back to article No hypersonic railguns on our ships this year, says US Navy

The US Navy is not bolting its new electromagnetic railgun to any of its warships in the coming year, a move sure to disappoint those who rejoice at innovative methods of blowing stuff up. The naval service's budget for fiscal year 2018 contained no funding requests for putting the USN's electromagnetic railgun (EMRG) on a …

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  1. Aladdin Sane Silver badge

    Will it fit on a shark?

    Or ill-tempered sea bass?

    1. Anonymous Coward
      Anonymous Coward

      Re: Will it fit on a shark?

      Depends on how loosely you accept the term fit, the prototype I saw was roughly the size of what you see in old WW2 AA deck cannons and the mount it was on, so if attached would shortly be sinking to the bottom together.

      1. DougS Silver badge

        Re: Will it fit on a shark?

        So you're saying it needs to be attached to a blue whale?

        1. Marketing Hack Silver badge

          Re: Will it fit on a shark?

          Blue whale? No! Sharktopus!!

          1. Jellied Eel Silver badge

            Re: Will it fit on a shark?

            We're gonna need a bigger shark!

            Or a better power source.. Like a few RR PWR's stuck in any spare spaces on out carriers. They work, railguns.. perhaps less so, unless they've overcome problems with rails warping or eroding.

  2. BoldMan

    Well since the RN have trouble with power plants that can generate enough power for existing ships. I doubt if we'll see this for a while...

    1. macjules Silver badge

      We were going to have EMRG on our new carriers. Unfortunately the cuts have ensued that the only way we can generate enough power to fire one round will be to add two 300m wind turbines to the back of the HM QE class carriers.

      I understand that our erstwhile Defence Secretary Fallon has approached every naval officer and requested that, in accordance with other proposed UK social laws, they hand over their parent's houses in order to pay for the EMRG project.

  3. TDog
    WTF?

    Optional explosive charge?

    "enabling an explosive charge on the rear of the projectile to be carried deep into the vulnerable heart of an enemy ship, tank or bunker"

    That's some serious dynamics, putting an HE charge at the back of a LRP travelling at 1500ms^-1 or faster. Methinks a tad too enthusiastical reporting.

    1. DougS Silver badge

      Re: Optional explosive charge?

      I think the LRP traveling at that speed would do so much damage on its own, an explosive tip (or explosive ass in this case, I guess) is superfluous. There will be a lot of shrapnel from the armor plating and various walls/decks it penetrates on its way to the vulnerable heart of an enemy ship, plus some from the projectile itself as it hits all that stuff and fragments.

      1. Tank boy

        @ DougS Re: Optional explosive charge?

        The word you are looking for re: "all that stuff and fragments" is spall. On American tanks they issue vests to protect us. I never was really sure I wanted to test it for real, but 'They' said it would work (I actually think 'They' said "It's better than nothing", but I wasn't at that meeting) in the event of a tank fight.

    2. Ian Michael Gumby Silver badge
      Boffin

      @TDog Re: Optional explosive charge?

      No, you could do it...

      I just don't want to be near the gun when you're doing the initial life fire testing.

      You have exploding 50 cal BMG bullets so why not a rail launched projectile? the trick would be in the fuse.

      1. Triggerfish

        Re: @TDog Optional explosive charge?

        Looking at the patent it looks like the outer core hits something like deck armour and initially punches the hole, then momentum lets the inner core keep traveling through the hole made.

    3. phuzz Silver badge

      Re: Optional explosive charge?

      If you can fit a terminal guidance system into an artillery shell that can survive being fired, an explosive charge in a railgun projectile should be easier.

      (I know the railgun accelerates harder, about 30,000G by my guess, vs 15,000G for the artillery shell, but the guided shells have moving parts, whereas an explosive device could be solid state. That said, it turns out the US Navy want GPS guided railgun rounds, so that'll be an interesting challenge).

      1. TDog

        Re: Optional explosive charge?

        You could do but there are a couple of significant points:

        LRP's are long and thin, for several reasons - reducing air resistance; reducing cross sectional area on target whilst having a lot of momentum; when they hit an armoured target they do not burst through like a WW2 tank gun shot - they ablate at the tip whilst burning / evaporating / distorting / melting the armour hit. This actually causes the penetrator to shorten as it ablates.

