The bjurt saga began at Burning Man 2006, so it only makes sense that Burning Man 2007 would mark a major bjurt milestone.
In 2006, I brought a dome of original design.
It was 18 pieces of 10' PVC, 6 stakes, 6 cross pieces, and a six-pointed star at the top, all made from rebar. As you can see, it covers a large area for so little material, and the springiness of the PVC seemed to help it move with the wind.
I bungeed it to my truck rack for stability, and attached a 24' cargo chute for shade. I was set.
Meanwhile, my friends had brought a yurt. I teased them during setup because my materials were lighter, and I was able to do almost all the setup myself. I did need a couple of people for about ten minutes to do the last step, but my friends, the two of them were dragging out the wall (khana), attaching the door, pushing up the roof. They have a good design, but it was still more cumbersome.
On the other hand, they were making a solid, fully-sealed dwelling, and I was just putting up a shade structure. Still, I was pretty smug when I was done.
My dome provided some very nice shade the first day. It was about 90 degrees that day with a little wind. The structure seemed to move a little, but it seemed to "push back" appropriately.
But, alas, pride goeth before the fall. The next day got over 100, and the winds were steady from the west. You may not have noticed, but the PVC I used was the gray electrical variety. I thought the softer pipe would have a dampening effect, and it would be less likely to crack or shatter. And, I was right, it didn't shatter. What I didn't realize is that schedule 40 electrical PVC is designed to deform at 140 degrees, so it can be formed around corners.
While it wasn't 140 on the playa, the combination of heat, light, and wind were enough to do this:
and when the sun went down, it cooled off and hardened that way.
That's right, the BenderDrome became the BenderDroop. It still provided some useful shade, and after I decorated it with some rope-lights, it looked like I meant to do it, but it was not the solution I intended.
I spent a lot of time in my friends' yurt. I talked to them about the construction. In general, I don't like wood. It's not uniform, it dries out. To compensate, you have to have a lot of redundancy, and that means lots of boards and hinges. My friends had to drill hundreds of holes and place hundreds of nuts and bolts. I just don't have the patience for that.
I knew I needed another solution. A better solution ...
When I got home, I started thinking about yurts. I had heard of them before, and even seen one or two in action, but until I spent some real time in a nice one, I didn't realize how comfortable they could be. Properly covered, it's like being inside an RV, but bigger.
I wanted a yurt, but I wanted to be able to carry it around myself. I wanted a yurt, but I didn't want to use wood. I wanted a yurt, but I didn't want to drill all those damn holes!
I started with notion of replacing the wood with PVC and keeping everything else the same. As I looked at weight and cost, it didn't seem that this would be worth the effort. The part count was still too high. The problem seemed to be that the wall was stronger than it needed to be, and thus the weight and part count were higher than needed.
The curved, latticed yurt wall could probably stop a golf cart, and maybe even a small car. That's great if you want to live in something all year, but overkill for a week or two. Not that overkill is a bad thing. I have come up with ways to fortify my bjurt (at greater time, weight, and cost), but a lighter-weight solution was my goal.
Instead of the redundant, overlapping latticework of a yurt, how about discrete, single-scissors panels? Instead of small angles distributed about, how about larger angles at the edges of those panels? It may not be as strong as an arch, but a doubly-cross-braced square panel is not bad.
Still, I wanted it closed, and I wanted it to get rid of the door. I ended up with a scale model that resembled a giant Chinese finger trap, or perhaps an octagonal camp chair base.
Armed with this model, I began work on a full-scale piece. For the poles, I used 1 1/4" PVC with caps on the ends. The reinforcement of the caps seemed to be a good preventative measure. For the panel-to-panel connectors, I bent 3/16" steel bar and drilled holes for for the various poles. For the roof, I hammered the ends of 3/4" EMT conduit and drilled holes for attachment. This was similar to my friends' yurt roof.
When I had this ready, I had some friends over for a test build. The wall structure expanded nicely, but when we tried to erect the roof, I had trouble connecting the last roof poles. I finally got everything connected, but the top ring was tilted quite a bit. This was due to a number of factors, including the unevenness of the ground and the lack of precision in the top ring shape. In a yurt, there are a number of locations to place the roof poles, but in a bjurt, there is only a single choice. The test build was a success, but not a rousing one ...