There were a variety of construction needs to be fufulled before we started testing. The most pressing, of course, was the design and fabrication of a scale model and all the associated hardware required to mount it in the wind tunnel.

Secondarily, but important to the success of our project, was the construction of several aerodynamic devices to mount on the model.

Measurement
The first step was to gather all the dimensions we needed to generate a CAD model of the vehicle. We set up reference planes using string and posts, and took data points along the axis and width of the vehicle. We estimate our accuracy at better than 1 cm. The information was stored in Excel to organize the shear volume of information being collected.


(A sample of the data we collected)

Design

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.


(CAD model)


(Conceptual drawing of sliced model)

Construction

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.


(Tracing patterns)


(Trimming with the bandsaw)


(Reinforcing)


(Reinforcing)


(Primering the model and wheels)


(Installing a spoiler)


(Attaching mounting hardware)

Special Features


Aeromotive Movie (16Mb)


Aeromotive Poster (3.5Mb)

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