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Old Feb 17, 2005, 11:10 AM
DWS
D.W. Schmidt
United States, IL, Scott AFB
Joined Sep 2004
311 Posts
Are outrunners more efficient at partial throttle

I thought I had read somewhere that while the high rpm/geared hackers and other such motors were more efficient at high power settings, the outrunners (such as the Axi brand) actually had an advantage when just cruising at half throttle. I realize this is more applicable to sport or trainer type aircraft, but is it true?

I am assuming in my question the same ESC and battery being used for both.

Thanks!

D.W. Schmidt
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Old Feb 17, 2005, 12:13 PM
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CharlieS's Avatar
Ithaca, New York, USA
Joined Jun 2001
357 Posts
I would like to know the answer to your question. It may be true due to the relatively high inductance of multi-pole motors such as outrunners. The higher inductance could smooth out the PWM by suppressing the higher harmonics, thereby reducing torque ripple and possibly other power absorbing effects. Anyone know for sure?

Charlie
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Old Feb 17, 2005, 01:59 PM
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United States, CA, San Diego
Joined Dec 1999
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Quote:
Originally Posted by DWS
I thought I had read somewhere that while the high rpm/geared hackers and other such motors were more efficient at high power settings, the outrunners (such as the Axi brand) actually had an advantage when just cruising at half throttle. I realize this is more applicable to sport or trainer type aircraft, but is it true?

I am assuming in my question the same ESC and battery being used for both.

Thanks!

D.W. Schmidt
The short answer is no. The issue is not simple--the controller plays a big part in this discussion.

Motor type is really not a issue.

One fun note--brushed motors (the good ones) often are better at part throttle.

Steve
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Old Feb 18, 2005, 08:57 AM
DWS
D.W. Schmidt
United States, IL, Scott AFB
Joined Sep 2004
311 Posts
Thanks Steve,

I seem to recall you wrote a couple of your columns in Quiet Flyer about partial throttle efficiency regarding different controllers. Any plans to do more tests or were the differences to small to worry about?

D.W.
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