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Old Apr 27, 2005, 12:33 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
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GBx Double..Wye or Delta..or what?

Hi all,
I wound a GBx Double with cheese. 17 turns of 26ga. newb wire. Wound ABCABCABC Wye w/ 12 magnet poles. My testing equipment is pretty limited (have a tach, but not used on this yet), but with a 10 x 3.8 apc, it would barely hover, and I would assume it's due to the lack of rpm, because of how I wound it. I have read for a double use 1/2 the number of turns to get the same kV as a single, but did I listen? Of course not! I wanted a long run time!

I would like to swing a 10" or smaller prop. I do have a 1320mA 3cell pack, but would like to fly with 2 cells 1050mA. Airplane is 3D balsa profile at about 10 oz. or less.

My questions are:
1) Should I just start putting props with more pitch on till I get the thrust?
2)Should I try going to delta?
3)Should I try 6 mag poles?
4)or what?

Thank you, but please do not point me to the GBx performance database, as the amount of info on doubles is pretty slim at best.

Thanks in advance,
Rich
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Old Apr 27, 2005, 12:42 PM
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mjdee14's Avatar
Nashville TN, USA
Joined Jun 2004
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I thought the dtat base was pretty good in the fact that every double I saw that had any power (thrust) was terminated in a delta...

I wound one with 21 turns of 26 g and tried both Y and delta..the delta seems better but I have not flown it yet on an a/c...

Sorry I can't be of more help....I'm sure some of the motor experts will chime in eventually...
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Old Apr 27, 2005, 01:17 PM
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Pacific Northwest, USA
Joined Oct 2004
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I am no expert but seems like to big of a prop to me. I have about the same motor and do a Direct Drive with an 8040 prop. And even a smaller prop like a 6" gets the RPM up for me.
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Old Apr 27, 2005, 01:59 PM
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Joined Aug 2004
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I guess my first question would be: what would it barely hover, a 10oz 3d plane or a buick LaSabre ? Next I would say that you're under proped for that # of turns, especially if you want to run it on 2 cells. My best GBx with cheese is a 13t 24g 12p mated to a 10x4.7 rs prop on 3 cells 8.5 amps 23oz of thrust. If I were to go to 2 cells I'd use a 11x4.7 prop. If you were to reterm delta you would have essentially a 10 turn wye motor which you'd want to run about a 7-8 inch prop on. My suggestion is to rewind with fewer turns and larger wire.

Latrans
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Old Apr 27, 2005, 07:02 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
480 Posts
I think I could swing a 12 x 6..lol
latrans,
Hey thanks for the info. I did say the weight in my first post "I would like to swing a 10" or smaller prop. I do have a 1320mA 3cell pack, but would like to fly with 2 cells 1050mA. Airplane is 3D balsa profile at about 10 oz. or less.
"
You are probably right about the rewind. This 8-10 oz plane is my own design with full flying horizontal stab. It only has a 28" span, so I would prefer not to swing an 11 incher, although it will clear the ground. Would you care to make a wind recomendation for 2 cells? I have some of the gold Radio Shack stuff that's 24, or 22 ga I think.

I would like to try this delta, but not above 10 amps. Do you think I could keep under 10 amps on an APC 8 x 3.8 with this wind, only delta? I'm thinking the lazy method if it would work.

Rich
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Old Apr 27, 2005, 09:09 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
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Welp,
17 turns delta on an 8 x 3.8 makes a lot more thrust!

Wish I had a watt meter. It will hover at half throttle, but I only did it for a sec.

Anyone have any idea what kind of amps I might be drawing?
Rich
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Old Apr 27, 2005, 09:37 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
480 Posts
Just checked amps with a blue point clamp on. It's an automotive tool that ouputs 1 millivolt per amp.
8.4 amps! cool by me! I'll have to see what the flight durration is like.
Stupid tach batteries are dead! 4 hearing aid type!
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Old Apr 27, 2005, 10:13 PM
Crash Master
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Indianapolis, IN
Joined Sep 2001
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Slap: the speed is cut in 1/2 compared to a single, so this would be like a 20 turn single, as far as the prop goes. Sounds about right...
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Old Apr 28, 2005, 12:19 AM
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Corn Valley, Oregon USA
Joined Mar 2005
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My mini3DX is a pig and although I'm not sure exactly what is the weight, it's close to 10oz. It's powered by a GBx2 (double stator), 14T, 24awg pulls 6.5A w/ GWS1047SF prop. It'll 'hover' on a 2s1p lipo, but I've since abandoned it and fly with 3s1p lipos - Lotsa power, Lotsa pullout, and lotsa 3D tricks.
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Old Apr 28, 2005, 01:47 PM
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Slap,

Glad to hear that it worked out for you. That's probably a decent sized prop for that airplane. I've found that really big props + small planes = bad things. I would say that I think you could probably do a lot better though, you're currently producing about 62 watts but a double with cheese should be capable of well over 100 watts, I've heard as much as 150. So try that 3 cell batt and see what you think. Watch you're amps though!
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Old Apr 29, 2005, 10:59 AM
homo ludens modellisticus
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The Netherlands, GE, Nijmegen
Joined Feb 2001
10,788 Posts
Delta or wye makes no difference as far as motor character (Kv, Kt, power) and is concerned. A wye motor with N winds is the same as a delta motor with 1.7 times N winds. However, in a delta, large 'circular' currents may occur due to differences between the coils/phases (a delta is a closed circuit). This will effect efficiency and temperature. So, wye it is.

Vriendelijke groeten Ron van Sommeren
diy brushless motor group
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Old Apr 29, 2005, 11:39 AM
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Ohio, USA
Joined May 2002
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Hi Slappie-
Another possibility -- a GBx double with 13T #24 Wye on 3S makes about 115W with a GWS 10x4.7RS prop. That's about 11.5A, 6000 rpm, and 22-23 oz. thrust.

- Jeff
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Old Apr 29, 2005, 11:44 AM
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Its like deja vu all over again .
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Old Apr 29, 2005, 12:34 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
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Latrans,Gimp,
Thanks, I was really looking for options for this wind, as stators are cheap, I don't rewind, unless I wound something useless. Yes, I will follow the 13 turn recomendation on the next wind. I was thinking 22 ga., or would that be too much current?

Ron,
I keep reading how delta can be more effecient. You are saying that is false, and I understand why those differences could exist. So would it be better to use delta only on small prop, high rpm motors, or use wye for everything?

In this case, I can put this motor on a flying wing or something and run a smaller prop.

Switching the 17 turn 26ga. Wye to Delta did make the motor "usable"

Rich
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