stunthanger.com
Electric Stunt => Gettin all AMP'ed up! => Topic started by: Ken Burdick on August 21, 2017, 08:32:22 AM
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Mark Ruddner posted a picture in the New England combat journal
https://mail.google.com/mail/u/0/#inbox/15e050e031f4f8b9?projector=1
of a F2D lectric ship that uses an "in-runner" motor......says it has less rotating mass. Since most of this stuff seems to be in acronyms and code, can anyone tell me what this one is?
Thanks
Ken
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Uh -- that's a link to your email account. When I click it, I go to my email account, which doesn't get emails from the NE combat journal.
An in-runner is a brushless motor that has the magnets on the shaft, and the coils on the outside of the motor. The "in" goes with the magnets. An out-runner is a brushless motor that has the magnets on a bell that turns with the shaft on the outside of the motor, and the coils on the inside.
Inrunners spin faster, and are actually more efficient at turning electrical energy into mechanical energy at the shaft -- but they do so at speeds where propellers aren't efficient, unless you're trying to go as fast as you can. 20 years ago the solution to the efficiency problem was to run a gearbox -- but someone smart figured out that if you turned a brushless motor inside out you got something that was lighter, more robust, and more efficient than an inrunner + gearbox. That's an outrunner.
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To look at is as rotor/stator combination. The rotor is the moving, rotating part typically used for output power. The stator is the fixed, stationary part typically fastened to the structure.
The in-runner has the stator as the outer can with the rotor as the inner shaft for output.
The out-runner has the stator as the inner shaft with the rotor as the outer can for output.
How the motor is build, wound, and wired is different from in-runner vs out-runner. With _brushless_ motors the winding are _always_ on the stator and the magnets _always_ on the rotor.
This is not the only way motors are built if you start looking at cheapo DC motors to industrial motors, but that is probably outside this discussion.