The US Navy's Railgun Program

Is this news? by Anonymous Coward · 2012-10-01 08:21 · Score: 4, Informative

Why is the summary written like we haven't heard about this before.

http://tech.slashdot.org/story/10/12/11/046205/navy-tests-mach-8-electromagnetic-railgun
http://tech.slashdot.org/story/12/02/08/152224/us-navy-receives-first-industry-built-railgun-prototype

Re:Is this news? by hairyfeet · 2012-10-01 10:36 · Score: 3, Interesting

The problem this is gonna have, is the same problem all sci-fi weapons have, and that is power.
To feed these things at a decent enough size to take the place of our old battleships in the shore bombardment role you are gonna need nuclear powered ships to feed it and nuclear powered ships are naturally rather large. The question, which is gonna become even bigger as time goes on, is whether building large ships will be logical in the wake of anti-ship missiles becoming cheap and powerful. Just as the carrier made the battleship obsolete so too may we see a day when the large carriers, cruisers, and destroyers become obsolete because your enemy can just launch anti-ship missiles at you until your ship sinks.
With our large bombers we can launch those from halfway around the world and hit a target but with a nuclear powered boat other than a sub you have a pretty large target that can't really move or dodge very well against missiles that can go insanely fast, be launched from just about anywhere, and are becoming cheaper by the day.
So while this is cool tech I have to wonder if like the age of the battleship its a tech whose time will be passed before the first ship sets sail. Unless we can find a way to make anti-ship missiles a non threat, which may be possible, after all we have seen those "electric guns" put out insane sheets of explosive rounds that could conceivably just grind the missiles up before they hit the ship, then frankly this tech won't be useful except in attacking your tech poor "jihadist with an AK" type. And if that is the ones you are gonna target why not just use what we have now? Its not like they can do anything against an F-18 at 35k feet with a smart bomb as it is.

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ACs don't waste your time replying, your posts are never seen by me.
Re:Is this news? by rahvin112 · 2012-10-01 11:19 · Score: 5, Interesting

Anti-Ship missiles are a bunch of hooey. Yes they are fast and damn hard to shoot down, but if you are are within range of one those with your navy you are doing it wrong. Oh yes, there are people in the USN that think we could engage in Littoral combat, but they are in the extreme minority.
No naval officer ever wants to bring his ship so close to shore that one of those missiles could hit it. And if you are out of range of ground fire the only way to fire is ship based, that exposes the firing ship to submarines which are damn near impossible to detect. The other option is submarine launch, which again on launch exposes the asset and anti-submarine warfare is very well understood at this point. And why launch an anti-ship missile from a submarine when a torpedo can be far more damaging.
The navy is working on a platform for the rail guns that uses current working technology. The systems they are developing will run on top of standard carrier nuclear generation systems. Just like the carriers you have two small nuclear reactors, put them in a large cruiser class ship. There aren't big guns like the old battleships so the ships become multi-role, able to host not only rail gun rounds but missile and radar emplacements. The best part about the rail guns is you do away with explosive munitions, your ammo and firing system are a bunch of wiring, capacitors and a hunk of tungsten for a projectile and you can spread the systems around the ship in a damage control technique (unlike current powder based systems that are a single weak point).
I actually believe the Navy's future plans are more sustainable and build-able than even the air-force's F-35 program. And their time line is even more believable with the first ship construction around 2016.
Re:Is this news? by rahvin112 · 2012-10-01 12:51 · Score: 5, Interesting

I shouldn't need to point this out as it's a critical aspect of US naval policy since WWII. The point of a US navy carrier grouping is to sit well outside ground fire range and use AIR power. This means planes with ranges that far exceed a missile, and cruise missiles that are nothing more than preprogrammed Kamikaze drones.
Maybe at some point the SunFire's and other supersonic Anti-Ship missiles will have a range equivalent to air power but the further they have to go the easier they are to shoot down.
The first rail guns will be small systems with short ranges of 200 some odd miles, but the future intent is to bring these up to 2 Ton 10,000 mile systems. They will have the ability to throw a hunk of tungsten so fast and so far that it's explosive force will be in the 30K ton of TNT range and it will be capable of penetrating almost a hundred feet of solid rock or reinforced concrete. They will be capable of putting a rod on target within 5 minutes of order. Railguns will revolutionize warfare, probably in a very bad way.
Re:Is this news? by s_p_oneil · 2012-10-01 14:41 · Score: 2

