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Old Oct 07, 2012, 02:29 PM
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Half Parallel dLRK wound DAT-750's
Whats the difference between dLRK and half parallel dLRK. Is that the same as a Y Y connection? I'm not sure on that concept either. I'm imagining it is something like the single winding single direction Modisc is doing?
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Old Oct 07, 2012, 06:27 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Are you aware of the timocharis thread on that wind, that has an explanation of it:

Winding Half-Parallel dLRK Delta - http://www.rcgroups.com/forums/showthread.php?t=1249657

It is a wind that works very well on this motor. I have done three of my DAT-750's with it. As far as explaining it, I'm at a loss on that.

One point of confusion on it for me was that if you do a 20 turn wind Half Parallel dLRK wind you get the Kv that you would get from a 10 turn dLRK wind. So most of the winds that were used on DAT-750's were around 20 turns and terminated "Y" to get Kv's down around 800 or so

The attached image is the one I use, it was posted by Truglodite. There is another image for it around that manuel_v did that brings the motor leads out better if you are going to do a Delta term version.

Jack
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Old Oct 07, 2012, 07:22 PM
What goes up must come down..
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"A rather extreme example, just for calculation's sake/fun: going from 80% to 90% efficiency would increase power by a factor two."

Wow !, although most probably not possible to acheive, it's interesting to know..

Jack,
these planes aren't small maybe the bigger prop is really what you need..it's hard to beleive a DAT can pull these!
I almost bought a rascal but it's smaller brother build for .049" gaz engine for the DAT.
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Old Oct 07, 2012, 07:32 PM
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I've been confused by the half parallel thing too but just taking a fresh look at it realized that a normal DLRK is 4 winds in series where the half parallel is two series winds parallel to the other 2. Take 2 resisters in series you get 2x the resistance of each but in parallel they're 1/2 the resistance. That's the same as a much larger wire with half the resistance equaling half the turns thus double the Kv. Ish, sorta.

I think.

Richard
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Old Oct 07, 2012, 11:37 PM
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Jack.
I think the best wind for APC e 11x7, 11x8, 12x6 is 16 turns, 21AWG DLRK.
Fore low power and great efficiency best 17 and 18 turns.

This motor have low effy to high Kv. 900 and Up.

Manuel V.
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Old Oct 08, 2012, 06:56 AM
Jack
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Quote:
Originally Posted by manuel v View Post
Jack.
I think the best wind for APC e 11x7, 11x8, 12x6 is 16 turns, 21AWG DLRK.
Fore low power and great efficiency best 17 and 18 turns.

This motor have low effy to high Kv. 900 and Up.

Manuel V.
Thanks for the advice, Manuel. I started out just wanting to see what the wind would do and then testing it with props on hand to compare that info. I don't have a specific plane or need for it yet.

And my ignorance of efficiency is apparent. I have been trying to get smarter about that. I went to the Peak Efficiency page and used some of the numbers I have been getting from testing help with my learning curve. And you're right about the low efficiency if I understand that right. I think it is down around 52% based on my initial messing around with the PeakEff calculator. I've attached an image that I got by entering some of the number I got in testing.

I'm still in kindergarten on that so I'm not sure it is right...

And I'm also confused by the fact that the motor seems to run good and to be potentially useful too. I have to wonder if some of us are not happy with inefficient motors simply because we are ignorant of it?

Jack
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Old Oct 08, 2012, 08:47 AM
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Thanks again Jack, I read in the Scorpion thread that some new motors are Y Y connected. At first I was thinking it was the single tooth technique, in a way it is except it uses two teeth. So I'm thinking the Scorpion Y Y is a half parallel wind with two Y terminations.
In that thread it is also mentioned that one tooth has four turns and the next has five turns, thus calling it a 9T. By that logic what I'm calling a 6T would be a 12T. Why not call it what it is, on a 12N stator w/ 6T per N it could be called a 72T/12N motor, accounting for all the turns and teeth. The Scorp would be a 54T/12N. Although I figure the folks who actually create this stuff have reasons that I can't imagine.
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Old Oct 08, 2012, 10:10 AM
What goes up must come down..
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That is why I had better results with SF props on mine and it most probably in the 50% eff. also..:-(
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Old Oct 08, 2012, 10:21 AM
Jack
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The parallel winds are interesting for sure. And they can be based on any of the winds as I understand it. I have read of it being used on ABC and dLRK winds too. I thought at first that it was only two windings in parallel but now understand that three or move can be used. That is sometimes referred to as YYY, DDD, etc.

Here is a thread that has some interesting discussion on it, it touches on some of the complexities of how parallel winds on different motors changes the kV's and the like:

http://www.rcgroups.com/forums/showthread.php?t=1308217

Jack
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Old Oct 08, 2012, 06:53 PM
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Jack.

