back to article US Navy achieves '100 mile' hypersonic railgun test shot

The US Navy, continuing its quest for a hypervelocity cannon which might restore the big-gun dreadnought to its lost dominion over the seas, has carried out a new and record-breaking railgun test. This latest trial firing pushed muzzle energy to a blistering 33 megajoules (MJ). The muzzle velocity, as in the previous 10 …


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  1. Paul Williams


    'The ONR wants to achieve lab trials at 64 MJ, potentially offering 200 mile range with projectiles striking at Mach 5, before trying to build an actual weapon.'

    Surely that already *is* an actual weapon? You wouldnt need much of a projectile to make being hit by it at Mach 5 rather annoying, to say the least...

    What are they firing at the moment? Teddy Bears?

    1. Anonymous Coward
      Anonymous Coward


      it is a weapon, but the navy can't exactly call it that when they have to rebuild the thing after every couple of shots. The levels of power running through these things causes the rails to erode from the electrical discharge across tiny gaps.

      comically, several years ago, a physics student built one in his university basement, as a hobby, that far outstripped anything the navy had built up to then.

      1. detritus

        More info, please?

        "comically, several years ago, a physics student built one in his university basement, as a hobby, that far outstripped anything the navy had built up to then".

        I don't suppose you've got a link to this handy, do you? I'm interested to know more! :)

        1. Olafthemighty

          More info, you say?

          You could wander over here: and have a look, for starters.

    2. The First Dave


      I hardly think it counts as a weapon if it is some sort of immovable test bed, presumably somewhere in the Mojave desert. Do you expect "the enemy" to come and visit the one spot in the USA where this is installed, and helpfully stand right in front of the butts?

      1. Anton Ivanov

        It could have counted as a weapon if it was built close enough to shore

        What the navy forgets is that there has not been a single case in the last century and a half where the navy has succeeded in a frontal assault on a fortified coastal artillery.

        The defence of Port Arthur, the disastrous Gallipoli campaign, the defence of the MoonZund in 1917, the defence of Kerch in 1941, and so on. The list can be continued for many pages. In all cases, as long as there was someone to man the coastal batteries and they still had munitions the navy lost. It took bringing land artillery into the equation for the attackers to win.

        While a drednaught can carry a big gun a coastal battery can and will have an even BIGGER GUN. As long as it remains a duel of gun vs gun navy will lose and it will take bringing in airplanes and missiles once more to keep the odds at an equilibrium.

        1. Paul_Murphy

          Yes but...

          A shore-based battery, being a fixed location, can be battered very easily, and hitting a moving object which is over-the-horizon brings it's own problems - manily being locating it well enough to hi it.

          A naval ship, know where it is, and where the batery is, has a much better chance of putting the shore-based battery out of operation I would have thought.

          Out of interest how does mach 7 compare to escape velocity? - oh never mind, escape velocity is around 11km/s and mach 7 is a little over 2k/s - shame, would be an interesting way to put inorganic items into orbit..


          1. Anonymous Coward
            Anonymous Coward

            You don't need escape velocity

            Orbital velocity is lower than escape velocity (which is the velocity you would need to continue into outer space and never return)

            Low-earth orbit is about 7.8km/s, and you get 1.6km/s for free from the rotation of the earth at the equator, so you need an additional 6.2km/s. Mach 7.5 is about 40% of this.

            So making a bigger one of these guns and sticking it on the top of Mount Kilimanjaro would be an interesting project :-)

            1. John Smith 19 Gold badge


              Gun launch comes up on a regular basis and I think there is a usenet FAQ on it.

              Big drawback is the *very* serious friction heating you get.

              There's a very good reason why rockets do *most* of their accelerating above as much of the sensible atmosphere as possible.

              A useful rule of thumb is that atmospheric pressure halves for every doubling of altitude starting at 5600m. At that height you are at about 1/2 standard. This makes a *big* difference on air density which is a key issue for heat calculations. the skins and inlets of hypersonic aircraft (if they *ever* get built) face similar problems.

              Yes it *is* on a par with re-entry heating levels.

            2. John Smith 19 Gold badge


              IRL you need to factor in launch losses. That typically adds c1000 ms and you can write off that 1.6 Kms if you want polar launch (and quite a lot of people would). .

        2. Anonymous Coward


          Hmmm, the interesting thing about the Gallipoli assault was that the British and French Navies had already won. They had defeated and passed all 4 pairs of forts protecting the Dardanelles, and only lost when a Turkish minelayer laid the last of the Turkish supply of mines behind the Allied ships and 6 battleships were lost in the course of a single day. The admiral running the show then lost his bottle - despite over 20 battleships being committed to the attack, and the attack already having been won.

          Also don't forget these were pre-Dreadnaught ships. Used for land bombardment because they were considered obsolete for naval combat.

          Since then we have had the most recent example where the USS Missouri was used to successfully bombard the Kuwaiti coastline in the gulf war.

          The problem with land fortifications is that they are generally immobile. If you have a really big fortress the Navy will generally just dodge around it. The only time this becomes a problem is when the fortress is protected a choke-point like the Dardanelles. But then the Navy has an advantage and it is called concentration of force. If the Army builds a fortress 10 times more powerful than a ship, then the Navy just brings 20 ships. Und so weiter. This is also why the US Navy is currently all powerful. There are plenty of nations which could stand up to 1 Nimitz Class carrier, but if that becomes a problem the US just brings 8!

        3. Marcus Aurelius

          Not sure what you mean

          In Gallipoli, the allied forces lost ships to mines, not guns, the Germans won the 1917 Moonzund encounter against coastal artillery (and Russian vessels). Normandy landing relied on a huge naval bombardment (granted with air support). I'm not sure what you're trying to imply with Kerch as it was heavy losses to both sides. Toulon had its coastal artillery taken out by naval bombardment.

          Its actually a trade off. Coastal artillery has to hit a moving target, whilst the naval artillery has stabilisation issues against a static target. Most of the latter are handled perfectly adequately by computers nowadays....

          1. Anton Ivanov
            Thumb Down

            Germans at Moonzund won by ground

            Germans failed to pass Ezel coastal forts at Moonzun until they were taken from behind. The fleet _FAILED_ until land units broke through to take the pesky coastal artillery out of the equation. This was all despite the fact that it was barely manned by a ragtag demoralised crew on the verge of deserting.

            After that Germans indeed won the naval scarp with the fraction of the Russian fleet facing them. However the time they wasted on Ezel and the scrap with the mine squadrons at Kassar costed them the overall victory as they have expended enough ammunition and fuel to have no choice but to retreat instead of facing the core of the Russian fleet pulling out of Helsinki.

            As far as Gallipoli, if the coastal batteries were such a pushover the mine laying crew would have never ever had the chance to lay those mines.

            As far as modern naval units - from the perspective of a projectile travelling at M7 they are as immobile as a land fort. So as long as the land artillery has means of determining their current location they are dead meat.

        4. John Smith 19 Gold badge

          @Anton Ivanov

          "What the navy forgets is that there has not been a single case in the last century and a half where the navy has succeeded in a frontal assault on a fortified coastal artillery."

          I think that's also a running theme of EE Smiths Lensmen series.

          Planetary defenses beat space based dreadnaughts *every* time.

          1. TeeCee Gold badge

            @John Smith 19

            EE Smith also solved the problem of how you deal with humungous levels of weapon power that burns the beggars out in the Lensman series. Treat the barrels as disposable and fit an autochange system........

            1. John Smith 19 Gold badge
              Thumb Up


              "Treat the barrels as disposable and fit an autochange system........"

              I'd forgotten about that trick.

              Something similar crops up in Barrington Bailey's "The Zen Gun."

          2. Anonymous Coward

            One issue with planetary defences

            They're usually at the bottom of a gravity well, so anything the enemy chuck at them with home in nicely.

            So, if you're not to worried about the planet surviving, just punt astroids at from the other side of the system until it's squished!

            1. Anonymous Coward

              Starship Trooppers cross over

              Asteroids?, You're not one of them damn bugs are you?

            2. John Smith 19 Gold badge


              In the sense of "homing" onto the body itself yes. That's more for killing a whole *planet*.

              As for *precision* strike or the "Rod from God" concept then no you need something a bit smaller and a bit more subtle.

          3. Anonymous Coward
            Anonymous Coward


            So nuking it from orbit isn't the only way to be sure?

        5. SkippyBing

          What the navy forgets

          German invasion of Norway, all kinds of fortified coastal artillery there and they did even manage to sink one German battle cruiser.

          Of course the key point is frontal assault, what kind of moron commits a frontal assault?

  2. Nigel 11
    Thumb Down


    Methinks firing big heavy slugs at aircraft and missiles is not an answer. One would have to hit a very small target with an unguided projectile. At long range - even at Mach 7 - the target will be able to see it coming and dodge. Especially so with something that by definition emits a very large low-frequency electromagnetic pulse when fired. Countermeasure - random automated jink on e-pulse detection. So stick to guided missiles for engaging aircraft at range, and rapid-fire machine-guns at short range.

    Which leaves only ships and stationary targets which might be able to defend themselves against guided missiles and bombs.

    1. LDS Silver badge

      Guided projectiles

      There are already guide projectiles. Although it may not be easy to "steer" something hypersonic. But if used at close range a target may not have enough time to evade a very fast and small projectile.

    2. SkippyBing

      Depends on the range

      A Close In Weapons System (CIWS) like Phalanx or Goalkeeper is only designed to take things out in the final mile or so and they use slugs going at a mere Mach 3. I think upping the velocity to M7 can only help and possibly increase the range, plus if it's attacking you it depends to be coming directly towards you so the firing solution is less tricky.