"Any country hostile to the USA would need to devote some of its resources, both money and brains, into similar RAD."
Not really, the Chinese will wait for us to sink the money into the tech, then steal the plans.
Re:Is this news? by camperdave · 2012-10-01 16:37 · Score: 3, Interesting

I shouldn't need to point this out, as it's basic logistics. Any plane, any weapon system that you can put on a ship can be put on land. Thus any land base can have just as much of an effective range that any (stationary) fleet can have. It doesn't matter that a naval railgun can put a 30 kiloton chunk of tungston on target within 5 minutes, because the land based system can do the same thing just as fast. Furthermore, land based weapons are not constrained as far as weight or size compared to what shipborne weapons are. They can be bigger and have greater range than the naval weapon.

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When our name is on the back of your car, we're behind you all the way!
Re:Is this news? by physicsphairy · 2012-10-01 17:50 · Score: 2

That assumes that your opponent has the same technology as you do. Otherwise, it is fully possible to have longer range weapons on your ship than they do in their land based facilities (and America generally does).
There's also some asymmetry in the importance of accuracy. It's a considerable difference if your projectile can fire 10 miles and is accurate to 1 square meter vs. can fire 11 miles and is accurate to 100 square meters. The latter might be fine for naval ships attacking a base but you might need the former if you are a base trying to fend off the naval ships (assuming you can get an accurate targeting of them in the first place).
And, in general, it may be a bad idea to sacrifice mobility even if that nets you bigger range. We're discussing projectiles which are going to penetrate all but the most protected bunkers. A big weapon installation cannot be defended. The only conceivable defense is for the target to not be in the spot that the enemy is shooting at.

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When things get complex, multiply by the complex conjugate.
Re:Is this news? by TheTurtlesMoves · 2012-10-01 20:18 · Score: 2

Running the numbers is not that hard. Lets say orbital velocity of 7.5km/s and a mass of 2000kg. E_k=mv^2/2 and that gives us 56GJ. Its 15MWh. Its a bit, but not totally insane. Now if we have a 15m rail gun to accelerate that with, assuming constant acceleration. From 2as=v^2 we get a=1.875x10^6 m/s^2 and from s=at^2/2 t=4ms. So that is a power of 14TW. Its a bit. But we have things that do this. For example the Z machine is more than 200TW IIRC. But then its only "on" for 100s of nanoseconds.

Consider that this would be run from a complusator. A 100T rotor spinning at 1000ms can hold a max of 50GJ. So yea, 56GJ is really a lot. However my reading on rail guns is that they would use lighter faster projectiles with less total energy. For comparison 56GJ is equivalent to about 13 Tons of TNT.

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The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
Re:Is this news? by TheTurtlesMoves · 2012-10-01 20:55 · Score: 2

For something moving at 11200m/s with a mass of 1815kg, gives a KE of 113GJ, or more than 3 orders of magnitude more than what you have.

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The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
Re:Is this news? by X0563511 · 2012-10-02 02:25 · Score: 2

The best part about the rail guns is you do away with explosive munitions, your ammo and firing system are a bunch of wiring, capacitors and a hunk of tungsten for a projectile and you can spread the systems around the ship in a damage control technique (unlike current powder based systems that are a single weak point).
Consider the amount of energy that would be stored in those capacitors. If that energy was released in an uncontrolled fashion, it would be just as bad as an ammunition store going off.

