At 12:35 PM 7/23/2002 -0400, you wrote:
>Hi all,
>
>I've been looking at electric motors for use in small autonomous flying
>vehicles (I do research in these at Cornell University) for some time. I
>have been using the ratio of maximum rated output power per gram of weight
>as a figure of merit for motors. Typical high-end RC electric flight hobby
>motors (like the Pelikan AXI motors or Astroflight motors) achieve around 2
>Watts/gram. The best high-quality industrial motors I can find (like those
>from Maxon or Micro-Mo) achieve about 10 times less (0.2 W/gram)! I have
>been trying (to no avail) to find out why there is this discrepancy. I am
>an RC hobbyist myself and I have a great respect for what is achieved in
>the hobby world, but I do find it hard to believe that the hobby world is
>able to achieve motors that outperform the best industrial motors by a
>factor of 10 in some regard. I'd like to find out if perhaps there is some
>other drawback to the hobby motors or if perhaps they arrive at their
>maximum rated power spec differently which would explain part of the factor
>of 10.

I would have to guess that the RC motors are designed to give as much power
as possible while keeping the weight down to a minimum. So the casing is
probably lighter in weight, and the bearings are probably not as heavy as the
industrial counterparts, but I would bet that are also not designed to run 24
hours a day, 365 days a year.

I know for a certain that the industrial motors are designed to survive in an
industrial setting and run continuously all year. Weight isn't an issue when
your motor is staying on the ground (unless you are talking about some huge
generator motor).
_____________________________________________________________
Cris Wilson
Information Resource Consultant
College of Architecture, Arts, and Humanities
Clemson University
cris@clemson.edu
To report problems email: aah_computers@clemson.edu

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