      Of course for longer ranges you could give the projectiles steering fins and a laser seeker, it still keeps the rounds relatively cheap as most of the guidance equipment is onboard the platform.

      1. Anton Ivanov

        You are missing the point

        Phalanx and other similar systems are designed to kill a missile which is more or less a very thin shell around a fuel tank. It takes a couple of hits at most and it does a nice and pretty BOOM.

        An artillery shell (even one fired by a railgun) is nothing like that. It is _HARD_ and it will make a hell lot of damage even if it will not blow up. At M5+ you do not need a warhead.. Shooting at something like this with Phalanx is an exercise in futility. Same for close-in missile defences which work on a proximity fuse basis. In fact it is same for anything else short of one of those nuclear armed interceptors used in the 1975 USA or (current) Russia missile defence systems.

    3. Vic

      Not sure that's feasible...

      > At long range - even at Mach 7 - the target will be able to see it coming and dodge

      200 miles at Mach 7 is a little over two minutes.

      That's not much time to react to a pulse which you might detect from half a country away, and which might or might not be a railgun, which might or might not be aiming at you...


    4. Caff


      Surely a shotgun type blast from one of those at mach five would pretty much litter the sky with enough junk to take down almost anything

      1. Steve Evans

        Re: buckshot

        Not really... The problem is the smaller the "shot" the less mass each piece has whilst increasing the surface area and air resistance of the load. This means it will slow down pretty quickly compared to a single shell with the same mass of all the combined bits of shot.

        I'd much rather have someone shoot at me with a shotgun at 100 yards than a .22 rifle. The shotgun may have a larger charge, and cover a larger area making me easier to hit, but by the time those little bits of shot reach me (if they haven't just dropped to the floor), they'll be lucky to make it through my coat, let alone my skin. Whereas the .22 slug would really hurt!

        1. Vulch
          Black Helicopters


          Fire a cannister of shot with a bursting charge. Needs to be more accurate than pure shot, but keeps more of its velocity.

          1. detritus


            And, coïncidentally..


          2. Dave Bell

            Old trick

            That's what schrapnel does.

            (The word usually gets applied to any random fragments from an shell, these days.)

        2. <shakes head>

          tell that to my brother

          he was picking pellets out his butt for weeks

    5. MegC



      Mach 7 is 2382.03 metres a second according to google.

      For a bullet at Mach 7 it would take something like 67seconds to go 100 miles... I'm pretty sure planes (even ye olde time sub sonic planes) move fast enough to "not be there" over a minute after you fired?

      Now I'm assuming Mach 7 is the speed it arrives at and that it is most likely fired off at at least twice that? If you cut that time in half to 34 seconds even a mere human could react in time?

      Am I missing something?

      1. jubtastic1

        Re Am I missing something?

        Yes you are.

        It's not designed to take out aircraft 100 miles away, that would be daft for obvious reasons.

        Long range targets would be fixed installations or things that are difficult to significantly move in under a minute, like honking great big ships.

        Local enemy aircraft could be taken out by similar, but scaled down tech, with velocity and projectiles tailored to tearing aircraft or missiles out of the skies, something more akin to metal storm than the cannon in the article.

      2. Anonymous Coward

        Mach is a variable number

        Mach is the speed of sound in Air.

        Air density varies with altitude, humidity, etc.

        So Mach 7 represent a range of number

        Roughly 760 mph at sea level, through to 670 mph at 30,000 feet

        Useful constant if you are a pilot, aircraft designer, or alternatively a civil servant who does not want to be specific about how fast your planes and missiles go.

      3. Anonymous Coward
        Anonymous Coward

        You lead the target, that's how.

        I think the point of these guns is for defense and not offense. If you fire at any moving target, your chances of hitting it are small unless you have built-in guidance. Which you COULD do in this type of projectile. In case you don't have a GPS on board the projectile, you can predict, with limited accuracy to hit a moving target providing it didn't move again.

        Now, say a ship-to-ship missile is fired. It would be pretty easy for a computer to hit that target with nearly 100% accuracy.

    6. The Indomitable Gall

      At mach 7...

      At mach 7, a projectile could be over the horizon within a minute. A plane at cruising altitude directly overhead would have less than 4 seconds to evade, and a pilot would need to be looking towards the gun to see the bullet.

      Your countermeasure relies on detecting an EM pulse several miles away, which means it's going to be too sensitive, and would be triggerable by much smaller devices nearby. In fact, enemy interceptors could be armed with a decoy EM generator to activate enemy countermeasures during dogfighting, throwing the pilot off-line and unable to get a missile lock.

    7. John Smith 19 Gold badge

      @Nigel 11

      The US Navy had a guided artillery shell project using GPS. Note that radar proximity fuses have been fitted to AA shells since WWII. Assuming that things about 10m long (well it look pretty big to me) that gives it a *relatively* leisurely 58g acceleration. The Spring ABM IIRC was pulling 100g+ from launch. I think Sprint holds the record for a lot of this mad stuff.

      1. John Smith 19 Gold badge


        My senior moment.

        Using V^2=u^2 + 2as with m1=340ms^-1 with s = 10m a should be 325125ms^-1 or c33 000 g.

        an interesting way to reduce any thing organic to a puree in almost no time at all.

  3. Anonymous Coward

    The The Meantime, German Researchers on peaceful things like 2liter/100km cars. But nice to see the USN now have a 100km range electric projectile. As long as any capable American works on weapons, China and Germany can proceed to destroy the US economy like a breeze. Weitermachen !

    PS: Admittedly, a small number of German researchers do non-peaceful things, just in case we have a an urgent need to sink an aircraft carrier. But their budget is quite small and they have to think before they build anything.

    1. Thecowking
      Thumb Up

      Point it upwards

      Point the barrel straight up, ramp up the power a little and voila! Instant orbital insertion for small sats. Assuming you can shield them against the actual launcher, job's a good 'un.

      Now Germany can make these great toys too, but for peaceful means. Then, should you need to sink a battleship or destroy a nearby coastline, a simple reorientation of the barrel and there you go!

      Mind you, I suppose you could make a bigger and better launcher by building it into a mountain or something...

      1. Paul_Murphy

        sorry - but no

        Escape velocity is around 11 kilometers a second:

        Mach 7 is somewhat slower:

        Nice idea though.


        1. Thecowking

          @Paul Murphy

          No one said this was the finished product mate.

          Scale it up by building it into a mountain by the equator, use high temp super conducting coils, bit of the old liquid nitrogen, and a 3km long shaft, slap a nuclear power station at the bottom (you'll probably need a lake or sea too, for cooling and whatnot).

          Then you've got something which you can use to give a bloody good boost to your payload, even that might not be enough to get it into orbit however, but you can certainly get it a damn good way up, at which point you'll need less chemical fuel to get it over the edge of the well.

    2. Sir Runcible Spoon


      Didn't you know, America works on weapons so that they can *take* everyone else's toys/money once they have enough of it.

      1. Anonymous Coward
        Anonymous Coward

        @Sir Runcible Spoon

        "...everyone else's toys/money ..."

        You forgot OIL

      2. Anonymous Coward
        Thumb Down

        @Sir Runcible Spoon

        Last time the US tried to fsck with China, McArthur cried for nuclear weapons. All those bombers could not do much against millions of Chinese soldiers firmly dug into the ground.

        Then in Vietnam, the Wacko In Chief was also so desperate he actually ordered B52 dummy runs on the Soviet Union. It was NOT this "mad airforce colonel/boodily fluids" thing. It was Nixon & Kissinger themselves ! In the end, millions of hard-working, hard-fighting, disciplined Vietnamese overcame all the technology throwing more bombs at them than thrown at Germany in WW2.

        Talking of Germany, it was demoralized and bled white by the Red Army, not by US technology.

    3. juice


      It's hardly like this is the only project the US is pouring it's research money into.

      In any case, I wouldn't knock this research too much: as with the space programme, there's significant amounts of potential secondary benefits; aside from the need to develop new materials (including superconductors?) for both the railgun and it's projectiles, they also offer a potentially cost-effective way to get stuff into orbit: build a bigger one so you can ramp down the acceleration curve and you could even get humans into orbit without having to strap them on top of a giant container of highly toxic and dangerously explosive fuel...

      Besides all that, any true sci-fi fans will know that this is a step towards welcoming our 32,000 tonne robotic overlords...

  4. Anonymous Coward
    Anonymous Coward

    recoil ?

    I suspect a type 45 would be in bits after firing one of these a few times.

  5. Graham Marsden

    "this rate of firing would leave little juice left for propulsion"

    So cue the SF cliche of the "Big Weapon" that you dare not use because to do so will leave you dead in the water until your power recharges...!

    1. Tom 13

      Everybody to

      the Third Bridge!

  6. Desk Jockey

    Good god!

    Being hit by one of those things would hurt! Is Lewis proposing to aim a large, several tons worth of railgun in a manner to take out aircraft? I think they had better stick to smaller and faster firing weapons or better still self guiding ones! By the way, lots of aircraft can fire cruise missiles from about 200 miles out, 10 aircraft, say with 2 missiles each? Not good odds for the railgun carrying dreadnought which will be back to using point defence systems.

