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Mix of Poppy and Ping Pong

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  • 27 Feb 2011 18:10
    Quote
    Reply # 534008 on 533615
    Anonymous member

    Hi Jef

    Your idea of fitting a split rig to your Proa sounds interesting. The split rig was conceived to be a very simple rig, once the shape has been sewn into the sails. Since building it I now understand that 33% sail area in front of the mast is just about the maximum balance to still be stable, so you seem to have the right idea there. I used a very simple planform and wonder if you might actually lose out by planning an elliptical planform, and give yourself more work when building it. I chose my planform to give the yard angle to push the tip vortex as far up as possible.

     

    Splitting the battens around the mast sounds quite complicated compared to simple straight battens, and I have found that my new combined batten parrel/ downhauls simplify the rig.

     

    The gap between the sails does not have to be very wide, but the cambered shape of the jib is the important one to get right. I used a modified shelf foot idea to put the camber in the jibs, but they also have what I call a sheeting angle designed in. The leeches are slack and allow the air to flow round the mast. The jib design is the key to the rig, and I have just completed a modification which I will test soon and hope it will be better than my first attempt.

    I only used about 6% camber in the ‘main’ sail panels as it is the jib angle and camber that does the real work. The main panels just augment the flow over the jibs.

    I plan to have a complete write up of it this year, but am spending too much time on other less productive activities at the moment.

    Cheers

    Slieve
  • 26 Feb 2011 18:46
    Quote
    Message # 533615
    Deleted user

    Since short I am one of the new members and have the intention to change the BM rig of my 15ft tacking Proa into a split junkrig.My interest in junkrigs awaked reading an article in the AYRS journal about "Poppy"followed by "building your own junkrig" by Derek van Loan and a search on the internet where I found the "JRA " and the Proa "Ping Pong".

    I have my Proa on a trailer and want to keep it as light and simple as possible,because at my age of 71 it becomes quickly to tiring. My Proa has a lot of sail and is very fast, but ask also a lot of effort to sail and I hope to make it easier with a junkrig.

    Comparing "Poppy" and "Ping Pong" i came to the following idea.                                   

    1. Make the battens 16x14mm aluminium tubes. SA. 11m2,6panels,panelheight 66cm.33percent of the sail forward of the mast.

    2. Using an eliptical planform like "Ping Pong"to have all the battens in a horizontal plane.

    3.Cut the battens where they touch the mast and reconnect them with a carbon clip in the form of 2 omega's. They swing  round the mast, and I can avoid hongkong and batten parrels.

    4.Split the rig like on "Poppy".

    I have in mind to make the sail from spinacker cloth "Mirai",weight 48gr/m2 and give the panels of the after part a camber of 8 percent of the chord.

    I wonder how much gap there must be, between the mast and the leech of the forepart and the mast and the luff of the afterpart?

    To prevent the wind from the forepart blows against the mast,there must be enough camber in the fore part. But how much?

    Is it better to makein the forepart a shelf along each batten in the form of an Nacra 18 profile, and have  the chord of the Nacra profile at an angle with the batten of say 11degrees?

    I have no experience witht a junkrig and hope some body can tell me where i go wrong.

    Jef Verhaar.

     

     
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