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Old Oct 29, 2009, 01:15 PM
C.H.E.A.P.
lance dalton's Avatar
Chino Hills, CA.
Joined Nov 2004
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Tested my 12T 24AWG #2 and it performed a little better than the first 12T at less amps. I got 10,900 rpm / 11.09 volts / 9.88 amps / Rhino 610 3s / GWS 8x4 DD. I also tried my friends 1000mah 3s and it was about 25 oz. thrust at about 12 amps. This things gona RIP (_!_)

Lance

ps Thanks Julez that explains it well.
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Old Nov 13, 2009, 02:00 AM
C.H.E.A.P.
lance dalton's Avatar
Chino Hills, CA.
Joined Nov 2004
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First dLRK..no shorts :)

Wound my first B&R Wonder 13T 24AWG dLRK....YAHOO!!! It was tight from the first set of teeth but I gotrdone. It's packed! I'll try it out this weekend and compare it to my 12T 24AWG ABC.....as long as it ramps .

Excellent dLRK winding tutorial thread you started Dave. It was a great help.

here's a couple pics.

Lance
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Old Nov 13, 2009, 09:43 AM
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Nice looking wind, Lance!

Like you, I wound the 12 turn 24awg and had been planning on the 13 for my next wind and first DLRK. I've got the stator ready, but had been procrastinating. I think your effort may inspire me to step up to the plate.

(Probably I'll be reporting back soon on some thick wire & short teeth; get your calipers ready )
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Old Nov 13, 2009, 10:37 AM
Dave North
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USA, CA, San Jose
Joined Apr 2004
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Hey Lance, you clearly have the touch. Nice work! Now for some zoom zoom ...


Dave
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Old Nov 14, 2009, 08:43 AM
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Fourdan's Avatar
Antony (France)
Joined Sep 2003
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Blue&Red W

Hi
I am new to this thread about B&R Wonder
I see some 14 mag or 16 mag rewound references
It's not clear to me
Are there two variants of rotor config at buying ?
Or do you modify to pass from 16 down to 14 ?
What are the coverages (%) obtained for 14P or 16P variants ?
Louis
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Old Nov 14, 2009, 09:07 AM
Dave North
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Quote:
Originally Posted by Fourdan View Post
Are there two variants of rotor config at buying ?...
What are the coverages (%) obtained for 14P or 16P variants ?
Louis, yes, there are two variants. Like the original Blue Wonder, the 3000 Kv model is dLRK with 14 magnets. The others all have 16 mags. Coverage on the 16-mag variants is 100%. They both use the same magnets, so coverage on the 14 mag version is ~88%.


Dave
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Old Nov 14, 2009, 09:28 AM
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Antony (France)
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Quote:
Originally Posted by timocharis View Post
Louis, yes, there are two variants. Like the original Blue Wonder, the 3000 Kv model is dLRK with 14 magnets. The others all have 16 mags. Coverage on the 16-mag variants is 100%. They both use the same magnets, so coverage on the 14 mag version is ~88%.


Dave
Hi
Dave I catch it
Could you graph two curves for the 14 and 16 mag variants :
No load losses (volt * amps product) versus rpm (WOT)
using a variable V power supply, and the same ESC to vary rpm
If possible on two or several rewound B&R close Kv, or different Kv
Thanks
Louis
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Old Nov 14, 2009, 04:17 PM
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New York
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I'd like to run a rewound R&BW on 3 cells and a 7" dia prop in one of these (MDC F-14) http://www.rcgroups.com/forums/showthread.php?t=769451. Many folks are putting big motors on these, i think building light with a strong single makes more sense.

Any recommendations on a combination of 7" dia prop and wind (turns and wire gauge) that will get me to about 130 to 150 watts?

Is 130 to 150 watts (input) unrealistic for this motor?

Thanks,
George
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Old Nov 14, 2009, 04:51 PM
Dave North
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USA, CA, San Jose
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Quote:
Originally Posted by MGeo View Post
Is 130 to 150 watts unrealistic for this motor?
Not really. It will probably be further than ideal past the efficiency point, but the motor will take the load no problem (assuming a good wind). It's going to end up 10 or 11 turns Wye or 17-18-19 turns delta. The Wye would be with 24awg probably; 10 turns of 23 is doable but your amp load might go too high.

