Safety Comes First - 2008/08

116 MODEL AVIATION
LOOK AT THE two photos of Don Butman’s immaculate P-40. This
was a Guillow’s kit, mind you. He is almost finished building it, with
only the propeller installation to go.
The whole model comes apart easily for storage or crashing, and it
is held together with imbedded magnets. Even the CO2 motor is held in
place magnetically.
Don has been using rare earth magnets in many of his models
lately. They are now available in many sizes and are very powerful.
Small ones are strong enough to hold a wing or light-duty motor
mount. This means no more latches or exposed rubber bands.
This particular model is in the safety column because of the
unusual problem Don had with the magnets that hold the wing in
place. They held
with great force
when he installed
them—so much so
that he put a layer
of covering over
them to increase the
distance a bit
When the ironon
material was in
place, Don was
surprised to find
that the magnets
were holding with
much less force
than before. He cut
the magnet faces
clear, and there was
still so little
attraction that he
added a wing peg for security.
I’ve gotten into the habit of using these little magnets in my
models, despite the fact that I can’t build ’em as pretty as Don can. I
never use iron-on covering and I’ve never had a problem with
weakening hold.
My suspicion is that the hot iron was the culprit. I know that high
temperature can demagnetize a magnet, and that is exactly what these
were exposed to.
Perhaps there is something else going on, but this story is presented
as a warning to those who use rare earth magnets, in actuators or to
hold models together, and iron-on covering. Watch the temperature or
install the magnets after the covering to keep things clinging as they
should.
Safety Comes First Dave Gee | [email protected]
The sudden attraction to magnets: a heated positive-and-negative debate
Also included in this column:
• Flags on 2.4 GHz
transmitters?
• Model outsmarts tie-down
and attacks pilot
• Solar-powered field house
• Dave rants about Internet
etiquette
Don achieved nice results with his Guillow’s P-40 kit!
The FF model has CO2 power.
San Fernando Valley RC Flyers club members charge their electric
models using solar energy. This is how they built the system.
California builder Don Butman’s P-40 is held together with rare earth
magnets and comes apart for storage and/or abrupt arrivals.
BR McLean and I corresponded about the issue of frequency boards
and impounds as related to “old fashioned” radios that require
controlled channels and newfangled systems that are not subject to
interference. There are some differences in opinion on the subject. He
had an interesting suggestion and I promised I would mention it, so
here goes.
The problem is that a new or absentminded flier can get confused
about which radios can and cannot shoot down other models and
possibly turn on an older system by mistake—
crash! Other pilots are frustrated by fields that
keep spread spectrum systems under some
sort of frequency-control policy in this time of
transition.
Mr. McLean suggested using special
identification flags on 2.4 GHz transmitters
that identify them as not requiring a frequency
pin. He showed me a ribbon that read
“Spectrum Radio” and can be attached to the
stub antenna.
People have had different reactions to this
concept. What do you think? Write to me via
postal mail or send E-mail to the address in
the column header. I’d like to hear about your
close calls too. They make great reading and
save others from harm.
I have a story about an RC pilot who shall
remain anonymous, although you might be
able to recognize him by his bandages. I
received a forwarded message that read:
“While working on the engine for my
Aeromaster last Sunday I tried to stop the
propeller with my right hand. I broke two
fingers and my thumb. My thumb required a
skin graft because so much was removed by
the propeller. I must have 100 stitches in my
index finger alone.
“I had the plane tied off like I always do.
When it first started it was held back just fine.
When I killed the engine, the plane rolled
backwards about 5-7 inches down a small
incline. I did not notice this and must have
moved closer to it to restart the engine. Well it
jumped forward and startled me, so rather
than falling backwards I reached forward.
Good thing it was a wood blade and not
carbon fiber otherwise I am sure I would have
lost my thumb and index finger.
“Lesson learned? Always pull the plane
against the restraint prior to starting. Share
this with anyone you want. Maybe a reminder
of the dangers will be good for us all.”
