Navy prepares to take railguns to sea

[Teln]

http://arstechnica.com/information-technology/2014/04/navy-prepares-to-take-rail-gun-to-sea/

Navy prepares to take railgun to sea
General Atomics- and BAE-built guns will be tested on high-speed vessel in 2016.

by Sean Gallagher - Apr 8 2014, 11:40am EST
http://cdn.arstechnica.net/wp-content/uploads/2014/04/railgun.jpg
The General Atomics Blitzer, one of two railguns being tested by the US Navy at Dahlgren, Virginia.

The US Navy has completed another round of tests in its quest for the ultimate ship’s gun: a functional weapon based on railgun technology. The next step is to take the gun to sea for tests aboard the USNS Millinocket (JHSV 3), a high-speed transport catamaran built by Austal. “We’re beyond lab coats—we’re into engineering now,” said Chief of Naval Operations Admiral Jonathan Greenert during a speech at the Navy League’s Sea-Air-Space Expo in National Harbor, Maryland.

The railgun is just one of a number of high-energy weapons being tested by the Navy. The first to go to sea will be the Laser Weapon System (LaWS), which will be put to sea aboard the USS Ponce late this summer, the Office of Naval Research confirmed yesterday.

But the LaWS is a relatively low-power directed energy weapon intended to take out drones, small boats, and other threats at fairly close range. The electromagnetic rail guns, which are being tested at the Naval Surface Warfare Center’s Dahlgren Division in Dahlgren, Virginia, are capable of launching a projectile at speeds over Mach 7 and would have ranges exceeding 100 miles. A 23-pound projectile flying at Mach 7 has 32 megajoules of energy. That’s roughly equivalent to the energy required to accelerate 1,000 kilograms (1.1 US tons) to 252 meters per second—or around 566 miles an hour.

A video released yesterday by the Naval Sea Systems Command shows the completion of railgun test shots against a number of targets, including a dummy missile warhead and multiple reinforced concrete walls. The Navy has tested two railguns—one built by General Atomics, the makers of the Predator drone, and one built by BAE Systems. Both will be put aboard the Millinocket this summer for demonstration, but the Navy will choose just one for the final test.


https://www.youtube.com/watch?v=Htszh_6Sl1s

Wow. Such gun. Many boom. Wow.

[Eldan]

Huh. I never knew Railguns produced giant fiery explosions. I always thought they'd look... I don't know. More scifi. A sonic boom, sure. But not a cloud of burning gas.

[CarpeGuitarrem]

Huh. I never knew Railguns produced giant fiery explosions. I always thought they'd look... I don't know. More scifi. A sonic boom, sure. But not a cloud of burning gas.
Sort of a whirr, flash of light, and instant annihilation?

[Mando Knight]

US Navy: Building tomorrow's space-guns for today's ships.

[Eldan]

Sort of a whirr, flash of light, and instant annihilation?

More boom and flash, but yes. I'm not even sure what's exploding in there... as far as I know they don't have any kind of propellant. Sure, the rails probably get very, very hot, but what is it that's burning?

[Madcrafter]

More boom and flash, but yes. I'm not even sure what's exploding in there... as far as I know they don't have any kind of propellant. Sure, the rails probably get very, very hot, but what is it that's burning?If I remember correctly, it's probably either because the electrical arc is vaporizing the outside of the sabot into a plasma, or the railgun itself is using an ionized gas as the propellant instead of a magnetic shell/sabot, which looking at the round a little closer doesn't seem to be the case. You can get plasma flashes with even tiny railguns, see this one (http://www.youtube.com/watch?v=N0F6r0Mf_iM).

[erikun]

More boom and flash, but yes. I'm not even sure what's exploding in there... as far as I know they don't have any kind of propellant. Sure, the rails probably get very, very hot, but what is it that's burning?
Speed, friction, mass and inertia.

Note that the standard gun fires a bullet weighing several grams (a fraction of an ounce) at generally around the speed of sound (mach 1). A railgun generally fires ammo weighing several kilograms (several pounds) at speeds around 5000 mph (mach 6.5). Simply running into something with that much speed, and that much mass, causes a lot of damage. All the fire and light is what happens when you take all that kinetic energy, and try turning it into heat - basically what happens when its speed is dropped to zero from hitting a target.

[BWR]

Much though I love my sci-fi (and SCIENCE! is a good enough reason to build something like this), what advantages does this have over traditional chemically propelled stuff?

[hamishspence]

Much though I love my sci-fi (and SCIENCE! is a good enough reason to build something like this), what advantages does this have over traditional chemically propelled stuff?

Flatter trajectory - so less complicated aiming?

[Sith_Happens]

http://24.media.tumblr.com/f9ab2a7a796e52c686d70031e6c1aa31/tumblr_mocifbAP751s0hia6o1_250.gif


Much though I love my sci-fi (and SCIENCE! is a good enough reason to build something like this), what advantages does this have over traditional chemically propelled stuff?

One-shotting office-building-sized Decepticons at maximum targeting range, for a start.:smalltongue:

[Eldan]

http://24.media.tumblr.com/f9ab2a7a796e52c686d70031e6c1aa31/tumblr_mocifbAP751s0hia6o1_250.gif



One-shotting office-building-sized Decepticons at maximum targeting range, for a start.:smalltongue:

But couldn't a chemical missile do that too? Plus carry specialized warheads, guidance equipment and probably longer range?

[Sith_Happens]

But couldn't a chemical missile do that too? Plus carry specialized warheads, guidance equipment and probably longer range?

They do take out that one scorpion-looking Transformer with an anti-tank round in the first movie... And then never try it again, even though Main Soldier Character specifically says into his radio "Target is vulnerable to HEAT rounds" when it works the first time.:smallsigh:

[supermonkeyjoe]

But couldn't a chemical missile do that too? Plus carry specialized warheads, guidance equipment and probably longer range?

I'm guessing the fact that railgun projectiles travel at over twice the speed of most of the fastest missiles and mover 7 times the speed of subsonic missiles mean there's not a lot of chance to dodge them, they literally hit you before you hear the gun go bang.

[BWR]

I thought most projectiles you might conveivably dodge already travel at mach or better.

[CarpeGuitarrem]

They certainly mach a big mess.

[SiuiS]

Huh. I never knew Railguns produced giant fiery explosions. I always thought they'd look... I don't know. More scifi. A sonic boom, sure. But not a cloud of burning gas.

The secondary flash looks to be whatever is used to separate the missile from its casing. The primary is probably just a combination of air and immense friction. I'm totally with you on being surprised though.


Speed, friction, mass and inertia.

Note that the standard gun fires a bullet weighing several grams (a fraction of an ounce) at generally around the speed of sound (mach 1). A railgun generally fires ammo weighing several kilograms (several pounds) at speeds around 5000 mph (mach 6.5). Simply running into something with that much speed, and that much mass, causes a lot of damage. All the fire and light is what happens when you take all that kinetic energy, and try turning it into heat - basically what happens when its speed is dropped to zero from hitting a target.

The muzzle flash, not the impact. As the projectile leaves the barrel is is kissed goodbye by an explosion of fire. That explosion of fire is traditionally from the decompressing superheated gasses of a chemical projectile, and is part of what accelerates the missile.

If the missile is being accelerated purely by electricity, why is there an explosion? The plasma idea sounds most accurate.

[Chen]

Much though I love my sci-fi (and SCIENCE! is a good enough reason to build something like this), what advantages does this have over traditional chemically propelled stuff?

The projectile can be simpler. If you get the speed high enough, you really just need a slug of metal to do enough damage. You don't need complex warheads in that case which presumably makes it a fair bit cheaper. Also makes the ship safer without needing it to carry around a bunch of explosive chemicals for launching its weapons.

[Cikomyr]

Damn it

why do weapons have to be so COOL?


Okay. I think I have to ask the question EVERYONE is asking:

Do you think this gun can take down Superman?

[Madcrafter]

The projectile can be simpler. If you get the speed high enough, you really just need a slug of metal to do enough damage. You don't need complex warheads in that case which presumably makes it a fair bit cheaper. Also makes the ship safer without needing it to carry around a bunch of explosive chemicals for launching its weapons.Mostly this I think. The round fired by that railgun costs approximately 25 000 USD, whereas a missile, while longer range (and slower), will put you back several hundred thousand at least. Plus they're smaller, and therefore easier to store, and as mentioned, don't have all that explosive stuff packed with them.

[Cikomyr]

Mostly this I think. The round fired by that railgun costs approximately 25 000 USD, whereas a missile, while longer range (and slower), will put you back several hundred thousand at least. Plus they're smaller, and therefore easier to store, and as mentioned, don't have all that explosive stuff packed with them.

Probably also harder to intercept with our most recent anti-missile interceptors.

[Mando Knight]

Mostly this I think. The round fired by that railgun costs approximately 25 000 USD, whereas a missile, while longer range (and slower), will put you back several hundred thousand at least. Plus they're smaller, and therefore easier to store, and as mentioned, don't have all that explosive stuff packed with them.

The LaWS interceptor laser is also being developed for its relatively cheap ammo: the energy costs apparently add up to about 1 USD per shot, making it a really cheap anti-missile/anti-drone weapon.

[Frozen_Feet]

Probably also harder to intercept with our most recent anti-missile interceptors.

They are flat-out impossible to intecept with current technology.

Oh, and the flames from the barrel are just the air. I'm amazed the projectile doesn't leave a flaming trail behind it for the whole journey.

[Cikomyr]

They are flat-out impossible to intecept with current technology.

Oh, and the flames from the barrel are just the air. I'm amazed the projectile doesn't leave a flaming trail behind it for the whole journey.

Yhea my point.

Bigger sword to break the bigger shield. But a bigger shield will come over eventually.

[Soras Teva Gee]

But couldn't a chemical missile do that too? Plus carry specialized warheads, guidance equipment and probably longer range?

A chemical rocket takes all those lovely electronics and blows them up. The bullets this thing fires are (IIRC) supposed to be substantially cheaper per shot. That's assuming the gun doesn't break all the time which previously had been quite a problem.

Of course by the same token its only going to be in a ballistics curve so this thing isn't really a replacement for missiles, its a more a replacement for the 5 in gun currently deployed then the VLS that is a modern smallboy's main armament.

Me I'm still not completely sold on this railgun CBA virture. I still smell an elephant gun.

[ace rooster]

The round cost $25000 because they only made a few. Once you start making more the price should drop considerably.

The fact it is increadably hard to stop is one thing, the fact that there is already another one coming is another. The actual energy density of explosives and propellants is quite low when compared to diesel, never mind nuclear. Each of the rounds being much smaller as well means that a ship can carry far more shots. All the fuel in the ship could go towards powering the gun, and a ship would never carry that much high ordinance. Even if it did it could not be stored as easily as diesel, or used for anything else.

