3
fit wing ribs to the drawing by moving inboard and outboard slightly with the spar. Engage the tip
trailing edge assembly notch to the end of the spar. The main spar dihedral and polyhedral joint
ends will not touch until the dihedral is rigged at assembly.
The tip trailing edge assembly should be off the building board from the polyhedral break
outboard. It is supported at the spar end by the removable tab on the spar lower edge. Ribs
W-3 and W-4 also have standoff tabs to maintain the proper assembly rig, and the trailing edge
assembly should be set to assemble flush with the top edge of these ribs. This also applies in
general for all wing ribs-set the top edge to be flush at the upper surface of the trailing edges.
The reason for this will become apparent during the final sanding and shaping step. If
necessary, add scrap balsa shims under the tip trailing edge assembly to support during the
bonding assembly. Position the forward edge of T-4 to be centered on the aft surface of the
leading edge bow. This will create a slight undercamber and washout effect in the tip, which is
highly desirable.
Once the outer wing panel is prefitted and all parts positioned, bond in place with light application
of thin CA. Do not install the polyhedral joint rib W-1 yet. Dry assemble and best fit all the
inboard wing panel W-1 ribs to the drawing location. Do not install the center dihedral rib W-1
yet. When satisfied with the inboard wing panel dry prefit, bond the assembly with light
application of thin CA adhesive.
Install the 1/16 square turbulator spars in the outboard wing panels. Allow excess material for
scarf joint overlaps at the polyhedral joint location. Bond the spar ends to the wing tip and ribs.
Do not bond spars to rib W-2 yet-this will make it a little easier to assemble the polyhedral joint
and W-1 joint rib. Install the inboard panel turbulator spars, again allowing for material excess at
the dihedral and polyhedral scarf joint locations.
Carefully remove an outboard panel from the plan. Use the outboard joint rib gauge from the
laser cut sheet to install the joint rib W-1 against the end of the inboard wing panel still on the
board. Align carefully, but do not glue yet. Position the outboard wing panel onto the plan again,
making sure to pass the loose ends of the turbulator spars over the top of the joint rib W-1.
Carefully block the outboard panel tip off the building board to the 1-5/8" dimension shown on the
drawing. Position to obtain contact with the end of the main spars, trailing edge and leading
edge. Once the rig is established and all joint members are in contact, bond the trailing edge joint
first, then the main spar/rib joint, and finally the leading edge/rib joint, with the rib positioned at
the angle maintained by the gauge.
The turbulator spars should be overlapping at the spar notches in the joint rib W-1. Position one
on top of the other over the rib notch, and using a very sharp razor, cut both spars at the
approximate angle shown on the drawing, straddling the joint rib. The scarf joint should fall into
the notch, and the tapered edges in firm contact with each other. Apply thin CA adhesive to
solidify the joint to the rib and each spar. Repeat for the remaining turbulator spars and rib joints.
The same basic process applies to the dihedral rig of the wing center. Leave one side flat on the
building board and block the other side up to the dimension noted on the drawing, after
positioning the wing center joint rib W-1. This completes the basic wing assembly.
Sanding the Wing to final shape
Sand the lower surface of the trailing edge to blend into the lower contour of the wing as
determined from the wing ribs. If the ribs were installed flush to the upper surface of the trailing
