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brushless motors unwind?

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brushless motors unwind?

Old 01-19-2010, 07:40 PM
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1fasthitman
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Default brushless motors unwind?

Do brushless motors "unwind" while flying like a nitro or gas engine does? If so, does the current draw go up or down?
Old 01-19-2010, 09:25 PM
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hugger-4641
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Default RE: brushless motors unwind?

With any electric motor, as the rpm increases from start up, the current draw should decrease. As far as the difference in current draw between say 10,000 rpm during a climb and say 13000rpm after the plane is leveled out? I don't know how much the drop would be. Probably not much.
Old 01-21-2010, 11:55 PM
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wpotter6
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Default RE: brushless motors unwind?

Current on an electric motor is proportional to the load, i.e. torque being applied to the shaft. It is not a direct function of RPM. On the ground, if you hold the aircraft the load will increase with RPM and current will increase. When flying the load will be a function of RPM and airspeed. At a given RPM, if the airspeed increases the load on the propeller decreases. The opposite is true for a fixed airspeed, as RPM increases the load increases, this is why an aircraft climbs if you hold constant airspeed and increase the throttle. Of course there will be a dynamic relationship between RPM and airspeed that ends up balancing out for each trimmed flight condition.

Old 01-22-2010, 09:14 PM
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Default RE: brushless motors unwind?

Based on his question, I didn't think he was ready for the ohms law and dynamic resistance lesson, so I tried to give him a simple answer.

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