The advantage over traditional chemical guns is a higher muzzle velocity. To apply pressure to a shell a conventional gun has to accelerate the gas it produces to the speed of the shell, which is limited by the speed of sound of the propellant. This gives a gun a maximal velocity. Imagine if there was no shell, and you fired a charge at the end of the barrel. The gas would accelerate to a particular speed, and if you put something in front of that gas it will not get pushed faster than the gas.
A railgun uses magnetic flux instead of gas to drive the shell, and magnetic flux is massless, so moves at the speed of light. This permits much higher velocities, with the speed of light being the only theoretical limit.

[Cikomyr]

Do the RailBullet have explosive tips?

[Soras Teva Gee]

The fact it is increadably hard to stop is one thing, the fact that there is already another one coming is another. The actual energy density of explosives and propellants is quite low when compared to diesel, never mind nuclear. Each of the rounds being much smaller as well means that a ship can carry far more shots. All the fuel in the ship could go towards powering the gun, and a ship would never carry that much high ordinance. Even if it did it could not be stored as easily as diesel, or used for anything else.

Yeah I get the impression you aren't very familiar with a 5" naval gun (http://en.wikipedia.org/?title=5%22/54_caliber_Mark_45_gun) are you? First off the shells are pretty trivial in weight at a mere 70 lbs. Next they already carry some 600 rounds already in a pretty modest space commitment. That works out to some 21 tons on ships that start at over 9000 tons. Under .2% isn't anything.

And for that sort of capacity... well you simply don't fire these kinds of weapons like a machine gun. So I think they have plenty.



The advantage over traditional chemical guns is a higher muzzle velocity. To apply pressure to a shell a conventional gun has to accelerate the gas it produces to the speed of the shell, which is limited by the speed of sound of the propellant. This gives a gun a maximal velocity. Imagine if there was no shell, and you fired a charge at the end of the barrel. The gas would accelerate to a particular speed, and if you put something in front of that gas it will not get pushed faster than the gas.
A railgun uses magnetic flux instead of gas to drive the shell, and magnetic flux is massless, so moves at the speed of light. This permits much higher velocities, with the speed of light being the only theoretical limit.

Yes I knew this.

Now apply one of the most basic rules of gun safety: Do not point your gun at anything you do not intend to shoot.

All that speed means you have potentially huge possible ranges, I've heard claims of hundred miles. Can you be sure that everything within a cone of several degrees extended out for a hundred miles is something you intend to shoot? Because you pointed a gun at it. Once you fire a ballistic projectile Sir Issac Newton makes it his sworn duty to ruin something's day. I hope and pray intended targets are not including aircraft unless there's a compelling argument for the words "over penetration" being 120% not an issue. I also question the precision possible for whatever is going to angle this gun at the proper degree and withstand the forces involved with firing it.

That's all almost besides the point because lets not forget that we have been busy not building the most fearsome guns possible since WWII wrapped up. Because planes and missile can be actively guided by someone other then that mad knight named Newton from any range you please.

There's a disconnect between safety, precision, and effectiveness that I have yet to see resolved in satisfactory detail.

[TheThan]

Nothing like a well aimed rock.


Damn it

why do weapons have to be so COOL?


Okay. I think I have to ask the question EVERYONE is asking:

Do you think this gun can take down Superman?


Naww, he’ll catch the projectile and throw it back at the same speed.

[ace rooster]

Yeah I get the impression you aren't very familiar with a 5" naval gun (http://en.wikipedia.org/?title=5%22/54_caliber_Mark_45_gun) are you? First off the shells are pretty trivial in weight at a mere 70 lbs. Next they already carry some 600 rounds already in a pretty modest space commitment. That works out to some 21 tons on ships that start at over 9000 tons. Under .2% isn't anything.

And for that sort of capacity... well you simply don't fire these kinds of weapons like a machine gun. So I think they have plenty.



Yes I knew this.

Now apply one of the most basic rules of gun safety: Do not point your gun at anything you do not intend to shoot.

All that speed means you have potentially huge possible ranges, I've heard claims of hundred miles. Can you be sure that everything within a cone of several degrees extended out for a hundred miles is something you intend to shoot? Because you pointed a gun at it. Once you fire a ballistic projectile Sir Issac Newton makes it his sworn duty to ruin something's day. I hope and pray intended targets are not including aircraft unless there's a compelling argument for the words "over penetration" being 120% not an issue. I also question the precision possible for whatever is going to angle this gun at the proper degree and withstand the forces involved with firing it.

That's all almost besides the point because lets not forget that we have been busy not building the most fearsome guns possible since WWII wrapped up. Because planes and missile can be actively guided by someone other then that mad knight named Newton from any range you please.

There's a disconnect between safety, precision, and effectiveness that I have yet to see resolved in satisfactory detail.

As you point out the range is huge, way beyond that of the 5 inch gun (20km). In that regard it is better compared to ship to ship missiles. To carry a charge that will relably do heavy damage to a ship over a range of hundreds of miles you need a big missile that flies efficiently. These can be and are defended against, and a cruiser will only carry about two dozen. The railgun is much harder to deal with, similarly to the 5 inch gun, and does not have to worry about wasting ammo.

Against aircraft you will still be much better with a missile. Hitting a fast moving target with an unguided projectile is always going to be hard, no matter how fast your projectile is going. Against ships you will be aiming to hit your target with an trajectory that will be descending at the target. You are not going to miss by a long way.

Newton is pretty reliable, and it is not like mistakes have never been made with missiles. Being committed at launch is not that much different from being committed at impact, especially if you can fire the gun 5 mins later and still strike the target at the same time. It was the range of missiles that made conventional guns obsolete, with their theoretical maximum muzzal velocity. Railguns do not have that particular limitation.

The shell itself is very light when compared to the 5 inch gun. This means that the forces are not much higher than in that. The targeting is harder, but is not anything new. Given that it is the same company that makes the 5inch gun, I don't see these being a huge problem.

You may not be convinced, but somebody who's job it is to ask these questions has decided it is time to try it on a ship.


To the person who asked about explosive tips, there is little point in using explosives when the kinetic energy per gram of projectile is far beyond the chemical energy tied up in the explosive. The low density of explosives would increase the air resistance of a projectile of the same mass which would actually lower the energy released at impact.

[Ravens_cry]

The reason rail guns make a flash like that is for the same reason space capsules make a big burning trail when they re-enter. They are punching the air so hard, so fast, it can't get out of the way fast enough, so it piles up and compressed in front, creating a tremendous amount of super hot gas, which expands as soon as it can.
Some of it is from friction from the rails, but a lot of it is because the bullet is punching the air.
And winning.

[Yora]

Do the RailBullet have explosive tips?

No, it's just a solid chunk of metal delivering a really powerful punch.

I'm not sure if you could even pack them with explosives and still have them survive the extreme acceleration when being fired.

[Soras Teva Gee]

As you point out the range is huge, way beyond that of the 5 inch gun (20km). In that regard it is better compared to ship to ship missiles. To carry a charge that will relably do heavy damage to a ship over a range of hundreds of miles you need a big missile that flies efficiently. These can be and are defended against, and a cruiser will only carry about two dozen. The railgun is much harder to deal with, similarly to the 5 inch gun, and does not have to worry about wasting ammo.

Checking again I'm again finding ranges at the 100 mi marker (http://www.military.com/daily-news/2014/01/10/future-destroyers-likely-to-fire-lasers-rail-guns.html?ESRC=todayinmil.sm) for range which is broadly comparable to a Harpoon or Exocet, but around a third of an F-18 running interdiction, and a tenth of a Tomahawk cruise missile.

I will also point out that for the wiki listed speed of 5,400 mph... should work out to 90 miles a minute right? Since a ballistic projectile largely by definition can't steer... well pick your range and see how many seconds you have to get out its path. You even suspect (and not like this is a secret weapon) you might come under fire and you just need to not follow a predictable straight line course. So a lot of that range boils right with basic measures, yes even ships you might be surprised how nimble they can be. Unless this railgun creates a more substantial wake of destruction behind it then I'm seeing in the test shots.

So this is for bombardment of stationary targets then? Have air supremacy and you can get just about anything to strike a stationary target. Even if you don't we have options like the Predator, which can be used for other tasks at longer range and carries a Hellfire that's running around only x3 times the cost per shot and is a missile. Is this down to hardened targets not worth cruise missile but convienent for bombardment from the sea?

Yeah its still strictly better then a 5" gun I guess... but those are already a tertiary weapon system lets not forget. Anyone claiming this railgun would be cheaper then that?


Newton is pretty reliable, and it is not like mistakes have never been made with missiles. Being committed at launch is not that much different from being committed at impact, especially if you can fire the gun 5 mins later and still strike the target at the same time. It was the range of missiles that made conventional guns obsolete, with their theoretical maximum muzzal velocity. Railguns do not have that particular limitation.

Mistake I tend to think from bad target identification, not missing and hitting something miles and miles away.

Care to run the trig to see how many fractions of a degree in the angle of the barrel are needed to make a difference when the sides of the triangle are 100 miles? Not to mention the mechanical challenge of having a system delicate enough for those minute adjustments but durable enough to survive the recoil without needing a couple hours of 3M to recalibrate.

And the range is still pretty obsolete. Cheaper per shot won't help if you start getting hit from outside it with missiles even if those missile are more expensive they're still going to be a lot cheaper then a boat.



You may not be convinced, but somebody who's job it is to ask these questions has decided it is time to try it on a ship.


I wouldn't have called it an "elephant gun" if that wasn't the case.

[Karoht]

Missiles and artillery shells also do things like propelling fragments at high speeds around the target area. We call this shrapnel.
A solid round which (in theory) is less likely to break apart also has value for more precision strikes. IE-House full of badguys next to house full of civilians. Notice how they seem to be going for pentration and impact velocity, explosive power doesn't seem to be a factor.
Of course, this is all still very early testing, and I'm making a few guesses based entirely on what I've seen and read. Which is very likely to be incomplete information.

[Eric Tolle]

Some of that "explosion" is likely vaporized portions of the rails. I wonder what the Navy intends to do about the "Can't fire more than a couple of shots due to rail erosion" problem. Maybe they have in mind a system for quickly replacing rails? Of course storing spare rails will take up space and weight.


Missiles and artillery shells also do things like propelling fragments at high speeds around the target area. We call this shrapnel.
A solid round which (in theory) is less likely tom making a few guesses based entirely on what I've seen and read. Which is very likely to be incomplete information.