    Which brings me to range, 200miles on a ship is still not enough. The Chinese strategy for countering US aircraft carriers (well known by everyone) is to fire a lot of short range ballistic missiles. Couple that with the fact that the projectiles will not be explosive (other than just travelling very fast) it makes this technology useless for anything other than taking out other ships. Other ships of which can fire their own cruise missiles or send out helicopters or stay outside of 200 miles and scream for aircraft or submarines to do the job for them.

    A huge railgun firing ship sounds scary, but the weapon is likely to take up the whole ship, won't be hugely effective and so it will need to be defended by other ships, best of all by an aircraft carrier which.... can do everything it can and more! Now a submarine fitted with this system that just requires it to surface, fire and duck back down again would be useful, but seawater and electricity? Hmmm, fried sailors!

    1. Eric Crippen


      I don't think that there would be anything resembling a nervous system, much less a stain, to feel the pain. The shockwave would probably spray you four sheets to the wind (I don't think I got this phrase correct).

      1. asdf

        hmm not sure about 4

        but 3 sheets to the wind is what they say about most Scots by about 10pm on the weekends.

    2. Anonymous Coward
      Anonymous Coward


      Fried sailors or seamen stains?

    3. YARR
      Thumb Up

      Why surface at all?

      Better still, why not design it so the sub doesn't have to surface to fire the railgun? All that's needed is for the tip of the railgun to break the surface of the water for a second while it fires.

      1. Vic

        Not a great idea...

        > All that's needed is for the tip of the railgun to break the surface of

        > the water for a second while it fires.

        Something similar was tried with the M1. The idea was to surface, bang out a shell or two, then submerge again.

        Trouble is, getting the barrel open at the right time always seemed to be a problem. Most firings of that gun took the end of the barrel off...


  7. Steve 13


    I was just wondering about the time taken to cover 200 miles at mach 5. Turns out it's about 3.15 seconds.

    Assuming that it's fired accurately in the first place, I doubt that a 3 second warning, even with automation is sufficient for any naval target to move significantly.

    I'd hazard a guess that even with computerisation it's actually pretty difficult to land your mach 5 slug in a space the size of an aircraft carrier though, so I guess like the gun battles of old, multiple shots would be exchanged (assuming the target is capable of returning fire at 200 miles range).

    As an anti aircraft or missile system, presumably a variant firing many much smaller projectiles would be developed. At closer ranges (ie within a couple of miles) even a high G missile couldn't avoid being hit.

    1. Steve X


      Mach 5 (at sea level) is pretty much exactly one mile per second.

    2. Tim Parker

      @Steve 13

      "I was just wondering about the time taken to cover 200 miles at mach 5. Turns out it's about 3.15 seconds."

      Unless i'm musch missteakin - 3.15 seconds at Mach 5 would get you about 17,500 feet at sea level on an average-ish hyper-sonic projectile flinging day. That's about 3 Nautical miles which, though quite a fair distance, is a tad shy of 200 miles (Statute or otherwise)

    3. Stoneshop Silver badge

      You're way off

      Speed of sound is 340m/s, roughly. Mach 5 is 1700m/s, a bit over a mile per second. Now explain how you can cover 200 miles in 3.15 seconds at that speed.

    4. Personne

      Maths fail

      If you cover 200 miles in a bit more than 3 seconds, you're travelling at almost 200 * (60/3) = 4,000 miles a minute = 240,000 miles an hour, which would make Mach 1 about 48,000 miles an hour, rather than the more commonly quoted figure of 768 mph.

    5. Tim

      Might want to check your sums

      It's over 2 minutes, assuming sea level mach number and constant velocity for the entire flight which it won't be.

      To cover 200 miles in 3.15 seconds you'd need to be travelling at nearly Mach 300. Again, sea level.

  8. CaptainHook


    Wouldn't a project moving so fast have an extremely flat trajectory, how do you hit anything just below the horizon?

    Or is the projectile going to be guided?

    If so, then you need electronics and actuators which can with stand reliably being accelerated from 0 to 7.5 Mach in the lenght of the rail (based on the video about 10 meters at most). The G-Force would be insane.

    1. lglethal Silver badge

      Someones forgotten their basic physics lessons

      If you launch something with a trajectory on Earth, even at hypersonic speeds, gravity still provides a 9.8m/s^2 downwards acceleration (downwards being towards the centre of the Earth naturally). Hence you will get a standard parabolic arc, as you do with any weapon.

      Bullets fired from a gun follow the same path (only at much slower velocity), so your right that the object will APPEAR to have a very flat trajectory, but will indeed be following a parabola back towards the Earth... It might just take around 100 miles to do it...

      Only problem i see is if your trying to hit something thats behind a mountain...

      1. Paul RND*1000

        Behind a mountain

        Wonder how many of these projectiles it would take to literally move mountains?

      2. CaptainHook

        There is still a dead spot

        Imagine an Artillery target, just the other side of a steep hill. The guns can send shells which either hit the hill, or fly too high and the shell ends up miles down range, in either case the target is unaffected.

        The flatter the trajectory, the bigger that dead spot behind that hill that a ballistic flight profile can't hit.

        A railgun has a very flat trajectory because of the speed of the projectile, therefore although it will come back down to earth I don't think it could drop fast enough to hit a target just beyond the horizon, the curve of the earth is acting like the hill in my Artillery example. Either the projectile hits the water before it hits the target or it flys harmlessly overhead and splashes down miles (and miles and miles) down range.

        I suppose you could vary the power output of the railgun so that the velocity of the projectile allows it to drop faster, i.e. less power the closer the target is but that means less energy delivered to the target.

        I suppose that targets just beyond the horizon could be dealt with using missiles but that kind of defeats the point of a railgun battleship to start with since you now have to load the battleship with explosive, large expensive ammo which is what Railguns are meant to avoid.

        I still think the projectiles would need active guidance to be useful, i.e. they aren't just following ballastic flight paths, and that means they need electronics and actuators capable of being acceralated from 0 to 2800m/s in the space of 10 meters.

        1. Anonymous Coward


          "I don't think it could drop fast enough to hit a target just beyond the horizon"

          The Horizon isn't a point at which land suddenly starts to drop away, it's due to the curvature of the earths surface and is relative to the location and altitude of the observer (affected by any intermediate surface deformations like hills and mountains).

          Given that the horizon is relative to the observer, anything just over the horizon will very rapidly be closer than the horizon relative to the projectile once it has left the muzzle (assuming a fairly flat landscape).

          1. CaptainHook

            I know horizon isn't just a sudden drop

            My concern was that the trajectory would be so flat in the early stages of the flight path that the curvature of the earth would be greater than the drop of the projectile resulting in an area which couldn't be hit. However, I've now done some spreadsheet calculations.

            At Mach 7.5, after the first second of flight, assuming a completely flat firing angle, the earths curvature means the surface would be 35 cm lower but the projectile would would have dropped by nearly 10 meters. So this thing wouldn't have a flat enough trajectory to cause a problem.

            My bad.

  9. Popup

    Escape velocity

    Mach 7.5 corresponds to about 2.5km/s, which is about 20% of the escape velocity. Methinks NASA ought to be investigating this as a method for launching satellites...

    1. Sir Runcible Spoon


      "launching satellites"

      really? how many satellites do you know of that could withstand that kind of G?

    2. Miek

      a tit is required

      25Kms and you can kiss the grass goodbye.

    3. Anonymous Coward


      Hear hear. The ideal usage would be to use the railgun to give the initial thrust to get the payload moving, then fire rockets to actually get to orbit. From what I can recall, rocket engines are really inefficient at getting something moving from a dead stop, especially since most of what they're lifting is the weight of their propulsion.

    4. lglethal Silver badge

      Sorry theres a fair bit to go....

      In order to get a working mass driver/rail gun orbital launch facility you need to have an ejection velocity of ~20km/s.

      Current studies suggest that ~3km/s is the maximum ejection velocity you can achieve due to power losses and heat (hence why i suspect that the navy are keeping there gun at Mach 7.5 and just upping the payload being launched).

      So whilst i would love this sort of tech to be used at the moment its nowhere near getting us into space. I suppose the best current solution using this tech would be to use the rail gun launch as the first stage in a multistage rocket. However, firing a highly explosive rocket from a highly electric, high heat rail gun seems like it could be a slightly dangerous (explosive/suicidal) operation...

  10. Anonymous Coward
    Anonymous Coward

    A cloud of deadly Teddy Bears! - your kids wouldnt sleep unless there was a monster under the bed!

    Does anyone else feel that this technology could be far better used by putting objects into orbit?

    And by 'objects' I dont mean warheads! Would be far better than using rockets to get large parts off the ground!

  11. nigel 15

    More impressive than world record breaking...

    ...ballistic weapon is....

    the panning camera shot. which must have been taken by clark kent.

    1. Jon 63
      Thumb Up

      Glad im not the only one...

      ...who noticed this, anyone who has tried any type of sports photography or filming knows tracking targets is very hard work - even when you have foreknowledge and leadin (think sitting oncomong to a car which then turns a corner infront of you) so following this projectile out of a tunnel is mind bogglgingly awesome (and obviously baed on timing math/laser traps and very telescopic lenses!)

      Tracking that projectile at those speeds is a feat of acomplishment as big as getting this thing to fire

      On to the weapon!

      A little math:

      200miles = 321,868.8meters / mach7 = 2 382.03m/s = 2:15 travel time until impact

      (assumptions for constant velocity projectile not final impact velocity)

      If you solve for mass, you get a projectile weighing 11kg(ish), thats one hell of a punch (same assumptions used)

      Interesting point about trajectory and firing over the horizon given this things speed, distances etc if you fired at a 200 miles target your bullet would drop 1,324.35m's (again assumptions made on shape/wind/etc)

      Sadly I've run out of mathtime(and ability) to work out how far "up" from the origional point of firing this would make your projectile reletive to sealevel but its certainly an interesting problem to a firing solution at other seafairing or ground based targets!

