Radio Control Scale - 2010/05

102 MODEL AVIATION
Also included in this column:
• ParkZone’s BNF Micro J-3 Cub
• FunAero R/C
• Beechcraft Heritage Museum
• Aircraft information at your
fingertips
Finishing scale parts with fiberglass
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Radio Control Scale Stan Alexander
Although applied with a foam brush, the
Nelson paint flattens out well. The PA-11’s
finished cowl isn’t mounted on the
airframe with screws.
Stan layers fiberglass around the wood
cowl in four pieces, working from bottom
to top. The front is last. He uses an X-Acto
knife to cut away extra cloth while the
layup is still “green.”
Fiberglass is great to use to give a wooden structure a consistent surface. Apply a wet
coat of Pacer Z-Poxy, and then smoothly lay fiberglass cloth over it.
The author uses 220-grit sandpaper to smooth the initial fiberglass layup. Then it can be
coated with a second layer of Z-Poxy resin, to fill the weave.
ADDING THE Piper PA-11’s distinctive cowling makes a large difference in this model and
the typical J-3 Cub. The full-scale aircraft had several subtle differences, but the enclosed
engine was one of the major distinctions.
Use spackle on your balsa cowling to fill in holes or “flesh out” the curves where you want
them. I applied a thin layer of spackle around the cowling sides, to make the curves more in line
with the full-scale PA-11. I also added filler balsa to the sides, to bow out the backsides, per full
scale, for cooling exits.
When you’re satisfied with the smoothness and shape of your cowling, gather the materials
to cover the part with fiberglass. These include scissors, medium fiberglass cloth, an X-Acto
hobby knife, 220-grit sandpaper, and coarse sandpaper. You will also need a few 1-inch-wide
sponge brushes, Pacer Z-Poxy finishing resin, and a deck of playing cards.
Mix the two parts of the resin in equal amounts. I use a baby food jar for this. (We have lots
of them from the grandkids, and they are handy to have in the shop.) Using the sponge brush
will help you mix the two parts well.
Cut a piece of fiberglass cloth roughly an inch larger on all sides than the part you are going
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May 2010 103
Above: ParkZone’s Ultra-
Micro J-3 Cub is packaged with
a carrying case to make it easy
to transport safely from the
hobby shop directly to the
flying site.
to cover. Apply the mixed Pacer finishing resin to the balsa in even
strokes, the full length of the part, just on the side on which you’re
working. Start with the bottom, work on the sides and top, and then
finish with the front.
After you apply a wet coat on the part, lay the precut fiberglass cloth
over the wet resin and let it soak through. Use your brush to help this
along.
Use one of your playing cards to squeegee out the excess resin
while making sure you have the cloth exactly where you want it. In a
short time, the fiberglass will be there permanently.
Keep working with the sides of the cowling, then the top, and then
the front. If you are unhappy with the way something looks while the
Pacer finishing resin is still wet, remove the fiberglass cloth and use the
playing card to remove the resin, sand, and start over.
With the first coat on the part, lightly sand the entire cowl so you
can find any high spots or places that need additional filling and
sanding. If there are bumps you don’t want, use the coarse-grit
sandpaper to quickly take these off. But be careful not to take too much
off at once.
Add another coat of the resin to the entire structure, and hold it up
in the light to see if there are runs, high
spots, and low spots. Use the brush to
even these out.
I don’t like the small epoxy brushes,
because they aren’t suited for this
application. They tend to shed bristles,
which always end up somewhere you
don’t want them—usually in the finish.
After you are satisfied with the
smoothness of the surface and you’ve
sanded all of the edges and cutouts, it’s
time to add the primer to the cowling.
As on the rest of the airframe, I used
Nelson paint and primer. Paint the first
coat with another sponge brush. Let it
dry and then rub most of it off with 220-grit sandpaper.
You might be surprised to see some of the bumps and ridges in the
part you’re finishing. Sand these down and add another coat of primer.
When you are satisfied with the primed surface and everything is
smooth, bring out the Nelson Lockhaven Yellow and a separate sponge
for this color. Nelson Hobby Paint cleans up with water. I soak the
Right: For a micromodel, the Cub is surprisingly detailed. The
three-channel version shows simulated ailerons. A 70 mAh, singlecell
Li-Poly provides eight-minute flights.
05sig4.QXD_00MSTRPG.QXD 3/24/10 2:02 PM Page 103
brushes between coats and then squeeze them
dry with paper towels before using them again.
Add the finish color, and sand it lightly after
the first coat. The paint dries quickly and you
can add three or four coats, sanding between
each, in less than a day. Apply the final coat to
the part and hold it up under the light, to make
sure that there are no runs or ridges in the
finish.
You might be asking where the screws are
to hold the cowl onto the fuselage. There are
none; magnets are used in the back of the
cowling. I’ll write more about this next month.
