126 M ODEL AVIATION
icaRex coveRing: At the 1996 Nationals (Nats), Art Ellis
showed me a sample of a kite fabric called Icarex. His son David
was using it on his F1A towline glider wings.
The material looked like the ripstop nylon often seen on tents
and other camping gear, but it was a good bit thinner. The sample
they showed me was a bright, almost fluorescent yellow-green, but
Art mentioned that a wide variety of other colors were available.
Since then I’ve seen more and more modelers using the ripstop
covering on towline and larger Power models. The consensus
seems to be that Icarex is strong and easy to use.
The range of available colors is a big plus compared to
materials such as Polyspan and clear Micafilm®, in which white is
the only option.
At the 2000 Nats I noticed that Frank Parmenter used red Icarex
on the stabilizer of one of his Jay’s Bird B Nostalgia models. He
said the Icarex only added roughly three grams compared to the
same-size stab covered with Japanese tissue. (Frank double-covers
the bottom surfaces when he uses tissue, to reduce puncture
wounds from landing in rough areas.)
At the Fédération Aéronautique Internationale (FAI) teamselection
finals this past October, I got a close look at several F1C
Power models that were using Icarex. David Halliday, who is now
living in California, used yellow Icarex on the wing, top, and bottom.
Faust Parker went with the white Icarex and painted on
chordwise red and dark-blue stripes, to match those on his non-
Icarex models.
(Since many FAI-type models are similar, and sometimes
identical, in size and shape, many modelers have adopted their
own distinctive color schemes. They use the same design on all
of their models, making identification of the airplanes in the air
much easier.)
There has also been a lot of discussion about Icarex on the
Southern California Aero Team Web site: www.aeromodel.com.
(This site provides the latest information about all aspects of
international Free Flight [FF]. Every serious FF modeler should
have the site bookmarked.) Following is a paraphrased sampling of
some comments about Icarex.
Mike Achterberg has measured a number of samples, and has
learned that the weight can vary by as much as five grams per
square meter because of variations in the thickness of the
polycarbonate coating on either side of the covering material.
Typical weight is near 30 grams per square meter.
This variation also means that the covering is not completely
sealed, and it needs a couple coats of AeroGloss clear dope to
make it airtight. (Charlie Stiles suggests using Top Flite® Flat
Clear in a spray can; he says it is fuelproof with as much as 35%
nitro. Colors are available.)
Jon Davis notes that Icarex is available through a variety of
mail-order kite shops. He says that the best price and service he
has encountered has been at Hang-em High Fabrics (which is also
the source Frank Parmenter recommended).
The company’s Web address is http://citystar.com/hang-emhigh/
ushop. Call or fax at (804) 233-6155 or write to Hang-em
High Fabrics at 1420 Yale Ave., Richmond VA 23224. The
material is less than $10 a yard with a wide range of colors,
including fluorescents.
As are other plastic films, Icarex is attached using a hot iron.
First, a heat-sensitive adhesive is brushed on the wing outline
and the bottom of undercambered ribs; most people use thinned
contact cement. (Pliobond® thinned with MEK [Methyl Ethyl
Louis Joyner, 183 Civitas St., Mt. Pleasant SC 29464
FREE FLIGHT DURATION
Faust Parker uses red, white, and, blue on his F1C models. This
one has white Icarex kite covering; stripes are painted on.
Close-up shows ripstop fabric’s distinct lines. Carbon-fiber D-box
was painted white before covering, to reduce solar heat gain.
May 2001 127
Ketone] is a popular combination, but be sure to read all the
warning labels and use in a well-ventilated area.)
The covering is adhered, then it is heat-shrunk tight. A trim iron
is a much better tool for attaching the covering than a full-size
covering iron. You can heat just the area above the rib without
starting the whole thing shrinking. When the Icarex is completely
stuck down, shrink tight using a covering iron.
Spray or brush on clear dope to seal the Icarex. If you are going
to use a lot of niter you’ll need to use a more foolproof sealer, such
as clear two-part epoxy. Since it is expensive and heavy, use it just
around the wing center-section that bears the brunt of the exhaust
residue and raw fuel from the flood-off system.
As the photos of the two Power models suggest, it is a good idea to
paint the top of a carbon-fiber D-box white, to
reflect the sun and reduce heat buildup that
could soften the epoxy matrix. Make sure that
whatever white you use won’t be affected by
the adhesive you use to attach the covering.
Another approach is to use quarter-mil
chrome Mylar™ panels on top of each Dbox
section. The Mylar™ should stop short
of the leading edge and panel ends, to allow
the adhesive to bond the covering directly
to the wing structure.
better blades: One of the few tools I own
that has stood the test of time is my Little
Giant razor plane. I’ve had the thing for at
least 40 years, and have used it to make
untold Hand-Launched Gliders, a whole
series of solid balsa Wakefield wings, and
even 11⁄2-inch-wide trailing-edge stock for
an A-1 Towline model.
I haven’t used the plane much lately,
partly because I haven’t been building the
types of models that require the rapid
production of ankle-deep balsa shavings.
