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World's Most Powerful Rail Gun Delivered to US Navy
An anonymous reader writes "The world's most powerful functional rail gun capable of accelerating projectiles up to Mach 8 has been delivered to the Navy. The new rail gun is a 32-megajoule Electro-Magnetic Laboratory Rail Gun. The Navy eventually hopes to have 64-megajoule ship mounted rail guns. 'The lab version doesn't look particularly menacing -- more like a long, belt-fed airport screening device than like a futuristic cannon -- but the system will fire rounds at up to Mach 8, drawing on tremendous amounts of electricity to generate the current for each test shot. That, of course, is the problem with rail guns: Like lasers, they're out of step with modern-day generators and capacitors. Eight and 9-megajoule rail guns have been fired before, but providing 3 million amps of power per shot has been a limitation.'"
There is no such thing as overkill. There is only "still firing" and "out of ammo."
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A stately pleasure dome decree
The majority of people here seem to think the rail gun is powered by a huge capacitor bank which takes a long time to charge, or required a nuclear power station to run it in a ship....bollocks.
A Megajoule class railgun is powered by a Compulsator, a type of modified alternator ( compensated for low inductance to provide enormous current pulses )...the rotor is spun up by a large engine, and the rotational energy in the rotor is turned into multiple high current pulses...in earlier test systems ( still megajoule class ), they can fire a burst of 10 shots on one spinup. These things can be scaled to fit in a modern tank, or up to naval gun size.
Ampere is a measure of current, not power.
To put it this way, the European Spallation Source is a planned particle accelerator which is planned to have a proton-beam current in the range of a few milli-ampere. That is, comparable to the current drawn by your LCD monitor in standby. The catch is that ESS will be using proton energies up to a billion electron volts, thus making the power output of the accelerator comparable to a small nuclear reactor.
You can NOT quote power in terms of ampere without specifying the voltage. Conversely I've generated several thousands of volts using my bare hands and a piece of nylon, but because the current was rather small nobody noticed.
What is even more interesting is the time over which you can sustain a given power output. Over at our physics department we have lasers with power outputs beyond all the worlds nuclear reactors taken together. The pulse doesn't last very long however...
Surprised more people haven't commented on this. Ending a summary with "3 million amps of power" is a classic Slashdotism. It would once have provoked many responses pointing out that an amp of power makes as much sense as a gallon of distance. Perhaps we can't be bothered correcting the editors any more.
>north
You're an immobile computer, remember?
Meh. He's got some cute pictures, but his grasp of military history is teh fail. The French did *not* discount the possibility of the Germans coming through the neutral Low Countries; in fact, they expected it--it was what they'd done last time, after all. That's what did them in. All their decent units were all lined up on the Belgian border and rushed into the Flanders plain to meet the expected oncoming Germans as soon as Belgium was invaded. But the Germans broke through at the pivot point, in the Ardennes, getting behind the Allied forces now in Belgium and then driving west to the sea to bottle them all up quite nicely, including the British (who managed to evacuate out of the pocket from Dunkirk).
It's interesting how the cost accounting of the modern navy works out. Nuclear power makes sense for carriers and the three classes of subs we operate, SSN, SSBN, and SSGN, but it's never really taken off for surface ships. The last non-carrier nuclear surface boat was the Long Beach, I believe, an escort cruiser.
The whole naming and classification of surface vessels is also weird. Frigate is a name held over from the age of sail. Back then, heavy fighting was done with ships of the line, frigates were used for the free-wheeling missions of escort and raiding and scouting and what have you. Line ships were too important to risk being lost on mundane missions like that. Destroyers were originally called torpedo boat destroyers, ships capable of keeping up with the fleet while screening against torpedo boat attack. A cruiser was not a class but a job description, with frigates operating as cruisers in the age of sail.
