Frequently Asked Questions-2011/09

PLEASE WRITE
in with your
questions; that is
the only way we
can keep this
column format
going. When
referring to already
published questions
and answers (for
follow-ups), always
provide the number
as a reference.
Also note that
references to
addresses and
websites are placed
in a group, separate from the text, at the end
of this column under “Sources.” A “Tips”
feature is provided in addition to frequently
asked questions; these hints are numbered
in the same sequence as the questions and
answers.
Q-514: AMA member, Al Schmidt, asked,
“Where can I purchase the small circlips
that are used on the shafts of our brushless
outrunner motors?”
A-514: This was a basic and simple
question, but read on carefully because
there is much to learn from this answer. A
circlip is actually a retaining washer.
Most modelers would be more familiar
with the “E”-shaped retaining washer.
These washers are common and are pressed
into position using ordinary pliers.
As many have discovered, installing
these “E” washers can be a problem,
especially if it flies across your shop and is
lost forever. A circlip’s shape is similar to
that of an “E” washer, with one exception:
there are two holes at each end of the “C”-
shaped washer.
I’ve included a photo of both retaining
washers in this column so you can
understand to what I’m referring.
What makes the circlip unique is that
those two holes accept the tip of a special
pair of pliers. Attach these pliers to the two
holes and as you squeeze the pliers, the
circlip will expand, allowing it to be easily
installed on a motor shaft (or for many other
applications).
Because the circlip is attached to the
pliers, it won’t “fly” away from you. Because
of this feature, many modelers have
abandoned the “E”-shaped retaining washers
and gone to circlips.
One of the best sources for circlips is
McMasters-Carr. I’ve listed the company’s
website in the “Sources” section. I have
included sources for the circlip washers as
82 MODEL AVIATION
well as the special
pliers.
Al Schmidt
ordered his washers
and pliers and was
happy with the fast
service. He
explained how he
replaces worn-out
bearings on his
brushless outrunner
motors. Al’s
techniques seem
simple.
He found that the
Boca Bearing
Company can supply
a variety of tiny ball
bearings that fit most
of our brushless
outrunner motors. I’ve listed contact
information for Boca Bearing in the
“Sources” section. With Al’s permission, I
have also included his personal email address.
Al indicated he would be happy to
describe his motor-rebuilding process to any
reader who might be interested. Thank you,
Al, for making that offer.
Circlip retainer applications are not limited
to electric motors. Many of the carburetors on
our fueled engines employ this type of
retainer, so keep that in mind.
Q-515: “I’d like to get the most out of my
new computer-controlled RC transmitter but
I’m having a tough time understanding the
detailed manual that came with it. Are there
any books that take you through the basics,
without requiring a degree in electrical
engineering?”
A-515: There are probably many such books
available. They tend to change throughout the
years as new technology comes available. It is
smart to buy a new book on the subject every
few years.
Circlip retainer washers
Bob Aberle | baberle@? Frequently Asked Questions optonline.net
Also included in this column:
• Radio Programming Essentials
• Twin electric motor problem
• Follow-up to aircraft storage
racks
• Cosford large-model aircraft
show
• Carbon-fiber pultrusions
One book that I discovered recently was
written by the editors of Model Airplane
News, which is published by Air Age Inc.
The 30-page reference book is titled Radio
Programming Essentials.
It is available in printed or digital format
for $17.95 plus postage. The book describes
the main transmitter screen and graphic
displays. Then it gets into the system menu,
which includes model type and model
name, switches, knobs and buttons, wing
type, and tail selection.
Then it delves deeper into the functional
menu, which includes exponential and dualrate
controls, servo travel, reversing, and
trims/subtrims. Finally the book describes
program mixing such as V-tail and elevons,
aileron differential, and rudder-to-elevator
mixes.
Above: Al Sc h m idt
d i s a s s e mb led t h i s
ty pic a l b r ush l e s s
outrunner motor to
in s t a ll a n e w ba l l
b e a r i ng on th e
motor shaft.
