Here are some sketches of the basic structure of the pyramid, from a side-view and a top view. They are drawn approximately to scale. The basic structure is a central tower supporting a large fabric net draped over four guy lines. The fabric will be secured to the main guys (somehow) and will also be attached to a rope running along its perimeter. The rope will be staked down every 15' or so to prevent wind from getting under the fabric.
Choice of fabric material is actively being debated. The main choice is whether we go with a wind-porous fabric like camo-netting or a wind-opaque material like a more traditional cotton fabric. Wind-porous fabrics will have significantly more wind-drag, and wind-opaque fabrics will have more problems with wind-gusts. Which fabric will be more stable is not clear to us. We're hoping to run some aerodynamic models of the structure to get some insight, and will try to contact some structural engineers in Nevada to get local gust-loading factors. If you have any advice, please send e-mail!
The central tower will be 8 sections of painter's scaffolding, totalling 52' high. The scaffolding is 5' by 10'. We will have internal staircases, and minor guy lines set up along its height for support. All of the minor guys will be staked with 4' nails and tensioned with 1" cargo straps. We are considering trying to support the tower without the minor guys, but I'm not terribly confident that it will be stable only supported at the top. Here is the structure of the guys:
Four main guy lines will provide the frame of the pyramid's fabric. Additional bracing between the main guys might be needed to keep the fabric taught -- this is yet to be determined.
The main guys will be stronger rope and tensioned with industrial 2" cargo straps to groups of 3 nails supported by a ring. The three nails will enter the playa at about the same place, but will be at different angles. There will be a metal ring distributing the load between the three stakes. Here is a sketch of this staking technique:
We have not ruled out the use of augers to stake down these main lines.