Highly Assymetrical Wing Sail

[TeddyDiver]

Originally Posted by ancient kayaker

. If they were light it might help keep a level keel, although a beam sea could push the kayak around a bit.

I think the ama is perfect for balancing the CE being so much on the same side. Might even be handy having some kind of rudder out there to assist steering and maybe even use it as assist brake in sudden gusts..

[ancient kayaker]

Eric: I looked for "Aero-Hydrodynamics of Sailing" -it is too rich for my purse but Tackwind sounds like what I am proposing.

Teddy: balancing the CE should not be a big issue as the wing's lift vector points at the mast's pivot, at the center of the deck. The weight of the overhead rig may be a problem but looks doable if I use my most stable kayak; I think I can bring the moment down to about 25% of the boats limit. The ama's on the wingtips are out for weight reasons. If they are inflatable their weight could be tolerated but they would then only be of value to avoid a capsize, not for actual sailing and the top one would catch the wind. For steering I was planning to use The Articulated Sailboat concept turning the entire rig including hydrofoil(s) with a fixed skeg to keep the hull in line.

It is starting to look weird: I like that.

[Chris Ostlind]

Couple of things, AK...

I can't recall seeing the amas in your plans and have no idea as to what size of a form you might be suggesting.

At the speeds at which you will likely be traveling, I tend to believe that the ama forms required for sailing will not create as much of a source of form drag as suspected. I'm guessing, then, that you are planning on doing a good bit of body english to take care of things while the foils get hooked-up?

Your most stable kayak...? How is that going to effect drag, as opposed to the possible drag from a raised ama?

There is potential here, to be sure. Perhaps some additional drawings depicting various size relationships, etc., could help me to better visualize the design better.

ChrisO

[TeddyDiver]

Originally Posted by ancient kayaker

It is starting to look weird: I like that.

Me too
With CE I meant more it being far lee side so you need at least a sheet to hold it in right angle otherwise it'll turn forward..

[ancient kayaker]

Chris: there were no amas in my original plans; the concept is still in motion as I get inputs. My best kayak sail was only 15 sq ft, lost in a fire alas. That was decent for run and reach but inefficient upwind. A wing about the same size, weight permitting, should work better.

The amas I referred to are the wingtip mounted floats suggested by Daiquiri and Teddy.

Bruce foil(s) will take care of any wind-generated heeling moment; I used one with the old sail and that was safe and easy to use. “Body English” can balance the offset rig weight, just lean over a few inches, or I could put small ama(s) on the Bruce foil outrigger(s).

Drawing isn’t my strong suit but I should have something soon, however I first want to design a lightweight sail; low-tech; I don’t want to get into composites - looking at beefed-up model plane construction. I am also still finalizing my design for the kayak attachment and blending in the articulated sailboat concept.

Teddy: sorry - I misunderstood you. The pivot has a fore-and-aft axis with enough length to react the moment generated by the wing's forward thrust. A hard stop will prevent the mast from over-travel sideways. I am looking at wing dihedral as a means to automate the flipping of the wing during changes of tack, I need to do some modelling but my memories of tow-launching model gliders suggest it will work. If that works OK I don't think there will be a need for a sheet unless it has to be pulled all the way down to the stop and lashed.

[ancient kayaker]

Here's a sketch. This incorporates the concepts of the following threads which may help understanding the entire concept:

Sailing Kayak Project
The Articulated Sailboat

[tspeer]

Originally Posted by ancient kayaker

The idea is to mount a wing on a Vee-mast that can be pivoted from side to side. When changing tack in this way, effectively the wing is flipped top to bottom, rather than side to side. Therefore it no longer has to be symmetrical and can instead adopt a more efficient profile such as those used on sailplanes. To eliminate problems controlling alpha, the wing has a small controlling foil mounted on a stub, operating like the tailplane of an aircraft, so alpha control is automatic. ...

What you've described is known as a fliptacker. A fliptacker named Wingmill competed for the C Class Catamaran Challenge Trophy. Unsuccessfully, but your aerodynamic control may be more effective than Wingmill's manual control.


Bernard Smith wrote a book on these craft called "Sailoons and Fliptackers" that was published by the AIAA. It's out of print, but you might be able to cruise the net for a copy.

[ancient kayaker]

Thanks Tom: Now that's what I call a thought-provoking picture, with the crew barely visible far above the water. I wonder if they are trying to right her or are just some pieces of movable ballast left high and dry. If I don't know what I am doing I at least know what it is called, I thought I was first with the fliptacker!

There are quite a few stories about the difficulties of controlling wingsails and the consequences of failure in that department. I should clarify that the control foil is not my idea, there are several successful examples that I am copying. Perhaps I will be (one of) the first to put these two ideas together.

