Sequoia Aircraft Corporation F.8L Falco, Construction Manual

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F.8L Falco Construction Manual 23–15 Revision 4, March 1, 2002
Figure 18
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Install the saddle gussets for the four 30x15 floor supports that are installed between frame
No. 3 and 4. See Figure 7. These gussets are shown on Drawing No. 315 and 155. The
overall dimensions of the gussets should be 25x50 and the gussets should be made from
solid spruce or 6mm birch plywood—glue three pieces of 2mm plywood together.
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Make the two curved gluing strips of spruce which are glued on the aft face of the front
wing spar for the bottom fuselage skin. This skin will wrap from lower side longeron to
lower side longeron across the bottom of the fuselage. A gluing strip is needed on the aft
face of the forward wing spar. This strip can be seen on Drawing No. 155.
Note: The dimensions for frame No. 4 are slightly greater than for frame No. 3. This
means that the gluing strip on the aft face of the front wing spar will be slightly larger than
the contour for frame No. 3. This is a very minor point, but it does merit some thought
and planning.
Also, note that there will be a piece of wood installed on the aft face of frame No. 3 above
the forward wing spar and below the lower side longerons. This is to provide a flat surface
for the installation of the gluing strip.
We are not sure when this gluing strip should be installed. Our best guess is that it should
be installed just prior to the installation of the fuselage skin. This way the fuselage frames
can be float sanded to the precise shape, then the gluing strips may be made and sanded to
match. This will eliminate the difficult job of sanding the gluing strips while they are
installed in the airplane.
Builders using epoxy glue may have one other alternative. Composite aircraft builders use
a substance known as “flox”. This is a mixture of flocked cotton fibers and epoxy resin.
The fibers give the epoxy some strength when it is used in a gap-filling situation. We do
not have any idea how strong this mixture is. Some tests might be in order to see if it is as
strong as spruce. If the flox has sufficient strength, then the gluing strips may be installed
early, and flox used during the skinning.