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Boat with aircraft wing

With rigid aircraft wing as a sail
  [vote for,

This boat is ideally suitable for going perpedicular to wind direction. This boat will have many rigid aircraft wings all along its length mounted vertically, and *perpedicular* to boats length, saperated by 2-3 feets. ( Typical sail boats have sails parallel to length) So a 30 foot boat may have 10-15 wings. Wings "upper" curved surface would be towerds front of boat.

This should provide huge thrust. Regular aircraft wings provide lift upward, but these ones will provide "lift" in forward (parpendicular to wind). It will not have any force from pushing sideways, hence less chance of falling sideways, allowing much larger/taller wings. Such a boat can go much faster than wind itself.

VJW, Jan 23 2012

Wingsail catamarans http://www.americas...News/2012/wdouglas/
Currently being used for the Americas Cup regatta. [neutrinos_shadow, Jan 23 2012]


       Rigid wings on boats instead of conventional sails is well baked. I don't think there's any advantage in having 10-15, rather than 1-2.   

       The best non-rigid sails don't have a vastly worse lift-to-drag ratio than rigid wings; there is an advantage, but maybe not as much as you think.   

       A more efficient sail actually helps whatever direction you sail relative to the wind, not just on a reach (close to perpendicular to the wind).   

       There are disadvantages too, of course, such as increased weight and cost, and decreased versatility - it's more difficult, for example, to reduce the area of sail.   

       A rigid wing is a good idea if you want to attempt a speed record, for example, and can therefore sacrifice versatility and optimise your vessel for a particular set of conditions. About the fastest possible sailing boat has 3 sets of rigid foils - one acting as a sail, one as a keel, and one providing lift (under water), all optimised for one particular angle relative to the wind (and therefore asymmetrical). But that's also baked.   

       Oh, and you can't completely avoid a force on any kind of sail or wing in the same direction as the wind; hence there will be a force pushing sideways, and tending to push the vessel over. A more efficient sail will lessen, but not eliminate, that force. About the only way to avoid the heeling torque is to use kites rather than sails - the force is still there, but it can be more nearly in line with the forces of the water.
spidermother, Jan 23 2012

       The baked version uses keel to move forward. Without keel, it will bet pushed sideways. Proposed version will not need keel to go forward. Baked version has the wing parallel to length of boat hence that boat goes forward mainly because of keel. If the wing is parallel to the length, there is no way there could be any lift in forward direction. edit : this comment was posted before edited version of above comment.
VJW, Jan 23 2012

       Err... you really have to learn more about how boats work. Efficient sails and keels operate best at about 5 degrees to the apparent wind or water direction (the same applies to aeroplane wings, hydrofoils, and wind turbine blades). In nearly all conditions, a fast sailing boat experiences a near head-wind. That is why the sails or wings tend to be nearly parallel to the boat. A boat in your configuration will travel very, very slowly; especially without a keel.
spidermother, Jan 23 2012

       okay, but why don't you think that there's any advantage in having 10-15, rather than 1-2. ?   

       Should not the thrust, however small it is, be multiplied by number of sails (10-15) ? Each of the wing is going to get a clean, non-turbulant flow of air.
VJW, Jan 23 2012

       I think it's for much the same reason as biplanes and triplanes became rare. In general, fewer, larger wings or sails is better than more numerous, smaller ones. Small wings have proportionately larger losses due to viscous flow; and short wings have proportionately larger wingtip losses. For the same reason, larger aeroplanes and sailing boats perform better than smaller ones - up to the point where structural issues become more important.   

       Large sailing ships used to have many sails, but that's for practical reasons - it's only practical to deploy a sail up to a certain size, using canvas, rope, wood, and sailors. If you try to make a bigger sail, the canvas and rigging all have to be thicker and heavier, it becomes increasingly difficult to manage, and it's better just to add another reasonably sized sail instead. Likewise, multi-wing aeroplanes made more sense when the materials and construction methods were relatively primitive. They are still a reasonable option if you need a very light, stiff, short-wingspan aeroplane, and don't mind losing a bit of efficiency - hence modern aerobatic biplanes.   

       In summary, small wings - strong; large wings - efficient.   

       So, with modern materials, you should only consider a large number of sails/wings is if the vessel is extremely large, and then mainly for structural reasons. For a fairly wide range of vessel sizes, around 1 to 2 sails works well. Two, apparently, is especially good, as you can exploit the air passing through the slot between the sails to increase the lift of the aft sail, which is at a steeper angle of attack.
spidermother, Jan 23 2012

       This would be more aptly titled 'Boat with Rigid Sail' or 'Boat with Wing-Like Sail'. For one thing, it would have prevented me getting all excited about launching into another anti-Ekranoplan rant. Imagine my disappointment.   

       Vessels with a single, rigid, wing-like sail are already golden-brown and cooling on the sill. One even competed in the Americas Cup a while back.
Alterother, Jan 23 2012


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