Absent terminal guidance, I would not want to be in a house in the same neighborhood as the intended target of an artillery shell. Dumb railgun shells are going to be far less accurate then a guided missile, especially over-the-horizon ranges.

There's also the fact that a simple defense against railguns is simply to live more than a hundred miles from the coast. So it's most likely that the railgun is mostly intended for anti-ship and amphibious operation support.

[Madcrafter]

Mistake I tend to think from bad target identification, not missing and hitting something miles and miles away.

Care to run the trig to see how many fractions of a degree in the angle of the barrel are needed to make a difference when the sides of the triangle are 100 miles? Not to mention the mechanical challenge of having a system delicate enough for those minute adjustments but durable enough to survive the recoil without needing a couple hours of 3M to recalibrate.

And the range is still pretty obsolete. Cheaper per shot won't help if you start getting hit from outside it with missiles even if those missile are more expensive they're still going to be a lot cheaper then a boat.At 100 miles, approximately +/- .001 deg. to hit at 6m target (eg. a house sized building). At the same range, the broadside of a 155m destroyer would be +/- approximately .028 degrees. So it will take some fancy mechanics. A wonderful engineering problem.

Considering the projectiles themselves don't have a very large destructive area from all indications, I don't think they'd typically fire them at that range if they might miss. Which does lead to the problem you postulated above, with misses and/or over-penetration. It would not be easy to use them on ground targets.


Some of that "explosion" is likely vaporized portions of the rails. I wonder what the Navy intends to do about the "Can't fire more than a couple of shots due to rail erosion" problem. Maybe they have in mind a system for quickly replacing rails? Of course storing spare rails will take up space and weight.

I assume they have managed to fix or mitigate that problem, if they are going to mount them on ships. Replacing rails is not something I think you would want to do while at sea.

[ace rooster]

Checking again I'm again finding ranges at the 100 mi marker (http://www.military.com/daily-news/2014/01/10/future-destroyers-likely-to-fire-lasers-rail-guns.html?ESRC=todayinmil.sm) for range which is broadly comparable to a Harpoon or Exocet, but around a third of an F-18 running interdiction, and a tenth of a Tomahawk cruise missile.

I will also point out that for the wiki listed speed of 5,400 mph... should work out to 90 miles a minute right? Since a ballistic projectile largely by definition can't steer... well pick your range and see how many seconds you have to get out its path. You even suspect (and not like this is a secret weapon) you might come under fire and you just need to not follow a predictable straight line course. So a lot of that range boils right with basic measures, yes even ships you might be surprised how nimble they can be. Unless this railgun creates a more substantial wake of destruction behind it then I'm seeing in the test shots.

So this is for bombardment of stationary targets then? Have air supremacy and you can get just about anything to strike a stationary target. Even if you don't we have options like the Predator, which can be used for other tasks at longer range and carries a Hellfire that's running around only x3 times the cost per shot and is a missile. Is this down to hardened targets not worth cruise missile but convienent for bombardment from the sea?

Yeah its still strictly better then a 5" gun I guess... but those are already a tertiary weapon system lets not forget. Anyone claiming this railgun would be cheaper then that?



Mistake I tend to think from bad target identification, not missing and hitting something miles and miles away.

Care to run the trig to see how many fractions of a degree in the angle of the barrel are needed to make a difference when the sides of the triangle are 100 miles? Not to mention the mechanical challenge of having a system delicate enough for those minute adjustments but durable enough to survive the recoil without needing a couple hours of 3M to recalibrate.

And the range is still pretty obsolete. Cheaper per shot won't help if you start getting hit from outside it with missiles even if those missile are more expensive they're still going to be a lot cheaper then a boat.

I wouldn't have called it an "elephant gun" if that wasn't the case.

My understanding is that the expectation is for anti missile/anti air systems to become good enough that missiles will become an ineffective way to attack a naval force. At that point the rail gun becomes a primary anti ship weapon. Shorter range is fine if you cannot get effectively attacked at longer range. It is being developed for when laser tech makes missiles obsolete in navel settings. Currently it has no role.

Sure I will do the trig, but small angles always look tiny (visual acuity is about 0.016 degrees), so I will give you a way of visualising the uncertainties:
For an 8m barrel, placing the end to within 1mm (not hard with modern systems) gives a shot within 20m at 100miles, on a pretty flat trajectory (which makes uncertainties in range and power less important). Not a guarenteed kill, but you are not limited to one shot. Certainly accurate enough to worry a carrier, which will be stuck on a heading if landing aircraft. Forcing a carrier to withdraw will make getting air superiority much easier, and then your aircraft attack the land targets (mostly still with missiles).

I suppose I agree that it could be called an elephant gun, but I disagree that this is an insult. It is just a reflection of the fact that military planners think that at some point they may have to go elephant hunting. (due to ships getting a thick hide if you want to push the metaphor)

[Soras Teva Gee]

At 100 miles, approximately +/- .001 deg. to hit at 6m target (eg. a house sized building). At the same range, the broadside of a 155m destroyer would be +/- approximately .028 degrees. So it will take some fancy mechanics. A wonderful engineering problem.


In other words we'll want to add some kind of rig to hold this thing stable by countering motion of the ocean too.

Now from a research and engineering perspective this is all fascinating and awesome. All this stuff will be useful to someone someday, but that's the value of basic research. I'm not sure its worth deploying as ship based weapon. They knock it down to tank or plane level and we can be talking.


I assume they have managed to fix or mitigate that problem, if they are going to mount them on ships. Replacing rails is not something I think you would want to do while at sea.

Well depending on the weight you could do it. The VLS system has/d a crane option so its possible to build a collapsible system presuming these rails aren't so light you just need a GMSN on a ladder.

Its not something I'd think could be made very fast.


My understanding is that the expectation is for anti missile/anti air systems to become good enough that missiles will become an ineffective way to attack a naval force. At that point the rail gun becomes a primary anti ship weapon. Shorter range is fine if you cannot get effectively attacked at longer range. It is being developed for when laser tech makes missiles obsolete in navel settings. Currently it has no role.

Given that current thinking on missile engagements resembles something like a polite pistol duel with only a couple of shots at a time I think the real response will not be a reversion to ballistic projectiles but a transition to missile spam tactics and swamp the system. Well in a proverbial "total war" like we haven't had since WWII anyways.

I do see good potential in that laser system they're working on as a CIWS replacement/supplement. If only because you'd just shoot space if you miss. Then there's how many units you would need or could find space for and keep powered, especially given a horizon limited range.

I consider an actually perfect shell of laser point-defenses out there with someone making an effective reflective/refractory coating and painting sea skimming missiles with it.


Sure I will do the trig, but small angles always look tiny (visual acuity is about 0.016 degrees), so I will give you a way of visualising the uncertainties:
For an 8m barrel, placing the end to within 1mm (not hard with modern systems) gives a shot within 20m at 100miles, on a pretty flat trajectory (which makes uncertainties in range and power less important). Not a guarenteed kill, but you are not limited to one shot. Certainly accurate enough to worry a carrier, which will be stuck on a heading if landing aircraft. Forcing a carrier to withdraw will make getting air superiority much easier, and then your aircraft attack the land targets (mostly still with missiles).

A carrier's combat radius (http://en.wikipedia.org/wiki/Combat_radius) via aircraft still exceeds the railgun's stated range estimates by a comfortable amount. You manage to sneak in close enough and (passively) detect your target well enough to get a heading... knock yourself out.

Otherwise well for one flight ops won't be happening if you are in range to fire on them for that exact reason. And they won't be happening in moments because an immediate course change will be standard procedure on the assumption you've either fired or about to fire. Similar drills are already in place to counter torpedoes. And don't be thinking an aircraft carrier ain't as nimble (http://upload.wikimedia.org/wikipedia/commons/7/70/US_Navy_060111-N-1229B-002_The_Nimitz-class_aircraft_carrier_USS_Abraham_Lincoln_%28CVN_ 72%29_makes_a_high_speed_turn_during_the_ship_hand ling_drills.jpg) as its smaller cousins.

And firing repeatedly won't really help, you've got to close the range. Meanwhile well... carriers are like that popular kid in school. Always got a posse of hangers on.



I suppose I agree that it could be called an elephant gun, but I disagree that this is an insult. It is just a reflection of the fact that military planners think that at some point they may have to go elephant hunting. (due to ships getting a thick hide if you want to push the metaphor)

I think you don't need a railgun to hunt elephants and I don't approve of hunting white ones.

[Cikomyr]

How about space-based railguns? Used as orbital bombing platforms, the actual range of this weapon seems to be similar to the orbit of the ISS.

[Sith_Happens]

Mostly this I think. The round fired by that railgun costs approximately 25 000 USD, whereas a missile, while longer range (and slower), will put you back several hundred thousand at least. Plus they're smaller, and therefore easier to store, and as mentioned, don't have all that explosive stuff packed with them.

I kind of want to ask how a glorified ingot can still cost 25k, but making it able to survive being fired from this thing is probably no easy task.

[Lord Torath]

Recoil will be killer in space. On earth, you've got the land or the mass of a huge ship and the resistance of the water to counter the momentum of the shell. In space, there's nothing but your thrusters. Not saying it's impossible, but every shot is going to provide a huge impulse, altering your trajectory. You need some way to counteract that or your platform will be put in a different orbit every time you fire. Gyros will prevent it from sending you spinning, but won't help with the recoil.

As for Missile Spam, has anyone read Red Storm Rising? The Soviets make several "spam" missile attacks against the NATO naval forces, assuming roughly 1 in 3 missiles will make it through to hit a target. And that was with 1985 anti-missile technology. By now you're probably looking at about 1 in 10.

[Mando Knight]

I kind of want to ask how a glorified ingot can still cost 25k, but making it able to survive being fired from this thing is probably no easy task.

That's a sabot, not an ingot. The actual projectile is probably a super-high precision-cast/machined tungsten or nickel alloy slug. It's the finned missile-shaped thing that rips through everything in the images.

And yes, high-precision work with those kinds of metals can actually cost that much.

How about space-based railguns? Used as orbital bombing platforms, the actual range of this weapon seems to be similar to the orbit of the ISS.
As an orbital bombardment weapon? Forget the railgun bit, use a telephone pole sized tungsten rod and just drop the thing. Use a throwaway computer (cheaper than the rod it's guiding) and some fins for guidance, and it'll slam into whatever you point it at like a bunker-buster nuclear weapon.

[Cikomyr]

I kind of want to ask how a glorified ingot can still cost 25k, but making it able to survive being fired from this thing is probably no easy task.

