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It's tall-tail time now, so move to the
rear of the fuselage. Most ARFs have a vertical balsa post at the rear
of the stabilizer opening that must be removed. A photo shows it being
cut by a hobby razor saw.
Once the post has been removed, mark the
center of the stabilizer and the rear fuselage. Position the stabilizer
in place, aligning the two marks. Push a large hobby pin into the center
of the fuselage top just in front of the wing saddle—the large opening
into the fuselage.
Keeping the stabilizer aligned with the rear fuselage
mark, adjust the stabilizer tips until they are equidistant from that
forward pin. Once the stabilizer is aligned, mark the position of the
fuselage sides on the stabilizer. Don't use the red marking ink shown
(that is done only for photo effect) because it leaves a mark; use a
pencil.
Remove the stabilizer and use a small soldering iron to cut and
remove the covering from both sides of the stabilizer. Do not use a
modeling knife; that will likely damage the wood's integrity.
Now for
the part where you must be careful. The horizontal stabilizer needs to
be aligned as noted in the preceding: centered and straight. However,
one even more critical alignment must be set; the stabilizer must be
mounted in the same horizontal plane as the wing. If not properly
aligned, any elevator input will also induce a rolling moment.
There are
several ways to make this crucial alignment. One is to mount the wing
and stabilizer, and make sure the alignment is correct by looking from
the rear. Surprisingly, this is an accurate method.
Another way is to
put the flat-bottomed fuselage on the level workbench, install the
stabilizer, and use a small, light, plastic appliance (two-way) level.
Put a 9-inch torpedo level at the rear of the wing saddle to make sure
the fuselage is level.
Fortunately for today's modelers, the stabilizer
slots in the fuselage are usually built well. At most, a 1/64-inch shim
may be needed on the "low" side to align the stabilizer. This Hobbistar
60 needed no alignment correction.
My standard is to have less than 1/16
inch of stabilizer misalignment for trainers and high-wing aircraft with
dihedral. Sport aerobatic airplanes benefit from having less than 1/32
inch of misalignment, and competition—Scale and Aerobatics—aircraft must
not have any measurable misalignment.
Once aligned, install the
stabilizer with 12-minute epoxy to allow time to regain proper
alignment. Brush the epoxy only onto the fuselage mounting points to
ensure a clean job, and wipe away any excess.
When the stabilizer
installation is complete, you may want to apply some 1/2-inch-wide
covering strips to seal the fuselage/stabilizer joints. Do this before
you install the vertical fin.
Test-fit the vertical fin in the fuselage.
Mark and remove the covering from the areas that will be glued, just as
you did on the stabilizer. Use a hobby square to make sure the vertical
fin is vertical in relation to the level stabilizer, and epoxy it in
place.
Install the elevator and its control horn just as you did for the
ailerons. Attach the rudder to the vertical fin. Make sure the control
horns are square against the control surfaces' LEs and that the holes
are over the center of the hinge line.
The control rods are installed in
the same manner as were the ailerons'; they are just longer and slide
into tubes inside the fuselage. Make the servo connections as you did
with the ailerons. Be sure to center the control surfaces.
Click on photo to view large image with caption
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