Forgot password

Cambered Sails & Wind Flow

  • 15 Jun 2011 13:58
    Quote
    Reply # 621910 on 618038
    Anonymous member
    Arne Kverneland wrote:

    Stavanger, Friday

                                       NL 56, paper versus web.

    Thanks Mark,

    The articles you mention are a bit dated. I would have made a couple of small corrections if I had known they were to be printed in the Newsletter. Actually these articles and some more are already stored on this website: If you click on JRA public pages and then on "Arne Kverneland’s Files", you will find them there. Could I suggest you start with "Junkrig for Beginners.pdf" ;-) ?

    As to your question about airflow over the sail; you may find "Camber, the Johanna way.pdf" worth reading. I keep a little camber in the top panels too, but only a fraction of that in the lower ones. The 3-panel top fan has proven to be a very good sail in strong winds. They are also fine in lighter winds when I want to slow down for approaching harbour or for mackerel fishing...

    Btw: The layout of my articles in the newsletter 56 clearly shows that it has been optimised for paper while I optimised the original articles for screen reading or printing on a medium quality printer: The magazine quality printed NL has better resolution than a screen or normal printout, but magazine pages are expensive so diagrams and photos are often crimped to save space. No doubt readers of NL 56 will need a magnifying glass! The ideal would therefore be to have a newsletter edited in two versions; one for printing and one for the web (more space and lower resolution call for bigger diagrams and photos).

    Arne


    Arne,

    I have have to admit not having delved into your section of the site before.  Excellent information, and everything I needed to know! 

    For a cruising rig, yours definately seems the best way to go.  Love all your tips on how to make things easier,  especially the simple way of joining panels without having to 'go through' the sewing machine,  that must have saved hours.

    Regards

    Mark
  • 10 Jun 2011 18:15
    Quote
    Reply # 618168 on 617976
    Anonymous member
    Mark,
    When I first put cambered panels in Tystie's junk sail, in 2000, David Thomas, who designed her, approved, saying "the wind likes to be told where to go". The flow in the lower part of the sail is in fact pretty well parallel to the battens, though it will be rising up over the head of the sail, so the triangular panels are still the right way to go. A horizontal head seems to be not as good as an angled head, for a number of reasons, including, as Arne says, performance when well reefed.
  • 10 Jun 2011 15:44
    Quote
    Reply # 618038 on 617976
    Anonymous member (Administrator)

    Stavanger, Friday

                                       NL 56, paper versus web.

    Thanks Mark,

    The articles you mention are a bit dated. I would have made a couple of small corrections if I had known they were to be printed in the Newsletter. Actually these articles and some more are already stored on this website: If you click on JRA public pages and then on "Arne Kverneland’s Files", you will find them there. Could I suggest you start with "Junkrig for Beginners.pdf" ;-) ?

    As to your question about airflow over the sail; you may find "Camber, the Johanna way.pdf" worth reading. I keep a little camber in the top panels too, but only a fraction of that in the lower ones. The 3-panel top fan has proved to be a very good sail in strong winds. They are also fine in lighter winds when I want to slow down for approaching harbour or for mackerel fishing...

    Btw: The layout of my articles in the newsletter 56 clearly shows that it has been optimised for paper while I optimised the original articles for screen reading or printing on a medium quality printer: The magazine quality printed NL has better resolution than a screen or normal printout, but magazine pages are expensive so diagrams and photos are often crimped to save space. No doubt readers of NL 56 will need a magnifying glass! The ideal would therefore be to have a newsletter edited in two versions; one for printing and one for the web (more space and lower resolution call for bigger diagrams and photos).

    Arne

    Last modified: 31 Jan 2022 08:52 | Anonymous member (Administrator)
  • 10 Jun 2011 13:57
    Quote
    Message # 617976
    Anonymous member

    I have much enjoyed reading Arne's article in the new Newsletter.

    Fine looking sails, large and powerfull.  It would be interesting to know how the areas compare withtheir pointy predecessors. 

    One point of interest.  Does the wind flow straight along the panels?  As I understand (ok, from my archair) is that the wind tend to flow somewhat up the sail.  If so it will be crossing panels and spoiling the flow. 

    For the top of the sail, the triangular panels surely must cut across the flow.  Do these have the same camber?

    Here's a thought.  The first modern junk, the Jester rig had very poor drive,  hence the move to the raked /  triangular top panels and fanned sails.  With shape now being created, by panels or joints,  is there something to be said for a flatter headed sail plan?

    Last modified: 10 Jun 2011 13:58 | Anonymous member
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software