Since it has to resist being shot at Mach 5 and still remain precise to hit a 5-m target 370 km away, I think there is some serious quality-verification process going on.

[Soras Teva Gee]

As for Missile Spam, has anyone read Red Storm Rising? The Soviets make several "spam" missile attacks against the NATO naval forces, assuming roughly 1 in 3 missiles will make it through to hit a target. And that was with 1985 anti-missile technology. By now you're probably looking at about 1 in 10.

Not changed nearly as much as one might think. Relative upgrades can be a mere 20 years old for military hardware.

Also the seminal example of that in said book was when the Russians shot more missiles then the AEGIS ship in question had... period. Can't fire more missiles then you got no matter how good they are. Something else that hasn't changed terribly much.

[Madcrafter]

That's a sabot, not an ingot. The actual projectile is probably a super-high precision-cast/machined tungsten or nickel alloy slug. It's the finned missile-shaped thing that rips through everything in the images.

And yes, high-precision work with those kinds of metals can actually cost that much.Indeed, casting and machining on a critical object like that can cost a lot. Last thing they want to do is ruin a gun prototype by having their slug go awry.

It's partially the same principle behind why a bolt in an aircraft might cost up to a hundred dollars, when you can buy something that looks exactly the same at the hardware store for a few cents.


As an orbital bombardment weapon? Forget the railgun bit, use a telephone pole sized tungsten rod and just drop the thing. Use a throwaway computer (cheaper than the rod it's guiding) and some fins for guidance, and it'll slam into whatever you point it at like a bunker-buster nuclear weapon.The Rods from God have more than a few technical problems, but yeah, if you're coming from space, you don't need a piddly accelerator cannon. You have the earth.

[Cikomyr]

Indeed, casting and machining on a critical object like that can cost a lot. Last thing they want to do is ruin a gun prototype by having their slug go awry.

It's partially the same principle behind why a bolt in an aircraft might cost up to a hundred dollars, when you can buy something that looks exactly the same at the hardware store for a few cents.

The Rods from God have more than a few technical problems, but yeah, if you're coming from space, you don't need a piddly accelerator cannon. You have the earth.

The problem with the Rods from God is that it will cost a ****ton of money to actually GET UP THERE.

for the same amount of rocket fuel, you can potentially load up twenty times as many railgun ammo.

[warty goblin]

The problem with the Rods from God is that it will cost a ****ton of money to actually GET UP THERE.

for the same amount of rocket fuel, you can potentially load up twenty times as many railgun ammo.

Or you just build a big heavy rocket and fire it from a launch platform here on Earth. You get the same amount of energy, don't need to fuss around with a launch station, the need to be able to maneuver the launch station into a launch window,the second set of rocket engines to 'drop' the rod from orbit, and just generally make life a lot easier for yourself.

[Yora]

Also the seminal example of that in said book was when the Russians shot more missiles then the AEGIS ship in question had... period. Can't fire more missiles then you got no matter how good they are. Something else that hasn't changed terribly much.

But then the attackers are out of missiles and can't continue their attack. Taking out a single target with overwhelming force should always be possible, but in most scenarios, taking out a specific target it a means to a much more complex end.

[Yora]

I will also point out that for the wiki listed speed of 5,400 mph... should work out to 90 miles a minute right? Since a ballistic projectile largely by definition can't steer... well pick your range and see how many seconds you have to get out its path. You even suspect (and not like this is a secret weapon) you might come under fire and you just need to not follow a predictable straight line course. So a lot of that range boils right with basic measures, yes even ships you might be surprised how nimble they can be. Unless this railgun creates a more substantial wake of destruction behind it then I'm seeing in the test shots.
Many warships can steer and evade crazy fast (http://www.youtube.com/watch?v=mzveUz-WRGQ&feature=youtu.be&t=48s). If you're used to ferries and cargo ships, it shouldn't even be possible for a huge chunk of metal to turn anywhere near that fast.

[MLai]

So every single time Superman really throws a punch, there should be a humongous fireball enveloping his face?

[Cikomyr]

Or you just build a big heavy rocket and fire it from a launch platform here on Earth. You get the same amount of energy, don't need to fuss around with a launch station, the need to be able to maneuver the launch station into a launch window,the second set of rocket engines to 'drop' the rod from orbit, and just generally make life a lot easier for yourself.

Too slow and not precise enough.

[ace rooster]

In other words we'll want to add some kind of rig to hold this thing stable by countering motion of the ocean too.

Now from a research and engineering perspective this is all fascinating and awesome. All this stuff will be useful to someone someday, but that's the value of basic research. I'm not sure its worth deploying as ship based weapon. They knock it down to tank or plane level and we can be talking.



Well depending on the weight you could do it. The VLS system has/d a crane option so its possible to build a collapsible system presuming these rails aren't so light you just need a GMSN on a ladder.

Its not something I'd think could be made very fast.



Given that current thinking on missile engagements resembles something like a polite pistol duel with only a couple of shots at a time I think the real response will not be a reversion to ballistic projectiles but a transition to missile spam tactics and swamp the system. Well in a proverbial "total war" like we haven't had since WWII anyways.

I do see good potential in that laser system they're working on as a CIWS replacement/supplement. If only because you'd just shoot space if you miss. Then there's how many units you would need or could find space for and keep powered, especially given a horizon limited range.

I consider an actually perfect shell of laser point-defenses out there with someone making an effective reflective/refractory coating and painting sea skimming missiles with it.



A carrier's combat radius (http://en.wikipedia.org/wiki/Combat_radius) via aircraft still exceeds the railgun's stated range estimates by a comfortable amount. You manage to sneak in close enough and (passively) detect your target well enough to get a heading... knock yourself out.

Otherwise well for one flight ops won't be happening if you are in range to fire on them for that exact reason. And they won't be happening in moments because an immediate course change will be standard procedure on the assumption you've either fired or about to fire. Similar drills are already in place to counter torpedoes. And don't be thinking an aircraft carrier ain't as nimble (http://upload.wikimedia.org/wikipedia/commons/7/70/US_Navy_060111-N-1229B-002_The_Nimitz-class_aircraft_carrier_USS_Abraham_Lincoln_%28CVN_ 72%29_makes_a_high_speed_turn_during_the_ship_hand ling_drills.jpg) as its smaller cousins.

And firing repeatedly won't really help, you've got to close the range. Meanwhile well... carriers are like that popular kid in school. Always got a posse of hangers on.



I think you don't need a railgun to hunt elephants and I don't approve of hunting white ones.

A 10 meter platform on hydraulics at each corner would need to be precise to within .3mm. Easily within reach of modern systems. I can't find any hard info on the accuracy of specter gunships, but they are regarded as highly accurate, and that is firing a howitzer from a plane.

A long range anti ship missile will always be bigger than a short range anti missile missile, so a ship will always be able to carry more. If they can be made to work reliably then an attacker should run out first. Spam tactics just make this happen faster. Laser defenses just make the situation worse for the attacker, but are not the only card the defender has to play.

0% albido is monumentally difficult to achieve, and absorbsion of any laser energy is likely to destroy the coating, making reflecting a high energy pulse non-trivial. Lasers are not a game changer on their own, but contribute.

Range discussions are specific to this particular version, but there is no theoretical reason for a later gun to be limited to mach 7. A mach 10 gun would have double the range, and is within the technology. This is still an early version, and there is a lot of space for improvement.

The situations where a railgun is appropriate are where anti ship missiles are ineffective (for any reason), rendering the carrier's wide combat radius moot. If one side has railguns and the other does not, then they become the decider. The side without has no effective weapon that can match the range. Dancing (while impressively effective) will never prove a 100% effective defense, especially against focused fire, and shuts down a carrier anyway.

Will this situation occur, or will anti ship missiles prove impossible to defend against? I won't commit to an answer, but it seems foolish to rely on that being the case, and risk facing game changing tactics without a response.

This will be my last post on the matter, as I was meaning not to get drawn into a discussion on whether it is a worthwhile piece of military hardware or not...oops (I would actually agree that it is probably not required, but would not want to place a bet on that probably). My first post was not supposed to be related to the tactics of use at all, but answering somebodies question about why you could not get the same effect from a conventional gun. I will continue to try to answer questions about the technicalities of the gun though, including aiming it precisely.

[Ravens_cry]

So every single time Superman really throws a punch, there should be a humongous fireball enveloping his face?

Yep. And sonic boom that deafens (or worse) everyone near by, probably shattering windows as well.

[Yora]

A long range anti ship missile will always be bigger than a short range anti missile missile, so a ship will always be able to carry more. If they can be made to work reliably then an attacker should run out first. Spam tactics just make this happen faster. Laser defenses just make the situation worse for the attacker, but are not the only card the defender has to play.
One very important factor in US military doctrine would be to be decades ahead in technology than their enemies. There might be possible countermeasures against certain new weapons, but when only the US, the EU, Russia, China, and Japan have any access to these countermeasures, it's still a very effective weapon against pretty much anyone who could engage US forces. (EU and Japan are close long-term allies, and in a war against Russia or China everyone would lose with nothing to gain.)

[Cikomyr]

One very important factor in US military doctrine would be to be decades ahead in technology than their enemies. There might be possible countermeasures against certain new weapons, but when only the US, the EU, Russia, China, and Japan have any access to these countermeasures, it's still a very effective weapon against pretty much anyone who could engage US forces. (EU and Japan are close long-term allies, and in a war against Russia or China everyone would lose with nothing to gain.)

Also Poland and Turkey

[Wardog]

Yeah I get the impression you aren't very familiar with a 5" naval gun (http://en.wikipedia.org/?title=5%22/54_caliber_Mark_45_gun) are you? First off the shells are pretty trivial in weight at a mere 70 lbs. Next they already carry some 600 rounds already in a pretty modest space commitment. That works out to some 21 tons on ships that start at over 9000 tons. Under .2% isn't anything.

And for that sort of capacity... well you simply don't fire these kinds of weapons like a machine gun. So I think they have plenty.




In that case, one advantage may be logistics. Even if a ship doesn't need more ammo for a given mission, you will be able to stockpile more, and transport them more easily/efficiently (because you can put more in a truck, or the same number in a smaller truck) and safely (because they are inert). Plus, they will presumably have a much longer shelf-life, because there is no propellant to degrade.

And if an enemy shell hits your magazine, you don't have to worry about all your ammo blowing up.

[Admiral Squish]

In regards to the 'dancing' defense, wouldn't that problem be solved by just firing three shots at a time (one left, one right, and one right on-target)? If you were to space the shots appropriately, there would be no way the ship could move that wouldn't be into the path of an incoming projectile.

