Sequoia Aircraft Corporation F.8L Falco, Construction Manual

Page: 76 / 423

l
F.8L Falco Construction Manual 10–11 Revision 4, March 1, 2002
quite long, and this is desirable. To bend the plywood, lace the rubber bands back and forth over
the nails of the two 20x20 pine pieces. The first couple of lacings will do little to bend the
plywood, but as you work your way down the leading edge, the cumulative pressure of the bands
will bring the plywood down into place. If a single pass is not enough, then lace back over the
nails again and again until the plywood bends into place. Ordinarily, soaking the leading edge of
the plywood in water is all that is required, but the use of a steam iron in this situation would
greatly speed things up.
Figure 11
After the leading edge plywood is bent, it is kept clamped in place for a couple of days until dry.
The plywood is then removed from the airplane and allowed to completely dry. When the skin is
glued to the airplane, the same method with the rubber bands may be used to clamp the skin in
place. After the glue is dry, the extra plywood and the 20x20 pine is cut away. The same method
is used for the skin on the other side of the wing, or tail.
A few builders complain that these methods are not completely to their liking, since the plywood
tends to lift from the rib while the leading edge radius is being bent. Another method—and the
one used on the production Falcos—is to glue the first skin in place without bending the leading
edge radius or getting any glue on the leading edge strip. After the glue is dry, the leading edge of
the plywood is bent by wetting the wood with hot water and using a steam iron. Pull the plywood
over and nail to the leading edge strip. After a couple of days, remove the nails and allow the
entire assemblage to dry completely. Then, stuff glue under the leading edge of the plywood and
nail down. Then proceed as shown in Figure 10.
The fuselage has slight compound bends on the side skins around the cockpit. In this case the
plywood is clamped to the fuselage frames. As an alternative method, you may make a simple
form to bend the skin over. Don’t worry about this now, instructions for bending this plywood be
covered in the appropriate chapter.
Clamping Methods
Figure 12 shows the most common method of clamping a rib to a spar. A block of wood is
inserted into the gusset pocket of the rib, then two pieces of wood are screwed together as shown
and a clamp is used to hold things in place.