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back to article US Navy preps railgun for tests

The US Navy’s Office of Naval Research is preparing to test a prototype railgun delivered by BAE Systems under a $US21 million contract signed in 2010. The industry prototype – a kind of dream machine for Mythbusters’ fans – is due for tests in coming weeks at a facility in Dahlgren, Virginia. The ONR’s aim is to develop a …

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Two words ...

... terminal guidance.

Or, place a special forces spotting crew with a laser guidance system.

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@Chemist

"it will just go through like a rifle bullet through paper"

When you're a hundred thousand tons of metalwork, holes all the way through from top to bottom tend to be unhelpful when you want to stay afloat.

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Of course

if you make it into a sieve it will sink but it seems rather far fetched to assume that it will be hit a sufficient number of times BELOW the waterline. If its a small vessel then game over and if the projectile hits something heavy or critical that it can vaporise/ be vaporised by then ditto.

100000 tons takes a lot of sinking with small holes.

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It's not for ship-to-ship combat.

It's for precision bombardment of hardened installations inland before you send your own fighters in, or for destroying incoming aircraft and missiles.

Good grief, don't you people watch Transformers... Then again, fair dos, it was the second one.

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Indeed, not ship to ship, but ship to ground.

As mentioned, it's a replacement/alternative to using cruise missiles, so will most likely be being fired against things like anti-air and radar emplacements, hardened structures, airfields, army bases, comms towers etc.

In essence, neuter your enemy from 50 to 200 miles away, before they can hit back, and before sending the rest of your forces in to mop up.

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@A Dawson

5600mph is 1.555555 miles per second.

100 miles, would be 64.285714 seconds if the round didn't slow down.

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Stop

before sending the rest of your forces in to mop up....... before christmas? or sooner?

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I'll take the option to hit fuel storage

or the modern equivalent of the gunpowder magazine.

And I expect a burst has a better shot of connecting with a critical structural support than you'd imagine, especially if it slices through the whole ship as you seem to be implying it would.

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sweet

another application of course that could come from this is a rail gun/coil gun assisted way into space.

of course it would have to be helluva lot longer for a more gentle accelleration but if you were to build a big one of these up the side of a mountain.....

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Boffin

Interstellar railgun

We could drill through 1 Ceres. That's a railgun near 1000 km long in near 0 g.

There's plenty of water and such to make into air and traditional rocket fuel. You can store up hydrox and use it for burst power too. Being in the asteroid belt it's probably a rich mine of iron ores on the surface as well.

Round figure the 1000 km railgun launcher. From 1 Ceres' orbit solar system escape velocity is 30 km/s or so and its orbital velocity is 17, so 13 more km/s is needed as long as you're headed the right way. It's a bit more than Earth escape velocity in near-0g. This is just a hair short of 10 g's over the length of 1000 km, in 154 seconds. That's well into human survivable territory which is well over 17 g. Augment the launch boost with some solar sail fluffed by both the sun and/or some high-intensity lasers and we're well away even without complex stuff like gravity slingshots or onboard thrusters. For an unmanned probe you can do well over 100x that acceleration.

And the rest of the time you can be a logistics hub for the human mining settlements on the asteroid belt.

It's limited to stuff on the solar system plane though for the 10+g launch, give or take a few degrees. To go close to north or south requires some freaky calculations, or using Jupiter or Saturn to both both boost your velocity and change your direction - and you're going to need some onboard traditional rockets to pull that off. A shame Alpha Centauri is almost due north. The space geeks can figure that out.

We can head for the stars now with available technologies if we want it badly enough and can find some patient volunteers. Or we can send much faster unmanned probes. Or both. It would be interesting if Dawn mission got to Ceres and found it full of odd tunnels.

http://en.wikipedia.org/wiki/G-force

http://www.wolframalpha.com/input/?i=solve+acceleration+to+13000+m%2Fs+in+1000+km

http://www.ajdesigner.com/constantacceleration/cavelocityt.php (13000, 0, 85)

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@ Mikel

Interesting post. However, a couple of things I should point out:

1) Alpha Centauri is due south, not north. It's one of the pointers to the Southern Cross, and as such it's within 30 degrees of the south celestial pole. (It's circumpolar from where I live in Adelaide, Australia)

2) Mounting a bloody great fuck-off railgun launcher through the guts of Ceres and launching multi-hundred-ton spacecraft from it at multiples of earth gravities will, by virtue of Newton's 3rd Law, undoubtedly do wonderful and interesting things to the orbit of said asteroid. If you orient the launch vectors appropriately, you could even start it on a collision course with Earth, which, considering Ceres is comparable in size to Texas, would go a long way towards doing the Universe the favour of removing the human race from it! ;)

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Ah, South.