Around Scale: ParkZone has added a series of
small models that are cute, quick, fun, and,
well, fun scale. I recently went to the local
hobby shop and saw several offerings in this
line, including a P-51, J-3 Cub, T-28, Sukhoi,
Me 109, and others. (The T-28 and Me 109 are
not Ultra-Micro size.)
At home I hopped on the Hangar 9 Web site
and viewed the video of the Ultra-Micro J-3
Cub, which comes in two versions: RTF and
Bind-N-Fly. The next day I returned to the
hobby shop and purchased the latter Cub.
If you have a JR or Spektrum DSM2 radio
such as the DX5e, DX6i, DX7, DX7se,
XP9303, XP9503, or 12X, merely charge the
radio system; the receiver arrives installed in
the airplane. The battery and charger come with
the model, so all I had to do was plug the
single-cell Li-Poly into the charger, wait close
to 20 minutes, and the entire model is ready to
go.
The Li-Poly battery attaches with Velcro to
the bottom of the Cub. Doing so turns on the
receiver, which flashes when it’s ready to bind.
That takes only approximately 10 seconds.
If you take your charged transmitter to the
shop with you, you should be ready to fly by
the time you get to the field or the indoor
facility. Charge the Li-Poly battery at the
hobby shop or at the site—not in your
vehicle while driving.
I double-checked the control surfaces
and all went the correct direction. I didn’t
have to program a thing!
The Cub has a lot of scale details for a
model with a wingspan of only 18 inches.
There are engine features, scale tires,
simulated wing ribs, tail wheel, and aileron
details that could be made to work—many
cool things. The airplane has three channels
with rudder setup on the aileron stick.
The box in which the J-3 arrives also
serves as its carrying case, with built-in
foam forms to support the model. It weighs
less than 1 ounce all-up. This diminutive
Cub comes ready to fly for approximately
$89 plus tax.
I think I will get the P-51 Mustang next.
It’s even smaller than the J-3, for indoor
flying or lazy summer evenings outdoors.
The models in this series are sort of like
popcorn, because it’s hard to stop with them
once you start, and in the world of RC Scale
models they are inexpensive.
A report on flying the ParkZone Ultra-
Micro J-3 Cub will have to wait until a
future column; we’re snowed in with more
on the way. I want to fly it outside first.
New Products: For sometime, FunAero R/C
has had a small line of scale kits. You
actually build these models.
They include a British S.E.5a with either
a 60- or 80-inch wingspan, a German
Albatros D.II that spans 60 inches, and a
D.III that has a 65-inch wingspan.
Modelers have been asking for a larger
D.III for a while, and Fun Aero R/C has
been listening. A 1/4-scale version has been
in development and will be released this
summer. Contact FunAero R/C for more
information.
Upcoming Events: The Beechcraft Heritage
Museum will host its annual fly-in for
Beechcraft and other antique aircraft
October 13-17 in Tullahoma, Tennessee.
The facility is beautiful, and it’s a great
place to get photos of your favorite aircraft.
Check out the museum’s Web site or call.
On the Internet: Several of us were looking
at an aviation calendar the other day at work,
and we saw a beautiful AT-6 painted in the
South African Air Force color scheme. It’s
gull gray, with florescent orange on the LE of
the wing, wingtips, and tail surfaces.
One of the guys asked me where that
airplane was, sort of sarcastically. I told him
I didn’t know but thought we could find out.
We got on the Internet and went to the FAA
Web site. From there we went to the FAA
Registry and typed in the N number of the
airplane. A flood of information came to us
almost immediately.
North American built the AT-6G in
1952. It’s registered with a Pratt & Whitney
R1340-series engine and is classified as
Experimental. The owner’s name, address,
and location also came up. This AT-6 is
only one state over from me, so I’m
preparing a letter to the owner to see if I can
go there for pictures when the weather will
cooperate.
If you want to locate any current aircraft,
the FAA Registry is a good tool with which
to work. It doesn’t always produce results,
but most of the time it does.
Remember that an aircraft owner doesn’t
have to help you. But if you ask properly,
most people will be glad to have their pride
and joy photographed.
There are several ways to research the
airframe. One, as I mentioned, is the N
number, and another is the airframe serial
number. I will let you know what I find out.
Fair skies and tailwinds! MA
Sources:
ParkZone
(800) 338-4639
www.parkzone.com
Spektrum RC
(800) 338-4639
www.spektrumrc.com
FunAero R/C
(803) 499-5487
www.funaero.com
Beechcraft Heritage Museum
(931) 455-1974
www.beechcraftheritagemuseum.org
FAA Website Aircraft Registration
http://registry.faa.gov/aircraftinquiry
National Association of Scale Aeromodelers
www.nasascale.org