'Sailing'?? Directly to Windward

Discussion in 'Boat Design' started by brian eiland, Apr 19, 2009.

  1. brian eiland
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    brian eiland Senior Member

    Great story High Tacker,....and I always wondered where the damsl came from ;) ...I thought it might be some 'damn sail' :D

  2. tspeer
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    tspeer Senior Member

    I was present at New Jerusalem Airport when they made the runs. The airplane you see in the beginning of the video was flown in by Richard Jenkins, who is the current holder of the world landsailing speed record. Bob Dill was there, too, as the official NALSA observer and measurement guy. Bob designed and built the yacht that Bob Schumacher used to set the previous landsailing speed record.

    For each run, we'd all pile onto the trailer towed by the service vehicle, and ride beside the craft as it made its run. Then we'd bodily lift the whole yacht with Rick Cavallo in it back on to the trailer to return to the start. It was faster to keep him in the craft than to have him get out and then get situated again for the next run. So we had front row seats for the runs!

    They were doing about 25 kt. I think a conventional landyacht could achieve a similar Vmg, but short-tacking up the runway would make it an interesting contest. The acceleration of Blackbird was slow, so I'm quite sure the landyacht would built up a nice lead before the Blackbird got up to speed.
  3. High Tacker
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    High Tacker Junior Member


    For those who can't quite get their heads around the idea of sailing straight into the wind, who think that if you turn up into the wind you are bound to go backwards, another way to look at a rotary sailing rig on a boat is to think of it as a wind screw. The wind is the screwdriver, the wind turbine is the head of the screw, there is a set of bevel gears at the top of the mast, a drive shaft down through the mast, and another set of bevel gears at the bottom, and then the propellor in the water just aft of the mast.

    The prop tracks in water in the same sense that a wood screw tracks in wood, water being incompressible. Consider a wood screw in a piece of wood. When you place your screwdriver into the slot and turn to the left, the screw WILL come out of the wood. Even though part of the force you are applying with the screwdriver is tending to push the screw back into the wood, the force to the left is much greater AND the screw has mechanical advantage.

    A conventional sailboat, on any given point of sail, is a static system and is the simplest of machines in redirecting force, has the simplest kind of mechanical advantage in that the keel creates a plane, a ramp in the water, that is inclined at an angle to windward. I've already said above that a wind turbine driving a prop has the mechanical advantage of a screw, amounts to taking that planar ramp of the conventional sailboat and twisting it into a spiral, a helix. In other words, the prop makes a screw track in the water, a spiral tack the resultant of which is a straight line upwind. I call it the High Tack.

    The rotary sailing system also takes advantage of other basic elements of mechanics, levers and wheels. The airfoils stationed around the hub of the turbine give leverage to the force of the wind, and useful leverage it is. In a conventional sailboat system, the only leverage is going into capsizing, pushing the boat over, which I'm sure everyone will agree is unhelpful.

    Having said all this, I think that an electric drive, with storage capability, and a smaller turbine, would be much more practical, especially because most boats spend a lot of time sitting idle, and could be storing energy. And of course this would enable powering on when there is no wind. Storing compressed air is another possibility.
  4. Leo Lazauskas
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    Leo Lazauskas Senior Member

    There's no doubt that compressed air can be a very versatile source.
    However, many years ago when my engineering colleague looked at it
    as a way of storing energy from VAWT he found the overall efficiency
    of the process very disappointing. It is efficient for a start, but
    gets progressivley worse as the pressure increases.
    It's not my field, but I'm sure some of the engineers here could do a
    quick back-of-the-envelope calculation to verify that.
  5. P Flados
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    P Flados Senior Member

    Compressing air to high pressures makes it very hot. The heat is normally just wasted energy. Lots of wasted energy!

    If you can recover this heat as something useful, your overall cycle efficiency can go up, but this adds complexity.

    Expanding air makes the temperature drop. Heat exchangers between small expansions to put ambient heat back into your working fluid helps with efficiency, but this adds complexity.

    High pressure storage can be dangerous if you do not have safety devices. This brings in the regulators. Complying with regulations adds cost, complexity and generally a bunch of painful nonsense just so that they can show you who is in charge.

    Getting a wind turbine coupled to a compressor in a way that will allow continuous efficient energy capture over a range of wind speed is probably not hard for a mid sized project, but currently would be a real challenge for a home sized unit.

    I have posted before, that a real advance in a home package would be a combination of fancy electronics for turbine control (along with load control) with super efficient generators and motors. The generator to motor method of transmitting energy opens up a lot of very important flexibility. The goal would be integrating a system to include stuff like air compression for energy storage, heat pumps for summer cooling and refrigeration, compression heat recapture for stuff like winter space heating or hot water heating.
  6. High Tacker
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    High Tacker Junior Member

    To: P Flados

    Yes, of course, elementary. Boyle's Law and Charles's Law, compressing air makes it hot, and heats up the container into which you are compressing it, and then letting it expand, i.e., releasing the compressed air, makes it cold, and makes the container cold. And a guy named Carnot put that cycle together, thereby supercharging the science of thermodynamics and the technology of refrigeration, air conditioning, heat pumps, and all that, as well as the foundation for the explanations of all that happens with energy in general, the equivalence of energy with work, that not only can you not get something for nothing, but, rather, you always have to pay a bit extra, for entropy. Gassing away are we here, yet, and methinks it's still the way to go for enlightenment.

    So, expand on that, if you will. I'm too old to carry out the details, but I imagine that thinking along these lines could lead to the ultimate wind machine, for driving sailboats as well as tools in general, and heating and cooling. Environmentally friendly too, no lead, acid, or other unfriendly substances involved, just simple mechanics and elementary computer controls... uh, and the ability to hold a lot of hot air... or, just let it rip.

    For driving a sailboat, imagine a wind turbine with hollow blades perforated on their leeward surfaces, a strip of tiny holes behind the camber curve, so that the blades can suck air in, thereby reducing the pressure on the leeward side of the blade and thus improving the lift to drag ratio, a la Jacques Cousteau's cylindrical sail. But these blades would have proper airfoil shape to begin with.

    To cause the sucking, instead of Cousteau's diesel-powered exhaust fan, I would have the wind turbine, through bevel gears at the top, drive a shaft down through the mast, the mast being a big, hollow and well-insulated tube, and, mounted on the shaft, a series of propellors, fans, which kick the air along down through the mast and blast it out through air-driven propellors under the water, this air having been sucked in through the leeward surfaces of the turbine blades. Mind you, this will be hot air blasting into cold water, and, blasting through the trailing edges of the propellors, thus, in addition to driving force, it would alleviate any cavitation around the propellors.

    This amounts to a specialized use of an ordinary axial air compressor, not a high-pressure operation, so, no danger of explosion, since we are letting it rip, not trying to contain it.

    Given a bit of wind, say a knot or two, to get the turbine moving, then the airfoils become more and more efficient as air is sucked in and blasted through. Hey, no perpetual motion machine here; it WILL reach a limit.

    When the boat is idle, at anchor or at a mooring, the turbine could easily be diverted to driving a piston air compressor for storage at high pressure, or for generating electricity.

    Addition: I don't mean that the propellors should be only air-driven, rather, air-driven in addition to being mechanically driven, geared like the back wheel of your bicycle, which is able to accept, at any given moment, simultaneously or separately, pedal power and/or gravity power. Although not a mechanical engineer, I suppose that the propellors could be able to accept, separately or together, air power and mechanical power, as well as electrical power, all driven by the turbine, and as energy of the moment or stored.
    Last edited: Aug 6, 2012

  7. brian eiland
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    brian eiland Senior Member

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