Of course on Tuesdays you would fire the thing the opposite way - once the asteroid were more conveniently located. What am I, crazy?

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WTF?

Guess they still seize too much money from the populace.

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Linux

If my vote counted...

I'm pretty surprised this hasn't been touted as a "green gun" or a "zero emission sabot slinger." I'm more curious about which senator invested in which stock(s) prior to the funding of this lead-sled than if it will actually work, which I doubt. Not that it won't ever fire really fast, over-sized pellets, but I seriously doubt it will ever be effectively weaponized. Then again, if man was intended to fly, God would have given him wings. Penguin, because God gave them wings, and they still can't fly.

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Yay!

I like it! If you change "Sabot" to "Unpleasantness" it spells "ZEUS".

For have not the sages said: "Find ye a neat acronym and verily thou shalt be buried in funding dollars"?

You'd have to change the meaning to "unexplosive submunition" of some such for the press, of course.

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Trollface

Hang on...

You mean that BAE is actually producing something of value, and the American Navy is interested?

Oh right, the article was not written by Lewis.

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Fools and money are easily parted. Bravo BAE Systems.

Hang on ... You mean that BAE is actually producing something of value, and the American Navy is interested?

Oh right, the article was not written by Lewis....... ratfox Posted Thursday 9th February 2012 05:05 GMT

Err.... hang on a cotton-pickin' moment there, ratfox. BAE Systems has blagged $21million to try and produce something of interest to the US Navy’s Office of Naval Research and prepared to test for the destroying of things of value. And that is something altogether completely different.

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Useless Technology

As others have written, the trajectory can be observed and a counter-missile be launched for each projectile.

Also, launching something at excessive G-rates necessitate the projectile to be a stupid lump of material, as valves and other complex stuff won't survive the violent launch. So, no way for evasive maneuvers.

Missiles are still superior to this "exciting" technology, as they can accelerate at "moderate" G-rates of about 1000 m/s^2, and still reach several machs in very short time. They can include any complex tecchnology such as computers, radars, valves and steering surfaces.

These dumb projectiles can be downed using ESSM, now a standard weapon for all modern navies. (that definition does not include the British navy, though)

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I'm not sure that's true, as there's not going to be any explosive charges in the projectile, and it's probably got enough kinetic force behind it to plow through any explosion. Additionally as it's a solid slug of metal it's going to have a much smaller profile than standard missiles.

Also unless I'm completely uninformed, there isn't currently a defence against solid slugs except not being there. Another point would be that the ship that has this gun will be able to have a lot more ammunition than the opposing ship will have missiles due to the fact that it's smaller...

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So just explain to me how a Sea Sparrow missile can "down" a lump of hypersonic lump of tungsten (or whatever they are slinging out)? Short of vapourising it or knocking it off course, it will just keep going, energy intact.

One of the main drivers for this technology is logistics. Instead of having a magazine full off stuff that blows up, you just have an inert pile of projectiles, and a source of electricity. For a nuclear powered ship, that is already availabile in abundance. There lots of logistical issues associated with propellant, that aren't there for diesel.

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A few counterpoints.

First, even in sea-to-sea combat, such a projectile would be fired from over the horizon, meaning barring an aerial radar, the projectile isn't going to be detectable until it's already partway to you, cutting the reaction time. Second, most military naval vessels (especially large ones) can't turn quickly and take time to accelerate and decelerate, making it more difficult to perform evasive maneuvers. Basically, for evasive maneuvers to be effective most of the time, you have to already be performing them when word of the incoming projectile reaches you. Otherwise, the attacker is likely to simply fire a leading spread to account for the limited types of actions

As for intercepting the thing, no way. You're talking about a sizable lump of solid tungsten. FTR, tungsten is about as dense a solid metal as you can get without going into that bug-a-boo: depleted uranium. So you're talking a lot of mass traveling at high velocity (remember what the article said: mach 7.5). That means a tremendous amount of momentum, which physics dictates is going to be a bear to deflect. And since it's a solid slug, it's going to be a pretty difficult thing to hit. Explosive forces won't impart enough force to deflect it well, and even an ESSM isn't dense enough to work on direct contact: if this thing can penetrate a ship, what's to stop the projectile simply punching THROUGH the missile? And a Phalanx, while capable of spewying out a lot of lead, lacks the range to intercept it early enough for the deflection to have any meaning. So you're pretty much down to intercepting it with another massive kinetic projectile. Ask yourself: when was the last time you recall anyone managing to shoot one bullet with one other bullet?

