Luc
I have been asked to assess a bi-directional sail similar in shape to those in use on Maltese Falcon for the 18m proa:
I have played around with something similar on a model proa that was tremendously simple to shunt:
The aim is to have a sail that is easier to shunt than swinging the Aerorig through the required 160 degrees or so when working upwind. A bi-directional sail reverses simply by changing angle by 20 to 30 degrees when going upwind. One constraint is the existing round mast. I expect that will require some form of soft fairing to reduce the drag. An essential requirement that requires some evaluation is ability to quickly de-power in a gust.
This is a project that will be evaluated at model scale for the next few months.
Rick
On 3 Jul 2017, at 10:45 pm, lucjdekeyser@telenet.be [harryproa] <harryproa@yahoogroups.com.au> wrote:Thank you Rick and Rob. This was very informative. The smooth contours of the comparative polar diagram I had found on the web site earlier suggest it was generated more by wishful thinking than by actual data points. In hindsight I am reminded again that there are no loopholes in physics. I had hoped it would have been enough to adapt current drone control systems to a tethered kite. My attention is back to the promise of the simplicity of mast laced mainsails ;-)
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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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