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Post by rmc on May 26, 2014 14:51:18 GMT
arxiv.org/abs/1309.4731medium.com/the-physics-arxiv-blog/98345796bba4www.electric-sun.info/main.htmlFrom these I propose a new type of solar sail: One not dependent upon light, nor the pressure produced from light, as this has a top speed of 10 percent light speed. Instead, I propose an electro-static repulsive filament, like that of a ballooning spider, when used as a sail in space could reach upwards of 25 percent speed of light off the electric sun. These filaments have the potential of being easier to construct than conventional solar sails, as they would simply be extruded lengthways. No complicated array of lines or orthogonal sheets needed.
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Post by the light works on May 26, 2014 15:18:46 GMT
Interesting theories. about 90% over my head, but I can see where it might have an application with the hybrid starship brought up in another thread.
my key question is can you develop and maintain the necessary electrostatic charge in a reliable manner?
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Post by rmc on May 26, 2014 15:28:48 GMT
Interesting theories. about 90% over my head, but I can see where it might have an application with the hybrid starship brought up in another thread. my key question is can you develop and maintain the necessary electrostatic charge in a reliable manner? I think they'd need to confirm that the solar ejecta are due to electrostatic forces first off, as proposed in the Electric Sun paper. If that turns out to be hardcore science fact, then the electro-static propulsion idea would have the same limitations and positive attributes to that of traditional solar wind vehicles currently proposed (though I suspect there are additional benefits with electro-statics... Unless, of course, you end up ultimately just being pulled back into the sun like the ejecta. That would hurt. Doubt that buffs out.). Anyway, the current solar sail gets you up to velocity outbound from a solar system. You coast at velocity toward your destination (though steering seems dubious on solar alone). And, then you decelerate at your destination on the way into your target solar system via same technique in reverse. So, maintaining the charge, solar wind, or light, is really just a thing done near the star to get you going/stopping. |
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Post by the light works on May 26, 2014 15:47:53 GMT
Interesting theories. about 90% over my head, but I can see where it might have an application with the hybrid starship brought up in another thread. my key question is can you develop and maintain the necessary electrostatic charge in a reliable manner? I think they'd need to confirm that the solar ejecta are due to electrostatic forces first off, as proposed in the Electric Sun paper. If that turns out to be hardcore science fact, then the electro-static propulsion idea would have the same limitations and positive attributes to that of traditional solar wind vehicles currently proposed (though I suspect there are additional benefits with electro-statics... Unless, of course, you end up ultimately just being pulled back into the sun like the ejecta. That would hurt. Doubt that buffs out.). Anyway, the current solar sail gets you up to velocity outbound from a solar system. You coast at velocity toward your destination (though steering seems dubious on solar alone). And, then you decelerate at your destination on the way into your target solar system via same technique in reverse. So, maintaining the charge, solar wind, or light, is really just a thing done near the star to get you going/stopping. right. the two critical fails I see are either failing to develop the charge at the other end of the trip, so if, somehow, there was some form of a positively charged sun. as far as the ejecta being drawn back into the sun, is that a charge issue or a gravitational issue? (I.E. is it because the charge lifts the ejecta, but then it comes loose and falls) |
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Post by rmc on May 26, 2014 16:16:00 GMT
I think they'd need to confirm that the solar ejecta are due to electrostatic forces first off, as proposed in the Electric Sun paper. If that turns out to be hardcore science fact, then the electro-static propulsion idea would have the same limitations and positive attributes to that of traditional solar wind vehicles currently proposed (though I suspect there are additional benefits with electro-statics... Unless, of course, you end up ultimately just being pulled back into the sun like the ejecta. That would hurt. Doubt that buffs out.). Anyway, the current solar sail gets you up to velocity outbound from a solar system. You coast at velocity toward your destination (though steering seems dubious on solar alone). And, then you decelerate at your destination on the way into your target solar system via same technique in reverse. So, maintaining the charge, solar wind, or light, is really just a thing done near the star to get you going/stopping. right. the two critical fails I see are either failing to develop the charge at the other end of the trip, so if, somehow, there was some form of a positively charged sun. as far as the ejecta being drawn back into the sun, is that a charge issue or a gravitational issue? (I.E. is it because the charge lifts the ejecta, but then it comes loose and falls) I think, basically, what Dr. László Körtvélyessy is saying in the Electric Sun paper is that the sun has a positive core and a constant negative photosphere. Also, that positive threads can emerge and briefly eject outward against the attraction of the negatively charged surface. The end result is an explosive ejection that is brought back to surface faster than falling due to a positive/negative charge interaction. This seems to follow what is observed (ejecta retracting back into the sun against immense nuclear explosive forces; the same force that keeps the sun inflated). The page of his paper is linked where he explains his point, in case I have it all wrong. |
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Post by the light works on May 26, 2014 18:55:35 GMT
right. the two critical fails I see are either failing to develop the charge at the other end of the trip, so if, somehow, there was some form of a positively charged sun. as far as the ejecta being drawn back into the sun, is that a charge issue or a gravitational issue? (I.E. is it because the charge lifts the ejecta, but then it comes loose and falls) I think, basically, what Dr. László Körtvélyessy is saying in the Electric Sun paper is that the sun has a positive core and a constant negative photosphere. Also, that positive threads can emerge and briefly eject outward against the attraction of the negatively charged surface. The end result is an explosive ejection that is brought back to surface faster than falling due to a positive/negative charge interaction. This seems to follow what is observed (ejecta retracting back into the sun against immense nuclear explosive forces; the same force that keeps the sun inflated). The page of his paper is linked where he explains his point, in case I have it all wrong. my level of physics comprehension will not necessarily accommodate his explanation. |
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Post by silverdragon on May 28, 2014 7:12:55 GMT
This subject worries me.
