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Old Mar 14, 2009, 11:34 AM
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United States, NJ, Frenchtown
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HEAT>>>HEAT rejection ???

Plastic pipe is death to the motor. If I visualize the tube in a tube description correctly.

I did industrial upgrades for a living. How are you going to move enough air thru & around the motor in a fixed in position use ? Airplane motors are rated at typical flying speeds.......Some flying speed with good air movement.
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Old Mar 14, 2009, 12:55 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
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Quote:
Originally Posted by Bruce Abbott
They do (in a poorly designed motor that doesn't have enough back-iron).

http://www.rcgroups.com/forums/showthread.php?t=953949

That is astounding. Never gave it a thought. Glad I use PU impregnated paper tubes now.
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Old Mar 14, 2009, 02:11 PM
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On similar lines, using plastic instead of aluminum for the stator carrier (bearing tube) can noticeably improve the performance of an outrunner motor in some some cases.
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Old Mar 14, 2009, 02:26 PM
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USA, AZ, Tucson
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I am using helicopter versions of the motor with built in centrifugal blower. At 8000 rpm the motor sucks quit a breeze through the windings. The motor itself was running quite cool, just the copper pipe was heating up very quickly. The original motor had a centrifugal blower attached to cool the same way.

The epoxy laminate fiberglass I ordered is rated to 510 F. The epoxy I will use is rated to the same temperature.
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Old Mar 14, 2009, 02:31 PM
7000mw of raw power!
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New Hampshire (not the old one)
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I noticed the aluminum stator tube seems to get hotter than the windings. I wonder if CF tube like the Westport kits would improve things.
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Old Mar 14, 2009, 02:46 PM
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You realize that the motor has almost NO metal holding all of the magnetic field in side of the motor ? I would just take the easy way out with non-metallic........ METAL. .....Should now be a known shortcoming of outrunners ??
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Old Mar 16, 2009, 10:12 AM
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I guess the question is whether the lack of iron in the rotor of the outrunner will cause a loss of efficiency at higher currents (higher magnetic fields) or a saturation point of the iron rotor where the motor will draw more current but not provide more torque.
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Old Mar 16, 2009, 10:37 AM
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Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by leybold12
I guess the question is whether the lack of iron in the rotor of the outrunner will cause a loss of efficiency at higher currents (higher magnetic fields) or a saturation point of the iron rotor where the motor will draw more current but not provide more torque.
More than anything, the thin rotor iron will result in lower peak power output before the motor runs into saturation. Then it will draw excessive amperage with little or no power gain as you described. Efficiency usually isn't affected that much. Maybe 1-2% at most.

-Alex
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Old Mar 16, 2009, 11:08 AM
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I guess I have to beef up the dyno so I can draw more than 30 amps off the motor to see the saturation point.
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