## Friday, April 17, 2009

### Wind Power Unit Study - Day 5: Building a Wind Turbine's Tower

Since a wind turbine has to be mounted on something, our study today focused in on tower design. A tower for a wind turbine needs to be strong while still maintaining as small a footprint as possible. The land around many wind farms is still used for agricultural farming.

We began construction of our own tower, made out of paper, per the instructions we found at www.windpower.org/en/kids/teacher/turbkit.pdf . Ultimately, this exercise can lead to the construction of a working turbine, made out of paper, which can be used to run a series of experiments. We began by building one of the three cubes needed for the tower.

The materials needed are fairly simple:

• 16 sheets of European letter sized typing paper (A4) - The website provides instructions for cutting down American legal sized paper, if you can't get your hands on the European size.
• 8 bolts, 3/4'' by 3/16'', with accompanying washers and nuts.

• A glue stick
• A paper punch
• A wood dowel 5-6mm in diameter (we used two pen's stuck together)

The paper is folded (short ends together for short sticks - long ends together for long sticks), leaving about 1/4'' at the top for applying the glue. Then it is rolled over the dowel (for smaller children, you will have to do the rolling for them. It's not at all as easy as it sounds!), and glued. The ends are flattened and punched, with a hole punch. One cube requires 12 short paper sticks, and 4 long paper sticks.

Finally, the sticks can be bolted together into a lattice pattern cube. Once the cube is made, it's strength can be tested. We placed a board across the top of the cube to evenly distribute weight, then we started adding books.

Our cube comfortably held 38 lbs...

...but collapsed at 41 and 1/2 lbs!

The children took turns tweaking the various sides of the cube to test the strength of the sides with triangles, verses those that were empty. Then we finished off by watching The Magic School Bus Under Construction, which nicely explains the concepts of strengthening techniques in construction. Now I just have 24 more sheets of paper to roll up, so they can complete the tower (not to mention polishing my table - I maybe should have covered it before collapsing a cube with 41 and 1/2 lbs of books and wood)!

But it's still great to be a homeschooler!