Navy Gets 8-Megajoule Rail Gun Working 650
prototypo writes "The Free Lance-Star newspaper is reporting that the Navy Surface Warfare Center in Dahlgren, Virginia has successfully demonstrated an 8-megajoule electromagnetic rail gun. A 32-megajoule version is due to be tested in June. A 64-megajoule version is anticipated to extend the range of naval gunfire (currently about 15 nautical miles for a 5-inch naval gun) to more than 200 nautical miles by 2020. The projectiles are small, but go so fast that have enough kinetic punch to replace a Tomahawk missile at a fraction of the cost. In the final version, they will apex at 95 miles altitude, well into space. These systems were initially part of Reagan's SDI program ("Star Wars"). An interesting tidbit in the article is that the rail gun is only expected to fire ten times or less per day, presumably because of the amount of electricity needed. I guess we now need a warp core to power them."
95 miles altitude is space..Way Cool (Score:5, Interesting)
However, this seems very interesting as an Anti Satellite/"Star Wars" platform. If they can get the software working to intercept, this should (scaled up version) be able to knock out satellites, ballistic missiles, etc - shouldn't it?
I don't see them replacing crusie missles (Score:5, Interesting)
Projectile distortion? (Score:3, Interesting)
What happens to the projectiles in these things? Such a gauss density I would assume, beyond simply the accelleration of the projectile has to be considerable. The coin shrinker is only 1600-2500 J [delete.org]
Assuming 2500 J in a space of 3 mm does to an object the size of a quarter, 8 mega Joules would have an equivilent magnetic density spread over a gun 96 metres in length. Or me math is fscked...
I wonder..... (Score:2, Interesting)
*Meteorites leaves evidence. Meteors can explode in midair.
Cool to think about....
Launch Loop (Score:5, Interesting)
Basically, its a magnetic rail gun for launching space-craft into orbit. And in order to avoid the crushing G-forces involved, it has to be hundreds of miles long. So, while it may not be economically or politically viable, it is technically feasible. We know how to build a launch loop, as opposed to a Space Elevator, which can't be constructed with current technology.
-Sean
Re: 95 miles altitude is space..Way Cool (Score:5, Interesting)
You'd need to build a space tugboat that can hunt down and gather the payloads, then boost them to a higher orbit. No biggy, you can use robots with ion drives for that stuff.
Amount of power (energy really) (Score:5, Interesting)
Heat might be more of an issue. That would be over 30,000 BTUs, or a 60 degree rise in a quarter ton of cooling water.
Re:I don't see them replacing crusie missles (Score:5, Interesting)
Return of the Battleship (Score:3, Interesting)
power not the problem (Score:5, Interesting)
I believe that the time to fire is more likely dominated by the maintenance issues - making sure that the rails are perfectly straight, the warhead is correctly placed, etc. If you're off by even a little bit that sucker could destroy the railgun on the way out, costing you millions and making it inoperative until you're back home.
Re:Replace tomahawk? (Score:2, Interesting)
Re:I don't see them replacing crusie missles (Score:5, Interesting)
Comment removed (Score:3, Interesting)
Re:physics of railguns (Score:5, Interesting)
Re:More nuclear ships? (Score:3, Interesting)
The Navy keeps nuclear power on submarines because the air independence is too valuable (notwithstanding the nuke/diesel arguments) and on carriers because it makes for a ready source of steam (think catapults), hot water, etc.
Power required in electrical form was never really an issue. Modern gas turbines can produce power more quickly and in a denser fashion (think fuel + turbine + cables vs a whole steam engine room) than naval nuclear reactors.
Unless they decide on HUGE engine rooms and prioritize power use, i wouldn't see nuclear powered sruface ships coming back.
Re:I don't see them replacing crusie missles (Score:3, Interesting)
"they will apex at 95 miles altitude, well into space."
There are no winds in space. For that matter, the atmosphere thins out considerably before then. If it didn't these long range railguns would be pretty useless because most of the kinetic energy would be lost. And at the velocities we are considering the time spent in the deeper atmosphere is miniscule. Neither do we know how much spin the projectiles will have (a major stabilizing factor). But it's hard to imagine any such simple and fundamental thing would be overlooked by the scientists involved.
Re:I don't see them replacing crusie missles (Score:3, Interesting)
The GPS-guided artillery shells that I've seen actually don't use "fins" in the same way that a missile does, but little pop-up retarders that change the shape and aerodynamic characteristics of the projectile just enough to produce a change in direction. Allegedly they can be quite accurate.