      This thing would be fun to play with if it weren't for the rebuild requirements! Wonder if we reach lasers with this type of energy level which would be easier to use. it'd be an interesting game of cat and mouse if you can shoot over the horizon with a railgun, but obviously out of line of sight for a laser? - Rock Paper Railgun, Lasers, Spock anyone?

    2. Anonymous Coward

      Bet the cameraman drinks...

      ...Carling Black Label

  12. Anonymous Coward
    Anonymous Coward


    I wonder whether the electromagnetic radiation produced by switching all that current would interfere with the ship's radar and telecommunications.

    1. Steve Evans

      Re: Interference

      That's the least of their worries, have they not seen the Philadelphia Experiment?!

  13. Anonymous Bastard
    Thumb Up

    Velocitas Eradico

    Did you notice the logo at the end of the vid?

    1. Tim

      Good spot

      I think that's the motto of my local safety camera partnership.

  14. Brian Miller 1

    Turbo Boost

    Aim all railguns directly behind us.....

    Fire on my command.


    150 NAUTS SIR!!! She cannae take it captain.

    Just a little more Scotty.

    Tha's as much as I can gi ya cappin.

    Very well, Uhura, see me in my quarters.

  15. Anonymous Coward
    Anonymous Coward


    I'm curious as to how ballistics would affect this type of weapon, for a long range target I would guess that active projectile guidance would work, but what happens when you shoot at a target just far enough away to be below the horizon, but close enough that the ballistic curve is shallow enough (at mach 7) so that it flies over the top. (you wouldn't be able to depress the elevation enough without hitting the surface).

    1. Gotno iShit Wantno iShit


      Say you fire a projectile horizontally 10m above sea level. It will accelerate downwards at 9.8m/sec^2 due to gravity. There is a precise speed the projectile can travel in order to remain at exactly 10m above sea level with the curvature of the earth compensating for the fall due to gravity. Lets call this speed X. If the projectile is fired below X it will always end up wet, if it is fired above X you have a blind spot over the horizon. The correct name of speed X is Escape Velocity and as others have said mach 7 is well under that.

    2. Charles 9

      That's assuming you take the low road.

      However, in naval gunnery, the preferred method is to take the high road. Reason being you have a chance at hitting one of the less-armored parts of a ship: the deck. That's why dive bombers packed such a punch during WW2: not only were they delivering bombs from beyond terminal velocity, but they were targeting a pretty vulnerable part of the ship.

      Given assistance from an AWACS, computers should be able to provide a targeting solution that takes a higher arc, allowing them to nail a target even at just beyond the horizon.

  16. Brian Miller 1

    Sattelites? Building materials more like.

    The G's pulled in reaching escape velocity would pertty much rule out a lot of manufactured goods. However sending raw materials into space for assembly after reaching orbit is a good shot. I'm talking rolls of sheet metal, girders/framework. PV panels, Screws and Fixings, etc.

    It means that only sensitive materials would need the expensive launcher based mode of transport.

    Eventually if we get enough machinery up there they could start pulling in NEO's for material and processing them up there. No more energy would be required to reach escape velocity, and space ventures might actually become an energy SOURCE rather than a SINK.

    Heres to dreams...

    1. Baskitcaise
      Thumb Up

      B&Q home delivery?

      "However sending raw materials into space for assembly after reaching orbit is a good shot. I'm talking rolls of sheet metal, girders/framework. PV panels, Screws and Fixings, etc."

      So if there is a malfunction and the power is not enough for orbit at least the houses that will be demolished by the stuff coming back will have the tools and supplies needed to repair the damage.

    2. annodomini2


      The materials would vaporise due to air heating, because of the velocities involved.

  17. M7S

    Flyboys won't lose their superiority for long, if at all.

    Once they get "orbital", then they're still higher up in the gravity well.

    Or that X-37B could start to seed the skies with lots of things pointing downwards in readiness. One shot railguns perhaps. Treat as mines with range.

  18. Liam 8


    NASA are already looking at this as a space launch system but it would probably never see the light of day. The reason why this can both only use inert slugs and it is less than ideal for satellites is that the acceleration is not entirely conducive to sensitive electronics. A human would be reduced to warm jelly, electronics would be turned to scrap.

  19. Daedalus


    33 MJ is about the energy of a few litres of petrol. Or a few kg of solid rocket fuel. A missile launched from the ship could have the same range and better guidance. It's not as if these slugs will be any old piece of iron. They'll be expensive specialized ammunition. This is a system in search of a purpose.

    1. Anonymous Coward
      Black Helicopters

      Actually, we've got the purpose,

      just not the rail gun. This is only a first generation gun and we'll need another 7 generations before we've got the weapon we want.

      Well, that and a few other odds and ends that aren't really worth mentioning.

    2. annodomini2

      ah but...

      If you have a ship that is nuclear powered, which I think is the main aim of this thing.

      Then you only have to store ammunition, which contain no explosives and are much smaller, so you can store much more of them in a given volume and they don't need special handling requirements or protection.

      Also if it was so simple where are the hypersonic missles?

  20. call me scruffy
    Thumb Up


    The crucial issue here is bombarment.

    There isn't much you can do about an inert supersonic balistic projectile once it's in flight. One of these could shell whitehall from 200 miles away, and the best you could do would be to evacuate.

    CIWS works by disrupting a projectile that would otherwise explode on impact, and which might just fall to pieces once intercepted. Anti Ballistic Missiles work by nackering the guidance systems of incoming warheads, or just vapourising the warhead, so that it doesn't detonate. Neither of these countermeasure techniques will work against a simple solid lump of depleted uranium.

    Say you want to take out a runway on the Falkland islands, one of these could do that before most navies could even tell that you were there. And even if ships don't go for station keeping, one of these could take out an entire harboured fleet in a few minutes.

    As for generating power... we could take a leaf out of the German U boat book, and mount one of these on a nuclear sub. Surface, Shell, Submerge in ten minutes?

    (Now I've got an idea about a 4.5 incher fitted into a trident launch tube;-)

    1. Anonymous Coward

      @call me scruffy: Oh Really ?

      I'll launch either a S-400 with a 100kg Uranium warhead or a Mad Cowboy Navy Rocket (SM-3) with 50kg Uranium at it. Let's see what your 17kgs of Mach-8 Uranium will do.

      I'll leave the verification of the 17kgs to you. And the performance of the S-400, probably the most powerful supersonic tactical missile in existence.

      1. Charles 9

        That's a lot of missiles you're firing.

        In terms of the maths, the delivery system in this case (the missile) is the more-expensive consumable in your equation. And for a multi-shot bombardment, that's going to add up the war costs. OTOH, once you have the railgun in place, the projectiles aren't exactly much more expensive than your warheads (at worst, you'll probably be using up some relatively-cheap sabots). Given enough juice, you could launch a bunch of them for much less cost than using a bunch of missiles. Not only that, the projectiles could be made quicker since they're simpler.

        1. Anonymous Coward

          @Charles 9

          Your Electric Dreadnought will be hit by my widly-and-randomly-up-and-down-left-right jumping S-400 after firing three rounds. Game Over.

          The S-400 I can launch from a submarine, a stealthy fast attack boat or a slightly reworked A340 with a decent ELINT package and a search radar. I just peek over the horizon at 600kms distance, acquire your Dreadnought, go down to 3kms height, close in to 300kms distance and launch the S-400. When it hits, it is at Mach 12.

      2. SkippyBing

        Hypersonic Interception

        Is extraordinarily difficult*, assuming the rail gun becomes suitably weaponised, it should be relatively easy to saturate your defences with multiple rounds in a short period of time. I'm also not sure why you're using inert uranium warheads on weapons systems that aren't designed for them. SM-3 and I believe S-400 aren't designed to necessarily hit the incoming target, just get close enough for the explosion of the warhead to rip it to shreds.

        *The difficulty increases by an order of magnitude for every Mach number you go up.

  21. Anonymous Coward

    title goes here

    ".. recharge it for another shot in a little over a second and a half, though this rate of firing would leave little juice left for propulsion"

    cba to do the sums, but wouldn't the recoil keep the matelots chugging away quite nicely? Perhaps not a good idea to fire uphill or sideways though ...

  22. Neil Stansbury

    Not a launch vehicle

    This can't be used as satellite launch vehicle, this is still a gun - the G forces exerted on the projectile over such a short barrel distance are enormous, and would easily crunch delicate satellite bits.

    Now... constrain the projectile in a donut shaped barrel, taking multiple cycles to bring it up to launch speed before ejecting it, then you might have something useful for flinging stuff other than HE shells....

    1. Paul_Murphy

      Now THATS a thought.

      Why limit it to A projectile?

      Have a circular 'particle* accelerator' which holds, say, 50 particles in constant motion - when the moment is opportune a suitable number get diverted to the final accelerator 'turret' where they get directed to the intended recipient.

      Hmm - make the whole thing nuclear carrier sized and shaped and you will have the best of all worlds

      Speak quietly and carry a large number of hyper-mach sticks.


      *for our purposes the particle will be around, I don't know, 2Kg or so?

  23. Alfred

    Escape velocity

    Escape velocity is somewhere around Mach 30, depending on where you launch from, and of course that assumes no forces other than weight acting on the object (i.e. zero air-resistance). We're not quite there yet, but this is an impressive step towards it.