My understanding is that the railgun is to replace short-range missiles and artillery, while the laser systems are to provide an effective defense against incoming missiles, boats, and low-flying aircraft. In theory, once said laser defense systems become ubiquitous, the railgun will also be called to serve as the primary offense as well, since missile attacks will no longer be effective.

Another advantage is the war of dollars. If two sides engage, and one side uses rounds that cost 25000, and the other is using rounds that cost 100000, but both are equally effective, the guy who's using the cheaper rounds will be able to buy more rounds. He will also be able to use his savings to repair his ships, buy more ships, and fund further research, while the other guy's spending four times as much to keep up.

[Soras Teva Gee]

In that case, one advantage may be logistics. Even if a ship doesn't need more ammo for a given mission, you will be able to stockpile more, and transport them more easily/efficiently (because you can put more in a truck, or the same number in a smaller truck) and safely (because they are inert). Plus, they will presumably have a much longer shelf-life, because there is no propellant to degrade.

And if an enemy shell hits your magazine, you don't have to worry about all your ammo blowing up.

Well the actual heavy weapons of the world trend toward not blowing up unless it was intentional... for that exact reason. Not that you don't still treat them with caution and reverence, but for the inevitable lapses their pretty durable. However yes inert slugs would nominally be that much safer, though seem like they'd want a fair bit of careful handling anyways.

Imagine these railgun slugs and sabots getting misaligned in transport and what could happen in the barrel of the rail gun as a result.

Anyways its not that there aren't nominal improvements... but are those improvements worth the inevitable price increase over the 5" already in use?


In regards to the 'dancing' defense, wouldn't that problem be solved by just firing three shots at a time (one left, one right, and one right on-target)? If you were to space the shots appropriately, there would be no way the ship could move that wouldn't be into the path of an incoming projectile.

Key word is "appropriately" here.

If you had a laser type of attack with a continuous stream of firepower that could work, though it would need three independent systems. Course a laser can't be humanly dodged (on Earth) anyways but also inherently limited by the horizon, but that's besides the point. The problem with a ballistic projectile is that is has to intersect the target not only on the appropriate vector, but at the right time. Especially for a shot going this quickly over as much area, against so small a target. You have to be at an exact location within an exceedingly exact fraction of a second to ensure a hit.

If your dodging ship angles its rudder at 30 degrees versus 40 degrees that is going to be a different intersection in time even if you cross both potential courses with the same shot. If you could predict what course change your enemy was making the problem wouldn't exist... but the method to do this is?

The only way around this is to close the range. While so help me you can get reasonably accurate and still be ahead of current guns, its an improvement to an already tertiary part of modern naval warfare. Missiles, aircraft, and submarines will all still be playing the leading roles. The improvements are there... but is it worth the cost increase over the system its replacing?

My answer is no. Unless this is a lot cheaper then a 5" (shot and system) not a missile its not really worth all the hullabaloo.

(To say nothing of conversion costs and building programs needed around this. I read that only the now canned Zumwalts could have powered the railgun and the Navy is only just this year started work, again, on its real Arleigh Burke replacement. So will have to survive another decade+ of budget battles before one one is in service)

[ace rooster]

Well the actual heavy weapons of the world trend toward not blowing up unless it was intentional... for that exact reason. Not that you don't still treat them with caution and reverence, but for the inevitable lapses their pretty durable. However yes inert slugs would nominally be that much safer, though seem like they'd want a fair bit of careful handling anyways.

Imagine these railgun slugs and sabots getting misaligned in transport and what could happen in the barrel of the rail gun as a result.

The forces involved are already considerable, comparable to a normal gun. Unlike a normal gun they do not increase in the worst case scenario of a projectile jamming in the barrel (And this is no more likely). Using a flywheel type energy supply the energy can be easily dumped back into the flywheel, and in some designs this is inherent. They are less likely to explode in this fashion than an ordinary gun. You could get a slightly wonky shot due to aerodynamic forces after the projectile leaves the barrel, but this is not catastrophic (or any worse than a normal gun).


Anyways its not that there aren't nominal improvements... but are those improvements worth the inevitable price increase over the 5" already in use?



Key word is "appropriately" here.

If you had a laser type of attack with a continuous stream of firepower that could work, though it would need three independent systems. Course a laser can't be humanly dodged (on Earth) anyways but also inherently limited by the horizon, but that's besides the point. The problem with a ballistic projectile is that is has to intersect the target not only on the appropriate vector, but at the right time. Especially for a shot going this quickly over as much area, against so small a target. You have to be at an exact location within an exceedingly exact fraction of a second to ensure a hit.

If your dodging ship angles its rudder at 30 degrees versus 40 degrees that is going to be a different intersection in time even if you cross both potential courses with the same shot. If you could predict what course change your enemy was making the problem wouldn't exist... but the method to do this is?

The only way around this is to close the range. While so help me you can get reasonably accurate and still be ahead of current guns, its an improvement to an already tertiary part of modern naval warfare. Missiles, aircraft, and submarines will all still be playing the leading roles. The improvements are there... but is it worth the cost increase over the system its replacing?

My answer is no. Unless this is a lot cheaper then a 5" (shot and system) not a missile its not really worth all the hullabaloo.

(To say nothing of conversion costs and building programs needed around this. I read that only the now canned Zumwalts could have powered the railgun and the Navy is only just this year started work, again, on its real Arleigh Burke replacement. So will have to survive another decade+ of budget battles before one one is in service)

I'm going to count hitting a target in accuracy, so respond to that. Firstly there is no reason to limit shots to 3. A whole battlegroup can focus fire on one target so that it has to deal with more than 10 at a time, from multiple directions. Assuming the target can track that many small projectiles accurately enough that they can find the way to avoid them all, there is no guarentee that one exists. Each projectile will be at a low angle, say 5', so trace a line below 10m for 100m. Observing the altitude of a projectile wrong by 5m will move where you think you are safe by 50m, so finding holes in fire patterns would be hard. If they cannot track them they are relying on luck.

[Admiral Squish]

Okay, let's say you have an enemy ship moving at a constant speed. You fire at the enemy ship. They have options to avoid the round, slowing down, speeding up, turning one way or another. So, you can mitigate this by firing multiple shots at a time. You place rounds in four more spots, left, right, behind and in front of the predicted target, spaced in a fashion depending on the dimensions of the ship, such that if they move far enough to avoid round one in any of the given directions, they would be moving into the path of one of the other four. With appropriate computer assistance, such a spread would be relatively easy. Granted, it's not a fool-proof option, as a highly maneuverable ship could still move in an unpredictable-enough fashion to avoid it. But a small battery of railguns could make it very difficult to avoid the shots.

Also, your comment about it being a tertiary system is addressed by my above post. When the navy's laser defense system becomes ubiquitous and highly effective, missiles will be largely removed from the game. Missile spam might still be an option, up to a point, but it would be extremely expensive. Thus, the railgun suddenly becomes the primary form of engagement on the sea, and if we stay on top of development of the system, our guns will be able to fire faster rounds over longer range, allowing us to have the advantage of reach in such encounters.

Yes, the 5" is a cheaper option... right now. Because the tech's already been developed. The railgun will become significantly cheaper once we fully master the technology, simplify the design a bit, and devote more manufacturing to it.

[Soras Teva Gee]

I'm going to count hitting a target in accuracy, so respond to that. Firstly there is no reason to limit shots to 3. A whole battlegroup can focus fire on one target so that it has to deal with more than 10 at a time, from multiple directions. Assuming the target can track that many small projectiles accurately enough that they can find the way to avoid them all, there is no guarentee that one exists. Each projectile will be at a low angle, say 5', so trace a line below 10m for 100m. Observing the altitude of a projectile wrong by 5m will move where you think you are safe by 50m, so finding holes in fire patterns would be hard. If they cannot track them they are relying on luck.

You need to completely fill an area where in square meters your target could possibly be some 20-90 seconds into the future (depending on range) to guarantee a hit. Including not only for changes in direction, but speed as well. That's a single coordinated attack, after that you reset the problem and try again you don't really improve your odds just have more chances. More weight of fire obviously improves your odds but ten doesn't seem like enough to me. Care to prove me wrong by working out the math on potential area for the approximate ranges and see random chance will get you as the attacker. How many shots do you need to reach say 30% chance.

This situation has no tricks, or traps here just that deadly SOB Issac Newton and rolling dice. Its like cheating at Battleship!

...

Actually doesn't that doesn't matter... you've defaulted the argument to me because of course this strategy already demands heavily out numbering your opponent in terms of ships.

No cost efficiency there at all. You've lost the war.

[Teln]

You need to completely fill an area where in square meters your target could possibly be some 20-90 seconds into the future (depending on range) to guarantee a hit. Including not only for changes in direction, but speed as well. That's a single coordinated attack, after that you reset the problem and try again you don't really improve your odds just have more chances. More weight of fire obviously improves your odds but ten doesn't seem like enough to me. Care to prove me wrong by working out the math on potential area for the approximate ranges and see random chance will get you as the attacker. How many shots do you need to reach say 30% chance.

This situation has no tricks, or traps here just that deadly SOB Issac Newton and rolling dice. Its like cheating at Battleship!

...

Actually doesn't that doesn't matter... you've defaulted the argument to me because of course this strategy already demands heavily out numbering your opponent in terms of ships.

No cost efficiency there at all. You've lost the war.

All ships are not created equal. It's frightfully easy to get a situation where trading 5-10 ships for one enemy ship is worthwhile--sinking a carrier is worth just about any price you could care to name.

[ace rooster]

You need to completely fill an area where in square meters your target could possibly be some 20-90 seconds into the future (depending on range) to guarantee a hit. Including not only for changes in direction, but speed as well. That's a single coordinated attack, after that you reset the problem and try again you don't really improve your odds just have more chances. More weight of fire obviously improves your odds but ten doesn't seem like enough to me. Care to prove me wrong by working out the math on potential area for the approximate ranges and see random chance will get you as the attacker. How many shots do you need to reach say 30% chance.

This situation has no tricks, or traps here just that deadly SOB Issac Newton and rolling dice. Its like cheating at Battleship!

...

Actually doesn't that doesn't matter... you've defaulted the argument to me because of course this strategy already demands heavily out numbering your opponent in terms of ships.

No cost efficiency there at all. You've lost the war.