Al inserted the special pliers into the two
hole s of t h e tiny ci r cl ip. Squeez ing t h e
pliers expands the circlip, making it easy to
slip it onto the motor shaft.
Th e circl ip m entioned i n the text is pictured at the t op. At the
bottom is the “E”-type retainer washer. Jerry Smith photo.
09sig3.QXD_00MSTRPG.QXD 7/22/11 10:47 AM Page 82
and ESC the same brand/model type?
Second, were they bought at the same time?
Third, is it always the same motor that starts
late? Fourth, try swapping ESCs and see if
the problem moves with the ESC or it stays
with the motor.”
I think you can get the idea as to where
this is going. If after following these
questions and making any substitutions, you
still have that start-up problem, you may
have to live with it. But swapping in a
different motor and/or ESC of the same
brand and type might correct the situation.
This isn’t a definite answer, but hopefully it
will get you into the ballpark.
Follow-up to Q-474 that appeared in the
December 2010 Model Aviation: In that
issue, a reader showed an interesting aircraft
storage rack made from PVC tubing and Tee
connectors. The problem is that I didn’t
mention that the Tee connectors were a
special kind and not the same as the morecommon
variety that you might find at
Home Deport or ACE Hardware stores.
The kind of Tee connector you want
snaps onto the support tubing. The photo
should illustrate the story. After snapping
the Tee to the support pole you just slide it
into position to accommodate your
particular size aircraft.
Along these same lines, another reader
showed how he makes up storage racks to
support his aircraft while being transported
in his van or SUV. I’ve included a photo of
that idea. In this instance, the suggestion
was to use adjustable shelf brackets and
standards. It’s a different approach, but
interesting!
Tip 515: I couldn’t resist mentioning this
YouTube presentation of the Cosford 2007
large model aircraft show in the United
Kingdom. We are familiar with our large
aircraft shows throughout the US. This
video provides a perspective from another
country.
The site is listed in the “Sources” section.
I thank Frank Korman for providing this
reference. After viewing this YouTube video
you might also want to visit the Large
Model Association’s website.
TIP-516: AMA member, Frank Pisano,
offered this suggestion after reading a
construction article that I had published. The
airplane was made from sheet foam. I had
suggested that a carbon tube, much like an
arrow shaft, be placed on the bottom of the
wing at mid-chord as a form of
reinforcement.
Frank had a better idea. He uses a DPP
carbon-fiber pultrusion strip that he obtained
Car bon-fibe r p u ltrus ions, obtained f rom
t h e A2Z Co r p. , c an rei nfo r ce vari ou s
a i r c r a f t s t r uc t ur a l s u rfa c e s . Th i s i s
especially helpful on sheet foam.
An e xcellent ref erence sourc e, Air Age’s Radio Programming Ess enti als e xpla ins ho w to
make the best out of your com put er- co ntr olle d RC transmitt er.
The book uses a Horizon Hobby
Spektrum DX8 transmitter in all the
photographs, but you will find it applicable
to most other system brands. The Air Age
website is listed in the “Sources” section.
Q-517: “I have an electric-powered twin
aircraft. In other words it has two motors.
Why does it take two or three tries to get the
motors to start together? It’s random; one
will start normally while the other
struggles.”
A-517: I thought I might pick Tom Hunt’s
brain on this answer since he is one of the
foremost electric power experts in the
country. Tom came up with a checklist of
questions, the answer to any of which might
point out what is causing your motor startup
problem.
Tom asks, “First, are both your motors
Th e PVC T ee will s nap on t o a len gth of
PVC pipe o r t ubing. Th is Tee w orks well
for the aircraft s torage r ack descri bed in
FAQ-474.
An alternate aircraft storage rack can be
made from common shelf brackets and
standards to transport your aircraft in a
van or SUV. You can adjust the spacing of
the brackets.
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