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U.S. Navy’s electromagnetic railgun shatters records; five times speed of sound

By | December 17, 2010, 7:08 AM PST

The U.S. Office of Naval Research announced last week that it demonstrated a world record-breaking 33-megajoule shot by its new electromagnetic railgun.

A megajoule measures the energy of a mass traveling at a certain velocity; a one-ton vehicle moving at 100 miles per hour equals a megajoule of energy.

The weapon, located aboard the Naval Surface Warfare Center Dahlgren Division, means that the Navy can fire projectiles at least 110 nautical miles, keeping sailors and Marines further away from harm.

It also means those projectiles have even higher velocities, which can help for air and missile defense. A 33-megajoule shot could reach extended ranges with Mach 5 velocity — five times the speed of sound.

The Navy demonstrated a 10-megajoule shot in 2008.

The railgun is also beneficial because it could eliminate the need to carry a high-energy explosive warhead and traditional gun propellants. Obviously, reducing explosives and chemicals on board is not only safer, but simpler from a supply chain perspective.

Here’s a video of the 2008 shot:

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Andrew Nusca

About Andrew Nusca

Andrew Nusca is the editor of SmartPlanet.

Andrew Nusca

Andrew Nusca

Editor

Andrew Nusca is editor of SmartPlanet and an associate editor for ZDNet. Previously, he worked at Money, Men's Vogue and Popular Mechanics magazines. He holds degrees from the Columbia University Graduate School of Journalism and New York University. He based in New York but resides in Philadelphia.

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Andrew Nusca

Andrew Nusca
Andrew Nusca does not hold any investments in the companies he covers.
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0 Votes
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Cool.
I wonder if the US Navy plans to bring back nuclear powered cruisers to provide the power needed for such a weapon?

They scraped the last of them in the late 1990s.
Posted by Hates Idiots
17th Dec 2010
0 Votes
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Navy railguns
I don't recall the nuke cruiser decommissioning, but I think railguns would make a great contribution as onboard aircraft carrier defense.
Posted by jmwatl@...
23rd Jul
0 Votes
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Alien Weapons?
Cool, finally some high tech stuff for planetary defense happy
Posted by sotiris1@...
17th Dec 2010
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
I'm curious as to just where the electrical power to drive one of these "guns" would come from on a ship at sea. Most Navy destroyers and cruisers have ship's service generators that produce between 250 and 750KW (kilowatts), but if this weapon consumes 33 mega-joules, and draws that power for 1 second, then the conversion to watts is simple -- 1 joule = 1 watt/second -- so this weapon would draw around 33MW. That's many times more electrical juice than the ship can possibly produce. And if the ship has more than one of these weapons, well, you should see the problem. So, any ideas as to just how these ships would power such a "gun"?
Posted by dcwest
17th Dec 2010
0 Votes
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Capacitors.
You can store a lot of energy for nearly-instantaneous release if you have huge capacitors. A bigger problem is erosion. That huge fireball is plasma, like a lightning bolt tail pushing the projectile. It eats away at the rails, making each shot a little weaker.
I see this as a defensive weapon trying to shoot down an incoming missile. If you can get it in two or three shots, you've saved the ship. If you can't, damage to your rail gun becomes a moot point.
Posted by kidtree
17th Dec 2010
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
In the game of Battletech, they use portable tokomak reactors to power their gauss canons. These work great on paper, so long as all of your combat occurs on paper. The minute somebody starts throwing dice, though, they're pretty useless.
Posted by grassdogstudio
17th Dec 2010
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
There would be energy storage issues in addition to the energy generation issues that dcwest mentioned.
A bit of perspective: The Navy has tried to get better "big guns" for warships at least twice before. Both of those projects flopped. This go around has far more issues with new technology than those previous attempts.
Posted by hoodedswan
17th Dec 2010
0 Votes
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"Railguns: and "Gauss Rifles"
grassdogstudio is right as far as he takes it; the Battletech game used miniaturized Fusion reactors to power the piloted robots called Battlemechs (or just 'Mechs) in the game world. However, those 'rail guns' did NOT fire their gauss rifles off a rail. Those monsters launched a metallic BALL shot, using a magnetic suspension field - in effect, the shot was held in a mag field, so it did not touch any part of the cannon's "Barrel" during the launch sequence.
Now, right now, the USN can't do that - at least, not as far as I know. SO the Gauss Rifle of the BattleTech wet dream is just that - a dream. Ditto for the power supply - at least, I don't know of any fusion reactors walking, riding, sailing, or otherwise operational on THIS planet. Darn it!
Rectify THOSE two missing parts, and the Navy has it beat - but then, so does the Army, ConEdison, BGE, PPE, and every OTHER electric power company! Not to mention all the car manufacturers, etc.
Posted by MadYank
17th Dec 2010
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
It probably takes less than 1/10th of a second for the gun to discharge. Maybe much less so you don't have to have as much power available as you might think.
Posted by riverat1
17th Dec 2010
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
There might be one "old-tech" way to generate the very short but high-energy bursts needed for this weapon. The Navy has for several decades used motor-generator sets to isolate the short bursts of power needed for its active sonar systems from the stable but much lower power of the ship's generators. In this technology, a motor drives a large, balanced flywheel that in turn drives a generator capable of producing the short bursts necessary for the sonar (some of which draw as much power as the ship's generators can produce). While idling, the motor spins up the flywheel to a fairly high speed, then during the burst, the generator puts such a high load on it that it actually slows down the flywheel. Then the system waits again for the motor to speed up the flywheel for the next burst. Whether this old technology is capable of producing the extraordinarily high burst energy needed for this weapon is, however, another very good question, and like many new weapon technologies, may be a classified secret.
Posted by dcwest
17th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Forgot to add . . . . as far as I know, our current technology in nuclear reactors does not produce electricity from the nuclear reaction. Instead, the reaction produces heat, that super-heats water that goes through a heat exchange system to heat other "clean" water (so as to contain the radioactive water as much as possible), then this "clean" water is used to drive steam turbine generators. This design produces stable electrical power, but essentially no "burst" capability. Presumably this is also true of the experimental Tokamac reactor built at Princeton in the 1980's, in which the Tokamac field was intended to contain the reaction enough to produce a controlled fusion reaction, but that reactor closed in 1997 without ever having successfully creating a controlled fusion reaction.
Posted by dcwest
17th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
riverat: "It probably takes less than 1/10th of a second for the gun to discharge. Maybe much less so you don't have to have as much power available as you might think"

Power is work (energy) per unit time. Decreasing the time INCREASES the power required,

I was intrigued that despite all the unit differences between US and metric, 1 ton at 100 mph is almost exactly 1 megajoule. Had to check it myself before believing it.

One MJ would require a pretty big flywheel. A 1,000 Farad capacitor bank charged to 1,000 volts would hold 1 MJ. Any electrical engineers out there who can tell us is this is practicable?
Posted by 0David
18th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
"The weapon, located aboard the Naval Surface Warfare Center Dahlgren Division,"

Last time I checked the "Naval Surface Warfare Center" is in a very land locked albeit peninsula of Chesapeake Bay. I am not sure but may be it has decided to go wandering about in the ocean.
Posted by randall.wilkinson@...
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Unfortunately at present, most high capacitance capcitors are low voltage. See the Capattery from Evans Capacitors, they have a 1.5 F capacitor it is only 5.5v, though. I had forgotten that to attain a higher working voltage, one needs to have them connected in series.
Another instance of very high capacitance is in an article from Power Electronics Technology magazine: http://powerelectronics.com/mag/power_ec_capacitors_deliver/
EC Capacitors Deliver High Capacitance in a Small Size
Mar 1, 2001 12:00 PM
Daniel O'Brien, North American Capacitor Corp., Greencastle, Ind.
So a high capacitance capacitor bank is feasible, not necessesarily practical.


Single-cell EC capacitors can reach 50,000 + farads
Posted by dhays
20th Dec 2010
0 Votes
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Navy railguns
What about recharge time?
A primary consideration for a defence system, which I see as the major potential contribution for the RG, unless it would be feasible for launching satillites.
Posted by jmwatl@...
23rd Jul
0 Votes
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Something suspicious about that video
The projectile looks suspiciously like it was fired with a conventional propellant. In slow motion, all the flame is confined to the back end of the projectile; none from the sides, and absolutely no sign of heating of the front end.

