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The Leonardo Gallery

Satan's Calliope

by Lucy Hosking

© Lucy Hosking. Photo © David Huang.

Satan's Calliope was inspired and conceived twenty minutes into my first adventure at Burning Man in 1998; spawned of Art and Science gone gloriously wrong together in the service of fun. She began as an engineering thesis and became an evolving mechanical sculpture used as the centerpiece of an hysterical performance of fire and light and noise. She is musical in the sense of Stockhausen, loud as Kiss and cannons, dangerous and complicated like aircraft and women.

The calliope is centered around a cluster of 17 acoustic pulse jets, tuned chromatically from G1 through B2. Fourteen aluminum organ pipes tuned from C3 through C#4 fan out on the sides and are blown with propane. Fourteen truck horns, lengthened for tuning, are arranged among the pulse jets with their bells across the top and are also blown with propane. Two large accumulator flares blast from the top for percussive effect. This is mounted on an hydraulic jack which raises and rotates vertically to a height of three meters for playing and retracts horizontally for travel.

The vehicle was once a 1986 Harley Davidson / AMF electric golfcart, and in this incarnation hopes to redeem the good name of Harley from the taint of AMF. The body is sheet aluminum riveted over an aluminum armature. All propulsion and organ systems are powered by 205Kg of lead-acid batteries, which also serve as ballast when the organ is raised. 115 liters of propane carried in two long tanks in the sides is strictly for the organ.

The organ is controlled by an industrial computer using an MC68332 that I designed for a former employer. It reads MIDI from any musical keyboard and determines which valves and igniters to operate for any desired note or effect. There are several regimens for the pulse jets to achieve different effects sequencing air, fuel, and ignition, and plans are a foot to servo the fuel pressure to the MIDI volume control signal. The organ pipes, truck horns, and other effects are simply played by on/off valves. This control information is broken out into eighty or so individual control signals transferred serially to a second small computer in the back of the organ itself where the valve drivers and electrical igniters live.

Fuel is delivered to a manifold through safety valves and a CO2 purge system where it is pressure regulated separately for the pulse jets, organ pipes, and the horns and other accessories. An electric air compressor, reservoir, and regulator provide starting and boost air for the pulse jets.

Every effort was taken to make the system safe, reliable, and legal. Most of the gas handling hardware was taken from the semiconductor industry, like the corrugated stainless flex fuel lines and the manifold valve bodies in the organ. There is almost no non-metal plumbing, and none in the organ itself. The body is open under the machinery to prevent accumulation of unburned fuel vapor, and while it is checked for leaks before every show, the entire fuel system is designed to prevent even a large leak from ever finding a source of ignition.

Satan's Calliope began as my PhD thesis in putting fire and sound where I want them when I want them to go there. She was a study in resonant structures and thermodynamics. She became my introduction to art and a source of pleasure for all who encountered her.

Lucy Hosking, lucyfer at calcentral dot com

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Updated 13 April 2007.

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