  24. This post has been deleted by its author

  25. bofh80

    Good to see

    That american scientists still have little or no idea how to use the tesla tech they are sitting on. Maybe one day they can share what they have classified (hmm wikileaks could do it mebe jaja). And the rest of the world could explain to them how it works. Before they blow themselves up with it.

    “C = E/R”

    Maybe one day.

  26. Anonymous Coward
    Thumb Down

    Sloppy journalism

    "The new Royal Navy Type 45 destroyers, the first warship class to use electric transmission for main full-speed propulsion"

    Captain class frigate were used by the Royal from 1943 to 1956, these ships were powered by electric motors with the power for generators coming from either diesel engines or turbines

    1. Dave Bell

      And also...

      USS Lexington (CV-2) for one.

      Also one of the ships Robert A. Heinlein served on.

  27. Steve Evans


    If this thing is accelerated by electromagnetism, where does all that smoke some from? It doesn't look much different from a standard chemically propelled shot in that respect.

    1. Personne

      Re: smoke

      The rails burning?

  28. Vulch

    There are two types of warships

    Submarines and targets.

    Just sneak your AIP sub ( into range, no need for your own electro-dreadnought.

    1. Anonymous Coward

      @Vulch: Type 212 With S-400 Maybe ?

      The Eurosub Type 214 of Kokums/Thyssen-Krupp with an S-400 motor and a IR & Radar sensor would fly 400kms at Mach 12. You can put high-speed CPUs into it, as it only accelerates with 100g.

      If that doesn't work I am sure Krupp-Atlas Elektronik has a nice, very silent torpedo, which could lie on the ground for a year until the a/c carrier comes along and wakes it up from a healthy sleep :-)

  29. bitten

    Paris Gun

    Given the small size of the shell it will probably not better the Paris Gun (1918) and its 1600m/s for long range shooting (130 km).

    1. Anonymous Coward
      Paris Hilton

      Paris Gun

      130km and 1600 m/s? Now I see why she's OK with a 2-stroke. 4 would smart...

  30. Jake Rialto 1

    What about one of these!

    The only way to deal with a railgun dreadnought – just as in the days of old when the first armoured all-big-gun battlewagons appeared – would be by using a ship just like it. Surface warships and surface-fleet officers, once again, would rule the seas and the naval roost.

    Or one of those sub surface thingies that I heard about in Sci-Fi books.......Submarines. That's them!

    Have they been invented yet?

  31. Craig 28

    Only way to deal with a railgun dreadnought is another ship the same?

    Leaving aside the possibility of long range missiles, fired either from air or surface, there is also the little issue of submarines. These ships are just as vulnerable and would be prime targets, so they would still need heavy protection. That's why aircraft carriers ride round in the middle of a big bunch of ships. That's assuming indeed that an anti air variant can be developed as well.

    If these truly came into service militaries would simply counter them with extra long range missiles fired from land or ships, or if these can be reliably intercepted even when fired in large numbers plain old subs firing torpedoes which can't be intercepted. Hell, how about a long range cruise torpedo? Give it topographical maps of the sea bed combined with narrowly-focused sonar purely for looking at the sea bed and avoiding running into underwater hills, give it the location of the target and let it turn on its full active seeking sonar when it is in the target zone to look for whatever you want it to sink.

  32. Anonymous Coward

    Kalte Dusche: Facts


    - the acceleration in that 10meters long launcher is horrible:


    horatio@horatio-rotating-in-grave:~$ echo "scale=10;(8*300)^2/(2*10)"|bc


    so thats:

    echo "scale=10;(8*300)^2/(2*10)/9.81"|bc


    times the earth's acceleration.

    Other ships have plenty of warning to turn their rusty high-speed cannons (only Lewis' Navy still uses them) and put at least 500 slugs into the precisely calculable trajectory of the Mach 8 thing. Other navies launch ESSM for the thing. Yeah, the computer might need to be sped up, but the mechanics is more than capable to hit the Mach 8 electrothing.

    What you say ? Random movements ? Good luck with making thrusters& electronics which withstand 28000 times the earth's acceleration.

    Non-cocktail party officers of Nelson knew that F=m*a. A valve weighing just 10grams must withstand 280kg of "normal" weight.

    What would an educated Weapons Officer use ?

    Something like this:

    It will put 500 kg TNT next to your hull - an energy of about 500kg*6Mj==3000MJ. Have fun to detect it so that you can point the rusty cannons or ESSM.

    But who said the Lewis Navy had the educational qualities of Horatio's Navy ?

    1. ElReg!comments!Pierre

      Countermeasures? You're kidding, Shirley.

      "Other ships have plenty of warning to turn their rusty high-speed cannons (only Lewis' Navy still uses them) and put at least 500 slugs into the precisely calculable trajectory of the Mach 8 thing. Other navies launch ESSM for the thing. Yeah, the computer might need to be sped up, but the mechanics is more than capable to hit the Mach 8 electrothing."

      Assuming you could detect the thing (how do you detect a passive 10 kg lump of uranium going mach 6, again?), you would need to observe it for quite a while in order to predict a trajectory. And even if you were able to do that, you'd need a very fast and accurate cannon to hit it even once (it's considerably smaller than a guided missile). And even if you had a cannon fast and accurate enough, what do you think you would achieve by putting a few slugs in a solid block of uranium?

      So in short:

      - you won't even see it coming at all

      - even if you saw it coming you couldn't calculate a trajectory fast enough to act on it

      - even if you could your cannon (or ESSM) probably won't be able to hit it.

      - hitting it won't do you any good, if it was going to hit you, it will still hit you. And you're still dead.

      The only possible counter-measure is not being near the impact point when it hits. Planes and missiles might have a sporting chance if they can detect the thing early enough (not easy) but anything slower is toast.

      1. Anonymous Coward

        @pierre: Ever heard of millimeter wave Radar ? Plasma ? IR ?

        A certain European nation does have a radar system capable of things which are much more impressive than looking at a 17kg lump of metal 100kms away, surrounded by a plasma which certainly is electrically conductive and will reflect HF waves. Plus, being Very Visible on IR when the weather is good.

        The problem of shooting down this slug is no more complex than shooting down a ballistic warheard or a satellite, because these tend to be even faster. France, China, Russia and the US already have this capability and if Germany were on a war footing we would have it too.

        An incoming S-400 in ship-killing mode is much, much more dangerous because it's thrust-vectoring system can be commanded by a computer which executes an cryptographically hard PRNG. Also, the terminal speed of the S-400 is Mach 12 (12*300m/s == 3600m/s)

        The Mad Cowboy Navy should better team up with Curtis LeMay's Men Of The Apocalypse and develop this airborne laser thing into an S-400 interceptor. The SM-3 of the MCNavy is basically a less capable version of the S-400.

      2. Anonymous Coward

        Just to be clear... @ ElReg!comments!Pierre

        "- you won't even see it coming at all"

        Seeing it coming is easy. Most modern militaries these days have millimetric radar that they use for counter battery (you detect a barrage and fire your own counter-battery artillery at the location is came from). You get to see a very small high explosive very early. The faster it goes the easier it is to see as well since you can use simple computer algorithms to filter out everything that is small but going too slowly (birds for example).

        "- even if you saw it coming you couldn't calculate a trajectory fast enough to act on it"

        You only need to see a very small part of the trajectory to predict the rest. Thanks Newton! That is how point defence systems currently work. Don't forget mach 5-10 isn't an impossible speed - especially when in a ballistic trajectory. If you are detecting it 10 miles away you have about 10 seconds to respond. The real likelihood is that with a powerful enough millimetric radar you will be able to see it about 30 miles away.

        "- even if you could your cannon (or ESSM) probably won't be able to hit it."

        Hitting it is going to be hard, but not impossible. The advantage of modern point defence systems is that they shoot lots of rounds (3000-4000 a minute) and the radar tracks the outgoing rounds as well as the incoming. That way the computer can self correct an initial miss and retarget things. When you are a mile or so out, that only takes a second or so.

        "- hitting it won't do you any good, if it was going to hit you, it will still hit you. And you're still dead."

        This is a bigger issue. The best you can probably hope for is to distort the aerodynamics of the projectile and either cause it to topple, or slow down. Unfortunately, both things are likely at those sort of speeds to have minimal effect on final target point. The boffins will have to get to work here, but maybe you can do something with high explosive rounds? The key thing is to either introduce enough energy in to the system to get a marginal course correction, or screw up the aerodynamics enough that the thing topples.

        What will likely work a lot better is simple defensive maneuvres. With a good millimetric radar you should be able to pick up the projectile and predict impact point about 30 miles out. Giving you 20-30 seconds to change your position. That might sound difficult with a large warship, but your requirement is only for the ship to be in a different location to where it was expected to be in 20-30 seconds time. Even a crash stop would probably be sufficient to screw up the fire control solution. Unless you are either steering the rounds (very hard), or more likely self correcting with your own fire control radar and pumping rounds out one every second or so, a hard ship hit will be hard. Then it gets into spotting the rounds far enough away and that just means putting your millimetric radar on an aircraft and spotting them 200 miles out. This may prove useful for land bombardment, but sea-skimming guided missiles will likely be a lot more useful for ship to ship engagements for a long time to come.

        1. Anonymous Coward

          @Believers: Just Launch S-400, SM-3, ASTER or ESSM

          ESSM is the smallest of the listed counter-missiles, yet it weighs more than 250kgs. So it is ten times more heavy than the Mach-8 e-slug.

