Why is the rail gun an interesting weapon?

[mikeph]

The problem with a direct fire gun is that you need to first find the target, and secondly close into range. You might think you know where a carrier is, but let's say it shoots down anything approaching within the 200 miles given (those F-18s are onboard for a reason). How then do you know where to shoot the gun?

Range should be easy to calibrate, then use live satellite images + computer algorithm to calculate the direction, with curvature and Coriolis effects. Fire a test and then make corrections like you would with a mortar. One ship + a UAV all that's needed? Or even a submarine (firing from the surface)?If the ammo is literally just a block of metal, it would seem to be relatively cheap to fire multiple rounds, and, imagine if you're on the ship. You see a block of metal whizz past you. What can you do? You have no countermeasure and you have no way of knowing where the firing position even is.

 

[Drakkith]

Range should be easy to calibrate, then use live satellite images + computer algorithm to calculate the direction, with curvature and Coriolis effects. Fire a test and then make corrections like you would with a mortar. One ship + a UAV all that's needed? Or even a submarine (firing from the surface)?

That's not quite how it works. Satellite images require that a satellite be overhead. Given the very limited number of satellites thanks to their cost, and the fact that their orbits quickly move them out of view of the battlefield, it is extremely unlikely that any country could use them to actively track fleet movements in real time with enough accuracy to bombard them from hundreds of miles out.

Also, your rounds takes entire minutes to arrive, and as soon as the fleet knows they are under attack, if they didn't already, they've started course corrections.

 

[mikeph]

Point 1 I realized, that's why I added a UAV in there.

If "course corrections" is the only countermeasure then I wouldn't want to be on board one of those ships. Cost v cost, the weapon is significantly cheaper than the target, and if striking a ship is a game of chance, the odds can be significantly reduced by firing multiple shots or having multiple weapons.

 

[Drakkith]

Point 1 I realized, that's why I added a UAV in there.

You want to get a UAV near enough to track a carrier group without it being destroyed? Good luck. You're going to need it.

If "course corrections" is the only countermeasure then I wouldn't want to be on board one of those ships. Cost v cost, the weapon is significantly cheaper than the target, and if striking a ship is a game of chance, the odds can be significantly reduced by firing multiple shots or having multiple weapons.

It's not the only one. A flight of F-18's and cruise missiles taking out your Railguns is one hell of a countermeasure in itself. Plus your argument assumes you can even track the fleet well enough to target them effectively. That's going to be a little difficult to do when the carrier group is hell bent on making sure that never happens.

Perhaps people don't understand, but there's a very good reason we went away from direct fire, unguided weapons like cannon fire. Railguns may be more powerful, but they still have severe limitations that must be worked around.

 

[nsaspook]

That's not quite how it works. Satellite images require that a satellite be overhead. Given the very limited number of satellites thanks to their cost, and the fact that their orbits quickly move them out of view of the battlefield, it is extremely unlikely that any country could use them to actively track fleet movements in real time with enough accuracy to bombard them from hundreds of miles out.

So true, It's not like the movies where you can get a Hi-DEF real-time video over a wide area. The oceans are almost impossible to cover with the detail needed to quickly locate a random ship or even a fleet let along provide visual targeting for a gun. RF emissions can be detected with ELINT systems on the surface and/or in space and can triangulate a close position target lock using sophisticated DTOA (Time Difference Of Arrival) techniques (reverse GPS). We would normally go into strict EMCON to evade detection (cold war games with the USSR) and use signalmen or 'other' methods to send messages between ships.http://en.wikipedia.org/wiki/Multilateration
http://www.globalsecurity.org/military/library/policy/navy/nrtc/14226_ch3.pdf

 

[mrspeedybob]

I've seen a couple post about the idea of guided rail-gun projectiles. A quick back-of-the-envelope calculation shows that the acceleration required to go from 0 to Mach 8 in any reasonable distance is quite large. For a 30 meter long gun I got over 12000 G. Is it actually feasible to build a guidance system that can withstand that amount of acceleration. Besides the mechanical acceleration there is the intense magnetic pulse that does the accelerating. Can the necessary electronics be shielded from such a pulse?