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@Charles 9

"Ask yourself: when was the last time you recall anyone managing to shoot one bullet with one other bullet?"

Gunmen of the Apocalypse, Danny John-Jules, October 1993

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@"ESSM can't intercept electro-slug"

I agree that one would have to actually test an ESSM interception of one of the mentioned e-slugs. According to wikipedia (http://de.wikipedia.org/wiki/RIM-162_Evolved_Sea_Sparrow_Missile), ESSM missiles weigh 270 kgs, so when they impact the much less heavy e-slug, this should end in a ball of metallic vapour and maybe some minor high-speed fragments.

Regarding the "you can't hit a bullet with a bullet", modern electronics and thrust vectoring have proven otherwise. SM-3 shot down a satellite (which moves faster than most bullets) and the russians claim their systems can do the same or more.

Also, modern russian sea-skimming ASMs fly at speeds of mach 2 or more for several decades now. Intercepting these missiles is more difficult than intercepting a bullet, because they can now maneuver at high g rates. ESSM has been specifically designed to do that and the operating principle is much better suited to achieve its goals than dumb systems like gatling guns.

ESSM won't have the slightest problem to intercept the e-slug, as the trajectory is very predictable. Modern anti-ship missles are a much more dangerous threat than the e-slug. All I can think of is that the software has not been tested against the high speed of e-slugs, but that will eventually be done.

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it's only more predictable if you know where it was launched from. You then have to consider that the 10KG projectile has a volume (if it's tungsten) of 519.5cc, that's less than 1 litre (or will fit in a 10*10*10cm cube. Traveling at 5709MPH, and 24 miles from visual range, that's 15.13 seconds reaction time.

The ESSM will be traveling at around 3044MPH and to cover the same distance that would be 28.38 (assuming it was already at max speed). Simple maths says that they will meet each other after 9.8 seconds, at which point the ESSM will have travelled 8.35 miles. More research says that the response time for ESSM is around 6 seconds, which leaves the projectile at around 2.8 miles from it's target at point of contact. And this is assuming that they've picked it up at the maximum 24 mile range for the horizon on earth. If it takes them more than 3 seconds to detect a projectile that is smaller than your average sea gull, and due to aero dynamics will have substantially less radar profile than the gull, the ESSM won't have time to be launched before the ship has been hit.

Just as aside, the time it would take a missile traveling at mach 2.5 to travel the same distance would be around 45 seconds, so that 6 second response time wouldn't matter that much.

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Differences in technique.

It's not getting to the target that's the problem. It's what to do WHEN YOU GET THERE that's the problem. Missiles and slugs work very differently.

Intercepting a missile is possible because its primary action is chemical. It works with an explosive warhead. Defeat that and it'll just be a hunk of metal that isn't even designed to work on inertia. All you're trying to do in a missile interception is cause it to stop or detonate early.

A slug, on the other hand, is pure kinetics: inertia. If a ton of solid tungsten traveling at Mach 7.5 were to kiss an ESSM head-on, the inertia of the slug would more than likely cause it to penetrate the not-as-dense shell of the missile. It'd be like trying to deflect a cannonball with a bullet: it's not going to do much. IOW, a massive ballistic projectile is inherently missle-resistant due to its sheer mass. That's why tanks on the ground love sabot rounds and kinetic penetrators and why insurgents have taken lessons on bodging explosively-formed penetrators: because it's just very hard to beat PHYSICS.

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@Charles 9

They sound impressive your numbers but let's look at them at little more closely.

A 1 tonne Mach 7.5 projectile had a kinetic energy of ~3e9 J - that's 3000 MJ - that's rather out of the range of current discussion esp. if the launch efficiency is as low as the data in the article suggests.

It is hard to beat Physics

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Stop

@"I still think the e-slug is great"

Regarding the "high speed tungsten will cut through missile" argument, I don't think that the same physics as with "low speed" bullets apply. At speeds of mach 5, even a piece of styrofoam hitting a human will be deadly. So my guess is that the mass of the ESSM missile hitting the tungsten (or whatever they use) e-slug will vaporise both the slug and the missile.

Now to the "can't detect e-slug" argument: It does not really matter if you see the slug being launched or not; what matters is that you will see it several seconds before it will come close to you. Even a small part of the trajectory will be sufficient for software to calculate the rest of the trajectory. Also, the ESSM missile will track the slug and correct for any errors of the calculation. I assume it is sufficient to have 10 seconds of warning time to launch an ESSM. That would be 15km or more distance. Your Radar and IR sensors must be capable of doing that.

