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a Wood Fuselage
this page, I've kind of jumped ahead some. Since I have already
done much of the preliminary calculations and sizing of the
airplane, I jumped ahead to drawing the fuselage. This is where
it really gets fun for me.
you have ever built a flying model airplane out of balsa sticks,
you will see that a full size wood airplane can be built the
same way. Wood is one of the best building materials for an
airplane even in the days of aluminum and composite construction.
With the JayBird, I will used Clear Vertical Grain Douglas Fir.
Many wood airplanes have been built out of Spruce in the past
which is an excellent, lightweight, strong material. Spruce
is cost prohibitive in our society. Douglas Fir is much less
expensive. It is also quite a bit stronger than Spruce but it
is also heavier. For me, the trade offs are acceptable.
airplanes are generally built by first building a ladder type
truss. When both sides of the airplane are built, they are joined
together at the front of the fuselage and then the back of each
side is pulled together to give the airplane the streamlined
shape. Then each of the horizontal formers are glued into place.
Before the first fuselage side is built, the builder must have
a perfectly flat work surface so that each side will be perfectly
flat and square.
the JayBird, we will basically be building a tub or a structure
that looks kind of like a canoe with one flat end. This tub
will carry all of the fuselage loads. The cowling, windshield
and turtle deck are
all mainly on the airplane to streamline the structure.
uses the basic truss design that most wood airplanes use.
the drawing above, the bottom two images show what the fuselage
tub will look like when completed. The bottom image shows how
the side structure is layed out in the beginning steps of construction.
The top and bottom longerons are laid out on an extremely flat
table. Then the vertical formers are glued into place. Two sides
are built, a left and a right side. When the glue is completely
cured, each side is laid upside down on the top longeron and
the front, horizontal formers are glued and clamped in place.
The first four formers are glued into place. When the glue is
cured, the back of each side is pulled together and the rest
of the horizontal formers glued in place. After all of this
comes the tedious task of cutting and gluing in gussets
at each joint. The gussets
will increase joint strength immensely.
drawings above were done in AutoSketch. The JayBird is being designed
in 2D, or two dimensions. Then the airplane will be "built"
with a 3D parametric modeling software. By designing the airplane
in three dimensions, I will be able to make sure parts fit perfectly
without having to build an actual prototype
of the airplane. Also, by doing this, I can know what the airplane
will weigh when it is built and by using finite element analysis
programs with the 3D drawings, I can see if there weak spots
in the airplane or if there are parts that are "over-built".
I can also run wind tunnel tests on the airplane without having
ever built a prototype. The cost savings are substantial by
using modern computer software!
the fuselage tub is completed, the firewall, instrument panel
and turtle deck can be added. The tub will be covered with 1/8
inch Birch plywood. Then, fiberglass cloth and resin will cover
that. This will give an incredibly light and strong structure.
stages of building the fuselage tub is drawn and actually "built"
using 3D modeling computer programs.