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The Military United States

Navy Debuts New Railgun That Launches Shells at Mach 7 630

Jeremiah Cornelius writes: "The U.S. Navy's new railgun technology, developed by General Atomics, uses the Lorentz force in a type of linear, electric motor to hurl a 23-pound projectile at speeds exceeding Mach 7 — in excess of 5,000 mph. The weapon has a range of 100 miles and doesn't require explosive warheads. 'The electromagnetic railgun represents an incredible new offensive capability for the U.S. Navy,' says Rear Adm. Bryant Fuller, the Navy's chief engineer. 'This capability will allow us to effectively counter a wide range of threats at a relatively low cost, while keeping our ships and sailors safer by removing the need to carry as many high-explosive weapons.' Sea trials begin aboard an experimental Navy catamaran, the USNS Millinocket, in 2016."

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Navy Debuts New Railgun That Launches Shells at Mach 7

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  • No jetpacks yet... (Score:5, Insightful)

    by occasional_dabbler ( 1735162 ) on Wednesday April 09, 2014 @02:05PM (#46706511)
    ...but at least part of the future is here already.
  • by errxn ( 108621 ) on Wednesday April 09, 2014 @02:09PM (#46706537) Homepage Journal

    ...Can someone who is explain where the big fiery explosion out of the railgun is coming from, if this thing is electromagnetically driven?

    • by Anonymous Coward on Wednesday April 09, 2014 @02:11PM (#46706569)

      Hot expanding gases, you're pushing a projectile at Mach 7 through air that doesn't really have anywhere to go.

      • by errxn ( 108621 )

        OK, hot, yes, but wouldn't they need something combustible to actually erupt into flame? Or what am I missing?

        • by PortHaven ( 242123 ) on Wednesday April 09, 2014 @02:16PM (#46706635) Homepage

          Oxygen, it's in the air...

          fine vaporized particles of metal...


          • by Savage-Rabbit ( 308260 ) on Wednesday April 09, 2014 @06:00PM (#46708813)

            Oxygen, it's in the air...

            fine vaporized particles of metal...


            And that, ladies and gentlemen, is a demonstration of what we science nerds like to call 'simple science for senators". The amazing thing about it is that you can actually get billions of dollars in funding using this simplified approach when brilliantly researched and written scientific papers fail miserably. Go figure!?!?

            • Re: (Score:3, Insightful)

              by BitZtream ( 692029 )

              Brilliantly written papers are ones that explain the subject matter in an understandable way to the target audience.

              You don't send the same paper to theoretical physicist as you send to a senator.

              If you don't realize that, you're not anywhere near as smart and clever as you think you are. Do you expect a guy who's job is politics to REALLY ALSO know all the same shit as the guy who spends his entire life working on the physics of it? Are you really that unaware of the people in the world around you not al

        • by Moheeheeko ( 1682914 ) on Wednesday April 09, 2014 @02:16PM (#46706641)
          Oxygen is pretty combustable if you get it hot enough. Friction is a bitch yo.
        • The nitrogen under pressure remains inert, but the oxygen will combust at those levels. There's a great video of the plastic block they were testing with years ago with a huge wall of flame behind it as it traveled at mach 5 iirc...

        • by Immerman ( 2627577 ) on Wednesday April 09, 2014 @02:37PM (#46706873)

          Actually, do we know that there's any burning going on at all? I believe the light from a fire is not directly emitted by the chemical reaction, it's a result of the combustion gasses glowing from the heat. In which case just heating even an inert gas sufficiently will cause it to glow similarly. And the immense high-speed compression from a mach-7 projectile traveling down a confined tube should generate plenty of heat.

          • that's actually a good point. think of a shooting star (meteor). There's no fuel here either, just a red hot rock and red hot air flowing behind it.

          • Yes, an ionized gas glows on its own, just like a neon light. I don't know if this is the case though. The case someone made above about the oxidization of fine metal particles seems plausible, too.

            In the case of a normal fire though, the glow comes from the red-hot soot particles that come from the inefficient combustion of carbon fuel, so it's not the gasses glowing from the heat.

        • by MozeeToby ( 1163751 ) on Wednesday April 09, 2014 @02:44PM (#46706933)

          "Flame" is nothing but superheated gases. You can have a flame without combustion if you raise the temperature some other way. In this case it's electrical heating, ram air pressure, and simple air friction.

