h a l f b a k e r yIncidentally, why isn't "spacecraft" another word for "interior design"?
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Most of us are familiar with the concept of Foucault's Pendulum; a pendulum on a long wire whose direction of swing changes, driven by the spin of the earth. It is not necessary for the pendumum to swing for this rotation to happen; the pendulum swinging is just a handy way of illuatrating that it is
rotating (actually the earth is rotating and it's plane of rotation is staying still).
Foucault's flywheel would be a huge weight (several tonnes at least) suspended on a vertical shaft that is free to rotate. The shaft is connected to a gearbox that changes the slow spin of the huge weight (1 rotation every 36 hours in mid-latitudes) to the rapid rotation of another shaft (whatever speed is optimum for a dynamo).
Result: The earth's spin is slowed a little, but with a rotational kinetic energy of about 2.5x10^29 joules (back of envelope calculation) I don't think we have to worry about that just yet. Now, where can I get a 99% efficient gearbox with a ratio of 1:130,000?
Foucault's Pendulum
http://en.wikipedia...ucault%27s_pendulum
from the wikipedia. [st3f, Oct 04 2004, last modified Oct 21 2004]
Coriolis Force
http://en.wikipedia...wiki/Coriolis_force
(The thing that makes Foucault's pendulum spin) from the wikipedia. [st3f, Oct 04 2004, last modified Oct 21 2004]
Rotational Energy
http://en.wikipedia...i/Rotational_energy
from the wikipedia. [st3f, Oct 04 2004, last modified Oct 21 2004]
Earth rotation as renewable energy source
http://www.halfbake...e_20energy_20source
globaltourniquet's ideas of using the earth's rotation. [st3f, Oct 04 2004, last modified Oct 05 2004]
Gear head
http://www.harmonic...port/principals.htm
Standard is up to 1:160 in a single step, but they can do higher for wind power applications [kbecker, Oct 04 2004, last modified Oct 21 2004]
US patent 5,313,850
http://patft.uspto....13850&RS=PN/5313850
Earth/gyro power transducer [xaviergisz, Nov 15 2006]
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Annotation:
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How about getting some really efficient inductors and just using the pendulum, taking advantage of the Earth's magenetic field? |
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//Now, where can I get a 99% efficient gearbox with a ratio of 1:130,000?// |
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You check out Wal-Mart yet? |
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//I don't think we have to worry about that just yet.// |
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I'm rather concerned with your callousness on that issue. That's probably the same thing they said when they realized that burning petroleum would cause pollution. Do you really want our descendants to live in a world where the days drag on for 25 hours? |
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You still need something connected to the weight/shaft that is moving horizontally to get any Coriolis force to produce rotation. |
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I thought you had come upon my idea of a vertical flywheel where Coriolis force would press down the upper side to the right and press up the lower to the left until the disc became horizontal. Of course, being a large gyroscope, precession would result in other movements and loss of energy. |
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The rate of spin of this old ball of rock has already been measurably affected by other energy plants, most noticeably by the 240MW tidal power station that the French built across the estuary of the Rance in the 60s. |
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AO: The reason why I'm not concerned is that compared to the amount of water sloshing about the surface of this fair planet, a few thousand three tonne pendulums are but... erm... a drop in the ocean. What I am concerned about is, once we have abundant clean energy, is that we will be significantly heating the earth by producing and using the energy. |
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FJ: I was trying to get my head around the mechanics and wasn't certain whether I would need linear movement. In the end I decided to wing it. Consider this as a three tonne swinging rotating pendulum. We now need not only the gearbox, but a virtually frictionless universal joint capable of bearing 3 tonnes. |
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phlogiston: I find that surprising given the volume of the oceans. Do you know how big the effect was? |
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I'm also a little concerned about all the sloshing water, st3f. We should try to put as much of it as we can into sealed containers. |
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Here's some good news: the 36-hour figure only applies to pendulums. If you held the gyroscope's axis in a plane perpendicular to the Earth's axis, you can get it down to 24 hours. |
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And I don't think you necessarily need a huge flywheel. A small one spinning really fast in a vacuum, with magnetic bearings should work. But that gearbox is a problem... |
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I am no sure why you are looking for a gearbox? It should be possible to design your dynamo to have a optimum speed the same as the flywheel, but it might have a huge diameter. |
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Sloshing water in the oceans has become a matter of concern to me. I think we should put baffles at the bottom of the ocean to stop this menace. |
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Seems like a good potential source of energy... we can always put it back when we make a big planet eating spaceship.. |
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/virtually frictionless universal joint capable of bearing 3 tonnes./ |
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I'm wondering whether a corollary of this invention is that flywheels with large rotational energy in general should be mounted on a gimbal so that the bearings don't wear unduly because of this effect. |
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If it turns out that Earth's rotation slowing down, due to this kind of extraction or
natural causes like tides, is a problem (though I'd personally prefer longer days),
we can use this idea as a way to put rotational kinetic energy back into it. Now,
is there an analogous idea for bringing the Moon closer again, by making the
tides lead it somehow? |
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…and, if we figure out a way to do that, we can use it
against the Sun to move planets around in the Solar System.
Move Venus outward and Mars inward to make them more
habitable? Move Earth outward slowly to track the habitable
zone's movement? |
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Simpler and easier just to do the same as last time, and move it to a different, younger primary. |
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I'm having a hard time seeing how speeding up or slowing down the rotational speed of the Earth would change its mass in any way which would affect orbital bodies.
I get how increasing rotational rate of a planet could lead to a pyriform shape and the potential breaking-away of a moon-sized chunk... |
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...but how does lesser or greater spin draw that satellite closer?
Just tidal mass? This does not compute for me. |
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I didn't mean to suggest a connection between the two
things, just an analogy. However, I imagine that if you made
a planet spin extremely fast in the same direction as its
moon orbited it, such that the matter it was made of didn't
have enough time to react tidally to its moon's gravity
before being spun past the planet–moon axis, that might
accomplish the moon-closening effect by reversing the
planet's tidal drag on the moon. |
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