--
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
Re:Is this news? by hairyfeet · 2012-10-02 04:24 · Score: 3, Insightful

Not to mention the latest reports at places like defense tech have the new Chinese missiles being designed as "skimmers" which is literally a few feet off the top of the water when it gets within visual range of its target. All our missile defense is designed for the classic arc of a Scud style missile using a terminal trajectory hit the target NOT a skimmer. With the height of your average carrier they would be hard pressed to even point the weapons low enough to fire over the head of a Mach 2 skimmer, much less point low enough to hit it.
So I don't see how the "big blue blanket" we've used since WWII, with large groups of cruisers and destroyers surrounding the carrier, is supposed to work if the enemy can just fire off 40 to 50 skimmers and call it a day. At the cost of the cruisers and destroyers per unit even if they don't hit the carriers you're dealing with horrific loss of life and billions sent to the bottom, and if they launch 30 or more at a time I doubt a big blue blanket would have a prayer of stopping the carriers from getting hit as they are just too large a target and too slow to turn.
I have a feeling the cruise skimmer is gonna do to large carrier groups what air power did to the battleship, make it an obsolete sitting duck. All I can think of is the IJN sending Yamato to fight the USN without air cover and how the planes were able to just slam into it in waves, bomb after bomb and torpedo after torpedo until it went to the bottom. With the cruise skimmer it won't cost the enemy a single soldier or sailor and they can just send waves from different directions and overwhelm the task force, doing to the USN what the USN did to Yamato.
Ironically I see the USA making the same mistakes the Axis did in WWII, like Germany we are building insanely expensive and hard to build and maintain aircraft while the enemy builds cheap, reliable, and easy to maintain aircraft. As we saw in WWII having a few quality planes really doesn't help when your enemy can put 8 to 1 odds against and unlike WWII the F-22 and F-35 really aren't that much better than the MiG 29 and SU 35, not 8 to 1 better, and like the IJN we are relying on old tactics like the big blue blanket that with modern tech is REALLY outdated. We've basically gotten a free pass so far as we've only gone against technologically inferior enemies, but if we face a modern high tech military we would probably be in serious trouble.

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ACs don't waste your time replying, your posts are never seen by me.
Re:Is this news? by painandgreed · 2012-10-02 05:07 · Score: 2

"Any country hostile to the USA would need to devote some of its resources, both money and brains, into similar RAD."
Not really, the Chinese will wait for us to sink the money into the tech, then steal the plans.
Except that was essentially what the USSR was doing with the USA's electronic and computer designs. Trouble was that without the necessary R&D, they really didn't even understand what they were copying. That allowed us to slip them designs that didn't work and resulted in things like the Soviet Urengoy–Surgut–Chelyabinsk natural gas pipeline.

Old news... by Valor958 · 2012-10-01 08:22 · Score: 5, Informative

In and of itself.. this article is very lacking and at face value is old news. We have been developing railguns for a long time. We have the principles down, but the problem comes with the energy needed to really run a weapons effective version.
Even the linked article just referrences an overview of the technology and it's goals. Why not an update... did they make a breakthrough? SOMETHING...

Re:Old news... by binarylarry · 2012-10-01 08:26 · Score: 2

What they need is some kind of ship with a nuclear reactor that can generate enormous amounts of power.
Now I wonder who has technology like that in the pipe?

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Mod me down, my New Earth Global Warmingist friends!
Re:Old news... by ericloewe · 2012-10-01 08:40 · Score: 2

Extra reactors are much safer than carrying around tons of high-explosives, and you get some extra room to carry the inert ordnance.
Re:Old news... by EvolutionInAction · 2012-10-01 08:41 · Score: 5, Informative

Unfortunately you're dead wrong. We can power them. Maybe not easily, but we can do it. The problem is that you get something like three shots before the rails have eroded to the point of uselessness. Too much friction, too much electrical arcing.
Re:Old news... by K.+S.+Kyosuke · 2012-10-01 08:43 · Score: 2

What they need is some kind of ship with a nuclear reactor that can generate enormous amounts of power.
Actually, what they most likely need is some sort of fast-startup generator for the short peak power periods required by such a weapon, e.g., something like an MHD generator.

