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Thread: Birdwing mast design to benefit from new sail track composite material

  1. #1
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    Default Birdwing mast design to benefit from new sail track composite material

    Many folks have heard the story of how my fishing buddy’s loud complaints about the old straight mast getting in the way of his fishing forced me to glue up a mast that curved around him and stayed completely out of his way when it was stored on the boat.



    There’s also the story of how I managed to get Florida State University, my employer at the time, to pursue a patent on the design. It took FSU seven years and $16,000 to be granted a U.S. patent (#8,739,720) for what I call the birdwing mast. Essentially, the birdwing mast is a curved, blade-like foil set on a straight rotating stick. The official title of the patent is “Storable, sickle-shaped sailboat mast.” Why the sickle shape? The handle part of the sickle with its round cross section allows for smooth balanced rotation of the mast within the mast step. The curved part of the sickle-shaped design allows for a swept-back, aerodynamically efficient presentation of mast along the entire length of the mast in the airflow.

    For the purpose of illustration, I usually show the straight part of the mast emerging from the free-standing style mast step and then show its transition to the aerodynamically efficient curved part but there is absolutely no reason why any of the straight part need be above deck and in the airflow. That is why I can claim the birdwing mast can present a swept-back, aerodynamically efficient shape along the entire length of the mast in the airflow.

    When we talk about the most aerodynamically efficient shape for a curved rotating mast, in the past there have been limitations to the ideal shape because of the need to attach sail to the aft edge of the mast. The sail attachment system usually has some thickness to it that prevents the foil cross sections from having their most efficient shape. The most efficient cross sectional shape for a birdwing mast would be rounded at the forward edge of the mast and then ending at a point along the trailing edge - not the "D" shape generally preferred by straight mast folks. But because of the need to include the sail attachment system (which has thickness) to the mast’s trailing edge, the ideal aerodynamic shape for my masts has been elusive in my wooden prototypes.

    Of course, there are other ways of attaching a sail to a mast that do not involve any sail track at all. On my last birdwing prototype I did try hoops for sail attachment so I was able to shape the trailing edge of my mast to as sharp a point as I wanted. Using slices of polyethylene from black trailer tongue wheels, I made hoops that were fairly light, strong and very slick that worked great in the Texas 200. From the helm, I was able to hoist sail or strike the rig without having to touch the sail at all and from any wind direction. I did hang on to the boom’s end when I could because it was always better to have it in my hand rather than slapping me in the side of my head, if you know what I mean.

    Soon, however, there will be an even better way to attach sail to a birdwing mast. At this year’s WoodenBoat Show at Mystic Seaport, a retired racecar designer by the name of Hunter Gall showed me a section of sail track that he has been working on which utilizes carbon fiber infused nylon. This new material offers the strength and lightweight of carbon fiber but retains some of the flexibility and slickness of nylon. Hunter’s sail track is in its prototype stage but shows great promise. His track design is a modular one and currently made in 1’ sections that have puzzle joints at both ends so they can be built up for as long as a sail track needs to be. The beautiful part for me is that the stuff is flexible enough to bend along the curvature of my latest birdwing mast prototypes and it is very compact hiding nicely out of the airflow.

    This new sail track material will help me whether birdwing masts are eventually built in spruce or in carbon-fiber/epoxy or both. In either material, the track can be added at the end of the manufacturing process rather than needing to be included in the molding or machining part of the mast making production. This translates into lower production costs whether birdwing masts are eventually made as high-end finished units in carbon fiber or as a possible spruce kit for backyard boat builders. Whether this will happen in my lifetime or not remains to be seen. I will say that at this point, though, I’m optimistic!

    In the meantime, here are some pictures of me and Bernadette, my 14’ 8” John Welsford designed Saturday Night Special setting sail at this year’s WoodenBoat Show and a parting shot of her on the long way home back to Florida.








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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Is Kevlar really necessary for such a small mast? I wouldn't have thought the stresses involved warranted it.

    Have you done any modelling to prove that a curved mast has any advantage over a straight one?

    I ask because I too drew one out to sit on a prototype catamaran, without really knowing why.

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    Do not know where you saw in my text that I use Kevlar because I don't. I do use carbon-fiber/fiberglass sleeves and bamboo mandrels when making booms. They seem to work well together - very strong and light weight. I spin my booms on a barbecue rotisserie so the wetting out process produces less drips even when applying a single thick coat of epoxy.

