Subject: Re: [harryproa] Re: Timber spar
From: barrie lyall
Date: 2/25/2008, 7:50 AM

Robert , I totally agree. I think it is best however to steep the bamboo in some hydrogen peroxide to reduce the starchand proteins and then steep in a borax solution as a further preventative against rot. That is what they do for bamboo flooring (peroxide) the bamboo for house building in Hawaii (Borax).
proaconstrictor <> wrote:
--- In, "Robert" <cateran1949@...> wrote:
> Consider bamboo strips. Quality bamboo has better characteristics than
> most timbers. Check out the Youngs modulus and breaking strains of the
> bamboo used in fly rods It makes excellent fly rods. I was looking at
> making a wingmast out of bamboo, birch plywood and cedar.

Interesting idea. I have worked with bamboo a little including fly
rods and bows. The main advantage in fly rods is that it allows the
creation of rods with better accuracy in the sections than carbon,
which always has a disorganized spine, and the bamboo has better
damping. In certain situation like light dry fly rods this is a
winning combination. It sure doesn't cast a long line like carbon, and
large rods soon seem like telephone poles. Interestingly there is a
new book out by the ever innovative John Betts for timber fly rods,
apparently they work great, the only problem is that normal casting can
take them past the elastic limits of the materials, but they can work
great for short accurate work.

My recent inspiration is modern glider technology. I have always been
interested in wooden aircraft structures. I have tended to be
influenced by the structures of WWII wooden planes like the well known
Mosquito (locally built in both Canada and Australia), and the Spruce
(birch actually) Goose. I am also interested in Ultralights. Not
until recently did I start to look at sailplanes which are in a lot of
respects a more meaningful standard for comparison.

Sailplanes like yachts have heavy and light air performers. The racing
is mostly in the high speed area, but the wind velocities there are
totally out of wack with sailing speeds. Even the slowest sailplanes
top out in full gale force conditions if we were talking sea surface.
So the specialized area of high lift sailplanes offer the best

I haven't run the numbers but the three building systems, wires and
poles, cantilevered wooden tubes, and carbon tubes seem interesting in
comparison with our spar systems. Not that much performance is given
up in moving from carbon to wooden spars. Certainly significant, but
possibly not out of wack with expectations for racing vs. cruising

Most bolger spars are either solid or hollow wood. This particular
spar is directional and a plywood box section with timber spine. I
don't know that it would work, but it might, and would cost maybe 100
bucks to build at the 32 foot mark. With wood there is the further
possibility of scavenging for free.

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