A Table-Top Wind Tunnel You Can Build!. Michael Mackowski Phoenix Section American Institute of Aeronautics and Astronautics October 2013. AIAA’s Recent Outreach. Science and Technology Festival Wind Tunnel display APS Back to School resource fair
American Institute of Aeronautics and Astronautics
This cardboard wind tunnel is just a tool for the classroom.
Remember we are engineers, so what I will describe is simply how to build it.
We are not trained educators, so we cannot tell you exactly how to use it in your school.
We are endeavoring to develop some example lesson plans and classroom exercises, however, but we have nothing specific at this time.
All of the info in this presentation is on our website.
The next thing needed is a grid to minimize turbulence.
The fan is pulling air into the wind tunnel, but it tends to twist the airflow because of the rotation of the fan blades.
To reduce this effect, you need to add a grid on the upstream end of the air flow, on the opposite side from the fan.
The final feature is perhaps the most important, but we found it to be the most difficult to design.
The desire is to install a wing section (airfoil) to demonstrate lift and actually measure it. The minimum goal would be to show that a real airfoil shape generates more lift that a flat slab.
After several sessions of trial and error, we came up with a balance design. This concept has the weight of the wing on one side and a spring on the other side.
You can add some weight (here, it is a small bag with fishing weights) to balance the arm, per the sketch below.
So how do you build such a balance? We tried to keep it simple and inexpensive.
The initial version used “arms” and the wing support made from ¼ inch thick foamboard.
In our design, we used a spring from a ballpoint pen. Pieces of paper clips attach the spring and bag, with the ends just poked into holes in the foamboard.
The arm holding the wing actually has a slot so that different airfoil shapes can be swapped out. Sewing pins are used to secure the different wings to the main arm.
The wing section was made from a base of foamboard. An airfoil section was cut from more foamboard and glued on. Two sheets of cardstock were used to cover the wing. A toothpick pivot was used to attach the wing to a support stem.
The more recent version does this with dowels.
The arm holding this flat slab pivots on a straight piece of paper clip wire taped down. Another piece of wire pokes into the support arm to adjust the angle.
The main dowel is the pivot for the entire balance, and it rotates freely in holes punched in the sides of the wind tunnel (photo below). Again, the exact height or location is not critical.