Cargo Sailing Ship: a near future reality?

Discussion in 'Boat Design' started by Laurent, May 28, 2014.

  1. Kiteship
    Joined: May 2004
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    Kiteship Senior Member

    This graph is "cooked," as so many are on this subject. When I was in high school, I worked one hour at my part-time job to buy a tank of gasoline for my little POS. Today, still I work one hour for a tank of fuel (different POS, but surprisingly about the same mileage--and gas tank size)

    The difference is, today I'm CEO of a profitable corporation and earn 6 times as much as the young kid who is doing my old job--today--at the same drug store. He rides a bike...

    Dave
     
  2. Petros
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    Petros Senior Member

    well, you live in California, most expensive everything, including gasoline, in the country. it did not used to be that way, I lived there from 1961 to 1986. It had competitive prices, good pay and lowest unemployment in the country. Not anymore, and not likely to change anytime soon.
     
  3. SamSam
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    SamSam Senior Member

    The graph is almost 10 years old, it's pretty useless for anything.

    I'm somewhat impressed that as a CEO you only earn 6 times what a minimum wage high schooler makes.

    http://america.aljazeera.com/articles/2014/4/15/executive-pay-compensationceoworkerratio.html

    That you have the same buying power you had when you were in HS reinforces my theory that "they" constantly adjust wages and cost of living based on giving "us" just enough to keep "us" from open revolt.
     
  4. johnhazel
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    johnhazel Senior Member

    Last edited: Jun 6, 2014
  5. johnhazel
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    johnhazel Senior Member

    BTW Watson your Flettner polar is also based on totally ignoring the induced drag of the finite length rotor. The authors are using 2D theroretical results for lift and drag. And, they use outrageously low coefficient of drag estimate Cd = 0.2 for the rotating cylinder. Using their claim of Cl=12.5 and AR=6 the induced drag coefficient is:

    Cdi = Cl^2/(PI()*Aspect=ratio) = 12.5^2/(3.14*6) = 4.3

    Even using their implausibly low 2D drag value, that gives L/D = 12.5/(4.3+0.2)= 2.8 and we have not accounted for non elliptical lift distribution nor hull interference effect or additional drag resulting from flow separation around the ends of the cylinders.

    So your rotor polar based on a bogus L/D=62.5 rotor is itself bogus as are all claims based on it.
     
  6. rwatson
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    rwatson Senior Member

    Could you advise which Polar is wrong ?

    I have posted several
     
  7. johnhazel
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    johnhazel Senior Member

    Post #53
     
  8. rwatson
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    rwatson Senior Member


    hahahahahaha - you claim MY Polar is BOGUS ?????

    The Polar in post #53 comes from https://www.escholar.manchester.ac....&datastreamId=POST-PEER-REVIEW-PUBLISHERS.PDF

    submitted by Rastapop in support of Kites.

    Have a look on page 367, and then refute the whole study if you want.

    While I cant validate the other polars I submitted, they both came from actual builders of rotor ships, Lloyd Bergeson and Anton Flettner. They would both be inclined to optimise their figures due to vested interests, but their performance figures were a lot better than the ones in this study.

    Anton Flettners were nominally based on actual ship performance.

    Feel free to find you own polars from any study you like, but to call valid studies BOGUS is really funny.
     
  9. Yobarnacle
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    Yobarnacle Senior Member holding true course

    CHING CHING! :D 100 pts.
     
  10. johnhazel
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    johnhazel Senior Member

    Yes I know where they came from. The polars presented in that article are bogus for the reasons I gave in post #52
    , #53, and #65.

    That article of yours illustrates how a "peer reviewed" claim can be totally meaningless.
     
  11. Yobarnacle
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    Yobarnacle Senior Member holding true course

    That's also true.
     
