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Because railguns are cool, and a railgun shooting out another railgun is cool squared.
Current speed of Voyager spacecraft
http://hypertextboo...7/PatricePean.shtml
[bungston, Mar 24 2010]
Pioneer anomaly
http://en.wikipedia...iki/Pioneer_anomaly
something besides gravity? [bungston, Mar 24 2010]
13 things that don't make sense
http://www.amazon.c...d=1269450795&sr=1-2
my recent lay audience reading about Pioneer anomaly [bungston, Mar 24 2010]
Deep Space 1 could have reached twice that speed.
http://www.grc.nasa...on/past/90s/ds1.htm
[MisterQED, Mar 24 2010]
Your memory recantered, M'lud
Superconducting_20railgun_20projectile
[Ling, Mar 26 2010]
Plasma Rail Railgun
Plasma_20Rail_20Railgun
Everything is possible in space. [bungston, Mar 26 2010]
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On to the idea. On reading about the Pioneer anomaly I wondered how one might quickly send off a few other deep space probes to retest the phenomenon. |
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The iterative railgun is a large orbiting railgun which fires as its payload a smaller railgun. This in turn fires a smaller railgun. Each successive railgun has a mass 2 orders of magnitude less than its predecessor, because m1v1 = m2v2 and so the launching gun will be propelled backwards in addition to the projectile gun propelled forwards. The final projectile will be the probe, which need only send a signal back so that its trajectory can be tracked. |
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The reason for this staged railgun is to very quickly get the payload up to a speed as fast or faster than the Voyager spacecraft, because we are in a hurry, and maybe a thing has to be far from the solar system for this mysterious additional force to manifest. |
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and apart from the opportunity to say "Russian Doll Railgun" which I admit may have its points, you're using a staged approach with short railguns (that have to fire their next iteration as well as the payload) instead of one long railgun because... |
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I don't think you can make a rail gun self-contained, the power supply is bulky. If you could, I don't think it could survive the acceleration or certainly the EM effects. To have any hope what you are looking for is an Iterative Combustion Light Gas Gun, which I guess could work in theory, especially if you make it out of unobtainium, adimantium or something else really light and strong, but you don't need either, what you need is Deep Space 1 with a bigger Zenon tank, see link. (-) |
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MisterQED: Each gun fires only once. The power supply is a charged capacitor. Are capacitors so bulky? The orbiting first stage is big because it has the solar array to trickle charge its capacitor and those of subsequent stages but the first stage does not have to undergo rapid acceleration. |
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One could even mount the first stage on the space station, for added mass. You would need to use the rockets to correct the station orbit after the thing fired, or you could jettison the first stage to correct the orbit. |
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MisterQED brings up a valid point. I also would question the economics and effectiveness of this compared to equipping the probe with solar cells or nuclear power to power an ion drive, or perhaps a solar sail, gently but continuously pushing the craft, causing unlimited acceleration over time rather than a one-shot. |
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Pretty sure the final speed of the probe is no different than putting the same amount of energy into your initial rail gun, may in fact be slightly slower, since recoil is not your friend. |
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/gently but continuously pushing/ |
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the problem is the gently. We don't want to pay 30 million dollars for gently. |
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/same amount of energy into your initial rail gun/
I think there are limitations to how much energy a railgun can impart that have to do with how much current the rails can withstand. Ling posted something about that in a different idea. If he works like Vernon maybe posting his name will summon him. Ling, Ling, Ling. |
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But rail burnout is a function of rail length. And increasing
the rail length slightly on your first gun is cheaper than
building it heavy enough to launch the second, let alone the
cost of building the second. |
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//increasing the rail length slightly on your first gun is cheaper// but a lot less cool. |
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You could get up to that speed using a solar sail, couldn't you? |
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Assuming the multi-railgun concept - each railgun will presumably have a recoil. So either you could use that to help reload the smaller ones into the bigger ones for a second shot, or you could fire them all at once (if that were possible). In the latter case what you'd have would be a sort of extending rail. |
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//limitations to how much energy a railgun can impart// |
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Only superconducting types. There is a limit for current density, I'm afraid. |
