Subject: Re: [harryproa] Model Beach Proa Update
From: Rick Willoughby
Date: 6/13/2013, 7:37 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

This is the second long hull and third shorter hull.  The second and third shorter hulls were both a little longer than the first.  The first one was initially set to windward.  When it was placed on the lee side it nose dived a little so made it longer to reduce that tendency.  That was before the sail was sorted.  Now that we can get the required cant angle, the lift vector is to the lee of the windward hull and forward of centre so the diving tendency has gone but the lw hull has not been changed in length.  The fourth short hull will be the same length as third.


It has taken a few iterations of the rig to get the lift vector where we wanted it.  It has already done some impressive speed.  If we get some decent wind I aim to get some video of it literally flying or near to it.  Response and balance are both very good.

On 13/06/2013, at 9:25 PM, Nick B wrote:

 

Sorry I should have been more clear. And I may be mistaken but this version it seems like the short ama is getting longer?  I thought in earlier versions it was shorter. If so just wondering about the reasons.
nick

On 2013-06-13 7:04 AM, "Rick Willoughby" <rickwill@bigpond.net.au> wrote:
 

I do not understand the reasoning behind the comment.  Almost a cat - apart from:

1,  bi-directional hulls, 
2. bi-directional sail, 
3. bi-directional rudders, 
4. hulls symmetric fore and aft,
5. two dissimilar hulls - notably the underwater portions, length, strength and weight,
6. heavily canted sail,
7. single mast stepped in one hull,
8. a rudder at either end of one hull,
9. rolls into the wind when pressed - negative heeling moment,
10.  leading bows lift when pressed - negative pitching moment,
11. boat shunts to change direction rather than tacks,
12. sail compression strut and bottom beam separate to mast,

It is different to a harryproa.  In configuration it is closer to some of John Pizzey's designs.  However takes sail canting closer to that of sail rocket using more like a kite than rigid wing. 
 
On 13/06/2013, at 7:53 PM, Nick B wrote:

 

The boat is almost a cat now.

On 2013-06-12 10:28 PM, "Rick Willoughby" <rickwill@bigpond.net.au> wrote:
 

Dean has made quite a few mods to his model proa and it is now doing what we were aiming for - leaning INTO the gusts:

http://www.youtube.com/watch?v=CxEffgLi8Mk

The rig is now more controllable and can be feathered although the model does not do this yet. 

We have not yet seen it roll back into the wind but conditions were light while testing the latest configuration.

Rick Willoughby







Rick Willoughby







Rick Willoughby




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