but have some more questions, mainly about building the soft part of the rig and I’ll post questions as they arise. Thanks in anticiapation of your assistance.
I have also had the idea of a Team Phillips platform built to the F-48 Class rule (similar to Mini 40), so will be most interested in seeing what you develop. Be sure to check out the multihull section of this forum.
Regards,
Bill K
welcome to the forum. I too look forward to seeing your efforts with a large multihull.
You may want to correspond with the class secretary Mark Gee of the 10 Rater class, since they have monohulls using rotating masts and have them pretty well engineered to stand up to racing stresses.
Go to our US AMYA page, and then to 10 Rater class where you can begin email dialogue with Mark. I believe last year he was over there in the U.K. to race in their world competition.
You’ve provided some really interesting leads and I’ll follow them up before I ask too many questions. I was thinking of a wingmast and soft sail but the hard wing mast looks very interesting.
My 2metre catamaran is well underway; I’ve moulded the shells for the hulls/floats - they’re in carbon/glass/epoxy and each shell weighs it at just a tad over 1.5lb. I’m currently building the crossbeam, this has a foam core laminated with carbon/epoxy.
I’ll post pictures as I progress and when I have somewhere that I can locate the images to link to.
I have a couple of U.K. contacts if you are interested … Mike Friend and Robbie Nevitt. Another who was invaluable in helping us get multihulls off the ground here in the US was Mike Howell - who, unfortunately has passed away. Along with Andy McCollouch and Anthony Wright and I believe that pretty well covers those that were/are instrumental in the development of multihull r/c sailing there in the U.K.
If I can be of any help getting you in touch with Robbie or Mike Friend, please let me know.
I’m already a multihull sailer in the UK; I have a mini40 and know Rob et al through the BMMA.
I don’t thimk Andy has sailed multi’s for some time and one of the main current exponents is Mike Dann; he moulds some excellent tri’s and cats. Here’s a link to one of his boats in action:
Well, there’s a lot of info and therefore choices to make.
My riginal thinking was a simple wingmast with a soft sail but Claudio’s discussion, and especially the french site he references has got me thinking about variations on even that theme. And, then there’s the wingsail in one of Bill’s links.
I guess, for a given area, the solid slotted wingsail will be the most eficient, followed by the wingmast with soft sail (and then conventional soft sails). But then you introduce weight and it gets more complicated - with the technology available to me to build a solid wingsail is always going to end up with a rig weighing more than a wingmast/soft sail.
Currently my inclination is towards the approach documented on the French web site:
I’ve also been thinking further on constructing a solid wing sail, with flap as per the link Bill posted.
Whatever approach I end up with the rig will be unstayed, swivelling in a tubular socket spanning from deck to keel. With that in mind I will need rigs that are stiff but light.
For ease of construction Bills vaccum-bagged foam cores look repeatable and relatively easy to construct but I suspect wouldn’t be strong enough or stiff enough for my purposes and are likely to be heavier than a ribbed construction. So how about a compromise based on a foam core…
Get the foam cores cut as symetrical halves with a semi-circular channel cut into the ‘inside’ face of each half. Glue a suitable pultruded carbon fibre tube into the channel and glue the two halves of the core together. Finish the outside of the core with some very light cloth, or maybe carbon fibre tissue, just enough to give some durability to it. When its all cured remove areas of the ‘wing’ to leave a foam cored ribbed assembly that can be covered with a suitable model plane wing covering. Carbon fibre plates at root and tip will take the flap pivots and transfer the loads into the carbon fibre tube spar. The foam core will not take much of the load.
1.5metres of high modulus 12mm carbon fibre tube will weigh around 75-80g ((about 3ozs). A variation might be a tapered carbon tube, which might save another 15-20g.
Incidentally, I weighed the swing rig from my mini40 tri and was quite surprised that it is close to 300g all up. It has all carbon spars and scrim sails.
Ray,
Sounds like a very viable approach. I agree that my composite foam core mast would not be able to withstand the rather severe bending moment at the base of an unstayed rig. Also, you will need to significantly reinforce each hull at the mast step to handle these same loads. This is more of a factor on the narrow amas of a catamaran than it would be on a wider monohull platform, so you might not be saving that much weight overall, but at least it will be low, not aloft.
Are you considering the unstayed rigs for aesthetics or function?
The need to minimize weight aloft is essential, especially with the twin rigs of Team Phillips.
