Figure 8: Minimum of Twelve Spokes Oppose Torque: Universal Joint
It takes a minimum of 12 spokes to overcome the turbining evident
with the minimum four vectors of restraint. This is demonstrated with
the 12-spoke wire wheel with its six positive diaphragm and six
negative diaphragm of which respectively three each are positively
and negatively opposed turbining or torque members.
Two-axis "universal joints," analogous to the wire wheel as a
basic principle relying on the independent differentiation of tension
and compression for its effectiveness. These all may be considered
basic tensegrity systems.
[Editor's note: The entry for "C" is omitted in the letter, though
the initial "C." appears. In Fig. 6.61 of Cosmography,
the caption for this
item reads: "A strong tensional web, fabric, rubber, or leather disk
may serve as a continuous tensional sheet between the opposed turbining
or torque members." Fig. 6.61 omits the far left figure and
the next to the right figure is elaborated with more components.]
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Copyright 1999, Estate of Buckminster Fuller, all rights reserved.