<<If you use a flexible batten only, it will be too stiff in
light airs
and too bent in heavy winds - the opposite to the requirement. In
addition a flexible batten may bend the wrong way forward of the mast
and finish up as an S-shape.>>
Right. The front wishbone almost certainly needs to be a two-sided
rigid or semi-rigid frame in order to keep that nice leading edge,
which is the most important part of the whole rig, as well to support
the sail in front of the mast. A single skin could still generate a
lot of lift if it had the right shape, but a single batten will never
develop the proper curve forward of the mast.
The question is what to do aft of the aft end of the wishbone. The
second wishbone creates a beautiful shape, but in the process uses even
more material aloft. A flexible batten on a hinge, instead of the
wishbone, should be lighter and almost as efficient. It's the first
third or first half of the sail that is most important.
On the other hand, in lighter wind, you'd probably want more curve to
the sail, which is when a batten would have the least curve.
I just want a magical rig with a perfect shape without so much
framework aloft.
One thought I had was to use the same type of inflatable battens that
are found in single-skin kiteboarding kites. They manage to provide
quite a bit of support with very little weight (which is one reason why
they don't use wood, glass, or carbon fiber).
The trick would be to make sure the bladders are surrounded by more
than one layer of UV-resistant material like spectra/dyneema. As long
as light doesn't get to them, they should last indefinitely.
- Mike
John wrote:
When trying to use a flexible batten you are back into the problems that people like the Junk Rig Association have been tackling for years. The most used variation is to have a hinged batten (stiff batten, limited movement hinge in the middle).
If you use a flexible batten only, it will be too stiff in light airs and too bent in heavy winds - the opposite to the requirement. In addition a flexible batten may bend the wrong way forward of the mast and finish up as an S-shape.
--- In harryproa@yahoogroups.com.au , "robert" <cateran1949@...> wrote:
>
>
> I had a good look at the site and I am quite impressed. The sail shape is very nice. I am not sure why the curve couldn't be done with a flexible batten.
> --- In harryproa@yahoogroups.com.au , Mike Crawford <jmichael@> wrote: