33 Megajoules Pushing 23 Pounds

Video: Navy’s Mach 8 Railgun Obliterates Record

There wasn’t much left of the 23-pound bullet, just a scalded piece of squat metal. That’s what happens when an enormous electromagnetic gun sends its ammo rocketing 5,500 feet in a single second.

The gun that fired the bullet is the Navy’s experimental railgun. The gun has no moving parts or propellants — just a king-sized burst of energy that sends a projectile flying. And today its parents at the Office of Naval Research sent 33 megajoules through it, setting a new world record and making it the most powerful railgun ever developed.

Reporters were invited to watch the test at the Dalghren Naval Surface Warfare Center. A tangle of two-inch thick coaxial cables hooked up to stacks of refrigerator-sized capacitors took five minutes to power juice into a gun the size of a schoolbus built in a warehouse. With a 1.5-million-ampere spark of light and a boom audible in a room 50 feet away, the bullet left the gun at a speed of Mach 8.

Video and more at the Danger Room.


  1. Somebody’s numbers aren’t juggling correctly. Wikipedia lists the speed of sound (Mach 1) as:

    “The speed of sound is the distance traveled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds”.

    If the projectile was traveling at 5,500 FPS as stated in the first paragraph it was traveling at Mach 4.88. If the projectile was traveling at Mach 8 as stated in the third paragraph it was traveling at 9,008 FPS, not 5,500 FPS.

    If they did fire the 33 lb projectile at 5,500 FPS (Mach 4.88) it’s not much faster than 13 lb long rod penatrators out of the 120 mm smooth bores the Abrams and Leopard 2s use (though obviously the projectile weight and energy release are much greater from the rail gun). If the Mach 8 projectile speed is correct……………then it IS impressive. Now…………..if they can only get that rascal up to about 18 to 20,000 FPS! w00t!

  2. Because I’m math impaired, does anyone know of a sight that has information on the energy release of older cannon, say like those off a battleship? Someone was asking me this in comparison to the test firing success the Navy’s been having with the rail gun project.

  3. Hmm, had a thought…I wonder if a departure from the standard projectile design might be in order as the shells are not spin stabilized. Perhaps use some of the hypersonic aircraft lifing body design ideas to improve the flight characteristics and increase range…gotta be better than that squareish block they are chunking.

  4. “Did they have to harm the projectile?—-awwwwwww,

    Couldn’t they just talk everything over at thousands of feet per second and some giga-joules of open mindedness?—eeeeee,

    Ships and electricity are really just overcompensation for a lack of liberal idiocy—eeerrrrr,

    We should give all of this technology away to whoever we can identify as hating us so they will know peace is our mission—uuuugghhhh”—

    I could swear I saw the above as a Wikileked cable from some Obama liberal to some other traitor, but maybe I’m wrong.


  5. Flanker,

    You’re beating a dead technical horse with all your joule-jive jargon.

    Musket or railgun…..BOOM, the bad guy’s toast!

  6. It sounds fun, but this gun is way too impractical. 33 meagajoules is easily beaten by traditional big ship guns. The rate of fire is way too low and it wears out in a couple of shots.

    It’s like milking a dolphin instead of a cow.

    1. It’s like milking a dolphin instead of a cow.

      Ah, but you haven’t lived until you’ve had dolphin milk.

  7. Assuming I’ve done my sums correctly, kinetic energy in Joules is 1/2 the mass of an object time the square of its velocity in metres per second. Therefore:

    16″/50 Mk7 (B-61 Iowas) with 1225kg AP shell at 739 m/s is 334.5 MJ.

    5″/62 Mk45 Mod4 (DDG-51 Arleigh Burkes/CG-47 TiCos) with 30.7kg HE shell at 831 m/s is 10.6 MJ.

    6″/47 Mk 16 (All WWII 6″-gunned CL classes) with 59kg AP shell at 762 m/s is 17.1 MJ.

    8″/55RF Mk 16 (CA-134 Des Moines) with 152kg AP shell at 762 m/s is 44.1 MJ.

