Navy Sets World Record With Rail Gun

http://www.foxnews.com/scitech/2010/12/10/navy-railgun-shoots-bullets-electromagnet/

by gibsonf1 • 16 years ago

91 81 16 years ago

hugh3• 16 years ago

Pretty awesome.

There's an unfortunate focus in the admiral's comments on ship-to-ship warfare, which really isn't something we get a lot of nowadays.

What's deliberately not mentioned is how useful this might be for shooting down a missile at launch. It is, as they say, hard to hit a bullet with a bullet. But hitting a bullet with a much faster bullet...

iuhjyftgrd• 16 years ago

That's their main use

With a missile coming toward you at Mach 2-3 you don't want to be shooting subsonic cannon shells at it.

The rail gun ammunition is much smaller so you can carry much more of it and make a much more mobile gun turret because it doesn't need to store tonnes of shells or have a feed back to a magazine.

Estragon• 16 years ago

But if you look at the video, it's clear they're a long way from making any kind of agile turret out of this. It's HUGE.

tsotha8• 16 years ago

They'll be able to hit incoming missiles, but the primary strength of the system is as long-range artillery for land attack. It won't have the rate of fire you'd need to defend yourself against multiple incoming missiles.

steve19• 16 years ago

Thier main use will be hitting targets far in land.

The article says "Indeed, a railgun could be used to inflict just such harm on another vessel.", which is true, it could be used for this purpose, but they would not be sinking money into this just for that.

gvb• 16 years ago

"We're also eliminating explosives from the ship, which brings significant safety benefits and logistical benefits," Ellis said. In other words, there is less danger of an unintended explosion onboard, particularly should such a vessel come under attack.

The first half (logistics benefits) is a good statement. The rephrasing the the second half is bogus.

Joules are joules the world over. If the enemy fire hits the caps full of joules, it ain't gonna be good for the good guys even if there are no conventional explosives involved.

1053r• 16 years ago

Joules are joules, but what you are failing to account for is the form the joules might take. If the enemy hits the caps and they explode, an amount of energy equal to one projectile launch is liberated.

If, on the other hand, you take out a magazine, you liberate an amount of energy equal to all the shots the ship is capable of taking ALL AT ONCE.

The energy necessary to fire all those shots is probably still on board, but it is likely in the form of a nuclear pile in the reactor, which is shielded up the wazoo. Even if the ship is running a conventional generator, diesel fuel doesn't have a tendency to explode in quite the same way as gunpowder.

bigiain2• 16 years ago

That's true, but 33megajoules is almost exactly the amount of energy in 1L or 1/4Gal of gasoline. I don't know how much explosive a typical ship mounted canon requires for propellant and payload, but even given all the inefficiencies turning gasoline into electricity Id be quite surprised if there's quite a bit less energy on board to supply the rail gun.

InclinedPlane• 16 years ago

The mechanism of storage makes all the difference. If I store my Joules as, say, wood that has dramatically different failure mechanisms than if I store it as RDX. Even if the difference is just diesel vs. RDX. It's easier to prevent an explosion hitting diesel fuel from destroying a ship (it's been done since WWII) than it is to prevent an explosion hitting a stockpile of explosives from destroying a ship.

Even more so if the energy is coming from a fission reactor. Since the energy source is comparatively more compact and can be protected with armor more effectively.

zoomzoom• 16 years ago

What is the possibility of using these for space launches?

edit: obviously would have to be slower then these for the sake of any fragile cargo (including people)...

dasil003• 16 years ago

Hard to imagine anything useful withstanding that acceleration. You could make a longer launch tower, but how tall would it have to be?

cperciva2• 16 years ago

For humans who can survive an acceleration of about 3 g, you'd need a 1000 km long railgun in order to deliver enough energy.

For cargo a railgun a few miles long would probably be enough, but designing a missile which can survive surface air densities while travelling at orbital velocities would be very difficult.

SerpentJoe2• 16 years ago

Why not aim for the horizon? That way your track can be on the ground, and even better your impulse is spent approaching orbital speed rather than struggling against gravity drag. Even traditional space rockets turn east as quickly as possible, and a (semi) ballistic launch can do it from the start.

That said for human payloads you'd need a really long track, tens or hundreds of kilometers. I wouldn't want to live near the launch end. (edit: to get a useful amount of speed; still assuming rockets to get us the rest of the way)

kgermino2• 16 years ago

Well lets see:

Assuming:

Launch Speed: 17,180 mph (Speed of Space Station) [1]

Launch Acceleration: 25g (Based on my understanding of what humans can survive) EDIT [2]

Just using that as a rough estimate and Wolfram Alpha we get 242,250 meters, or about 150 miles.

http://www.wolframalpha.com/input/?i=17,239.2+mph+/25+gs

http://www.wolframalpha.com/input/?i=31.434+seconds+at+17,23...