Your weight numbers for the CF tube spars sounds on target. Recently I’ve been developing a stayed sleeved luff rig for my new landyacht design ( http://www.youtube.com/watch?v=RrkUB1UIhzw ), using a tapered CF fishing rod tube that comes in at 90g for a 1.75m spar. The beauty of these simple collapsable rods is that they only cost about $8 (made in China, of course…;-( ).
If you’re seriously looking at the rigid wing approach, here’s a couple other websites to check out:
John Eisenlohr (the Montana dirtboater who build the model wing) also has a discussion group at: http://sports.groups.yahoo.com/group/wingboats/ I’m sure that John would offer comments if you posted on this forum.
Kris Seluga has developed a sparred wing (with fabric) for use with his LS-4 landyacht kits: http://www.rclandsailing.com/
Team Phillips was built in Totnes, Devon, England, only about 45miles from where I live and I visited the visitor centre and witnessed the hull structure being finished. It really was big - in fact it was a close fit in the River Dart down which it had to be towed several miles. It was fast too - shame about the structural failures.
The more I’ve considered the options the more I’m gravitating towards solid wingsail rigs similar to the John Eisenlohr approach that Bill posted, constructed as per my previous post with cutaway foam cores.
In his article John showed how he arrived ar the flap pivot point. and I’ve now put together some initial drawings using his method to derive the pivot points at the root and tip.
On the basis that if you can use components for more than one function you can save weight my thinking is to position my carbon tube spar through the flap pivot points and to also extend the spar into the hull as the pivot for the entire rig. This positions the spar near the back end of the main wing section but I don’t think that is a problem structurally. However, it does make the rig pivot point only a vary small distance forward of the rig centre of effort (I’ve assumed the CE to be the geometric centre of the rig plan, i.e. the point of intersection of the diagonals) and I think this may inhibit the ‘weather-vaning’ of the rig with a conventional sheeting cord approach so I may have to devise a direct control mechanism for rotating the rig (as you would a rudder) but this is complicated by needing to keelstep the spar tube - any ideas/observations? On the upside, this would seem to mean the rig is almost balanced so it may not need the power of a big sail winch servo to rotate it?
Does anyone have jpeg images (or similar) of naca 0015 and 0020 profiles. To order the foam cores I need to import them into my drawing package to devise the hotwire cutting profiles - bear in mind the foam cores will be in sections so I can embed the carbon tube spars.
Ray - here’s a photo of the model wing under construction by one of the guys that raced the C Class catamarans representing Canada — and winning over the U.S.
Perhaps a view may help the idea process. I never saw final version of the model wing - but the big full size one sure kicked butt.
Let me know and I’ll try to re-establish contact with him and get you a good email address. Might just as well go tot he source - and someone who’s “done it” !
Lester’s source looked very interesting, but if you’re simply looking for some images to play around with you may want to try this. http://www.ppart.de//programming/java/profiles/NACA4.html . He has the NACA 4 & 5 digit series & they can be adjusted to whatever profile you want, then printed off & copied. Larger sizes would involve some cutting & pasting
Although you certainly could come up with a digital file of your section(s), it probably would be possible to tell your wire cutter what NACA profile you wanted (tip & base), then he can split it in half digitally & add the hollow for the spar. It will be quite a project.
As a sidelight, I thought I’d show the rig I recently created to use on my K2 landyacht project. I wanted to develop something simpler & quicker to build than the composite masts, so I’ve come up with a prototype that draws on lessons learned with the Footy McRigs, as well as Claudio & others. It adds up to 235grams, but could be lighter if I wasn’t using the stiff 4 mil (.004") Mylar for sail & airfoil shaped luff pocket. I like the way the heavier material forms & maintains a good shape. It is 1.75 m tall.
Thanks for the further information and ideas. I think the next step I’ll take is to build a simple prototype wingsail for my Mini40 trimaran. I need to check out a few ideas and learn more before I go headlong…
just a quick question for clarification, since the post says one thing, but you are saying another - just semantics, I’m sure…
Are you building a wingmast - or wingsail? The mast is one thing and is used extensively in mulltihulls and now moving to monohulls, while a wingsail has really been limited in use to mulltihulls, and primarily the 18 Square Meter, C Class, A Class catamarans and perhaps a few one-off speed record attempt boats.
Dick,
That wing was designed & built by John Eisenlohr from Bozeman, Montana, referred to in the 2nd post of this thread, 3rd link. He’s a real craftsman, in fact is a professional cabinet maker, plus an all around good guy. I’ve spoken with him directly several times when I used to attend the spring dirtboat races at Dry Lake Ivanpah on the Nevada/California border. He does alot of full sized stuff, as well as some wind tunnel testing.