Frequently Asked Questions-2013/04

These four types of rubber bands are commonly used in our hobby.
Scalelike wing struts loosely  t into
slots that are cut into these plywood
inserts. This type of strut is used on
Scale aircra strictly for appearance.
At the fuselage end, the wing
struts are attached with sheetmetal
screws that go into
hardwood blocks. The strut is
attached here, but not at the
wing end.
Tips for holding wings down with
rubber bands
Q568: Do you know of any criteria for
determining the size of rubber bands
needed to hold a wing in place? I have a
32-inch wingspan airplane with a 91/2-
inch chord. The plans say to use two
No. 32 rubber bands on each side. Since
the No. 32 rubber band is 31/2 inches in
length, that’s quite a stretch!
A568: I like to use three rubber bands
on each side (a total of six). In general,
a rubber band can stretch roughly three
times its original length. Your 31/2-inch
rubber band should be okay on a wing
with a 91/2-inch chord.
I use three different sizes of rubber
bands for my models. The smaller or
micro airplanes get No. 16. My park
fl yers that weigh up to 30 ounces get
No. 33 rubber bands. Most of my larger
airplanes use No. 64 rubber bands. If
you have a large Old-Timer model with
a 14- to 16-inch chord, try the No. 107
rubber bands. I purchase these rubber
bands by the bag from one of the large
stationary suppliers, such as Staples.
I use small No. 10 rubber bands in
place of O-rings on my propeller-saver
adapters.
I have some safety concerns with using
rubber bands to hold down wings. If you
are fl ying with glow power, fuel residue
will likely get on the rubber bands. For
that reason, I discard the rubber bands
after each fl ying session.
I had originally thought that with
electric power, because there is no fuel
residue, the rubber bands could be
reused a few times. I
learned that is wrong!
Sunlight and ultraviolet
rays (especially in the
hot summer months)
can cause a rapid
deterioration of rubber bands, so they
must also be discarded after each fl ying
session. Rubber bands are cheap, but
model aircraft are
not!
Don’t use strip
rubber similar to
that of leftover
rubber power
motors. One break
in that strip and
the rubber will
quickly unravel.
This will be
followed by the
wing separating from the aircraft. Use
individual rubber bands. One rubber
band failure out of six will not crash
your airplane.
Scalelike Wing Struts
Q569: I have a wing on my park
fl yer model that is built strong, using
hardwood main spars. I want to add
scalelike wing struts, but since the wing
is already strong, I’d like my struts to be
strictly for appearance’s sake. What is an
easy way to do that?
A569: I recently published a park-fl yer
version of the British homebuilt aircraft
called the Ord-Hume OH-7. On that
www.ModelAviation.com APRIL 2013 Model Aviation 85
FREQUENTLY ASKED QUESTIONS
Bob Aberle
[email protected]
085-087_FrequentlyAskedQuestions_Aberle.indd 85 2/19/13 1:36 PM
airplane, I used a pair of spruce wing
spars. It was strong and didn’t need any
support from the scale wing struts.
I added 1/8 plywood tabs where the
strut penetrates the wing. A
hole or slot is cut into that
plywood insert in such a
manner that the wing strut
passes through to the inside
of the wing. Let roughly 1/4
inch of the strut go inside
the wing. Keep in mind that
this joint is loose. It is not
anchored with any screws
and can move freely.
On the fuselage end of the
strut, I added small metal
tabs to the strut ends that
are wrapped with wire and
epoxied in place. A single
sheet-metal screw anchors
the end of each strut to the
fuselage. These screws go into small
hardwood blocks that I placed on the
inner, lower fuselage sides. The wing
struts tend to float in flight. This setup
doesn’t support the wing, but it looks
good.
Make sure that your struts are
constructed from hardwood such as
spruce or basswood. Balsa would easily
break. Don’t run wire and carbon-fiber
strips along the strut because this could
cause RC problems.
If you get stuck, send me an email and
I will help you.
Specialty RC Connectors
Q570: In recent times I’ve bought a few
of the new and popular RTF micro/
indoor RC models. I found that the
specialty connectors used on many of
these airplanes are hard to find. I like
wiring my own battery cells, but trying
to obtain the correct connector seems
to be a problem. One of the things I
had in mind was to connect two single
LiPo cells in parallel so that the capacity
would be doubled. Where do you obtain
your special connectors?
A570: Most of us who are into micro RC
contact Glen Goode at RC-Connectors.
com for help. The company is based in
Colorado Springs, Colorado. The website
address is listed in the “Sources.”
Glen carries a full line of specialty
connectors for E-flite and ParkZone
products and many others. He sells plain
connectors, connectors with pigtail leads,
adapter cables, and special-purpose
cables. One that I noted is a 2-to-1
parallel connecting cable that allows
you to hook up two single cells, which
doubles the capacity. Your most difficult
job will be to determine what you need
to order.
Glen can easily be reached through
his website. I highly recommend this
company.
SOURCES:
Staples
(800) 333-3330
www.staples.com
RC-Connectors
www.rc-connectors.com