Please feel free to check my math and yell at me.

[1] http://en.wikipedia.org/wiki/International_Space_Station

[2] cperciva [http://news.ycombinator.com/item?id=1993399] used 3g. Based on that you would have to multiply the launch distance by (25/3) and get 2,018,750 meters, about 1,250 miles. Again please correct me if I got something wrong.

tsotha8• 16 years ago

Rail guns wouldn't be very useful for delicate things, but you could, in theory, use one to launch bulk supplies like fuel and water. The problem is the projectile comes out of the gun so fast most of the weight is going to be taken up by shielding. If you have to put up with a sucky mass factor you may as well build a rocket instead.

A ram accelerator is probably more practical in any case.

edj• 16 years ago

There appears to be potential. A quick google search turned up 'Launch to Space With an Electromagnetic Railgun' in IEEE Transactions on Magnetics. [1]

"The extension of this technology [rail guns] to the muzzle velocities ( 7500 m/s) and energies ( 10 GJ) needed for the direct launch of payloads into orbit is very challenging, but may not be impossible."

[1] http://research.lifeboat.com/ieee.em.pdf

hartror• 16 years ago

Not much use on earth given the length of the rail required to launch at a reasonable g force but very practical on the moon where there is a lot more space and a lot less gravity (and no atmosphere to speak of).

pingswept2• 16 years ago

"[A] railgun offers 2 to 3 times the velocity of a conventional big gun, so that it can hit its target within 6 minutes."

I'd expect that most projectiles decay exponentially toward a terminal velocity, so the impact of shooting a bullet faster is negligible when it's going to be in flight for 6 minutes. Anyone know whether that's true for long range projectile weapons these days?

cperciva2• 16 years ago

Railgun ammunition is designed to lose as little kinetic energy as possible. After all, there's no point hitting someone with a non-explosive projectile unless it's moving fast.

pingswept2• 16 years ago

This suggests that the terminal velocity of a rail gun projectile is around Mach 5: http://www.globalsecurity.org/military/systems/ship/systems/...

I guess I can spend my time worrying about other things!

vl4• 16 years ago

Lets get bunch of rails into the low polar orbit. Once a 1000 or so is deployed, there will be an almost-instant (20 minutes) strike capability for any location on the earth. The good part is that kinetic energy of re-entering rail will be unmatched by any railgun.

On the serious note, they didn't specify the weight of the projectile, and this is quite important factor. Comparison of the energy delivered at the target range to the energy delivered by the conventional winged missile would be useful as well.

Blog of the guy who build portable supersonic railgun at home (in Russian): http://railgun.org.ua/ Check out his video page: http://railgun.org.ua/video/

bigiain2• 16 years ago

If you take the numbers from the article as accurate, 33 megejoules at Mach 7 means the weight is ~15kg (assuming I got all my conversions and orders of magnitude right, feel free to do your own e=1/2mv^2 calculation...)

aidenn0• 16 years ago

I got ~10kg from the 2500m/s number, and under 12kg from the Mach 7 number. Google agrees:

http://www.google.com/search?q=2*33megajoules/(2500+m/s)^2+i...

http://www.google.com/search?q=2*33megajoules/(7+*+speed+of+...

borism3• 16 years ago

Projectile speed will be much less after it has travelled 100km.

pak• 16 years ago

I don't think other world powers would be totally cool with us putting superweapons into low polar orbit right over their heads... you should totally expect those satellites to be shot down as soon as you put them up there.

vl4• 16 years ago

Why would they shoot down relatively harmless rails from the orbit and not other already existing spy satellites?

icegreentea2• 16 years ago

You already have 20-30 minute strike capability for any location in world. You've had it for decades.

What you want is 20 minute strike with less warning than existing ICBMs. And also banned. The nuclear weapons reduction and restriction of weaponization of space treaties are some of the successful treaties with regard to controlling weapons that anyone, let alone the United States has been involved with. Violating said treaty will bring ridicule and anger to whoever breaks it, and a non-miniscule chance of the other major nuclear powers launching all their nukes.

smhinsey3• 16 years ago

As much as I would prefer otherwise, it seems pretty clear that space has already been weaponized. Between the Shuttle the X-37, and whatever else exists, for all we know there are already satellites in orbit armed with kinetic kill vehicles.

vl4• 16 years ago

By "strike capability" here I mean "small payload pin-point strike capability", not "nuclear warhead". But you are correct in that it's possible to use ICBM to deliver rail to the target.

PaulHoule• 16 years ago

No, we need something cheaper.

ICBMs are too expensive to use to deliver conventional explosives or kinetic kill projectiles. Forget bioweapons and toxins, they're not any deadlier than cluster bombs.

The power of an explosion follows an inverse square law, so you can destroy something with 1/4 the explosive if you can get twice as close to it.

