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Old Apr 29, 2009, 09:55 PM
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RWCLOUD's Avatar
Fresno CA
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Pushing a Turnigy 2836-3700 past its limits

First a little history , I've been building and flying Foamies for 4 years now and Gliders and glow since 1980. A couple of years ago I started playing around with EDF's. Last month I made my first GoBrushless kit motor and it works great! Now I want to go further............

I bought a Turnigy 2836-3700 with the intention of using it in an EDF. A RCMart 70mm fan. The HC site says it can make 750 watts . I ran it up in a test stand with a borrowed XPS 3200 mah 4s pack 30c. the motor hit 1000 Watts and made about 54 ounces of thrust at about 70 amps.But it smelled a little warm I put it in an orignal design of mine that I call " Silver Cloud" . Went to luanch it and nothing ! Unpluged the Battery and tried it again and black smoke poured out of the exhust tube Both the motor and ESC were fried ( 80 amp SPT )

Since I bought the motor with the thought of perhaps rewinding it now I get my chance.

This is only my second rewind and I've been doing a lot of studying but don't have all the answers yet. First I tried winding it as close as I could as stock, it had 5 turns with 11 strands of 32 AWG wire. I have some Radio Shack 30 AWG wire so I tried it with 10 strands , still 5 turns. Motor ran very smooth. holding it by the wires, much quiter than the factory wind. Ran it up on the test stand , stiill 1000 watts ,etc. but the motor smelled a little warm , but the case was not even warm.

Here's my question, would using High temp wire from MicroDan and high temp Magnets from Inov8ite Designs work as to deal with the heat? Or should in addition to the wire and Magnets should I use larger guage wire with fewer strands?

BTW this motor weighs 70 grams , so 1000 watts = 14.28 watts per gram. HC says that its supposed to live at 10.71 watts per gram and I don't doubt it if it were in an EDF.

Blue Skies...............R Dub
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Old Apr 29, 2009, 11:02 PM
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manuel v's Avatar
Mexico, BC, Mexicali
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R dub.

11 strands 32awg is around 1 22awg. good for 32A in EDF.
10 strands 30awg is around 1 20AWG. good for 50A in EDF.

Put 6turns 20AWG for 3000kv. for around 700 watts.
50A max.

http://www.rcgroups.com/forums/showthread.php?t=1032139



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Old Apr 29, 2009, 11:27 PM
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Thanks Manuel.

Yes I saw that thread, and it looks nice , but I really want to keep the Kv up to around 3500 to 3700 and make 850 - 900 watts. I know that this is a tall order , but I want this model to go straight up from launch!

What about winding a Half turn? Is it possible to wind 5 1/2 turns ,with say 5 or 6 strands of 24 or 26 AWG wire ?


This is the unfinished model that I plan to use this motor in

http://www.rcgroups.com/forums/showthread.php?t=932610


Blue Skies ..............R Dub
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Old Apr 30, 2009, 12:03 AM
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League City, Texas
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I would listen to Manuel. I also have this motor and it really is just too high of a KV on 4S in a 70mm fan. You need to lower the KV to something like 3200. I had this motor in a HET 6904 and saw over 40amps at half throttle. I took it out and slapped in the KD450H and it works like a champ.

http://www.hobbycity.com/hobbycity/s...idProduct=5246

Steve
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Old Apr 30, 2009, 02:12 AM
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R-Dub.
5.5 turns is for for 3360kv. but is very mush for 4s. maybe is fine in 64mm edf.
for 70mm fan to around 1000 watts is necesary a big motor.

I think max 3000kv. and 6 turns. o 5 turns and 64mm edf.

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Old Apr 30, 2009, 08:45 AM
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BTW this motor weighs 70 grams , so 1000 watts = 14.28 watts per gram. HC says that its supposed to live at 10.71 watts per gram and I don't doubt it if it were in an EDF.

Interesting - Louis Fourdan must be having a heart attack, since his recommendations are typically around 3W/g! Yes, I know you can push a bit more through an EDF, but still.............
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Old Apr 30, 2009, 04:19 PM
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Steve , I agree that the KDA450H is a great motor in the 6904, I have one, but in our neck of the woods thats a low powered set up.

Manuel , these days we are pushing 70 mm fans past 1400 Kw , the JS 1400 and 1490 do the job very well ! But they weigh to much fo the application that I want to use it in, bigger motor, bigger battery , endless circicle. I wish I could find an 28 mm outrunner that weighed around 100-110 grams.

But I still do not know how to wind a 1/2 turn

Dr. Kiwi .................Ya Think !!!! Thats why I'm wondering about high temp wires and managents. Since it would only briefly run at WOT and then the rest of the time about 35 to 40 amps , perhaps I could get away with it.


