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View Full Version : My experiences with two motor rewinds


shotgunsmitty
05-07-2008, 11:29 PM
Okay, so after Terra Firma repeatedly retired my RCU Bipe, I decided to put my Rhythm bipe together. Not thinking, I moved my setup over to the new plane and flew for about five minutes...then the motor stops and I have to deadstick her in. Problem? I had installed a new motor and the base mounting screws on the motor had come loose, causing the motor to twist in flight, while the main wires made contact with the windings and eventually either burned/melted through, or broke the thin 30ga wire. I put another motor on (another TowerPro 2408-21T and flew for about three minutes when that motor stopped, and she nosed into the concrete. Problem? Motor not just fried...fried!

I decided that since I have two motors that were bad to rewind them myself. Here are the results from my electrical checks this morning.

First motor, I used 30ga magnet wire and could only get about 19Turns on it because I'm not Chuck Norris. If I had watched a Chuck Norris movie the night before I might could have managed 20Turns...but 19 it is.

Prop: 7x3.8
17.56 Amps Peak
178.7 Watts Peak
10.07 Volt Sag
10200 RPM
322 Grams Thrust

I think this falls within specs. I might adjust my end point adjustment on my radio to keep the amps down below what my 15amp speed controller can handle.

Now the second motor...I only went 1/4 Throttle on this one. I used the same battery and everything, the only change was motor 1 to motor 2.

However, motor 2 utilized 22ga wire with only 9 turns.
It also had torque beyond belief.

Prop: 7x3.8
24.97 Amps Peak
255.6 Watts Peak
10.24 Volt Sag
RPM Unknown - Didn't want to risk it running 10 amps over my ESC.
Grams Thrust unknown, no RPM.

Why did my motors fry? I overpropped them and didn't realize it. I had been using a 9x4.8 and an 8x4.8 prop on my emax 2412 motor which was on the Bipe...this one could handle both of those props...I had done static checks on all of my motors these motors when I first got them and they handled everything well under the peak of the ESC...but when it came time to put the prop on the airplane, I grabbed the wrong one and consequently now have to repair my biplane and had to repair two motors due to my error.

Lessons learned.
But dang, two hundred and fifty-five watts out of a $14.99 combo from UH? And a five dollar investment in magnet wire from Radio Shack (which I have plenty left over).
Should I buy a bigger speed controller, say 30 or 40 amp and see how far I can push it?

CHELLIE
05-08-2008, 07:52 AM
Okay, so after Terra Firma repeatedly retired my RCU Bipe, I decided to put my Rhythm bipe together. Not thinking, I moved my setup over to the new plane and flew for about five minutes...then the motor stops and I have to deadstick her in. Problem? I had installed a new motor and the base mounting screws on the motor had come loose, causing the motor to twist in flight, while the main wires made contact with the windings and eventually either burned/melted through, or broke the thin 30ga wire. I put another motor on (another TowerPro 2408-21T and flew for about three minutes when that motor stopped, and she nosed into the concrete. Problem? Motor not just fried...fried!

I decided that since I have two motors that were bad to rewind them myself. Here are the results from my electrical checks this morning.

First motor, I used 30ga magnet wire and could only get about 19Turns on it because I'm not Chuck Norris. If I had watched a Chuck Norris movie the night before I might could have managed 20Turns...but 19 it is.

Prop: 7x3.8
17.56 Amps Peak
178.7 Watts Peak
10.07 Volt Sag
10200 RPM
322 Grams Thrust

I think this falls within specs. I might adjust my end point adjustment on my radio to keep the amps down below what my 15amp speed controller can handle.

Now the second motor...I only went 1/4 Throttle on this one. I used the same battery and everything, the only change was motor 1 to motor 2.

However, motor 2 utilized 22ga wire with only 9 turns.
It also had torque beyond belief.

Prop: 7x3.8
24.97 Amps Peak
255.6 Watts Peak
10.24 Volt Sag
RPM Unknown - Didn't want to risk it running 10 amps over my ESC.
Grams Thrust unknown, no RPM.