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Ezekiel 23:20
Re:Old news... by sjames · 2012-10-01 08:45 · Score: 2

I'll bet the rails are cheaper to replace than 3 tomahawk missiles.
Re:Old news... by jafiwam · 2012-10-01 08:57 · Score: 2

What they need is some kind of ship with a nuclear reactor that can generate enormous amounts of power.
Actually, what they most likely need is some sort of fast-startup generator for the short peak power periods required by such a weapon, e.g., something like an MHD generator.
If they haven't changed plans drastically, the peak power is handled by huge capacitors. So it's a reliable and large capacitor problem, plus a "we need more overall electrical output than we used to" problem. A nuclear power run ship makes a lot of sense if you are going to be using lots of power. For multi-shots, they may have to just add more capacitors and count on some lag time between bursts.
Re:Old news... by Nadaka · 2012-10-01 09:03 · Score: 4, Interesting

Next gen aircraft carries are already putting in an extra reactor in order to run electromagnetic launch catapults instead of the high maintenance hydraulic ones we have now.
When that power isn't being used for launching aircraft, it can be used for launching railgun projectiles.
Re:Old news... by FileNotFound · 2012-10-01 09:13 · Score: 4, Insightful

Yeah - but can you replace the rails while underway?
Here's something for you - a DDG carries 56 Tomahawks, but can load up to 96 if they carry nothing but Tomahawks in their VLS. Rate of fire - 1 missile per second.
The real question is, what are you going to shoot at that's only 200mi aways? 200mi might sound "far" but reality is that modern anti ship missiles have range 500-1000 miles.
No DDG is going to sail up to 200mi of a hostile to shoot it with a railgun when then can launch a Tomahawk with it's 800mi range for a Block III or 1500 for Block IIs.

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In Soviet Russia, the television watches YOU!
Re:Old news... by John+Hasler · 2012-10-01 09:32 · Score: 2

> The real question is, what are you going to shoot at that's
> only 200mi aways?
Incoming antiship missiles.

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Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Re:Old news... by Anonymous Coward · 2012-10-01 09:48 · Score: 2, Interesting

The US Navy has been evaluating designs of all-electric powered warships for thirty years or more. The main difference with current warships (like the Arleigh Burke) would be electric motor main propulsion instead of reduction gear off gas turbines. Nothing they (or Congress) are quite comfortable with yet. Destroyers and cruisers would be based on gas turbine generators which have been getting 40+% total thermodynamic efficiencies in operation for some time (vs 25-35% for the old steam boiler warships). IIRC, the Navy proposed an all-electric warship for construction within the last year or two, but it was shelved (as in "maybe next year, let's stick with Arleigh Burkes for now"). Gas-turbine driven generators combined with capacitors would provide enough electricity for railguns in those designs.
Just as an aside, if you want to design starships for games or stories, I recommend you examine US Navy warship design. There are documents "out there" (however boring) on the design requirements and design process. Observing how Navy designers have dealt with often directly conflicting requirements, and indirectly conflicting requirements can be directly applied to starship design, non-combat as well as combat; they are both many, many dimensional optimization problems.
Re:Old news... by idontgno · 2012-10-01 09:50 · Score: 2

The only sticking point is that an aircraft carrier is not a gun cruiser. Or even a destroyer.
Frankly, a CVN is not supposed to get within gun range of anything that can shoot back. That's what its warplanes are for.
Things may be a little different if "gun range" is more than 100 miles, but again... a carrier full of warplanes and unmanned combat air vehicles doesn't need a popgun, even if it's a railgun.
Maybe smaller railguns for point defense... assuming they can be rapid-fire and have better range than current 20-30mm gatling guns. And you're willing to accept friendly fire on your destroyer screen from all the strays.
If this railgun will be the primary weapon of any type of ship, it would be a destroyer or littoral combat ship (LCS), assuming you can build electrical generation capabilities for it that fit into ships of that smallish size.
The number one reason for guns on ships (instead of missiles, drones, or warplanes) is cheap shore bombardment. Considering full-up system costs, armed drones may be cheaper.
I don't wanna pooh-pooh cool tech that blows stuff up, but this seems like a solution looking for a problem to solve. Unless we're gonna go back to big-gun cruisers mostly for naval gunfire support, I don't see the point. (Although I'm sure the Marines would appreciate it.)
I can only envision one situation where the current naval airpower solution wouldn't work: opposed amphibious operations against an opponent with a strong air defense network. And then, the first thing you do is blind it using stealth assets and saturation cruise missile strikes, a la Gulf War I. Problem solved.