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Morrison, in the linked Superconducting projectile idea Ling lays out a rationale for graphite rails similar to what you propose. |
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Actually not. Graphite is not flexible, and the linked idea was a fixed rail. I think the problem with a flexible conductor, fixed to the projectile, is that the conductor must also be accelerated. Plus the forces pushing the conductors apart would be considerable (similar to the force imparted to the projectile, I think). |
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Plus, of course, that it wouldn't work if the current only existed in the projectile (the reaction is from the current in the rail vs. the current in the projectile...). |
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I am not sure one could use recoil force to reload something in space. I suspect that there must be a third fixed substrate which must be pushed against in some way to harness recoil to do work. |
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Even shotguns are not an ideal place to test this assertion, since in a way the shot and expanding gases play the roles of the second and first stages of the railguns in this idea, with the shotgun itself being a relatively fixed substrate. |
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well the first section wasn't bad.... bit difficult reading the rest since it's not there. |
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{story spoiler, look away now} |
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[morrison_rm], I have a problem with the projectiles you're using on the Palace of Westminster (alias "Houses of Parliament"). I believe you can destroy tanks with kinetic-only projectiles, but that has to do with the fact that tanks don't have a lot of redundant void inside them, so any hard object that passes through the middle of a tank is likely to hit something important. |
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With a large building, on the other hand, you're likely to make an entry wound and an exit wound (and probably puncture a few interior walls in the same way), but adding more initial velocity won't collapse or blow up the building; it'll just make the same holes in the first building, and then similar holes in other buildings behind it. This is especially true of a target which is more of a "groundscraper" than a skyscraper. (You might have better luck with the clocktower shot). |
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So, unless the bench of judges is lined up exactly like the proverbial row of ducks, you're going to miss most of them. |
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Better start the motorbike and try again. |
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We find the defendant guilty. |
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The search for an open-ended continuity of life is
a
simple, remarkably selfish drain on resources that
denies our descendants the privileges of existence
that we have enjoyed. And ironically, matter in
my DNA might be recycled atoms from some other
person who lived long ago. I have no more right to
an eternal choke-hold on it than they. That some
remembrance of my ideas, vision, and impact upon
the world outlast me, and that my progeny go on
to dominate the world and establish an entire
nation of descendants dedicated to my honor in
stories and songs of me as their great patriarch,
that is enough for me. |
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Aah, [RayfordSteele], it's not -everyone- that would get to live for ever, only the right sort of people (i.e. me, and people who agree with me). |
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Only bald people would be allowed to live forever.
Hair consumes resources and demands the existence
of eternal hairstylists, who would simply become too
big of bores to deal with for that long. |
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Bummer that. It was rather entertaining writing. |
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I find the idea sound, though I question it's efficiency compared with other cheaper mediums of propolsion. |
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//Are capacitors so bulky?// |
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//You would need to use the rockets to correct
the station orbit after the thing fired, or you
could jettison the first stage to correct the
orbit.// |
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Just send out two thingies, in opposite directions.
Gadulka! Problemo solvato. |
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Even better, if you did fire two of these things in
opposite directions then, given the recoils of the
successive firings, all but the final stages would
return to their point of origin so you could have
another go. |
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I am pondering the vector forces acting on a railgun
projectile. It is not like throwing a shot-put where
the shot goes forward and you go the opposite
direction. Would a railgun on castor wheels be
propelled backwards by the shot, or is the opposite
action somehow forcing the rails apart? I know that
the rails are pushed apart by the (?Lorenz) forces but
I do not see how the vectors add up. |
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To get it spinning, would you use rockets? Is there an advantage to this over just putting the rocket on the thing you are going to launch? I think to get something to spin it has to push against something else. |
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