 10 or 12 years ago and pretty much went electric on everything about then. before the fire had around 65 or 70 planes all with motors I built in them from 4 ounce micro planes to 6 pound warbirds. lost over a hundred planes in the fire and 60 kits and half a chord of balsa wood. I don't throw anything out here unless I got it from a reliable source and checked it out myself. my chances of "coming around" are nill, lol, too set in my ways after all these years.
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