John Cadman & Greg Neil~ Grade 6 Math/ Science Teachers
Calgary Science School
This is a design for an open ended wind tunnel. This means the fan pushes air into the tunnel instead of pulling it out the end. Assembled it is 4ft long, 2 feet wide, and 2 feet high. Our hope in building this tunnel as we did was that in future it would require no tools to re-assemble. This design is a larger version of a tunnel original built by Louis Cheng at CSS using an old computer fan.
How it works in the classroom:
The challenge to students is two fold. They will design and build a wing/air foil that will generate the most lift in the wind tunnel and achieve the greatest distance outside the wind tunnel.
In the tunnel students affix their wings to a fuselage provided by the teacher. The fuselage is attached to a scale. This allows us to control the angle of attach of the plane and thus limit the lift produced to that of the air foil. As lift is produced the weight (force) shown on the scale should decrease. This means lift is being created. The less weight registered on the scale means more lift.
We decided to test the planes outside as well to encourage students to design a functional wing, not just one that would pass a wind tunnel test.
The students were provided two short pieces of dowling. This was to act as wing spars and allow us to slot their wings into an existing fuselage.
– 2 sheets of foam insulation (1 ¼ in x 24 in x 90in)
– 1 sheet of plexi-glass (3mm x ?? x ??)
– 1 20in. box fan (ours has 3 speeds) – $20 at Rona
– 1 sheet Egg Crate ceiling light cover
– Gram scale
– Styrofoam air place ($1.25 at Dollar Giant)
– Utility knife
– Glue gun (one with a Low setting is preferable)
– Screw driver
1. Cut the insulation to desired length. We cut it in half at 45 inches. This will act as the base of the tunnel.
2. At on end we traced the bottom of the fan on the Styrofoam and then cut out a channel so the fan would sit flush with the tunnel. (In hind sight this was excessive. Gluing a strip of foam onto the base in front and behind fan).
3. Tape plexi-glass to side of fan, and glue strips of Styrofoam to base on either side of plexi-glass to create a channel for it to sit in. This side acts as your viewing window.
4. Using the left over foam, repeat step 3 on the other side of the fan to create a second (non-clear) wall.
Optional: Cut the Egg Crate so it will fit inside the tunnel, 6-8 inches in front of the fan. We layered our Egg Crate 3 deep. The goal was to create a Wind Diffuser to settle the air into a stream. To affix the crate glue 2 verticle strips of styro-foam to the walls of your tunnel. One on either side of the crate. Thus creating a channel to slide the grate into.
6. Cut a section of foam to sit on top on the tunnel in order to seal space on top of tunnel between fan and Egg Crate Grate.
7. At this point your tunnel is done, unless your decide to add a ceiling to the test section of the tunnel.
Note: We removed the built in grate on the fan on the inside of the tunnel as it slowed down the air flow. The egg grate will protect students and their project from the fan blades.
Remove the grate from the fan on the inside of the tunnel.
Have fun and let us know what changes you have thought of.