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motor nmaking screeching sound at full throttle

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Old 10-20-2010, 08:39 PM
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garylkendall
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Default motor nmaking screeching sound at full throttle

i am new to electric flying. i have a question. i have gerneral hobbies yak 54, 46" wingspan, about 2 lbs i think. i have a turnigy 35-42 1250kv motor, a turnigy plush 80 amp esc (a little over kill), and am using 11.1v 2200mah batteries from hobby king, swinging a 11x8.5 prop. i programed the esc with a turnigy card mostly default settings. the problem i am having is that i went to fly it today and when i give it full throttle it gives a load screeching sound, when i back off the throttle some the sound goes away. i tried reducing the end point travel on the futaba radio i am using. this is all brand new equipment. the motor got very hot to the touch. i didn't fly it just ran it up several times trying to solve the problem. i had a problem with my other motor when i installed it. the motor had a short in it and burned up along with my plush 60 amp esc. didnt get to fly that one either, were brand new as well. any suggestions. why is the motor get so hot and making the screeching sound at full throttle? dont want to burn this up too. seen nothing but good revievs for turnigy as well. any help will be greatly appreciated.
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Old 10-21-2010, 09:29 AM
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Default RE: motor nmaking screeching sound at full throttle

If you advance the throttle slowly will it still screetch at WOT?
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Old 10-21-2010, 09:47 AM
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Jetdesign
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Default RE: motor nmaking screeching sound at full throttle

Sounds like a timing issue between your ESC and motor.

ESC sends only full-current pulses to the motor to control speed (on and off); faster pulsing results in higher prop rpm.

If the ESC is sending pulses to the motor at the wrong timing, it will be sending mixed signals of essentially forward and reverse. This would create a bit of friction and thus heat.

I don't know a lot about the different ESC and motor combinations - both of which are the basis for adjusting the settings.
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Old 10-21-2010, 02:49 PM
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Default RE: motor nmaking screeching sound at full throttle

Yes, it's probably a timing problem. There have been quite a few reports of such "screeching" episodes. Often, just increasing the timing will get rid of the screeching. Also, I'd try to measure the actual current draw you're getting with a wattmeter to rule out overloading. Excess heat in the motor or ESC is not a good sign.
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Old 10-21-2010, 08:27 PM
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garylkendall
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Default RE: motor nmaking screeching sound at full throttle

thanks timing was the problem, increased from low to medium. no more noises.
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Old 10-22-2010, 09:55 AM
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Default RE: motor nmaking screeching sound at full throttle

Interesting that relatively large motors seem to need higher timing to reduce screeching... in my experience most smaller motors benefit from lowering the timing!
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Old 10-22-2010, 11:58 AM
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Default RE: motor nmaking screeching sound at full throttle


ORIGINAL: Dr Kiwi

Interesting that relatively large motors seem to need higher timing to reduce screeching... in my experience most smaller motors benefit from lowering the timing!
My experience with ~2500W motors has eluded to larger motors running on low timing, a select few low-med timing. I think it has to do with more than size.
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