Hi Ray,
understood, but what about a little hook passing trough a small window ?
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Cheers
Claudio
Perhaps, RAY - this will provide more ideas. ? 
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As noted earlier, one of our “Esteemed” was directly involved in the Canada entry/winner of C Class challenge. Magnus Clark had provided me with this construction photo of a wing he was building. I believe it is based on one of the wing designs for their cat.
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Ray - here is a drawing someone provided me for my plans to build a solid wing. Profile was based on the short, stubby WILD TURKEY design.
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Another idea from a Spanish plan for a Mini40 and you can see both shrouds and forestay end on leading edge of the mast. Mast step is set back slightly from leading edge, so entire mast will rotate on the central axis (rotation aligned) and the leading edge, when rotating will simply describe a small arc of travel. Again, - can’t use a backstay or it will prevent rotation.
Dick
Claudio, I think your approach is placing a lot of bending load on a small strut and adds unnecessary complication.
using a hook in a hole at the top of the forestay is simple and well established.
Ray
Hey, I’ve just noticed that my status has been elevated to ‘Senior’ - am I allowed to be cumudgeonly now?
Ray
Ray ,
a typical swing rig for a Class M composed of carbon tubes of 14, 12 and 10mm , do not use any shroud or spreaders, just a pole free to turn inside the Hull tube via bearings.
Cheers
Claudio
Claudio, yes, I agree about the carbon mast on an M without shrouds etc. but that wasn’t what I was commenting on - you’re looking to put something akin to a rotating jumper strut and then attach the load of the forestay at the end of it - i.e. at the end of a negative lever.
Ray
I “thought” you were ! 
That’s what I get for “thinking” - so it’s time to say welcome and thanks for your on-going participation.
Claudio, I’ve been thinking further on your suggestion in post #21…
Your diagram suggests that you would use a carbon tube as the main structural element of the design. I assume that to keep weight reasonable the aerofoil section would be achieved with a light fairing, which itself will have little strength. If my understanding is correct then your pivoted strut to supporrt the forestay will act in a similar way to a backstay crane and by tensioning the forestay you might introduce some forward curve into the mast, assuming the strut is sufficiently strong. If you had a backstay too then you could end up with an S shaped top to your mast and I’m not sure how you would manage the affect on the soft sail section of the rig.
I thought a lot about using a carbon tube as the main structural member of the mast but I think an essentially monocoque approach is better, i.e. the skin of the aerofoil is also where it derives its strength, and is also essential if the battens are to be able to ‘flop’ over as the rig tacks. My thinking is to use a wing mast around 100mm chord, which will probably give a thickness of around 25mm. In the fore and aft plain such a mast, suitably moulded, will be very stiff but in the sideways plain will be less so (take a 1 metre measuring stick and try to bend it along its thick side and its thin side). However, it is possible to modify the design to introduce a lot more sideways stiffness by introducing a sheer web across the inside of the mast, creating a section like that in the attachment.
The question is how to then make such a moulding…
Ray
My approach to making a monocoque wingmast as described previously is to break it down into two sections, the leading edge (about a third of the chord) and the trailing edge (the other two thirds). See the attachment labelled ‘Wing Mast - Xsection2’
I would get blue foam cores hot-wire cut for each section. The leading edge would form the main structural member and I would laminate it with a layer of bi-axial carbon sock and a layer of unidirectional carbon sock. I would laminate the trailing edge section with a single layer of 200gm carbon cloth and then I would assemble the two halves together and apply another layer of 200gm cloth over the assembled sections. If you refer again to ‘Wing Mast - Xsection2’ you’ll see that the front section has a semi-circular hollow and the rear section a semi-circular bump on the front - this is how I would ensure accurate alignment of the two sections. I think that for optimum strength it would be best to do all the laminating and asembly in one go and vacuum bag it whilst curing - obviously easier said than done and the devil is in the detail as you have to allow for different thicknesses of laminate etc in order to achieve a smooth wing section.
There is one variation on the general approach and that is illustrated in the attachment ‘Wing Mast - Xsection3’, where both sections have semi-circular hollows and this is to allow for the incorporation of a carbon tube to take the pivot bearings on the bottom 20cm or so of the mast. Again, the devil is in the detail if you want a raked mast but a vertical pivot…
After a suitable curing period I would probably reduce the weight by dissolving out the blue foam.
'tis late here now and sleep beckons…
Ray
Sorry I missed something from my last post…
In order to stiffen the hollow trailing edge section I will add some ribs (probably laser cut ply) close to the points at which the battens locate.
Ray
Ray,
Interesting design to follow.
It will bring me back to 4 years ago when I started this discussion : http://www.rcsailing.net/forum1/showthread.php?t=3184
The projet was abbandoned before starting cutting metals, too busy in other applications, probably is time to reconsider the question.
I will watch your progress first !!!