    I ran into a guy at the show who asked me if I was interested in doing a virtual aerodynamic study of my mast to which I said to him, "I've been looking for you." I'm very interested in having hard evidence of any and all aerodynamic advantages the birdwing mast may have compared to conventional straight masts. I tried to get FSU to test their patented design on the birdwing mast in their wind tunnel but they wanted to charge me $4000. Since that time they have sold the patent back to me, the inventor, but I still do not have $4000 laying around for wind tunnel testing. To me, it's fairly obvious that the birdwing is more aerodynamically slick than anything straight up in the airflow but hard evidence would be welcome and long overdue in my opinion.


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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Sorry, brain fart re kevlar.

    Virtual test sounds interesting...

    My design is just a whimsy, and I have no actual facts of either it's efficiency, viability or strength. I drew out a large heavy weather capable fast wooden cat, around 60 feet LOD. If nothing else I'll build a 6 foot model and play with it.

    Good luck..

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    Thanks for the good luck comment. I think my luck with my birdwing mast design has been very good so far considering the very small of money I have spent building and testing it over the last ten years or so. Most of that money was spent building boats and masts and that is what I like to do anyway. Now that I own the patent, I sometimes have spurts where I would like to see it developed at a much faster rate than the turtles pace that I generally fall into. The birdwing design has been more of a research hobby to me rather than some big money making scheme although I've come to believe that it is a good design and certainly worth exploring further. And I would not have any problem spending the extra money coming in as a result of cashing in on the patent if given the opportunity.

    Feel free to experiment with the birdwing design in the UK. The U.S. patent #8,739, 720 should not affect you in any way unless you were to sell them (or use them) here in the U.S.A. - at least that is my understanding of the situation.


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    Default Re: Birdwing mast design to benefit from new sail track composite material

    I've loved your birdwing (much nicer than sickle) mast since I first saw it, nice work, keep going.

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    Default Birdwing mast design to benefit from new sail track composite material

    There's been progress lately in some respects regarding the birdwing mast. My cousin's husband has graciously put together a website for all things "birdwing" that hopefully will generate more interest in the design. The address is birdwingmast.com

    I also hired a new and upcoming boat designer by the name of JF Bedard who has recently completed drawing my next boat build in a 3D drawing program. His drawings include the first ever three dimensional representations of birdwing masts. The boat on which they are stepped (my next boat) is Captain William Short's Yangtze Pelican design which he conceived shortly before his death in 1986. Captain Short's drawings of the Yangtze were incomplete at the time of his death but the missing drawings were completed about four years later by his friend and business associate, Richard Campi. I have been in contact with Mrs. Muriel Short in regard to my plans to build the Yangtze with birdwing masts and she seems to be onboard with enthusiasm for the project. She said my masts looked "graceful" and in harmony with nature. And that made my day! I told Mrs. Muriel Short that I had thought about naming the new boat after Marisa Tomei originally but after speaking with Mrs. Short on the phone I felt the boat should be named after herself, the keeper of the Pelican boat legacy. She said that "Muriel" was too stuffy a name for such an exotic boat and suggested the name, Muri-Maru, which sounded perfect to me. Funny story, huh? I'll try to post a couple of the JF Bedard's Muri-Maru 3D drawings on this thread in the next couple of days and will also post a thread titled "Muri-Maru, a birdwing Yangtze Pelican ketch" which will feature just my next birdwing boat build.

    So I am continually working on birdwing stuff but real progress has been slow by any measure. But I'm having fun and when you're supposed to be retired, that's all that really matters. That and staying out of hospital.




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    Last edited by kenjamin; 07-06-2017 at 09:18 PM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Lots going on......will watch with interest. Always good to see someone with passion for an idea to keep pushing.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Here's JF Bedard's web site
    http://www.bedardyachtdesign.com

    And as promised here's an example of what he can do...

    Muri-Maru, a birdwing Yangtze Pelican ketch - my solution to the Texas 200
    boat design by Captain William Short, mast design by Ken Ford, sail design by Jeff Frank at Sailrite
    and rendering by JF Bedard

    (It's not everyday that you can look at carbon-fiber birdwing masts)


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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Here she is from the stern...



    Forward cabin has been reduced to a cuddy so that side bench seats can extend far enough forward to comfortably sleep on. In Texas, in the middle of summer, you need to sleep where the air can get to you - cooling is everything. That and the ability to carry lots of ice! Boat will be self-righting, nearly unsinkable, and row-able in a pinch.
    Last edited by kenjamin; 07-07-2017 at 08:48 AM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Just FYI, I'm not able to see any of the photos you have posted on this thread--just a little blank photo icon comes up on my PC.

