I have been looking at some of the web sites and am very confused about
what motors go with what size planes. With Glow engens it is a simple
mater of knowing if it is 2 stroke or 4 stroke and what the displacement
is. I can't seem to see any standard size indicators for the electric
motors. Can some one give me a good primer on electric motor
Welcome to the wonderful world of electric flying. You have quickly
discovered one of the problems of electrics, and frankly, there is no real
easy answer. Depends on the motor type, battery output, prop selection, and
a few more variables. Getting the right match between the airplane and the
power combination is "the secret" to getting an airplane which really
performs, vs one that staggers around the sky.
That said, some of the best advice I can pass along is to take a look at a
really great source of information which is available on
http://www.rcgroups.com and select the electric forum. There is a wealth of
help available there and you'll see pictures of a lot of electric models.
The people are very gracious about sharing their experience. You'll be
reading for a month of Sundays!
It is a great spot, hope this helps you figure out what you need to know.
In general,. the only clear guideline is to look at teh typical current
draw of the motor, the number of cells it likes, and work out how many
watts that is. Then use the '50W/lb for reasonable flights' to get to
how heavy a model it will fly.
If yopu have a specific queriy, opst it here, and I will try and pass on
such knowledge as I have, but there is no 'simple formula'
Well, currently I use 2 types of motors in all of my 7 planes. The main
motor is the speed 400 motor, which are very cheap and provide decent power.
A single speed 400 engine direct drive plane has about a 30 inch wingspan
and weighs roughly 1-1.5 pounds. Of course this varies but it is a good
approximation. I usually fly these with 7 or 8 cell packs of 1000mah NIMH
cells. For direct drive on the speed 400 you are usually going to use about
a 5x5 electric propeller. Of course this also varies but not by much with
the cheap can motors in a direct drive setup.
The one plane I have that is dual speed 400 drive weighs 2 pounds, and uses
8 cell 1950mah NIMH cells. It has a 5 foot (60 inch) wingspan.
The second motor I use is the GWS IPS motor. These are meant for planes
that weigh around 8oz. They are geared and come in various gearing ratios
for various applications, but I won't get into that. I have flown them on
6-8 cells of 720nimh, 350nicd, 350nimh etc, and for their amazingly small
size they are pretty powerful.
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