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Sectional density and Ballistic coefficients come in to play. The sectional density of the projectile will be extremely high. There probably isn't enough density in the missile to vaporize the projectile. A missile has a very low sectional density and is not designed to hit the target head on. That is very difficult to do.

The missile works by getting close enough to detonate and send a clod of shrapnel into the target. When dealing with other missiles or aircraft, this is more then enough to cause them to stop working. With a projectile like this, the best you'll do is alter its course.

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That's what I was noting.

Sure, an object at a speed of Mach 5 is dangerous, but how dangerous is it against ANOTHER object ALSO going at Mach 5...only much denser? It's like a Mini Cooper vs. a lorry, both at the same speed. It's gonna be messy for the missile.

As for the warhead, the projectile will not have a lot of cross section for an explosive force to apply, and it'll have all of the projectile's inertia to fight (and given its mass, there will be a LOT of it).

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While I was browsing the net looking for more info I came across this quote

"Ellis told FoxNews.com that the big guns on the deck of a warship are measured by their muzzle energy in megajoules. A single megajoule is roughly equivalent to a 1-ton car traveling at 100 mph. Multiple that by 33 and you get a picture of what would happen when such a weapon hits a target." here - http://www.foxnews.com/scitech/2010/12/10/navy-railgun-shoots-bullets-electromagnet/

Could this be what's meant by the following?

(equivalent, the ONR says, to a one-imperial-ton vehicle travelling at 100 mph, or a London bus going bloody fast).

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So how long before

We have hand portable rail guns, like in that Arnie movie (Eraser?)?

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Never. Energy storage density is the problem, just like in a phone.

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No so fast young man.. there isn't much energy in a bullet.

a .22 long round is according to wiki, about 67 lb ft. That's about 0.025 watt hours.

A lithium pack that fits neatly in a cell phone is maybe 3-20 watt hours.

I rest my case.

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Re : there isn't much energy in a bullet

~90 J from your figures - really small, far too small

~2 kJ from http://en.wikipedia.org/wiki/Muzzle_energy for a rifle bullet

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Mushroom

Soo.. ~0.6 Watt hours per shot? On a 1500mAh, 5.5v battery (standard smartphone Batt.) you would get about 12 shots. That sounds pretty practical to me.

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Need to allow for the low efficiency

The figures quoted in the article suggest the amount of energy imparted to the projectile is a small proportion of the energy used so the number of shots drops even further maybe by 20 fold

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Re: Re : there isn't much energy in a bullet

My laptop battery has an energy density of just over one half a megajoule per kilogram and it's not exactly military spec. So maybe 250 shots per kg assuming no losses. (Yes, there will be losses but on the other side battery tech is still improving rapidly) I don't exactly think a 1kg power pack would be a problem for Arnie. On the other hand I do have this image of a young Stallone with dozens of little phone batteries tucked into his bandolera.

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Something like this along with recently announced steerable ammo could make for a resurgence in big gun ships.

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WTF?

What this - no new unit of measure?

Come on chaps, a few LBGBF's* coming at you is not something to miss, well actually it is, since it would hurt!

As in: it wasn't that she was fat, but once she got dancing she was a few LBGBF's and anyone who got in her way...well.

*London bus going bloody fast

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Surely sheepsecs will do?

Or perhaps the a multiple of the speed of a laden swallow in a vacuum?

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Mushroom

bah

your mighty rail gun is no use under water...

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J P

Not to worry, we're working on an x-ray laser for the sharks.

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Nice thing about a massive projectile.

Once you actually get it into the air, it's going to have a LOT of inertia. IOW, it's going to take a lot of physics to make it alter its course. Plus, if it's shaped like your average kinetic penetrator (long and pencil-shaped), then there won't be a whole lot of drag on it, either.

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Pint

So we reinvented the cannon

Given that you can only realy fire metal and nothing fancy as anything with electronics would be at the mercy of alot of induced EM via the launch I can see why the Birtish don't have one - probably waiting to build there's from CERN parts once its decomisioned.

I also wonder what kind of high voltage capacitors they will use and how many as for all the will in the world I'm kinda against overloading nuclear reactors with a sudden heavy drain of power - dont want that steam turbine burning out I guess.

Also wondering how much kick this will have, can you face it behind you can up your top speed with pulsed firing.

Either way I look forward to the nighttime test fireings from it, should make from some pretty puictures :).

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Bah!

It's not the gun rebuild that takes time after a shot at The Atlantic Wall and the Pesky Hun hiding behind it, but digging out the ship and refloating it after the recoil sends it fifty feet up Beachy Head.

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