Everything Old is new again - Flettner Rotor Ship is launched

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

  1. DennisRB
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    DennisRB Senior Member

    Stephen has been so kind as to supply an article about is rotor boat that I linked a few pages ago. The small one with the tapered rotor. I hope this answers some of your questions.

    Thanks Stephen. :)
     
  2. rwatson
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    rwatson Senior Member

    Thanks Steve, and for my personal copy too. I would love to see some piccies of the parts and assembly sometime when convenient.

    I am hoping to put a working prototype together in the near future, as, like you, I am intrigued by the concept.

    I think that data indicates a big performance gain using Thom Fences, and that mention you made of self starting vanes is someting I have been considering for a long time.

    Thanks again, and I will be in touch personally very soon.
     
  3. Clarkey
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    Clarkey Junior Member

    From memory (because I can't find the link) Flettner was inspired to investigate rotors at least in part because of the work of Mr. Savonius.

    Savonius built a boat powered by his well known turbines which also develop some lift from the Magnus effect (no propellor was involved by the way). There is a picture floating about somewhere on the net, I know not where. Anyway, there were two problems with this, apparently:

    Firstly, Savonius rotors struggle to reach a circumferential rotation speed of 1.5 x windspeed. This allows them to get towards optimum l/d but not to develop the large lift coefficients that Flettner rotors are generally known for.

    Secondly, a Savonius rotor cannot reverse direction without some complex mechanism for swapping the 'buckets'.

    So a Savonius rotor can be mounted on a Flettner rotor to some effect (some people have postulated that a difference in diameters may give a more efficient setup) but I think on balance Flettner had the right idea - it is better to invest a small amount of motor power to extract more wind power from a simpler rotor. I think he would be extremely happy with the modern development of decent solar panels.
     
  4. apex1

    apex1 Guest

    Ahh, now we are convinced?
    That did sound quite different a few pages back!

    And what makes you think that Flettner was inspired by Savonius?
     
  5. Clarkey
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    Clarkey Junior Member

    Convinced of what? I don't understand your coment.
     
  6. rwatson
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    rwatson Senior Member

    To be candid, I wasnt thinking of anything so esoteric as a Savonius rotor, It could be as simple as fabric "buckets" in flaps under the horizontal gates.

    Think of those flaps in the top of tents to scoop up a cooling breeze - held open by a string, then think of the operation of those "wind cups" on meteorological weather stations.

    I picture a set of these hanging under one or more of the "fences", that can be deployed automatically to provide the starting impetus. As the rotor starts spinning, forward momentum of the boat imparts power to underwater propellor driven (or is that turbine driven) electrical generators, which can then re-charge flat battery storage.

    Maybe they would only get used in rare emergency situations, but it would be great to have the capacity to have "self starting" rotors.
     
  7. julianne2010
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    julianne2010 New Member

    Bergeson is demonstrating the Tracker to fishing-boat owners, talking to large shipping companies, and presenting scientific papers at maritime conferences. And interest is growing. He now has a Navy contract to study the conversion of a military sea-lift ship to rotor-assisted propulsion. He is also conducting similar studies for a number of independent shipping companies, including major oil and cruise-ship companies.


    SeaDream Yacht Club
     
  8. cthippo
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    cthippo Senior Member

    I absolutely love stuff like this. Obviously there is no violation of conservation of energy here, but if you didn't know better looking at one of these things, you could certainly get the impression that there was. Little motor spins tube, wind blows, tube produces more energy than little motor puts in. Looks like free energy until you understand it.

    RE: Commercial applications. It's not a matter of whether it works or not, it's really a matter of how expensive does fuel have to get to make it worthwhile. I'm sure some of you NAs out there have an idea of what it costs to add a bulbous bow to a ship and it took a while for those to catch on as well. This seems particularly well suited to tankers and bulkers where there isn't much movement over the deck during loading and unloading. Probably not as practical for container ships where speed is more of a factor and where access to the deck is critical. I can see these working well for vessels on say the Valdez - Puget Sound run.
     
  9. wardd
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    wardd Senior Member


    seems to me a matter of a small signal controlling a larger signal
     
  10. rwatson
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    rwatson Senior Member

    Thats a quote from an old article over 15 years old (from the Practical Mechanics article I submitted) - Mr Begenson has sinced passed away.
     
    Last edited: Oct 17, 2010
  11. Msf
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    Msf New Member

    Hello everyone

    I'm studying maritime transportation and ship management (deck officer & engineer, Denmark).

    I'm working on a study project about the Flettner-rotor, how to utilize it on tankers or bulk ships on routes crossing the North Atlantic. Method at this point will amongst others be constructing vector diagrams and calculating force with basic equations like F = 0,5 x C x rho x A x v^2.

    The question:

    What Lift and Drag coefficients can be expected at ship speeds around 13-15 knots?

    or can I assume or expect a lift around 10 and drag of 2 (L/D ratio = 5) that some sources states?

    Rgrds
     
  12. EuroCanal
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    EuroCanal Junior Member

    Check post #105. L/D is not fixed - it depends on wind speed. L is proportional to wind speed, the drag of the rotor is proportional to V^2.
     
  13. Squidly-Diddly
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    Squidly-Diddly Senior Member

    how about more of a ring, instead of a stack?

    Maybe on a multi-hull of some sort?

    Maybe a 1 to 5 height to width ratio, where the superstructure WOULD be the rotor, or at least be inside it.

    Sure, I guess you would need to have a ladder to get in and out over the top.

    Just trying to "think outside the stack".

    Maybe go for the Flying Saucer look.
     
  14. rwatson
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    rwatson Senior Member

    Hmmm - interesting look. It would 'work', but maybe not efficiently, as the length of the cylinder provides a great lift ratio. Think of glider wings versus ... not glider wings.

    The closest thing to that concept I can think of is the 'spinning ball airship'

    http://books.google.com.au/books?id...AA#v=onepage&q=spinning ball airships&f=false

    ... a big circumference ball
     

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  15. masrapido
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    masrapido Junior forever

    Since the wind is harnessed for motive power, could it not be also captured to power the rotor? In a suitable configuration of a windmill. Combined with a desired number of solar panels it might provide power for the rotor 24/7.
     
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