        Any high explosive content would be an extremely small amount of explosive as the need for thick walls in the HE containing portion of the rod to prevent distortion under G forces multiple times higher than the launch conditions. Acceleration occurs in a barrel multi meters long, deceleration over a few centimetres as the rod hits an immobile target.

        With a normal shell it is much fatter, hits the target at a much slower velocity, and either bursts on impact or in the air. If it is an armour piercing weapon then it may use the Monroe effect or have a very thick case and high mass to penetrate. (See for example the GBU-28).

        Finally - should an LRP penetrate armour the subsequent ingress of very high velocity liquid and vaporised metals along with the LRP itself cause more than sufficient damage to the target.

        So you could in theory, and in practice, add an explosive back end but this would be a small volume, hugely expensive and not effective.

        1. gazthejourno (Written by Reg staff)

          Re: Re: Optional explosive charge?

          Fair enough. My experience is entirely small arms based - was thinking of the equivalent of API.

      2. DougS Silver badge

        @phuzz

        It isn't the acceleration in G's destroying the barrel, but the Mach 7 exit velocity. Artillery exits at a much slower speed.

    4. Anonymous Coward
      Anonymous Coward

      Re: Optional explosive charge?

      The patent linked to by the article http://www.google.co.uk/patents/US5275109 makes no mention of an explosive element in any design of long rod penetrator - either prior art or the patented improved version.

      The patent states: "The penetrating capability and effectiveness of the projectile depends fundamentally on its kinetic energy." and goes into a lot of detail about how the big problem is making something with appropriate mechanical strength: apparently, the two main trade off points are between "hardness needed for penetration and ductility needed for maintaining structural integrity" bearing in mind that if the LRP's too heavy, the gun's going to suffer excessively.

      I'd guess that a long rod penetrator with an HE back end would perform worse than a purely KE design.

      Also, the original article states:

      "The resulting kinetic energy causes devastating damage once it hits something, particularly compared with current explosives-based propellant technology."

      Umm... Existing kinetic energy penetrators are pretty devastating, you know - I've just looked up a few things on Wikipedia (yes yes I know, but...) and apparently the cancelled "Compact Kinetic Energy Missile" which is stated to have reached Mach 6.5+ (relatively close to the railgun's supposed Mach 7) delivered a penetrator with 10 MJ of energy, claimed to be "about the same as with 120 mm L/44 APFSDS munition" - i.e., this railgun's KE penetrator's speed is entirely comparable with current explosive-based propellant technology, which itself is similar to what's been achieved using rocket power.

      The railgun is only going to be much more devastating if it can fire a much heavier projectile - can it?

      https://en.wikipedia.org/wiki/Compact_Kinetic_Energy_Missile

  4. Anonymous Coward
    Anonymous Coward

    Downsides

    Wasn't one of the other significant downsides the tendency of the railgun to destroy its own barrel quite rapidly? ISTR that was a big problem with early railgun experiments.

    1. Ledswinger Silver badge

      Re: Downsides

      A perennial problem with any form of gun, and seemingly more significant as size of the projectile increases. If you're just lobbing lots of shells in the general direction and hoping a few hit (WW2 style) the barrel wear isn't significant. If you're hoping for accuracy then even the RN Kryten will wear its barrel out after about what, 200 rounds, which it could in theory deliver in about eight minutes of max rate shooting.

      With a rail gun (or any hypersonic gun) you'll never get high fire rates due to heat and wear issues, so accuracy is vital....and the whole idea starts to unravel once you need more than a six shot wonder.

      1. Anonymous Custard Silver badge
        Headmaster

        Re: Downsides

        I'd also wonder about EM shielding efficiency, and if anything went adrift the risk of basically subjecting your own vessel's electronics to an EMP burst and toasting your circuits.

      2. Korev Silver badge

        Re: Downsides

        Is there some way that wear could be measured and then taken into account whilst aiming so the "gun" lasts a bit longer?

    2. Mage Silver badge

      Re: Downsides

      Yes, they currently last for about 4 shots!

      1. Mark 110 Silver badge

        Re: Downsides

        So those scifi books I read where they built a 4 kilometer long rail gun up the side of a mountain to launch things (including manned craft iirc) into low earth orbit were bollocks then. Oh well.

