Posted on 09/19/2005 2:00:34 PM PDT by USFRIENDINVICTORIA
Giant kites that act like sails could bring wind propulsion back to ocean-going ships, reducing emissions and saving on fuel costs
IN THE first half of the 19th century, ships began to adopt steam engines, first alongside and then instead of sails.
{snip} ... the high price of oil and stricter pollution regulations are strong forces working to turn back the clock. Wind propulsion is coming back in a new form: kites, not sails. Next year, SkySails, a German firm based in Hamburg, will begin outfitting cargo ships with massive kites designed to tug vessels and reduce their diesel consumption. The firm estimates that these kites will reduce fuel consumption by about one-thirda big saving, given that fuel accounts for about 60% of shipping costs. {Snip}
But the SkySails approach does away with masts and is much cheaper. The firm says it can outfit a ship with a kite system for between 400,000 and 2.5m, depending on the vessel's size. Stephan Wrage, the boss of SkySails, says fuel savings will recoup these costs in just four or five years, assuming oil prices of $50 a barrel.
SkySails' kites are made of a type of nylon similar to that used in the sails of modern windjammers, but they fly between 100 and 300 metres above sea level, where winds are less turbulent and, on average, more than 50% stronger than the winds that sails capture. An autopilot computer adjusts the height and angle of the kite, the surface area of which can range from 760 to 5,000 square metres. When the wind blows too strongly, one end of the rectangular kite is released so that the kite flaps like a flag. A powerful winch retrieves the kite when necessary.
(Excerpt) Read more at economist.com ...
Just what we need.......cargo ships that can broach. :-)
Okay, but can they tilt the kite so that the lift from the wind blowing obliquely to the direction of travel helps pull the ship? If so, then there would be
an analog of tacking.
Hmm, someone suggested helium: if one filled some of the chambers with helium and others with air, one could get the kite to tilt, making a sideways airfoil like a mainsail. Is there a way to do that within the parameters given in the article?
Details available at http://www.spacealiensarecontrollingmybrain.com.
Sure does. I bet that the software that runs this was not trivial to write.
One advantage of this design is that heeling of the ship in response to wind is minimized.
As I now see was already mentioned.
And when the wind suddenly reverses?
How many of these kites does a shipping company lose before they stop buying them?
I expect few takers for this product, just not that reliable, or cheap!
God forbid they drop a reactor in, and replace the diesels altogether.
That looks like some kind of freaky Dolly Parton lingere.
If it doesn't pan out, at least they could use it as a sea anchor.
All very interesting but the upwind component is just not worthwhile. The vari-trac gizmo is just there to change the kites attitude to the hull, not for tacking. The more the ship is sailing downwind, the closer to the bow the kite is sheeted. Closer to the wind, the kite is sheeted aft.
The kite will not tack. It will collapse. Even if it could tack, it would now have the normal trailing edge (leech) as the new leading edge (luff). It is not a symmetrical foil.
50° to the wind is nothing to write home about. In practice it would be a bear to try to sheet in every puff, lull and oscillation and I would imagine that steering a wide, heavy ship up and down the apparent wind angle would be out of the question.
This thing could have some practical applications but time is still money in the shipping business and wandering all over the ocean will not be popular with shipping agents, port authorities who are expecting your arrival or customers.
Might do better as a liferaft.
That makes a lot more sense - Thanks for showing this. I have one question, what happens when the wind dies and this thing goes into the water, how much of a problem is it to get it back aboard as the ship will pass it by?
The fact that this is (partially) filled with helium (patially) solves the the problem with luff.
That said, I think sticking wings of old DC-10s on the deck with some clever software and adding an adjustible keel would be a better solution.
There are also metal rotating cylinders that can be placed together that work well --- this was the big idea just as steam came along and replaced sails, as you could tack just shy of directly into the wind. Just a few years ago, I saw lots of small boats in the Phillipeans (sp?!) with things that looked for all the world like twin toilet paper rolls spinning where a mast would be --- apparently very useful in shifting wind currents and easy to maintain.
All shipping companies have lowered payroll to the slavewage level.
They'd rather continue to buy black-market crap fuel than pay anyone to fly a kite.
"what happens when the wind dies and this thing goes into the water"
I believe it has helium cells, so it remains lighter than air.
"... what happens when the wind dies and this thing goes into the water,..."
It will be interesting to see how well the prototype the company says they're building will work out in practice. As some others have pointed out, the winds are steadier a few hundred feet up, where the kite would be flown. The rest would be up to the autopilot software. As someone else mentioned, that would not be trivial code.
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