 

[d3mm]

He's talking about ICBM's. The missile itself never gets near its target, only the small reentry vehicle that holds the warhead. And it is small, just a bit larger than a person. Currently there is only two anti-ICBM system in the world. The Russian A35 ABM, which uses another nuke to destroy the target nukes, and the U.S. Ground-Based Midcourse Defense (GMD), which uses a kinetic projectile (a high speed missile) to hit an ICBM. (I assume before it launches its warheads)

More than two.

http://en.wikipedia.org/wiki/Aegis_Ballistic_Missile_Defense_System

"Aegis BMD (also known as Sea-Based Midcourse) is designed to intercept ballistic missiles post-boost phase and prior to reentry."

At least one of those ships is parked somewhere off the Korean peninsular right now.

China? Korea? Russia? Missiles aren't that expensive for a modern military.

Assuming you do not mean ballistic missiles, US carrier defence doctrine was developed during the height of the cold war when the Russians had many squadrons of Backfire bombers. They don't have so many now and the carriers have even more missiles. It's not impossible to saturate a carrier group's air defence but you're going need a lot of stuff. That means a major shooting war between superpowers and that means you're not talking about a single carrier.

If the ammo is literally just a block of metal, it would seem to be relatively cheap to fire multiple rounds, and, imagine if you're on the ship. You see a block of metal whizz past you. What can you do? You have no countermeasure and you have no way of knowing where the firing position even is.

Sure, but you'd need to to know where the target was and get a launch platform into range. It'll probably work if you can do that. Your main problem is getting the shot, not what weapon you use. BTW you can actually track a purely ballistic projectile back to its source with radar. They have a man-portable gadgets that can do it now. "shoot and scoot" time is pretty important for artillery.

 

[d3mm]

Because we don't protect the ships with steel anymore protecting them with advanced technology like DEW or rail-guns is necessary to keep up. The BB-62 class ships main use during it's last war was for big gun shore bombardment and cruise missile attacks. You can data link to a UAV or another ship with working sensors for the guns and any (vertical launching system) VLS missiles would still be able to be used.

About the only period anti-modern missile that could stop one cold was the nuke option on this. (It was designed to take out our carriers, very nasty saturation attack mode)

I agree that today there probably isn't an ASM that will penetrate the belt or the deck.

I think you don't realize how electronic a modern conflict is, that a missile may airburst over the top of the ship rather than strike the deck, and that without sensors you've essentially got an armored ammo carrier. How to justify the expense of the ship where a missile cruiser would be more useful in such a situation as it means fewer ships get hit.

Modern ships do have armor, but not steel belt. It's true that a battleship has steel as that's what it was built with, but you appeared to be asking for more steel today. Why you would want steel?. The infantry are wearing ceramic and no-one knows what Secret Sauce is in the frontal armor of a tank. If it worked, you know they would put it on.

If I was sitting 20 miles off-shore, I might want a battleship but I'd be worried about submarines, mines and stupid numbers of shore-based weapons. I'd just get a tiny carrier and station it 200 miles out. If had to be there I'd want patrol boats.

Keeping the engineering spaces intact is the top priority. The USS Stark topside sensors/missiles survived but suffered massive engineering casualties because the warhead is designed to direct the blast after penetration.

Well that is true in the long term. In the short term any warship that loses without combat capability will likely be withdrawn or become a liability.

I should say Stark was a pre-Falklands design. That particular conflict greatly changed western naval doctrine and ship design. It was the first and only large scale combined arms modern naval fight, and before it no-one really knew what to expect or what to build.

There is no way a RPG class weapon can 'defeat' battleship armor if defeat means more than a pin-prick.

Tandem charge weapons can throw a bomb down the hole the first charge makes.

Today, I doubt anyone has a conventional ASM warhead that will penetrate a battleship's armor belt, but if battleships appear, you can bet people will think about making 'em, then none of that steel armor will be worth anything since it's plain steel and not the secret stuff a tank has.

 

[nsaspook]

I agree that today there probably isn't an ASM that will penetrate the belt or the deck.

I think you don't realize how electronic a modern conflict is, that a missile may airburst over the top of the ship rather than strike the deck, and that without sensors you've essentially got an armored ammo carrier. How to justify the expense of the ship where a missile cruiser would be more useful in such a situation as it means fewer ships get hit.