          My prediction is that ESSM hitting the e-slug will simply result in a vapor cloud. But certainly it would make sense to dust off a Pershing-1 or a Scud and lob that e-slug warhead against an ESSM to see what really happens.

          If ESSEM is equipped with a uranium warhead of similar size the result is quite predictable - vapor.

          1. SkippyBing

            ESSM is a MISSile

            Not a HITile, it's not designed to necessarily hit the target, just get close and go boom which is easier and to date provides a reasonable chance of hard kill. Also the ESSM is significantly less dense than the slug, so you'd have to make sure a nice hard bit hit it or it'd probably just punch straight through and carry on its way.

            Phalanx may or may not help, bearing in mind even against something like Sunburn the best it's thought possible to achieve is converting a missile at Mach 2 into lots of shrapnel at Mach 2, the final destination doesn't really change much.

            I would be interested to know what putting that much energy into the water near a ship was likely to do though, that may be more than sufficient to achieve a mission kill without having to actually hit the target.

            1. Anonymous Coward

              @SkippyBing: SM-3 Is Also A "Missile"

              But they managed to hit a satellite Head-On. I am not an expert on the ESSM, but with a precisely known trajectory, I do think it is feasible to perform hit-to-kill with an ESSM.

              As I said, it must be tried with a Scud or Pershing lobbing 15kgs of Uranium at an ESSM. The problems are more likely related to software. If the Uranium slug is too hard, simply put Uranium on top of ESSM. And launch three ESSM, spaced with 0.5 seconds to that at least one of them will be a direct hit.

    2. Jellied Eel Silver badge

      Don't forget we're broke!

      KEPD 350, yours for 1m euros a pop. USN's SLAM-ER, $750k a pop. Ol'faithful, the Harpoon, $1.2m a pop or Tomahawks at $600k. All slower and so potentially easier to intercept.

      Then platform limits. Refitted Iowas, 32x Tomahawks and 16x Harpoons. Arleigh Burkes, 96 missiles. Can be tricky to reload missiles at sea as well. So limited ammo and rather expensive in terms of initial cost and ongoing O&M for complex weapon systems. But the defence contractors like that.

      Railgun, potentially cheaper O&M, cheaper ammo and more of it, which may come in useful if there's a need to do land attacks. Dumb, fast slug harder to intercept and destroy. Sounds like fun to me assuming they can overcome design challenges like energy storage, rail erosion and not EMP'ng the ship every shot.

    3. c0rruptd
      Thumb Up

      Why fire one?

      I haven't actually heard anyone yet mention that last little tid-bit where with a substantial power plant, a dreadnought could pump out 15 rounds a second... A Phalanx CIWS can only fire 5 times that rate, with 20mm shells. Couldn't the dreadnought just saturate the target area with Mach 7 slugs, so that even if most of them are somehow turned aside, your still looking at an awful lot of high-velocity metal punching holes in your ship (and anything else that happens to be nearby).

      Ahhh, the pitter-patter of hypersonic uranium rending shipping into twisted metallic Swiss cheese... =P

      1. Anonymous Coward
        Thumb Down

        @c0rruptd: That will work for One Second

        ..then your 15 launchers will need to be cooled for one minute. And your dreadnought is more precisely a "converted supertanker".

        I' ll have plenty of time to launch 15 ASTERs, because it will take at least 50 seconds until the 15 projectiles hit.

        1. SkippyBing

          Cooling for a minute

          Says who, there's a lot of water around for cooling and it's not like the world's navies don't have experience of ripple fire to maintain a continuous barrage.

          Also it could take less than 50 seconds for the projectiles to hit if you move closer to the target, very few weapons are fired at max range, you wait for the pk* to be a sensible value like 0.7. Plus you've just used 15 Aster missiles which is a large proportion of the magazine stocks of any missile carrying warship, another couple of salvos and you're empty. Never mind the issue of deconflicting 15 missiles that are all aiming for roughly the same space.

          The massive advantage this system has is you can store lots of cheap inert projectiles onboard and saturate any defenses. Sure some of the rounds may get taken out by some mythical SM-3 or S-400 that actually performs according to the manufacturers specs and trials, but you only need a couple of hits to ruin the enemies day.

          *pk - Kill Potential, old avaition saying 'The ground has a pk of 1'

        2. c0rruptd


          @Schlamperei Ist Teuer: I would love to see the cost difference between 15 ASTERs and 15 railgun slugs. Thats not to forget SkippyBing's point about magazine capacity (and volatility, I'd rather be sitting on a magazine full of inert metal slugs than a magazine packed with rocket fuel and high explosives)...

  33. DS 1

    dark skies

    Although the US may pioneer this, there is a very dark cloud to the silver lining. You can call this the dark skies lining. That being that within a handful of years (or less if they are unlucky) - this tech will become universal. And with its universal nature, its going to render all current naval power open to question, but in particular large scale naval sitting duck power. By that I would say US nuclear powered target tugs - ahem, I mean Carriers.

    Third world idiots could build or redesign a freighter with a big fat rail gun, and they would only have to get close enough to succeed. And at any silly distance (lets say 10 miles for the sake of argument) at 0.67 Miles per second a Carrier has only seconds to live. And if the aim and calc is right, would not even know what hit them.

    The day a US carrier gets hit, is the day US carrier operations draw down. 200 Miles at mach 7 with a carrier sinking ability? Game over man, Game over.

    Nothing exists that can stop a mach 7 200 mile range ship killer. Nothing. Course, it doesn't yet exist, but thats clearly only time limited.

    1. Anonymous Coward

      @DS 1: The Sky Is Already Very Dark: S-400, Mach 12

      Mind you, the S-400 is a thrust-vectoring missle and just needs to withstand 100gs. Just put in an infrared seeker and the right algorithm. Then mount on a Kirov Class cruiser. Oh, they already did that. Sorry.

  34. Anonymous Coward

    You can't hit what you can't see

    Lots of chatter about shooting things 200 miles away with ballistic projectiles.

    The main limit on a surface warship is what it can see, the curveature of the earth makes that roughly 20 miles for one our £1bn floating coffins.

    Big gun 20 mile battleships circa 1915 to 1935 could see what they are shooting at. a modern surface ship with no airborn radar can't see 200 miles.

    Modern surface combat could probably best be described as hide and seak play by eggs armed with sledge hammers, with a blind fold if you have no over the horizion capability..

    I would also be interested in how accurate the thing is at 100 miles.

    A modern service rifle can kill at 5km, but I know only a very few people that can hit a man sized target at 800m.

    1. Graham Marsden

      @You can't hit what you can't see

      So you launch a spotter aircraft or drone or you use satellites to locate your targets...

      1. Anonymous Coward

        Re:@You can't hit what you can't see

        optical sats dont work through cloud cover, trying to keep one over your ship would burn all the thruster mass, spotting 1 aircraft in couple of thousand square miles of ocean would be impressive. (think trying to find 1 light aircraft in SW USA recently)

        The RN has no AEW drones, plans or budgets for, even if they could be retrofitted to our already costs £1bn/hull ships (although this is a good idea, which is why it will never be funded, just the same as the RAF want air launched drones to give pilots a better idea of whats up ahead)

        AEW Seakings are currently limited to large helo carriers

        Spotter planes (ala RNAS 1916) need a carrier

        1. SkippyBing

          AEW Seakings are currently limited to large helo carriers

          Not really, they can operate of anything that can take a Sea King, which includes T-45, Tankers and T-23. Although they tend to prefer the RFAs tankers as the accomodation is nicer...

          As for there being less AEW aircraft than ships, yes but that's not a problem because in an ongoing war type situation the ships like to be close enough together that they can provide mutual support with some doing the ASW thing, some doing the AAW thing and both doing a bit of ASuW. Handily you should be able to get quite a few under the radar footprint of a Sea King ASAC.

          1. Anonymous Coward
            Thumb Down

            AEW Seakings are currently limited to large helo carriers

            two words - HANGAR SPACE

            1 on station, 1 going on station, 1 in maint, Oh!, that 1 more than we have hanger space for on a T45, and that assumes you only want to extend your coverage in one place, and oh yes, you've now lost the ASW helo. so now your a dead target for all the sub types

            If you want to fly AEW Seaking on a solo warship, you need 4 medium helo hangar slots, like HMS Tiger used to have. (even this sacrifices ASW capability)

            We are still designing WW2 destroyers with some modern toys, as opposed to a self contained combat ecosystem in a suitable hull. Frankly RFA Argus (a converted container ship) with a well thought out helo compliment would beat the crap out of any £1bn T45 in a one on one engagement.

            If you figure 5 slots for AEW, 5 Slots for ASW, you need a stable hull with at least 10 medium helo hangar slots. These days we call those carriers.

            1. SkippyBing

              Two Words

              Task group, you can probably figure the rest out, but you don't need a carrier with the task group to maintain AEW coverage, RFA Fort Victoria can take 3 without any hassle, as well as refuel and supply the other ships. And if you don't want all your eggs in one basket mix it up a bit around the group.

              Unless the 849 Flight I saw on her in '03 was some sort of optical illusion.

              If you think there's going to be some sort of battle involving Mach 7 rounds being flung about without ships being formed up in a SAG then I'd like to hear how you'd deploy them?

              1. Anonymous Coward

                Task groups vs Real Life

                To quote TE Lawrence, With 2000 years of military history we have very few excuses for mistakes

                The RN would obviously not wish to operate a task group without the appropriate set of complimentary ships, even when it was the largest navy in the world, such as in 1942, when Force Z got ripped apart by aircraft, because thier aircraft carrier had run aground earlier, and the replacement couldn't catch up. Cost 2 capital ships and the lives of over 800 RN sailors.

