magnetic propulsion

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why06

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Just curious--<br />has anyone ever discussed magnetic propulsion.<br />It would be simple and inexpensive, especially for launching small payloads into space. Think of this, a large shaft launches a payload riding a magnetic current, like a magna-rail, straight into the air without heavy rockets and the expense of replacing that lost fuel or worrying about the potential danger on the enviroment or trashing up space. would it be practical?<br /><br />If so how would it work?<br /><br />Just curious!---Any comments are welcomed!!! <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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CalliArcale

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Rail-launchers have definitely been proposed, and some have been proposed at a very serious level. They do have some drawbacks, the biggest being that they are committed to either a particular orbital inclination (defined by the angle of the rail itself) or a very large and expensive plane shift maneuver.<br /><br />The most practical proposals seem to put it as a first stage, not the sole means of launch. That is, the magnetic rail launcher flings it into the air on a suborbital ballistic trajectory, then a rocket engine fires to boost it further into the desired orbit. This has the bonus of being able to correct the orbital inclination earlier in the ascent, when it's cheaper to do so (in terms of energy, not neccesarily dollars). <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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mcbethcg

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Another problem is that if they are not being used as a fisrst stage, the peak velocity for the projectile is when it is in thick atmosphere, where they would be enormously slowed and burned.<br /><br />To compensate, the projectile would have to be launched at a much higher speed than orbital speed, or else be very massive.<br /><br />No matter what, there would have to be a rocket on the projectile to correct the orbit. Orbits mostly repeat the same path- without a correcting rocket you would have the projectiles orbit starting on the surface of the earth, and returning eventually to the surface of the earth.
 
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why06

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NOT NECESSARILY-<br /><br />-----iT JUST TAKES A LITTLE BRAINSTORMING<br />Say you launched the sattelite or whatever it is from a sub-orbital blimp, like these ones here http://www.jpaerospace.com/atohandout.pdf than you be at ahigh enough altitude that it should not need a preliminary boost to sustian orbit.<br /><br />I also heard some other companies were developing airships that could lift between 500 and 1000 tons.<br /><br />If both the technolgies were combined it might be able to produce an easily mobile platform that could effectively launch tons of cargo very cheaply-using solar panels to recharge its energy.<br /><br />Even if the airship turned out to be HUGE over time it should pay for itself!!!!!! <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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mcbethcg

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I would bet on building 100 mile high towers supporting a magnetic linear accelerator before I would bet on blimps lifting them to a high enough altitude.<br /><br />These things would have to be HEAVY. The weight would affect the maximum altitude.<br /><br />Besides, the thing would have to actually be outside the atmosphere to be high enough, not merely extremely high.
 
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why06

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I guess so, the wieght would be enormous...<br /> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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tomnackid

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Orbit isn't about altitude its about VELOCITY. You have to be moving at about 18,000 mph to sustain a low orbit (far enough outside the atmosphere to remain stable for a reasonable length of time). Launching a payload straight up out of a cannon will do you no good unlsess its moving at escape velocity (25,000 mph). Any slower and it will just fall back. You need to launch with some horizontal component to put your payload into an orbit. That being said the idea goes back a long way. Arthur Clark proposed using an electromagnetic cannon to launch payloads from the moon and wrote a short story about it in the early 50s (Maelstrom II). In the 70s Gerrard O'Neil and his students did extensive research into a "mass driver"--an electromagnetic cannon that could launch small payloads continuously at high rates of speed in order to put large volumes of lunar material into orbit for building solar power satellites and space colonies. Most of the work has been done for launchng from airless bodies with low gravity, but the millitary has been looking into using various types of cannons--from WWII era naval guns to high tech elctromagnetic "rail guns". I think they actually succeeded in putting microsaellites into orbit with old naval guns.
 
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mlorrey

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I believe Gaetano is back in a new incarnation....<br /><br />You are not experimenting, you are flapping your virtual lips and wasting other people's time. Talk is cheap, go out, learn the science, learn what technologies have already been developed (your 'ionic breeze' is an ion engine, old technology), do the math, and make a reasoned presentation.
 
