Thread: DIY Wing Sail
25th Mar 2009, 11:52 PM #1
DIY Wing Sail
Thought people might find this of interest.
A DIY, fully configurable, polytarp wing sail.
Old memories of this web-site were stirred by a posting in another forum.
This bloke has been refining his design for several years - now up to revision 6.
Thought about knocking one up for Teal at about revision 2 but felt the batten
construction at that stage was beyond me (cast your own variable-flex in
epoxy & glass rovings) This latest version of batten looks eminently do-able.
It is a complex beast, but dirt-cheap for what it theoretically might do (thrash the
pants off a Storer OzPDR !!)
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26th Mar 2009, 12:39 PM #2
Ya just gotta love it when some one uses "back yard" materials with a little modern technology.......... It's a good read and makes you think which is a good thing.
Should raise a few comments from around the traps
26th Mar 2009, 05:20 PM #3
Looks like fun ... don't know about efficiency though. He needs another boat with the conventional rig to find that out.
I remember the struggle that the C-class cats had with getting wingsails to perform better than conventional sails .. or even consistently. Was a real struggle through the '70s and '80s
26th Mar 2009, 08:28 PM #4
I remember some of those boats. Miss Nylex & others.
Got a vague recollection that their wing sections were not as configurable as this one.
Pretty much fixed thickness wings or wing masts, & without the ability to vary both
convexity & concavity of their surfaces on demand. But I was a distant viewer so
could have easily not noticed some important details.
Practically, while it would be an interesting exercise to make & use one of these
things in serious competition, I am fundmentally a lazy sod & not competing.
A Storer tweaked lug is as much work as I now care to put into my sailing.
26th Mar 2009, 10:07 PM #5
Many have fooled with this idea over the years. The most famous one was the inventor B. Ljungstrom and these double thickness sails are usually called Ljungstrom rigged.
The marriage of a semi rigid foil with the Ljungstrom is interesting, but I feel it's overly complex.
I've been toying with a new idea for a semi rigid leading edge which also uses vortice generators to help improve flow.
I'll probably build one this summer or fall. It uses a conventional sail, but the mast is fitted with a foil, with attaches to the luff of the sail. The idea was the ability to retro fit current free standing rigs with an adjustable foil shaped leading edge which eliminate the "mast shadow", but more importantly permits a "slat" of sorts that dramatically increases lift.
Basically it's a set of foil shaped hoops that are fitted inside pockets, sewn to sail fabric, much like a batten would be. The hoops are hinged at the front making replacement an easy thing. The hoops are spaced the same as the cringles on the luff and their trailing edge has an eye to receive the luff cringle.
When hoisted the fabric pulls taunt from the halyard and the hoops cause a scallop shaped leading edge. It's looks like it would be a bad thing, but these are the vortice generators. Blue whales have similar bumps along the leading edges of their flippers and they're the most maneuverable of all the whales. Recent tests have shown these very bumps are the reason their flippers are superior to other whales. Since I've played with this type of thing before, I figured I give it another crack.
The advantages are huge with my setup. The sail can be reefed or doused, flaking neatly on a boom. Any free standing rig can employ it. It can be retro fitted to a conventional sail. It doesn't require "panel" layouts like a regular sail does. It can generate about 20% more lift then a conventional sail. It can operate at lower angles of incidence. Going down wind the foil can be cranked around to act as an end plate improving drive.
I should also add I'm using a full length top batten, but the rest are full length pneumatic battens. This saves weight and is very easy to adjust for different wind strengths which solid battens can't do. The total weight is about the same as a conventional sail, because the sail track is eliminated and the hoops are fairly dainty.
The only additional lines are a continuous loop to rotate the mast and it'll probably need two halyards to hoist the sail without the hoops binding on the way up.
My test bed will be an old Catalina mainsail which is about 95 sq. ft. I have a good idea how my test bed preforms with this sail, conventionally rigged, so comparisons will be obvious.
26th Mar 2009, 10:30 PM #6
Mm.....sounds very interesting, patent pending?
I'm having trouble visualising the way the luff is attached I think the sail would be set further aft along the boom so that the luff is say about 6 inches away from the mast. Guessing similiar to a windsurfer sleeve set up with the hoops maintaining the foil shape.
Look forward to seeing the proto
To me the wing falls down when sailing on a 3/4 reach through to running when the drive from the foil shape is lost and square feet comes into play. I figure it's a bit like engines "there is no substitute for cubic inches". Yes hull speed moves apparent wind forward which works on planing hulls but not much good for displacement.
Mind you an Aerodynamacist I'm not
27th Mar 2009, 10:16 AM #7
Mike, if the hull is slippery enough and offers enough power, you can sail upwind even when on a broad reach.
The double skin sails have issues, but it's a novel concept if it can be made to work.
