Everything Old is new again - Flettner Rotor Ship is launched

Discussion in 'Boat Design' started by rwatson, Sep 1, 2008.

  1. Dolfiman
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    Dolfiman Senior Member

    Our sketches referred to Savonius type of rotor of which blades can be put in an exact circle for the Magnus use.
    For the amount of energy which can be harvested, it depends from your global assembly rotor + permanent magnet alternator, features of each system, rpm ratio choice, ...., typical equations are presented in this paper :
    http://kho.unis.no/doc/Savonius_windrotor_basics.pdf

    What is new and deserves investigation is the total drag on the turbine in such rotation, as that could be converted in thrust for propulsion (when rear winds).
     
  2. rwatson
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    rwatson Senior Member

    I contacted the head of this project (Professor Stephen Salter) , and found that

    1) The photo is just a graphic design
    2) Further research indicates that the multi ridge, curved profile is less efficient than the "normal" flettner configuration.
     
  3. 1J1
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    1J1 Senior Member

  4. thiseasm
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    thiseasm Junior Member

    Hello to everybody,
    After all are there straightforward equations or method to calculate how much energy the rotor needs for the rotation?
     
  5. rwatson
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    rwatson Senior Member

    Hi. Great question.

    I seem to remember that there were some calculation of the fluid drag of the rotating cylinder, and you might find this if you get Joe Norwoods "21st Century Multihull " Publication, ($15 from Englands https://www.ayrs.org ) Amatuer Yacht Research Society.

    The mechanical losses are going to be specific for every design, and I daresay a good engineer could calculate that for you.

    For a long time, there was an incorrect calculation from a Scottish engineer for many years, that said that the drag was excessive, but subsequent builds have proven the error.
     
  6. thiseasm
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    thiseasm Junior Member

    It seems that the most important factor to evaluate the efficiency of the rotors is not easily accessible. Also, I cannot find any contact details with Joseph Norwood, excuse me for the question but is he alive?
     
  7. rwatson
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    rwatson Senior Member

    No, Mr Norwood is not alive.

    I had trouble navigating the ABYS site too - one page failed to work

    BUT
    I found the book here, near the bottom of the list

    https://www.ayrs.org/booklets/

    This is the email I got back from their secretary a while back

    AYRS Publication No 120 (21st Century Multihulls by Joe Norwood, 2vols) is not available for download, but we can post you a copy for GBP7.00 including surface mail. Airmail to Australia would be an additional GBP3.00.

    If you would like a copy, the easiest way of paying for it is through PayPal, making your payment to office@ayrs.org. If you don't already have a PayPal account, then they will charge your credit card. (They will also I believe take payment in Aus$, and convert it for us)

    Please make sure you give PayPal your full mailing address, as we are required to send it to the address they give us, (which for a card payment will be the address to which the card is registered)

    Thank you and hope to hear form you

    Regards
    S Fishwick
    Editor
    Amateur Yacht Research Society
    --
    email: editor@ayrs.org
    WWW: http://www.ayrs.org
    Postal address: Amateur Yacht Research Society, BCM AYRS, London WC1N 3XX, UK
     
  8. 1J1
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    1J1 Senior Member

  9. rwatson
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    rwatson Senior Member

    Fantastic. This is really interesting.

    It looks like a real trend. Well done.
     
  10. JosephT
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    JosephT Senior Member

  11. 1J1
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    1J1 Senior Member

    Looking carefully at those pics, I see the rotors can travel along the length of the cargo deck, allowing to stow them in one single place so there's less obstruction during cargo operations. Very clever!
     
  12. rwatson
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    rwatson Senior Member

    It makes a lot of sense, but I see they moored with the rotors close to the wharf.

    As a bulk tanker it just needs a suction/load feeder at a few locations, and not have to have cranes to sweep the deck.

    Of course, unlike sails, the rotors thrust vector is largely fore and aft, so there is little tendency for the ship to heel while sailing.
     
  13. 1J1
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    1J1 Senior Member

    Found a closer look at the rotors...

    mv-afros-rotors.jpg
     
    rwatson likes this.
  14. rwatson
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    rwatson Senior Member

    Great shot there.
    It looks like they were retro-fitted of course, and they are offset from the loading bays.

    A great detail.
     

  15. 1J1
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    1J1 Senior Member

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