Wing jib or sail jib?

Discussion in 'Hydrodynamics and Aerodynamics' started by Roelina, Dec 5, 2016.

  1. Roelina
    Joined: Dec 2016
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Rotterdam

    Roelina New Member

    Hello, we are two naval architecture students working on an "innovative sailing yacht design" project. We want to design a bio/twin-rig trimaran with the main sails as wings. Our idea is to also make the two jibs as wing sails but we can't find any information about whether this optimizes the flow around the main sail or not. The only designs we can find are sail jibs with wings as the main sail.

    So our question: is a wing jib a good idea? And why? Or why not?

    Thank you!
     
  2. mij
    Joined: Nov 2013
    Posts: 90
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    Location: Melbourne

    mij Junior Member

    I can't answer your question, but I have made and sailed a model cat with a wing jib:



    And quite a few mast aft wings, which are a bit like a wing jib:

     
  3. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    I take it you want to have two rigid wings for your rig. What is the objective of using two wings instead of one wing?

    It may not be necessary to have jibs at all. A wingsail can have a leading edge designed to operate at high lift without separation, so a jib that acts like a leading edge slat is not needed.

    A slotted wing flap acts much like a jib and mainsail combination already. For model-scale Reynolds numbers, you may want to use a flap that is >50% of the chord, essentially reducing the main element to being the equivalent of the jib.

    If you intend to use the jib for maneuvering, then it may be separated enough from the main wing that it has little effect on the wing's section characteristics. The sections for the two can be designed individually, and the interaction between them accounted for by a vortex lattice or panel code model.

    I recommend you take a good look at Saildrone. It uses a simple single element wingsail, but the aerodynamic control is very effective. It's possible to use the same kind of aerodynamic control with a flapped wing, either by using independent controls for the tail and flap, or by linking the flap and tail together so they move in opposite directions activated by a single control channel. The ratio of flap to tail motion can be tuned so the wingsail operated near the optimum flap angle across the entire range of angles of attack.

    FWIW, here's a panel code parametric design study of an A-frame twin wing rig for a landyacht:
    [​IMG]
     
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