I have studied Solar Sails on and off for many years, and one problem that always catches, is size.
To get anything like a human sized payload anywhere at any useful speed, it has been estimated a sail would have to be the size of a habitable island?....
The measurements would be in Football fields....
And then, just how far away from a light source would one be useful...
The time it takes to get to that certain speed, would you be out of range of the power source by the time you achieved anything useful in speed?...
And slowing down... obviously reverse, but that could only be done near a strong light source?....
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Post by rmc on May 29, 2014 0:07:29 GMT
This subject worries me. I have studied Solar Sails on and off for many years, and one problem that always catches, is size. To get anything like a human sized payload anywhere at any useful speed, it has been estimated a sail would have to be the size of a habitable island?.... The measurements would be in Football fields.... And then, just how far away from a light source would one be useful... The time it takes to get to that certain speed, would you be out of range of the power source by the time you achieved anything useful in speed?... And slowing down... obviously reverse, but that could only be done near a strong light source?.... All good points. And, chiefly, why electrostatics could be a way out of much of that. |
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Post by chriso on Jun 5, 2014 0:45:39 GMT
Reading that article was painful... Not to be a killjoy, but pseudoscience is a pet peeve of mine. And though maybe some of these conclusions are correct, the majority of the paper is pseudoscience. In fact, some of the data presented contradicts the statement being proven. This looks like a variety of the electric universe theory, a model that has been well debunked. Would be happy to provide some specific examples if asked about how this is flawed. Some further reading on the electric universe theory and the sun: www.abovetopsecret.com/forum/thread665703/pg1neutrinodreaming.blogspot.com/2011/09/electric-universe-theory-debunked.html |
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Post by rmc on Jun 5, 2014 1:15:11 GMT
Reading that article was painful... Not to be a killjoy, but pseudoscience is a pet peeve of mine. And though maybe some of these conclusions are correct, the majority of the paper is pseudoscience. In fact, some of the data presented contradicts the statement being proven. This looks like a variety of the electric universe theory, a model that has been well debunked. Would be happy to provide some specific examples if asked about how this is flawed. Some further reading on the electric universe theory and the sun: www.abovetopsecret.com/forum/thread665703/pg1neutrinodreaming.blogspot.com/2011/09/electric-universe-theory-debunked.htmlWell, that tears it then.. No use waiting around to see if electrostatics ever gets the light of day. Looks like the entire proposal is unfounded. Thank you, chriso. |
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Post by chriso on Jun 5, 2014 6:01:26 GMT
Not quite dead. I should of been a bit more explicit. The article was misrepresenting real data and throwing bogus numbers around, but the data itself was real. (Not that you would be able to tell which is which without training.) The concept of the sun being powered by a electric charge, and having a MASSIVE charge causing most solar effects, is bogus as is the proposed method by which the charge keeps from ripping the sun apart. In reality, if too much charge accumulates, protons repel each other more strongly which is enough to fling the excess protons and their charge out of the sun, balancing the charge. Its a constant and gradual effect. Electromagnetic effects do have real influences in the sun, such as causing sunspots and coronal mass ejections. But the sun isn't powered by an electric charge, nor does it have much of an effect on these events. Its the domain of the magnetic field generated by moving plasma. Anyhow, there is something "electric" you COULD repulse against that comes from the sun. The "solar wind" is a constant, nonstop stream of electrons and protons emanating from the sun that travels throughout the solar system and beyond. If you can interact with this flow, you could definitely generate usable thrust. Ill let you do some speculation. There are a number of ways to do it.  |
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Post by silverdragon on Jun 5, 2014 6:29:49 GMT
The sun "Radiates" a lot of energy, in many forms, radio waves, Light, light invisible to human eyes, and all points between.