I know how electronic war is today and how full scale naval warfare today means long range standoff weapons so you can survive just long enough to fire back once before you are dead. Most of the 1980's war games had the pacific fleet lasting about 1 day during a full scale attack.https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/a-cold-war-conundrum/source.htm#HEADING1-06

 

[godscountry]

This video is from 2007 but it stated the goal at that time was a 64 mega-joule weapon? I understand the advantages of extended range but it seems like a huge, awkward, and expensive weapon to deliver a relatively small amount of energy. 64 mega-joules is the equivalent of only 14 kg of TNT. Aren't there already much more efficient ways of delivering that amount of destructive energy to a target?

Eventually you will be able to dial in the power to hit and take out a target,all without explosives.The velocity of the projectile is so high it just knocks the turret right off the tank.The better uses of this technology is the ability to launch small satellites without expensive rockets.The Navy has implemented electric catapults on its next generation aircraft carriers and most likely will retrofit all existing steam catapults as time goes on.

 

[cjl]

The Navy has implemented electric catapults on its next generation aircraft carriers and most likely will retrofit all existing steam catapults as time goes on.

Retrofitting wouldn't really be possible - current gen aircraft carriers don't make nearly enough electricity to run an all electric catapult system, and it would involve a pretty extensive redesign to make it possible. I believe the plan is just to replace the current carriers with the new ones (Ford class), rather than trying to retrofit the Nimitz class carriers with a ton of new tech.

 

[brenan]

As we speak (or read) the US navy is trialing their latest ship borne laser system that operates
a 100Kw laser. I'm curious because I was under the impression that an effective weapon of this type
needs to be at least 2 orders of magnitude more powerful. Does anyone know what sort of
distances they are likely to be able to effectively use this against anything worth the cost of an
entire ship (The publicity claim is that this is now a viable device albeit an early development version)
Assuming good weather I'm guessing they'd need to hold precise targetting over a fairly reasonable period?
(far too long for example to destroy a carrier buster)

 

[d3mm]

I know how electronic war is today and how full scale naval warfare today means long range standoff weapons so you can survive just long enough to fire back once before you are dead. Most of the 1980's war games had the pacific fleet lasting about 1 day during a full scale attack.

https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/a-cold-war-conundrum/source.htm#HEADING1-06

Answers allegations of being out of date by linking 30 year old document. ;-)

Some of the principles are the same but the technology has so far advanced since those days. 30 year old computers? Yes, some of the same platforms are in service (F-18 jet) but they have been upgraded so many times, they no longer resemble their original ancestors.

 

[nsaspook]

Answers allegations of being out of date by linking 30 year old document. ;-)

Some of the principles are the same but the technology has so far advanced since those days. 30 year old computers? Yes, some of the same platforms are in service (F-18 jet) but they have been upgraded so many times, they no longer resemble their original ancestors.

The opponents systems have also advanced 30 years, so the only thing that has changed is how fast we can wipe each other out. In one day of all-out non-nuclear naval warfare with a Chinese or Russian Navy we would still be throwing rocks and spears at each other from the burned out hull of a stealth ship because while our electronics are very good, active Electronic Protection (EP) systems will always have effective countermeasures when the system has be almost perfect to stop a debilitating blow from a single large weapon from a incoming cluster of large dumb weapons that are cheap to make. Passive countermeasures (armor, redundancy) are not sexy but are effective in a real shooting war after the first salvo is fired.

 

[Alexi-dono]

Would it be possible/practical to start the projectile with explosives (maybe a shaped charge), and then continue the acceleration with the "rails"?

 

[Drakkith]

Would it be possible/practical to start the projectile with explosives (maybe a shaped charge), and then continue the acceleration with the "rails"?

I wouldn't have believed it, but yes. From here: http://en.wikipedia.org/wiki/Railgun

In some hypervelocity research projects, projectiles are "pre-injected" into railguns, to avoid the need for a standing start, and both two-stage light-gas guns and conventional powder guns have been used for this role.

 

[Alexi-dono]

I wonder if multiple explosions could be used, and if they could be done in a way to give spin to the projectile (rifling). Maybe if they get crazy enough they could combine railguns and nuclear blasts. Example: have a long vertical/semi-vertical tunnel going underground, then have the nuke at the very bottom, and the railgun built into the wall... Though the projectile would have to have a very high heat resistance, as for shape; use a conical shaped charge design. If you really want to go the extra mile; find a way to create a concentrated beam of radiation, that would heat the atmosphere inline with the ballistic flight path for temporary dispersion. (create a partial vacuum for the projectile to fly in).

~just a thought