Delta winds would be 26 awg, though you can manage 17 turns of 25 (with the same problem as the 10T 23g Wye). The easiest would probably be the 11-turn 24awg Wye. Might be a little on the conservative end, but you're talking about Watts input, I'm sure, and the Watts Out will be better than you probably expect.

This is assuming a 7x6 APC E. You'll also probably be able to get away with the 7x6 SF with an 11T. The 7060 GWS RS will overspin at that power level, so we can pretty much forget about it. Not sure what other viable props might be.

Dave
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Old Nov 15, 2009, 04:32 AM
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Dave,

Thanks for the expert response. I was talking about watts in.

I'll line up the right parts for the 11-turn 24awg Wye wind. I'll get a couple of 7x5 and 7x6 APC Es to try with it on 3 cell LiPo.

Are these recommendations with a 14 magnet bell wound dLRK? (my assumption), or 16T wound ABC?

Finally, do you have a ballpark Kv you would expect the 11T Wye would generate?

Thanks again for the help.
George
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Old Nov 15, 2009, 10:58 AM
Dave North
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Quote:
Originally Posted by MGeo View Post
Are these recommendations with a 14 magnet bell wound dLRK? (my assumption), or 16T wound ABC?
Those were for 16-mag ABC, which is what most people ask about due to fear and loathing of dLRK. And they are just guesses -- I don't have much use for overamping or high rpm or APC props, so my data is limited.

With a 14-mag dLRK setup you can either add a turn or stand pat and get even more RPM. On a plane like that, it's unclear why fine throttle response would matter much, and noise issues don't usually come up. The ABC setup will probably be slightly (and I do mean slightly) more efficient. This is of course not taking into account manufacturing variances in the motor blanks, which can easily lead to dLRK equivalents that outperform ABCs -- but that's not how the averages work out.

An 11-turn ABC Wye would give you about 1500 Kv (probably a little less, but no guarantee). For a 12-turn dLRK the Kv goes up to more like 1550 if my numbers mean anything. Variability from motor to motor can be surprising.


Dave
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Old Nov 15, 2009, 11:58 AM
Dave North
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As an exercise in "where this will all fall" we can take a look at a somewhat ideal setup. Assuming a motor of 1500 Kv, we want to run roughly in the 70% range to be anywhere near the efficiency peak. This would be 1050 RPM/Volt.

Assuming the battery gets pounded down below nominal, let's figure it ends up running in the range of 10.5 volts. That gives us a resultant RPM of 11025 "at the prop."

If we're running a 7x6 APC E at that RPM, Drive Calc tells us that's roughly 120 watts out. If we assume a best-case ~ 80% efficiency (possible, but...) we get about 150 watts in, which just barely makes the grade.

Since batteries never hold right, numbers never work right, and motors always produce less than we should, this makes 1500 a reasonable target RPM to fall into your range. But as you can see the variance is a bit unknown, and things could go either way.

Obviously, going for a higher Kv risks losing efficiency. Going for a lower Kv risks hitting a power level that's inadequate -- not really likely with that plane. And in the real world, getting a big enough battery to hold 10.5 volts on that setup would imply a weight allowance that begs instead for a larger motor.

Well hey, thanks for clearing that up, huh?


Dave
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Old Nov 15, 2009, 05:59 PM
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Hey Dave, I stripped a perfectly good 2730 tonight and I think I'm gonna try to duplicate your 21t 26awg ABC delta wind. I'm curious, do you remember what length of wire you used for this wind? Thanks
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Old Nov 15, 2009, 06:54 PM
Dave North
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Quote:
Originally Posted by Flatulator View Post
...do you remember what length of wire you used for this wind?
I used 62 inches per phase. I'd go 65, just in case you feel the need to do a few end trims for lacing convenience. Heck, wire is cheap -- especially 26 awg.


Dave
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Old Nov 15, 2009, 07:09 PM
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Thanks Dave. I will post photos when I am finished. That is, if I can do it
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