Building 65mm stator motors

Several links to projects:
http://www.rcgroups.com/forums/showthread.php?t=1091039

Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group
• Drive Calculator download & discussion group • int. electric fly-in, Nijmegen, the Netherlands

Thanks for the links!

I've got a general question to ask as a part of my research.....

If you were to take two of the 65mm diameter x 65mm long stators....and
make a really long stator, 130mm... How would the motor parameters
change? Would you double the torque constant? Would the velocity constant
drop in half? Seems like wiring resistance would double for a given gauge wire.

I'm gonna try to look it up, but any takers?

I'm thinking about starting with two HXT 80-100s and combining the shells, stators, windings, and
putting it on a common shaft.

The 65mm 18 slot stators that gobrushless offers would be highly configurable, i.e. stackable.

12p3phPMDC said:

I've got a general question to ask as a part of my research.....

If you were to take two of the 65mm diameter x 65mm long stators....and
make a really long stator, 130mm... How would the motor parameters
change? Would you double the torque constant? Would the velocity constant
drop in half? Seems like wiring resistance would double for a given gauge wire.

Click to expand...

Yes.

Resistance would be a bit less than double (you're not doubling the length of the wire in the end-turns).

Torque per Ampère would double, rpm per Volt would halve.
Power would double, roughly spoken.

Vriendelijke groeten Ron

Gentlemen, Thanks for the feedback.

I think that a double HXT in could be made 6" end to end.
That would make it easy to integrate with 6" rectangular tubing.
If I was to make two motor plates and sandwich the double,
I could run a second set of reduction pulleys on the right side.

What do you guys think about a thin sleeve that is a light press fit
over the two bell housings to tie them toghether?
A little of that special green loctite and you've got a new 2x long bell.

You would have to make sure the magnets are in phase.
And then you'd have to tie the stators together somehow as well.
After the end bearings are taken out and the stator unwound, you can Epoxy
the two together face to face and put a coupling inserted in the center.
Then you would need a hardened shaft double length.

Anyway...back to cutting..

http://www.pjs.cz/

http://www.modelmotors.cz/index.php?page=61&product=5330D&serie=20&line=GOLD

Double stator, coaxial, contra-rotating:
http://home.hetnet.nl/~ronvans/outrunner/contrarotating_tandem_lrk.doc

Vriendelijke groeten Ron

Wow, what a nice set of motors on that contra-rotating prop setup.
It reminds me of the volvo-penta drive with cr-props.


Ron,

I pulled your summary/translations out and will post them here...

Thanks for posting here....You are bringing alot
to the motor knowledge pool!!

Andreas built a very nice setup here, I'm impressed!!

It would be a perfect fit for a planetary CVT setup.
You could drive the ring gear with the bell of the forward most motor (akin to the rear prop)
and the sun gear with the rear motor (akin to the forward prop).
Then take the output off the planet carrier.

View attachment double_contra_rotating.JPG

For posterity I attached the complete English&German View attachment contrarotating_tandem_lrk.doc (Word, not pdf)

Several beautiful coaxial contrarotating designs, pics&vids
http://www.rcgroups.com/forums/showthread.php?t=246407&highlight=contrarotating
Coaxial contrarotating, very outrunnerish, by user 'ilbronzo'/'newilbronzo'
http://www.rcgroups.com/forums/showthread.php?p=4538589#post4538589

12p3phPMDC said:

... It would be a perfect fit for a planetary CVT setup. ...

Click to expand...

How does that give a CVT (assuming that cvt is continuous variable transmission)

Prettig weekend Ron

In a very interesting way... 8)

I'll bump an old thread...

hello all 1st post here.
I notice the inline dual is wound LRK.(picture posted by 12p3phPMDC)
Question for Ron: (i recognize you from the rc forums I lurk at occasionaly) or anyone who knows.

1) Is there any side by side comparison on the standard wound Vs LRK in larger outrunners?
2) Are LRK winds > < or=2 standard winds regarding synch issues under load with censorless
controllers?

I have yet to stumble upon a english debate with enough data to inspire an attempt at a larger build.
I have built a couple small bldc motor kits (park flyers) & am intreaged by the Bicycle aplications since stumbling onto this site. looks like LRK would allow easy hall sensor placment. I am a mechanic more than an an electrician. I know that things get more challanging as the scale increases, please refer me to any info you may be aware of. thanks & good luck

12P,

The issue I see with making a true double length, single widing motor as you are suggesting is end bell overhang. It would be crazy long. You would need an end bell support bearing IMHO.

I love these motor projects, though. Quite often new parameters become apparent that the simple math does not account for.

Matt

Recumpence,

Yea, I agree that the bell length grows dramatically and that you would
want to support the end with a bearing, i.e. a motor sandwich, one plate for the
mount, the other plate for the end bearing.

The back to back counter rotating versions could be a bit easier in that sense.
The nice thing is that when you mount the firewall side of each motor
to the center mounting plate...the bearings are well supported
and you don't have this big cantilevered bearing load like you mentioned...

And instead of bearings on the end of the front motor bell in the counter rotating
example, you can just secure the shaft to the end of the bell with set screws and
flat spots or pin it. This would tie to the two motors together...

Another variation would be to couple the end bells together with cooling holes...
If you had a motor sandwich with two end plates, the firewall side of each motor
could be mounted to each end plate. Then the shaft would be supported without
addiotional bearings.... Cooling would be the biggest challenge.

But you would still need an outer support bearing when it comes time to take
power out of the assembly.....so...no free rides eh?

But the stators would be independent, and you would need two controllers...
no biggie...but more complex...

The biggest reason to do a double stator is just to knock the Kv down, well and the other good
reason...more power!

I just picked up a small mill/lathe benchtop combination machine with two motors, one for the mill and
the other for the lathe.... an old Shop Task unit.

I've been building a heavy duty bench for it out of some assorted 4x4 timbers, tongue and groove frame, and a maple top....I can't wait!!!

So, now, I just have to pick something and do it...!
eCVT?
Back to Back?
End to End?
Single Stator?
Choices, choices...