Hi David,
a few layman comments / queries re your wingmast sketches.
I am really surprised the wingmast only has to rotate 30 degrees. So the wing mast is only rotated 15 degrees from being completely horizontal to the direction of travel!? The wing mast - soft wing sail combination seems to work out well for a proa. One benefit: the mast does not need to be free-standing, it can be stayed?
The jpeg shows detail of the wing mast. The boom is presumably truncated, compared to pdf image? The boom appears to project inside the mast and angle of rotation is limited by walls of mast? But this angle is less than that in the pdf image(s)?
The pdf image shows a nice foil-like curve to the sail. Will sail-cut be used to create this curve?
cheers Dave
--- In harryproa@yahoogroups.com.au, "david_tyler_sv_tystie" <tystie34@...> wrote:
>
> My wingmast sketch is in the file section now, along with a section through my soft wing based on Wortmann fx77w153.
> Note that the wingmast only has to rotate through 30 degrees between shunts, and that if it is controlled within those limits, the mast/sail combination can remain properly aligned up to 60 degrees of apparent wind, which ought to be enough.
> Wide, thin wingmasts are distinctly unfriendly on a cruising boat - they will not stop sailing when the boat is anchored or moored. My sketch shows a wingmast as narrow and as thick as it can be, to minimise this effect, whilst still being fully effective in use.
>
> --- In harryproa@yahoogroups.com.au, "David" <dave.pont@> wrote:
> >
> > Hi David,
> > thanks for the informative reply, and I look forward to seeing your sketch, this sounds very interesting...
> >
> > regards Dave
> >
> > --- In harryproa@yahoogroups.com.au, "david_tyler_sv_tystie" <tystie34@> wrote:
> > >
> > > This is the prime source of foil data, from which all others seem to quote:
> > > www.ae.illinois.edu/m-selig
> > >
> > > but from sources such as this, you can get a foil drawn out for you:
> > > http://www.windandwet.com/windturbine/airfoil_plotter/index.php
> > >
> > > and here you can get .dxf files, which you need to be able to design a rig:
> > > http://isoar.ca/~andrewm/rc/airfoils/19.html
> > > If you haven't already got 2D CAD, I recommend QCAD from www.ribbonsoft.com - a very good package for very little money. I couldn't design wingsails without it.
> > >
> > > These people seem to favour UI1720, a good foil for double-skinned hanggliders and microlights, which I would use, if I could figure out a way to make a soft wingsail with it, but I can't:
> > > http://groups.yahoo.com/group/Airchairgroup/message/9522?threaded=1&p=9
> > > and E1210 is also mentioned. That is a "General Aviation Foil" intended, I think, for low speed aircraft, operating in a very similar Re regime to a fast proa.
> > >
> > > I stick with my Wortmann fx77w153 foil as being the most suitable for a soft wing.
> > >
> > > Gardner has been discussing my soft wingsails with me elsewhere, and I am coming to the conclusion that a soft leading edge is not the way to go, for a fast craft operating with the apparent wind very far forward. It's right for me, with a heavy monohull, but not for a proa. I think that high speed sailing demands a hard, smooth start to the section, at least for the first 10%, ie a wing mast. I'm going to put a sketch of what I would do for a proa, based on E1210, in a folder in the files section, under my name.
> > > David.
> > >
> >
>