This explanation of Mr. LB Miller in post no.35 gives us a very wise behavior in a heat engine.
http://www.rcgroups.com/forums/showt...corpion&page=3

Manuel V.
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Old Oct 08, 2012, 08:52 PM
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Thank you Manuel!! Even I understand it now.

Richard
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Old Oct 09, 2012, 08:36 AM
Jack
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Quote:
Originally Posted by manuel v View Post
Jack.

This explanation of Mr. LB Miller in post no.35 gives us a very wise behavior in a heat engine.
http://www.rcgroups.com/forums/showt...corpion&page=3

Manuel V.
Wow! Thank you for that link!

That is post #35 in a thread that is almost 8,800 posts long and over five years in being. I have read posts in that thread here and there but since I don't have any Scorpion motors I never really had any strong interest in it.

The respect I have for them as a company has just increased a lot. And Lucien's post is simply wonderful. It has so much motor knowledge packed into one post that it is incredible. He is the Man of the Century as far as explaining brushless motors to newbies! And the better understanding of motor terminology is and the basics of electricity is all thrown in for free!

Jack
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Old Oct 11, 2012, 07:32 PM
Jack
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rodair,

Got that HZ PKZ1005 10 x 8 prop and tested it today on the 800 Kv LRK wind motor.

3S

15 seconds @ 3,366 RPM, 11.61V, 3.1A, 36W temp 66F to 67F
17 seconds @ 4,411 RPM, 11.16V, 6.60A, 74W temp 67F to 70F
full throttle
26 seconds @ 5,123 RPM, 10.61V, 10.92A, 117W temp 69F to 74F

4S (on 5S A123 pack)

12 seconds 2,821 RPM, 16.35V, 1.58A, 26W temp 77F to 80F
26 seconds @ 3,937 RPM, 16.11V, 3.57A, 58W temp tem 75F to 76F
14 seconds @ 5,539 RPM, 15.44V, 10.55A, 163W temp 73F to 77F
full throttle
10 seconds @ 5,834 RPM, 15.22V, 13.12A, 200W temp 77F

So this prop looks like another candidate for use on this motor with 3S and 4S packs.

Looks like a nice prop, a little heavier and stiffer plastic than GWS props. The blade is wider than a GWS DD prop and probably has a little less blade area than s similar sized GWS SF prop. The hub is heavier and stronger than a GWS SF prop would have so I'd rate it as stronger than those.

In the testing there was no audible or visible fluttering and it ran very smooth, It needed no balancing right out of the package. It is set up to be tractor mounted, the back of the prop hub has a 7mm hex nut socket and that provided a no play fit on a tapered cone prop saver with Thera-Band prop saver bands. The front face of the prop is flat and there is a 4mm/0.156" through hole. To mount it as a pusher with the flat face facing the motor might require some drilling out or other creativity.

I hit a little over 6,000 RPM with that a couple of times and would consider that to probably be a practical to use but maximum RPM for this prop for now. Over time you might find it will go a higher but I've never been one to want to test props to their breaking point just to see what they will take..

I fumbled around a little on getting this wind terminated. I wanted to transition to stranded wire close to the motor and did it by forming a small "U" bend on the 21 AWG solid wire close to the motor and then laying a piece of fine stranded 18 AWG on the "U" and soldering it. I put double shrink tube over the solder joints.

To immobilize the motor leads against vibration I looped a small (4") cable tie down around one of the unwound stator arms. Then I looped a second tie through the first and captured the three motor leads at the point where they made the transition from solid to stranded. That doubled ties raised the motor leads up and away from the edge of the magnet housing a little and should keep them from every getting into contact with the rotating housing.

Jack
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Old Oct 12, 2012, 06:23 AM
What goes up must come down..
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Jack, I am glad you post these results Thanks.
Not too bad prop worth considering on DAT motors especially when you said 4S
It's good for my motor and type of flying / plane ioo bad they don't have 11" dia.
Nice and neat wires terminaison using tie wrap that's a great idea!
Are you going to try DLRK? or keep this one as is?
I just got it's brother motor here the "AIR L3010C" 1300 Kv rated 420W that I want to test the thing here it's the same motor mount for a lot more heavier bell housing motor with only 2 small grub screw to hold it, same threaded shaft to hold the prop etc..I don't know about the sator I didn't dismantle this one yet.

Roger
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Old Oct 12, 2012, 07:31 PM
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Quote:
Originally Posted by rodair View Post
I just got it's brother motor here the "AIR L3010C" 1300 Kv rated 420W that I want to test the thing here it's the same motor mount for a lot more heavier bell housing motor with only 2 small grub screw to hold it, same threaded shaft to hold the prop etc..I don't know about the sator I didn't dismantle this one yet.Roger
The L3010C I had needed the mount torched before it would come off. I thought it was epoxied but no its a force fit. Maybe just manufacturing tolerances but it really irritated me to go to that extreme since the mount had to be removed to attach to the firewall then the motor reinserted. Going to buy the 'B' version next time.


Richard
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