        • by Man Eating Duck ( 534479 ) on Wednesday April 09, 2014 @04:24PM (#46707971)

          OK, hot, yes, but wouldn't they need something combustible to actually erupt into flame? Or what am I missing?

          I think this is what's going on: when something is burning, the flame you see is just glowing hot air, heated by the energy from the combustion. The flame is not part of the combustion, just the side effect. In this video you see glowing hot air heated by compression and possibly the shock wave from the projectile. Same result, but the energy source is different.

          If you've seen a meteor (streak of light in the sky at night, or a visible fireball with a trail if you're really, really lucky), the principle is the same, nothing is burning. The heat come from compression of the air in front of it, and the light you see is from the superheated air in its wake (and a little from the glowing meteorite).

    • by peragrin ( 659227 ) on Wednesday April 09, 2014 @02:12PM (#46706577)

      It is called plasma. It happens when you heat gases beyond a particular limit.

      A 23 pound slug traveling at Mach 7 is displacing a lot of air very quickly.

      Do you think that air will get colder?

    • Just speculation but, when you propel something to mach 7, friction becomes a real issue. The SR-71 had a titanium body if I recall correctly, to help deal with temperatures it encountered at Mach 3. It is quite possible that the projectile is very hot and is igniting materials that have lower ignition temperatures.
    • by occasional_dabbler ( 1735162 ) on Wednesday April 09, 2014 @02:50PM (#46707009)
      This is simple. You are making the air near the missile move at Mach 7.

      The temperature of the air will be around ten times ambient, so 3000K, which is more or less the stochiometric temperature for hydrocarbon fuels.

      Read this [cfd-online.com] for details of the isentropic flow relationships.

  • Power? (Score:4, Insightful)

    by asmkm22 ( 1902712 ) on Wednesday April 09, 2014 @02:09PM (#46706545)

    Can it be efficiently powered, though? It always seemed like the power draw was the main issue with these kinds of guns, effectively limiting them to a few shots.

    • Future Aircraft Carrier, USS-Nikola, to be constructed primarily of Lithium-Ion Batteries.
    • New cruisers and carriers just coming out were spec'd to have 3x-6x power generation. New carriers are getting rid of steam catapults in lieu of railgun catapults as well.

    • Re:Power? (Score:5, Informative)

      by Solandri ( 704621 ) on Wednesday April 09, 2014 @02:59PM (#46707131)
      23 lbs = 10.5 kg
      Mach 7 = 5300 mph = 2382 m/s
      KE = 0.5mv^2 = 59.6 MJ

      The ship in question has four 9100 kW diesel engines (12,200 hp).

      Assuming you have a big enough capacitor, the output from just one diesel engine should be enough to power a round every 6.5 seconds. There are conversion and efficiency losses, so probably every 15-20 seconds is more realistic.

      Also note that 59.6 MJ is about equivalent to 14 kilos of TNT. So the energy yield of this will be on the order of a high explosive round from a 5 inch shell (which weighs about 30 kg), assuming the projectile doesn't pass entirely through the target.
  • SWATH, not Catamaran (Score:5, Informative)

    by n1ywb ( 555767 ) on Wednesday April 09, 2014 @02:13PM (#46706591) Homepage Journal
    It's a "Small-waterplane-area twin hull" or SWATH, not a catamaran. http://en.wikipedia.org/wiki/S... [wikipedia.org]
    • Potato, potahto.

      • Hydrodynamically, they are completely different. A catamaran's hulls displace water at the surface (and below). Its drag consists of both friction and waves generated by that displacement. A SWATH gets buoyancy from completely submerged hulls and minimal distortion of the surface. In the ideal case (hulls are sufficiently submerged), its drag consists entirely of friction.

        Normally a SWATH design is used on slow-moving ships where stability is paramount (having the buoyancy underwater means your ship
  • "They are firing, sir!"
    "Prepare the counte...."

