December 5th, 2004


Air Power

Air Power

A German pneumatics firm called Festo is pulling the piston out of the industrial age. Next up: Reinvent shock absorbers, scooters, and aircraft design, then build an inflatable castle in the sky.

By Christopher Dickey

It pleased the Greeks, as well as other nations, to call wind, breath, pneuma, that which they vaguely understood to be respiration, life, soul. Thus in antiquity soul and wind were in a sense the same thing; and if we were to say that man is a pneumatic machine, we would only be translating the Greeks. - Voltaire, "L'Esprit," in Dictionnaire Philosophique

One by one, Axel Thallemer set the machines in motion. The bread-and-butter machines, as he called them, little demonstration models of pneumatic screw sorters, furniture stress testers, robotic assembly-line grippers, all running on air. Ssshhh-plok! Rrrrrrrr-pip! Pneumatic doors opened and closed, steel claws placed chips on boards, air jets blew bolts off spiral conveyors, and the great hall resonated with sounds from a Walter Mitty daydream. Pocketa-pocketa-queep-pocketa-pocketa: a percussive hissing, plunking, shushing symphony of pneumatic performances so mesmerizing that, at first, I didn't hear the building begin to sigh.

"Listen," said Thallemer, chief of corporate design at Festo AG & Co., the privately held German power tool and pneumatics firm. "Do you hear?" The warehouse-museum where we stood was itself a pneumatic wonder, its walls and roof and Y-shaped cyber-Gothic flying buttresses not only inflated but held in dynamic tension by artificial muscles. Three computers read the ambient wind speed and temperature, flexing the pneumatic sinews as needed to keep the walls taut and erect, bleeding air from the roof when it grew warm and began to expand. This "Airtecture" has withstood sustained gale-force winds roaring through the Swabian hills of southwestern Germany. But today was calm. "The sun has come out," said Thallemer. The panels high above our heads exhaled languorously, like a thing alive. Thallemer sighed, too. "Most of my time is not spent on the fun stuff," he said.

By "the fun stuff," Thallemer meant the astonishing creations coming out of Festo's design department - a vehicle called the Citycyc, the six-legged AirBug, the Airtecture buildings - inventions that could revolutionize the way we inhabit urban streets and other hostile environments. In partnership with subcontractors such as Swiss inventor Andreas Reinhard, who runs a small company called Prospective Concepts, Festo has found new ways to harness the power of air. It is opening up possibilities for pneumatic technology comparable to the revolution that occurred in electronics when transistors replaced vacuum tubes. Combining air-filled "membranes" with "fluidic muscles," Festo is producing prototypes and working models of airships and inflatable buildings, as well as pneumatic runabouts and kite-propelled skateboards.

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Prospective Concepts: Tensairity

[Swiss design firm with a variety of fascinating technologies under development.]

tensairity bridge

Pressure Induced Stability:
From Pneumatic Structures to Tensairity®
Rolf H. Luchsinger, Mauro Pedretti* and Andreas Reinhard
prospective concepts ag, Flughofstrasse 41, 8152 Glattbrugg, Switzerland
and *Airlight Ldt, Via Croce 1, 6710 Biasca, Switzerland
Pressure induced stability is very common in nature, although often not perceived. The green
tissue of plants is supported by the cellular turgor pressure. This becomes most obvious when
plants wilt due to water shortage. Technical realisation of pressure induced stability is found in
tires, hot air balloons, airships and airhouses, where air or other gases are used as compressed
media. These pneumatic structures do all have a simple geometry close to a sphere, a cylinder or
a torus. Either they cover huge volumes with low pressure as in the case of airhouses and airships
or have small volumes and high pressure as in tires. In recent years, prospective concepts ag has
systematically investigated pneumatic structures in the intermediate pressure range. Technology
demonstrators such as a pneumatic park bench or the pneumatic airplane Stingray are the
offspring of these studies. It was shown that almost any shape can be made with pneumatic
structures and that the load bearing capacity in this middle pressure range is high enough for
many interesting and astonishing applications. Nevertheless, as outgrown plants start to lignify
for improvement of stability, one can go a technological step further. Airlight Ldt in close
collaboration with prospective concepts ag has developed the fundamental new structural concept
called Tensairity. Tensairity is a synergetic combination of a pneumatic structure with traditional
structural elements such as cables and struts. In Tensairity, cables, struts and compressed air
complete each other perfectly. The result is a modified airbeam with the same load bearing
capacity as a steel beam, but with a substantial weight reduction. This technology is ideally suited
for wide span structures and for deployable applications such as temporary bridges, scaffolds or
large tents and opens up many new technical opportunities for pressure induced stability.

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