76 M ODEL AVIATION
Gary A. Shaw
S a f e t y C ome s F i r s t
Box 4520, Milton FL 32572; E-mail: [email protected]
SoMeTIMeS I find it difficult to pick subjects for my
column, because there are so many facets of our hobby that
are ripe for discussion.
Rather than pick up from where I left off in the last
column, this month I’ll dip into the E-mail and mailbag to see
what questions await.
One letter discussed things that can happen when you use
Dremel® tools.
A gentleman left his Dremel® hand tool on without
knowing it when he left his shop for the evening. He had
covered the tool with a rag, unaware that the shaft was turning
slightly.
Returning the next morning to the smell of smoke, he quickly
found the source and fixed the problem. The rag became tangled
in the shaft, and the unit jammed. It became so hot that the rag
started smoking and almost burst into flames. Definitely a
situation to avoid!
How do you prevent this? Unplug all electrical items when
you leave the shop, and install a smoke alarm. Contact
your local fire or police department if you need
assistance; many have programs that provide
smoke alarms free of charge.
Another letter described how a modeler’s
Dremel® cutting disc fell apart while moving at a
high rpm. The modeler was not wearing eye protection.
He wasn’t injured, but his son wasn’t as fortunate—a piece of
the disc hit his ear, causing a skin puncture and slight bleeding.
The modeler and his son were lucky that their eyes weren’t
involved, but prevention would have almost eliminated the
threat. Wearing eye protection, and keeping the inquisitive
father away when using high-speed tools, would have made this
story a nonevent.
Many would argue that cutting discs couldn’t possibly carry
the momentum to do much damage.
Although I’m not going to get into the math of weight and
velocity, it’s best to err on the side of caution and wear
protective eyewear whenever possible. It’s a very cheap, safe,
and simple method to ensure keeping precious eyesight.
One modeler wrote to warn about unplugging tools when
you’re done with them. He indicated that he routinely uses
his wood-burning tools to engrave his name inside his
airplanes. On one occasion he left the tool on overnight,
which started a small fire in his garage. Fortunately for
his family, he had a smoke detector in the garage that
went off during the night, alerting them to the crisis.
There’s an investment that paid for itself in spades! I’m
told he is now meticulous about unplugging tools when he
leaves the shop!
You Might Be Surprised: If you’ve flown many hours at all,
you’ve probably experienced a loss of control at some point.
You search for solutions each time this happens, but often
overlook the obvious.
The next time you’re at the field, turn on your airplane, then
your transmitter.
Why in this order? Because if you see surface movements on the
airplane before turning the transmitter on, it might mean someone is
on the frequency for which you had the pin.
With the antenna fully down, walk away from the airplane as
though you are doing a radio check. Move all the controls
around to ensure that everything works well. Keep walking until
control is lost.
At that distance, turn and face the airplane. Point the antenna
directly at the airplane and wiggle the sticks. Continue moving
the sticks as you slowly move the antenna toward the sky.
You should be able to observe that control gets better as the
tip of the antenna moves away from the model. The antenna
transmits best from the side—not the tip.
Imagine the model in flight. If the transmitted signal or
reception is weak for any reason (low batteries, short receiver
antenna, another signal, etc.) and you point the antenna
directly at the model as it flies, you can
lose control!
If you have a transmitter with
adjustable antenna angle, orient it so it
points away from the model as you fly.
Most modelers fly with the transmitter
pointing at the airplane; adjusting the angle
up 10-20° is all you need.
Propeller Safety (Metal Versus Plastic,
Fiber, and Wood): The September 2000
column focused on why AMA outlawed
the use of metal propellers.
I’ve received a large portion of mail
expressing concern about the cutting and
shearing ability of plastic, fiber, wood,
and metal propellers.
Robert Angel of Santa Maria CA
expresses a strong opinion.
“Mr. Brandon is right on the money
when he questions the safety of plastic and
carbon propellers over wooden ones. There
are good reasons why the heavier, sharper,
unbreakable plastics do more damage to
flesh, tendons, bone, and inanimate objects
than their wooden counterparts.
“Here’s why a plastic propeller does
more damage.
“After weighing several samples, I
found that plastic propellers weigh about
1.9 times, or nearly double, the weight
of [wooden propellers] of the same
diameter and pitch. If weight
distribution between hub and tip is
similar, then a plastic propeller has
about 1.9 times, or nearly twice, the
momentum (destructive power) as the
wood propeller.
“Plastics are stronger and will deliver
full momentum. They don’t shear off as
wooden propellers usually do. When a
plastic propeller stays intact on impact, it
delivers not only the momentum of its
own mass, but that of all the
reciprocating and rotating metal inside
the engine.
“Some folks are concerned about
wooden propellers coming apart at high
speed and/or shearing at impact. I’ve
flown models for more than four years,
and I’ve seen a lot of propeller
incidents, and even been involved in a
few. I’ve had a couple of plastic
propellers separate near the hub at high
rpm, but never a sound wooden
propeller. When a wood blade shears on
impact, the sheared portion usually falls
away harmlessly and contains relatively
little destructive energy.
“Few engines turn faster than those of
Formula I [Pylon] racing, where safety is of
paramount concern. These Contest Directors
are generally sharp on technical matters and
allow only wooden propellers. No doubt for
the same reason discussed here.
“The propeller always follows the laws
of physics, not the logic of an unbeliever in
the way it’s going to strike and do damage.
Follow the laws of physics whether you
believe in them or not. Unfortunately,
human nature resists the simple remedy of
banning the various plastic and carbontype
propellers.
“A good starting point would be to
encourage the wooden propeller-makers
to bring back higher quality, in the
shape and finish of wooden propellers.”
Loctite®: A common safety practice
that many modelers overlook is
securing metal-to-metal screw
connections with Loctite®, to ensure
that screws stay intact during flight.
Vibration plays a large part in what
backs apart and comes off during flying.
One drop of nonpermanent Loctite®
goes a long way toward ensuring you the
kind of security your model needs to
take to the air.
Consider using Loctite® on wheel
collars, quick clips where pushrods are
used, and screw links.
Do not use Loctite® on anything
that becomes hot. It’s almost
impossible to get pieces apart once
they’re heated up.
That’s all for this month. Hope your
holidays are pleasant and the gifts are
great! MA
