Navy Gets 8-Megajoule Rail Gun Working

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."

Comments

95 miles altitude is space..Way Cool

[lecithin]

But I was thinking, is this a possible way to launch orbiting vehicles? I first think no, as the initial force necessary to 'shoot' something into orbit would probably destroy any delicate instruments needed for a working satellite.

  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?

Re: 95 miles altitude is space..Way Cool

[Phanatic1a]

But I was thinking, is this a possible way to launch orbiting vehicles?

No, because when you shoot a projectile, you're putting it into a orbit that intersects the earth. You need some other impulse source to circularize the orbit.

Re: 95 miles altitude is space..Way Cool

[Maximum Prophet]

$1000 to launch 3.2 kilos into space. Damn straight. The price has to come down with volume. You just need to install the thing up the side of a mountain. You don't even need the fins and electronics onboard, just some end of the muzzle steering pushes should be enough to change the orbit the thing arrives in. Use it for fuel, water, and supplies that can take the G's, making it that much safer for the astronauts.
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.

Re: 95 miles altitude is space..Way Cool

[wolfgang_spangler]

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? Ronald Regan suggested exactly that same thing, which is why we have the railgun that was tested.

Re: 95 miles altitude is space..Way Cool

[dmatos]

Just because something gets launched to higher than the arbitrary height we have assigned to "the edge of space" does not mean that it will stay up there. The object has to also be travelling at orbital velocity. At LEO of about 200km, orbital velocity is around 7800m/s, aka ~17,500mph.

Not to say that this gun cannot fire projectiles into orbit, just to say that firing something into space and having it stay there is much harder than just firing something into space.

Re: 95 miles altitude is space..Way Cool

[Anonymous Coward]

Parent recap:

1. *some idea*
2. "use robots with ion drives for that stuff"
3. profit!

Re: 95 miles altitude is space..Way Cool

[Yvanhoe]

Well the most intelligent use of a mass driver I have seen in SF (and envisioned real space projects) is to use a mass driver to send the product of moon or asteroid mining back to the earth. IIRC, it requires more than 100 times less energy to send something out of moon's gravity well than to send it out of earth's, so a shot of 100 tons of titanium a day could well make a moon mining facility profitable.

Re: 95 miles altitude is space..Way Cool

[ceoyoyo]

You can't have a spiral orbit unless you're under power. A projectile will travel a ballistic path -- an ellipse. Elliptical paths have the curious property that if you travel along them far enough you'll end up back where you started. So if you fire horizontally your spacecraft will have part of it's orbit in the atmosphere (which doesn't work so well) and it will come back and hit your rail gun from behind (provided it doesn't hit a mountain). If you fire at some angle above horizontal your projectile's orbit will intersect the ground at some point.

Re: 95 miles altitude is space..Way Cool

[javamann]

'High School Math', mmmm let's see, if Billy has a quarter ounce of pot and six people in his van how many joints can he make before they drive to Mc Donalds for munchies?

Re: 95 miles altitude is space..Way Cool

[p3d0]

Yes, as soon as the moon moves to within 95 miles altitude.

Re: 95 miles altitude is space..Way Cool

[bullshit detector]

so a shot of 100 tons of titanium a day could well make a moon mining facility profitable
Even more profitable would be to make Earth pay you NOT to lob 100 tons of titanium at them per day.

TANSTAAFL

Re: 95 miles altitude is space..Way Cool

[ceoyoyo]

No, it's not. Any unpowered bit of mass will travel in an ellipse, or a parabola if the ground gets in the way. Yes, you have to use the right equation. No, "orbital paths" are not something different than the "natural ellipse" that objects travel in close to the ground. All the unpowered objects in the solar system travel in ellipses. If your projectile has too much energy it will not be in Earth orbit anymore, but orbit the sun instead, still in an ellipse.

You can say that the ability of an object to orbit is determined by the energy only if you want, but an object that has part of that orbit that intersects the ground won't orbit for very long. That's what happens if you fire an unpowered projectile from the surface. It's orbit MUST intersect the firing point, barring some sort of acceleration in flight.

None of what you describe admits a spiral as an allowed orbit.

Re: 95 miles altitude is space..Way Cool

[danlock4]

Why do navel ships have an abundance of electricity? I can come up with some guesses, but it's just hand waving.

Navel ships require an umbilical of some type; electricity is often provided through the umbilical.

;-)

I don't see them replacing crusie missles

[winkydink]

if you can only fire 10 per day.

Re:I don't see them replacing crusie missles

[ackthpt]

if you can only fire 10 per day.

I'd be very careful accounting for winds over a distance of 200 miles, particularly where chinese embassies are located. Must be a hell of a job to be spotter for this kind of weapon.