    Tom
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    Anyone else have a problem seeing the pictures? My phone, tablet, and laptop are all seeing pictures just fine. Try your phone, Tom.


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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Ha! No phone, and I love it that way. But for whatever reason, I can see the images fine now. Very interesting. I love to observe your experimentation and thinking. Very different from my own approach, which is the point of this forum, I think.

    Tom
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by kenjamin View Post
    My cousin's husband has graciously put together a website for all things "birdwing" that hopefully will generate more interest in the design. The address is birdwingmast.com
    Access is forbidden.

    Puzzled by what pivots the mast. Must be the boom, because it almost seems that the sail alone would want to pivot it the other way. Puzzled by what the curve is supposed to do to aid aerodynamics - belly shaping?. I suppose it gives the sail a more elliptical shape a la Spitfire wings, which is the ideal aero shape. I knew a guy who patented elliptical shape for paraglider wing(tips) around 1990 which they almost all have, although many mfr consider that an obvious feature and resisted paying.

    Only one of your pictures shows that the mast is a blade, which is a separate aero issue. Nice if the angle of attack is right, although a case might be made for a teardrop profile. A straight mast could also be a blade, although maybe more whippy than a curve.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Thanks for the heads up on the problem with the web site. You seem to have to find the link that lists the patent # to get the right site if you are doing a search for birdwingmast.

    In answer to what pivots the mast "The answer my friend, is blowing in the wind." Yes, seriously, the birdwing's shape has so much length along the airflow that it simply weathervanes to face the wind direction. With the new boat, I hope to also control over and under rotation of the masts by means of some sort of yoke on each mast near deck level to see if there's any benefit to be had. But if a birdwing mast is somewhere near perpendicular to the water surface and simple bushings are in place, it will rotate in response to wind direction in order to face the wind. (even under bare pole)

    In my retirement I mostly bicycle my 26 mile loop of my city and watch the sea birds. Sometimes at the top of the bridges I find myself speeding parallel to flying Ospreys or seagulls or Pelicans. I can tell you for sure that none of them do much flying with straight leading edges on their wings. When working to windward you always have to subtract the drag of the mast from your forward progress so why not start with a more aerodynamically slick shape and see what it can do? It is at least worth exploring in my opinion. The good part is that the birdwing is not a wingmast at all. It can set and strike sail like a regular mast and under bare pole it's nearly aerodynamically invisible. It does not misbehave at anchor like some wingmasts do.

    I've got a picture of Bernadette in my front yard that also shows the blade-like structure of my latest prototype (her present mast). I'll try to dig it up for you and paste it in later.

    And yes, I do think the curve does add strength to the overall structure of the mast. It also makes it possible (working in spruce) to machine in excellent accuracy for the taper of the mast.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    From another pro-curve source at https://en.wikipedia.org/wiki/Elliptical_wing :

    Theoretically, the most efficient way to create lift is to generate it in an elliptical spanwise distribution across the wing


    Edited P.S... by efficient lift I am sure the source means best L/D, which ties into your low drag speculations. That not only might improve windward speed, but permit sailing a closer angle into the wind.
    Last edited by rudderless; 07-07-2017 at 10:40 PM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Nice renderings there! I always thought round or elliptical ports would make that look so much better.......from a personal perspective. What a hoot!

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by kenjamin View Post
    When working to windward you always have to subtract the drag of the mast from your forward progress so why not start with a more aerodynamically slick shape and see what it can do? It is at least worth exploring in my opinion. The good part is that the birdwing is not a wingmast at all. It can set and strike sail like a regular mast and under bare pole it's nearly aerodynamically invisible. It does not misbehave at anchor like some wingmasts do.
    .
    Modern research is showing that you don't have to subtract the drag of your mast. The mast actually provides significant forward thrust: as WB Sails (who have done a lot of CFD work) say "Traditionally, the mast has been considered as a nuisance only, creating air drag. It would seem to be more appropriate to think of the mast as part of the mainsail profile instead.As a consequence, the mast can add to the total drive of the boat, instead of dragging back like an empty pole would."

