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Amy C. Edmondson
A Fuller Explanation
Chapter 15, From Geodesics to Tensegrity: The Invisible Made Visible
pages 249 through 251

New Concept of Construction

That humanity can learn from the principles of nature is the essence of Fuller's message. We must abandon our building-block concept of structure in favor of comprehensive solutions which take advantage of the inherent qualities of tension and compression. The latter tends to do the local, isolated structural tasks in nature, while the former specializes in cohering systems over great distances. While we understand that Universe is not structured like a stack of bricks, that awareness has not affected our approach to construction. A "building-block" approach has persisted more or less unchanged for thousands of years, pitting structural bulk against gravity's vigilant force. Instead, argues Fuller, we must think in terms of whole systems in equilibrium, omnidirectional forces interacting in self-stabilizing patterns. If, emulating nature, structural design capitalizes on the integrity of tension, these "whole systems" will prove far stronger than analysis of their separate parts could predict.

      Additionally, we can learn from nature's structuring method: converging and diverging, she produces bubbles, explosions, stars, and the radially expanding sound and light waves. Energy pushes out, and its expansion is countered by tensional restraints such as the pull of gravity and molecular forces. Eventually, the two dynamics reach an equilibrium, a tentative balance such as a soap bubble.

      Fuller heralded an "era of thinking and conscious designing in terms of comprehensive tension and discontinuous compression" (640.42). He saw an unmistakable change taking place, largely going unnoticed. This "new era" began with the spoke wheel, which Fuller pinpoints as man's first breakthrough into tensegrity thinking:

      I saw that his structural conceptioning of the wire wheel documented his intellectual designing breakthrough into such thinking and structuring. The compressional hub of the wire wheel is clearly islanded or isolated from the compressional "atoll" comprising the rim of the wheel. The compressional islands are interpositioned in structural stability only by the tensional spokes... . This reverses the historical structural strategy of man. (640.42)

The wheel's use of tension enables a far more efficient and lightweight structure than could be produced with compression spokes. Tension materials are inherently smaller and lighter than compression materials carrying equivalent loads.

      The wheel was originally an exclusively compression structure starting with the cave man's stone cylinder and progressing to slightly more sophisticated designs like "the old artillery wheel" cited by Fuller in Synergetics. (8) It continues to be perceived as such. (A version of that wheel is sketched in Figure 15-10.) Widespread awareness of the tensional integrity responsible for the spoke wheel's lightweight efficiency has not been reached. The load on a bicycle wheel is therefore often seen as "sitting" on the lower spokes-like colurnns-rather than hanging from the top spokes. Despite design breakthroughs, humanity as a whole is still caught in "solid-things" thiriking.

Wheel with compression spokes
Fig. 15-10. Wheel with compression spokes.
Click on thumbnail for larger image.

      Many other structures that rely on tensional integrity can be cited, such as suspension bridges and sailboats. However, Fuller points out that tension was usually incorporated as a "secondary accessory of primary compressional structuring." In other words, ancient man-habitually relying on compressional continuity-inserted a "solid" mast into his hull, but finding that the wind kept blowing his mast over, he added a set of stabilizing tension wires, or slays, in nautical terminology. Somehow he failed to learn from his accidental design, in which the extraordinarily thin, lightweight tension adjuncts withstand the same forces as the heavy solid mast.

      Tension has been secondary in all man's building and compression has been primary, for he always thought of compression as solid. ... Earth and ship seemed alike, compressionally continuous. (640.50)

Modeling the Invisible

Tensional integrity is certainly how Universe works, pondered Bucky in the 1940s, but how can I illustrate this invisible phenomenon? Can the co-occurrence of discontinuous compression and continuous tension be modeled in such a way as to bring this structural principle into easy grasp? He was determined to display the invisible truths of science in a scale that can be perceived by human senses.

      Could it be done? Could discontinuous reality be modeled? Science in the twentieth century feels exempt from modelability, philosophized Bucky; ever since the isolation of the electron in 1898, scientists have felt increasingly more sure of their lack of responsibility to explain their work to the layman. The hypothetical scientist of Fuller's lectures declares, "I am sorry to say, reality is both invisible and unmodelable."

      In the summers of 1947 and 1948, Fuller taught at Black Mountain College, and spoke constantly of "tensional integrity." Universe seems to rely on continuous tension to embrace islanded compression elements, he mused; we must find a way to model this structural principle. Much to his delight, a student and later well-known sculptor, Kenneth Snelson, provided the answer. He presented his discovery to Fuller: a small structure consisting of three separated struts held rigidly in place with a few strings. This was the birth of an explosion of geometric tensegrity structures. Inspired by Snelson's discovery, Fuller went on to create tensegrity versions of countless polyhedra.

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