                The example above was picked because it was one of the rare occassion of the UK military actually planning for the right thing, even if the demon murphy did strike afterwards and inflict real life on the plan.

                With a "on station" navy today of barely more than 10 hulls (factoring maint, transit, etc.), the chances of having a task group in place when it hits the fan is next to non-existant. Hence the RN should be deploying hulls that are self contained, i.e. do not have to rely on mythical outside support.

                Personally I think the next warship the RN loses, will be sat out on it's own, with only it's own resources for the captain to call on, probably doing embargo enforcement for the UN, when the country in question gets pissed off (look at Korea for recent template example)

                Today the only ships that can project power, and defend themselves are carier type hulls (inc RFA hulls). Hence the navy should stop wasting money on £1bn versions of WW2 designs, and actualy design ships for the 21st century based on modern comiment practice, preferable before we add another 200 sailors to the list of service personel killed by their own brass's stupidity and political game playing

    2. Charles 9

      Five letters--AWACS.

      Noting like an eye in the sky to give you a view over your sea-level horizon.

      1. Anonymous Coward
        Anonymous Coward


        AWACS is a great way of looking for things

        If you have the available airframes

        if they are not tasked elsewhere

        if they can reach and operate in the target area (i.e. how many in transit to have one on station)

        if you can adequately protect a self illuminating traget that big and slow (i.e. having fighters available for escort)

        also RN Hulls - AWACS = number of uncovered RN Hulls

        1. Anonymous Coward

          Mount EriEye On A330MRTT

          Or better: Let BAE/Thales integrate a phased-array-radar in the body side of the A330MRTT tankers. Uplink the radar data to a sat which will broadcast it down to the Type45.

          Type45 will launch ASTER-30 based on the cues from the A330MRTT radar. Type 45 will also launch Storm Shadow SLCMs to attack land targets and large ships.

  35. Anonymous Coward

    To Be Fair To The Lewis Navy

    ..they are indeed planning to use stealthy cruise missiles:

    In the Type45s, Lewis claims to be "air-defence" only. It seems an illegal grand-grand-grand-grandson of horatio managed to sneek into whitehall and do some good work. I am sure his rank is not more than that of a lieutenant.

    For admiral you need to know all the cocktails and how to make 'em. "whiskey please, so I can do the licking for the special relationship".

  36. Graham Bartlett

    Why fixate on hitting a plane at 200 miles?

    Of course you can't do that very easily. But at maybe 10 miles out with a Mach 5 cloud of fragmenting projectile it'll be a pretty reliable hit, and that's the kind of range you want for missile defence. If planes can't kill you, that leaves either subs (torpedos) or artillery bombardment (you can't easily stop a shell in flight). If you've got your Magic Railgun Shield over a convoy, you can protect a bunch of ASW boats and helicopters. And if you've got a range of 200 miles, you can hit damn near anything without being in range yourself.

  37. Anonymous Coward

    Why fixate on hitting a plane at 200 miles?

    Because it works. S-400 of the Almaz Design Bureau.

    1. SkippyBing

      Yeah but

      a) Does it, I mean have they function tested it? And what's the minimum altitude it can detect aircraft at at 200 miles?

      b) Can you mount S-400 on a ship?

      c) Who says the CONOPS for the anti-air rail gun is taking things out at 200 miles, which is a capability of limited use in most modern conflicts where issues of friendly fire and IFF raise their heads?

      1. Anonymous Coward

        @Yeah but

        Look up "Kirov Class" on wikipedia. It has at least S-300, which is nearly as capable as the S-400. Now that the Russkies have enough money, I am sure the upgrade is already on-going.

        Looking behind the horizon certainly is a major issue, but that could be done with a superlarge helo like the Mi26 carrying something like EriEye.

        The Mi26 can only climb 5kms (a bit better than the Seaking), so it is not as good as a fixed-wing AEW a/c, but still much better than a shipborne radar.

        Note that the S-300 is not the Kirov's intended surface attack option. They have some really nasty and heavy, supersonic missiles on board.

        Still, it would only be a software upgrade to use the S-300/S-400 in a surface attack role. The SM (1,2,3) missiles have always been dual-roled, why should it not work for the S-400 ? I guess the russians want to poke a bigger hole than a S-400 or SM-3 can make. So that the first hit is also a sink.

        In addition to that, they might have one or the other joker like an equivalent to GlobalHawk or a satellite-based radar system (which they apparently already had in soviet times) to provide over-the-horizon targeting data.

        1. SkippyBing


          You're playing imaginary Soviet Technology Wikipedia Top Trumps again aren't you.

          The imaginary bit being where it works and the launcher tubes aren't sealed shut with layers of paint. Or your insistence on putting EriEye on anything that flies, although why you chose the Mi-26 is beyond me when the Russians already have Helix to that very job with a Russian radar they can presumably data link to.

          And you still don't seem that clued up on how military tech and tactics actually work rather than your Tom Clancy version of it.

          Oh yeah, anything on successful test firings of S-400 or are you just going with what the brochure tells you?

          1. Anonymous Coward


            If you kindly look at the videos on youtube regarding the S-300 and S-400 you might be convinced that it works very well. I do not know their numbers deployed, but I am sure they have at least one working battery of S-400 and many S-300 batteries.

            See this, written by a someone (a "raven") who is "in the know":


            Historically, Soviet SAMs have been very effective, when properly used. Soviet-made SAMs shot down many US planes during the Vietnam war and would have denied airspace to the U.S. if they had not worked hard to attack their electronics. The half-mad "Wild Weasel" tactics were developed to tackle these SAM sites.


            The American peer SM-3 is also very capable and it has exactly the surface-attack mode I described.

            Regarding the AEW system, the Helix could fulfil that role, but is certainly not perfect because of size and endurance. The larger an AEW Radar, the better the potential angular resolution (a very basic physical principle). The Mi26 would certainly be better suited.

            Don't tell me the Russians are incapable of making something like EriEye. They are now awash of oil/gas/ore money and aware that they need a credible defence against the little Tyrants propped up by America.

            1. SkippyBing


              Yes there are videos on youtube of successful Russian weapons launches, however have you actually seen what condition they're in on the front line?

              Regarding the AEW system it isn't a case of 'the Helix could fulfil that role' it is fulfilling that role. Look up the Ka-31, it's even on your favourite source of intel - Wikipedia. Presumably they used that rather than Halo so they could fit it on the ship.

              And stop banging on about EriEye there are lots of radars and the Russians have developed several that are more useful than EriEye because the scanner rotates so you don't spend your whole time looking one way. If you can't even name an alternative that the Russians are using it does imply your google skills are weak young man.

  38. Mike Moyle

    Secondary effects

    I'm assuming that a 200-mile shot would be arched slightly, thus a certain amount of the energy/velocity lost on the up-slope would be recovered on the down-slope. Might also benefit from lower atmospheric resistance at the mid-course for added distance.

    The other issue with a flat launch could be collateral damage -- what sort of pressure is produced by a Mach-five-ish sonic boom generated at or near ground-level?

  39. James Grant

    since the sinking of the Bismarck, really...

    As a nit pick, I'd say it has been since the sinking of the Bismarck (hobbled by an air-dropped torpedo) that planes have been seen to rule the seas.

  40. Alan Brown Silver badge


    How many shots can you get off before you have to replace the barrel? 2? (Just like that death ray 747 really...)

    Very few shots fired by current warships are an inert lump of iron by the way - at the very least they tend to be fused HE+shrapnel charges.

    OTOH: Railguns can be tuned to generate "tolerable" acceleration over longer distances (perhaps 1-2km instead of 10 metres) and if you're going for orbital capability you don't have to rely on the thing to get orbital velocity, just partway there (the faster your payload is going, the smaller its propellent load can be - saturnV stacks burned a large percentage of the first stage fuel just gettiing clear of the tower.)

    I suspect this is like lasers - as much as the miltary want to make a death ray out of it, the things resolutely refuse to play ball.

    Regarding acceleration: There are already guns which can fire projectiles to 120miles altitude and they've been used to put instrumentation up that high on ballistic flights. The hassle is they're more finicky to fire than sounding rockets such as the late lamented Skylark (neighbours don't like loud bangs, etc)

  41. John Smith 19 Gold badge

    Distribution A:Approved for unlimted distribution

    Distribution B available on Wikileaks shortly.

  42. Anonymous Coward

    The REAL danger is this in ASM mode

    Your only hope is that the Russian programmer had a bad day and didn't turn on the Random Jumping Feature in the software he released to her navy. Because your nice little SM-3 warhead will simply jump into the wrong direction trying to intercept the "drunken S-400".

    Drunken Bears - don't pick a fight with them.

  43. Argus Tuft

    but what happens

    if the ship reaches 88 mph?

  44. AndrewG

    Maybe not such a good thing

    Even a Mach 5 shell isn't goign to hit a missle or plane thats manourveing at anything more than point blank range. The SM2's and their ilk work so well becasue they are actively guided to the target

    Also...I'm reminded of the reaction after HMS Dreadnought was built. I recall a comment was Prior to Dreadnaught England had 3 times the number of 1st line ships than any other navy. After Dreadnought it had 1 more 1st line ship than every other navy.

  45. DS 1


    Yes, the chatter is abour 200 miles. But thats just chatter. The real point is that its not that hard to see a rail gun assembly and a chunky power supply being made. And the vessel would only have to get within low range (lets say 10 miles) to clobber a fleet.

