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Nov 17, 2018, 11:13 PM
Sokol
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Discussion

micro Nutball. 13" diameter.


here is a video, after switching to a 10g brushless motor (custom rewound, Y , 36 Turns per tooth, wire AWG 33, Kv= 635 ) ,
10 A ESC,
Battery 2S 300 mAh 30C,
APC 7*3.8 SF Propeller ,
FrSky 4 Channel RX.
two UMX Spectrum Linear Servos ,
82g AUW, wing loading = 3.16 oz/sq ft ,
Static test current draw at full throttle : 2.2A @ 8V , 17.6W into the ESC.

Flying outdoors, note the smoke from the "Camp Fire"

micro nutball - 10 g brushless motor - new propeller - Movie (3 min 0 sec)

micro nutball - 10 g brushless motor - new propeller - Movie (3 min 0 sec)
Last edited by JureZ; Nov 21, 2018 at 10:46 PM.
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Nov 17, 2018, 11:15 PM
Sokol
JureZ's Avatar
Thread OP
first video , using 6*3 GWS propeller, not powerful enough.
Micro Nutball Movie (0 min 50 sec)
Nov 18, 2018, 07:02 PM
Micro all the flying things!
Brainstorm's Avatar
Quote:
Originally Posted by JureZ
here is a video, after switching to a 10g brushless motor (custom rewound, Y , 36 Turns per tooth, Kv= 635 ) ,
10 A ESC,
Battery 2S 300 mAh 30C,
APC 7*3.8 SF Propeller ,
JureZ: Excellent Micro Nutball build!

It's very cool that you were able to rewind the 10g BL motor for 635KV. You must have used very skinny magnet wire to fit so many turns for the low KV. Kudos!

Would love to see pictures of the build and hear more details about the motor!
Nov 18, 2018, 07:20 PM
Sokol
JureZ's Avatar
Thread OP
Thanks Brainstorm !

the motor is https://hobbyking.com/en_us/18-11-20...___store=en_us

the wire I used was recycled from a transformer.
I tried a couple of times how many turns would fit the available window space , with the wire I had , AWG 33.
36 turns were just fine.I wired it using the Y configuration ( not delta, in that case Kv would have been 1100 RPM/V ).

Previously , I tried with a thicker wire but could fit just 12 turns, and the motor would not work reliably , because of the very high Kv , I think.

other details/ parts:
The plane was built using dollar tree foam, paper removed.
Glued with hot glue.
Two UMX linear servos.
A generic 10 A ESC.
A 4 channel FrSky receiver.

attached a standard size nutball drawing and a spreadsheet with the dimensions that I used.

Quote:
Originally Posted by Brainstorm
JureZ: Excellent Micro Nutball build!
It's very cool that you were able to rewind the 10g BL motor for 635KV. You must have used very skinny magnet wire to fit so many turns for the low KV. Kudos!
Would love to see pictures of the build and hear more details about the motor!
Last edited by JureZ; Nov 21, 2018 at 09:48 PM.
Nov 18, 2018, 08:35 PM
Sokol
JureZ's Avatar
Thread OP
some pictures of the micro nutball , as flown , are attached to this post
Last edited by JureZ; Nov 19, 2018 at 03:57 AM.
Nov 30, 2018, 04:09 PM
Micro all the flying things!
Brainstorm's Avatar
Quote:
Originally Posted by JureZ
the motor is https://hobbyking.com/en_us/18-11-20...___store=en_us

the wire I used was recycled from a transformer.
I tried a couple of times how many turns would fit the available window space , with the wire I had , AWG 33.
36 turns were just fine.I wired it using the Y configuration ( not delta, in that case Kv would have been 1100 RPM/V ).

Previously , I tried with a thicker wire but could fit just 12 turns, and the motor would not work reliably , because of the very high Kv , I think.
Thank you for the motor info, other details, and pictures!

One day I will learn about motor winding... I didn't know you could achieve lower KV with Y configuration instead of a delta wind. That's fascinating! It's especially useful for a fixed wing airplane, where there is usually more room for a larger prop than on a micro quadcopter, and low KV is thus especially useful.

Edit/PS: Reading through all your posts again, it's quite amazing that this tiny motor can drive an APC 7.0x3.8 prop on only a 2S 300mAh LiPo. That's really a model of efficiency! I imagine this would not be possible without the low-KV rewind.

Again, well done!
Last edited by Brainstorm; Nov 30, 2018 at 04:36 PM.
Nov 30, 2018, 10:13 PM
Sokol
JureZ's Avatar
Thread OP
thanks for the nice comments Brainstorm, much appreciated !
Feb 13, 2019, 04:15 PM
OCD: Old, Cranky and Disgusted
challenger_i's Avatar
Have received one of Jure's rewound motors, and it sure is sweet! Excellent workmanship!
Feb 13, 2019, 05:24 PM
Sokol
JureZ's Avatar
Thread OP
thanks Challenger_i !!!

I hope it works well for you.


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