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The US Navy Wants More Railguns and Lasers, Less Gunpowder
coondoggie writes Speaking before nearly 3,000 attendees at the Naval Future Force Science and Technology EXPO in Washington, D.C., Chief of Naval Operations Admiral Jonathan Greenert charged his audience to reduce reliance on gunpowder in a wide-ranging speech on the future technological needs of the Navy. "Number one, you've got to get us off gunpowder," said Greenert, noting that Office of Naval Research-supported weapon programs like Laser Weapon System (LaWS) and the electromagnetic railgun are vital to the future force. “Probably the biggest vulnerability of a ship is its magazine—because that’s where all the explosives are." Weapons like LaWS have a virtually unlimited magazine, only constrained by power and cooling capabilities aboard the vessel carrying them. In addition, Greenert noted the added safety for Sailors and Marines that will come from reducing dependency on gunpowder-based munitions.
They are not eliminating all "gunpowder". They may be able to eliminate the propellant used to launch projectiles but many of those projectiles will still have explosive warheads. Its an improvement, but there will still be armored magazines for such projectiles.
I am figuring your comment is in jest.
A laser powerful enough to bring down an airplane would burn thru a mist and probably melt a mirror instantly before the can use a reflection to aim it back.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
There's actually a few tradeoffs here. Unless it's a nuclear powered ship, then efficiency does matter. Fuel is much more energy dense, due to not having its own oxidiser, but railguns are fearfully inefficient. Unless they get the efficiency up then the fuel might take up more space. That said, being liquid, it fits into awkward spaces more easily.
As for power, that's an interesting one. If you look at the proposed railgun specs, the slugs have about the same kinetic energy as a WWII battleship round from at 16" gun. While the velocity of a railgun round is much higher, it doesn't weigh well over a ton. Plus, the battleship round also has about the same energy again as an explosive payload. So in practice the railgun will have about half the energy delivery capacity of a single round from a WWII battleship.
Of course, the railgun has a much longer range, a much higher speed, is much smaller and doesn't requite an unstable mix of fuel and oxidiser to be carried so that is a win.
In terms of armor, that's more or less gone from ships. The reason being that modern torpedos and some missiles which dive shortly before impact essentially make explode under the ship not against it, lifting it partly out of the water and creating a bubble which the ship falls into breaking its back. Armor is more or less worthless against that sort of attack. So if you're in a war with the USSR, there's no point in having any.
Excpet the only naval engagements from western nations in vaguely recent times have been things like the exocet missile strikes frmo the Falklands war (again less energy than a battleship round, and armor would have helped), a boat packed with explosives (again armor would have helped) and a few others. So ship armor is already more or less worthless against a modern well equipped navy, but it's probably worth having for when one isn't engaging one of those.
But back to the railgun.
There's an interesting thing that hitting a target with a high energy inert round often doesn't do a whole lot of damage. There was a case in WWII of some armed merchant cruisers (i.e. cargo ships with a couple of obsolete guns welded on) were mistaken for cruisers by some German raiders. The raiders engaged at long range with AP rounds and scored some direct hits. The AP rounds went all the way through the unarmored ships and out the other side without detonating (they were designed to penetrate a bit into armor and then detonate: the lack of armor caused the warhead to not trigger). The end result was that the ships wound up with some perfectly survivable 15" holes in them and managed to escape.
Likewise, the British army still like their HESH rounds, because the APFDS rounds (basically a long, thin very high speed slug designed to penetrate thick tank armour) have the annoying habit of going right through more lightly armoured vehicles without doing significant damage except for two small holes, where as the HESH rounds tear them open.
The cause of this is that very high energy rounds are hard to stop. Even the target has trouble stopping them, and if it fails to, then they leave with most of their energy and deliver it elsewhere.
In fact come to think of it, back when muskets were becoming obsolete, some armies found that although the modern high speed, high accuracy bullets made it much easier to hit the target, they tended to go right through people. The result being that again, the round not only had to hit a person but unlike a musket ball, had to hit something important, so there was a much higher survivability rate from people who were shot.
So, what I wonder is how the railguns fit into this. It seems that they'd be prone to very effectively making a couple of small holes in whatever they hit and delivering most of the energy into the sea or ground. Unless you actually hit the engines or some other critical piece, a ship, especially a warship can survive a surprisingly large number of holes before it is put out of action.
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Erm? Care to explain how a railgun would cause an EMP?
Because there is a huge electromagnetic discharge?
It's kinda how railguns work.
Admit nothing. Deny Everything. Make Counter-accusations.
I am sure he actually understood. He just wanted to take the chance to make an idiotic comment about the U.S. to what he hoped would be a receptive audience. I mean it takes a truly special person not to notice just how much the U.S. engages with all the other nations of the world.
What plane has 11 inches of steel?
Ships are killed by planes and subs, by missiles and torpedoes. Big ship to big ship combat just doesn't happen much anymore. Missiles take care of that.
Ships can launch surface to surface missiles and torpedoes as well. Ships are still perfectly capable of killing other ships. They just don't line up and broadside each other with 15 inchers anymore.
The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
Why don't you read what a railgun is and how EMPs are generated?
And EMP is generated by having a very high electrical current somewhere. The better that current couples to the far field, the faster that current happens, and the larger the current is all contribute to the magnitude of the EMP. Railguns involve a very larger current, and require it to be applied over a loop with some amount of area to it, so it covers the first and third point well, and just only partially covers the speed one because they are kind of slow compared to other high current devices.
I've worked with small railguns before on plasma experiments. While pulsed plasma experiments already create EMI nightmares if you make any mistake in shielding or groundloops, the railgun has destroyed electronics in diagnostics near by that needed to be rebuilt and better designed. While not on the spatial scale of an EMP by a nuclear bomb (or even a well designed Marx generator...) it does require hardening and careful design of electronics in the vicinity. A lot of military equipment is already hardened anyway, but just making parts of a railgun functional and surviving itself already go a long ways there anyway.
