Discussion Lrk or Lrk?

[SexyJet]

Hi

I red about if you want a very high torq. motor, then you should go for
Lrk rewind??
(in the Pdf file that one can download!!)
that means that every other theath is winded? right?

But here in a german site i am reading the oposit. They build very high
rpm motors with the same rewind?

which one is right then?

http://translate.googleusercontent.c...3m-E2MifFtxQ9Q


Thank's

[Christian Lucas]

Hi ,
every thing is right.If you ad highest torque with high rpm you will get highest power to weight density .Nothing other the Boy are doing with the high speed aircraft motor.
Here is the Beast with original LRK winding , http://translate.google.com/translat...ate.google.com .
It´s allso a very torquee motor ,better than all you will find in the modelbuilder univers.

[rich smith]

Originally Posted by SexyJet

(in the Pdf file that one can download!!)
that means that every other theath is winded? right?

If every other theath is winded then you DEFINITLEY want to use Lrk instead of Lrk.

(Sorry Sexy, even I can't resist making fun sometimes. )

[SexyJet]

Christian and Rich

I thank you very much for your response, but i think that i have
express myself very badly, because i haven't got any answers yet?

Here i go again:

I downloaded a pdf file(I think it was a scorpion motor with high torq.)
As we all know high torq. motors aren't so good in rpm?
But then i find this german site, that this guy has actially brokken acouple
of records with his motor which is rewinded just like the pdf file that i downloaded a while ago!!!???

So my question is how that can be?
I have learned that there are different methode one can rewind to get
high torq. or high rpm. And i have never come or red to a point which
a high torq. motor can break the speed record(something around 450 km)

Oh, Gush i hope that i could explain myself better this time?

By the way rich, no harm done. As long as you are happy

[SexyJet]

Originally Posted by Christian Lucas

Hi ,
every thing is right.If you ad highest torque with high rpm you will get highest power to weight density .Nothing other the Boy are doing with the high speed aircraft motor.
Here is the Beast with original LRK winding , http://translate.google.com/translat...ate.google.com .
It´s allso a very torquee motor ,better than all you will find in the modelbuilder univers.

Hi Christian

You mean that i never have any need to rewind any motor then LRK?
Of LRK is so good both for very high torq. and very high speed motors
Then why have we(or all these factory's ) have made all these DLRK
motors??
I have rewinded a few motors until now, and i read and i try and i learn.
But i have to admit this is very new for me lrk motor?
I have rewinded a brushless Lrk motor for my 3D plane, but i dont know
anymore. I certainly have to learn much more about lrk motors

Thank's Bro

Regards

[rich smith]

Originally Posted by SexyJet

By the way rich, no harm done. As long as you are happy

Thanks for being a good sport.

I've wound many Star and a few Delta but only 2 LRK because I find it hard to concentrate on complicated turn patterns. So not an expert on LRK unlike Christian who invented this configuration.

I have concluded diameter is most important when it comes to torque. I like to use big props for aerodynamic efficiency so torque is more important than speed or maximum power. My best motors torque wise are Star CD-ROM type with thin stator and wide diameter.

Also strong magnets, small gap (low Kv) and high tooth count help. You sacrifice speed for torque so it's kind of like gear ratios. If you put enough power (few turns of heavy wire) then you can get speed AND torque but at a cost.

[Christian Lucas]

as Rich wrote ,how to size a motor is a option of dia to lengh.For higher torque a big dia with a shorter stator will be the goal and for this the dlrk winding pattern is better as the endwinding is closer ,shorter on a short lengh stator.
The high speed motors are moore the longer typ and with it a every second tooth coil with less turn like 4 -6 turn will have close ,short endwinding give very good results ,but best for it will be a spezial design for the plates.
In realy big motors for trains ,bus , tanks the endwinding dosn´t realy exist .

Wy are so many factorys use the dlrk winding ? Most are copy shops , don´t think to much about ,thats all.

[timocharis]

sj:

I've wound bunches of motors ABC, dLRK and LRK. There is no one winding style that suits all stator sizes and shapes, regardless of whether the target is torque or speed specifically. Which is just another way of saying what Christian and Rich already said.

Depending on the stator character, magnets, air gap etc, sometimes the one that works best turns out to be a surprise. And on other motors stators, it really doesn't matter much at all -- you get roughly the same result LRK <-> ABC.

So don't worry about the winding scheme. It's better to think about what will work best for the hardware at hand. And maybe get a surprise!


Dave

[Beaverdam]

Originally Posted by SexyJet

Christian and Rich

I thank you very much for your response, but i think that i have
express myself very badly, because i haven't got any answers yet?

Here i go again:

I downloaded a pdf file(I think it was a scorpion motor with high torq.)
As we all know high torq. motors aren't so good in rpm?
But then i find this german site, that this guy has actially brokken acouple
of records with his motor which is rewinded just like the pdf file that i downloaded a while ago!!!???

So my question is how that can be?
I have learned that there are different methode one can rewind to get
high torq. or high rpm. And i have never come or red to a point which
a high torq. motor can break the speed record(something around 450 km)

Oh, Gush i hope that i could explain myself better this time?

By the way rich, no harm done. As long as you are happy

A motor of any type can be wound for (comparatively) high torque or high RPM, depending on the number of turns on each tooth. Some types may be more suited for one or the other. Magnet pole count has a similar effect.

A motor is also a generator, and under no load will accelerate until it produces as much voltage internally as it is recieving*. As it accelerates to this speed the current it draws will drop off. Adding a propeller or other load keeps the motor from reaching it's no-load speed, and it draws current such that the power (amps X volts) going in is equal to the power being produced*.

*(not considering inefficiency factors - bearing and air drag, wire resistance, etc.)

So if a motor is wound with 20 turns per tooth it will produce a certain RPM per volt (Kv) at no-load and a certain amount of torque per amp (Kt) under load. If you rewind the same motor with 10 turns per tooth using wire of twice the cross section area it will produce twice the Kv and half the Kt, approximately. It will need a smaller prop or the amperage will be much higher and possibly produce more heat than it can handle.

Reconfiguring magnet poles has a similar effect, voltage is generated by changing the magnetic field in the coils. So halving the pole count will roughly double the Kv and halve the Kt. There is an important relationship between magnet width and tooth width, so this is not as certain. Magnet strength and airgap also play into it.

Hope this helps.

[SexyJet]

Thank's Guys

for helping me clear that up. Because as i wrote before i was shore after
reading the pdf file that this kind of windings are for bigger props and higher torq.
and i have to say that i am already amazed that someone has break a speed record with the same winding.
Offcourse now i understand better after you have described that there are many other things that play in motors output

.......I have to.............. do this, and i will...............Hmm


Have a great day everyone..........

[Christian Lucas]

We all want the eg laying cow ,turning the big prop for a silent glider and next switch the motor in the speedplane breaking the local club record.It´s not that easy.

[timocharis]

Originally Posted by Christian Lucas

We all want the egg laying cow...

Right! But in the end we have to settle for milk, even if it's really good. The link you forwarded from Ralph is a perfect example. Here's a guy who very much knows what he's doing, but notice he changes the design every time.

That's the way it is, sexyjet. Just when you think you have it right, a better idea pops out. Maybe. But you don't really know until you build the motor.


Dave

[manuel v]

Originally Posted by Christian Lucas

We all want the eg laying cow ,turning the big prop for a silent glider and next switch the motor in the speedplane breaking the local club record.It´s not that easy.

Maybe with QDS conector
http://www.rcgroups.com/forums/showthread.php?t=630990


Manuel V.

[lance dalton]

That's a great idea Manuel. High kv or low kv with a plug. I like it!

Lance