Shark! (RIP Pele)

In two previous blog posts (#1, #2) I described my collaboration with artist Peter Hazel to construct a mock-up (a “maquette”) of a large sculpture (Pele the Fire Goddess) that he proposed to bring to Burning Man 2022. He submitted the proposal and the maquette to the Burning Man art grant committee in the hope of receiving an Honoraria grant as he has in previous years. But…no luck this year!

Partly due to some perceived issues with his proposed artwork, Peter has now changed his plans to reactivate a self-funded project that we started planning last year: a 20-foot Mako shark made from fused glass mounted to a brushed-steel exoskeleton.

Each of the hundreds of “plates” that form the shark’s skin will be made by melting aqua blue glass billets and casting them into a unique shape, about 10-12 mm thick. The plates will be supported by a 6 mm thick brushed-steel, lattice-like exoskeleton that will be visible in the gaps between glass plates.

The glass plates will be backlit using high-power RGBW LED flood lights of the type I’ve discussed in previous posts. Although ripples in the glass will provide some light diffusion, Peter plans to back the glass with prismatic acrylic diffuser sheet.

Although the backlit glass will look cool, Peter really wanted emphasize (i.e. to light up) the visible portions of the exoskeleton. That was a tough challenge, with the constraint that the external lighting components should be largely hidden from direct view. After discarding several approaches, we settled on the idea of using white LED strips mounted to the sides of “standoff” walls that provide the mounting surface for the glass plates, so that the plates appear to hover above the exoskeleton.

Because the LED strips may be visible from some viewing angles, Peter wanted find a way to avoid the typical “hot spots” created by the discrete LEDs on the strip. Adding diffusers would have required too much space, so I realized that this would be a perfect application for the new Flexible Chip On Board (FCOB) LED strips (example). Although this type of strip is currently only available in white (various temperatures), the LED density can be up to 500 LEDs/meter, compared to 60 LEDs/meter for typical strips. The challenge will be finding a high-quality FCOB strip with an IP (ingress protection) rating appropriate for an outdoor application. I’m currently testing a strip with an IP65 rating (protected from dust and “water jets”), but I may need IP67 or IP68 (water immersible).

The Shark controller will be based on the FLiCr (primary) and SLiC (secondary) boards that I’ve described in a previous post. I’m currently testing some new approaches for power distribution. My original idea of using CAT5 cable for both power and serial data doesn’t seem scalable enough for my larger projects. And on that note, stay tuned for future posts on a new project that’s WAY bigger than the shark, or even Niloticus!

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