Impact with the target should have caused disintegration of the projectile; yet it looks fully intact after passing through the target.

Seems to me that there really are no signs of the video projectile being of hypersonic velocity.
Posted by Dr_Zinj
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Film runs too fast, including the descriptor text at the beginning. You
can't expect the human eye to deal with such speeds unmodified.
Posted by shanedr
20th Dec 2010
0 Votes
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Just to add
Previous post overlook one issue: we do not need high voltage - wee need high current that usually melts the rails. In basic railgun amount of current passing through the rails and projectile is directly related to the force applied to the projectile. However, high current, reduced friction and smal projectile created an only major problem: prjectile melts to the rails. Increasing the size of projectile has produced the results other posters talked about: huge systems that require tremendous amount of energy.
Posted by sashkashurik
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Forgot: Railgun is thereticly feasible and the energy is not the only problem. Superconductors, energy, moving parts(that are also conductors) etc, all together create the major problem for constrcution of this weapon.

As for the video, at this speed the compression of the air infront of the projectile and the heat produced by the movement at this velocity will create the trail of fire and will destroy the object long before the projectile reaches them.
Posted by sashkashurik
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Hey, why don't they start using some of Stanley Pons' cold-fusion reactors? They have lots of seawater!
Turn the whole ship into an anode. And use another warship as a cathode! wink
I'm sure this would work. Why 20 years ago, all kinds of respected physicists in our universities had told us that "it worked!"
That is, until the secret oil-companys cabal shut them up!
Posted by PercySludge
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Addendum: Why is this news contained in a website called "Smart Planet"? Only sayin'...

As for me, I'm currently trying to develop massive amounts of electricity out of Toxic Sludge! Now THIS will smarten the planet!
Posted by PercySludge
20th Dec 2010
0 Votes
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How it works
Here's one guy's railgun project, with theory, problems, and results, plus a link to his upgraded version. Lots of photos & a video.
http://www.powerlabs.org/railgun.htm
Posted by kidtree
20th Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic(?) railgun shatters records
hmm... that projectile has an odd shape. Just play the video frame by frame and you'll see it. To me it seems to be hollow in the front part, then it's the cylindrical body, a small tightening, then 2 (maybe 3, a 3rd fin presumed to be behind the flame) stabiliser fins.
Just a Theory (I'm no rocket scientist): The projectile is a ramjet, with a small fuel cartridge inside. The EM gun accelerates the projectile up to, let's say Mach 1 or 2. Then the ramjet takes over and the projectile goes Mach 5.
Posted by p12p11@...
21st Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
As a point of reference on the use of capacitors in this
application: In the 1960s I was on a small oceanographic
research vessel (former WWII Navy Diver Class salvage tug). The
small ammo locker contained a bank of capacitors used to
discharge a 10KV, 0.1 MJ spark every 3 seconds for seismic
profiling. The capacitor bank did not fill the locker, and the timing
was determined by echo return times from the ocean floor
substructure--meaning it was likely possible to shorten that
interval. Much larger vessels and improvements in capacitor
efficiency and power generation since then might indeed allow
this method to work as a railgun power system.
Posted by spyderay
23rd Dec 2010
0 Votes
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RE: U.S. Navy's electromagnetic railgun shatters records; five times speed of sound
Whatever happens to compressed carbon dioxide? CO2 is the most compressible gas around known to mankind which mean you cant reduce the volume of the C02 under any level of pressure.. If you fill a cubic feet with CO2 at sea level pressure and pressure it to some crazy level like zillions pounds per sq inch, the volume will stay the same no matter what. This is what is so great about carbon dioxide. The problem is sealing the pressure before firing. It will leak or hiss so loudly before you can fire it.. even through hairline leaks.. CO2 is the best explosive around but you got to find a real good sealing material to keep the gas under great pressure before firing . We have BB guns that can fire BB shots almost as fast as anything with carbon dioxide cylinders. BB shots that can kill you, eh?
Posted by brettze
27th Dec 2010
0 Votes
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re: CO2
CO2 is a gas. Gases compress according to physical law. Compress it a zillion times and its volume is one zillionth of a cubic foot. Depending on what a zillion is, it may become liquid, solid or a denser material (elementally) when it cools.
Posted by MagnetBoy
14th Jul 2011
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