wing sails

[nflutter]

im interested some information regarding wing sails like on the C-class cats, and double skin sails like a few people are experimenting with on boards, as well as solid wings like the monofoiler and sailrocket, yellow pages, Macquarie innovation etc.

i know boats like stars and stripes, the infamous Americas cup cat run multi-stage wings that tack, and some have slotted 2d profiles and various permutations of multiple symmetrical foils that relate to one another to create an efficient shape and hopefully some good lift. im especially interested in the wing on the latest C-class from Australia, sponsored by ronstan, i like the shape its more organic.

forgetting that a wing for a dingy has to provide that functional requirement of working on both tacks, what would be the most efficient 2D wing profile be for a small, relatively light boat? would it have flaps? what about planform? would it taper or be relatively square, swept back etc?

does anyone know what foil section they use on the asymmetrical boats such as sailrocket, yellow pages and all the different variations?

also how do solid wings perform over a wind range? how are they de-powered? i have noticed some of the newer designs can alter the 'cant' of the wing, do they still only have a narrow wind range or does this help?

what kind of lift coefficients are achievable with a tacking wing as compared to an asymmetrical wing as compared to a double skin sail as compared to a standard sail with a wing mast?

[yipster]

what was infamous bout america cup runner stars and and stripers, thought the boat proved a point
bunch off questions i'm studying also, a spitfire wing had the ideal 2d profile but was later also cliped
search the net and read http://www.tspeer.com/ pages, not easy to find but read some books on the subject
missed mentioning inflatable sails and what else but think it sure is a interesting question, keep me posted

[nflutter]

thanks for the link theres some good information there that pretty much covers all my questions and is relelvent to what im doing.. i guess i was trying to find a bunch of differnt theories on the subject. your right inflatable sails are an interesting sollution. i think in the long run thats where its at for dinghys. some problems to overcome.

[nflutter]

K so sorry to bring this up again but despite heaps of searching I still haven’t found an answer to my original question.

Q: What would be the optimal wing section for a 10m2 solid wing sail max speed 30kts? Forget flaps etc.

http://www.sailrocket.com/images/homemainimage.jpg

[CT 249]

Search for "Steve Clark" here. Somewhere in an old thread he gave the section details for Cogito's wing - along with the recommendation that getting everything light and workable was much more important, I think.

[tspeer]

Originally Posted by nflutter

...Q: What would be the optimal wing section for a 10m2 solid wing sail max speed 30kts? Forget flaps etc....

There's not a single answer to your question. You would need to define much better what the operating conditions are, what the design constraints are (for example, do you need a certain amount of thickness for structural stiffness?), and then design a section to meet your specific requirements.]

Unfortunately, the tools you need to design a multi-element section, like MSES, are in the professional price range.

For the sections shown on my web site, I used an analysis program called MCARFA, which is an old code from NASA that is really not well suited for low-Reynolds number sections. And since it only does analysis, you have to find another way to design the shape. The sections I've shown were my first attempts at seeing if I could use the Eppler code, which only handles single elements, to design pieces of a multi-element design, and have the whole thing meet some specific design objectives. I found that I could do a pretty good job in just two design iterations with the main wing section, but my attempts at designing the flap section were less succesful.

Nevertheless, the data from the sections on my web site may give you some inital numbers to start off your design cycle.

[yipster]

Frank Bethwaite compares a gliders wing with a high aspect sail in “high performance sailing” For upwind sailing the optimum theoretical aspect ratio providing the best lift to drag ratio should be the highest that can be built writes Tom Whidden in his book “the art and science of sails” but also that the value quickly diminishes turning of wind.

I’m gone read Tom Speer’s site again on mast rotation and wonder what effect slats and flaps have on broader courses. Dividing luff by foot is easy enough but “high lift system aerodynamics” gets way more complicated, high time I’m reading up on all this fascinating but complex stuff

[yipster]

collected some slats and flaps from the internet

[tspeer]

I believe the attached file, "High-Lift Aerodynamics" by A. M. O. Smith, is the finest single paper ever written on the subject.

In his Wright Brother's Lecture, he explains:
- why a higher number of multiple elements (slots) produces a higher maximum lift than a fewer number of elements
- the five mechanisms by which a slotted section increases the total lift
- why thickness is harmful to maximum lift

There's a great deal to technical detail, but his writing is understandable even if you ignore the math.

However, high lift is not the most important aspect for sailboat rigs, even for craft like the A- and C-class cataramans that have constraints on their sail area. What is important is producing high lift with low drag. It is absolutely crucial that the drag not get out of hand in the search for higher lift.

In this regard, aeronautical practice can be somewhat misleading, because drag on the landing approach is actually helpful because it steepens the approach angle. This is why so many gliders have spoilers but no flaps. So aircraft in the landing configuration can go for high lift without regard to the drag penalties. If you want to look to aircraft for ideas on sailboat rig design, look at the takeoff configuration instead, because takeoff requires a high lift/drag ratio, making it more like the requirements for a sail rig.

[yipster]

a late thanks here Tom, still on it i came acros the "little americas cup" C class catamarans that i like and want to share

[Paul Scott]

[quote=yipster;134609] a spitfire wing had the ideal 2d profile but was later also clipped


BUT! The extreme high altitude Spit had extended wings that were REALLY pointy. Go figger.

[Phil Stevo]

and the mustang has square tip wings and out performed the spitfire.

There is along C Class thread on Sailing Anarchy. with the details Chris refers to.

[yipster]

thanks Phil, missed that conversation and courious for more inf on c class
http://www.sailinganarchy.com/forums...245&hl=c+class

[frosh]

By coincidence, "Ronstan" is housed at my yacht club, Nedlands in Perth.
This means that I have looked over the wing sail and hulls virtually with a magnifying glass, as it was there in the same shed as my tacking outrigger, the one I have been referring to on this Forum. Well, actually the hulls were outside the shed, but the wing, always inside. Sometimes the wing was at chest level while the designer/builder was working on it. He and I had a few conversations on the construction details. He recommended that I scrap my soft wing sail (As in James Wharram's "Tiki" design), and try out a smaller rigid wing sail, (ala "Ronstan"), and also go to a singlehanded arrangement to cut down significant overall weight for my boat.
The real issue of this posting is not that however, but I wanted to know all the materials in great detail, and also about the framing detail under the skin. No answer was given to me on this stuff, as I can understand it must be part of the sponsorship agreement.
However I was absolutely assured that it was in line with best available techniqes and materials available, and price and difficulty to construct, were not at all the limiting factors. I must say that it looked like a "Spitfire" fighter/bomber wing but perfected in shape, more organic in appearance, and as smooth as! I was extremely impressed by this wing.
Nevertheless it broke fairly early on during the C-class challenge series. This indicates to me that the shape is probably secondary to getting an efficient wing that can be articulated correctly under racing conditions, and also will not break up after a small amount of racing use.

[Paul Scott]

frosh, you do live a we bit o' paradise. Be you an AYRS member too?

Paul