I think the technology where I heard about the GPS-guided artillery was something to do with the Crusader mobile artillery system. Basically, it was the Army's way of competing with the Air Force as a "surgical strike" capability. Unfortunately then Iraq really happened, and people's interest in surgical air-strikes went out the window with "shock and awe," or at least it seems like it.
Re:I don't see them replacing crusie missles (Score:5, Interesting)
The contract is awarded to a nuclear shop so I suspect that the thing will have an integrated reactor which makes it even more interesting.
What goes around, comes around. After realising that missile tech is too expensive, Iraq tried to build the Babylon gun with a 1000 miles range. For the same reason (the missiles being too expensive) Russians have now developed a gun launcher (forgot the name) to fire high altitude atmospheric probes instead of the old missile system . US nearly did that with the HARP, but heavy lobbying by the aerospace industry killed that. And now we come full circle with US looking at long range guns for cost reasons.
Power is relative, I guess. (Score:5, Interesting)
During a 5-second 'shot', when the stored energy was released, the motor, generator and flywheel would go from 480 to ~100 rpm, and dump 960 mega joules of energy into the coils of the experiment. You could feel the vibration in your feet anywhere you stood at the site, all the CRT's images would collapse due to the intense magnetic field generated. Then it was another twenty minutes before they could do it again.
Useless? (Score:4, Interesting)
I assume a gun like this would go onto a destroyer. I can't think of the last time a destroyer was used in any meaningful way in combat since WW2. If I remember correctly, the only reason the navy even keeps destroyers is because congress forces them to. I guess you could put it on a tank or something, but most conflicts that are fought now are on the ground and are more guerilla tactics than formal engagements. It's being shown in Iraq and Afghanistan that all the fancy new technology that the military keeps buying doesn't really mean squat when it comes to fighting a war.
Am I missing something here?
Re: 95 miles altitude is space..Way Cool (Score:5, Interesting)
alternative to nukes (Score:4, Interesting)
I mean, it's true that nuclear weapons have basically brought peace to modern nations through the principle/doctrine of mutually assured destruction (thats why, for example, all of Europe isn't Soviet Union now -- Russia forced to stop taking over stuff and be peaceful or else get nuked).
Maybe a new doctrine of mutually assured destruction through the crushing of cities through colossal projectiles with ungodly kinetic energy would still provide the umbrella of traditional MAD, but without that tiny little problem (which will never go away as long as there are nuclear weapons) of the potential of some lunatic dictator, who cares more about being in power than he cares about whether or not the rest of life on planet gets wiped out by radiation poisoning, getting his hands on nuclear weapon.
Re:I don't see them replacing crusie missles (Score:5, Interesting)
There's nothing wrong with the nuclear reactors we have now; you could easily fit one of them into a destroyer without any problems. I'm sure Westinghouse Nuclear would be happy to draw you (assuming 'you' have a few billion bucks to spend) some plans of how it could be done. Much of the space optimization has already been done, for submarines. There are several basically standardized designs that you could build the ship around, and then plop one in when you got everything else ready. It's totally doable.
The Russians have several nuclear powered ice breakers that aren't much larger than destroyers, and they used to have several nuclear-powered cruisers as well (although I think they've all been decommissioned).
The reason that surface ships haven't been built with nuclear reactors has more to do with the perceived economics of fossil fuels, rather than any real technical limitations. And for that matter, I've seen analyses that show that bulk supertankers could be economically driven by nuclear reactors -- if the NS Savannah was around today, and upgraded to use containerized cargo instead of manually loaded stuff, it would probably make money due to the high cost of bunker and diesel.
If it's really electricity that's the problem with the rail gun, putting a nuclear reactor on a smaller ship wouldn't be more work than breaking out some old plans, or making a long-distance phone call to a retired-engineer's home in Russia.
Re:Platform instability (Score:3, Interesting)
Re:Probably sufficient for a first stage. (Score:5, Interesting)
Re:Return of the Battleship (Score:1, Interesting)
Re: 95 miles altitude is space..Way Cool (Score:3, Interesting)
Re:I don't see them replacing crusie missles (Score:3, Interesting)
Solar won't help with this to any significant degree - at least not anything mounted on a ship. On the other hand, you could theoretically make a bunch of little floating hockey-puck shaped robots that would be just smart enough to connect to one another and had just enough propulsion for the job, that would make a sort of "floating carpet" of solar collectors. When you were done, you'd just command them to separate into strips, and you'd reel them in like a rope.
Re:I don't see them replacing crusie missles (Score:4, Interesting)
Re:How fast is this thing travelling??? (Score:3, Interesting)
The most surprising thing to me was the terminal velocity of a lead bullet--around 80mph. I would have expected higher from such a dense metal.