        1. Ian Michael Gumby Silver badge
          Alien

          @Mark 110 Re: Downsides

          Those would be slightly different and would have a longer track in which to accelerate the projectile since it would 1) be larger and 2) carry soft fleshy bits known as puny Humans.

        2. Gary Bickford

          Re: Downsides

          The going-up-the-mountain launcher was a coilgun IIRC, not a rail gun. Big difference. A coilgun is technically similar to a maglev train, using sequential magnetic fields to accelerate a vehicle. A railgun pushes huge doses of current through the projectile (actually a sabot that carries the projectile. Railguns can accelerate much faster. A coilgun/maglev in an evacuated tube (see also Hyperloop), going about 45 degrees upslope to above 20,000 feet and about 100 km long could replace most or all of the first stage of a launcher.

          The biggest issues, beyond the sheer building of the machine, are the sudden insertion into atmosphere (albeit less than 50%) when the thin plastic barrier at the top is breached at Mach something, and the survival of the vehicle in hypervelocity travel through the remains of the atmosphere. But it is probably doable, and if/when space launches become more than a daily occurrence, the economics might start to look pretty good.

          Another issue - such a thing can only launch into one orbital plane, and it takes significant energy to change inclination.

    3. DougS Silver badge

      So get rid of the barrel!

      I've always wondered if they could avoid the whole wear issue by using superconducting magnets so the projectile never actually touches the "barrel". A weapon that destroys itself after a few shots, or even a few dozen shots, isn't much good for anyone but the defense contractor!

      1. Gary Bickford

        Re: So get rid of the barrel!

        I think you are thinking of coilguns, which use magnetic fields to accelerate - like maglev trains and the Hyperloop. A railgun uses huge current going across the sabot that carries the projectile. Even just using the magnets to keep the pieces separated, I suspect that the current density is so high that it would quench any known superconductor.

      2. Tom 7 Silver badge

        Re: So get rid of the barrel!

        They could at least get rid of the bit of the barrel that doesnt do the acceleration bit - not quite sure what the purpose of that is.

        1. SkippyBing Silver badge

          Re: So get rid of the barrel!

          'They could at least get rid of the bit of the barrel that doesnt do the acceleration bit - not quite sure what the purpose of that is.'

          Increases the accuracy and makes aiming easier.

          1. DougS Silver badge

            Re: So get rid of the barrel!

            Or you could have a bunch of barrels that can be rotated into place after one is destroyed. Sort of like a revolver. More expensive? Sure, but the defense contractor won't mind on a cost plus bid!

      3. Meph
        Boffin

        Re: So get rid of the barrel!

        @ DougS

        AFAIK the projectile doesn't touch the sides of the barrel with current generation railguns. The warping and erosion is caused by the high energy plasma that is generated as the round transits the EM field that is accelerating it.

        All the test firing sequence videos I've seen for early prototype linear mass accelerators has shown the accelerated object leaving the device amid a huge fireball.

    4. Alan Brown Silver badge

      Re: Downsides

      "ISTR that was a big problem with early railgun experiments."

      It's been a problem probably a lot longer than you think - the Nazis had the same problem back in the mid 1930s.

    5. a_yank_lurker Silver badge

      Re: Downsides

      Barrel wear or the equivalent will be a problem. The question is how many shots can be fired before replacing the barrel couple with how easy is to replace the barrel. Note many modern machine guns have a field replaceable barrel that takes may be a minute to change. So if the barrel can be swapped at sea reasonably quickly by the crew it might not be take big an issue. You would consider the barrel a part of your normal supplies and make sure the ship has a couple of spares.

      Note barrel wear has been a problem for all rifled guns to some degree. The WWI Paris Gun had severe problems with barrel wear. If I remember correctly each round was slightly larger than the previous round and they had to be fired in the correct order to even hit Paris.

    6. cortland

      Re: Downsides

      Bingo! They had the POWER.

      http://nationalinterest.org/blog/the-buzz/us-navys-railgun-dream-could-be-denied-by-two-big-problems-17301

  5. Banksy
    Coat

    Long Rod Penetrator

    Hurr, hurr, hurr.

  6. Kevin McMurtrie Silver badge

    No budget? No problem!

