15 – The Three Kinds Of Tension Lines

A tensegrity structure’s tension network is external to the compression struts and although the tension system controls the structure as a total skin each separate line connecting point-to-point exerts its control in a specific way.

“Edge” tension lines define the edges and the sides of each module. The three-way column has three edge lines for each module. In most cases, edges carry less tension than draw or sling lines.

“Draw” tension lines pull the modules toward one another. In the three-way column, each module is connected to each neighbor by three ascending draws and three descending draw lines.
“Sling” tension lines suspend the modules, performing like the slings used in rigging work. They connect one module to the next and are generally in opposition to the draw lines. In a three-way column six slings are required in order to link two modules.

Above is a three-way module. In this simple figure all tension lines can be called edges: six end-edges and three side-edges. They define, roughly, a triangular prism. When viewed through the vertical axis the module has a left-rotation helix. The opposite is true when viewed from the side: the struts relate to one another in a clockwise or right-rotation helix.

Right

helix

Left

helix

Right

helix

Three module, three-way column