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Welcome to the Panopticon. Used to be a prison, now it's your home.
Re:Old news... by EvolutionInAction · 2012-10-01 09:53 · Score: 2

Railguns are exactly the wrong answer for point defence. You want lots of material in the air for that. Railguns put one very, very fast projectile out.
Re:Old news... by Hognoxious · 2012-10-01 09:55 · Score: 3, Funny

Frankly, a CVN is not supposed to get within gun range of anything that can shoot back. That's what its warplanes are for.

Put a socket on the side and run a fucking massive(tm) extension cable to the gunboat or whatever the nouveau battlecruiser is called.
Bunch of thickies round here.

--
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Re:Old news... by Phanatic1a · 2012-10-01 09:56 · Score: 5, Interesting

"They won't be willing to wait and it's not exactly a simple thing to change the power output of a Rankine cycle nuclear power plant at a whim."
Actually, it is, it's called a throttle. When you're in a nuclear submarine puttering along at 5 knots and someone drops a torpedo on you, and you want to get up to 30+ knots as fast as you can, you do it. You take more heat out of the coolant, which cools down the water in the reactor, which increases the reaction rate, which produces more power, this relationship is very tight and the changes can happen very rapidly. Way more rapidly than shoveling in more coal.
The power source is a non-issue. Gas turbine, nuclear, whatever, there's plenty of available power. A single destroyer carries 4 gas turbine engines that are each capable of 40,000+ shaft horsepower. It's generation capacity that's more of an issue, but even that just means "wait for a longer period of time between shots."
The means of delivering electrical power to the projectile without arcing destroying the rails is an issue. Ideally you want all the current in the world at as low a voltage as you can manage it, so capacitors aren't as good as a magnetohomopolar generator. But getting the power to put into the capacitors of MHG is not a complex problem.
Re:Old news... by Baloroth · 2012-10-01 10:03 · Score: 4, Interesting

No DDG is going to sail up to 200mi of a hostile to shoot it with a railgun when then can launch a Tomahawk with it's 800mi range for a Block III or 1500 for Block IIs.
...at ~$600,000 dollars a shot. That is... expensive, even for the US military, especially when fighting targets that aren't ~1,000 miles away, but which you still don't want to fly a plane over. Also, carrying 56 Tomahawks means you have a shit-ton of explosives on board just waiting to be detonated by a missile or bomb hitting the ship. The thing about railguns is they can be potentially combined with the new laser system the Navy is also developing for defense, meaning you have a platform that can't be hit by enemy missiles and can fire large-scale bombardments for nearly negligible cost (compared to the current cost), over the horizon. Sure, that's a few years or even decades down the line, but when your military operates on the principle of always having the technological upper hand (which is exactly how the US military works), investing in tech that is 10+ years away is a rather sound move. Not to mention the other applications rail technology could have, like space travel.

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"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
Re:Old news... by treeves · 2012-10-01 10:48 · Score: 2

Ahead flank, cavitate!

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...the future crusty old bastards are already drinking the Kool-Aid.
Re:Old news... by viperidaenz · 2012-10-01 11:11 · Score: 3, Informative

Things may be a little different if "gun range" is more than 100 miles
Did you miss the part about 220 mile range?
Re:Old news... by sjames · 2012-10-01 11:24 · Score: 2

It will travel at 3.4 km/s but orbital speed at sea level is about 8 km/s so it will drop relative to the ground if fired at 0 degrees elevation. The calculations will have to consider the curvature of the Earth and the elevations will be small but existent to hit targets over the horizon.
It is by definition a ballistic projectile and it will necessarily be fired over a curved surface.
Re:Old news... by AK+Marc · 2012-10-01 11:27 · Score: 2

It's not hard. I watched them build a building that was 20+ stories high our of legos (pre-fab sections that snap together). They support the weight of a good-sized building and just snap together. And that's boring commercially available tech.

The argument "I can't think of it, so it must be impossible" is the most given argument I see on Slashdot that doesn't have a name (strawmen, ad hominems being the most popular, but having names).

