Yes controlling leading edge along with trailing edge and seeing the correlation between sheet angle and wind angle from leading edge to trailing edge the dyna rig or similar has a lot to offer on a proa or shunting craft, I think.

As I see it depowering is gain a hang up in only the philosophy of sailing something new. Why wouldn't the sail depower?

Maltese Falcon has no problem with capsize and it has three dyna rigs. A hybrid of the three sails combined JR, Dyna, and, Wing might just be the ticket to over come some of the complexities that are built into the way the Maltese handles its own sails. Which is exactly what I'm try to build an alternative way in which to control the rig. Sheetlets, center pivoting, single skin, full battened, and reef ability. Combinging the three to four types of sails that I have experimented with from so far.

Todd

--- In harryproa@yahoogroups.com.au, Arto Hakkarainen <ahakkara@...> wrote:
>
> The fatter leading edge should be more forgiving. Sheeting from the leading edge is quite possible and obviously needed to make dynarig perform well. I still don't like the idea of not being able to automatically depower the rig if we are talking about bigger size boats where capsize is an issue.
>  
> Arto
>
> --- On Fri, 6/11/10, tsstproa <bitme1234@...> wrote:
>
>
> From: tsstproa <bitme1234@...>
> Subject: [harryproa] Re: Predicting performance?
> To: harryproa@yahoogroups.com.au
> Date: Friday, June 11, 2010, 3:49 AM
>
>
>  
>
>
>
>
> I think from memory that the claw was 65 or 70 and the dyna 80 sq inches. Funny the solid wing design in blue foam has a fatter leading edge than the claw with its narrow carbon spar. Solid wing design does seem more forgiving. But I have to disagree with you on the dyna or solid wing being sensitive. Once the drive angle is found its pretty much set, if you move it around, searching for it you will stall the sail/wing. The wing and dyna are rotated off front leading edge vs trailing edge very different theory in general sailing principal closer to kite surfing I think. This is what I was getting at from the very beginning. My junk is just the stepping stone in proving my theory of such, being center chord cambered and fore end sheet capable just a small step-baby step to the goal.
>
> Todd
>
> --- In harryproa@yahoogroups.com.au, Arto Hakkarainen <ahakkara@> wrote:
> >
> > Yes, I noticed the sheeting angles. It proves what I had thought in theory that the dynarig with very sharp luff should be able to sail very well to weather if it is a high aspect sail. Also it proves that such sails with sharp luff are quite sensitive to the correct angle to wind to get the best performance out of the sail. In many ways it should behave similarily to jib with also sharp luff. Maintaining luff tension could be an issue in bigger size sails.
> >  
> > The dynarig seemed taller and bigger. Was there a big difference in sail areas? bigger and taller should perform better of course. Luff length is important to windward performance.
> >  
> > Arto
> >
> > --- On Thu, 6/10/10, tsstproa <bitme1234@> wrote:
> >
> >
> > From: tsstproa <bitme1234@>
> > Subject: [harryproa] Re: Predicting performance?
> > To: harryproa@yahoogroups.com.au
> > Date: Thursday, June 10, 2010, 8:51 PM
> >
> >
> >  
> >
> >
> >
> > In regards to aoa to wind did you see the sheeting angle of both sails. Neither one was sheeted in hard to center line of boat like most would associated windward work to be yet both sailed very high to windward with out sheet adjustments. At the beginning of the clip leading and trailing edge of both sails. Both are almost parallel to the wind while they start out sailing a close reach all the way up to a close hull almost directly into the wind the sheeting angle never changes. The clip is unedited that's one continuous clip nonstop. This clearly shows the configuration of each sails sheeting angle and there ability for windward work with out sheet sail to center line of boat. Both sails capturing the apparent wind bubble maintaining foward drive without closing the gap like on most traditional western sailing craft loop rigged. Wouldn't you agree?