Using it to power a space craft would involve collection of energy and using that to create propulsion.
Sailing on the solar winds?...
I propose to do that you would perhaps need to try to orbit the sun for some time until you attain a certain speed and then use that as well as a slingshot effect to get on the move.
That way, you use Gravity as well as other power sources?...
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Post by the light works on Jun 5, 2014 13:44:01 GMT
The sun "Radiates" a lot of energy, in many forms, radio waves, Light, light invisible to human eyes, and all points between. Using it to power a space craft would involve collection of energy and using that to create propulsion. Sailing on the solar winds?... I propose to do that you would perhaps need to try to orbit the sun for some time until you attain a certain speed and then use that as well as a slingshot effect to get on the move. That way, you use Gravity as well as other power sources?... if you are drawing direct thrust from solar wind, you might have a bit of trouble tacking, as a solar sail spacecraft is more a paraglider than a sailboat. - space gives you nothing for your keel to act against. |
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Post by Cybermortis on Jun 5, 2014 14:53:51 GMT
Yes it does - gravity (at least within star systems, which is the only place solar sails would work).
Solar sails would work by providing thrust and counter thrust, lower speeds result in being drawn into a lower orbit around the sun. So you don't really head directly away from a star, rather you are 'sideways' (or the sail is) and travelling in a circle around the star.
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Post by the light works on Jun 5, 2014 15:07:21 GMT
Yes it does - gravity (at least within star systems, which is the only place solar sails would work). Solar sails would work by providing thrust and counter thrust, lower speeds result in being drawn into a lower orbit around the sun. So you don't really head directly away from a star, rather you are 'sideways' (or the sail is) and travelling in a circle around the star. true - the analogies still need a lot of work. I still question whether tacking around the sun would give enough boost in velocity to be beneficial. perhaps a parachute in an updraft would be a better analogy. unless you can design a solar sail to act in the manner of a parafoil, lateral motion in relation to the sun might be of limited benefit. |
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Post by Cybermortis on Jun 5, 2014 17:00:36 GMT
It's not that different to how spacecraft navigate using more conventional propulsion systems, and more or less identical to how craft change the height at which they orbit the Earth. The only difference is that instead of orbiting Earth you are orbiting the sun.
Solar sails are not fast, but they don't require fuel. So if you are not in a hurry they are ideal for intersystem travel.
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Post by GTCGreg on Jun 5, 2014 17:33:21 GMT
If you made your solar sails out of photovoltaic cells, you could then use the electrical power to run gyros to change direction.
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Post by chriso on Jun 5, 2014 18:13:06 GMT
If you made your solar sails out of photovoltaic cells, you could then use the electrical power to run gyros to change direction. I know that a real example of a solar sail uses LED panels that turn black to change direction. A absorbed photon transfers less momentum then a reflected one, so you can change the orientation by darkening a small area of the sail. Also, a photon reflected at an angle will impart part of its momentum to the side, allowing lateral acceleration. And TLW, orbital mechanics can be kind of weird. Lateral acceleration is actually what you want to get to somewhere in a orbit. If you are in an orbit, and you slow down your speed, the orbit gets tighter until the acceleration on the spacecraft equals the centripetal acceleration due to the turn of the orbit. Basically, if you slow down, gravity pulls harder until you move in and your centripetal force balances gravity again. Kind of hard to explain without bringing in lots of technical jargon. The implications of this is that if you can direct thrust in the direction of your orbit, you can move into the system, and by using the different orbital speed go anywhere you want to go. |
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Post by Cybermortis on Jun 5, 2014 19:17:14 GMT
I'd explain it like this;
Imagine that gravity is an elastic band attached to your spacecraft at one end, and a planetary body on the other. The faster the craft orbits the body the further out it gets. The slower it goes the more it gets pulled towards the planetary body.
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Post by the light works on Jun 6, 2014 1:43:23 GMT
I do understand freefall and orbit. we're talking about using a solar sail to leave the solar system. as I understand it, the debate is whether you just (to use sailing technology) run wing and wing on a dead run out of the system, or whether you do a reach on a few laps around the sun to build velocity before setting course to your target.
so my question (and it IS a question) is whether you can actually get similar cross"wind" performance on a spacecraft with a solar sail, as you can with a sailboat.
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