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

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.

More nuclear ships?

[TheWoozle]

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

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.

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.

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

[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.

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.

[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'.