Project: Wind Tunnel

One night laying in bed, I often can’t fall asleep because I am thinking about mechanical things, I was thinking about wing designs. Many PhDs, professors, and companies are trying to think of innovative aircraft design for increased performance. I had some interesting ideas which I had never seen before and wondered if they had any merit.  I decided I wanted to throw my hat in the ring. The only way to determine if they are any good is simulations in a computer program or a wind tunnel, for me then, wind tunnel it is.

Ever seen those commercials with cars and smoke lines going across their body? Those cars must be really fast if smoke can go over their roofs! Anyways, they were in a wind tunnel. Wind tunnels are built to determine how objects behave as they pass through the air, only this time the objects are still and the air moves around them. Wind tunnels can be used to study a host of very interesting questions about how fluids (air is considered a fluid) work and the way things we build interacts with it. Investigating my wing designs through a wind tunnel provides the possibility to create developments in aircraft designs and promises the ability for me to learn more about fluid mechanics. 

Originally, I bought a great and beautiful piece of poplar wood from Home Depot’s 85% off cart. It was 1″x9″ and about 6 feet long. I bought it not knowing what I was going to do with it, I just thought it was wonderful. I don’t remember what came first deciding to build a wind tunnel, or finding the sheet of Plexiglas. Well, I found a sheet of Plexiglas about 3 foot square in my basement and determined to build a wind tunnel! From the get-go, I understood this would not be a University Research Lab quality, size, or speed, but just enough to take some basic, low accuracy measurements which could roughly characterize performance of my wing or aircraft designs. Therefore, I did a little online reading: http://www.grc.nasa.gov/WWW/k-12/WindTunnel/build.html and got started.

It would be best for the wind tunnel to be as large as possible and be round, but I am limited in shape, height, width, and length to my piece of poplar. With a middle section of Plexiglas on three sides, I calculated how long the wind tunnel could be given my length of poplar. It turned out to be about 3 feet. The bottom entirely poplar and the two sides and top about a foot of poplar then a foot of Plexiglas then another foot of poplar with some overlap between wood and Plexiglas for attaching the two. I measured and cut the poplar. Then using a router, cleared out space for the over lap of Plexiglas and wood. I cut the Plexiglas using a hand saw, and wow I can’t stand inhaling the Plexiglas dust. I assembled the sides and top using epoxy to attach the Plexiglas to the wood. With each side and top assembled, I decided to make the wind tunnel wider than taller, creating joints where the sides but up against the edge of the top and bottom. I pre-drilled four holes at each joint and used 2 inch wood screws to attach all four parts.

The biggest difficult came in the joint between the top and two sides. I wanted the Plexiglas of the top to hug the sides at the joint to reduce leaks, but in doing so, made it too wide. Therefore, when I screwed it together the epoxy gave way on top as the Plexiglas bowed inward.Bummer.

What to do. I had already applied caulking to all the joints and wanted to be clever and find a solution outside of disassembling the entire thing. I  took out my trusty electric drill and drilled holes along the edge of the Plexiglas where it was too wide. Then using wire cutters, cut the remaining material between each hole, eliminating the problem and not damaging anything caulking couldn’t fix! I had never caulked anything before this day, but found it pretty easy and messy.

I finished the day(s) telling people I had a Wind Tunnel, and yes, I literally had a wind tunnel, merely the tunnel. Exciting and possessing a wind tunnel, bravely imagine what one day may be tested, and boldly think what interesting things may be learned!

Here is the created Tunnel, sorry not the best picture.

Epoxy after Plexiglas bowed inward.

Epoxy after Plexiglas bowed inward.

Square tunnel

Square tunnel.

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