Blue Skies..................R Dub
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Old Apr 30, 2009, 05:25 PM
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Of course, we have the paradigm of 3 watts per gram. and in normal applications, it is almost impossible to pass.

Here's a comparison I ran some time ago. All with a GWS 10x6HD (thanks Hoppy data)

Motor -------------- Watts ----- Volts -----RPM----weight----Effy----Watts/g-----%kv.
HackerA20-20L#1......161............10.3........7800----58g-----66.8---- 2.77 ------71.6
HackerA20-20L#2......164............10.3........7860----58g-----67.1---- 2.82 -------72.2
KDA22-20L(1)...........166............10.29.......8310----85g---- 78.4 --- 1.95 ----- 73.3
KDA20-20L(1)*...........140............10.6........7500---85g ---- 68.2 --- 1.64 ---- 64.2
Suppo 2217-08(2).....162............10.03.......8500----70g ---- 86.1 ----2.31 ----- 77.0
KEDA TR2837/14(3)...178............10.7.........8520-----81g---- 78.9---- 2.19 ---- 74.4
Suppo 2217-08 (4).....222...........10.7.........9030----70g ---- 75.3 ---- 3.14 --- - 76.7
HXT 750(5)*...........208............10.07........8800 -----80g ----74.5 ---- 2.6 ------ 83.3

(1) Hobby City
(2) Lightflight RC
(3) Dr Kiwi's motor results from above.
(5) Rewind to 13t, 21awg. 1049kv. Manuel V.



But speed applications and applications especially in well-ventilated, the picture changes.
to where?
The EDF provides an excellent ventilation and would be very interesting to know the limits.

ABC wind, you can not turn to 5.5. Sorry.
would be 5.5 in the first tooth, 5.5 in the second and 6 in the third.
If you want to experience this configuration, after the 5th round, and give half back pass the wire through the top to the next tooth (4) and at the end of the fifth round, half spend more to turn it down to the wire and from there go to the next tooth (7) you can make 5 or 6 full turns.
DLRK in an easier, das 6 laps in a tooth and the adjoining 5 and ready.


If you use an extension of the Little screamer, you will have better ventilation and a better possibility. Additional well the metal will help to dissipate heat more than anything.
High temperature wire and a packed high with thick wire a little more help.
Of course better and much effort to enhance design efficiency. but that would be expensive and possibly more difficult.

For 1000watts 4s. i think in a eficient motor 120-150 grames.


Manuel V.
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Last edited by manuel v; Apr 30, 2009 at 10:22 PM.
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Old Apr 30, 2009, 07:16 PM
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League City, Texas
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I have a JS 1400 as well and it's a beast, but you just aren't going to get 1400kw out of that Turnigy. Tailslide seems to have a nice setup here with the ARC and 6904 combo.

http://www.rcgroups.com/forums/showp...postcount=7229
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Old Apr 30, 2009, 08:22 PM
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Steve , Thats just it , I'm not trying to get 1400 watts out of it , just 900 - 1000.

Yes Glenn has a nice set -up there. But with the app that I'm going to run , the RCMart Fan is the better choice. Just need to find a way to keep the weight down and watts up !
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Old May 01, 2009, 12:13 AM
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I tested a Turnigy 2836-2350 (actually 2800Kv) and it got too hot to hold at ~400W... hmmm!

By the way... how did you get rid of 11g... you say 70g... my stock motor was 81g?
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Old May 03, 2009, 11:06 AM
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Can some one please measure the magnets, are they curved.

Thanks
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Old May 03, 2009, 11:24 AM
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United States, VA, Bedford
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Quote:
Originally Posted by Dr Kiwi
By the way... how did you get rid of 11g... you say 70g... my stock motor was 81g?
He might have taken his measurement after he removed the wire..

-Shawn
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Old May 03, 2009, 02:11 PM
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Sorry , Iv'e been doing other projects. To make matters worse this project will be on hold for a few weeks, mainly because my new ESC is on back order. And I've noticed a small vibration in the motor, it turned out to have the end bell drilled at a slight angle , causing the bell to wobble , so I've ordered a new one. At this piont I'm kinda wondering if I should have bought a Scorpion to start off with and tortured it?

Dr. Kiwi , sorry I missed your question, I don't know , my scale says it weighs 70 grams , thats with the current wind on it. Just checked my scale and it says 5 quarters weigh 1 ounce , so it should be close enough.

The magnets measure 18.4 mm long x6mm wide x 1.5 mm thick at the thickest part , ( the out side part is curved , the inside part is flat ) and 1.3 mm at the skinney part.

Hope this helps

Blue Skies ................R Dub
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Old May 03, 2009, 05:00 PM
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thanks
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