118 MODEL AVIATION
I have the following comments by Don
Lowe about this incident.
“People get hurt all the time because of the
lack of secure restraint on starting or
inattention to where the propeller is. Guys
unthinkingly reach through a whirling prop to
reach the mixture control, etc. All we can do
is bring these dangers to their attention from
time to time.
“A lash restraint such as the one in this
report is the least desirable because of the
probability of an occurrence such as this.
Have a buddy hold it for you or block it in a
fashion that prevents motion fore or aft.
“I have seen guys start without restraint at
all counting on their quick reaction on the
throttle, and I have seen guys severely slashed
and rushed to emergency because of this. That
propeller is dangerous—even those on electric
models.”
Don has many years of experience, and his
take on this is exactly right. Use a helper or a
starting structure when available. If you have
to use a tie-down, remember this story and
don’t let it happen to you!
Awhile back I printed a photo of a solar
charger that the Los Angeles-area San
Fernando Valley RC Flyers club built into its
field house. The setup has panels on the roof
that charge storage batteries that, in turn, can
recharge flight packs on models.
These modelers even built a neat shelf to
hold the batteries out in the open while the
juice flows. Many pilots can use the system
simultaneously.
I got many requests for details about this
environmentally friendly setup. The club
members have kindly furnished a drawing of
how they laid out the components. It is not a
full schematic. You will need some electrical
know-how to build your own rig, but the parts
are readily available.
I understand that the club members have
expanded the system to charge even more
airplanes and to power a grinder in their
workshop—all without paying a dime to the
electric company.
Off-Topic Rant: Strap yourselves in. I have a
point to make, but I’m taking the long way
’round.
I recently visited Boston (to promote our
hobby for the AMA) and was thrilled and
humbled to visit places where men conceived
and fought for the rights that we enjoy today.
Take freedom of speech, for example. We can
write and publish whatever we please (at least
I can until the day MA Editor Michael
Ramsey finally reads my column), for good or
ill.
The Internet is the ultimate expression of
this liberty, and thousands of AMA members
communicate at the speed of light using chat
rooms and online bulletin boards. I get lots of
column material from friends I’ve never
actually met, along with jokes, advice, and
spam ads for miracle creams.
However, certain problems arise when we
have unfettered, anonymous electronic
freedom of speech. Human nature tends to
drag uncensored chat rooms down a muddy
path of off-topic insult messages that make
political campaigns look like pillow fights.
We modelers are not immune to this. The
very nature of our hobby tends to make us
arrogant, since aeromodelers are in total
command of every aspect of their personal
fleets of flying machines.
I lurk and post on a couple of popular
message boards. Sometimes it’s hard to
follow a topic thread through all the sourpuss
“flame” messages. I recently saw a post that
asked what a Web site visitor might think of
modelers after reading a string of rude
messages.
A common feature of such posts is to gripe
about some issue by a blaming club or AMA
leadership. No solutions, no discussion, no
ideas, just some vitriol and name-calling.
Some of the E-mail I get is like that, and I
don’t even know how to respond.
Thankfully, most messages are from MA
readers who have given some thought to a
problem and have a bright idea or insight to
share. Some of these messages end up here in
print, and some others are brought up at AMA
meetings or are otherwise used to improve our
hobby.
I’m just an AMA volunteer, but I pay
attention to the opinions of somebody I see
helping out at some flying event. An
anonymous message insulting some official or
department? Not so much!
This all comes up because of some
business I saw conducted at the AMA Safety
Committee meeting. Decisions were made
based in part on information and opinions that
came through E-mail messages and online
posts. AMA members who didn’t even know
about the meeting ended up greatly affecting
things and helped make the correct choices.
Guess which kind of E-mail and posts did not
play a part?
If you want to change things for the better,
there are ways to do it and ways to waste your
time. The AMA staff has put out a call for
members who want to play a more active part
in the advancement of the organization and of
aeromodeling. Take them up on it! MA
Sources:
Dave Gee
Box 7081
Van Nuys CA 91409