Re:I don't see them replacing crusie missles

[drinkypoo]

Ten a day per launcher, yo. A cruise missile costs a million bucks plus. These projectiles will cost about a thousand dollars (projected, maybe it'll be $2000, still negligible in comparison.) With the amount of money you save not launching cruise missiles, you can afford to build more launchers. Let's say the launcher costs a billion dollars and the projectiles are $2000. You will then "save" $998,000 every time you launch a railgun projectile and you need launch only 1002 projectiles to get your launcher and the ammo for "free". Wikipedia claims the cost of a tomahawk is 1.3 million, so depending on who's right it could be an even shorter period of time. Something like 4500 of these missiles are known to have been made, so assuming an average cost of $1M that's what, 4.5 billion dollars spent so far? Just to put things in perspective. Also, even cheaper munitions could be used for short-range firings where windage will not make a substantial difference and guidance is not needed.

Re:I don't see them replacing crusie missles

[SydShamino]

Well, that's each rail gun that can fire just 10 times a day. Even if they cost $100 million each, there's little stopping the military from buying 50 of them for each coast.

(I'm ignoring whether they are practical or not, or if they cost too much, compared to alternatives. I'm just pointing out that the military can solve many limitations by throwing money at them, and no one in the government is embracing plans to limit military spending at this time.)

Re:I don't see them replacing crusie missles

[dan828]

GPS and computer controlled fins. It'd just be a matter of developing a system that can withstand launch Gs and the electromagnetic forces. Maybe difficult, but probably not impossible.

Re:I don't see them replacing crusie missles

[arivanov]

10 a day is better than ten in total. You will be surprised how few Tomahawks (or Granits in the Russian case) are actually carried by most ships capable of launching them.

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.

Re:I don't see them replacing crusie missles

[Chyeld]

If the limitation in firing these is generating the power to fire, it won't matter if you have 60 launchers or just 1, you still will only get ten shots off in a day. Unless you are including the cost of a whole need power plant for each launcher.

That said, the point of "How many cruise missles do we expect to actually fire in one day?" is a good one.

Re:I don't see them replacing crusie missles

[Kadin2048]

*grumbles something about failure to improve nuclear generators for destroyer use*

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:I don't see them replacing crusie missles

[TFloore]

I'm just pointing out that the military can solve many limitations by throwing money at them, and no one in the government is embracing plans to limit military spending at this time.

You need to read more about the DOD budget process inside the Pentagon and the White House. It isn't so much that they are proposing spending less, as there are a LOT of fights over exactly where to devote the spending, and which service gets how much, and how it is portioned out. How much goes to maintenance, how much to new equipment purchases, how much to soldiers, sailors, marines, and airmen. How much to R&D like this?

Very high cost equipment does indeed get canceled, simply because it costs too much. Usually measured as "too much over budget" but it is related to cost. Cost does matter.

The Navy has this as a very real problem over the next 10 years. The next generation aircraft carrier is projected to cost $10 billion. The Navy currently spends $10 billion per year building ships and submarines. A ship must be fully appropriated in the year that construction is begun. The year they start building the next-gen aircraft carrier, does the Navy simply not build any submarines, which they want to build 2 per year for a cost of $2.2 billion each? How about DDG-51 class destroyers, at a cost of $1.4 billion each? Or DD(X) (now renamed to DDG-1000) class destroyers, at a cost of about $3 billion each? Amphibious assault ships, like the LPD-17, which I don't know a cost for, probably north of $1 billion? Or LCS ships, for the low cost of about $400 million each?

What doesn't get built the year they start the next aircraft carrier?

The Air Force has the same problem, with F-22 aircraft that cost $200 million each... they aren't buying 600 of them like they planned 10 years ago. Instead they are getting... 190 I think. Ditto with the F-35 (JSF), which they are not buying 4,000 of, or whatever the original purchase number was, because they are also fairly pricey.

Just because the military works with large budgets, doesn't mean that the cost of equipment doesn't matter. It matters very much.

And they really do care about limiting costs, because it really does affect how many they can buy.

Where can I get one?

[Anonymous Coward]

I'm a member of the NRA, I didn't see this in the last catalog.

Power Sources

[nick_davison]

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.

If only we knew when lightning was due to strike some sort of a clock tower? Surely, then, we could harness the power needed.

If that doesn't work, perhaps some new technology involving trash?

sooo...

[Anonymous Coward]

by June they'll get the quad-damage powerup working?

More nuclear ships?

[TheWoozle]

So, do the electrical power requirements for this mean that the Navy will once again be building nuclear-powered ships?

physics of railguns

[smellsofbikes]

I have *never* understood how railguns work. Here is an explanation, although it still leaves me frowning and making funny shapes with my fingers all stretched out.

One presumes there are sonic booms associated with this. Anyone know if they're louder or quieter than the explosions associated with heavy ship artillery?

Re:physics of railguns

[sjaskow]

Well, a little googling turned up this which seems to explain it better without of the nasty physics technobabble. And this is how to do it yourself.

Well

[everphilski]

How many million-dollar cruise missiles are you firing a day?

Most likely it will end up as an augment. One of the virtues of this system being, though, it can set up a shot quicker than a Tomahawk.

Not sure about this

[thewils]

It will allow the US Navy to miss targets from much further away.

Slight correction?

[Civil_Disobedient]

The Navy isn't estimating a price tag at this point, with actual use still about 13 years away.

I think they mean deployment, unless the Navy knows something Congress doesn't. Which wouldn't surprise me.

Launch Loop

[cutecub]

You're talking about a Launch Loop.

