In many ways the story of the Nebula begins at the Hilton Anatole, in Dallas, Texas. The owners, Crow Holdings, who commissioned this sculpture, are passionate about the arts. In fact this hotel was first built in 1979 partly to showcase their extensive collections of both Asian antiquities, and modern sculpture. As part of a large renovation this year, their architect EDG suggested a suspended kinetic artwork in the Atrium II, and organized a competition, to which I was invited.
Atrium II is monumental and magical, and above all I wanted to do it justice – gathering together the existing elements of steel, sparkle, grand scale, into a fluid and mesmerizing sculpture. I spent a month looking at overhead large scale forms in nature – flocks of starlings, clouds in a sunset. After kicking around various ideas, I settled on a hundred-foot long diamond fitted to the long axis of the atrium. I decided on a multi-tiered hexagonal structure with a Yin Yang wave pattern to give the lower part some vertical volume. The layout of the existing ceiling trusses suggested a 40’diameter ring, and looked like it could elegantly support four hoist motors to lift the sculpture into place. I played around with tiling the hexagonal pattern and decided that 445 cables would be enough to offer good fluidity, and yet still be spaced around the top ring with enough room to design pulleys. I figured a tension grid could support the distribution of the cables to the lower artwork which would consist of thousands of sparkly elements, though I wasn’t quite sure what those would be. A friend of mine, Costis Alexakis, helped with initial drawings and a rendering.
When I was awarded the commission the reality of having to make something of this scale hit me and I reached out for help. The complexity suddenly seemed quite formidable, and I had absolutely no idea how to approach a steel structure that was going to weigh thousands of pounds. I asked a local museum designer, Joe Ansel for help, and he generously offered indispensable guidance and wisdom about approaching this commission. Among other things Joe introduced me to the fabrication company Gizmo Art Production, Inc, in San Francisco, owned by Mark Sabatino.
Above all my hat goes off to Mark Sabatino for his courage. It simply takes a lot of guts to take on a project of this magnitude, with all the unknowns, personalities and tens of thousands of parts. But he was excited, said sure, and never wavered. Despite Gizmo’s large warehouse, when Mark discovered that the truss could not be assembled, he tore down a few walls to make it work. Thanks Mark! I couldn’t have done this without you.
Besides Gizmo’s crew of welders and designers, Mark introduced the mechanical engineer Michael Prados from Ideal Mechanism. The hotel was already working with structural engineer Martin Graves from Hunt & Joiner who agreed to analyze the ceiling and sculpture frame, but we needed more help.
Michael dove in and without his design work the Nebula would have never gotten off the ground. Besides taking on the entire structure and designing the ring, spokes, flanges, motor, swing arm and thimble, most of Michael’s work centered around the cable net. It turns out it’s no small task to design a net which has to span 100 feet and support variable loads at hundreds of nodes. After analysis Michael recommended a net made of 1/8″ cable crossed with 1/4″ cable tensioned to specific tolerances, and then designed a truss to withstand those forces. Craig Briton from Gizmo then took this design and began making what turned out to be hundreds of pages of shop drawings for fabrication.
Meanwhile I was stuck on what material to use for the lower artwork. A warm color would work well in the atrium, but I needed a hard to find combination of transparency, sparkle, lightness, and durability. One day I was leaving my house and a bicyclist rode by and the sun caught the wheel reflector with a brilliant flash! Ah ha! I thought bicycle reflectors!! That very day I called up Cateye who said that they would sell 14,000 curved amber wheel reflectors.
I began to think about the cables and realized that it would be helpful if we knew all the cable lengths as well as the force each cable was exerting on the grid and thimble. It occurred to me that if we also knew the angle that each pulley should be at to direct the cable to the correct place these could be set ahead of time with a jig rather than trying to do it experimentally in the field. The first challenge here was to map all the cables. Costis helped me superimpose a Yin Yang pattern over a plan of the Nebula and I stared at it for a couple days. The mapping had to accomplish several things: It had to provide movement which was varied and pleasing to look at, it had to be uniform movement, so no adjacent links would pull apart, and the whole thing had to be counterbalanced. After I was satisfied with the mapping there was a series of overlapping 3-d trig problems to calculate all the lengths, angles and forces. I learned Excel so that I could do the math once and apply it to all 445 cables. Since there were various dimensions and weights which were not yet locked down, I designed the spreadsheet around variables, and simply put in correct values as they became known.
As I continued to make prototypes and sketches of various parts, Michael and Martin completed the scope of their engineering, and Eric Reedy and others at Gizmo searched the internet for just the right fastener and material, Craig was finally able to complete the design with a big stack of drawings showing how everything fit together.
You must be logged in to post a comment.