    As Tom Speer, Boeing aerodynamics expert and America's Cup wing designer says, any must with a vaguely wing-shaped profile does "misbehave at anchor" in some respects. I think he said that it's simply because fluctuations in wind direction are so small; a windshift affects the leading edge of the mast before it strikes the trailing edge. The mast will not begin to pivot until this new wind direction has moved aft of the pivot point. During that the interval between the wind striking the leading edge and the wind striking the trailing edge, the mast MUST develop lift. There's no way around it, is there? And of course the actual pivoting requires force and that force can only be generated by the wind creating a side force on the spar, and that side force affects the boat's behaviour.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by rudderless View Post
    From another pro-curve source at https://en.wikipedia.org/wiki/Elliptical_wing :





    Edited P.S... by efficient lift I am sure the source means best L/D, which ties into your low drag speculations. That not only might improve windward speed, but permit sailing a closer angle into the wind.
    As Wiki notes, of course, the key is an elliptical spanwise distribution of lift - not an elliptical foil outline. The two are quite different, since lift is affected by factors such as angle of attack, wind velocity and draft. And of course, we don't want elliptical spanwise distribution of lift when we are restricted by righting moment, as boats are in a breeze. In that case we want to create more lift lower down, and that's best done with a nice bendy mast. This is one of the reasons that heavily pre-bent masts were abandoned in the 1930s, along with the other problem of running downwind.
    Last edited by Chris249; 07-08-2017 at 06:56 AM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by rudderless View Post
    Access is forbidden.

    Puzzled by what pivots the mast. Must be the boom, because it almost seems that the sail alone would want to pivot it the other way. Puzzled by what the curve is supposed to do to aid aerodynamics - belly shaping?. I suppose it gives the sail a more elliptical shape a la Spitfire wings, which is the ideal aero shape. I knew a guy who patented elliptical shape for paraglider wing(tips) around 1990 which they almost all have, although many mfr consider that an obvious feature and resisted paying.

    Only one of your pictures shows that the mast is a blade, which is a separate aero issue. Nice if the angle of attack is right, although a case might be made for a teardrop profile. A straight mast could also be a blade, although maybe more whippy than a curve.
    Over-rotating masts normally over-rotate automatically under boom pressure.

    You're right, a straight mast can be a blade and the vast majority of wingmasts are straight. Whippy masts are much better on dinghies unless they are very easily driven and therefore have very flat sails. Normal wingmasts don't bend very well because of their wide chord and therefore they don't offer the gust response that is so vital in performance dinghies, unless the sails are so flat that they don't need much bend.

    Years ago Frank Bethwaite (of 49er etc fame) used to get around the inherent problems of stiff wing masts for small dinghies by making masts in spruce, and then fitting a balsa wing-shaped fairing to the leading edge. The balsa was then cut horizontally every few inches to allow sufficient bend. They looked beautiful but were probably fiendishly expensive and short lived. In his later years Frank turned right off wing masts and tried to get the Tasar class to dump their wingmasts in favour of round carbon tubes.

    Years of practical experience have demonstrated how over-rated wingmasts are in dinghies. They have been tried in many development classes and usually fail. They work in cats where sail shaped and stability characteristics are different, but even there it's interesting to see how minute the difference is between blunt "semi wing" sections (a la Hobie Tiger) and much more efficient looking "super wing sections" (a la Capricorn). In the world's most popular wingmasted sloop mono, getting the wingmast working properly compared to just sticking it in the middle seems to make only about as much difference as having the jib lead 2 1/2" out of position.

    I could never work out why the performance of wing masts never matched the theory in monos. Then I had a good look at the studies of Marchaj and others and saw how disproportionately huge the masts they tested were, and how crude and twisted their test sails were. The more recent work in CFD also indicates that the old theories were wrong and that reality is right.
    Last edited by Chris249; 07-08-2017 at 07:02 AM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Chris, thanks for showing up for the discussion. I know you have a wealth of experience and knowledge of sailboat racing that certainly could be helpful in the development of my design. It would be great if you could stop by St. Augustine sometime and we could just go sailing on Bernadette and you could see and feel exactly what the birdwing mast may have to offer.

    By far the most difficult aspect of the design to appreciate is the balance. Because it lunges forward before it sweeps aft as it faces the wind direction, even though it has length along the airflow, it has such low mass and is so well balanced, that it takes very little energy to make it face the direction of the wind. It rotates on a plastic piece and is surrounded by a plastic bushing as it emerges from the mast step. That's all the help it needs to freely rotate to face the wind direction under bare pole. Yes, there are moments when the wind direction changes and the birdwing feels the need to adjust itself and does so but the forces involved are so tiny that it certainly does not affect the boat's direction or set of anchor. In that respect it acts much more like a conventional mast than a wing mast.