  12. whirlwind
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    whirlwind Junior Member

    Kites are glorified spinnakers on a rope. downwind sails at best.
    Flettner rotors are sails ( they only produce thrust when wind acts upon them, like any sail) and so most definitely sail assist.
    The drag component of the rotor being greater than 1 gives the rotor the ability to efficiently sail down wind as well as point as high as 30 degrees off the wind.
    Power to turn the rotors is 5% of the power delivered to the ship as propulsive force KW to KW.
    Angles of up to 90 degrees off the bow of wind, produces a kite teather angle so far from the ships direction of travel as to require large corrective rudder angles which is effectively acting as a sea break , and costing fuel.
    Rotors can be fully automated.
    Kites are problematic to launch and retrieve ( I have seen it )
    CFD and data gathered by E-Ship 1 show the accepted polars and lift/drag charts to be broadly accurate.
    HFO prices are almost static. Bunker prices are rising due to requirements for Low sulphur fuels.
    Wings and dyna-rig produce Coefficent of lift to a max of 2.5 - a conservative number for a conventional rotor is Coefficient of lift at 8.25.
    Quite accurate Mr R Watson.
     
  13. Yobarnacle
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    Yobarnacle Senior Member holding true course

    The advantage of the rotor is it is nearly automated, potentially completely automated.
    An advantage to commercial vessels where work incurs wages/overtime, and to elderly boaters wanting to use wind power without physical strain. It is not a panacea. Additional forms of propulsion need to be aboard.
    This encourages exploration of other limited propulsion systems which in of themselves can't provide all the vessels needs.
    I have hopes that a combination of new or revived technologies can cover all the propulsion functions, perhaps with zero fossil fuel burned.
     
  14. Yobarnacle
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    Yobarnacle Senior Member holding true course

    One such auxiliary drive that could be used in conjunction with rotors is a hydromagnetic caterpillar drive. I hope to construct one.
    I envision a long horizontal shaft with magnets affixed along it's length in a spiral. It is rotated at slow speed, low torque, by an impeller or turbine/prop, spinning by water flow due to vessels forward movement, Shaft is supported both ends.
    It's rotational speed is something less than the vessels speed through the water.
    Either side of the shaft is a wide (vertically) flexible panel running horizontally the entire length of the shaft,
    It is fitted with pocketed magnets in line with the shaft, so that the membrane magnets both sides are repelled from the center shaft, then 180 degree rotation of shaft, membranes both sides attracted to shaft, (repelled/attracted to magnets fixed on shaft)
    Alternately attracting and repelling as spins the shaft magnets spiraled along the shaft, the two membranes should ripple in travelling sine waves opposed to each other.
    The increased volume then decreased volume between the membranes pumps water in direction of wave travel.

    A rigid panel or parallel shell outside the membranes both sides, protects them, and also provides two additional spaces of increasing/decreasing volume, between the shells and membranes. Pumping yet more water. The membranes and shells have forward and aft inlet/exhausts for the water. Direction of shaft rotation determines direction of water flow through the drive. Shaft could be electric motor driven in port. shouldn't require much power.

    The only torque the electric motor or water powered turbine needs to produce, is sufficient to rotate the magnet bearing shaft. Its the magnets spiraled along the shaft and pocketed on membranes, attracting and repelling each other, doing the work of rhythmically flexing the membranes and thus pumping the water.

    Each revolution of the shaft would translate to a complete sine wave cycle equal to the length of the shaft. Or two or more complete cycles if the magnet spiral wrapped theshaft more than once..
    Pumping much more water and at greater velocity, than the waterflow driving the turbine. Huge pitch swim fins rippling in sine waves under water.

    If it works, combine with Flettner rotors and wind, might achieve speeds equal to engine driven vessels of same design and size..
     

  15. kerosene
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    kerosene Senior Member

    Rastapop - keep on studying and growing up. Being stubborn and loud doesn't make you right.

    Statement is clearly incorrect.

    rwatson's comments about 25 hp power to operation giving 270hp worth of push is also exactly correct. Any reasonable person understands what is being meant by that statement.
    Yes thrust is F*V but its clear that at a certain velocity using 25hp of power gives thrust of 270hp*said velocity. Where as using that 25hp to spin a prop would probably give you 17hp*said velocity. To get all picky about terms after claiming fletner ship is not wind assisted is just making loud noise.

    You are all up on arms how the sails will take over the world (kites) and you seem to flip out when people disagree with you. What you fail to understand is that many people who disagree with you would LIKE TO see them kites towing ships. However from the past experience of the hype (its not new you know) its obvious kites are not that simple as they claim. Showing bunch of pictures from test platforms does not mean a commercially viable yet exists.

    If one does please let us know. I mean one used by cargo carriers for financial benefit - not a "pilot project" or prototype.
     
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