Hexagonal Geodesic Domes

Pentagonal prism tensegrity

Here's a "floating strut" tensegrity.

Pentagonal prism

Note that the struts do not touch each other.

It is an unusual structure - since it contains no triangles.


Some people seem to think that structures are necessarily dependent on the presence of triangles.

They sometimes cite Buckminster Fuller on the issue:

"Only the triangle produces structure and structure means only triangle; and visa versa"

 - Synergetics, 608.05.

"By structure we mean omnitriangulated.  The triangle is the only structure."

 - Synergetics, 610.02.
"If we want to have a structure, we have to have triangles."

 - Synergetics, 610.12.

However, no coherent explanation of why this might be so appears to have been offered. At one point he says:

"we have learned experimentally that only triangles are stable"

 - Synergetics, 401.03.

Structures like this one appear to represent experimental counter-examples to the notion that stability depends on the presence of triangles.

The apparent stability of this totally triangle-free configuration surely casts serious doubt on the dogma that triangles necessarily form the basis of all stable structures.


That this structure appears to be stable makes it a good example of structural synergy.

It's also of interest since each strut is attached at each end to three cables - the minimum possible for a "floating-strut" tensegrity.

This is the simplest model with these properties that has been found - though it may be possible for a similar four-strut system to be constructed.

Pentagonal prism


Pandia Raj Ramar's pentagonal model

Adrian Rossitor's hexagonal model

Bob Burkhardt's hexagonal model

T-Chime pentagonal model - probably a different cable configuration

Tim Tyler | Contact | http://hexdome.com/