    So, Dahlgren has achieved muzzle energies in the middle of the range of the latest WWII era CLs and CAs. Their previous record was right at what the existing 5″ popgun can do.

    Gun data from here: http://www.navweaps.com/Weapons/WNUS_Main.htm

  8. Capn Ned,

    I think your numbers are correct. But here’s the appeal of the rail gun. When the 10 Kg projectile hits its target at 100 miles out, it is still travelling at Mach 5. This gives it the theoretical equivalent force of a 1000 lb Tomahawk warhead, with no explosives needed.

    So they effectively quadruple the range of the 16” guns, and eliminate the need for the 650 lb propellant charge and the 2700 lb mixed explosive/metal projectile.

    And instead of a ship carrying 40-50 Tomahawks, max, they can carry thousands of the 10 Kg projectiles. And it only takes a couple dollars worth of electricity to launch each one.

    They do expect the rails to wear pretty fast, but changing them should be pretty easy. I think their goal now is 100 shot life.

    Also, I believe the Army will be demonstrating a smaller rail gun on a tank in the next year or so. I think it is in the 8 MJ range, with a 4-5 pound projectile. Its projectile can supposedly penetrate 3 tanks stacked back to back.

    Rail guns are not sci fi anymore. Full discloser, I am biased. I am an electrical engineer who specializes in electromagnetics. I have a buddy at Dalghren, and I was seriously considering taking a job there a few years back. I am convinced that we will see rail guns deployed in the next 10 years or so, and I figured it would be a pretty good career move.

  9. Heres the big question, how many shots an hour? If they can’t get the firing rate up, these things are going to be useless for arty support unless you have multiple ships. How long to charge between shots? How many of these guns and capacitor banks are going to be needed to equal one [fill in your naval arty of choice] using conventional munitions? Will you be able to power this off standard non-nuke power plants, or to keep it combat effective [IE have enough juice to power it up fast enough to be useful] will we need to bring back the CGN class or create a BBN or DDGN class to feed it with a nuke plant?

    So far, chemical propulsion is still the king of ROF and “bang for your buck” if you will pardon the pun. Gotta admit though, they are getting closer. Yeehaw!

    Then again, I could be completely wrong. Just going for perspective.

  10. Right now the estimate is 10-12 rounds per minute per gun will be achievable in a few years.

    They really don’t use a whole lot of juice per shot. 32 MJ is about 9 kilowatt hours. They haven’t published efficiency numbers, but there has to be some loss. I’m sure the main concern will be how fast they can charge them back up after the banks are depleted.

    The initial plan is to put them on a destroyer type ship. I saw a graphic once, that I can’t find right now, but it showed North Korea as the “killer app” for a rail gun based destroyer. I think it was based on a 4 gun ship. With one stationed off their East and West coasts, they could take out every artillery piece in the country about as fast as the Norks could roll them out. If they can double the power (which is still the goal), then they can cover the whole country just from the ocean side.

  11. Nah you guys are missing the point. These rail guns mean the end of the brown water navy. China after letting us spend billions on R&D, Redirects the Internet and steals the designs. Builds about twenty across the tiawan straight and says game over I win.

    A slug traveling at Mach 8, will sink or cripple any ship it hits. There is not a current or projected defense from such a weapon. Chaff, ECM, flares, lasers, and even the R2D2 would be useless, moreover, the chances of a targeted ship even seeing the incoming round us next to nill. The RCS of the round would be a few centimeters at best. The only sure way to detect the incoming round is via infrared and that would only give you maybe a few seconds at best. Real time space assets and a iPhone would be all that you would need to compute the destruction of a battle group.

  12. “A slug traveling at Mach 8, will sink or cripple any ship it hits.”
    … energy transfer, dear boy … and the the necessity to hit one’s aiming point.


  13. “The gun that fired the bullet is the Navy’s experimental railgun. The gun has no moving parts or propellants — just a king-sized burst of energy… ”

    As soon as you can fit a shoulder thing that goes up it can get banned in Massachusetts.

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