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speed controls

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Old 06-15-2013, 06:51 PM
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handeman71
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Default speed controls

Hey guys, I got a question about electrics. I have a reactor bipe with a rimfire 35-36-1200 motor. With the design of the cowl and the spinner it really doesn't allow any airflow directly into the motor. I have now burned up the second motor. The motor says max surge is 55amp. I always go overkill with speed controls so they don't burn up. I believe I have a 60 amp esc on it. Never had a problem with any other planes with oversize speed controls. Was wondering if the spinner is causing lack of airflow or the oversize speed control might be causing the motors to overheat and burn up? (It still turns free by hand but will not run and made horrible screeching noise in air as if prop came loose but didn't and saw slight smoke trail for a second. Was very, very hot)
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Old 06-15-2013, 07:33 PM
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Walt Thyng
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Default RE: speed controls

Head room on an ESC will NOT cause a motor to burn up! Lack of airflow is what's doing it. Also the air exit next to be at least twice the area of the inlet.

Sadly, I burned up a motor this weekend while trying to taxi thru to long grass. Airflow was sufficient for flying, but not for mowing grass )-:
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Old 06-17-2013, 06:04 PM
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Glacier Girl
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Default RE: speed controls

Walt has it right. Looking at a picture of it, you could add an intake below the motor, use a duct to have the air flow up towards the motor. And like Walt said you need two times the exhaust area compared to the intake to make it work.


Was like my P-40, had a big old chin intake, but all the airflow was way below the motor. Simple piece of lite ply to redirect the airflow made a world of difference in it.
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Old 06-19-2013, 09:08 PM
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Default RE: speed controls

First of all, why do you have a 1200kV motor in that airplane? A quick search of the Reactor Biplane took me to Great Planes site, where they recommend a 500kV motor, 3S lipo, and a 60A esc. Is this the right airplane? How many lipo cells are you running? My gut reaction is you have a bad setup.

If I'm missing something, maybe it's the timing setting on the ESC. Mismatched timing setttings usually result in loud screeches in the air.

60A ESC is not 'overkill' for a 60A system. 80A or 100A would be overkill. 40A would be too small, 60A is marginal.
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Old 06-24-2013, 02:18 PM
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Default RE: speed controls

You need to use your watt meter before you even put it in the air, guessing dont get it. you could be easily drawing 50 or more amps constantly. what size prop are you spinning?
It says max surge is 55, max constant is on 45.

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Old 06-24-2013, 02:52 PM
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Default RE: speed controls

I usually go overkill with size of motor and speed control. I believe the .15 and esc is matched. I am convinced that the spinner is so close to the shaft opening that it completely covers the direct inlet to the motor coils and causes it to build up too much heat. Just going to have to use a spinner nut to allow air to freely flow over coils.
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Old 06-24-2013, 02:56 PM
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Used a recommended 10 x 7. Had a meter somewhere but never learned how to use it. Am convinced the spinner is blocking direct airflow into the coils. It divert air around the sides.
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