Sure I will do some maths on 50s (100km for a mach 6 gun). A 200m ship traveling at 20m/s (40knots) will travel it's length every 10s, so 5 times. Those fast turns that are so impressive slow the ship dramatically, and take longer than you think. It takes about 25s to turn 90 degrees, and another 25 to get up to speed (turning at low speed is slower). This means that the boat is limited to one manuever in the time it has. In 50 seconds either the boat has slowed down at some point, and is in a box about 3 boat lengths square, or it has not, and it is somewhere on an arc about 6 boat lengths wide. Each shot covers a line about 100m as discussed, so 12 shots can cover the arc. The box is harder, and requires about 50 shots for there to be no safe zones at all. This gives 20 shots required for a 30% chance of a hit. If the boat has a standing start, then you require considerably less, so you can assume that the boat will not want to slow considerably. This will increase the odds further.

Sure the area is big, about a square kilometer, but the side of a warship is also big. Two ships firing from the flanks into the middle can guarentee that at least one of them will face a big target.

Focus fire does not mean out number your opponent. It is simply the obvious response to an enemy's only defense being limited in capacity. Having 10 ships firing at you does not mean that you are alone, simply that they have made a tactical choice to focus on you for this particular salvo.

[Madcrafter]

It's funny how this actually turns into a game of battleship.

For a generalized equation for number of shots in the worst case scenario (lower bound), I would suggest:

n = pi*(Rs/v)2/b2 , where R is the range, s is target's max speed, v is the muzzle velocity of the round, and b is the beam of the target

For best case (upper bound), change b to L, the length of the target.

If you can manage to get more ships firing at wider angles, it will greatly reduce the number of shots in most cases.

[Soras Teva Gee]

All ships are not created equal. It's frightfully easy to get a situation where trading 5-10 ships for one enemy ship is worthwhile--sinking a carrier is worth just about any price you could care to name.

You can got a reasonable chance to at least mission kill a carrier with any modern warship already. Couple of decent holes in the flight deck and its an amphib until it gets back to port and is repaired. That's assuming of course you can sneak through its defensive screen undetected.

And no the railgun doesn't really help because the combat radius on an F-18 is over 300 nmi and (in theory) the F-35 will be over 500. According to wiki anyways. But that's higher then anyone is claiming for the railgun, never mind with enough weight of fire to ensure a hit. You'll need effectively perfect air defense just to handle the sailing just to get in range. So if you've nullified the entire airborne theater of battle then yeah your longer range gun will have a purpose because its suddenly WWI again.

Heck and that's still assuming the carrier doesn't just decide to bug out before you get that close. Though I guess a DDGN/CGN isn't an entirely unreasonable idea here it will have to be one to win that race, which is further costs of course.

...Or...

You can always just do the smart thing and build a submarine to kill a carrier.


Sure I will do some maths on 50s (100km for a mach 6 gun). A 200m ship traveling at 20m/s (40knots) will travel it's length every 10s, so 5 times. Those fast turns that are so impressive slow the ship dramatically, and take longer than you think. It takes about 25s to turn 90 degrees, and another 25 to get up to speed (turning at low speed is slower). This means that the boat is limited to one manuever in the time it has. In 50 seconds either the boat has slowed down at some point, and is in a box about 3 boat lengths square, or it has not, and it is somewhere on an arc about 6 boat lengths wide. Each shot covers a line about 100m as discussed, so 12 shots can cover the arc. The box is harder, and requires about 50 shots for there to be no safe zones at all. This gives 20 shots required for a 30% chance of a hit. If the boat has a standing start, then you require considerably less, so you can assume that the boat will not want to slow considerably. This will increase the odds further.

The speed is too high it would be 30 but more like 20. And I'm not seeing where you covered the full arc of possibilities, just one turn to the max and no turning at all for your box, which is highly unrealistic. You have to cover all the possiblities inbetween, though we can maybe put some likely turnings on no more then X degrees port or starboard

Though even for your own numbers your still waaaaayyy overbudget here. You aren't going to get 20 or 50 shots at this. Given the melting problems already known (nice run down of those (http://www.military.com/soldiertech/0,14632,Soldiertech_RailGuns,,00.html)) the earlier 3 shots per ship is highly optimistic. Real world is more like 1 shot per ship at a time for a single volley, engineers only know the cool down to not break it.

Even at 3 per ship welll... you want to get your shots to say below 9 for this to become occaisonally possible or make your ships a hell of a lot cheaper.



Focus fire does not mean out number your opponent. It is simply the obvious response to an enemy's only defense being limited in capacity. Having 10 ships firing at you does not mean that you are alone, simply that they have made a tactical choice to focus on you for this particular salvo.

Yes it does. When you needed it to make your plan work.

And ten ships? The USN is made out of money then?

They only have 84 smallboys, and you want them to travel in groups of 10. I'd spot you up to 100 with an ambitious building program but still you use it up on your carriers. Or not quite depending on what's been commissioned. Current battle groups run around with about half that, or less. You've lost all your indepent deployments and anything that doesn't need a carrier's (still better) projection ability or perhaps worse are wasting your carrier. That's a hideous strategic disadvantage, because you are forced to deploy in force. Especially given how much has to be in port for maintenence at any given time.

And when (not if) you take losses needing focused fire means you drop below a given threshold your strategy falls apart and the back end of the fight swings against you. Remember you will be taking longer range hits from aircraft and missiles before these even come into play. And probably whatever they cook up for drones in the future.

Oh and of course subs too again.

There's just so many layers for why this isn't worth it as more then basic research.

[Cikomyr]

Is it that easy to know the railgun has been shot at you?

Also, doesn't the 10 shots/minute allow for aim correction and make up for the slow evasive manoeuvers of a ship?

[Gnoman]

Is it that easy to know the railgun has been shot at you?



Short answer: No.

Longer answer:
In order to dodge something, you need to find the exact spatial coordinates that it will pass through, and ensure that you do not occupy those coordinates at the same time it does. At short ranges and low speeds, doing so is easy and instinctual. Against something this fast from this far away, you need very precise data and a fast computer to process it. Specifically, you need the exact range and bearing at several distinct points in order to compute the projectile's course. This data must be obtained via sensors of some sort.

There's five major detection systems currently available. These are Infrared, Radar/Lidar (similar enough in this case to be interchangable), Sonar, and Mark One Eyeball. We'll deal with these in reverse order.

Direct visual observation is essentially useless in this case, as the prjectile is simply too fast for the human brain to track and respond to, while visual-range tracking via computer without human assistance is highly problematical. Making matters worse, it is very difficult to get precise range and trajectory information from simple observation.

Sonar is similarly useless. It could probably tell you that the weapon was being fired, depending on the accoustic characteristics of the shot and local water conditions. Gaining any other information is, in a word, impossible.

Radar and Lidar (The former uses radio waves, while the latter uses laser pulses) are probably the only sensor that could be of use in dodging a shot. Odds are extremely slim, however. A twenty-three pound aerodynamic projectile will have an incredibly small "radar cross section", which is a very fancy way of describing the strength of the radar return from an object. Due to the target profile, this will probably be in the same range as large birds, people, or other very tiny targets, meaning that the radar computer would "squelch" it from the display in the unlikely event that they even got a solid return on it in the first place.

Infrared, while probably quite good at actually seeing the shot, as they'd probably be very hot, remains a passive sensor, and the laws of physics make precise ranging information unobtainable from a purely passive source without triangulation, which simply takes far too long to be useful.

In other words, it doesn't matter how much time the projectile flight gives you to dodge, since it is essentially impossible to predict the impact point in the first place. A ship under railgun fire would have to rely on the exact same tactics that ships have been using to avoid ballistic fire for literally centuries, going back to the days when the projectiles in question were ballista bolts and catapult stones. You either change speed and direction at complete random, or you steer opposite of how you think your opponent corrected (A popular method of this was to steer straight for the shell splashes, as that's where they're trying not to hit again.

[Cikomyr]

By the way, I calculated that, at mach 5, it takes about 220 seconds for a projectile to cross 370 kilometers. That's a 3 minute delay between firing and landing. How far/wide can a ship move in that time?

[Gnoman]

If you figure an average speed of 40 knots (most nuclear powered warships are faster than this, but it is fast for non-nukes), then a ship travels 74.08 kilometers in 60 minutes, 7.408 in 6 minutes, and thus around 3.7 km in three minutes.

[Broken Crown]

You can got a reasonable chance to at least mission kill a carrier with any modern warship already. Couple of decent holes in the flight deck and its an amphib until it gets back to port and is repaired. That's assuming of course you can sneak through its defensive screen undetected.

And no the railgun doesn't really help because the combat radius on an F-18 is over 300 nmi and (in theory) the F-35 will be over 500.
Of course, another way to mission-kill a carrier is to shoot down its aircraft. If they come to you, range isn't a big issue. (And speaking of white elephants...)


So if you've nullified the entire airborne theater of battle then yeah your longer range gun will have a purpose because its suddenly WWI again.
Do you suppose that's what they're planning for? Does the navy have such high hopes for its new anti-missile and -aircraft lasers that they're anticipating a return to the Dreadnought Era?


Heck and that's still assuming the carrier doesn't just decide to bug out before you get that close.
If your enemy abandons the theatre of operations to you, then you win. (At least, according to Mahan, though his theories weren't without their problems.)

[Lord Torath]

Sonar is similarly useless. It could probably tell you that the weapon was being fired, depending on the accoustic characteristics of the shot and local water conditions. Gaining any other information is, in a word, impossible.It's actually more useless than that. Sonar information travels at the speed of sound in water (http://www.engineeringtoolbox.com/sound-speed-water-d_598.html), which is under 5000 ft per second at the high end (of ocean temperatures). Which means the sonar signal will arrive just after a Mach-5 projectile.

[Cikomyr]

If you figure an average speed of 40 knots (most nuclear powered warships are faster than this, but it is fast for non-nukes), then a ship travels 74.08 kilometers in 60 minutes, 7.408 in 6 minutes, and thus around 3.7 km in three minutes.

Holy crap, they are much faster than I imagined.

Okay, point taken.

[Karoht]

In regards to the slugs.
I read somewhere that the military plans in implimenting 3D printing systems in some of their newer ships. The reasoning is pretty simple. Lets take the propeller for example. Their storage systems allow them to carry two propellers, if they also want to carry a variety of parts they may also need to service the engine and other critical systems.
Or, they pack a 3D printer and bins of the raw materials, and make whatever parts they need on the fly. This suppliments a much smaller storage of parts. And they can do it in something like 1/3rd the space.
As far as these slugs go, it stands to reason that they too could be produced by such a 3D printing system. So perhaps some of the cost savings come from requiring a smaller and less secure ammo hold, and printing more rounds on demand.

However, as awesome as 3D printing tech is, I can not comment regarding how long it would take to print a single round (given the round complexity, any imperfection could damage the gun) therefore it is difficult to evaluate this trait as advantage or disadvantage. The ability to self-supply if needed is definitely of value, but to what degree? What we do know however, is that the military wants to go more automated as time goes on, this could potentially play a role in that.

