100 Parsecs

Box Kite (Credit: Pearson Scott Foresman -from Wikimedia Commons)

I love kites, and I've always wanted to try my hand at building some. I built a simple box kite from pine dowels and paper in high school and really enjoyed both the build process and flying (and ultimately crashing) it in the park. So, for the ABC Kite Festival in Austin this year, I decided to build another simple box kite, but as light and as cheap as I could.

If you've only ever encountered the typical diamond-shaped kite, you may be wondering what exactly a "box" kite might be. The simple answer is that instead of being the flat sail or delta-wing shape most often associated with kites, it is instead a rectangular tube structure that operates more like a rigid wind sock than a wing.

The name comes from the fact that the typical design is a long rectangular prism like the one pictured here, with a band of fabric or paper around each end to act as the sail, making a box shape.

Not having made a kite in over a decade, I wanted to make something easy and canonical just to have a bit of fun. I drew up a quick design on paper first, to get a feel for the dimensions. Going for simplicity, I opted to make the cross-spars half the length of the main spars. That way, I could just buy six standard 48'' dowel rods and cut two of them in half to have all of the structural dowel I needed.

To attach the dowels together, I just used some of the nylon kite string to lash everything in place. I had thought about using a nylon hose barb tee fitting to effect the butt joints between the cross spars and the main spars. I think it would have been stronger without being too much heavier, but at Home Depot, one nylon hose barb tee was almost $4 and I needed eight of them, and that seemed like more than the idea was worth, given that all of the other materials together cost under $15. Perhaps I will try it on a future kite project.

Lashing all of the spars together took a couple hours, mostly because I had to figure out a workable technique. I used about 3 to 4 feet of string for every joint. I twisted the string around both spars in a cross pattern, leaving the starting end visible. At the end, I tied the two ends together and singed them briefly with a lighter to keep the knot from coming loose.

To make the spars into the correct box shape, I added rigging lines around the perimeter and across most of the diagonals and pulled them taut, again, singing the knots to keep them from coming undone, as the nylon string I was using was very slick and tended not to hold position very well.

Finally, I needed some sails. I had originally planned to use a light cloth or paper, but I hadn't had time to buy any, and I wanted to test the kite to make sure the design would work and my lashing job was strong enough to keep the kite's shape in the breeze, so I just used plastic food wrap, instead. Initially, I was thinking I would use the plastic wrap for testing and then change to another sail material when I could get some, but I decided I liked the look. In the sunlight, the sails glint when they catch the light just right, otherwise they are nearly invisible, giving the kite a kind of "deconstructed" look. The photos below show the progression from lashed spars to rigging lines to plastic wrap sails. Fully constructed, the kite weighs about half a pound and measures 48'' long by 17.5'' square.

Progression of kite build from just the spars, to spars and structural rigging lines, to complete with sails

With the kite built, it was time for testing. There are several open fields at the research campus where I work, and I grabbed one of my colleagues to help with videography and took it out for a spin. Unfortunately, the wind wasn't particularly steady. Sometimes it was blowing enough to keep the kite aloft by wind alone, but often the wind died to the point that you had to supplement the wind power with leg power, and had to land the kite when you ran out of field through which to run.

I also thought it would be cool if the kite could lift a small video camera and take aerial video. I bought a cheap knockoff GoPro off Amazon and lashed it to the kite with more nylon string. With the camera attached, the kite is a third again as heavy, but it still managed to fly just as well.

When the kite is flying steady, the video is pretty nice, but with it bucking in the breeze, it's not the easiest thing to watch. I also need to experiment with other methods of attaching the camera such that it can look more toward the horizon; when all the camera can see is the kite pilot running through an open field, the video is not particularly engaging. However, I edited the test footage together into a short YouTube video, with a short explanation of the kite build process at the beginning.

After testing the kite, I took it apart and painted the spars silver to make it look more retro-futurist with the clear plastic sails. The original plan for this kite was to take it to the ABC Kite Festival that was supposed to take place on March 5th. I was hoping to use it to get aerial footage of all of the other kites flying at the park. However, both the original date and the rain date got rained out this year. I still plan to take it to Zilker Park on a nice day sometime in the next month and get some use out of it. I will upload more video and possibly post another blog entry when that actually takes place.