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Learn to love Alaska
Re:Old news... by khallow · 2012-10-01 13:11 · Score: 2

a rapid fire rail gun with a 110 m range would be a great for defense.
Unless a highly populated region happens to be on the other side of the missile targets. The current Phalanx ammunition has the virtue that it loses a lot of its velocity quickly. That's why its range is so short. But in compensation one doesn't usually have to worry about massive random collateral damage.

Re:Wow by Valor958 · 2012-10-01 08:26 · Score: 3, Interesting

Well... they need to drive interest since they just laid off some 160 people from their West Chester, Ohio plant.
http://www.wcpo.com/dpp/news/region_north_cincinnati/west_chester/bae-systems-to-lay-off-about-160-employees-at-west-chester-site
I know about this since I live very close by.

Technology improving warfare! by jellomizer · 2012-10-01 08:31 · Score: 4, Funny

Say it ain't so!

Hey look Ugg. Your club hurts, but I added a rock to the end of mine. Oh yea, well I have made a thinner club with a pointy edge to it so I can throw it at a distance. Oh yea. I put a sharp stone at the end of it so it will cut into my enemy further (and yes it has hunting applications too).

oh yea. Well I now can launch it with an other stick.
Heck I beat you with a more compact stick on a string.
By the way I have found to put sharper rocks at the end of sticks...

Hey check this out I found out how to melt rocks into this shiny stuff that doesn't shatter like a rock does, and I can grind it to make it sharper.

Yea I took your idea and made mine longer.

Yea, Well mine is sharper and better balanced.

Hey I just came back from China, I found this neat stuff that explodes.

Yea. I found I could make the direction better if I encase it metal that can contain and direct the explosion.

Well mine is bigger.

Well mine is more portable.

Well mine is more accurate.

Well mine can reload faster.

Well mine I can mass produce.

Well my big ones explode more.....

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If something is so important that you feel the need to post it on the internet... It probably isn't that important.

Re:Technology improving warfare! by evil_aaronm · 2012-10-01 08:41 · Score: 4, Insightful

You can take people out of the stone age, but you can't take the stone age out of the people.

Old holes... by Ostracus · 2012-10-01 08:38 · Score: 2

The power source is now a black hole. Oh wait! Skip the gun and throw the black hole at the target.

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Shai Schticks:"You don't make peace with friends, you make peace with enemies"

You missed one. by Anonymous Coward · 2012-10-01 08:44 · Score: 4, Insightful

You missed one MAJOR feature: cost.

New warfare is going to be all about cost. Nations/organizations battling on a ROI factor.

Case in point - Al Qu--whatever. They got a lot of dipshits who will die for Allah or whatever and they're giving the US a run for their money in those shitholes they're fighting in.

The US has all this high tech hardware that's been proven almost useless - the DRONES are being proven USEFULL.

You got a $190,000,000 aircraft? I got a 10 $10,000,000 aircraft that has a BETTER chance of shooting down the entire squadron of the $190M aircraft. You got ONE F-22 and a bunch of F-15s? So? I got 20+ Migs with assholes who'll die at any means to take YOU out.

And live to see another day.

President Eisenhower wasn't so far off (military industrial complex stuff), but he missed the fact of many many very poor people pissed off at the US for various reasons - and they'll die to hurt us.

People don't get it. They don't. Mitt RMoney is a moron. Obama sort of gets it.

Re:You missed one. by Martin+Blank · 2012-10-01 10:32 · Score: 4, Interesting

I don't think so. I don't know for sure that the $190M F-22 is six times better than a $30M F-15, but it's a lot more than 19 times better than the MiGs it's likely to face. Oh, maybe not the MiG-29, where it's perhaps only eight or ten times better, but the F-22 has the ability to knock you down from 60 miles out (around 100 miles when the AMRAAM-D comes along). Even one F-22 and a few F-15s would make short work of 20+ MiGs at $10M each since at that price, you're using comparatively ancient MiG-23s and not even MiG-29s, which cost three times as much.
Besides, the factor you missed is AWACS. That's a force multiplier of unbelievable proportion. Iraq learned that the hard way twice. When you have someone watching your back for missiles and aircraft from that far away who isn't likely going to get distracted because someone took a shot at him, it's a powerful ally. Knowing which group of enemy aircraft to target, where SAM sites are, how long an enemy aircraft has been flying (and thus how much fuel they might have left), and other tactical information helps enormously, and anyone fielding F-22s is going to have one or two AWACS planes up there guiding things.