Yep, the boom need an extension, but not as you'd think. Rather then add a piece to the outboard end, the gooseneck is moved outboard on a "stand off" attached to the mast. This permits the conventional portion of the sail to set independently of the luff foil. I worked up a mechanical vang (think big ass turnbuckle with a wheel attached to the body) that will act as a topping lift and a vang. I've used this setup on conventional boats and had my racer arranged this way until they banned it (everyone has to use a tackle vang).
You can run a masthead jib and a fixed backstay(s), but no spreaders.
I've looked into a patent, but quickly found a bunch of similar ideas, which all will need to be researched, etc. creating an economical environment that wouldn't be healthy for a new patent. I could just apply, then keep getting extensions to the application to have some protection, but frankly I can't defend a determined builders attempts to use it.
19th Apr 2009, 02:07 AM #8
22nd Apr 2009, 05:21 PM #9
did you see the email address on this page?
22nd Apr 2009, 08:55 PM #10
24th Apr 2009, 03:46 AM #11
Yes, Thanks indeed to Boatnik, who may prove to have only minor flaws :^).
Re Whale flippers, is it not the Humpback that has bumps along the leading edge of its flippers, not the blue?
Re C Class cat wings, There was an Italian entry called Signor G IIRC, and it had a one piece wing which had a complex series of tackles inside the wing form ribs which permitted the camber to be modified, and the side changed, by crew action during the races. However it was beaten in every race IIRC by the two or three section slotted wing of its opponent, and i don't recall who that opponent was, but I was surprised at the defeat because the Italian wing looked more like a wing should.
24th Apr 2009, 07:31 AM #12
Yap ... bumps work on a humpback which is waving its fins through the water at low speeds. If my centreboard acts like that, I will have to go out and get a new one
You are exactly right about the C-class wings, there have been a number of "more ideal" looking systems that have been completely trounced by something that looks more "agricultural".
However it usually comes down to three things.
1/ weight - lightness is everything - in almost every case it is the lightest wing with the best control that wins
2/ low friction. There was a little article somewhere about how the most recent OZ Little America's cupper had wing problems because of friction and weight from 200 blocks inside the mast needed to control the six or nine elements. They cut it down to 80 with good design. Purpose of the blocks is to be able to dial in repeatable sail settings.
3/ debugging - almost professional teams doing really careful comparison sailing to work out how to set the wings up. eg, broad reach in 17 knots of breeze, set twist of main elements, relative angles and distances of the subelements, also the feedback loop that improves #1 and #2.
Australia dominated for a long time because of these achieved with relatively simple and cheap materials. But then the US Cogito team did the same using a high tech and high expense route.
24th Apr 2009, 09:15 AM #13
To Boatmik. Good day Sir, said he displaying his Pom upbringing and Hi Boatmik from the last 50 years living in Canada. Seems to me that most of the fun went out of the C Class about the time that the Una Wings started to dominate. There used to be a fleet of simple C Class cats racing out of Vancouver but they seemed to fade away as old soldiers are said to do. I was gven the platform for one plus a mast Blank several years ago and, having just tearfully parted with my wing masted Tennant Turissimo 10+, am now addressing the issue of making this C Class more comfortable to sail for an old geezer as a day sailer. "How are the mighty fallen, they were swifter than eagles etc."
I suppose they were so much more trouble to trailer and assemble than say Tornados, without much more speed, and a lot more trouble than any of the 18 foot jobs being produced in quantity in the US. Plus of course the run of the mill sloop rigged C Class cats could not even pretend to be like the C Class jobs involved in top level and International competition. Perhaps not all of the owners had patient wives either:^)
24th Apr 2009, 10:40 PM #14
I quite agree. But actually the big una wing masts were fun too while it was all at a (somewhat sophisticated) backyard level ... which is what the Oz boats were like for the two decades they were dominant.
Beautifully light ply hulls, ply wing mast with a little bit of carbon and foam. All stuff that any of us could whip up if we owned 500 g-clamps! Theoretically anyhow.
But now has moved away from that.
Probably a sensible response as it was only possible for a decent challenger to come together from time to time. Most challengers were pretty crappy and unreliable and had big losses to most of the holders of the Little America's cup. Except of course the years the challengers were able to take the cup home with them!
During the early 70s, when I was starting out sailing, Helios, designed by Lock Crowther and bankrolled by the SUN newspaper and John Haines was sailing off one of our local beaches in Pittwater. They went too high with the wing rig apparently and had trouble controlling the power.
But amazing to this then 14 year old.
25th Apr 2009, 12:01 PM #15
G'Day Boatmik. Two answers in one. About fillets and tape. I was unaware of the work done by your local university on the appropriate range of sizes for fillets on various thicknesses of plywood. The standard approach here tends to be fillet and tape the interior angles and tape the outside corners. Perhaps we/they ( they being the US types) tend to be a bit more concerned with fail proof joints and less concerned about the cost of the epoxy and glass than the more prudent types down under.
Re the una rigs, Yes I know about building wing masts with ply and carbon, I built the 50 footer on my Turissimo ( we have lighter winds here than there). I would be thinking of making one for this C Class if an aluminum mast blank had not come with it.
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