The next step involved
translating the 2D plots and data points into a true 3D model. We
used I-DEAS to generate this model, which was then scaled down to
1/3 full size and divided into 13 slices. The slices were printed
on large sheets of paper and trimmed to make our patterns.
We encountered many setbacks
during this phase, including a large time investment in the CAD
model, and several printing problems. We recommend testing the export/printing
process used in your project long before it is actually needed.
(Conceptual drawing of sliced model)
With the initial steps
complete, we moved on to construction of the model.
We chose to use 4 inch
thick sheets of LabLite, a super-dense modeling foam. LabLite can
be cut and sanded much like wood, but is far faster to work with
and thus suited our time limitations.
Each slice from the design
process was traced onto a sheet of LabLite, and then cut with a
bandsaw. The rough sections were connected with wood glue, and sanded
smooth by hand and with power sanders.
We found that the wood
glue provided a very strong bond, but required several days to cure.
Faced with approching deadlines, we opted to reinforce the model
with sheet metal, 2.5 inch screws, and a 1/4 inch steel spike driven
through the suspect sections.
Two spoilers were patterned
after existing designs and hand sanded from blocks of scrap LabLite.
A symmetrical airfoil was borrowed from the Baja Boat project, for
which we fabricated adjustable angle of attack supports.
Painting followed, requiring
two coats of primer and two coats of color to cover the porous foam.
Wheels we painted gray, spoilers and wings white, and the rest of
the model bright red.
Four adustable height
mounting brackets were fabricated to mount the model to the wind
tunnel 'H-Frame'. The H-Frame has 4 vertical pins that can be adjusted
in two dimensions. The mounting brackets are 1/4 inch steel plates
with 4 x 2.5 inch sheet metal screws securing each to the model
and one tube each that slides over one of the vertical pins. Each
tube was drilled and tapped to accomidate a set screw, which when
tightened locked the tube to the pin. These brackets can be mounted
on any horizontal surface, withstand large forces and moments, and
can be adjusted vertically.
We made wheels from scrap
LabLite, and adjustable wheel mounting brackets from Unistrut. To
mount the wheels and hardware, we cut wheel wells and mounting positions
with a Sawzall. All brackets and mounting hardware may be quickly
removed or adjusted using simple hand tools.
All fabrication, modeling,
design, and painting were performed in the FXB Student Workshop
by AeroMotive members, no engineering technicians were harmed in
the making of this model.
(Trimming with the bandsaw)
(Primering the model and wheels)
(Installing a spoiler)
(Attaching mounting hardware)