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Watching a half dozen kitesurfers today, it occurred to me that we haven't really tapped the potential of the wind, as a source of energy, yet.
A 747 uses a lot of fossil fuel to get from continent to continent. This waste of resources could be cut considerably, if the passengers weren't in too
big of a hurry to get from A to B.
A huge kitesail, slung into jetstream winds and anchored to the aircraft could pull a modified 747 (almost buoyancy neutral in air, with large inflatable helium bags built into the skin. This would require a false skin on the aircraft, filled with balloons that can be automatically inflated once in the air.) along at a steady clip of around 200-300kmh. In the event of failing winds, the pilot spins up the motors and flies on as normal. The balloons can be deflated and the gas recompressed, and the kite can be hauled in, or jettisoned into the ocean, with a flotation device and an EPIRB, to be recovered and reused.
If you don't have a good stomach for air travel then this method is not for you.
The Jetstream
http://www.pbs.org/...ence/jetstream.html
Average speed about 90mph. Can reach 300mph in the Winter. Exists somewhere over 20,000ft. [st3f, Oct 05 2004, last modified Oct 21 2004]
Kite airplane
http://www.yellowai.../Tethered_Airfoils/
It works. [django, Oct 05 2004, last modified Oct 21 2004]
[link]
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What gauge string would you need? |
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A 747 with retractable spinacker , for when wind favourable . |
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Can also be used for braking on short runways. |
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And that answers your question about string gauge. |
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When I was in a rinky-dink town, I had some fun with a few kites and an enormous spool of quality string - 7" x 12" with a 1" spool. 1 was a Japanese Fighter Kite - I'd release a 1/2 mile of string and dive-bomb the post office. (Spotters called from a pay-phone to let me know target was acquired). But another kite was made from a split heavy-duty trash bag (with a triangle cut out of it) measuring 3' x 5' and gardening bamboo stakes taped to side-edges. That one, I'd unspool until the kite wasn't visible - and then some. Then I'd go to w*rk, as I let the neighborhood kids reel it in. Took 'em 3 hours to reel it in. Hardly took a dent out of that string which I still have, though... |
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Dang! My next idea was for jetstream flight, but without the plane. This is too similar. Ya beat me to it. - Have a croissant. + |
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If you've watched kitesurfing then you'll understand how this would work. |
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Take-off's a bitch as it takes 12 guys and a half mile of running to get the kite up... |
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//If you've watched kitesurfing then you'll understand how this would work.// |
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Kitesurfing was the basis of my idea, hence the croissant. |
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//12 guys and a half mile of running to get the kite up// |
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I'm curious about the actual takeoff process. How do you get the thing off the ground safely? And what, perchance, happens if you get the plane fifty feet off of the ground and then the wind dies? |
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You wouldn't use it for takeoff, as I see it. It would be deployed once you're at sufficient altitude to access the high wind speeds of the jetstream. I don't see there would be enough wind at ground level to lift a 747, unless you launched in a cyclone or tornado. |
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This is an adjunct to the jet propulsion system, allowing fuel savings on a large part of the journey. |
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Instead of deploying a kite each time you take off, you could take a page from Mars-exploration junkies and simply set up a jet-stream "cycler" kite that would permanently "orbit" in the jet stream. An aircraft would dock with it, shut off engines or otherwise reduce power consumption, and allow itself to be dragged along until it was near destination, then unhitch and fly down to the cornfield. |
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Good thought. That would also save takeoff weight problems. |
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Unfortunately the plane would have to beat (zig-zag) to an upwind destination. |
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How do you propose to deploy the kite *in front* of a plane going (up to) .75 mach? |
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[modular] Or go around the long way. |
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[Don Quixote] Make sure the wind around you is going faster? |
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[Phoenix] That's not going to help - if the wind is going faster than the plane (and presumably coming from behind the aircraft, in the direction of travel) - you're not going to get any lift from the wings. |
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Your flight profile will look like this:
1. Normal takeoff, then climb to cruise speed & altitude.
2. Navigate into jet stream.
3. Shut down engines (passengers commence screaming).
4. Decelerate until relative wind begins passing aircraft (enjoy dramatic views of terra firma).
5. If still airborne, deploy kite.
... |
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Either you’re pulling my leg or there’s a surprising blind spot at work here. Now, if you started with a lighter-than-air vehicle, this could work. The hullaballoon comes to mind… |
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//How do you get the thing off the ground safely?//
Of course, no one ever survives the journey. The crew, knowing that, freely hands out croissants to the passengers. It’s the least they can do. |
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//If you've seen kite surfing you know how this would work// |
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No, a kite requires some form of anchor to keep it moving relative to the wind. The surfer may be moving, but the wind is moving faster. When the surfer is not on the water, the kite is basically a parachute. Extreme example: if you kite surfed off a waterfall, you'd eventually end up vertically hanging under the kite, moving through the wind as you glided toward the ground. Without propulsion or thermals, there is no way to gain or hold altitude. |
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//Without propulsion or thermals, there is no way to gain or hold altitude.// |
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Does it help that the kite is in the jetsteam and the aircraft is not? [thinks] Ah, guess not. You'd have to use a big balloon instead. That should work. Mmmm, yes. |
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Freefall is right, there has to be relative motion to generate lift. With the kite in the jetstream, and the 747 outside, you could maybe make 20-50 miles per hour. It would be slow and tedious as hell, sure, but...
well, there must be some advantage? |
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747?, Your kite, your peanuts, and here is your MP3 player. We'll let Los Angeles know you should be there in 5 days. Please be sure to put on lots of sunblock and enjoy Airsail Airlines, the Ecological Transport Company.
I'm doubtful that even that is possible, though, but I was drawn in by the title. |
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OK, point taken. I've modified the 747 slightly. |
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good link. [st3f]. I mightily distrusted the numbers, but am wrong again. oh crap. I did not pay attention and see that the poster was among the pantheon of the 1/2 B dieties. My next Idea is sure to be overly burned. |
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UB: I'd have put the balloon on the kite, but that's just me. [goes off to post another idea.] |
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...sails lighter-than-air pastry across ocean to [UB]... |
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Civ 0 harnesses the energy of dead plants, such as we do.
Civ I harnesses the energy of a planet, such as your kite would attempt to do.
Civ II harnesses the energy of a sun... hmm... some good posts could be build around that.
Civ III harnesses the energy of a galaxy.
Ad nauseum. |
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Why mess about with a kite when you could just deploy great big sails? Even better, you could use a clipper ship with wings and jet thrusters... |
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And set up big turbines over all the active volcanoes. |
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Nanobots that retrieve tiny pieces of the sun and bring them back with little to no loss in stored energy. |
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you mean like, um... what's the word... sunlight? |
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So this is now a blimp that can jettison the blimp part if the jetstream is too slow? Sounds pricy. But then I've never voted against a blimp idea. |
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In terms of amount of energy, a mole of the sun's plasma would have about 10^20 times more energy than the sunlight captured by an oak tree in an entire year. |
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No, no... Mole, as in the the little fuzzy critters that live just under the surface of the sun feeding on radiation. |
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Photospheric Moles, mind you. Those chromospheric moles are just plain lazy. |
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I think its all the... hydrogen. |
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Which is dangerous when mixed with mexican food. |
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The Mexicans did, after all, invent commercially viable fusion power. Who knew? |
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