    The next thing I'd like to point out is there is nobody on this planet who would like to know more about the birdwing mast design than me. At this year's WoodenBoat Show I spent an evening talking very loudly to my friends across the table from me because the restaurant was so loud. The next day, I spent the entire day talking to people about the mast and the boat and by the end of Saturday, my voice was completely gone. I spent all day Sunday sitting under a dining canopy away from the boat so that I would not have to talk to anyone. This turned out to be a blessing in disguise. I had never sat all day long 10' from Bernadette's stern just watching the birdwing mast adjust to changing conditions. You get a perspective of the design that you simply do not get while sailing the boat. It was a very educational day. I occasionally adjusted the mainsheet to keep the boom from extending beyond the gunwales of the boat when I could but sometimes the wind so strong that this was not possible. I had moments when I was looking for the trailer wheel to lift off the ground and everything going over so in effect I spent the entire day sailing the boat from a distance where I could see exactly what was happening. I think, Chris, if you had been there and observing from a similar perspective, you would soon realize that the birdwing mast is definitely not a wing mast but it is not a conventional straight mast either. It is a brand new type of animal. With its self-rotating characteristics, its like it has a mind of its own. Whatever you might say about the birdwing design, There has never been a birdwing mast before now. I'm not saying it is the answer to world peace or anything near that but to me, it is definitely a design direction worth exploring further.

    In listening to people react to the birdwing mast, I hear a lot of "that's cool" and "wow, look at that thing!" but the one I enjoy the most is "I wonder why no one else has not thought about that one before" – that one I can answer. Nobody else had a loud, obnoxious, beer-guzzling fishing buddy that forced the creation of a mast that stores along the gunnel and stays completely out of the way of a couple of guys' fishing. The birdwing is one of those strange two-staged inventions that is great for one thing (storage) but may also offer aerodynamic advantages as well. My latest prototype is really the first birdwing mast that begins to explore the aerodynamic issues of setting sail. It took Thomas Edison one hundred tries before he got to Tungsten as a filament material. Bernadette's mast is really the first birdwing mast that I've ever built that even begins to explore the aerodynamic advantages the design may have to offer. At my age, I do not know how many more birdwing prototypes I have in me to offer the design world. In truth, there's nothing I'd like better than to hand the whole thing off to someone more knowledgable and smarter than me and with the means to take the birdwing design to the next level in carbon fiber and see where it goes from there. So far that opportunity has not presented itself so I will keep plugging along with my tiny research budget and continue to entertain myself in my old age.

    Last edited by kenjamin; 07-08-2017 at 07:38 PM.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Rudderless,

    Here's that other picture I was telling you about that shows well the blade-like structure of my latest prototype. It's the same mast that you see from the side in the picture of Bernadette and me at the WoodenBoat Show.


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    Default Re: Birdwing mast design to benefit from new sail track composite material

    As Chris pointed out above, what works (i.e. is most efficient) on one boat does not mean it will work on the next. That is because there is so much more at play in a sailboat than in an aircraft. Add a jib, for instance, and the entire set of "rules-of-thumb" changes for the mast and mainsail.

    Short of actual or windtunnel tests, a cfd study of your design is really the only way to know its true merits and should idealy include every possible variation in configuration (round mast vs profiled mast, flush sail track vs the luff gap left by the ring-sliders etc).
    And remember to add wind gradient and resulting flow twist - especially since your mast will likely exhibit a lot more torsional flex. This could very well be one area where your design has an advantage over a straight rotating wing-mast: in twisted flow and with a twisted sail, the straight mast setting angle is only optimal for one paritcular point along the span.
    Let me know in what formats those CAD models are available, I might be able to help with some of the simulation.

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Whiskeyfox, thank you for your kind offer. I will check with JF Bedard and see what file formats are available. I believe they were done in Rhino, if that is any help.

