68 M ODEL AVIATION
DrEAM AIrpLANE Technology: It’s a wonderful
thing to behold when you get the chance to sit
in the seat of an Airbus 300.
What fascinated me most was the
lack of a front-column yoke
system, traditional in most modern
aircraft. A small control arm under
the side windows, similar to a
computer-game joystick (fly-by-wire
technology), replaces the yoke system.
I was invited to occupy the captain’s seat for a
bird’s-eye view after I was caught staring into the
airplane’s cockpit. You should have heard the air
whoosh behind me as I jumped into the seat!
What spectacular technology! Conventional
instrumentation has been replaced with cathode-ray
tube displays, talking computerized
flight systems, autopilots that can
take off and land the airplane, etc.
I commented to the pilot that RC
(Radio Control) flying could use
such technological wizardry, but
made the point that it is slowly
getting there. He indicated that he
did fly RC, and he pointed out the
similarities that exist between
aircraft systems and RC flight.
The captain watched me move the
side-stick control (a couple inches left
and right), and commented that the
amount of input I made would move
the aircraft in a violent maneuver (roll
it over). He explained that sensitivity
was controllable, and was set so only
slight movement provided the control
needed (like computer radios).
The aircraft also has auto
throttles, and the ability to take off
and land itself.
What we wouldn’t give for
technology like that! RC modeling
is almost there—all it takes is cash
and setup know-how.
The pilot talked at length
about safety and the redundant
systems that back each other up,
but all I could really think about
was how much it would cost to
build a Scale RC Airbus with just
a few of the bells and whistles he
was mentioning! More than I could afford, but wouldn’t
it be a safe and fun airplane to fly?
From the Mailbag: In recent columns I’ve written about problems
I’ve had with collapsible antennas coming unscrewed from the
transmitter base, appropriate cleaning, and signal-strength problems
related to not fully extending the antenna.
I mentioned I had begun using “rubber ducky” (or shortmounted)
antennas to eliminate extension problems and cleaning
requirements. I’ve received numerous letters as a result, with points
I’d like to share.
Mal Richards (Whangarei, New Zealand) describes
problems he encountered from a worn telescoping antenna.
“The December issue of Model Aviation had a
bit about a modeler with antenna problems. You
may be interested in my experience. I have
owned a Futaba 9VA for 13 years, but I do
not consider that it has been used a lot, as
it is not the only radio I use.
“I was flying a Scale Aeronca LB when
I had increasing control problems—until I
had no control. The resulting smash was very
painful. I checked everything, and thought I
had found the problem to be a faulty battery.
“I next used the radio in a .90-powered
aerobatic model, and got the top aerobatic flier
in the country to test-fly for me. All
looked well on takeoff, then half a lap
later I had no control—another crash.
“I sent the radio away to the national
agent for checking and got it back (with
a bill), reporting that all was well. Next
time I flew, after range-checking of
course, all seemed well until the model
got a bit further away and I again had a
radio problem. I managed to get the
model back, and range-checking again
showed I had a problem.
“I was advised to take the radio to
a local electronics expert, who said
that I would not get it back until it
was fixed! When he called me to say
the radio was fixed, he said that the
main problem had been that the pullout
transmitter antenna was worn
where it clipped into place when the
aerial was pulled out, and it
sometimes did not make contact.
“After repair, he [the expert] had a
range of 150 meters aerial down, with
the receiver inside a building. It does
appear that the usual range check at
some 25 to 30 meters is insufficient
with some transmitters—you should go
at least 100 meters with aerial down.
“As an aside, with clip-in Ni-Cds the
saying in our club is: ‘It is not if you will
crash, but when.’ It will happen if your
batteries are not plugged in.”
Mal didn’t indicate what the antenna fix was, but in most cases
an easier solution is to replace it when a problem is found.
Antennas are cheap compared to the loss of an aircraft.
Thanks for sharing the results of your findings, Mal!
Jim Petro sent an E-mail about a problem he’s encountered with
rubber duckies.
“I understand that you have replaced a telescoping transmitter
antenna with a ‘short, flexible unit,’ which I infer to be a ‘rubber
ducky’ antenna. I also did this several years ago, but the loss of three
airplanes in one year recently made me switch back.
Gary A. Shaw
Safety Comes First
Box 4520, Milton FL 32572; E-mail: [email protected]
March 2001 69
“The key to the problem came as I
was trying to make the first flight of
the beautiful Stingray Slope Glider for
my review in Sailplane & Electric
Modeler magazine. The rubber ducky
seemed to be a great idea, and I put
two on my radios. I was 100% satisfied
for two years.
“Then I realized it was causing
carelessness when [I was] using a
standard radio and forgetting to extend
the telescoping antenna. The worst came
in the third year when three airplanes
suffered sudden servo drive to the end of
travel and locked. The common
denominator was that a rubber ducky
was in use each time.
“Luckily, the carbon fuselage on the
Stingray was causing antenna location
problems that needed fixing. Small
glitching was still occurring. Inspiration
said that the antenna was the only part I
hadn’t checked, so I borrowed a
telescoping antenna and replaced the
rubber ducky. No more glitches and all
successful flights!
“I checked the other rubber duckyequipped
transmitter and found the same
history and current conditions. A
replacement telescoping antenna cured it
also. I cut open the rubber ducky skin,
and found absolutely no damage or hints
of failure. It seems that the rubber ducky
electronic characteristics are finally
tuned with a small sweet spot.
“After two years, the AM [Amplitude
Modulation] and FM [Frequency
Modulation] radios drifted off the sweet
spot. Both radios are used on several
Electric and Slope Glider models, and
since the switch a year ago there are no
more losses because of what comes from
the transmitter—only from the input
thumbs.
“I miss my rubber duckies.”
Jim’s point was noted; my radios are
making a trip to the dealer for a checkup,
although I’ve used a rubber ducky
antenna for several seasons with no
trouble.
Better safe than sorry, as the saying
goes!
I also wrote that I used WD-40™ to
clean my telescoping antenna, but readers
told me I was nuts and that I needed to use
rubbing alcohol. More mail arrived,
stating acetone was the best, etc.
Now I use a can of electrical contact
cleaner purchased at Radio Shack®, and I
haven’t had any issues since.
If you are using WD-40™, read the
following from Archie Caldwell (Grass
Valley CA).
“I just read about your problem with
WD-40™ in the December 2000 Model
Aviation. Someone should put the word out
that this stuff is a ‘solvent,’ not a substitute
for any lubricant or cleaner.
“When WD-40™ comes in contact
with most electrical components, it will
kill them without hesitation. I have a
friend who repairs auto tape-decks,
players, etc. If he even smells WD-40™,
he recommends replacement because
these are not easily repaired.
“I used to work for a gun dealer, and
we saw many fine firearms almost ruined
and gummed up from having it sprayed on
and left for a period of time.
“You know that it is wise not to use it
where a fine lubricant is needed. It might help
you undo rusty bolts and nuts; however, I
have tossed any can I had into the trash.”
I still have my can, but I won’t use it on
electronic parts anymore—I hope you
won’t either.
that’s it for this month. Here’s wishing
you fun winter building and soft ski
landings (where intended, of course)!
Until next month … MA