Not that there is that much sensitive electronics needed to make it work, most of it is simple, robust high power electronics, and the sensitive stuff is just there to report on its performance. I don't know what types of switches, etc., they use on the large scale railguns, but if they use things like ignitrons, the basic parts of the railgun will be large capacitors and vacuum electronics, which are very robust against voltage spikes unlike silicon stuff.
A rail gun works by creating a massive magnetic field with a huge current. That same current induces massive Lorenz forces. Those Lorenz forces accelerate the projectile.
To accelerate effectively the current ramp needs to be steep.
That combination of a massive magnetic field with steep ramps is an ElectroMagnetic Pulse, or EMP.
The railguns the Navy develops are big and thus they have big electromagnetic pulses. Any not EMP hardened electronics near them just die.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
Plasma is opaque.
What do you mean plasma is opaque? As long as the electromagnetic wave is above the cut-off, higher than the plasma frequency which depends on density for colder plasmas, then electromagnetic wave will propagate through plasma. Plasma at the same density as air is still has a cutoff in IR above the wavelength of something like a Nd:YAG laser.
But regardless, still depends on the situation, because for pulsed lasers, the time scale of energy absorption is way faster than the timescale that ablated material can move away from the surface being hit. Even without using pulsed lasers, the intended targets are fast moving airborne targets, where there would be no accumulation of plasma or obstructions in the air in front of what is being hit anyway.
And any ambient scatter (and there will be a lot) will be enough to cause permanent blindness for very long distances in all directions
Diffuse scatter of a 1 MW laser would be safe at a distance on the order of 100 m. Even with a much larger safety factor, and disregarding that specular reflections would happen on a much shorter timescale with higher safe power density limits, there is usually not much that close to an aircraft or missile, especially one being shot at.
so you run the risk of having your weapon classified as prohibited under the rules of warfare.
That laws are poorly written in the sense that a weapon that is not intended for such uses is ok, even if they do happen to cause the same effects. If the laser is not intended for blinding and is not used for the purpose of blinding, it doesn't matter if someone gets blinded in the process. A lot of weapons intended for use on equipment only ends up hurting personnel anyway...
Currently railguns have about the same muzzle velocity as a WW2 battleship cannon. ... There might be some exceptions. I think some of the giant land guns might have had higher muzzle velocities.
WW2 battleship "cannon" (actually "guns" as they had rifling), up to 18" bore, were the longest range conventional guns ever, although the accuracy deteriorated beyond about 20 miles. Anti-aircraft guns had a higher muzzle velocity, but being smaller bore did not have such range (air resistance had greater influence). There have been higher velocity and greater range unconventional guns such as with additional firing chambers up the barrel, and the experimental German WW2 "Arrow gun" which fired a long thin shell with tail fins out of a larger bore barrel by means of a segmented wooden jacket (a "sabot") which fell away after leaving the barrel.
The germans had a big gun they used against the French and I think there was another one built in the middle east somewhere but it escapes me. Regardless, the weapons were too large to really be practical. They were big white elephants that accomplished very little compared to their cost.
In their day they were not white elephants. The Western Front in WW1 was static so those big guns, usually railway mounted (not to be confused with "rail guns"!), were useful for hitting things like enemy railway junctions miles behind the front, even though it took days to set one up and about an hour to fire each shot. A specially modified one was even used to hit Paris 70 miles away, more as a terror weapon because its shells dropped with no warning from the stratosphere like a modern ICBM. In WW2 two were used very effectively to hammer the Americans at the Anzio landings. The Germans also had massive seige guns which went for explosive power rather than range such as the "Big Berthas" of WW1, technically howitzers, which were very effective at destroying fortifications at short-ish range such as at Liege in 1914.
but railguns are fearfully inefficient.
Compared to chemical propellants? I don't think so.
Unless they get the efficiency up then the fuel might take up more space. That said, being liquid,
I'm fairly certain the nuclear reactor that powers the guns and the ship won't be that big of a problem. They don't do it on diesel.
Armor is more or less worthless against that sort of attack.
Thats why the strengthen the keel ... 40 years ago.
I'd keep going, but I'm just blown away by how you got to +5 on this. You don't seem to know anything at all about you're talking about. You're mixing and matching things in ways that makes them all simply completely false statements.
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Except if the other ship has lasers...
When did the US Navy last fight a proper ship vs ship battle with big guns? This is just a solution in search of a problem/budget .
The most recent US ship-to-ship battle was in 1988 against the Iranians. That's only 26 years ago.
Details from the 'pedia: http://en.wikipedia.org/wiki/Operation_Praying_Mantis
However, the whole point is to STAY ahead of the other naval powers. Most every country today has helicopters, submarines, battle tanks, etc. The pertinent detail here is that the quality of the US's arsenal is often a generation (and sometimes quite a bit more!) ahead of its opponents. This is a major reason as to why the US has lost so comparatively few soldiers in combat since Viet Nam. Being able to dominate the battlefield by technology has been necessary since Og used a rock against Mog instead of a his bare hands, and history is full of examples of countries that didn't keep up with the curve. This is just another wrung on the never-ending technology ladder.
Currently railguns have about the same muzzle velocity as a WW2 battleship cannon
Not even close to true.
The typical muzzle velocity of a typical 16 or 18in gun was around 2500 ft/s.
The Navy's railgun has already surpassed Mach 6, or >6600 ft/s.
No, the railguns the Navy is developing are quite definitely hypersonic and have been for some time.
Not "at some point the in future", but right now.
The guy who said the election was rigged won the presidency with the second-most votes.