Why did my motors fry? I overpropped them and didn't realize it. I had been using a 9x4.8 and an 8x4.8 prop on my emax 2412 motor which was on the Bipe...this one could handle both of those props...I had done static checks on all of my motors these motors when I first got them and they handled everything well under the peak of the ESC...but when it came time to put the prop on the airplane, I grabbed the wrong one and consequently now have to repair my biplane and had to repair two motors due to my error.

Lessons learned.
But dang, two hundred and fifty-five watts out of a $14.99 combo from UH? And a five dollar investment in magnet wire from Radio Shack (which I have plenty left over).
Should I buy a bigger speed controller, say 30 or 40 amp and see how far I can push it?

Hi :ws: I always use a 30 amp ESC on my towerpro motors, since your rewinding them, use a 40 amp, on the towerpro motors, its a good idea to use some JB weld on the radial or stick mount to prevent them from turning, and use a little red lock tight on the set screws, I have had the towerpro motors turn on me too, not no more :D here is a real nice ESC from Heads up rc, I use them, and they are great, and not all that expensive, I like this post that was made today :D so I have to share it


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<HR style="COLOR: #d1d1e1" SIZE=1><!-- / icon and title --><!-- message --><CITE class=smallfont>Originally Posted by Dr Kiwi</CITE> http://www.wattflyer.com/forums/images/buttons/viewpost.gif (http://www.wattflyer.com/forums/showthread.php?p=404086#post404086)Just so you know - the ESC is simply a "dumb animal" which doesn't determine the power to the motor - the ESC simply lets through whatever the motor/prop demands. If the ESC is big enough it is happy, if the ESC is too small it fries!

Well Said :D :D :D
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http://cgi.ebay.com/POWER-UP-32A-ESC-Brushless-Motor-Speed-Control_W0QQitemZ220231264090QQihZ012QQcategoryZ34 056QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1 262

Jeff also has a 40 AMP ESC with a 3 AMP BEC, he is out of them right now, Heads up rc is a safe E Bay Store, lots of Wattflyers buy from Jeff, Tell Jeff, Chellie sent you :ws:

CHELLIE
05-08-2008, 08:05 AM
Hi Again :ws: If you have a chance, try this motor, its the Turnigy 2830, I replaced a TP 2410-09 in my Slow Stick with one, and it felt like it has almost twice the power :D and its only $9.95 this is a one do it all motor, as you can just change props for what ever plane you want, I Use a 11x4.7 in my slow stick, and any smaller prop than that will work great, a 9x7.5 prop will make a GWS type war bird scream, My friend flew this motor in 20 to 25MPH winds in his plane, and it cut right through the wind, this is a nice powerful motor, if you order it, dont use the expensive shipping charge Hobbycity has already checked, use the least expensive shipping, its Airmail, also use PayPal to be on the safe side, when buying from over seas, you will get your money back if it gets lost, take care, Chellie



http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=2111

here is another version of the 2830 turnigy motor

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=2112

shotgunsmitty
05-08-2008, 08:37 PM
Chelli, I've been waiting to hear a review on that motor. They're out of stock at the moment, but I think I'll go ahead and order one. I don't really need the bells and whistles package that the second link offers, but I'm certain that I can make good of that motor. Besides, I really need something else from them...I don't know what it is, yet, but I'm sure I do! I think I need some crystals.

I read that message yesterday about the esc being a dumb animal, and I liked that, too. I did order a 30 amp yesterday, found one on sale for 16 bucks delivered. Couple that with a ten dollar motor and we're looking at a power plant minus battery for about 30 bucks...and not too shabby of one, either, from what you say. Those are great tips on buying from Hobbycity, too, btw. And although I do exactly that, I'll score you a thank you for it.

I put the biplane back together yesterday and mounted the 30ga 19T. I think if I stay out of full throttle and remember to put the proper prop on it I should be fine.