Hi DaveS,

If you still don’t understand, then please point out precisely what I said that you still don’t understand and I’ll try to explain that point further to clarify it. Similar looking motions can have different aspects to them, which I tried to make clear. So you need to be more specific.

PeterS

Hi DaveS,

These are flapping blades, not blades with a steady pitch angle. So there is not the similarity you suggest.

PeterS

Hi DaveS,

If it works as proposed, the flapping of the blades would be a relatively short distance from side to side. The maximum pull should be when the blades are all the way to one side or the other. But that is not certain, so this really needs to be tested to see what happens. High tension in the tether would reduce the side to side flapping distance.

If the blades were horizontal and in a rigid frame (as I showed in another Fluttermill sketch), then they should work well, producing one pull-up stroke per cycle. As to what is most practical, I don’t know.

PeterS

Hi DaveS,

You make a very good point about long period vibrations and about sailboats tacking upwind as vibrating. When sailboats tack upwind, they can be seen to function as oscillating type, vertical axis windmills.

In fact, if two sailboats are connected by a very long shock cord so as to create a loosely connected catamaran, and they tack upwind in opposite directions, first apart and then toward each other, a marker at the center of the shock cord will be seen to move directly upwind. So it can be argued from that example (and others) that sailboats with sails are able to sail directly upwind – at least this special kind of sailboat.

Andrew B. Bauer, builder of the Bauer vehicle (land yacht with the wheels driving an air propeller) that sailed directly downwind faster than the wind in 1968, later published a design for a sailboat that uses long trailing arms, each with a sail and a centerboard at the aft end. It would be capable of sailing directly upwind. The long trailing arms allow the sails to “tack” or oscillate while the body of the boat moves directly upwind. The sails drive the centerboards back and forth, which makes then function as vertical axis propellers. (Some pitching of the centerboards might also be needed, but I can’t remember if he provided for that.)

PeterS

Hi DaveS,

Unfortunately, the pictures you sent were blank rectangles.

In my opinion, after struggling for years to determine accurately analogous sailing craft, analogies between WECS tend to be more productive when they are based on how the devices function rather than on how they look.

Thanks for telling me sailing directly upwind is a specialty of yours. We share that interest. Minor correction: The inventor of the directly-upwind arch kite you are referring to is not “Dr. Anders”.

https://sites.google.com/site/iwworldswidestkite/   Anders Ansar Arch Kite -- for sailing directly upwind, and possibly directly downwind faster than the wind (DDWFTTW). A wonderful invention!

Here is something that might interest you. He claims that it could probably sail DDWFTTW using the same technique as for sailing directly upwind. With all due respect to Anders, who I greatly admire, he’s wrong. It could sail DDWFTTW, but not by using the same technique.

If you like physics puzzles, you might enjoy these: 1) Explain why he is wrong. 2) Explain what technique he must use to sail his arch kite DDWFTTW. The first puzzle is fairly easy, but the second puzzle is more difficult without first understanding the Mill-Prop Principle. The Ansar Arch Kite is a Mill-Prop craft, and a very unusual one.

I hope to include these puzzles in my book on the Metatheory of Sailing, which will include an explanation of the Mill-Prop Principle (one of the four basic ways to sail). Kids should be able to sail DDWFTTW on roller skates by using an Ansar Arch Kite. It would make a terrific science project. Did you ever try it on bicycles?

Do I understand you to say that you used bicycles to sail directly upwind using an Ansar Arch Kite? If so, that’s marvelous! Please send me your information so that I can be sure to include it in my book. I would also like to know about your gyroboats that you sailed directly upwind. Do you have photos? I would love to see them. I really like windmill boats. (You may recall the photo of my 1978 windmill land yacht, driven by a Sharp Cycloturbine, that could sail in all directions. On paper, I’ve invented new ways to sail in all directions faster than the wind, and some new ways to sail only DDWFTTW. Most of them are windmill craft, although the usual distinctions between windmills and propellers often breaks down due to the relative motions involved.)

PeterS

Hi DaveS,

Your questions are broad ones about definitions regarding what you call “wingmills”, but not relevant to understanding the specifics of how the Fluttermill blades can synchronize 90 degrees out of phase. Please be specific about what you do not understand about that.

Please let me reassure you that I am aware that Flipwings are not constrained to a precise swept area as are Fluttermill blades.

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I am unable to find any information about the Flipwing, such as published papers; vector diagrams; analysis of the effects of proportions, mass, tension, etc.; testing data including power curves; etc.. If you have any, please refer me to them. Thanks.

When I’m sure that we both understand Fluttermills and Flipwings reasonably well, then we can discuss definitions and categories if doing so might be productive.

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If I understand your comment about how most kites can self-launch from the ground (a dubious claim), especially sled-kites, you are implying that if the wind direction reverses while the kite is on the ground, the kite can still self-launch. I don’t see how that is possible. If it is not possible, then that method of launch and retrieval is not reliable. It also requires the dedication of a very large area of land to the kite, which would limit the use of the kite. It also does not address the problem of protecting the kite from high speed winds. And leaving a kite on the ground for days at a time poses many problems, both for the kite and for animals, such as cattle, that could become entangled. So as far as I can tell, and please forgive me if I am wrong, you do not have a practical launch and retrieval system for the Flipwing. I assume that one could be devised, but I’m concerned that it might be prohibitively expensive. I would like to find a cheap and simple way to do it because the Flipwing, in my opinion, has potential.

The Kayakite that you mentioned is launched and retrieved manually, according to their website. It’s an interesting kite.

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Thanks to JoeF for finding the video 72, which I couldn’t locate. From the video, it appears that the kite is relaunching itself, and that is impressive. But the video doesn’t address the issue of a large possible change in direction of the wind between the time that the kite lands on the ground and then later tries to re-launch. So this type of landing and launching from the ground (or water?) does not appear to be reliable because it is not autonomous and automatic. If human intervention is required, the cost of the energy will greatly increase. As far as I can tell, kites will require towers for reliable launching and retrieval, plus computerized controls. And that gets very expensive. So small-scale energy kites may not ever become competitive with small-scale wind turbines. I say that because computer-controlled cycloturbine VAWT are not competitive at small-scale (so far) due to the added costs

PeterS