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CalliArcale

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<blockquote><font class="small">In reply to:</font><hr /><p>Another problem is that if they are not being used as a fisrst stage, the peak velocity for the projectile is when it is in thick atmosphere, where they would be enormously slowed and burned. <p><hr /></p></p></blockquote><br /><br />Yes, I was ignoring that. <img src="/images/icons/wink.gif" /> Some suggestions have placed the launchers on high mountains (which I would think would make them impossibly expensive to build/maintain/use). Others only propose them for use from airless bodies, such as the Moon.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>No matter what, there would have to be a rocket on the projectile to correct the orbit. Orbits mostly repeat the same path- without a correcting rocket you would have the projectiles orbit starting on the surface of the earth, and returning eventually to the surface of the earth.<p><hr /></p></p></blockquote><br /><br />Well, not everybody considers the orbit circularization maneuver to really be the booster's job. It's a perigee raise maneuver. Is that being done by the booster, or by the spacecraft's own propulsion system? Does that count as an upper stage or not? Semantics, I suppose. But you are quite right that you couldn't get a magnetic launcher to insert a propulsionless payload directly into the perfect orbit. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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josh_simonson

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Your cannon could be mounted inside of a ramjet powered aircraft instead of an airship, fired at the top of a parabolic near-space trajectory. That'd get you some extra initial velocity and the inclusion of ramjets would get at least one guy off your back. <img src="/images/icons/wink.gif" />
 
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mlorrey

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Oh, please. Josh, putting a railgun up in the air any higher than on a mountaintop (other than in orbit) is so completely stupid an idea that its like mounting an aircraft carrier launch catapult on an F-14. You are not just putting the cart ahead of the horse, you are putting a whole trainset before the horse.<br /><br />What is worse is that, as you are launching from your railgun in mid-air, the law of reaction says that a large fraction of your energy goes into slowing down the vehicle with the railgun on it, since it isn't that much bigger than the vehicle you are launching with it. When the railgun is on earth, you slow down the earth a miniscule amount. I don't care how many ramjets you put on it, stop being stupid.
 
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rrl2

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Hey, but what if the railgun was was pointed down ward into a tunnel in the sea it couluse the force of gravity a speed boost then the shaft could quickly angle up. the craft could fly out and then maybe some ramjets could turn on and carrry it into orbit.
 
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skyone

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<blockquote><font class="small">In reply to:</font><hr /><p>I believe Gaetano is back in a new incarnation.... <p><hr /></p></p></blockquote><br /><br />I don't believe so.<br />Too articulate. Ideas are more juvenile however.
 
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why06

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Couldn't the railgun simply go around loop until enough force was built up then launch the whatever straight int the air. <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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tomnackid

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It doesn't matter. <br /><br />* For every action there is an equal and opposite reaction.<br />* Energy can't be created or destroyed--only changed from one form to another.<br /><br />So speaks the universe! Try to defy these laws at your own peril.<br /><br />Any energy you gain by shooting the projectile downward just get lost again when you come back up.<br /><br />It won't matter how many times you go around a loop to build up speed. As soon as your projectile leaves the gun it will impart a recoil of equal force on the gun and anything attached to it.
 
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CalliArcale

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Yes, it could. However, you will get more energy losses that way than if you could have a straight track -- plus you'll have the G-forces of the turn around the track in addition to the acceleration, so it could make payload design rather complicated. You'd have to run actual numbers to find out whether or not that's an insurmountable problem; I'm no structural engineer, so I can't help out with that.<br /><br />You will still have to cope with atmospheric losses, of course.<br /><br />I think the best use of a railgun would be an extension of the erstwhile HARP program. (Not to be confused with HAARP, which is completely different.) HARP, the High Altitude Research Program, was a Canadian study into cheaper satellite launch technologies run by the late Gerard Bull. How he came to be the *late* Gerard Bull is a conspiracy story in itself, involving both the Mossad and Saddam Hussein. But the interesting part for now is his time on HARP, decades ago.<br /><br />The idea was to take a very small rocket, far too small to put a payload into orbit, encase it in a sabot*, and fire it out of a cannon. The additional boost from the cannon would greatly increase the rocket's speed, allowing it to acheive a much higher altitude. HARP used Canadian military surplus artillery pieces for their cannons and small Martlett missiles as the projectile. The ultimate objective was to scale it up with bigger missiles and bigger guns until they could acheive orbit. Much to Bull's chagrin, however, the Budget Monster ate the program. His long quest for funding eventually lead him to Iraq, where it evolved into work on the Babylon Gun, an enormous weapon similar to the Nazi's V-3. But he died in mysterious circumstances (probably an assasination) and following the Persian Gulf War, the United Nations seized the gun.<br /><br />* sabot, pronounced "SAY-bow" in English but "sah-BOW" in French, comes from the French word for a type of wooden shoe. It's coincidentally the root of "sabotag <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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why06

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In that case railguns could possibly be used in space elevators if they ever came to pass or could be used to launch weapons..... <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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