    It is difficult to describe the level of frustration this patented design has caused me over the years. At one point Florida State University owned 100% of the patent and 60% of the licensing rights of an idea that cost them seven years of effort and over $16,000 worth of patent lawyer fees. At that point, I had thought my job was done. Surely they would do basic wind tunnel testing in their multimillion dollar wind tunnel and they would plainly see the aerodynamic advantages my design (and their patent) had to offer the sailing world. Unfortunately the guy who controlled the wind tunnel was not a sailor and he got extremely insulted when his idea for redesigning my mast did not sit well with me so he threw me out of his office. In fact no one at FSU knew what to think of my design and believe me I searched and I searched. Fortunately for me I complained enough that FSU's solution was to sell it back to me for a garage sale price on a Sunday afternoon at 5pm.

    Fortunately again, not every possible configuration for a birdwing mast needs to be explored. Only the mast as defined by the patent matters to me and for good reason. The patent describes a sickle-shaped mast that has a straight section that rotates in a mast step (the handle) with its round cross section and a curved section in the airflow (the blade) that utilizes an aerodynamically efficient cross section along the entire length of the curved part. So round, square, or oval cross sections are of no interest to me. In spite of illustrations to the contrary, there is also no reason why the straight part need be in the airflow at all. It can be below deck and completely out of the airflow. The curved part of this design has an especially appealing characteristic in that its entire length can present continuous sail setting curvature along its entire length AND rotate in a balanced fashion on the straight section hiding below deck. Not only that, there's no reason the design needs to be limited to a freestanding mast step. A deck mounted stayed mast is also a possibility with the right hardware in place - headsails would need to be attached so that they would not greatly affect the free rotation of the mast but that is not much of a problem either.

    As far as wind tunnel testing is concerned, it would be a huge step in the right direction if a continuously swept back curved mast like mine with an "aerodynamically efficient" cross section could be shown to be more aerodynamically slick than a conventional straight mast of any cross section that sticks straight up in the airflow. It's painfully obvious to me that a swept back curved mast has an aerodynamic advantage in the aerodynamic drag department more than almost any straight mast on the planet. And yes I am in search of an intelligent life form who can point this out with hard data - real or virtual. Either would be great ammunition to use for other continued experiments that could show its efficiency potential for actually setting sail.

    As I have said over and over, the good news is that the birdwing mast is not a wing mast at all. It definitely does not misbehave at anchor. With its swept back shape, efficient cross section and its ability to self-rotate in an extremely well-balanced fashion, it is nearly aerodynamically invisible under bare pole. It sets sail area and strikes sail area the same as any conventional straight mast except that it does so along a curved shape rather than a straight one. To me it's like asking which has a lower drag coefficient, a Honda Accord or a Jeep Wrangler. You really do not need a college education or a wind tunnel to answer that one. Yes, there is a point where too much curvature does not create enough lift for working to windward. But am I the only one on the planet who wants to know what that optimum amount of curvature is?

    Last edited by kenjamin; 07-11-2017 at 06:55 PM.

  25. #25
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Hey Ken-- I've been intrigued by your birdwing mast experiments since you first set it up on Xena (sp?). Have you ever thought about setting up a "GoFundMe" page or Kickstarter? I know absolutely nothing about these crowd-funded quests beyond what I read in the news, but perhaps it's worth it to gather a quick $4k for a wind tunnel test. I'd wager a few people on this site would take a flyer on that. And I bet the fellow who set up your website would know a bit about it. Best of luck!

    --Mike
    “It doesn’t matter how slowly you go -- so long as you do not stop.”
    -Confucius

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Relating to this..."The U.S. patent #8,739, 720 should not affect you in any way unless you were to sell them (or use them) here in the U.S.A. - at least that is my understanding of the situation"

    A patent protects that another entity cannot commercialize the invention. So yes in the US, no one else can sell your invention. But anyone can use it for personal or commercial use. Commercial here doesn't mean selling it, but for example if someone had a sailboat charter business and wanted to make a birdwing mast as described in your invention and use it on their commercial sailboat, they could.

  27. #27
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by MoMan View Post
    Hey Ken-- I've been intrigued by your birdwing mast experiments since you first set it up on Xena (sp?). Have you ever thought about setting up a "GoFundMe" page or Kickstarter? I know absolutely nothing about these crowd-funded quests beyond what I read in the news, but perhaps it's worth it to gather a quick $4k for a wind tunnel test. I'd wager a few people on this site would take a flyer on that. And I bet the fellow who set up your website would know a bit about it. Best of luck!

