Inflated Wing Sails

Discussion in 'Sailboats' started by Doug Lord, Aug 23, 2017.

  1. misanthropicexplore
    Joined: Apr 2018
    Posts: 55
    Likes: 3, Points: 8
    Location: Upper middle Missouri River

    misanthropicexplore Junior Member

    I'm just an armchair theorist, but wingsail theory is a hobby of mine. I suspect part of the problem is that the the entire boat is a system. The sail/mast/ballast/keel/sectional and longitudinal form all work together to do a lot of different jobs. A sail works totally different downwind in light winds (drag formation) than it does beam reach in high wind (lift formation), and the mass aloft has the job of dappening roll and pitch movements. That alone is 4 different jobs: drag, lift, roll dampening, pitch dampening, and you might throw in others. For a wingsail to be all around better, It's not enough for a wing sail to provide ridiculous speed per lb at beam reach, it would have to provide better drag per lb, better dampening per lb, etc. Generally they don't, so they (usually) they aren't a generally better option.
     
  2. Konstanty
    Joined: Mar 2016
    Posts: 76
    Likes: 3, Points: 8, Legacy Rep: 10
    Location: Bydgoszcz Poland

    Konstanty Junior Member

    Here are any changes. I do not know how to get a turn on the third mast ? AC36 section by main sail.jpg
     
    Last edited: Jun 27, 2018
  3. Dolfiman
    Joined: Aug 2017
    Posts: 597
    Likes: 255, Points: 63
    Location: NICE (France)

    Dolfiman Senior Member

    New video with some views of inside the inflated sail :
     
  4. Doug Lord
    Joined: May 2009
    Posts: 15,657
    Likes: 218, Points: 73, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    Great, thanks....
     
  5. Doug Lord
    Joined: May 2009
    Posts: 15,657
    Likes: 218, Points: 73, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

  6. CT249
    Joined: May 2003
    Posts: 1,187
    Likes: 59, Points: 48, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    If the claims made by the creators of that French wingsail are correct, an Opti with a wingsail could beat a Laser Radial upwind and beat a standard Laser upwind in a breeze. Sounds like baloney. If the claims are correct, then fitting a wingsail is about five times as effective as fitting foils to an A Class cat. But we've seen much more sophisticated wingsails in As, and 18 Squares, and they didn't work in terms of making the boats go faster. They also didn't work in Moths.

    Once again, people have come up with wingsail claims that don't pass the test of common sense as proven by over a hundred years of experience, which shows that wingsails are not normally faster - and as top-class aerodynamics gurus with wingsail experience have told us here, there is no reason to think they are intrinsically faster.

    It's a bit depressing that magazines and websites are just pumping out this sort of PR rubbish without asking any searching questions or even pointing out basic stuff that any competent sailing journalist should know.
     
  7. Doug Lord
    Joined: May 2009
    Posts: 15,657
    Likes: 218, Points: 73, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    So Ct249, I guess you've uncovered an evil conspiracy by three apparently reputable companies and an untold number of engineers that have conspired together to release made up false data-is that about right?
     
  8. CT249
    Joined: May 2003
    Posts: 1,187
    Likes: 59, Points: 48, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    No, Doug, and nothing I wrote implied that. What may be happening is that some people believe that aircraft must have more effective foils and therefore a wingsail must always be more effective, and they are not researching enough to see what happens in reality.

    As Tom Speer and Mark Drela have been kind enough to tell us here, a wingsail is not always more efficient and (to quote Tom) "The typical argument goes something like this, "Aircraft wings are more efficient than sails. Aircraft airfoils are thick, double surface sections with modest camber. If a sail has thickness and a double surface it will be better than a single surface sail." The problem with this is that it doesn't take into account the different requirements for wings and sails. Plus, aerodynamic tests and calculations invariably show that for any given design point, a thinner airfoil will outperform a thick one........ a thick section will generally have more drag and less maximum lift than a thin section. The ideal shape for high lift would be a thin, highly cambered airfoil. This is provided very well by traditional single surface sails." As Mr Speer also noted; "There's nothing magical about a rigid wingsail. The soft sail rig on USA 17 was faster than the wingsail in some conditions. Whether a wing or soft rig will be faster depends on the class constraints and the sailing conditions."

    Wingsails have been tried for over a century. They have been tried in Redwings, Force 5s, Lasers, Sunfish, Stars, As, Moths, windsurfers, 18 Squares and other classes, time and time and time again. In most classes they don't work for reasons that those who listen to experts like Tom Speer and Mark Drela can understand.

    The people who keep on spruiking overblown wingsail claims are the ones who apparently believe the current experts (like the designers of every racing development class bar one) are getting it wrong when they stick to normal sails. Why keep on ignoring the reality AND the experts who have actually designed winning wingsails? Why anyone would be so disrespectful of the vast majority of the world's best development class designers and sailors is hard to fathom.
     
    Last edited: Oct 30, 2018
  9. Doug Lord
    Joined: May 2009
    Posts: 15,657
    Likes: 218, Points: 73, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    Have you researched the Seawitlab Collective enough to know what their approach is? You seem to dis almost anything that is new from wingsails to foils. You lump together classes where a proper wingsail is prohibited like the Moth(no slot allowed) with failed experiments.The Hall wingsail on the A cat failed because it was too heavy, not because it was a wingsail. Wingsails have been proven in the C Class, AC72, AC 50 and the new F50 cat.
    Some of the inflatable "wingsail" systems may actually offer a simpler rig overall than a "normal" unstayed or stayed rig. The testing and development work being done is great and may result in benefits for all sailors.
    Your description of the Seawitlab Collective story as "PR rubbish" and "sounds like baloney" may or may not be true but then again they may be on to something.
    Seems like you shoot first and don't bother to ask questions. Indicting the companies and engineers involved with the Collective with your special kind of language is not appropriate or fair.
     
    Last edited: Oct 30, 2018

  10. CT249
    Joined: May 2003
    Posts: 1,187
    Likes: 59, Points: 48, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    For you to criticise me for questioning the claims made by wingsail developers AND to also say I "don't bother to ask questions" is just ridiculous and contradictory.

    Yes, wingsails have been proven in a few classes - that doesn't mean the blanket claims made by some developers are true. It's easy to see why they work in some classes but not in others. The French site, however, doesn't say that they will work in some classes, but uses general terms. Furthermore, the claims are obviously exaggerated because even in the classes where wingsails work, they do NOT point 20 degrees higher as claimed by the French site.

    It's not attacking new things when all one does is to look with realism at overblown rhetoric that ignores the reality of the sport of sailing, and my own record of getting into new classes proves that I'm very open to developments.
     
    Last edited: Oct 30, 2018
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.