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Old 04-21-2007, 11:11 AM
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aeajr
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Default RE: Electric suggestions

SELECTING ELECTRIC POWER SYSTEMS
Reference Resources

Electric airplanes can be lots of fun and very little work. There are lots of
RTF planes that already have their power systems selected and installed.
They require no work at all on your part. That is about as easy as it gets.

If you like ARFs or kits, many come with motors and props standard. Some will
include a gearbox as well, if the designer considers that the best approach.
While these may not be the most powerful motors you might put on the plane, you
can be reasonably confident that they will fly the plane. The instructions will
normally recommend an appropriate sized electronic speed control, ESC, and
battery pack to use with that motor and propeller combination on that plane.
Just read the friendly manual, RTFM, and you can usually get the plane in the
air with little trouble. That is still pretty easy.

But what if you want to design a power system yourself. Perhaps you are
converting a glow or gas plane over to electric power. How would you go about
doing something like this. This is not a trivial task. There are many factors
to take into consideration and there are hundreds of motor, ESC and battery
pack options out there. How do you choose?

Or say you want something better or stronger than the motor that came with your
plane? And, of course, some ARFs and kits don't include motors. And finally
there is the fun of designing your own planes. Now you need to plan the power
systems.

If you are going to design your own systems you will need some help and some
knowledge. What I have compiled is a list of links that take you to resources
to help you. First I recommend you read this article for background
information. It will help you understand and use the rest of the resources
listed below.

Sizing Electric Power Systems -
http://www.rccyberflyer.com/forum/showthread.php?t=272

Remember that the system operates as a whole. If you have the right motor
with the right battery and put on the wrong prop, things can get pretty ugly
pretty fast.

I highly recommend you pick up a wattmeter. If you are going to be a designer
there are only two ways to know if you got it right. The first is to measure
the
amps, volts, watts being drawn by your new power system and making sure all
components are up to the effort. The other way is to see the plane fly badly,
watch your new motor burn up, your new battery pack fail or see the magic smoke
come out of your ESC. Personally I would rather you get a wattmeter. This
thread discusses their value and uses. Several are discussed.

WATTMETERS - Vital to the power system designer
http://www.wattflyer.com/forums/showthread.php?t=11863


Brushed vs. Brushless motors

Many RTF, ARF and Kits come with brushed motors. These are often identified by
a "speed:" designation such as speed 280, speed 370, speed 400, speed 600 and so
on. They work fine but are less powerful and less efficient than brushless
motors. If you are going to design your own power systems I suggest you go
directly to the brushless motors. Prices have come down a lot and quality, even
at the low end, is good. So leave the world of brushed motors behind and go
brushless. From this point forward I will only be looking at brushless systems.

Resources

Some manufacturers have done a good job of providing tables and charts that can
help you use their components to come up with the right system. Armed with the
knowledge from the first article you are now better equipped to use them. The
ones I have found most useful are next.

Some retailers have also gone to a package approach to take the guesswork out of
the effort. They combine a motor, ESC, mounting hardware in to a package. Some
include battery pack recommendations and may also provide wiring options as
well.

MAXX PRODUCTS

Maxx Products - How to Choose a Brushless Motor for an Airplane
pretty good tip sheet on coming up with a glow to electric power comparison.
http://www.maxxprod.com/mpi/tips3.html
HiMaxPower System Packaged sets and info chart
Motor, speed control and prop all matched up for you
http://www.maxxprod.com/mpi/mpi-264.html


ELECTRIFLY

Guide to Glow to Electric Conversions
http://www.electrifly.com/manuals/gp...-elec-conv.pdf
Electrifly Electric Motor Configuration Tool
It assumes you know where you are going. Read the article above and you will be
better prepared to use this too.
http://www.electrifly.com/config/
Brushed motor to Brushless Motor Conversion Chart
The recommendations will yield a significant power boost.
http://www.electrifly.com/powersyste...brushless.html
Chart of Sample Planes and Recommended Power Packages
http://www.electrifly.com/powersyste...nversions.html
Electrifly Brushless Brochure. Lots of useful info that you can print out.
It is only for Electrifly components, but it is well done.
http://www.electrifly.com/sellsheets...m-brochure.pdf

GWS

GWS provides excellent information about their brushless motors and how they
perform with different batteries, and props. Useful, once you understand the
watts/pound rules.
http://www.gwsus.com/english/product.../brushless.htm

SkySharkRC

Prepackaged Electric Conversion kits for .50 and larger glow planes
Includes Motor, battery, ESC, mounting and connectors
http://www.skysharkrc.com/shop/?shop...27&cart=125763

Hobby-Lobby

Packages Glow Planes with appropriate electric conversions. This can be an
excellent source for the whole thing, or you can use their conversion as a
reference for your own conversion planes.
http://www.hobby-lobby.com/glowtoelec.htm

In addition, Hobby-Lobby provides excellent information about the motors they
sell often providing motor, prop, battery stats to guide you in picking your
own components. Their on phone sales people are very good and have excellent
resources to back them for designing electric power systems.
http://www.hobby-lobby.com/brushless-motors.htm


Other Resources

A series of posts on electric power system basics
http://www.wattflyer.com/forums/showthread.php?t=1933
http://www.rcgroups.com/forums/showthread.php?t=417868

MotoCalc will tell you everything you need to know: Amps, Volts, Watts, RPM,
Thrust, Rate of Climb, and much more! It is a popular tool for predicting the
proper motor, prop, battery pack for electric planes. Read the fist article
first and this will make a lot more sense.
http://www.motocalc.com/

Amps vs. Volts vs. C
http://www.ampaviators.com/index.php...d=37&Itemid=27

Low Voltage Cutoff
http://www.wattflyer.com/forums/showthread.php?t=3445
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