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Volt,Amp,Watt,RPM,Windings......

Old 01-31-2003, 06:44 PM
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hdebruin
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Default Volt,Amp,Watt,RPM,Windings......

Hi All,

I have belonged to the loud and messy tribe for a long time now. And am now
faced with having to switch to electrics if I want to continue flying.
Now with glow engines, I pretty much had an idea about how big an engine
could haul how big an airplane. Cubic inch is easy.

Not so with electrics. Everything seems related, and it looks to be near impossible
to figure out an exact match for a given model.

So what I'm looking for is websites that can teach me the basics behind engine selection, brushed or brushless, nr of cells, geared or non-geared, prop sizes etc etc. Most of all I am intriged by the term 'windings'. This term seems to be the
holy grail that only a select few seem to know the ins and outs of. I want to
learn that too.

What I did already find out is that electric engines are far more dangerous than their glow powered counterparts. My little finger can tell a story about that.

Greetings,

Hans
Old 01-31-2003, 09:20 PM
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Tippie
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Default Volt,Amp,Watt,RPM,Windings......

Try this web site: http://members.aol.com/KmyersEFO/index.htm Click on 'site table of contents'. This is loaded with electric information. Also you may want to take a look at a computer program called 'motocalc'. It will give you a pretty good analysis of what is needed to power a specific airplane. You can download the program and use it for a 30 day trial. After that they want you to pay $36.00 USD for it. A lot of the serious people use it and although I don't have it myself I am considering it. Go to: www.motocalc.com and have a look. Did anyone tell you that you don't have to "prop" an electric motor. HA The other warning is always be alert to props when you turn the receiver on, you may have the throttle advanced and will give you a wake up call. Some ESC's have a safety on them that requires you to advance the throttle to full and back to off before it is armed. Reduces the surprises.
Welcome to electrics, I'm learning about it as well and do web searchs ( www.google.com ) to cram info into my empty cranium. You might also go to the all electrics web site: www.ezonemag.com and get registered into their discussion forum.
Old 02-01-2003, 09:58 AM
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Steve Lewin
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Default Volt,Amp,Watt,RPM,Windings......

And while you're at the EZone don't forget to have a look at the Electric Flight FAQ. Lots of good information collected in there.

It won't tell you much about "windings" because it's only car guys that talk about those all day long. They're mainly of interest if a) you want to design your own electric motor from scratch or b) you are stuck with one size of motor and have to fiddle with the internals to change power etc. For electric flight we just look at the electrical characteristics of a bunch of motors (using Motocalc or something similar) and choose the appropriate motor.

Steve
Old 02-01-2003, 08:46 PM
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hdebruin
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Default Volt,Amp,Watt,RPM,Windings......

Thanks guys, I'm diving in head-first

Hans
Old 02-01-2003, 09:00 PM
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hdebruin
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Default Volt,Amp,Watt,RPM,Windings......

Originally posted by Steve Lewin
It won't tell you much about "windings" because it's only car guys that talk about those all day long.
Steve
<comes running back from EZone>

Dang ! You is a celebrity ;-)

Yes, I don't want to start winding myself, but doesn't the nr of windings in a stock motor say anything about its torque, rpm, amps, volts whatever to be able to match it to a certain airplane ? Like with an IC engine the bore/stroke ratio says something about an engines performance, even if I don't intend to build one myself.

Anyway, lots to learn.

Hans
Old 02-02-2003, 02:57 AM
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Tippie
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Default Volt,Amp,Watt,RPM,Windings......

Try these two threads to see if they answer your question about windings.
http://www.rcgroups.com/forums/showt...threadid=14148
http://www.rcgroups.com/forums/showt...threadid=65245
If I didn't make a typo the URL's should work.
Yes, # of windings are a factor of motor input/output. The windings will determine current draw and power consumption. True, windings are usually not mentioned for electric motors used with rc airplanes as much as they are for rc electric cars. Airplane motors specs usually cut to the chase and are specified as to current draw, voltage, torque, physical size, etc. If you go to the "Kmeyers" site I gave you, you can find a good list of various motors with these specs. You may also find the info by doing a "search" at the 'power systems' site in Ezone. The URL's I gave were from a search I had made by entering "electric motor windings".

Oops, made a typo but should be corrected now.
Old 02-02-2003, 10:11 AM
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Steve Lewin
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Default Volt,Amp,Watt,RPM,Windings......

Simplified view of windings (or turns).

If everything else is the same, i.e. motor size, # of poles, brushed/brushless, strength of magnets etc and the voltage you're using :

More turns = lower current, lower revs, better torque
Less turns = higher current, higher revs, low torque

So typically for the cheap Speedxxx/RC car-type motors:
higher turn motors will turn bigger prop without taking too much current and without a gearbox

Lower turn motors can only turn a small prop direct drive so are usually used with a gearbox.

Steve

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