Tystie's rig - the 2015 model

<< First  < Prev   1   2   3   4   5   ...   Next >  Last >> 
  • 29 Jun 2015 23:55
    Reply # 3409110 on 3302473
    Deleted user

    After reading the entries on this topic I feel as though I have just completed the class:  Junk rig hinge battens 101.  Very interesting.  So there is an alternative to camber sails.  It seems like a neat solution to adding camber to flat sails.  

  • 24 Jun 2015 16:40
    Reply # 3402254 on 3302473

    David, how does your split sheet system look like? It's not apparent from any of the pictures I've seen. Is it based on something in PJR? There are three examples in there but they're all with six sheeting points instead of eight.

  • 21 Jun 2015 19:24
    Reply # 3397428 on 3302473

    Darren,

    I like it. I imagine a soft leading edge will work, at least better than nothing at all. I'm attracted to the wing myself mainly due to the chance to get good balance and reduced sheeting loads. I'm an airline pilot so I see every day the big effects being able to change the camber in a big way really makes a difference. Given the speed range we're talking about is small, but it would be fun to experiment. Then the practical side of me thinks it isn't worth the trouble. I've been following soft wings for years in various places and I've never seen anyone get closer to the holy grail of simple and good performance than the people on this forum. I wish I could go in my shop and start making models but my wife would kill me as I haven't yet finished her dream bathroom. Please keep up the good work. I'll have to think about the wisbone torqueing problem you described.

    Cheers,

    Jerry Barth

  • 21 Jun 2015 01:09
    Reply # 3397077 on 3302473
    Deleted user

    Hi Jerry, 

    The design I'm going to pursue is more like a gaff jaw on the front of a hinged batten.  The front part of the airfoil is then attached forward of the jaw.   You can see a pic here:

    http://www.junkrigassociation.org/page-1401723/41430468

    David's wishbones were very nice in that they provided structure to shape the front of the airfoil all the way aft to the hinge.  However, I think their width contributed to their failure.  When the sail begins to fan up it can twist the wishbone, and the wider the wishbone the wider the lever arm for the sail to exert a twisting force on the nose.  Since the nose of the wishbone is prevented from twisting by the mast, eventually something breaks.  In David's case this was confounded by the vertical hinge movement which exacerbated the whole thing.  

    When David suggested the arrangement shown in the link I liked the fact that there are very few ways for the sail to impose a twisting movement on the batten.  Further, the design is very similar to the jaw on a gaff rig which is well understood and provides a guide to the design requirements.  This version doesn't have a rigid structure to determine the shape of the cloth once it is past the mast, but most sails don't either. 

    I'd have to spend some more time thinking about the design you propose, it does provide a way a making a nice airfoil shape.  The best design will likely have relatively few moving parts.  Every axis of movement provides another way for things to get messed up.  

    Last modified: 21 Jun 2015 18:29 | Deleted user
  • 20 Jun 2015 21:17
    Reply # 3396990 on 3302473

    Darren,

    Excellent video I really think your hinges are going to work. Are you planning on the long wishbone nose like David tried? One thing I thought of making them a long u shape like David did. On the rear of this you tie the ends together with a steel pin/tube kind of like the aerojunk. Then you take one of your hinges, cut it in half, and where the hole in the middle of the hinge is thread it on the steel tube at end of nosepiece. The hinge can now slide side to side at the back of the nosepiece. Next attach short length of batten to this sliding hinge, then from there aft another hinge with basically David's new sailplan after that. Now if we can figure out how to control the nose I think we'd have a very nicely shaped wing. I've got all the tools, unfortunately my wife's new bathroom and a full time job are holding me back. I love the innovation going on here, you guys are great!

    Jerry Barth

  • 19 Jun 2015 00:05
    Reply # 3392430 on 3376344
    dennis gibbons wrote:

    David,(or anybody else)

    Any thoughts abut using Delrin (or other plastic) for the hinge?

    It is lighter and stronger than wood but  can also be machined or turned on a lathe if one were to use round battens.

    Would it be too flexible ?


    Dennis

    Of the engineering plastics, I would use solid PVC bar - tough, low cost, and quite strong enough. All the engineering plastics are heavier than wood, but that's not really significant here.
  • 08 Jun 2015 05:15
    Reply # 3378652 on 3302473
    Deleted user

    Hi Mark, 

    I must do a poor job of explaining the hinge, because it is not that complex.  With the hope that a video is worth a thousand words, I have made my first youtube video ever (my apologies for the video quality).  I forgot to say in the video that the holes in the aluminum tube that pass the line will probably need something to reduce chafe that has yet to be determined.  The video is at:

    https://youtu.be/gusYdEuSSz8

  • 06 Jun 2015 09:38
    Reply # 3377223 on 3302473

    Darren,

    Hinge look well engineered, but I cannot fully understand how it works?

    Cheers


  • 06 Jun 2015 09:37
    Reply # 3377222 on 3302473

    Darren,

    Hinge look well engineered, but I cannot fully understand how it works?

    Cheers


  • 06 Jun 2015 04:14
    Reply # 3377119 on 3302473
    Deleted user

    For comparison the polyurethane I was using has the following traits:

    Shore D hardness: 85

    Tensile Modululs: 370 000 PSI (2.55 GPa)

    Ultimate Tensile: 7800 PSI (54 MPa)

    This is the polyurethane resin I was able to get locally.  One of the interesting parts of moulding in polyurethane is there is a great variety and you can select just about whatever traits you like.  For my production run I was considering the below polyurethane:

    IE 3075

    Shore D hardness: 80

    Tensile Modulus: 420 000 PSI (2.90 GPa)

    Ultimate Tensile: 10 500 PSI (72 MPa)

    I've used tensile modulus for consistency with Dennis, and the fact that for the plastics we're considering the tensile modulus usually close to the flexural modulus.  However,  I think flexural modulus is probably the more important number for hinge consideration.

    It looks like the ultimate tensile of Oak is somewhere between 50 and 100 MPa.

    Polycarbonate has a shore D hardness around 80.

    For both polycarbonate and polyurethane you could use fibre reinforced versions to get even better numbers, but that may not be necessary or worth the extra trouble.



<< First  < Prev   1   2   3   4   5   ...   Next >  Last >> 
       " ...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