rail gun

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yevaud

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Small problem (quoted from the article):<br /><br /><i>And because the projectile will be subjected to <b>up to 45,000 Gs</b> during firing...</i> <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>
 
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MeteorWayne

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VERY small after accelerating to 45,000 G's <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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mako71

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Maybe in future, as our technology evolves, we shrink the size of satellites so small that they could be fired to space with something like those. Yes, the acceleration is huge, so there's also this problem in addition to shrink satellites small (maybe a size of a tennis ball). Another problem is that the projectile would heat a lot because of the friction of the air (and at the same time it would loose its speed, so it needs a great initial speed to get to the orbit).<br /><br />Another usage could be in the space for small satellites or probes to fire them to transfer trajectories?<br /><br />For large objects, I'm somewhat skeptic how to distribute the energy to large cannon to accelerate massive objects as well as how the cannon would stand the forces during firing. Maybe, maybe not...<br /><br />There has been some projects to build a cannon, which could fire objects to ballistic trajectories, like HARP (Hihg Altitude Research Project) and SHARP, e.g. http://www.daviddarling.info/encyclopedia/S/spacecannon.html <div class="Discussion_UserSignature"> <p> </p><p>________________ </p><p>reaaliaika.net </p> </div>
 
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owenander

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The Gs is caused by the rapid increase in speed?<br /><br />My thought was that a larger object than 3 feet (40 lbs) would not accelerate as quickly?
 
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yevaud

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Well yeah, it would, as the linear accelerator would have to be proportionately larger to accomodate it. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>
 
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nexium

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To keep the g loading in reason and the air friction heating reasonable, the rail needs to be several kilometers long and at the top of a tall mountain, or a high altitude balloon supported platform. Neil
 
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tomnackid

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"The Gs is caused by the rapid increase in speed? <br /><br />My thought was that a larger object than 3 feet (40 lbs) would not accelerate as quickly?"<br />--------------------------------------------------------------------------------------<br /><br />Yes the Gs are caused by acceleration--just like being kicked back in your seat when you quickly accelerate a car. If you have less acceleration then you either need a much longer gun barrel to build up orbital speed or you will have a very short orbit that will intersect with the earth's surface--in other words you go up then come down with a splat! <br /><br />Electromagnetic (and even chemical) cannons have been looked into for launching small, hardy satellites--or for launching inert slugs to take down satellites. A.C. Clarke proposed the idea of an elctromagnetic space cannon in the 1940s--that is as a serious engineering concept as opposed to Verne's gun cotton powered "Columbiad" and HG Well's electric "space gun" from Things to Come. Ones that produce low enough accelerations that humans can tolerate will be miles long. Air resistance would take a huge toll over those distances and the problem of building miles of evacuated tunnel large enough to hold a crewed space vehicle are not trivial. The moon with its low escape velocity and free vacuum would seem an ideal place for a "space cannon".
 
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