Satan's Calliope

Satan's Calliope (Fig. 1) was inspired and conceived 20 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 a hysterical performance of fire and light and noise. She is musical in the manner 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 using 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. All of this is mounted on a hydraulic jack, which is itself mounted on a golf cart chassis, that raises and rotates vertically to a height of 3 meters for playing and retracts horizontally for travel.

Fig. 1.

Lucy Hosking, Satan's Calliope, aluminum and steel, 1999-2000.

© Lucy Hosking. Photo © David Huang

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

The organ is controlled by an industrial computer using an MC68332 microprocessor 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 by which the pulse jets can achieve different effects by sequencing air, fuel and ignition, and plans are afoot to servomechanize the fuel pressure in connection 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 about 80 individual control signals transferred serially to a second small computer in the back of the organ itself, where the valve drivers and electrical igniters reside.

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

Every effort was expended to make the system safe, reliable and legal. Most of the gas-handling hardware was taken from the semiconductor industry, including the corrugated stainless flex fuel lines and the manifold valve bodies in the organ. There is almost no nonmetal plumbing-none in the organ itself. The body is open under the machinery to prevent accumulation of unburned fuel vapor, and while I check it 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 Ph.D. thesis in putting fire and sound where I want them when I want them. She started as a study in resonant structures and thermodynamics. She became my introduction to art and a source of pleasure for all who encountered her.