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

Amount of power (energy really)

[Beryllium Sphere(tm)]

32 megajoules is less than 9 kilowatt hours.

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.

Admiral Gates

[Anonymous Coward]

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.

Nobody will ever need more than a 64 Megajoules rail gun.

power not the problem

[EricBoyd]

Running a few quick calculations shows that power is not likely the cause of the delay between firings. If you have 10kW to power your system, you can fire a 64MJ blast every 1.78 hours. If you have 100kW, time to fire is only 10.7 minutes. Obviously for the smaller railguns the power requirements are even less. I'm no expert on how much power is actually available on those big boats, but somehow I doubt that 100kW is out of reach.

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.

Forget Replacing Cruise Missiles...

[Wandering Wombat]

... these would almost replace Navies.

Come on, if you could fire a projectile 200 miles, you could just mount these on coastlines, serviced by ground-based power plants. True, it wouldn't replace navies ENTIRELY, but it would suddenly become extremely UN-economical to have one with even the slightest capability to get near a shoreline. Pushing back aircraft carriers 200 miles would severely reduce the flight time of the planes, which now have to fly a lot farther just to get to the coastline, let alone targets inside countries.

On the plus side, land-locked countries can now hunt whales for food. :)

Not electricity

[SamSim]

I'm almost positive the main issue is not electricity generation but rail friction. The best rail guns I'd heard of until today needed completely overhauling after each test firing because the rails themselves are damaged so badly as the projectile passes. Coil guns are better in this respect, as the projectile doesn't have to touch the coils...

Re:Not electricity

[JesseL]

The problem isn't friction, it's spark erosion.
The projectile in a rail gun should barely be touching the rails at all so it doesn't get welded in place. You end up with the equivalent of a huge arc welder traversing the rails with several thousand degree plasma.

Rail damage

[PIPBoy3000]

Excellent point. Here's a quick reference from the Wiki article:

Full-scale models have been built and fired, including a very successful 90 mm bore, 9 MJ (6.6 million foot-pounds) kinetic energy gun developed by DARPA, but they all suffer from extreme rail damage and need to be serviced after every shot. Rail and insulator ablation issues still need to be addressed before railguns can start to replace conventional weapons.

Power is relative, I guess.

[LordByronStyrofoam]

When I worked on General Atomic's Doublet-III experimental fusion rector, in the early 80s the energy for the machine was supplied by a three-story motor-generator constructed below-ground at the site. The motor ran off 440V mains and when powered spun itself, the generator and a 400-ton flywheel at 480rpm. It took twenty minutes to get the thing up to speed.

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.

Probably sufficient for a first stage.

[HighOrbit]

No, because when you shoot a projectile, you're putting it into a orbit that intersects the earth. You need some other impulse source to circularize the orbit.

Or, the rail gun could just be used as the first stage, second stage would be a solid chemical rocket which would take it the rest of the way and shape the orbit. The hard part then is getting the rocket engine, fuel, and nav-instruments to take the inital g-force of the rail-launch. The article mentions this:

"When this thing leaves, it's [under] hundreds of thousands of g 's, and the electronics of today won't survive that," he said. "We need to develop something that will survive that many g 's."

From the above, I'm assuming they have a reasearch project underway that would directly translate into launch survivability for the hardware. I'm not a electrical or mechanical engineer, but I'm going to guess that electronics embedded in high-impact composite ceramics (a la tank armor) might be the ticket here. The rocket engine and the fuel are another story. My understanding is that solid rockets are relatively simple construction (compared to liquid) so they would be the best candidate for survial. Pretty much every weld or joint I can think of would come apart under those kind of forces, so the fewer parts the better.

Re:Probably sufficient for a first stage.

[ceoyoyo]

The other problem is finding some sort of material that can survive the heating. If you're going to reach an orbit that doesn't take much fuel to circularize you're going to have to be going at more than orbital speed coming out of the barrel and fly at a fairly shallow angle to the surface -- through dense air. That's going to make the space shuttle's reentry look like child's play.

Re:Probably sufficient for a first stage.

[DerekLyons]

No, because when you shoot a projectile, you're putting it into a orbit that intersects the earth. You need some other impulse source to circularize the orbit.

Or, the rail gun could just be used as the first stage, second stage would be a solid chemical rocket which would take it the rest of the way and shape the orbit. The hard part then is getting the rocket engine, fuel, and nav-instruments to take the inital g-force of the rail-launch.

No - getting the hardware capable of surviving the G-forces is the easy part. The hard part is explaining to the beancounters why you are replacing a 50 million dollar first stage with a 10 billion (or most likely more) dollar accelerator - and not reducing your launch costs significantly because of vastly increased infrastructure maintenance and operations costs.
 
There's a reason why only the lunatic fringe of the alt.space community keeps insisting that an EM accelerator is the 'only way to go'.

Piece of cake.

[raehl]

Use the rail gun to launch a big, heavy projectile into orbit.

Attach projectile to giant bungee cord.

Attach giant bungee cord to object you want in orbit.

Give object giant scissors.

Expanding on this, you could tie one object with several rubber bands to several projectiles.