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You can never go home again... but I guess you can shop there.

Explosives by ShakaUVM · 2012-10-01 08:47 · Score: 4, Funny

""Imagine a warship weapon that can launch projectiles at Mach 10 without explosives..."

Well, that's not counting the railgun itself, I guess.

They tend to fail spectacularly.

Re:speed /= kinetic energy by confused+one · 2012-10-01 08:50 · Score: 2

No, speed^2 * mass = kinetic energy.

Re:What's old is new again by Antipater · 2012-10-01 08:55 · Score: 2, Informative

Railgun

vs. Railroad Gun

Really?

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Everything is better with chainsaws.

Amazing by musth · 2012-10-01 09:14 · Score: 3, Insightful

No reflection at all about the deep problems that our obsession with inflicting violence on other people has got us into.

If all-holy technology is used to build a bigger, faster something - even if it's a terrifying weapon in the hands of a murderous empire like the US - then slaver over it on Slashdot. Because its about technology, and its about the gunz, and it has to be cool.

Re:really ? by Anubis350 · 2012-10-01 09:25 · Score: 2

Good thing this is the USN then.

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"goodbye and hello, as always" ~Prince Corwin, from Zelazny's Amber series

Re:How high can it shoot? by Deadstick · 2012-10-01 09:34 · Score: 4, Informative

You can't put anything in orbit with any gun, acting by itself. You must apply some thrust after the projectile reaches the desired height. If you don't do that, no matter how powerful the gun is, no matter how high the muzzle velocity is, no matter where you point it, one of two things will happen: it will hit the earth before completing one orbit, or it will fly away and never come back.

If you want to launch to orbit from a gun, you have to provide a rocket motor on the projectile that starts up at the appropriate point in the trajectory.

Here's another way to express it: you cannot achieve a repeating orbit whose low point (perigee) is higher than the last point at which thrust was applied. For a simple gun, that point is the muzzle.

Over the horizon rail guns? by erice · 2012-10-01 09:40 · Score: 2

You can't hit an object 220 miles away surface to surface by firing in a straight line. There's a big ball of rock and water in the way. If you have to fire in a balistic arc, is the high velocity of a rail gun of much use?

Re:Over the horizon rail guns? by adri · 2012-10-01 10:28 · Score: 2

.. i'd assume that whatever they were firing would have some kind of guidance control.
It's 2012. Why would you create a dumb ballistic projectile over that kind of distance?
Re:Over the horizon rail guns? by ceoyoyo · 2012-10-01 12:50 · Score: 2

Battleship shells still have to penetrate battleship armour kinetically when they arrive. They're designed to explode inside the target. Neglecting air resistance, an object travels at the same speed at the end of a ballistic trajectory as it does at the beginning. With air resistance, somewhat slower. A 200 nm ballistic trajectory would deliver a projectile with more speed than a flat trajectory, if such a thing were possible. The ballistic shell will spend much of it's time in thinner air at high altitude while the direct one would have to plow through sea level air the whole way.

Re:Fear it Iran by X0563511 · 2012-10-01 09:42 · Score: 4, Funny

Better than speaking big and carrying soft sticks.

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For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...

Re:How high can it shoot? by bobbied · 2012-10-01 10:16 · Score: 2

Here's another way to express it: you cannot achieve a repeating orbit whose low point (perigee) is higher than the last point at which thrust was applied. For a simple gun, that point is the muzzle.

Wow... Excellent point! Rail guns are pretty worthless on their own when trying to achieve a useful orbit. I suppose you could do some tricks with aerodynamics to help adjust the perigee up, but you are only going to be able to adjust the perigee (best case) to a point where enough air exists to apply the necessary force. This perigee will still be in the atmosphere, meaning the orbit will not be lasting due to air resistance.

Mod Parent UP!!

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Re:How high can it shoot? by Anonymous Coward · 2012-10-01 10:28 · Score: 3, Informative

Technically that is not accurate.

