Tim Tyler wrote:
Greetings, fellow urglers ;-)
I've made a page about triaxial polytunnels.
In particular I've created the following pages:
Triaxial index : http://hexdome.com/triaxial/
Weaving : http://hexdome.com/triaxial/weaving/
Polytunnel : http://hexdome.com/triaxial/polytunnel/
Sphere : http://hexdome.com/triaxial/sphere/
It's probably best to start on the first link.
The material about polytunnels is what's likely to
be of interest to the denizens that inhabit this group.
Basically, I built a model of a triaxial weave
polytunnel, photographed it, wrote some material
about its significance - and then uploaded the results.
To quote from the introductory paragraph:
``Farmers do not need the wide spans and high spaces domes
offer - for them, polytunnels make much more sense.
I looked at conventional polytunnel designs. As far as I can
see they make little structural sense. Their structural
elements often rise straight into the air with little sign
of support. As a result the designs often have to rely on
the use of excessively rigid (and expensive) materials -
and braces.
Polytunnels represent an /excellent/ case for using triaxial
weaving. Triaxial weave is light, resiliant, strong in all
directions, /very/ resistant to shearing forces - and yet
still easy to construct.''
As I go on to argue:
``For a given strength, an intelligent structural design
allows substantially lighter (and cheaper) materials to be
used. In particular, polytunnels of reasonable size can be
constructed along these lines using PVC conduit - which is
an astonishingly inexpensive material. [...]
Polytunnels facilitate growing sensitive, tropical
fruiting plants in northern climes - where much of the
planet's landmass and population reside.''
Thus, I consider polytunnels to have significant economic
importance.
It's my hope that I can contribute to making many of them
cheaper.
OK: that makes structural sense, given cheap enough materials. But
have you put _time_ into your calculations?
Mike.