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http://www.spacedaily.com/news/rocketsc … SpaceDaily
It looks like it is a very promising tech, but still in its very infancy, the stuff tends to 'self-destruct:'
"Electromagnetic propulsion, which can send an aircraft, satellite, shuttle, bullet or train zooming through the air or along a track, produces extreme temperatures and wear that create quite a challenge for researchers working to make devices that can be used consistently without becoming seriously damaged"
Anyone familiar with this? A 5 mil budget sounds pretty small, will they be able to accomplish anything with this sum?
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"Electromagnetic propulsion" is a fairly ambiguous term. It looks like they are talking about rail guns, though for some reason they have a drawing of an M2P2 vehicle (maybe they just want to be confusing).
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The article talks about a railgun, which is another way of describing linear magnetic acceleration. However, the picture depicts mini-magnetosphere plasma propulsion. I guess the writer or editor is not quite up on his/her science. A railgun uses the same principle as an ion engine, but uses a solid projectile instead of gas; and a railgun uses multiple acceleration stages while an ion engine uses just one. There is a proposal to use a railgun as an engine to move an asteroid, the reaction mass could be hunks of the asteroid itself. Gas or liquid is a lot easier to handle than hunks of solid matter so I don't think a railgun will ever be used as the primary propulsion system on a spacecraft.
A railgun is also known as gauss cannon or linear accelerator. NASA was looking at using it to launch a SCRAM jet aircraft. Personally I think a turbine based engine is more practical since it can take off from any runway, it wouldn't need a magnetic catapult capable of achieving mach 1.
Last time the Navy looked at a railgun they wanted a muzzle velocity of 100,000 feet per second. They did achieve 10,000 feet per second, but not what they were hoping for. Attempts to achieve the higher speed resulted in a supersonic shockwave inside the barrel causing the gun barrel to explode. Why did they want that particular muzzle velocity? Where they hoping a ground based cannon could shoot down a satellite? They wouldn't say what it was for.
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Thanks, I already was wondering what the railgun description was doing there (and i remembered it tends to destroy the gun, so it was doubly confusing.) Guess I pretty much wanted it to be about something else, ignored the reading between the lines.
5 mil for railgun research makes sense, so it's probably just that. Pfff.
At least it's DOD money...
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The United States and Britain and others have been working on rail gun technology for a long time. They want replacements for the large bore main guns that surface combatants are currently using. Gun technology has not really changed in idea since the early 20th century.
Rail guns offer the advantage if working of increased range and impressive damage capability. They also take less room of ammo storage and increased munition safety as they are essentially inert weapons. Other advantages is that they would replace the use of cruise type missiles and are very cheap to fire.
A lot of research has gone into what shape the ammo and cradles will be, not to mention a way to power the magnets that fire the weapon. There is still a lot to do.
Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.
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The United States and Britain and others have been working on rail gun technology for a long time. They want replacements for the large bore main guns that surface combatants are currently using. Gun technology has not really changed in idea since the early 20th century.
Rail guns offer the advantage if working of increased range and impressive damage capability. They also take less room of ammo storage and increased munition safety as they are essentially inert weapons. Other advantages is that they would replace the use of cruise type missiles and are very cheap to fire.
A lot of research has gone into what shape the ammo and cradles will be, not to mention a way to power the magnets that fire the weapon. There is still a lot to do.
Their is alot still left to do, especially when it comes to magnet/power managment but it is mature enought that they are going on the Arleight Bruke class replacement (the DDX) within the next several years.
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Attempts to achieve the higher speed resulted in a supersonic shockwave inside the barrel causing the gun barrel to explode.
Why didn't they use a vacuum in the barrel? I'm assuming that the guns and ammo don't need any chemical reactions.
Waht? Tehr's a preveiw buottn?
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That is the most bizarre thing I've ever read, the editor obviously googled "electromagnetic propulsion" and found M2P2 and just threw the picture up there to make it look pretty, but obviously have have zero connection to one another.
When I first saw this thread, before I even clicked the link I went to both Rob Sheldon's page (Dusty-M2P2), and the M2P2 page which I have bookmarked. Nothing new. So I was really caught off guard.
Pity.
Some useful links while MER are active. [url=http://marsrovers.jpl.nasa.gov/home/index.html]Offical site[/url] [url=http://www.nasa.gov/multimedia/nasatv/MM_NTV_Web.html]NASA TV[/url] [url=http://www.jpl.nasa.gov/mer2004/]JPL MER2004[/url] [url=http://www.spaceflightnow.com/mars/mera/statustextonly.html]Text feed[/url]
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The amount of solar radiation reaching the surface of the earth totals some 3.9 million exajoules a year.
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Attempts to achieve the higher speed resulted in a supersonic shockwave inside the barrel causing the gun barrel to explode.
Why didn't they use a vacuum in the barrel? I'm assuming that the guns and ammo don't need any chemical reactions.
So what happens when the projectile bursts out of the end of the vaccum containment vessle? Would the projectile just destroy itself on the end wall causing the muzzle to explode, essentially no projectile shot further than the muzzle. Or would the projectile burst forth causing sudden reaction with air and a supersonic shock wave, destroying the projectile as it exits the muzzle. You need some way to deal with hypersonic travel. Most bullets travel supersonic, but 100,000 feet per second is mach 91.9! According to MegaConverter 10,000 feet per second is mach 9.19 so that's already hypersonic, but mach 91.9! Can air get out of the way at that speed? How do you get the projectile from muzzle to target?
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Inside a railgun as proposed is 4 magnetic rail loops, the shot is carried in a cradle which is powered by these rails. But as the cradle speeds up it causes a form of supersonic bow wave (shockwave)
This causes the magnetic rails to get pushed away from the cradle and to be damaged. Needless to say the best magnets are superconducting versions and require to be kept very cold, these have proven to be very prone to damage when fired as heating is also inflicted on them.
The damage done to the rails assuming if it does not stop the shot will cause inacuracy and considering the plan is to have Supergun ranges with these weapons this has to be sorted. Some munitions fired have been fitted with guidance type fins which with a small inbuilt gps system allows themselves to guide onto the target.
Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.
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So what happens when the projectile bursts out of the end of the vaccum containment vessle? Would the projectile just destroy itself on the end wall causing the muzzle to explode, essentially no projectile shot further than the muzzle. Or would the projectile burst forth causing sudden reaction with air and a supersonic shock wave, destroying the projectile as it exits the muzzle.
Well at least it doesn't then destroy the multi million dollar costing gun each time you want to fire it during testing.
But perhaps heating the air just outside the gun, so that the air is thinner and slowly gets thicker until 1 atomosphere the farther away (talking about feet/meters). Or else ionizing the air and atrack the air with an anode and a kathode. Ultimately I think of something like a plasma gas just outside the barrel that is thinner then normal air and will also form a layer/coating) arround the moving projectile for a distance (several feet/meters) and be worn of slowly (by friction) and then the projectile hits the normal air density.
Waht? Tehr's a preveiw buottn?
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http://cougaar.org/frs/download.php/139 … s.pdf]here
This is a technical document about the railguns. I love the comment about how delivering megajoules of energy to a target is likely to 'do something'...
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