Safety Comes First - 2011/01

84 MODEL AVIATION
THE FOLLOWING is an e-mail
that was received by an AMA
member who is a recognized
helicopter expert.
“I’m a member of AMA and I
am interested in acquiring an RC
helicopter or build one. I would
like to ask a few questions and see
if you can help me?
“1. Is there a supplier of an
autopilot with a possibility to
insert or program a route with
waypoints for specific route?
“2. If I decide to build a helo
on my own using an electric tail
rotor motor, do you know of a
motor with 6 HP 17000 RPM?
“3. Where can I find a giant
RC helicopter—say over 5 feet in
length—for sophisticated flying
and night flying? And which
helicopter has giant rotor disc
diameter?
“4. What radio shall [I] use?
2.4 GHz, 5.8 GHz or 72 MHz?
“5. Can JR 11X be used for
autopiloting?”
What would you make of this?
The expert wondered if it could be
for real or if it was a joke. Or
maybe he was in contact with the
dumbest terrorist on the planet.
The expert sent a careful
response asking, “What purpose
would you be using this helicopter
for?” The reply was “Hobby and
maybe imaging.”
Time out! Our models are
sanctioned for hobby/scientific/
competition/
recreational use. If
we want to fly
commercially, there
is a different set of
rules.
Taking a photo
of your house from
an RC glider is great
fun. If a real estate
agent hires you to
photograph property
for a client, you are
no longer a hobbyist
and should comply
with local and
federal laws
regarding unmanned
commercial aircraft.
Back to the story
in progress, a bit of
Internet research
Dave Gee | Safety Comes First [email protected]
When things look suspicious, let the proper authorities take over
Also included in this column:
• Propeller nuts: loose bad, tight
good
• Kids in the pits can be the pits
• Drilled hub leads to a propeller
blade freefall
• Winch line becomes a cheese
cutter
Altering a propeller hub is a gamble. This model lost the bet when
a blade crashed through the fuselage.
RC glider flying is usually quiet and peaceful, but
Michael Morjoseph got tangled in a winch retrieval
line and showed that silent fliers can holler too.
A momentary distraction in the pits resulted in a
long, painful treatment and recovery for this pilot.
Watch those propellers! was inconclusive. The person was indeed a
new AMA member. He had a vague
company Web site, which could have been
set up in an hour by any 12-year-old.
He was probably legitimate, right? What
are the odds?
Time was up, and the helicopter expert
knew he had to report the e-mail exchange to
the proper government authorities and to the
AMA. Somehow the word even got to me.
What would you have done? Many AMA
members have had concerns about whether
or not our harmless, fun models could be
used to deliberately cause harm.
The Nazis had an autonomous unmanned
aerial vehicle called the V-1 Buzz Bomb
that carried a 1,000-pound warhead to a
predetermined spot, usually a city away
from the combat zone. Our models are tiny
in comparison, but they could deliver some
small but dangerous payload into a reservoir
or crash onto a busy freeway interchange.
The current availability of autonomous
flight systems is a worry to the authorities,
and the AMA is working to develop policies
so that we can have fun using these rigs but
remain safe from a national security
standpoint. Model aircraft have provided
enjoyment and education to millions of
people throughout the years. It’s a shame
that some might want to misuse our hobby
for such low purposes.
There are people in the world who want
to plan and execute murderous acts against
others. Given the situation, we hobbyists
need to be vigilant. We are not expected to
judge real modelers from evildoers, but
when things look suspicious it is time to let
the proper authorities take over.
I am not a proper authority on national
security. But I handle the safety column, so
01sig3.QXD_00MSTRPG.QXD 11/22/10 8:08 AM Page 84
if you want to see something here you
should e-mail or write to me.
I offer a choice of anonymity or fame.
When Chris Hyden generously shared his
story, he told me he prefers fame.
Chris wrote:
“I just got started in flying. Last week I
went to the field to maiden my glow trainer.
No one was there except my dad who
doesn’t fly.
“I got everything ready and started the
engine fine and put it up to full throttle
while it was on a test stand to warm up,
when all of the sudden my 10 x 6 prop and
spinner flew off the engine and started
spinning toward me. I wasn’t able to get out
of the way in time.
“The prop just ripped my pants and cut
my knee. (I had forgotten to dull the prop.) I
found out later that the nut wasn’t on tight
enough.”
