Dave decided to use battery storage
bags and ditch the metal box.
chamber? Blammo! It could make a bad
situation much worse.
Some pilots use metal ammunition
boxes with the lid latched and drill
a hole to let the cord pass through.
Imagine a battery fire with all of the
“products of combustion” trying to get
out through the little hole. How about
a rocket-powered box shooting around
the workshop? Cue the cartoon music!
There are several videos online
showing LiPo battery fires. Some are
deliberately staged for educational
purposes, and others were accidental,
caught on video by chance. What they
have in common is a great deal of smoke
and heat being suddenly released.
Often, there will be secondary
ignitions as other cells overheat and
ignite after things seem to have settled
down. The batteries commonly jump
around when they “pop,” and will fall off
of tables or bounce around a room. This
is an argument against merely setting the
pack on top of a charging bag or a heat-resistant surface. It needs to be contained
interesting clips show
these fires igniting
charge bags. The
bags puff out and
release the smoke,
but contain the
flames and heat.
offer these products,
optimized for our
use. Users confirm
that they do work.
In my opinion,
these special bags are the best answer
to storing, transporting, and charging
LiPo batteries, and I have switched to
this method. The double-walled steel
box I’ve been using is gone, and my
new fire-resistant bag is in use. Watch
some online videos and make your own
My request for information about
finishing old, half-built models brought
some great comments. Many builders
have successfully completed airplanes
that had sat around for long periods.
The consensus is that the wood and glue
joints need to be carefully inspected
because poor storage conditions can
have an effect.
One aeromodeler said, “The hardest
part was finding all the original parts that
had scattered over the years, and having
to replace parts that I had borrowed and
put into other planes.”
There doesn’t seem to be any type of
glue that holds up better than others.
The storage conditions and quality of the
original materials make all the difference.
More than one modeler reported that
multiple airplanes that had been stored
together aged differently.
The good people at AMA
Headquarters in Muncie, Indiana,
forwarded me an actual paper letter from
a reader. Better yet, it was handwritten,
just like in the olden days! Earl Wheelock
wrote it, and asked that I remind
everyone about a critical difference
between gas and electric power systems.
If a gas-powered propeller strikes
something, the engine usually stalls and
stops running. Electric motors are not
that way. The propeller will continue to
spin during and after the initial strike—
all the more reason to keep our hands
clear of the airscrew! Thanks for the tip,
Put a Ring on It
A related issue was raised by another
reader. He saw an E- 36 model with
a motor reportedly turning a 7-inch-
diameter propeller at 16,000 rpm. His
concern was that the propeller on this
model was held on by a prop-saver
device with a single rubber O-ring, such
as would be found on a low-powered
park flyer. Failure of the O-ring could
have serious results.
I’m no expert, but I agree that the
numbers seem to call for a different
type of propeller-retention system—one
better suited to high rpm. This situation
might not be specifically covered in the
rules, and it would be up to individual
contest directors to make a decision.
Please contact me and say why you
agree or disagree. As always, I’ll leave
your name out of it, if you prefer.
Lance Gets Lanced
Lance Novak gets to wrap things up
this month with a horrifying tale of
laceration and pain.
“I have a special protocol with my
hobby knife. I always lay it in a spot
where it can’t roll, with the blade facing
away. So one day I was working on MiG-
15 wiring and using the hobby knife,
dental tools, and hemostats, and I got
sloppy and set the knife down with the
blade facing me.
“Then, as I reached for another tool
(while looking the other way), my
forearm touched the point of the blade.
The handle jammed against something
firm and the blade was pushed all the
way into my forearm. The blade was in
so deep you couldn’t see it. Basic first
aid stopped the blood flow, but it looked
like I had been shot. It took several
weeks to fully heal.
“The moral of the story is to never lay
down a sharp tool pointing at you, and
look where you’re reaching.”
90 Model Aviation JUNE 2015 www.ModelAviation.com
SAFETY COMES FIRST