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#1
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Sorta a glider, sorta a dirigible
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#2
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Earlier, Stewart Kissel wrote:
http://fuellessflight.com/ Interesting concept being developed on this website. Oh, that's truly a hoot. I just emailed that link to a couple of my engineer friends (ones who don't follow RAS). We're all standing by to see if the three laws of thermodynamics start showing up on milk cartons. Thanks, and best regards Bob K. http://www.hpaircraft.com Bob K |
#3
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"Stewart Kissel" wrote in message ... http://fuellessflight.com/ Interesting concept being developed on this website. This a varient of a concept that has already been used in water. See http://www.apl.washington.edu/projec...r/summary.html |
#4
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As Bob notes, the "second law" says you can't win; the "third law" says you
can't break even. It is very hard to break these laws. Here, the energy required to change buoyancy, considered in the underwater version, is apparently ignored. Just another "perpetual motion" machine. Ed Grens |
#5
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E. A. Grens wrote:
As Bob notes, the "second law" says you can't win; the "third law" says you can't break even. It is very hard to break these laws. Here, the energy required to change buoyancy, considered in the underwater version, is apparently ignored. Just another "perpetual motion" machine. the wiley dirigible designer would hang some solar cells on the back of that beast, and be able to pump air in and out to his heart's content. You could heat and cool the air using the day/night cycle to give you the positive and negative bouyancy. You could probably figure out some way to make it switchable between reflecting and absorbing to allow multiple positive and negative bouyancy cycles in a day. The things big enough that you might be able to use the differential wind speeds on its surfaces for energy, ala dynamic soaring. The point is there is plenty of energy swirling around out there for the grabbing, so no laws of physics need be violated. |
#6
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On Tue, 06 Jan 2004 09:37:45 -0500, nafod40
wrote: E. A. Grens wrote: As Bob notes, the "second law" says you can't win; the "third law" says you can't break even. It is very hard to break these laws. Here, the energy required to change buoyancy, considered in the underwater version, is apparently ignored. Just another "perpetual motion" machine. the wiley dirigible designer would hang some solar cells on the back of that beast, and be able to pump air in and out to his heart's content. You could heat and cool the air using the day/night cycle to give you the positive and negative bouyancy. You could probably figure out some way to make it switchable between reflecting and absorbing to allow multiple positive and negative bouyancy cycles in a day. The things big enough that you might be able to use the differential wind speeds on its surfaces for energy, ala dynamic soaring. The point is there is plenty of energy swirling around out there for the grabbing, so no laws of physics need be violated. Of course. Bear in mind that the only winged submersible proposals I've seen detail in (the one man deep-diver) involved positive buoyancy at all times for safety. It could glide upwards, but used a combo of electric propulsion and its wings to dive. As to this dirigi-glider thing: of course it *could* use solar power to run its buoyancy change system but as described on the website it doesn't. Instead it is planning to use wind turbines to extract that energy during descent (and also wrecking its glide ratio), so its is, as described, just another perpetual motion device. Also note that, unless the buoyancy is reduced virtually to zero during descent and raised to about twice the flying weight during ascent its glide will be very slow due to the minimal potential energy available to drive it forward and at some point as the weight tends to neutral the drag forces will prevent ANY forward motion. Add on the benefit (?) of the symmetric or symmetric flapped wing that's needed for equal efficiency during climb and dive and I think the idea is pretty much a turkey. -- martin@ : Martin Gregorie gregorie : Harlow, UK demon : co : Zappa fan & glider pilot uk : |
#7
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Martin Gregorie wrote:
nafod40 wrote The point is there is plenty of energy swirling around out there for the grabbing, so no laws of physics need be violated. As to this dirigi-glider thing: of course it *could* use solar power to run its buoyancy change system but as described on the website it doesn't. Instead it is planning to use wind turbines to extract that energy during descent (and also wrecking its glide ratio), so its is, as described, just another perpetual motion device. Yea, I didn't get that part. I gave them the benefit of the doubt, and assumed something was "lost in translation". |
#8
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When you click on the link that says "click here to see the aircraft fly",
nothing happens. That says it all! David Starer "Bob Kuykendall" wrote in message ... Earlier, Stewart Kissel wrote: http://fuellessflight.com/ Interesting concept being developed on this website. Oh, that's truly a hoot. I just emailed that link to a couple of my engineer friends (ones who don't follow RAS). We're all standing by to see if the three laws of thermodynamics start showing up on milk cartons. Thanks, and best regards Bob K. http://www.hpaircraft.com Bob K |
#9
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On Tue, 6 Jan 2004 22:34:29 -0000, "David Starer"
wrote: When you click on the link that says "click here to see the aircraft fly", nothing happens. That says it all! Here it workes well... The concept itself is not bad... and will definitely work if you use some solar cells to get a little energy. (BTW: This idea is not new. This design was already described in a humorous story in New Scientist at least 20 years ago). But the speed will be sloooow, not to mention the size of this craft if you'd like to have some payload. Simply using a ship (maybe with sails?) will probably not be much slower, and pretty sure it will be a lot cheaper. Bye Andreas |
#10
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"Andreas Maurer" wrote in message ... On Tue, 6 Jan 2004 22:34:29 -0000, "David Starer" wrote: snip (BTW: This idea is not new. This design was already described in a humorous story in New Scientist at least 20 years ago). And it wasn't new then. The prototype flew in 1863. See John McPhee's "The Deltoid Pumpkin Seed" or do a Google search on Aereon. Tim Ward |
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