Later? Chris found out at that moment
that the propeller nut wasn’t tight enough!
It’s hard to pick just one “most important
part” on our complex machines, but the
propeller nut is a contender.
Race car crews call it “wrenching” the
car: going over every nut and bolt to check
tightness. We do (or should do) a preflight
inspection as full-scale pilots do, but it is
easy to get complacent!
When the aircraft is safely in a test rig,
what could go wrong? Plenty! Just ask
Chris.
It’s nice to have some protection from a
runaway propeller, and Tom Gatchell wrote
to me about the pilot-station fences at his
local field. PVC pipe and orange snowfence-
type barricades are often used to
protect pilots. He wondered why we don’t
see metal posts and chain-link fencing more
often.
We discussed the cost factor, the
possibility that local permits might be
required for such “permanent” structures,
and how the plastic type would reliably stop
nearly all models. Even chain-link fencing
isn’t 100% accident-proof.
I told Tom that I would ask the audience,
since there are readers with tremendous
wisdom and experience. Have you tried
different types of fencing for pilot-pad
barriers at your field? Is there some reason
why metal is not used more often?
It has been said that touching a
transmitter antenna to such a fence can
cause range problems, but the new 2.4 GHz
radios don’t have long aerials. Please
enlighten Tom and me.
I generally don’t print gory photos, because
some readers might share my delicate
nature, but there are some doozies this
month!
The stitched-up hand belongs to a man
who asked to remain nameless. He took full
responsibility for putting his hand into a
spinning propeller, noting that “3 blades
take 33% more bites,” but he wanted me to
discuss a contributing factor in his incident.
A fellow flier at his field is known for
bringing small children with him and then
letting them run and chase through the pit
area. Apparently one of the tykes stepped
close to a model’s running engine and
distracted the pilot, leading to the injury you
see in one of the pictures.
Little kids “playing” in an RC pit area?
Bad idea!
I wrote about this topic awhile back and
am of the opinion that if small children are
taken into an active pit or flight area, they
should be held firmly by the hand or carried
at all times. The same goes for pets.
Any creature that does not know enough
to avoid hazards (and there are plenty at an
RC field) should be closely supervised by
adults for their own protection and the
protection of others. No excuses! You are
not doing your kids a favor by endangering
them in this way.
There may be a few very young fliers
who are an exception to this rule. On the
other hand, I have met adults who needed
their hands held.
If there is a local club in charge of the
site, proper steps should be taken to correct
such a dangerous situation. Child
endangerment is a criminal matter. Either
way, hurt feelings are better than hurt
bodies.
John Lane wrote to me about a propellerfailure
incident that luckily damaged only a
model.
“The plane has two 30cc gas motors with
4-bolt hubs. The owner/pilot wanted to use a
3-bladed prop both for appearance and
performance reasons. He drilled the hubs to fit
and brought it all to the field for a test flight.
“After a careful run-up, everything
seemed okay so he took off. On the second
circuit we heard a loud noise as the prop
shed a blade into the fuselage. He landed
with an engine hanging by the fuel line.”
Model airplane propellers take
tremendous stress—much more than you
might think. Running it on the ground is
nothing! Imagine the forces on the blades as
they transmit power during aerobatics or
throttle changes.
Propellers are designed with careful
stress analysis and years of experience. We
should think twice before altering one!
(Editor’s note: Even Laddie Mikulasko,
in his cool Turbo DC-3 article on page 18,
doesn’t recommend altering these model
components, and he shows his model with
homemade five-blade propellers! It’s not
worth the risk.)
In this case, the new holes removed
stock from the hub and weakened the
propeller enough to cause failure. Few
modelers have the equipment and knowhow
to properly test such a modification.
John did us all a favor with his reminder
of this basic engineering principle.
The RC glider fliers are seldom mentioned
in this column, since their quiet aircraft lack
propellers and are statistically safer than
most types of models. Michael Morjoseph
beat the odds, but not in a good way. He
kindly shared a photo of what can happen
when a winch retriever line gets tangled
around your leg.
I’ve seen how carefully glider crews
handle these systems, but somehow there
was a misunderstanding at the field that day.
In the instant before the winch was shut
down, Michael was badly cut.
Those tow rigs can be very powerful,
and it is easy to see why the pilots treat
them with such care. MA
86 MODEL AVIATION
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