    I bet the Russian government would install the system with easy financing. Just send a Tweet with a link to the schematics.

  7. James 51 Silver badge

    I read recently that new russian tanks had a new point defense system which made traditional anti tank weapons ineffective. Was this more smoke and mirrors or is it for real?

    1. ecofeco Silver badge

      Here's the video:

      https://www.youtube.com/watch?v=YpmcmKwWzYo

      Here's some active armor by other countries.

      https://www.youtube.com/watch?v=AUVnNk0aJBE

      British electric armor. That's right, electric armor

      https://www.youtube.com/watch?v=o7rxBifd0cY

  8. The Nazz Silver badge

    All well and good but ...

    how effective is it against white vans and three religious nutters armed with knives?

  9. Anonymous Coward
    Anonymous Coward

    That's what they want you to think

    "The US Navy is not bolting its new electromagnetic railgun to any of its warships in the coming year"

    Nope, not gonna happen. So all you Decepticons are safe. We promise. Especially around Egyptian pyramids.

    No, I don't know why any mention of railguns on naval vessels makes me think of that movie.

  10. DougS Silver badge

    Railguns vs lasers

    The last paragraph of the article seems to equate the two, but I don't think they are remotely comparable - other than both potentially being able to shoot down incoming missiles. A laser never runs out of "ammo", while a railgun isn't much good when you run out of rods (or sooner, if the barrel wears out)

    On the other hand, a laser can't hope to penetrate armor (unless they get a few orders of magnitude more power) while a working railgun would make armor on a ship or a tank within range of a ship effectively useless.

    1. ratfox Silver badge

      Re: Railguns vs lasers

      Serious military-grade lasers work on large quantities of chemical fuel, and they do run out of ammo.

    2. Alan Brown Silver badge

      Re: Railguns vs lasers

      "a railgun isn't much good when you run out of rods"

      True, but if you're not having to carry round 3-4 bags of cordite per shell (of about the same size) then you can fit a lot more of them onboard - and one of the bigger problems with needing the cordite is what happens when something coming the other way gets into your powder magazine.

      1. Baldrickk Silver badge

        Re: Railguns vs lasers

        But when you need an extra barrel for every 4 shells, the mass savings are not exactly positive any more.

        Where you save is in the supposedly vastly better accuracy and penetration power - if it takes 1-2 shots to take out a ship, rather than say, the 20 or so* you would have to fire to reliably take out an enemy ship in WWII era (*estimate off the top of my head, thinking about ranging shots, misses, non-penetrations etc) then you do need less.

      2. M7S
        Coat

        Re: Railguns vs lasers

        Lasers are ineffective against big targets as they're just light weaponry.

        I think railguns will be better, although at the moment that's only a partly informed guass.

    3. Tom 7 Silver badge

      Re: Railguns vs lasers

      You got a laser that can shoot a ship over the horizon?

  11. casaloco

    When the missile is doing mach 8...

    When the missile is doing mach 8 shooting it with bullets is pointless.

    It has enough kinetic energy to punch through one side of the ship and out the other.

    Unless you hit it with something of greater mass, it's still going to hit you.

    1. Alan Brown Silver badge

      Re: When the missile is doing mach 8...

      "Unless you hit it with something of greater mass, it's still going to hit you."

      1: It can be deflected

      2: At mach 8, if you damage the skin, air friction will do the rest.

      3: If it breaks up, you have a lot of smaller impacts, which the armour can handle.

    2. TDog

      Re: When the missile is doing mach 8...

      Well if you are doing M3 (typical military small calibre bullet) then the closing speed is M11. And neither cares which was going the faster; it's still an M11 collision. About 3.7 kilometres per second at sea level.

      (OK - given 1/2 mv^2 one side has much more initial KE but that means it just has more to expend on the other - again a simplification but the released energy plus a serious shock wave is going to make any fuse, gain, boom system on the missile not only problematical but also somewhat superfluous.)

      1. Baldrickk Silver badge

        Re: When the missile is doing mach 8...

        Minor physics question for you:

        What is the magnitude of the differnce between:

        1) two identical cars each travelling at 30kmph in a head on collision

        2) one of the above cars colliding with a cliff wall

        (the answer is probably smaller than you might think)

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