I see this as a side bonus rather than a major one. Also, it is unlikely that they will deck out an entire ship in these guns for quite some time. They will probably stick with traditional ammo (current artillery systems + missiles) supplimented by the rail guns for quite a while yet.


EDIT:
I do hate to bring this up, because I dreadfully disenjoy discussing such things, but what about nuclear delivery?
ICBM's have infra red to tell us of a launch, and anti-missile systems can defeat them.
If we scale up the rail guns (possibly to absurd levels, likely not financially feasible) and obviously the size of the round as well, could one potentially fire a round as far as another nation? Across the ocean? Go up over the poles? Or does the (ballistic?) math work that way in reality?

[Cikomyr]

with the basic 360km gun, you could easily shoot over the smaller countries like Moldova. and probably bombard Iran all the way from Saudi Arabia.

[Karoht]

with the basic 360km gun, you could easily shoot over the smaller countries like Moldova. and probably bombard Iran all the way from Saudi Arabia.I suppose. Though Soras mentioned some of the issues involving firing arc and the finesse involved right along side the brute force. It was more of a question of "does physics work this way in practice or just on paper?"

Mind you, accuracy isn't that much of a concern when you are firing a nuke. Maybe. I'm not really up on how sensitive/particular one would have to be with these kinds of forces at play.

[Madcrafter]

In regards to the slugs.
I read somewhere that the military plans in implimenting 3D printing systems in some of their newer ships. The reasoning is pretty simple. Lets take the propeller for example. Their storage systems allow them to carry two propellers, if they also want to carry a variety of parts they may also need to service the engine and other critical systems.
Or, they pack a 3D printer and bins of the raw materials, and make whatever parts they need on the fly. This suppliments a much smaller storage of parts. And they can do it in something like 1/3rd the space.
As far as these slugs go, it stands to reason that they too could be produced by such a 3D printing system. So perhaps some of the cost savings come from requiring a smaller and less secure ammo hold, and printing more rounds on demand.

However, as awesome as 3D printing tech is, I can not comment regarding how long it would take to print a single round (given the round complexity, any imperfection could damage the gun) therefore it is difficult to evaluate this trait as advantage or disadvantage. The ability to self-supply if needed is definitely of value, but to what degree? What we do know however, is that the military wants to go more automated as time goes on, this could potentially play a role in that.

I see this as a side bonus rather than a major one. Also, it is unlikely that they will deck out an entire ship in these guns for quite some time. They will probably stick with traditional ammo (current artillery systems + missiles) supplimented by the rail guns for quite a while yet.


EDIT:
I do hate to bring this up, because I dreadfully disenjoy discussing such things, but what about nuclear delivery?
ICBM's have infra red to tell us of a launch, and anti-missile systems can defeat them.
If we scale up the rail guns (possibly to absurd levels, likely not financially feasible) and obviously the size of the round as well, could one potentially fire a round as far as another nation? Across the ocean? Go up over the poles? Or does the (ballistic?) math work that way in reality? There are a few problems with the 3D printing. While it would work decently for repair parts, it's not something you would use to print ammunition, at least at the current level of technology. While fine for small parts, the large size of the railgun rounds would require a very big and expensive printer. Secondly, one of the big drawbacks of 3D printing is it's slow. I would estimate it would take at the very least half a day to print one round. Finally is the issue of temperatures. Those slugs are designed and made with super high melting metals, probably either tungsten or some kind of nickel alloy, in order to survive being fired at such velocities. The highest temperature 3D printing I know of is about 700-800 degrees C, less than a quarter the melting point of tungsten, so one wouldn't even be able to melt the powder.

And yes, if you built a large enough gun, you could fire it really far. There have been discussions about using giant railguns to fire spaceships into orbit to reduce the need for conventional fuel. But yeah, accuracy will suffer the farther you go, so you probably wouldn't want to use it to fire too far. That's why the ICBMs have guidance systems after all.

[Mando Knight]

EDIT:
I do hate to bring this up, because I dreadfully disenjoy discussing such things, but what about nuclear delivery?
ICBM's have infra red to tell us of a launch, and anti-missile systems can defeat them.

ICBMs, as the "inter-continental" part of the acronym suggests, are designed to travel thousands of kilometers before delivery, giving a sufficiently-equipped defender plenty of time (relatively speaking) to verify the launch, track the missile, and ready the interception system.

A Mach 7 projectile from only 100km or less away is relatively hard to dodge, particularly if you don't have perfect detection... and the US Navy is probably pretty sure that they can limit a theoretical opponent's ability to detect and track a railgun slug.

Finally is the issue of temperatures. Those slugs are designed and made with super high melting metals, probably either tungsten or some kind of nickel alloy, in order to survive being fired at such velocities. The highest temperature 3D printing I know of is about 700-800 degrees C, less than a quarter the melting point of tungsten, so one wouldn't even be able to melt the powder.
Yeah, tungsten or high-temp nickel alloys have the issue of being really hard to melt for 3D printing purposes... the materials that we use for high-temperature moving parts are the materials you're trying to melt. Melting your 3D printer usually doesn't work out so well.

[Karoht]

So the chance of these guns replacing ICBM's as a delivery system for nukes (for the foreseeable future) is low then? Wonderful news.

[ace rooster]

You can got a reasonable chance to at least mission kill a carrier with any modern warship already. Couple of decent holes in the flight deck and its an amphib until it gets back to port and is repaired. That's assuming of course you can sneak through its defensive screen undetected.

And no the railgun doesn't really help because the combat radius on an F-18 is over 300 nmi and (in theory) the F-35 will be over 500. According to wiki anyways. But that's higher then anyone is claiming for the railgun, never mind with enough weight of fire to ensure a hit. You'll need effectively perfect air defense just to handle the sailing just to get in range. So if you've nullified the entire airborne theater of battle then yeah your longer range gun will have a purpose because its suddenly WWI again.

Heck and that's still assuming the carrier doesn't just decide to bug out before you get that close. Though I guess a DDGN/CGN isn't an entirely unreasonable idea here it will have to be one to win that race, which is further costs of course.

...Or...

You can always just do the smart thing and build a submarine to kill a carrier.



The speed is too high it would be 30 but more like 20. And I'm not seeing where you covered the full arc of possibilities, just one turn to the max and no turning at all for your box, which is highly unrealistic. You have to cover all the possiblities inbetween, though we can maybe put some likely turnings on no more then X degrees port or starboard

Though even for your own numbers your still waaaaayyy overbudget here. You aren't going to get 20 or 50 shots at this. Given the melting problems already known (nice run down of those (http://www.military.com/soldiertech/0,14632,Soldiertech_RailGuns,,00.html)) the earlier 3 shots per ship is highly optimistic. Real world is more like 1 shot per ship at a time for a single volley, engineers only know the cool down to not break it.

Even at 3 per ship welll... you want to get your shots to say below 9 for this to become occaisonally possible or make your ships a hell of a lot cheaper.



Yes it does. When you needed it to make your plan work.

And ten ships? The USN is made out of money then?

They only have 84 smallboys, and you want them to travel in groups of 10. I'd spot you up to 100 with an ambitious building program but still you use it up on your carriers. Or not quite depending on what's been commissioned. Current battle groups run around with about half that, or less. You've lost all your indepent deployments and anything that doesn't need a carrier's (still better) projection ability or perhaps worse are wasting your carrier. That's a hideous strategic disadvantage, because you are forced to deploy in force. Especially given how much has to be in port for maintenence at any given time.

And when (not if) you take losses needing focused fire means you drop below a given threshold your strategy falls apart and the back end of the fight swings against you. Remember you will be taking longer range hits from aircraft and missiles before these even come into play. And probably whatever they cook up for drones in the future.

Oh and of course subs too again.

There's just so many layers for why this isn't worth it as more then basic research.

The way I calculated the area to expect where the ship will be located was to try to work out the extreme cases, and apply the fact that the ship must use some maneuver in between. At one extreme, we have the situation where they are not prepared to lose any speed. This limits the rate of turn considerably, hence the arc. A turn of about 60 degrees is about the maximum that can be achieved in the timescale without losing considerable speed, The orientation of a ship on this arc is known, which limits the shots required considerably. By aiming for the rear of the ship at this limiting behavior, you account for situations where the target slows by up to 20% average speed. At the other extreme we have hard turns. These do not happen instantly, And draw a huge amount of kinetic energy from the ship, as well as increasing drag in the water. You will be able to get round 90 degrees in 30 seconds, but you will be basically stopped, still spinning, an about 2 ships lengths in front of where you started the turn. It will not be possible to end up less than a ship length in front of where you started, or more than about one and a half abeam with hard turns. A fast run with a shallow turn can put you further abeam, but then you are on the arc. Hence you are either on a fast run with a constant gentle curve (or near enough that a shot with this assumption will hit you), or you are between 1 and 4 ship lengths in front of your starting point, and up to 1.5 boat lengths abeam, hence the arc and box.

The particular numbers are close to real numbers, but mostly to make the numbers round given this is an estimate anyway. The focus fire thing is required if the enemy can track your shots to the extent that they know where all of your shots are going to land the moment you fire them (more precisely than the person firing the shots), and are at max speed so can maneuver well, and you are going to hit them anyway. If they are actively avoiding shots then focusing is the natural response (2 shots are more than twice as hard to dodge). The size and distribution of fleets will follow the tactics, not the other way round.

The melting thing is a technical challenge, as was landing a plane on a boat reliably in the 30s. Are you asserting that there is no way for this to work reliably? You may be right, but it seems hard to justify. Boffins love a challenge.

No matter what developments occur in aircraft, missiles, and drones, a non nuclear anti ship warhead will always need to be large. I am prepared to make this assertion, so feel free to challenge it with any remote possibility you can find for getting through an unknown ship's defenses with a sub 100kg warhead. This puts a hard upper bound for the capacity of a ship to carry them and the survivability of them no matter the tech. In contrast there is no minimum size for an anti missile system, and improved tech has far fewer limits on improving the effectiveness of such a system. A sufficiently advanced phallax system could concievably down a missile with a single bullet, while a missile with any level of advancement could not destroy a ship with a 1kg (non-nuclear) warhead. Tech will push missile defenses to get better far faster than a missile offense can hope to keep up. If there is a mistake in my logic feel free to point it out.

[Soras Teva Gee]

Of course, another way to mission-kill a carrier is to shoot down its aircraft. If they come to you, range isn't a big issue. (And speaking of white elephants...)

If you have enough missiles and/or aircraft to defeat the business ends carrier battle groups then you've won control of the seas already.

So yeah...



