Oldtimer XXL-59
Building instructions - Oldtimer XXL-59
4
The fin and rudder
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The fin and rudder are assembled sandwich-style, with the plywood
parts S10 and S09 forming the core.
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Assemble the fin and rudder from the plywood parts stated above, the
balsa parts S07 and S08 and the ribs S01 to S06. Start by fitting all the
parts together ‘dry’ (no glue), then apply thin cyano to the joints when
you are confident that the parts are aligned correctly.
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Glue the balsa doublers (S11, S12, S13 and S15) to the core using
thick cyano.
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Carefully sand the components. Use a sanding block to chamfer the
trailing edge of the fin and the leading edge of the rudder at around 10°
on both sides of centre, so that the panel can deflect to both sides.
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You will find pre-cut slots in the fuselage for the fin tabs.
The fin can now be glued to the top of the fuselage; it must
be exactly vertical. Check that the front fin strake runs along the fuselage centreline.
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The rudder is attached to the fin using two hinges; the slots for the hinges are pre-cut. Don’t glue the hinges in place
until the model has been covered and painted.
The tailplane and elevator
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The outer frame of the tailplane is assembled from the leading edge V06, the tips V09 and the trailing edge V08. The
elevator is not separated from the tailplane until the structure is complete.
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Pin down the tailplane trailing edge on a flat building board. Note that the leading edge is not fitted until the ribs have
been installed.
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Separate the ribs V01, V02 and V03: start with the two smallest ribs (V03), and immediately fit them in the tailplane
frame.
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The remaining ribs can now be separated from the sheet.
Cut the main tailplane spar V07 (2 x 3 mm spruce strip)
to exact length, so that it fits between the two outermost
ribs (V03), then thread all the ribs onto the spar.
•
When fitting the ribs on the spar please note that the left
and right outer ribs are smaller, and do not feature a
notch on the underside.
•
Distribute the ribs along the spar, so that they are evenly
spaced.
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Place the spar / rib assembly in the tailplane frame, and
press the ribs into the notches in the leading edge from
the top, starting at one end. Don’t use force here,
otherwise you might break one or other of the ribs.
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Once all the ribs are in their notches, continue by inserting them in the notches in the trailing edge. You may find it
necessary to shorten individual ribs if the machine cutter has not made the notches in the trailing edge deep enough.
Tip:
laying a thick strip of wood or a steel ruler against the leading edge and fixing it in place will ensure that the leading
edge stays perfectly straight.
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Now fix the whole assembly to the building board, taking care to keep it
exactly flat. Glue the left and right elevator tip-ribs in the wide slots, as
far outboard as possible.
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The ribs can now be glued to the leading edge, trailing edge and main
spar.
Tip:
a good method of gluing the parts is to apply a little thinned wood glue
to each joint using a small paintbrush or toothpick. The thinned glue
penetrates the joints very well, and produces a strong, rigid assembly.
•
Allow these glued joints to dry out thoroughly, to avoid the danger of the
whole tailplane warping subsequently.
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Remove the tailplane from the building board and carefully press the elevator spar V05 into the notches in the
underside of the ribs. Ensure that the spar is fitted as far forward as possible, and is not twisted along its length; glue
it in place using thin cyano. At the same time check that the tailplane is not warped or curved. If you are not
confident of this, pin or weight the tailplane to the building board again while you glue the joints.
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Repeat the procedure with the spar V04, but be sparing with the adhesive, otherwise the two spars will become
stuck together. Bear in mind that you have to separate the spars V04 and V05 again later.
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The final step is to install the half-ribs V01b, which form the elevator tips.
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Carefully sand the tailplane overall, taking care not to alter the airfoil.
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Glue the in-fill panels V10 and V13 in the central rib bay.