Ciao
Claudio
Claudio, thanks. I came across this material previously when I started to look into wingmasts and wingsails for model boats and I found the material interesting and useful.
In reality, my work on wingmasts and wingsails is limited to AutoCad at present and, to be honest, I’ve not decided which to go for yet.
The main problem with a solid wingsail that I can see, apart from keeping it strong but light, is the pivot between the leading and trailing edge sections, but I have some ideas on that and I’ll share them when I can produce some sketches.
Ray
Ray,
for me the concept is limited because it shall obbey the Rules of the AC120 and class M.
For the AC120 I can still develops some ideas, while for the M I’m rather limited to a possible floppy Main only.
For the next AC33 I have still to think , actually I play with colors :
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Cheers
Claudio
Attached below is a diagram illustrating my thinking on a solid wingsail.
For construction I would probably mould the area drawn in red lines in carbon fibre and build the rest like a model plane wing, ply ribs etc. covered with one of the specialist lightweigh wing coverings.
I’ll post a larger image of the pivot arrangement and explain it further in a follow on post.
Ray
An interesting observation…
Out of interest, I superimposed the wingmast profile from earlier posts onto the pivoted wing sail profile in my previous post and they almost match along the ‘upper’ surface of the aero section.
The profile in the wingsail is based on a NACA0015 (in fact in its unpivoted state it is a NACA0015). If I used a NACA 0012 I think it would be just about the same.
The wingmast profile is based on the Clarke Y, as per the article I posted a link to.
Ray
Good morning guys (at least it is here)
I found another set of sketches that I did, and then I had made a 7" tall working model and it seemed to work fine. Disregard the profile, as I was explaining my ideas to a friend at work, but the view looking down is how I set it up. Of course, it was designed for part of a two channel system, so the actual maximum camber was set manually before leaving shore. I had it mounted on a small rod stuck into the ground in backyard to see how well it tacked - no problem at all. The second drawing is just a close up for better view. Hopefully it will give you some ideas on how to improve.
I just simulated the upper part of the Mast rotating fairing. Cord 40mm - 2 layers of 100g/m² glass, probably 80g/m² could be better ! I will try …
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Claudio
Hi Claudio -
you are on the right track there. In fact, if you extended the front fairing a bit further back, you would be similar to the sails on a sailboard. They incorporate full length battens and the batten have a “Y” shape to press against the mast, this allows them to rotate from side to side and for the batten to “pop” over to the leeward side of the sail.
No sure you would need the complexity (or weight) of the copper rings.
You could also form a wing mast much like some of the guys do/did for full size boat. Basically a leading edge solid balsa “blocK” from an aircraft leading edge wing profile. Attach a balsa sheet (or fiberglass) to each side at the desired angle. Then after the glue cures, bend the trailing edges together. You could incorporate your idea of a slotted carbon tube for trailing edge sail track.
I have attached a sketch to better explain this building technique. As noted, a good friend built a 30 foot (approx 10 meter) mast in his basement. The side walls were 3mm. ply, and the sail groove/track was a slotted PVC tube.
Hi Dick,
thanks for your comments.
I’m considering two options, with the swing rig, the permitted one consisting in the double luff (class M) and the second a rotating +/-25° FBG fairing around mast.
My above picture is just a simple trial to check weights and probably will no go on due to the excessive weight projections.
The projected weight of the 190cm long rotating fairing is 68g + 25g for the traling CF tube of 4mm. The copper rings will help to keep the fairing aligned with the mast, only 3 or 4 will be used. 1 ring = 0.55 g. total 95g
The leading edge with balsa :
The balsa leading edge will be around 28g and the calculated FBG lateral sheeting will be 60g + 25g for the trailing edge + rings = 115 g
The double luff will weight 23g only, is not very costly in term of weight and deserve a trial.
Obviously which one will be the more efficient ? Hard to says now and probably not worth at all.
One should bear in mind that the class I generally use are very restrictive, but probably the AC120 since nothing is forbidden yet.
The Mast Wing that I have partially assembled (see above message 9) is 139g but is still missing a layer or two of CF to get it very rigid and at the end will arrive at 193g.
The actual Mast in CF under preparation for a swing rig, with 14,12 and 10mm tubes is 129g , the booms are missing, but no shroud and no spreaders.
I will continue to develop the FBG fairing even I’m pretty sure that the weight will be too high to become an interesting option …perhaps !
Cheers
Claudio
Maybe a boomless mainsail?
Just a flat carbon plate on clew of main with series of holes. Hook the mainsheet into the appropriate hole for wind conditions expected. Must have sheet location from directly under leech - hook to hole farthest out and it will flatten both foot and leach. Hook closer towards mast and it will add camber, and also loosen leech for sail twist.
Just another idea !
Just think if we were to sit over a good beer or wine - how many ideas we all could share in one evening 
!