You could (theoretically) fire a ballistic projectile at an escape velocity and at such an angle that the atmosphere will slow it down to be an orbital velocity. You could also fire and use a gravitational slingshot to put an object in orbit.

Thrust is not the only means of changing a ballistic trajectory into an orbit, both drag and gravity work as well.

The first point here also means you cannot really have a perfect ballistic trajectory inside an atmosphere.

Re:Hmm, should rather be used by viperidaenz · 2012-10-01 11:45 · Score: 2

Imagine something useful, like a communications satellite, you'd want to place in orbit. Maybe it weighs 100kg. Now imagine crushing it with a 12,000,000kg weight. That's sort of what happens when you try and accelerate it at 1,200,000m/s/s. Also of note, escape velocity is 11,200kph. Mach 10 may be slightly faster than that, but shooting something at 11,200kph will only make it out of Earth's gravitational pull if friction is not taken in to account. You need to factor in 160km of atmosphere causing friction.

Re:Side-track. by Kittenman · 2012-10-01 12:05 · Score: 2

Wonderful! First our video games are on rails. Now our guns are.

Just as long as it's not Ruby...

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"The greatest lesson in life is to know that even fools are right sometimes" - Winston Churchill

Re:really ? by downhole · 2012-10-01 12:14 · Score: 4, Insightful

Not sure if GP was serious or not, but looks to me like the modern US Army and other armed forces go to an unbelievable and completely unprecedented amount of effort to avoid collateral damage compared to every other military force that has ever existed. Those who seriously complain about it either have no idea what they're talking about, or are pursuing an anti-American agenda and don't have the courage to be straightforward about it.

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I don't reply to ACs

Re:How high can it shoot? by rubycodez · 2012-10-01 12:19 · Score: 4, Interesting

wrong. there are trajectories in a multi-bodied system such as the earth-moon one where orbit can be achieved. your teacher or urban-legend websource was only considering the earth as a lone body.

Re:How high can it shoot? by Deadstick · 2012-10-01 12:30 · Score: 2

your teacher or urban-legend websource was only considering the earth as a lone body.

No, *I* was considering this as a pure two-body problem because any three-body solution to getting a projectile into LEO would involve a ridiculous amount of energy.

Re:Needs a name by INeededALogin · 2012-10-01 13:10 · Score: 3, Insightful

... they are, after all, just a bunch of weirdly drawn cartoons... I know the white man-toddlers... like to call it "anime"... they are cartoons. For kids.

You do know that it is the Japanese who call it anime and that anime is short for animation so yes... by definition of the word "anime" they are cartoons. Good attempt to try and attribute the anime term to white fanboys.

Oh, I don't even watch anime, but people enjoy it so why be a douche about it.

Not a problem by ridgecritter · 2012-10-01 14:58 · Score: 3, Informative

Doing it from a ship or land based gun will give you problems because the Earth has this curvature, and your hypersonic dart is pretty much going to travel in a straight line. So things that are over the horizon are pretty much out of reach since drilling straight through the Earth is not really practical.

These projectiles will certainly be guided (http://www.popsci.com/technology/article/2012-08/its-experimental-rail-gun-navy-wants-gps-guided-hypersonic-projectiles) with accuracies at least as good as current ICBM systems, and probably as good as existing precision bombing systems like JDAM (http://en.wikipedia.org/wiki/Joint_Direct_Attack_Munition) and others. There are plenty of ways to guide a very fast munition that do not require sticking control surfaces out in a hypersonic air stream.

Re:speed /= kinetic energy by yo303 · 2012-10-01 20:16 · Score: 2

No, one half of speed^2 * mass = kinetic energy.

Re:Fear it Iran by ImprovOmega · 2012-10-02 04:29 · Score: 2

He's making a joke about the movie "Eraser" where the bad guys were armed with "portable railguns" (at one point die governator is shooting one from each hand) that somehow can fire rounds accelerated to a tenth or so of the speed of light, can fire multiple times per second, for several minutes, without reloading/recharging, that knock someone back 50 feet on impact, and yet somehow there's virtually no recoil for the use of said device.

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