From: J. Michael Rowland (rowley_at_quepaso.net)
Date: 03/23/00
Message-Id: <200003231708.LAA26326@mail.telalink.net> Subject: Re: Double-wall skin Date: Thu, 23 Mar 00 10:50:24 -0600 From: "J. Michael Rowland" <rowley_at_quepaso.net>
Charles J Knight wrote:
> Wouldn't that, essentially, be just reinforcing the
> form with its dual? Icosahedron and dodecahedron,
> for example... one would reinforce the other.
I haven't fully visualized it, but yes, I think it would.
> ...and it would result in a fairly lightweight system.
>
> I remember something similar in a graphic on the web.
> ... a 3F icosa ... the pent and hex panels were assembled
> similarly to bicycle wheels. A single rigid "axle"
> connected to the rigid pent and hex rings, with high
> strength cable...which produced panels that could be
> connected together into a continuous dome.
Yes! that's it. (Bucky, too, used the bicycle wheel example in describing
the minimum number of vectors interacting to limit movement.
> Something similar could easily be done with tensile
> membranes. Radial tent structures could connect between
> the "axle" and the tension ring, resulting in a double
> walled panel. Leave it empty, and you have a dead air
> space. Fill it with aerogel or some other insulation,
> and you have a useful insulative panel.
>
> It'd be pretty easy to manufacture, too... Connect the
> "axles" together with tension cables, and it'd also be
> pretty easy to reinforce.
And very lightweight. I think what we're describing is essentially a
tensegrity, although in all the tensegrities I've ever seen, the struts
are aligned along the dome skin instead of perpendicular to the skin
(which is the way I picture "bicycle axles").
This is a slightly different topic, but your aerogel comment, above,
reminded me of it: In response to a thread on the DomeHome list, I did
some drawings of a lightweight girder to replace "conventional" wooden
studs in dome construction. I was just trying to make something better
for do-it-yourself dome construction than conventional studs, but I ended
up with something that is essentially hollow and can be filled with foam
or aerogel. The drawings are at:
http://www.looknfeel.com/~rowley/images/strud.gif
Is anybody making something like this already? ...and if so, how much do
they cost?
jmr
