Windmill or Wind Turbine- powered boats: how many are out there, and are they viable?

Discussion in 'Projects & Proposals' started by Duma Tau, Oct 9, 2006.

  1. yipster
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    yipster designer

    need them, need them, hmm, need some funds much harder :D
    CR water props show some advantages in better propulsiom
    i wondered why i havent seen CR props for a windmill, on airplanes yes
    grip, rpm, torque, stability, diameter etc could be better i figger?
     
  2. Richard Miller
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    Richard Miller Junior Member

    Gyroscopic effects only happen when the rotor is self powered as in a hellicopter, but not as a passive system as in a windmill generator.
     
  3. Lin Olen
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    Lin Olen Junior Member

    Good morning folks.

    1 The term "prop/s" is short for propeller/s.

    2 Counter rotating props neutralize yaw from torque.

    3 Surface piercing props are more efficient and much faster.

    4 Rotating Sails should have broad, symmetric section, low aspect ratio blades with a reflexed trailing edge and should be free to rotate about the lift axis.

    When I could not get financial or technical aid to install my variable pitch propeller on Thrippence I had remove all of my experimental gear with its hydraulics and sell my boat.

    Converting my 6 foot windmill into a 3 bladed test bed I mounted it on the mill tower as a proof of concept. The rotor began to turn in a gentle breeze and it adjusted itself to handle strong winds with no problems. This experiment was left running for several months.

    This experiment proved that wingtip feathers on birds are a lot better than the latest propeller technology. The concept was offered to propeller manufacturers but those I approached already knew all there was to know about propellers and brushed me off... The same thing happened with my Tuned Hull.

    Being a heretic is a lonely life... Cheers, Lin
     
  4. Lin Olen
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    Lin Olen Junior Member

    "Got no money, Got no friends... ??? "
     
  5. Lin Olen
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    Lin Olen Junior Member

    Not true. My low speed model sailing yacht was stabilized by its Rotating Sail-flexible-drive- marine screw combination. Broaching 3 inch waves while heading directly up-wind without pitching looked very impressive on the 18 inch model. Cheers, Lin
     
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  6. Guest625101138

    Guest625101138 Previous Member

    Lin

    On point 1. When we have the combination of turbines (power collecters)and propellers (propulsion devices) it is safer to refer to them as twisted foils otherwise you will upset Windmaster. This then allows for the case where the air twisted foil becomes the propulser and the water twisted foil becomes the power collector when sailing downwind faster than the wind.

    On point 3. Surface peircing propellers are less efficient than the best submerged prop. The best surface prop gets efficiency around 70%. The best submerged prop around 90%. The virtue of a surface prop comes into play at high speed where the reduced appendage drag has a huge bearing on overall performance but this has nothing to do with efficiency of the blades.

    On point 4. Air twisted foils should be designed to maximise power extraction while minimising the force to hold them against the wind. This is quite different to a land based wind turbine where you generally aim to maximise the energy recovery for a given area. I get the best results from a two bladed turbine with maximum chord around 60% of the radius. The tip speed is almost 10 times apparent wind speed - absolutely flying.

    Rick W.
     
  7. Windmaster
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    Windmaster Senior Member

    Point 3:
    Surface piercing props have an enormous yaw since they are pushing on the water underneath and the air above does not have the same density. I tried one once. To neutralise this yaw you would need two with opposite rotation.
    Point 4:
    This is quite a good idea, but practically, you have got to think what you would do when you wanted to stop them turning. A brake would be the only answer and this would put a huge strain on the system in a gale!

    Rick:
    The turbine and propeller roles would certainly be reversed if you were sailing downwind faster than the wind. Whether this is possible on water no one is sure, but of course it has been done on land as is shown in the famous video which appears on youtube "DDWFTW" (or something like that).
     
  8. Guest625101138

    Guest625101138 Previous Member

    It is not that hard to stop them simply by having control of the angle to the wind rather than allowing weather vaning. Some commercial wind turbines are using this principle to depower. The design I am working on uses a Perm PMG-132 motor with a 4-quadrant drive giving it immense torque capability relative to the prop size and easy able to stall the prop. Once stalled the 2-bladed prop has less area than a mast.

    Rick W.
     
  9. Windmaster
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    Windmaster Senior Member

    This is true but Lin said it would be free to rotate on the lift axis, by which I think he meant weather vaning. Is the design you are working on for a boat or a fixed base land generator?
     
  10. Pericles
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    Pericles Senior Member

  11. Guest625101138

    Guest625101138 Previous Member

    The design is for a Solar-Wind boat. I have attached the original concept showing the stern mounted turbine and a further development of the hull that is slightly shorter, beamier and with increased displacement.

    The current design will cruise at 7.5kts with 1.5kW and top speed just under 12kts. Overall length is 12m. The long keel in the latest design carries 280kg of batteries rated at 10.8kWh at 10hr rate. Solar cells are rated at 1.2kW and turbine design for peak power of 1.4kW. Perm motor/generator will be current limited to 4.8kW. The same motor will be used on both water and air twisted foils.

    I have shown a vane in the original concept but I will be able to override the wind vane to park the blades in turbine mode. Blades have a maximum chord of 120mm.

    The canopy over the cockpit is to provide protection from the rotor. I intend to lengthen the cockpit based on improved protection from the rotor. My blades are quite heavy to limit flexing so they build significant energy. The design thrust load on the turbine is less than 200N so overturning moment from the turbine is very low compared with the righting moment.

    Rick W.
     

    Attached Files:

  12. Windmaster
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    Windmaster Senior Member

    Very interesting. I agree with the concept. You need to gain energy from the environment whether it be wind or solar. Such a boat should be autonomous - that is depend as little as possible on outside power supplies.
     
  13. Lin Olen
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    Lin Olen Junior Member

    Hello Windmaster, Exactly my point. Cheers, Lin
     
  14. Lin Olen
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    Lin Olen Junior Member

    My early papers stressed the importance of Rotary Sail blade tip being designed for transonic conditions. I was delighted to discover years later, that the newre attack helicopter rotors have been designed this way... The rotors are easier to drive and noise levels are much less.

    When I speak about efficiency I encompass the whole vehicle. Submerged props need draggy struts to support a draggy marine propellor that has a useless central area of swept disc within the 50% blade radius. You call that efficient? Cheers, Lin
     

  15. Lin Olen
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    Lin Olen Junior Member

    Hello Rick, I wanted to give you some of the results of my early experiments with propellers. The prop shown on your site is not the best way to go. Windmaster understand my reasoning. Keep your propeller in proportion to your power output. I have used and discarded the work of experts like NASA. Use your gut instincts and ignore the "Specialists" I was thrilled to see that you use linear pedal machanism and amazed that you achieved over 10 miles per hour with the proeller you described. Small contra-rotating surface piercing props are the best, but a low aspect edge mounted twisted foil will give you much more thrust than a large diameter high aspect ratio one. Cheers, Lin
     
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