By WWII, you had frigates, destroyers, and destroyer escorts operating as small ships working in various roles. Destroyers carried torpedoes to threaten larger ships, 5 inch guns to use against other destroyers and merchantmen, AAA for use against planes and depth charges for subs. The cruiser was intended to be a heavy combatant that could catch anything it could sink and flee from anything that could sink it. You then ended up with all the weird categories of light and heavy cruisers, battle-cruisers, etc. Then you had your battleships, slow sluggers that could not control the range of the fight. Then improvement in propulsion technology created fast battleships that could keep up with the cruisers. Carriers then pissed in everyone's cheerios because the battleship admirals didn't know what to do with them. Concerted air attack could take out a battleship with minimal loss of air crews but the formations the Americans put together towards the end of the Pacific war would have made conventional air attack suicidal for a well-trained and well-provisioned air force, let alone the Japanese. If two US-style fleets faced off, they'd likely run out of planes and pilots before running out of ships, thus forcing the engagement into a gun battle. The rapid development of technology changes everything.
Since the Cold War, the US has dicked around with cruisers and battleships but now the only large surface combatants left are carriers. Even the Aegis cruisers are running on hulls more comparable to destroyers and the arleigh burkes are using the same aegis. With the hitting power of modern anti-ship missiles, it's seen as impossible to armor a ship sufficiently to survive a strike. Then again, US naval thinking is still shaped by the Cold War and the idea that incoming weapons are going to be nuclear so you have to knock them down or else be incinerated, there's no such thing as armoring against a nuke fireball. Since we haven't had a proper naval engagement since WWII, all we're operating under is a bunch of theory that has not been put to the test in a very long time.
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This Mahdi took Shaddam's Throne
The Railguns serve a purpose which right now is being filled by EXTREMELY expensive weapons. The cruise missile has a range of about 600 miles, it also moves at a speed that makes them very easy to shoot down. To compensate for this they fly them at extremely low elevation, but they can still be shot down and you can hear them approaching for quite a while before they get there, making it much easier to avoid being hit by one.
The railgun on the other hand currently has a range roughly 1/3rd the distance of a cruise missile and IIRC the 64MJ version has a range around 2/3 the range of a cruise missile. Not only that but the projectile cannot be shot down as no weapon could catch it, nor even if they could (fired head on) would the interceptor be able to stop it as the kinetic energy of the blob of metal would simply disintegrate anything that tried to stop it with almost no deflection of the weapon. Not only that but the railgun offers extremely high energy on impact, far in excess of the 500-2000lb bomb on cruise missiles. I've heard estimates that place the energy release on impact with that of around 15000lbs of TNT, the explosive energy release is huge but the big blob of metal becomes millions of small pieces of metal that fly in every direction along with rocks and dirt moving at ultra high velocities from the impact site. And above all this the railgun projectile is under $500 in comparison to the $1 million dollar tag for the cruise missile.
The railgun essentially allows the USN to toss moderately sized meteorites at enemies. Whenever a naval article comes up everyone likes to talk about how vulnerable the USN is because of Sunburn and other antiship missiles. What they fail to realize is that once the DDX destroyers come online the fleet wouldn't even need to get in sunburn range to absolutely destroy even fortified coastal positions. Take a couple DDX destroyers and the new CDX carriers and you have a fleet that can sit 400 miles off the coast and bombard all the coastal defenses into oblivion before moving further in to bombard the cities and fortifications further in from the coast. The railgun projectiles also have extreme penetration, they can cut through 10's of feet of reinforced concrete with ease, and even underground facilities become susceptible as 10 projectiles could likely cut a massive hole and penetrate buried facilities that could then be followed up with bombs dropped from planes. There is also another advantage, cruise missiles aren't effective against mobile targets because it takes so long for them to get there, at mach 8 the railgun projectiles flight time is extremely small, along with the no advanced warning (no sound preceding impact) gives the projectile a much better chance at hitting mobile targets without having to use manned aircraft.
The USN is also trying to find guidance systems that can survive the G forces in the hope of having some minimal guidance.