August 2006 Vol. 23, No. 8 – R/C - RCSoaring.com

which two slots need to be cut in the
fuselage. I checked the recommended CG
range for the Soprano and then measured
the locations for making the slots so that I
could keep the towhook within the range
of adjustment for the CG.
I then chose to add a skeg from Superskeg
to the model, using the V-Skeg (Part SK-4).
This is an injection molded polyethylene
piece with two screws included. The
instruction sheet explains how to go about
making up the mounting plate and also
gives you a template for drilling the three
holes to mount the skeg to the fuselage
The plywood mounting plate was glued
inside the fuselage using
Zap-A-Dap-A-Goo. Once that had cured,
I drilled the three holes needed to mount
the skeg and checked that the fit was good
and properly centered.
The Soprano manual calls for using foam
bulkheads for supporting the pushrods
down the length of the tailboom. The
drawings in the manual are not to scale but
I simply measured up the cross section in
the three locations where the foam would
be located and, using a contour gauge,
worked out the shape and cut the foam
parts as needed. I then determined where
the pushrods would pass through the
foam, and glued in short sections of scrap
pushrod housings through each foam
bulkhead.
To help get them in the correct location
within the fuselage, I made up the elevator
pushrod (using the 0.125 inch diameter
carbon fiber tube) and attached it to the
bellcrank in the fin. I then slid the foam
bulkheads down the pushrod using a
length of spruce marked with the
distances I needed to push in each
bulkhead.
This method worked well for me and gave
me a slop free, low friction support for the
pushrods.
With the bulkheads in place, I drilled out
the nose piece to accept the pushrods and
also installed the antenna tube. I also
drilled two larger diameter holes in the
wing saddle of the fuselage pylon to allow
for future access to the internal towhook
plate should I need to adjust it further and
to give me access for the servo lead to the
spoiler servo. I may also use one of the
openings at a later date for an additional
ballast tube.
With everything in place and final dry fit
check of all parts, I then proceeded to glue
the nose piece to the main fuselage,
placing the epoxy only on the main
fuselage so that as the nose piece was
pushed into place, the epoxy would not
end up on the exposed portion of the nose
piece and leave excess epoxy where it
would cause fit problems for the nose
cone. I used the nose cone to ensure the
nose piece was properly fitted and the nose
cone would fit correctly when the epoxy
had cured.
It was now time to move onto the wing.
The only thing that needed to be done
with the wing was to fit the spoiler servo
and its associated linkage. Timing was in
my favor as the February 2006 issue of
R/C Soaring Digest had just been posted
and Lee Murray’s article “Live Hinge
Spoiler Installation in an Organic RES”
addressed what I needed to do with the
Soprano’s set up. I duplicated Lee’s set up
from the article and had a nicely working
spoiler in no time.
If you are looking for a different source
than the Radio Shack magnet mentioned
in Lee’s article, I have found that there is a
line of magnetic toys available at WalMart
that may just do the trick. Called
Magnetix, these are small but powerful
magnets mounted in plastic sticks that,
along with the provided ball bearings,
make up into various geometric shapes.
You can check out the product line at
.The magnets are
easily removed from the plastic housing
and are as powerful or nearly so as the
magnet available from Radio Shack. The
cost is considerably less as well.
The wing attachment bolts are actually
two different sizes - M4x20mm for the
two main wing bolts, and M4x16mm for
the aft wing saddle location. Be careful to
select the correct bolt size as the shorter
bolt will not pick up the threads if used in
the forward location.
To keep myself from making a mistake at
the field, I went to my local hardware store
and picked up some spares for the field box
and standardized on the longer bolts for all
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