    --Mike
    Hey Moman, thanks for the suggestion. I looked into that avenue briefly but it was my understanding that they would actually want some return for their investment eventually and being retired and all, I didn't want the pressure to perform. I've turned into a bicycling fanatic in my old age – it takes up most of my time. When you get as old as me, the priority to get healthy tends to rise to the top of the list. It's very tempting for me to just mortgage the house and go at birdwing development full bore. But that would put a major crimp in my well-developed retired lifestyle. Somebody might actually expect some work out of me and in retirement that is to be avoided.

    It's only been about a year and a half since FSU sold the patent back to me and I'm still trying to figure out what to do next. My cousin's husband volunteered to run my website and that was big. So at least the birdwing invention information is now available worldwide. My mentality is that I worked 37 years as a graphics guy at FSU Physics and that's about all the work I want to do. Take out the trash on Wednesday and mow the yard is about all the work I do now. Life is good and I don't want to mess that up.

    For me building Muri-Maru will be fun and sailing it successfully in the Texas 200 would be a dream come true. So try to understand that the priorities of a 67 year old guy are a lot different than someone with a lot more time to spend on the planet. If it ain't fun and cost lots of money, I'm not very interested. I'm optimistic, though, somewhere in the back of my mind I imagine myself finding a sponsor or an investor who would be interested in taking the birdwing design to the next level in carbon fiber but I'm not dying for that to happen, but it would be fun.

    At the big WoodenBoat show at Mystic this year, a guy stopped by my birdwinged boat, Bernadette, and asked me if I would be interested in a virtual reality aerodynamic study on my birdwing invention. I said, "I've been looking for you." But that guy has yet to contact me so I guess that idea is on hold for now. I do however think that is the most logical step in the process for birdwing development and one that may cost little or nothing if I could find the right research institution. When FSU owned the patent I thought that they would utilize their grand resources and wind tunnel to at least figure out what they had a patent on but that was not to be. As it turned out, it would have taken a faculty member to put aside their own experiments and turn their attention to mine. I found that to be difficult to impossible at FSU so it was a major disappointment that to tell you the truth, one that I am still recovering from.

    In my mind the birdwing shape is such a good one that it just needs to be discovered but maybe I'm just too optimistic.
    Last edited by kenjamin; 07-27-2017 at 09:06 AM.

  28. #28
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by jdonahu View Post
    Relating to this..."The U.S. patent #8,739, 720 should not affect you in any way unless you were to sell them (or use them) here in the U.S.A. - at least that is my understanding of the situation"

    A patent protects that another entity cannot commercialize the invention. So yes in the US, no one else can sell your invention. But anyone can use it for personal or commercial use. Commercial here doesn't mean selling it, but for example if someone had a sailboat charter business and wanted to make a birdwing mast as described in your invention and use it on their commercial sailboat, they could.
    I was told by FSU's patent attorney that the patent would cover any use of the invention in USA waters but I'll be happy to let the lawyers fight about that among themselves and leave me out of it. Personally I would welcome the publicity a lawsuit could bring as long as I do not have to pay for it. Seems like I would just need to find a lawyer who's sure they are right and that there's money to be made and let he or she go at it. And I wouldn't mind at all if someone outside the USA would take the invention and commercialize it. That could only be good for me.

  29. #29
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by kenjamin View Post
    ... being retired and all, I didn't want the pressure to perform. I've turned into a bicycling fanatic in my old age – it takes up most of my time. When you get as old as me, the priority to get healthy tends to rise to the top of the list. It's very tempting for me to just mortgage the house and go at birdwing development full bore. But that would put a major crimp in my well-developed retired lifestyle. Somebody might actually expect some work out of me and in retirement that is to be avoided.

    ... My mentality is that I worked 37 years as a graphics guy at FSU Physics and that's about all the work I want to do. Take out the trash on Wednesday and mow the yard is about all the work I do now. Life is good and I don't want to mess that up.
    Do NOT change a thing about your lifestyle! That sounds like the ideal retirement to me. In fact, I plan to model my own life closely parallel to this when I retire in about 27 months (not that I'm counting). Unless there's a global nuclear war or something in the mean time. Perhaps I could arrange a Florida road trip some day and experience your designs in your home waters. Until then, fair winds and happy experimenting.
    “It doesn’t matter how slowly you go -- so long as you do not stop.”
    -Confucius

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    I don't know how they operate at FSU, but when I was a final year engineering student a lot of the available thesis topics involved existing projects with prototypes that needed testing or further development.

    It saved the student a lot of time and money compared to those who chose to design and build something from scratch.