As far as I know, the articulated sailboat concept is genuinely new, I suspect that is because it has no real practical application to boats larger than a kayak. That's rather a lot of innovative ideas to try and marry together all at once (more of a commune); I intend to implement them one or two at a time and also try out a small hand-held version of the flipwing to see how it behaves on it's own.

One thing I always do with sailing rigs for a kayak is incorporate some kind of quick release to dump the rig over the side during that kind of maturing experience. Your picture has reinforced my resolve!

[Munter]

ak - I'm pretty sure you don't right a C-class and keep on sailing. That pic is a moment of disaster just before the wing hits the water and (from memory) disintegrated beyond repair.

[ancient kayaker]

No doubt about it. Gives "flip-tacker" a whole new meaning, doesn't it!

[Munter]

Very true AK. A quick web search reveals a claim from Wingmill's home club (Cabrillo Beach YC) that the capsize was caused (in part) by downwash from a nearby helicopter. What a dissapointing end to such an abitious campaign. They must have felt terribly hard done by after getting the boat all the way to Australia.

The wing on Wingmill appears to have several degrees of freedom -perhaps evem more than appear on most flip-tacker models I've seen. I wonder if that contributed to the difficulty in coping with the helicopter down-wash?

[catsketcher]

If stability is a concern in the kayak then how about a little float? I have gotten right into kayaking in the last couple of years and can't quite see why most kayakers won't consider an outrigger canoe for voyaging. Most kayaks are pretty unsafe machines and yet we like to paddle in them. If you are serious about getting a sail and staying stable I would think that the complexity of a small float and crossbeam setup is far far lower than that of any new rig. The only problem is that it has been done before and proven - for thousands of years by the Pacific islanders. Kayakers tend to be more Eurocentric or more correctly Iceland centric and like to spend lots of time learning how to roll. It is the great mono multi divide raising its head in a different field. I can't see why you can't design out the need to learn how to roll by adding a float! Right now Gary Dierking is using an outrigger to cruise Fiji. He has some great outrigger designs

cheers

Phil

[ancient kayaker]

Originally Posted by catsketcher

If stability is a concern in the kayak then how about a little float? I have gotten right into kayaking in the last couple of years and can't quite see why most kayakers won't consider an outrigger canoe for voyaging. Most kayaks are pretty unsafe machines and yet we like to paddle in them. If you are serious about getting a sail and staying stable I would think that the complexity of a small float and crossbeam setup is far far lower than that of any new rig. The only problem is that it has been done before and proven - for thousands of years by the Pacific islanders. Kayakers tend to be more Eurocentric or more correctly Iceland centric and like to spend lots of time learning how to roll. It is the great mono multi divide raising its head in a different field. I can't see why you can't design out the need to learn how to roll by adding a float! Right now Gary Dierking is using an outrigger to cruise Fiji. He has some great outrigger designs

cheers

Phil

I have tried several schemes for sailing canoes and kayaks. It's turning into an informal mini-research project, I suppose. My first canoe sailing rig had a float or ama; it was quite large (7', 2.1 m) and I intended for it to stay in the water full-time. Only about 35 sq ft (3.5 m2), not enough sail really. I sailed with my weight off-center to ensure that. Performance was disappointing. It was a while before I realised how much it was slowing the boat: one day I was moving really fast in a modest breeze and I looked around to figure out why and realised the float was out of the water.

I could have improved the float design but the trick when sailing with floats is, either have a large sail to overcome the extra drag or balance the sail using weight and keep the floats out of the water, then they are only backup in case of a sudden wind change.

Later I tried a sail on a kayak: you can't hike out in a kayak the way you can in a canoe so I needed to balance the sail's heeling moment without using body English. I used a Bruce Foil to do that and it was successful and felt reasonably safe. The kayak I used was quite beamy which helped, but the foil was doing most of the work. Again a very small sail, 15 sq ft/1.5 m2, and a crude plywood foil. I had a lot to learn then. Still do.

Currently I am finishing a small sail boat but when that's done I want to get back to my experiments. This is just one of them. The principle being tested is angling the sail so the sail's thrust vector passes through the boat's center of gravity. At the same time I am trying out the idea of a wingsail with automatic alpha control. I will use the same beamy kayak so I have an extra margin of safety but I believe this will be a stable system when in a steady state: it's the reaction during changes of tack or wind direction I worry about. I have a nice shallow lake to try it out on with a muddy bottom so I am unlikely to hurt myself.

I have been delayed with my boat projects this year, health and family challenges, but I will get there!