If you could drop thousands of 25 lb bomb equivalent devices an hour with GPS accuracy at a city, you could wreck it's infrastructure in a few weeks.

zitterbewegung2• 16 years ago

Yea except that inconvenient treaty that states you can't put weapons in space. Oh and also if you try to do this China would just try to shoot it down anyways. http://en.wikipedia.org/wiki/Outer_Space_Treaty

ahi• 16 years ago

A big rail gun is nothing new. The hard part, the part they still haven't figured out, is firing the thing without blowing it up at the same time.

essayist3• 16 years ago

This is great! When the Soviets come roaring through the Fulda Gap, or the Japanese descend on Pearl Harbor, we got 'em!

Oh, wait. We're preparing for the last war or even the one before that, all over again.

How does this help in the world of asymmetric warfare, failed states, nukes in container ships, and Stuxnet? (I'll bet the Maginot Line was pretty cool technology in its day as well.)

wazoox• 16 years ago

> I'll bet the Maginot Line was pretty cool technology in its day as well.

Definitely. Hidden tunnels with high speed trains to bring ammunition and personnel at any point in no time; hidden turrets in the forest that emerge from the ground; dragon teeth and minefields prevent tanks from going through.

Unfortunately big brass love big weapons, big bombers, big ships, big guns; never mind if they're useless nowadays in a world of guerilla and IEDs. The future is not the F22, it's a slow and cheap remote controlled drone with a propeller.

stcredzero10• 16 years ago

The future is not the F22, it's a slow and cheap remote controlled drone with a propeller.

It's a slow but highly efficient autonomous drone with GPS and a terrain map.

nickpinkston3• 16 years ago

Well, you may be surprised by the increasing relevance of naval forces in our modern world. Even though big ships fighting Bismarck style is rare, big ships are still very useful in securing seaways for shipping. This is why China, India, S. Korea are all building up their navy. Sure, SpecOps / "terrorists" grab the headlines, but remember that countries have many other threats and don't openly promote them without cause.

stcredzero10• 16 years ago

Yes, spending $569,000 on a cruise missile to take out a merchant vessel of comparable cost wouldn't be good economic warfare doctrine. If the navy can develop weapons that can sink merchant vessels from 200 miles away with dirt-cheap munitions (like a dozen $1000 ceramic slugs) then this makes for a more credible threat.

essayist3• 16 years ago

Point taken. Still, it leaves me wondering: what's the "rail gun" of diplomacy - e.g. how would serious money spent on R&D help us resolve the issue of Israel and the Palestinians?

And what's the "rail gun" for nation building - how would serious money spent on R&D help us create a stable, democratic Afghanistan?

I fear we're stuck in the "meta" version of "if all you have is a hammer": in terms of budget, all we have, in international relations, is the Defense Department. It has its uses, but its effectiveness is increasingly limited, not by dollars, but by our vision.

MichaelApproved• 16 years ago

So it leaves the gun traveling at Mach 7 and can go 100 miles but how fast is it going when it reaches the target 100 miles away? By the time it reaches the target most of it's energy is lost. The main power of this weapon is the kinetic energy it delivers to the target but that information is nowhere to be found in the article.

tsotha8• 16 years ago

>So it leaves the gun traveling at Mach 7 and can go 100 miles but how fast is it going when it reaches the target 100 miles away?

The one they plan to deploy is supposed to go something like mach 20 and have a ballistic trajectory. Not something you could destroy a city with, but it'll make a bigger bang than an 8-inch shell.

stcredzero10• 16 years ago

Navies still get an awful lot of leverage out of the ability to destroy merchant vessels.

CallMeV• 16 years ago

When they started putting big guns on battleships, they came up with a new term: "gunboat diplomacy." When the Easter Uprising began in Ireland, the Royal Navy just sat their gunships in the bay and started shelling them from a safe distance.

So I guess they're hoping that they can bring back gunboat diplomacy in a form more suited to the 21st century. And if they're aiming for ranges of two to three hundred miles, I guess that theoretically means that no part of the UK would be entirely safe except maybe Birmingham, and that's mostly because nobody wants to go there even to blow it up.

kahawe• 16 years ago

I am sorry, I have to say this... my Quake bits won't let me rest otherwise.

"Now they just have to figure out the Quad Damage and it's going to be insta-gibs on any target!"

Murkin• 16 years ago

Wonder if a startup could get those Tomahawks down to 60,000$ a pop.

lispm• 16 years ago

The last thing we need is new weapons.

dstorrs• 16 years ago

Ok, granted, this is cool. And I see a lot of utility for space launch and other applications, so I support the research.

My question: does it actually have practical utility as a weapon of war for the modern US Navy? This seems like fighting the last war -- this is about building a weapon that goes on giant ships, when the new war is all about information and special forces strikes.

essayist3• 16 years ago

Yup. See the "Maginot line" discussion above.

Navy Sets World Record With Rail Gun

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