    Seriously... 100 mile range? At 5000mph? That range doesn't add up to me, but regardless, whoever is on the receiving end of this bad boy doesn't stand a chance to defend themselves

  • by war4peace ( 1628283 ) on Wednesday April 09, 2014 @02:14PM (#46706615)

    That's not even a 75mm railgun size. Can I fit it on my Velator? :)

  • Finally (Score:5, Funny)

    by bitt3n ( 941736 ) on Wednesday April 09, 2014 @02:23PM (#46706723)
    At last the US Navy, for so long the joke of the high seas, will become a force to be reckoned with.
  • Mach 7? (Score:5, Funny)

    by K. S. Kyosuke ( 729550 ) on Wednesday April 09, 2014 @02:29PM (#46706801)
    Well, judging form the pictures, this is the one disposable razor I wouldn't want to be shaved with.
  • by Anonymous Coward on Wednesday April 09, 2014 @02:31PM (#46706821)

    Not to nitpick (well.....yah, I'm nitpicking), but both General Atomics and BAE Systems Railguns will be tested on the USNS Millinocket. BAE Systems actually got the Phase II contract, whereas General Atomics did not.

    Link: http://breakingdefense.com/2014/04/navys-magnetic-super-gun-to-make-mach-7-shots-at-sea-in-2016-adm-greenert/

    Full Disclosure: I nearly got to work on the GA RailGun system and I know some people who are on it. It's a better design than the BAE one but BAE got the contract.

  • So... (Score:5, Funny)

    by msobkow ( 48369 ) on Wednesday April 09, 2014 @02:40PM (#46706895) Homepage Journal

    So we're back to throwing rocks.

    We just throw them very, very fast. :)

    • Re:So... (Score:5, Interesting)

      by smartr ( 1035324 ) on Wednesday April 09, 2014 @03:31PM (#46707457)

      I found it interesting to describe by calculating kinetic energy. A stabbing ~ 185 joules. A gunshot of 45 caliber ACP round ~ 702 joules. A 1 ton vehicle going 100mph ~ 1 megajoule. A giant truck about to hit a series of tubes ~ 30 Megajoules. The kinetic energy of this railgun as it leaves the muzzle ~ 30.9 Megajoules.

      • Re:So... (Score:5, Insightful)

        by nitehawk214 ( 222219 ) on Wednesday April 09, 2014 @04:36PM (#46708079)

        And better.. (or worse, if you are the target)... all 30MJ is hitting you in a spot about 10cm in diameter.

  • by floobedy ( 3470583 ) on Wednesday April 09, 2014 @02:42PM (#46706915)

    Perhaps one of the big benefits of a naval railgun is that it's so difficult to defend against. Old-fashioned anti-ship missiles can be disabled or destroyed by the defending ship's close-in defenses [wikipedia.org]. This is because the incoming missile is filled with sensitive electronics, guidance systems, explosives, fuel, turbojet engines, stabilizing fins, etc, and is very likely to be damaged or destroyed if hit by a 20mm round from the defending ship's CIWS missile defenses.

    However, how do you shoot down a hunk of metal traveling at mach 7 toward your ship? It wouldn't make any difference if you hit it with a 20mm round from the goalkeeper [wikipedia.org] or phalanx [wikipedia.org]. The projectile would just keep flying toward the ship and strike it anyways. Besides, how would you even hit something which is so small and traveling at mach 7.

    It doesn't seem there would be any good defense against this.

  • by bobbied ( 2522392 ) on Wednesday April 09, 2014 @02:44PM (#46706935)


    Imagine if you didn't need to handle explosives like Cordite as propellents anymore. This will reduce storage space and make a battleship's gun turret a while lot safer place to work. One small spark won't set off a magazine anymore.

    "Muzzle velocity" is higher, so the distance you can throw something is a bit further, like 5x further. If you can fire further, you have a huge advantage because you can hit your opponent before he can shoot at you. Or if you are doing ground support, you can fire further inland.

    I'm assuming a rail gun will be faster to reload. Might take some time to recharge the power supply, but surely we can fire faster than a Mark 7's 2 rounds a minute. More pounds and rounds on the target than your opponent is always better.

    Finally, it may be possible to more strictly control forces on the shell when firing it, which may make it possible to put more technology IN the shells, and still get very high velocity. Imagine a shell that can adjust it's flight path, even slightly, which means you can fire in the general direction you want, then fine tune the aim in flight. (I assume they don't do that now..)

    Issues to watch out for: First, Rail guns tend to have tracks (rails) and said rails usually have difficulty with wear due to the huge forces and high speeds involved. Hopefully they have engineered the better materials. Second, power supplies for rail guns have to be designed to provide HUGE impulse powers with power generation systems wanting to be running at steady state. You have to match the two. Finally, weapons like this usually mean you have to redesign the whole weapons system, a process that literally takes decades.

    Go Navy, this is worth the R&D money..

The last thing one knows in constructing a work is what to put first. -- Blaise Pascal