Do you suppose that's what they're planning for? Does the navy have such high hopes for its new anti-missile and -aircraft lasers that they're anticipating a return to the Dreadnought Era?

I never presume the military industrial complex to be playing with a full deck anyways. However what I think is they've visions of shore bombardment role with a secondary in anti-shipping. Not any kind of paradigm shift in naval operations.

And I don't think hitting stationary land targets with a weapon you say can't use in less then dead calm seas because it has a fraction of a degree margin of error... and oh fraction of a degree margin of error period is all that worth the inevitable money.



If your enemy abandons the theatre of operations to you, then you win. (At least, according to Mahan, though his theories weren't without their problems.)

Well yeah except when you say are only at a momentary disadvantage because a nessecary element was out of position, which is about the only way this is going to happen. Then showing the better part of valor is smart and you either lead the opponent on a merry chase away from their objective, or you come back with the initiative this time.



No matter what developments occur in aircraft, missiles, and drones, a non nuclear anti ship warhead will always need to be large. I am prepared to make this assertion, so feel free to challenge it with any remote possibility you can find for getting through an unknown ship's defenses with a sub 100kg warhead. This puts a hard upper bound for the capacity of a ship to carry them and the survivability of them no matter the tech. In contrast there is no minimum size for an anti missile system, and improved tech has far fewer limits on improving the effectiveness of such a system. A sufficiently advanced phallax system could concievably down a missile with a single bullet, while a missile with any level of advancement could not destroy a ship with a 1kg (non-nuclear) warhead. Tech will push missile defenses to get better far faster than a missile offense can hope to keep up. If there is a mistake in my logic feel free to point it out.

And your missile countermeasures will have to be damned close to perfect to close the range gap unless you are going to be attacking with missiles yourself. You want to argue missile strategies that's one thing, but won't help the railgun's case as an alternative. Or you need further improvements on the railgun. Cost efficiency is a big priority, but not if it still can't get the job done because you get shot up beyond your range of response.

Right now this sort of stuff is in its infancy. Best case I'm aware of is Israel's Iron Dome (http://en.wikipedia.org/wiki/File:Iron_Dome_near_Sderot.jpg), but digging into the details it had new missiles against old (like 60s old (http://en.wikipedia.org/wiki/Grad_rocket)) unguided rockets. The idea is sound of course, but far as I know we haven't had the inevitable next step of a missile designed to account for a counter-missile. You will need comparable maneuvering performance in both eventually to hold up, so you may not be able to realize the savings you want/need on defensive missiles. There is INDEED a minimum size on unless you want it too sluggish to get into position.

It a long way from what you'd need to make naval guns viable again.

At a deeper level assumptions about tech advance are just that, assumptions. Its fundamentally and unknowable, because finding out what you don't know may well mean you can't do it after all, the physics just isn't there.

You want to know my personal prediction... you might just have no surface navy worth mentioning at some point in the 21st century. Not a thing under discussion means **** to a submarine. Doesn't even matter about the railgun. Just take my skepticism about nullifying air power, combine with planes strategically refueled in air, spice with stealth tech, season liberally with shore based long range missiles and heck I'm not sure I'm prepared to back anything afloat having good odds.

Its not a prophecy or anything but that's something I think the tech is proverbially already on the shelf to do.

[Gnoman]

I never presume the military industrial complex to be playing with a full deck anyways. However what I think is they've visions of shore bombardment role with a secondary in anti-shipping. Not any kind of paradigm shift in naval operations.

And I don't think hitting stationary land targets with a weapon you say can't use in less then dead calm seas because it has a fraction of a degree margin of error... and oh fraction of a degree margin of error period is all that worth the inevitable money.


Stabilizing a gun is trivial. The level of stabilization needed for long-range is several orders of magnitude less than that already in place for rapid-firing existing cannon, as recoil imparts far, far greater movement into the system than any water conditions short of a heavy storm.





Well yeah except when you say are only at a momentary disadvantage because a nessecary element was out of position, which is about the only way this is going to happen. Then showing the better part of valor is smart and you either lead the opponent on a merry chase away from their objective, or you come back with the initiative this time.



And your missile countermeasures will have to be damned close to perfect to close the range gap unless you are going to be attacking with missiles yourself. You want to argue missile strategies that's one thing, but won't help the railgun's case as an alternative. Or you need further improvements on the railgun. Cost efficiency is a big priority, but not if it still can't get the job done because you get shot up beyond your range of response.

Right now this sort of stuff is in its infancy. Best case I'm aware of is Israel's Iron Dome (http://en.wikipedia.org/wiki/File:Iron_Dome_near_Sderot.jpg), but digging into the details it had new missiles against old (like 60s old (http://en.wikipedia.org/wiki/Grad_rocket)) unguided rockets. The idea is sound of course, but far as I know we haven't had the inevitable next step of a missile designed to account for a counter-missile. You will need comparable maneuvering performance in both eventually to hold up, so you may not be able to realize the savings you want/need on defensive missiles. There is INDEED a minimum size on unless you want it too sluggish to get into position.


Even without an effective laser system, it would take huge numbers of missiles to score hits on a modern naval formation. Aircraft can intercept bombers carrying air-launched weapons while they're still vastly out of range, the ships themselves carry SAMs that are quite effective at killing the missiles themselves, and a combination of decoys, jamming, and point-defense autocannon will greatly attrit any leakers. This isn't mere theory or based purely on simulations, either. While the integrated system hasn't been tried against an all-up missile assault, all of the components have been combat-proven, some againts far more difficult threats. (Naval SAMs, for example, have successfully destroyed SRBMs and falling satellites, both orders of magnitude more difficult targets.) Of course, this system is heavily ammunition dependent, can only engage a certain number of targets simultaneously, and all of the systems involve take a considerable amount of time to reach their targets, making follow-on targeting difficult. Not to mention that you're throwing millions of dollars worth of munitions away in this one engagement. Now, consider a system that has no ammuniton, engages targets instantly at any possible range, has virtually all expenses in the unit itself (meaning a high up-front cost, but very little to actually operate), and does not have a maximum target limit.

That's why lasers are such a critical defensive paradigm shift. A lower powered laser will burn out all guidance and fusing systems on any missile, while a more powerful one will simply destroy it. This takes approximately a millisecond unless the target is heavily armored (which would make them nothing more than skeet for conventional anti-missile systems), and have effectively no ammunition limitations. In short, replacing an AEGIS-type missile cruiser with a laser ship means that, instead of confidently being able to stop sixty or seventy missiles/aircraft , you now have the ability to stop hundreds, at effectively zero cost. If defensive lasers are put into service at 1% of their theoretical efficiency, every combat aircraft and missile on the planet instantly becomes as obsolete as the musket.



You want to know my personal prediction... you might just have no surface navy worth mentioning at some point in the 21st century. Not a thing under discussion means **** to a submarine. Doesn't even matter about the railgun. Just take my skepticism about nullifying air power, combine with planes strategically refueled in air, spice with stealth tech, season liberally with shore based long range missiles and heck I'm not sure I'm prepared to back anything afloat having good odds.

Its not a prophecy or anything but that's something I think the tech is proverbially already on the shelf to do.

Funny thing is that every single one of those elements has been in place since the 60s without obsoleting the surface ship. Submarines are too slow (in wartime, moving at more than 25-30 knots is a very expensive form of suicide, as a sub that is heard will very shortly become a target) and too limited in what they can do (they are quite good at engaging other subs, and aren't bad at taking out surface ships (although modern ASW doctrine is extremely effective, and they can launch small numbers of cruise missiles (except for the Ohio SSGN conversion, most subs carry 12 at most) at ground targets. THis is the complete limit of their combat ability). Mid-flight refueling would require one tanker for every ten or twelve aircraft in a strike (which would rapidly become prohibitively expensive), and pulling back to your nearest controlled land mass would eliminate your ability to respond to tactical threats with any sort of speed compared to what is currently provided by naval aviation. Heavy deployement of shore-based missiles would require clusters a couple of hundred missile launchers (given the already-existing levels of missile defense obtainable) situated roughly every fifty miles along your coastline (meaning, for example, that the US would require 200 such installations), and would only give you control of the seas within about a hundred miles, when a single carrier + escorts would cost a tenth as much and be able to intercept a threat much further away.

[Yora]

How would a railgun compare to the autocanons currently mounted on most warships against small vessels nearby? I would assume the current prototypes are the size they are now, because it's easy to work on. Once you got it worked out, scaling it down to smaller sizes and powers shouldn't be too hard.
Would it be worth the investment? Autocanon shells are basically just very large bullets, those shouldn't be too expensive and not used a lot anyway, so it might not be worth the effort to replace them with railguns.

[Mando Knight]

How would a railgun compare to the autocanons currently mounted on most warships against small vessels nearby? I would assume the current prototypes are the size they are now, because it's easy to work on. Once you got it worked out, scaling it down to smaller sizes and powers shouldn't be too hard.
Would it be worth the investment? Autocanon shells are basically just very large bullets, those shouldn't be too expensive and not used a lot anyway, so it might not be worth the effort to replace them with railguns.

The US Navy seems to think it's at least worth testing. The railgun slug travels several times faster and quite a bit farther than any conventionally-propelled cannon shell.

[Hecuba]

How would a railgun compare to the autocanons currently mounted on most warships against small vessels nearby? I would assume the current prototypes are the size they are now, because it's easy to work on. Once you got it worked out, scaling it down to smaller sizes and powers shouldn't be too hard.
Would it be worth the investment? Autocanon shells are basically just very large bullets, those shouldn't be too expensive and not used a lot anyway, so it might not be worth the effort to replace them with railguns.

Ultimately, a rail gun just shoots large bullets too. It just happens to shoot them much faster and much further.

Generally, if you're dealing with small close targets, the benefits of a railgun will be significantly diminished:

It's (definitionally) close, so the range benefit is a non-factor.
Any materials savings when compared to other purely ballistic projectiles would be more than offset by the increased costs of engineering the projectile precisely enough for the much higher velocity.


The only case where there would be significant benefit would be situations when additional the destructive power delivered by the higher velocity would be necessary.

I suppose if it is really urgent that a small nearby ship become shrapnel rather than simply being disabled or sinking, the railgun might be your tool of choice.

In general though, it's benefit comes primarily from its increased range: the Navy's claiming a 100+ mile range.

[Mando Knight]

3. Harder to defend against. Railgun rounds are smaller and travel faster than missiles and so are harder to intercept.

They also lack on-board guidance systems, which against advanced militaries can be as much a benefit as a drawback, depending on their ECM.

[Cikomyr]

The fact that every rounds don't carry explosives in any measure probably will make their transportation a much, much simpler affair.