Omnidirectional Fixed Sail?

Discussion in 'Boat Design' started by IvoryO, Sep 28, 2018.

  1. IvoryO

    IvoryO Previous Member

    ((New Version))

    To solve some of the issues with the older version, I backed away from the keel control ...and made it simply a very generous rudder on a central ring.

    I also duplicated the fixed sail to allow for additional wind angles (otherwise it would have been trying to force the sheetmetal to bend). The sails can only be lowered or raised in segments, otherwise it is just about getting the craft pointing in the correct direction with rudders.

    [​IMG]
    1) No more ballast tanks (it seemed that trying to lift up the floating ring from the water would have destabilized the craft too much). The craft will be sitting in the water with the rings as well, making it fairly heavy drag (even with openings along the ring and them not being deep). I suppose you could lesson the impact of the rings by sloping them up on the edges (letting the water attempt to go under and lift).



    2) Duplicated the fixed wing sails to deal with all wind directions, solves trying to handle deformation of the sail (again, steel or aluminum sheeting, making it very cheap and long lasting). Duplicating the sail also allows for the above configuration when going with the wind.



    3) VERY generous twin rudders on rings. This is how it would steer and work to counter the force of the sail (as well as motor support).



    (Older Version)
    So, as an evolution of the central structure I've been using in the recent concepts....I've been trying to sort out the way a sail would work on such a structure.

    [​IMG]

    That got me thinking, what if the sail is actually fixed (and made of sturdier / cheaper material, such as steel or aluminum sheeting). Then just cut into shaped strips to be raised and lowered along poles?

    Since the central structure is a cylinder, it being in front of the sail isn't an issue (air flow goes around).

    The last one I posted had the idea of a long retractable keel being run through a sleeve up the center of the structure (letting it go far deeper for stability than normal, and still letting it access shallower waters).....which means the keel is free / rotateable.

    So....why not rotate that instead of the sail? (Though I'd guess it would have to be larger than shown here)

    Other ideas would be to carry over the last underwater chamber, but increase the size a bit and make the lower section a ballast tank. This would ideally give you enough to lift the dock / flotation ring out of the water for travel (so you aren't dealing with the extra drag).
     
    Last edited: Sep 29, 2018
  2. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    A cylinder in the air is one of the worst shapes for airflow, it causes separation and lots of drag - at any realistic wind speed.

    Your sail shape is "poor" also.
    Sails don't use this shape because it doesn't develop good lift to drag.

    You really ought to do some studying before you show this stuff.

    Just because you learned to draw simple shapes doesn't mean its useful for anything.
     
  3. IvoryO

    IvoryO Previous Member

    It is actually the best shape given an omnidirectional goal. Would you prefer a square box? Haha

    What are you talking about? The shape of the sail wasn't just the circular platform extruded up. Could it be optimized? Of course, this is just roughed in.

    [​IMG]

    I'd say the same about your typing.
     
  4. JSL
    Joined: Nov 2012
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    JSL Senior Member

    Wonderful: Sails of steel mounted on a buoy. Should make a good radar target until it capsizes.
     
  5. IvoryO

    IvoryO Previous Member

    I think the sheet of metal sails wouldn't work out. Instead just a square of normal sail material.

    Capsize risk though? How would it tip? With the extended keel you are getting a heck of a lot of leverage and lowering the center of mass....that, and the steel under water hull (above water you could do a lighter material). The thing seems like it would be fairly heavy....and that is before the ring around it (which should ideally be able to float the thing if the entire hull under water becomes flooded).
     
  6. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Spherical balloon would be simpler and still omnidirectional. Teardrop shaped balloon spinning free on a pole would be more efficient? What is the purpose of this craft?
     
  7. IvoryO

    IvoryO Previous Member

    Humm, which part for the spherical balloon? More complex shapes seem less simple to achieve. I've been thinking maybe not doing a fixed sail and instead putting it on a ring / track (so you could move it around). Then extend out the bottom portion to give it a better water profile....giving it a "forward" and a solid large rudder.

    The craft is for sailing around and general purpose as other sailboats. Remote locations and leisure / safety. Ideally the extended keel and ring would give it great stability (combined with doing mixed materials. Steel hull under the water and a steel framed + plywood / epoxy upper structure).
     
  8. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    PC: The balloon would be the omnidirectional sail. It could be inflated to various degrees to control thrust or even deflated completely, in the case of a storm.
     
  9. IvoryO

    IvoryO Previous Member

    Hmmm, that doesn't seem like it would be capable of providing thrust in a crosswind.

    I have an idea of how to move the design though. I've been thinking too traditionally.
     
  10. portacruise
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    portacruise Senior Member

    I got the impression that you had worked out Crosswinds by using some kind of steering with the lower unit?
     
  11. IvoryO

    IvoryO Previous Member

    How does a balloon shape generate side force though? Without that, the balloon sail is just going with the wind.
     
  12. portacruise
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    portacruise Senior Member

    No Info was given that it is a speed or efficiency thing, and it doesn't look like one. I thought you're rotating underwater Kiel would allow for tacking, be it at very low efficiency. If you want better performance, the balloons could be shaped like fixed wings or some other experimental permutation. But then more complex control is needed as in a regular sailboat, compared to Omni directional.
     
  13. Squidly-Diddly
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    Squidly-Diddly Senior Member

    WTF is this thing supposed to do exactly? Is it supposed to sail in some direction or use the sail to generate power or what?

    The guy that invented the Bag Pipes....what was he really trying to make???
     
  14. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Omnidirectional sail is different from an omnidirectional travel. So if you want Omni directional travel, a shaped sail is required, -a spherical balloon shape would not work, except in the downwind direction. A cat design could be used for the boat part which is favorable in shallows, no complex keel needed. A small separate section of the balloon could be deployed at the end of a mast, to keep the cat from capsizing in Stormy Weather.
     

  15. PNW sailor
    Joined: Nov 2017
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    PNW sailor Junior Member

    I fear you're just going to end up like the sailing jellyfish.
    On the downwind beach.

     
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