> >
> > Todd
> >
> > > > --- In harryproa@yahoogroups.com.au, Arto Hakkarainen <ahakkara@> wrote:
> > >
> > > > > Arto:
> > > > >
> > > > > Do you have any idea what the AoA of the wind to the sail would be? Theoretically and based on old experience the sail should have CoE forward of mast when the flow is attached to the sail. Then the sail would need to be sheeted from forward. If stalled the CoE probably moves closer to the mast. Some videos you sent and your own description would back this theory. I might as well be wrong guessing here at my comfy chair :)
> >
> > --- In harryproa@yahoogroups.com.au, Arto Hakkarainen <ahakkara@> wrote:
> > >
> > > Todd,
> > >  
> > > It took some thinking before I got it. Also a bit hard to tell since puffs are not that easy to see on the video. My analysis:
> > >  
> > > Dyna rig is more sensitive to correct angle to wind than traditional crab claw. Airflow must remain attached to the lee side of the sail to get the best lift. In the beginning dynarig moves slowly so I guess the sail is too hard on the wind and stalled. At the end when it turns upwind dynarig accelerates and starts moving very fast. Based on what you said about wind direction it probably had good wind angle to sail and looked like having a lot of power at the end of the video.
> > >  
> > > Traditional sail that looked like crab claw is a different animal. Based on the wind tunnel tests by Marchaj it is not sensitive to correct angle to the wind and has best lift coefficient when the flow is not attached any more and the sail is generating vortexes. Also according to the same tests crab claw is not at its best close hauled. In the beginning of the video traditional crab claw moves the boat very fast on a reach and tight sail but less so at the end when the boat turns to wind. It seems like you just proved the Marchaj wind tunnel tests :) At least your two rigs side by side acted in accordance with the results of Marchaj.
> > >  
> > > Arto
> > >
> > > --- On Wed, 6/9/10, tsstproa <bitme1234@> wrote:
> > >
> > >
> > > From: tsstproa <bitme1234@>
> > > Subject: [harryproa] Re: Predicting performance?
> > > To: harryproa@yahoogroups.com.au
> > > Date: Wednesday, June 9, 2010, 8:08 PM
> > >
> > >
> > >  
> > >
> > >
> > >
> > >
> > > Arto. Words get tricky to me. I know What I'm tring to accomplish and know the feel i'm searching for. Sounds hokey I know. Thanks for bearing with me though.
> > >
> > > As far a sheet angle and wind wangle look at this clip . wind is coming from about upper left had corner. Look at both trailing edges of each sail. Look at the leading edge of dyna rig. Watch as each boat gathers speed and there reaction to puffs. Look at the finishing angle as both as they approach the beach at end of clip.
> > >
> > > http://www.youtube.com/watch?v=s-AzmNEj0EE&feature=related
> > >
> > > Whats your explanation?
> > >
> > > Todd
> > >
> > > > --- In harryproa@yahoogroups.com.au, Arto Hakkarainen <ahakkara@> wrote:
> > >
> > > > > Arto:
> > > > >
> > > > > Do you have any idea what the AoA of the wind to the sail would be? Theoretically and based on old experience the sail should have CoE forward of mast when the flow is attached to the sail. Then the sail would need to be sheeted from forward. If stalled the CoE probably moves closer to the mast. Some videos you sent and your own description would back this theory. I might as well be wrong guessing here at my comfy chair :)
> > > >
> > > > ++++++Not a clue. On the rigid wing the leading edge at times seems straight into the wind on my JR I have seen it guesstimate 15-20 degrees to the wind. I think on my JR this is due to the camber not being as large and efficiently shaped being shape in the cloth vs becambered held by battens or a preshaped wing. The CoE of sail is foward yes and the CoE can be controlled precisely. Its the configuration of the sail that allows the sheeting arrangement along with its rigid camber at center chord and the whole sail rotating when sheeted that provides its uniqueness.
> > > >
> > > > Todd
> > >
> > > > > Arto
> > > > >
> > > >
> > >
> >
>

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