    Testing and analysis is then done with varsity resources and the prototype owner got the benefit of a full report that has undergone evaluation from both internal as well as external supervisors.

  31. #31
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by kenjamin View Post
    It's painfully obvious to me that a swept back curved mast has an aerodynamic advantage in the aerodynamic drag department more than almost any straight mast on the planet.
    Ken, I don't want to rain on your parade any more but I can't help ask - why is it so obvious and what are the advantages?

    Lots of boats can put sweep back in their masts just by increasing pre-bend, but it's not something that makes them go faster per se. And most wingmasted boats have straight masts and measure, very precisely, the amount of sweep back. They find that more sweep back does not make them go faster per se, and often makes them go slower.

  32. #32
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Totally agree that too much curvature can be just as anti-productive as not enough. I have also found that the cut of the sail is every bit as important as the mast. Creating the perfect cut for the perfect amount of curvature in a pre-curved mast is something I know has not been achieved yet. However, Bernadette's sail with her new mast is setting nicely better than anything I've had before in my ten years of testing so I am very encouraged at this point.

    I don't think it helps much to compare bending straight masts and their sail set with a pre-curved self-rotating mast and it's sail set. They are two completely different animals. You also seem to miss over and over again that the birdwing mast is setting balanced sail with a single spar. Try that with a straight mast. You also assume the birdwing mast is in it's final form. It is not. I know much more research needs to be done and state-of-the-art materials need to be applied for birdwing masts to find a place on production sailboats.

    You would be much less frustrated with my enthusiasm for the design if you realize that the birdwing design is in it's infancy even though I've been exploring the design for over ten years. It is only with my latest prototype that I am happy with the sail set and even then it seems to have a less than desirable shape in light air. In heavy air, however, it's looking pretty darn good.



    To spell it out for you here is what I perceive the advantages are or will be when perfected:

    1) Can set balanced sail with a single spar
    2) Quieter and more controlled in a gybe as a result of point 1
    3) Self-rotating at anchor to absolute lowest aerodynamic drag while demonstrating an extremely low drag coefficient for a sailboat mast. It does this without affecting set of anchor because the birdwing is so well balanced, so well shaped, has so little mass and rotates on low friction bushings or bearings. Definitely does not misbehave at anchor.
    4) Tends to store well along gunwale of the average boat due to its curvature.
    5) Looks cool to art majors and bird lovers
    6) Can present well balanced, aerodynamically slick curvature along the full length of mast in airflow.
    7) Should go better to windward better than a non-rotating straight mast in its final computer-optimized form but of course this still needs to be explored and proven as I freely admit.
    Last edited by kenjamin; 07-28-2017 at 10:42 AM.

  33. #33
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Thanks for the reply. From experience with other masts with pre-bend and balance and the geometry, points 1 and 2 would exist but seem to be pretty minimal. 4 and 5 for sure - it's pretty and convenient. But there's still no evidence that what is "painfully obvious" to you about the aerodynamic advantages, and of course that means that there is no way of assessing whether the downsides of a mast with larger chord (such as poor gust response) are compensated for.

  34. #34
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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Quote Originally Posted by kenjamin View Post
    Here she is from the stern...



    Forward cabin has been reduced to a cuddy so that side bench seats can extend far enough forward to comfortably sleep on. In Texas, in the middle of summer, you need to sleep where the air can get to you - cooling is everything. That and the ability to carry lots of ice! Boat will be self-righting, nearly unsinkable, and row-able in a pinch.
    I would have junk rigged that, it would make sail handling so much simpler.
    My take is that if you poke someone with a sharp stick they'll get annoyed, if you smile and shake their hand they will be your friends.

    John Welsford

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    Default Re: Birdwing mast design to benefit from new sail track composite material

    Did FSU intend to make money off the patent? Wouldn't every mast for every size boat need to be custom made in shape, etc. vs. different length extrusions? Maybe they were counting on 3D printing? Major mast builders are going out of business as it is.

    The average bird's wing (like the gulls and ospreys observed) has to fold and that's why they are shaped the way they are, not for aerodynamic reasons, except maybe for diving in a folded position. In the case of the wandering albatross, which stays aloft so much of the time, the wings are as close to straight and narrow as you'd want for aerodynamic reasons, but even they have to fold sometime. Who needs a folding mast?

    I don't understand the notion of masts 'misbehaving at anchor'. Has that ever been a problem for anyone?
    "... and the great shroud of the sea rolled on as it rolled five thousand years ago."

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