But the real reason is a lack of blades.
The plane uses double-edge razor blades,
which I don’t think anyone still uses for
shaving. The blades you find now are
stainless steel. They don’t rust, but they are
way too flexible to work well in the plane.
The old Gillette Super Blue Blades seemed
to work best, but were discontinued in the late
1970s. I did find a few packs at drug stores and
at groceries throughout the years, but that
stockpile eventually ran out.
I came across the plane while packing up
my workshop for my recent move to South
David not only paints the D-box, but also paints the carbon-fiber
capstrips and trailing edge prior to covering.
David Halliday used yellow Icarex on his model. Silver-colored
tape along leading edge and at dihedral breaks helps seal joints.
Page of Complete Model Aircraft Manual shows ways double-edge razor blades can be
used to make specialized tools. Column has new source of carbon-steel blades.
128 M ODEL AVIATION
Carolina. I was tempted to throw it away,
since I thought good double-edge blades were
a thing of the past, but a letter from Tim
Goldstein arrived just in time, with a sample
of the German razor blades he is selling.
These blades are made from carbon
steel and are approximately .0034-inch
thick, which is a good bit thinner than the
old Blue Blades at .0043 inch. However, as
did the Blue Blades, these will break easily
to a sharp point for custom-made tools.
(The new stainless-steel blades bend
instead of breaking.)
For those of you too young to
remember, a broken piece of a razor blade
was the standard modeler’s knife in the
days before the X-Acto™. It’s still the best
way to cut or notch soft balsa.
Use a pair of pliers to break the blades
to the desired size and shape. Be sure to
wear safety glasses, and carefully dispose
of all the broken slivers.
A sharp razor blade is also great for
trimming tissue or other covering. On the
polyester coverings such as Polyspan, a
razor blade yields a much smoother edge
than trimming with fine sandpaper.
If you’d like a sample of four blades,
send a self-addressed stamped envelope
and a dollar bill to Tim Goldstein, 13096
W. Cross Dr., Littleton CO 80127.
Prices are $6 plus $1.25 shipping for 25
blades or $20 plus $3.20 shipping for 100
blades. (A hundred blades may seem like a
several-lifetime supply, but believe me, it
isn’t.) Payment must be in US funds;
contact Tim for information about overseas
orders. His E-mail address is
[email protected] or visit his Web
site at www.IndoorDuration.com.
for a bit of nostalgia I’ve included a
photocopy of a page from Edwin T.
Hamilton’s Complete Model Aircraft Manual.
This 1930s book covers all aspects of Free
Flight as it was in the good old days, from
splitting bamboo to making thrust bearings for
a twin pusher from finishing nails.
The page shows using broken blades to
make notching tools and balsa strippers.
Note the use of a “handy cutter” to make
lightening holes in a rib.
(I’ve learned that an easier way to make
a two-bladed stripper is to attach blades on
each side of a piece of hard balsa or
plywood of the desired thickness. An instant
cyanoacrylate [CyA] glue works fine.)
The book includes plans for Indoor and
Outdoor Duration models and solid and
flying Scale models, including one of my
favorites—the Darmstadt D-22.
This is an unbraced biplane with 100%
stagger (the leading edge of the lower wing lines
up with the trailing edge of the upper wing).
There are even plans for a flying blimp,
complete with instructions on how to
generate the hydrogen to fill it.
With a bit of searching, you might be
able to track down a copy of this book at a
public library.
address change: It seems I’m not
the only one on the move. The
National Free Flight Society (NFFS)
publications manager Bob McLinden
has moved back East; his new address
is 9210 Traders Crossing, Apt. J,
Laurel MD 20723.
Check with Bob about ordering any
of the NFFS Symposiums or other
publications. A self-addressed
stamped envelope will get you a list of
what is available.
You can also check the NFFS Web
site for a price list and ordering
information. That address is
http://freeflight.org/.
another nffs Change: After 11 years,
Chris Weinreich is retiring as editor of
Free Flight Digest. The new editor is
Walter Rozelle—a longtime Free
Flighter and professional magazine
writer and editor.
This isn’t Walt’s first stint at the
helm; he edited the Digest for a while in
the late 1960s.
If you’d like to contribute any photos
or articles, write to Walt at 926 Argonne
Ave. NE, Atlanta GA 30309.
unepoxying: Epoxy is a popular choice
for joining metal or composite parts—
especially in highly stressed areas. The
problem comes when you need to undo
an epoxied joint.
Sure you can cut, or possibly break,
the pieces apart, but that usually
damages the pieces. A better way is to
gently heat the parts until the epoxy
softens, then pull them apart.
A soldering iron is the best choice for
small parts or fittings. For larger items,
such as an aluminum nose ring or a
coupler in a motor tube, I use an old
clothes iron set on “linen.”
Try to maximize the area of contact
between the iron and the metal part, to
speed heat transfer. Wait until you see
the epoxy start to smoke slightly, then
twist loose. Do not overheat the parts.
If you plan on using the part again,
clean off the old epoxy with fine sandpaper
before gluing it back in place. MA
