Terry Gamble
Apr 01, 1996, 01:00 AM
<html>
<head>
<title>How To Break-In an 05 Can Motor</title>
</head>
<body bgcolor="#FFFFFF">
<pre>Important...Break in Your New Electric Motor
My experience with inexpensive 6-7 cells electric sailplanes has convinced
me that an important building step is properly breaking in the electric
motor. I have seen a few of these airplanes that give very lackluster
performance and one example of an airplane that took a fully charged pack
just to reach about 200 feet. The owners invariably conclude that electric
flight is impractical because the airplane is too heavy. This seems a
logical conclusion because their motor comes on when they push the
throttle stick just like it's supposed to. It doesn't occur to them that
the motor could be the problem.
These inexpensive ferrite motors are very inefficient at converting
electrical energy to thrust. Even a good one is pretty lame compared to a
more efficient cobalt motor. Therefore, we need all the power we can
squeeze out of them. The reason we bother with them at all is because they
are so inexpensive they are practically expendable. Properly set up, they
do an acceptable job of pulling our sailplanes to altitude, and the price
is very attractive to beginners. They are a good way of "testing the
waters" of electric flight without spending a fortune.
I have weighed a couple of these doggy airplanes, and found that they were
no heavier than mine. I have also used the owners battery pack to insure
that the problem isn't a weak battery. I was left to conclude that the
motor was the culprit, and several "experts", including Hobby Lobby back
this up.
A two meter electric sailplane typically weighs 50-55 oz. You should
expect to get 2 1/2 to 3 climbs to about 500 feet out of a typical 1400 ma
R/C car pack. Or, you can get about a dozen climbs to 100 feet, depending
on your preference. Interestingly, it doesn't matter very much whether you
use a 6 or 7 cell pack. The 7 cell pack makes the airplane climb faster,
but it doesn't seem to have much bearing on total altitude gain. If you're
not getting something close to this, suspect your motor.
What does a proper break in do? Basically, a new motor comes with flat
brushes and a round commutator. The idea is to wear the brushes down in
such a manner that you have a curved surface (and thus more contact area)
at the commutator/brush interface. If you try to break it in by simply
flying it at full load, you create a lot of arcing which pits the surfaces
and degrades performance.
Note that you must break in the motor prior to using it. If you've already
pitted the brushes and commutator, it is too late. You then have to settle
for what you have, or buy a new motor. You can expect this procedure to
improve power output 10-30 %. In the case of my Goldberg Electra, I
actually had to increase the down and right thrust angles of the motor to
keep the airplane from making a hard climbing left turn under power. Using
a broken in motor made a VERY noticable difference.
This procedure has been shamelessly stolen from the Hobby Lobby catalog.
If you don't already have a copy, it's worth getting as it contains a
goldmine of information on electric flying.
Ideally you'd like to run the motor at about 1/3-1/2 it's rated voltage
with no load (without prop) for an hour or two. Long enough to wear the
brushes down without arcing. The R/C car guys have special transformers
for this, but all you really need for a typical 05 can motor is 2 alkaline
D cell batteries and some spare 12 guage wire. Simply hook the batteries
up in
series so you have a 3 volt power source and hook the wires to the
appropriate terminals on the motor. Let the motor run until the batteries
are dead, and presto...you have a broken in motor.
If you have an old electric train transformer and a voltmeter, you can
also dial in 3-4 volts with the transformer and save the cost of 2
batteries.
As a practical matter, I have found that if you tape the batteries and
motor to a yard stick (meter stick), it makes a convenient platform, and
you can make all the connections with electrical tape...no soldering.
This is a very easy procedure that will pay big dividends. If you have
further questions, feel free to drop me a note.
Terry Gamble
<a href="http://rcgroups.com/shared/nospam.php?u=terrantula&d=aol.com">terrantula(at)aol.com</a></pre>
</body>
</html>
<head>
<title>How To Break-In an 05 Can Motor</title>
</head>
<body bgcolor="#FFFFFF">
<pre>Important...Break in Your New Electric Motor
My experience with inexpensive 6-7 cells electric sailplanes has convinced
me that an important building step is properly breaking in the electric
motor. I have seen a few of these airplanes that give very lackluster
performance and one example of an airplane that took a fully charged pack
just to reach about 200 feet. The owners invariably conclude that electric
flight is impractical because the airplane is too heavy. This seems a
logical conclusion because their motor comes on when they push the
throttle stick just like it's supposed to. It doesn't occur to them that
the motor could be the problem.
These inexpensive ferrite motors are very inefficient at converting
electrical energy to thrust. Even a good one is pretty lame compared to a
more efficient cobalt motor. Therefore, we need all the power we can
squeeze out of them. The reason we bother with them at all is because they
are so inexpensive they are practically expendable. Properly set up, they
do an acceptable job of pulling our sailplanes to altitude, and the price
is very attractive to beginners. They are a good way of "testing the
waters" of electric flight without spending a fortune.
I have weighed a couple of these doggy airplanes, and found that they were
no heavier than mine. I have also used the owners battery pack to insure
that the problem isn't a weak battery. I was left to conclude that the
motor was the culprit, and several "experts", including Hobby Lobby back
this up.
A two meter electric sailplane typically weighs 50-55 oz. You should
expect to get 2 1/2 to 3 climbs to about 500 feet out of a typical 1400 ma
R/C car pack. Or, you can get about a dozen climbs to 100 feet, depending
on your preference. Interestingly, it doesn't matter very much whether you
use a 6 or 7 cell pack. The 7 cell pack makes the airplane climb faster,
but it doesn't seem to have much bearing on total altitude gain. If you're
not getting something close to this, suspect your motor.
What does a proper break in do? Basically, a new motor comes with flat
brushes and a round commutator. The idea is to wear the brushes down in
such a manner that you have a curved surface (and thus more contact area)
at the commutator/brush interface. If you try to break it in by simply
flying it at full load, you create a lot of arcing which pits the surfaces
and degrades performance.
Note that you must break in the motor prior to using it. If you've already
pitted the brushes and commutator, it is too late. You then have to settle
for what you have, or buy a new motor. You can expect this procedure to
improve power output 10-30 %. In the case of my Goldberg Electra, I
actually had to increase the down and right thrust angles of the motor to
keep the airplane from making a hard climbing left turn under power. Using
a broken in motor made a VERY noticable difference.
This procedure has been shamelessly stolen from the Hobby Lobby catalog.
If you don't already have a copy, it's worth getting as it contains a
goldmine of information on electric flying.
Ideally you'd like to run the motor at about 1/3-1/2 it's rated voltage
with no load (without prop) for an hour or two. Long enough to wear the
brushes down without arcing. The R/C car guys have special transformers
for this, but all you really need for a typical 05 can motor is 2 alkaline
D cell batteries and some spare 12 guage wire. Simply hook the batteries
up in
series so you have a 3 volt power source and hook the wires to the
appropriate terminals on the motor. Let the motor run until the batteries
are dead, and presto...you have a broken in motor.
If you have an old electric train transformer and a voltmeter, you can
also dial in 3-4 volts with the transformer and save the cost of 2
batteries.
As a practical matter, I have found that if you tape the batteries and
motor to a yard stick (meter stick), it makes a convenient platform, and
you can make all the connections with electrical tape...no soldering.
This is a very easy procedure that will pay big dividends. If you have
further questions, feel free to drop me a note.
Terry Gamble
<a href="http://rcgroups.com/shared/nospam.php?u=terrantula&d=aol.com">terrantula(at)aol.com</a></pre>
</body>
</html>