Rick,
Check out the wingsails forum on the Junk Rig Association website. You might have to be a member to look at it. I am and it's not expensive, and you get a nice magazine out of the deal. There's been some interesting builds over the years and they always seem to involve round masts. How's your human powered drive stuff going?
Jerry Barth
Sent from my Sprint Samsung Galaxy S7.
-------- Original message --------
From: "Rick Willoughby rickwill@bigpond.net.au [harryproa]" <harryproa@yahoogroups.com.au>
Date: 7/3/17 9:02 AM (GMT-05:00)
To: harryproa@yahoogroups.com.au
Subject: Re: : Re: [harryproa] kite boat systems
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: shredderf16 <shredderf16@sbcglobal.net>
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