    Beyond this fitting some form of flight control and guidance onto said projectile is not so hard. The amount of adjustmet required over 200 miles would be minimal. But thats level2. Just the level 1 base dumb projectile would be potent if within a relative short range of anything like carriers.

    I'm not sure in thread that its been fully understood - but even if the object is relatively small, at mach 7 strike on an object - the damage ensuing is astonishing.

  46. Anonymous Coward
    Anonymous Coward

    Accuracy is the fly in the ointment

    As a few others have pointed out, if these railguns can't hit their targets at 100 miles everything else is moot. I don't care how fast they shoot, any unguided projectile weapon is going to obey the laws of ballistics - and will also be subject to wind deflection and, for all I know, Coriolis force. Back in WW2 battleships mostly duelled at 7-10, and had a hell of a job to score hits. The world record is still held, AFAIK, by HMS Warspite which scored a direct hit on the Italian flagship Giulio Cesare at slightly over 26,000 yards (about 13 nautical miles, or nearly 15 of the landlubber's variety). That took enormous skill (Warspite was well known as the best shooter in the fleet) and a large slice of luck. Now imagine trying to pull off the same trick at 7 or 8 times the range!

  47. Anonymous Coward

    ...reminds me of

    ...Mac Rounds have been authorized.

    Mac Rounds?! In atmosphere?!

    That's one way to get their attention. Hang on to your teeth people!

    (Mine's the one with the XBox controller in the pocket...)

  48. This post has been deleted by its author

    1. Geezer

      Check your dimensions

      kilograms, mate.

    2. Anonymous Coward

      @lewton: Standard SI Unit of Weight Is kg !

      echo "scale=10;2*33000000/(340*7)^2" |bc


      1. This post has been deleted by its author

  49. bugalugs

    Thirty second alert on a 45 Class at 30 knots. 500 feet long, 8100 ton loaded.

    Assuming instantaneous reaction, 40 MW of power perfectly transmitted " FULL ASTERN " would slow the destroyer at about 1.65 foot/sec/sec* , leaving about 450 feet of target. This is serious.

    *envelope math

    1. Anonymous Coward
      Thumb Down

      @bugalugs: Simply Make A Turn

      At least frigates are quite manoeuvrable and could simply perform the tightest turn to the left of right. And fire a lot of CIWS rounds in the meantime. Modern navies would fire ESSM, certainly.

  50. Anonymous Coward
    Anonymous Coward

    Kinetic energy

    Just in case nobody else can be bothered to work it out: kinetic energy = 1/2 mv^2

    with v = 7.5 * 343 m/s

    and E = 33000000 J

    then this is a 10kg projectile. Ouch!

  51. Anonymous Coward

    Fighting the E-slug with CIWS

    According to

    each CIWS slug weighs 0,1kg and has a velocity of Mach 3. If you have ~150 hits into the e-slug, the same amount of material has been sent into the counter-direction. It will certainly degrade the e-slug into something much less dangerous.

    The nice thing is that the e-slug has a quite predictable trajectory, if you have observed a significant part of the trajectory with a suitable radar. So you know very well in advance where the e-slug will be at which time. Plenty of time to elevate/azimute the CIWS cannon and launch rounds exactly in the right moment. You can even fire a few test rounds to determine the wind vectors/profile (and use that to correct your CIWS slugs later).

    Something you don't know with a thrust-vectored missile like the S-400 incoming. It can be programmed to jump in the x-z directions in a highly unpredictable manner. CIWS bullets will simply miss the S-400 because even at Mach 3 it takes one second to traverse a single kilometer. ESSM has a semi-active seeker which can even lock on the attacking projectiles radar seeker or alternatively correct the course via the ESSM radar. I am sure there exist ESSM versions with an IR seeker or a combined ESM/radar/IR seeker.

    1. SkippyBing

      Oh well

      If it's according to wikipedia it must be right....

      Of course with the e-slug coming in at M7.0 you're not going to be able to get 150 rounds off before it's hit you, the effective range isn't big enough.

      1. Anonymous Coward

        @Oh well

        For 150 CIWS slugs I need 2 seconds.

        The terminal speed of the e-slug is said to be 5 Mach. This means 5*340m/s==1700m/s. So I need at least 2s*1700m/s==3400m+ 50m, if 50m is the height of the last slug hitting.

        This is well in the range of CIWS slugs, even though the first 50 slugs won't be very fast on impact. But that is not really necessary, as the relative impact speed will still be Mach5 (because the e-slug is fast).

        Agreed ?

        1. SkippyBing


          I don't agree with your max range for Phalanx.

          Also knowing something about what Phalanx is designed to do currently, you're a bit optimistic if you think every slug is going to the same point in space. The idea is to create a wall of lead the incoming object flies through, which for a missile or aircraft is all that's needed.

  52. basa48

    Action = reaction

    1st law of physics = for every action, there is an equal and opposite reaction.

    Let's get hundreds of rail guns at some point on the earths equator all firing in an easterly direction all at once and the reaction would reverse the earths rotation and we all get younger each year!!!!

    1. Charles 9

      Not 1st, 3rd.

      The first law says objects will maintain their state of stillness or motion as long as they're not acted upon.

      What you want is the third law, which specifies reactions.

      Oh, and just to fill in the gap, the second law describes the relationship of acceleration to mass and force (IOW, just what happens when an object IS acted upon).

  53. ShaggyDoggy

    Escape velocity

    Are you saying that even though I can pop an object 200 miles up in a couple of minutes, it will fall back down because it's not going fast enough ?

    1. Anonymous Coward

      @Escape Velocity

      I'll tell you how to calculate it on your own:

      1. Remove Windows and Install ubuntu

      2.) go to

      3.) go to

      4.) enter

      echo "scale=10;sqrt(9.81*6300000)" |bc

      into the Ubuntu bash shell.

      which gives


      That means close to the earth' surface (less than 1000km height), you need a velocity of about 7800meters per second to keep your satellite orbiting for at least a couple of orbits.


      echo "scale=10;sqrt(9.81*6300000)/340" |bc



      which is the corresponding Mach number. So they have managed about 30% of the required Mach number with the electro-slug-thrower.

  54. Anonymous Coward

    Standard Missile 3, Arrows, S-400, ASTER-30, Storm Shadow, AGM-129

    If you want to rationally analyze the usefulness of rail guns, look at existing, proven missiles and cruise missiles.

    My assessment is that ballistic, "stupid" warheads are useless because they are detectable and cannot maneuver to evade even CIWS (at 50 rounds/second it has plenty time to pump slugs into the "stupid" attacker). ESSM, ASTER-15/30 and SM-2/3 can engage "stupid" projectiles at distances of 10 to 100 kms.

    Hit-to-kill is a proven technology. The fact that not all guided missile designers have dove a good job does not invalidate the fact that others have achieved reliable hit-to-kill against "stupid" projectiles.

    Also, SM-3 and S-400 are up to 50% faster in their terminal speed than the e-slug.

    1. GeorgeTuk

      But above mentioned are expensive...

      ...imagine if you could do similar damage with a cheap projectile.

      Or even better remove the boost stage of a missile fire the projectile and use some fuel to accurately finish the job.

  55. Steve 13
    Thumb Up

    dropped a decimal

    It's 3.15 minutes, not seconds, my mistake.

    Whoever voted the post down could have just posted a correction instead though!

    You do have to wonder if you could hit a moving target with that sort of delay though. Even assuming 100% accuracy, they only have to change course or speed by a small amount in that 3 minute window and you'll miss by a good margin.

  56. Anonymous Coward

    Orbital And Escape Velocities

    In general, if you want a satellite with mass ms to orbit an object with mass m at radius r, you need to overcome the gravitational force Fg.


    with G=6.6*10^-11

    You overcome this force by the Centripetal Force Fc from rotating at a radius r with speed v:


    This means Fg = Fc

    from which follows

    ms*v^2/r = ms*m*G/r^2

    which is

    v^2 = m*G/r

    This is the general formula as discovered by that educated Englishman Newton (who also tried to keep the Casino under control then, only to be poisoned by mercury). It is valid for any distance.

    so if we plug in

    mEarth = 5.9*10^24kg

    and orbit 150 kms abobe the surface of the earth (r=6300km+150km) we get

    v=sqrt(m*G/r)=sqrt(5.9*10^24kg*6.6*10^-11 Nm^2/kg^2/6450*10^3)

    $ echo "scale=20;sqrt(5.9*10^24*6.6*10^-11/(6450000))" |bc

    7769.94807082105368902512 (meters/s)

    For 5000 kms we need

    echo "scale=20;sqrt(5.9*10^24*6.6*10^-11/((6300+5000)*1000))" |bc

    5870.27912378537946450721 (meters/s)

    Now that's the orbital velocity, but not the launch velocity.

    For that, calculate

    LaunchEnergy = OrbitalEnergy, which is

    LaunchEnergy = OrbitalKineticEnergy +OrbitalPotentialEnergy, which is

    1/2*ms*vLaunch^2 = 1/2*ms*vOrbital^2 + INTEGRAL(h,h0,h1,Fg(h))

    1/2*ms*vLaunch^2 = 1/2*ms*vOrbital^2 + INTEGRAL(h,h0,h1,ms*m*G/h^2)

    INTEGRAL(h,h0,h1,ms*m*G/h^2) is

    W(h1,h0) = ms*m*G/h0-ms*m*G/h1


    1/2*ms*vLaunch^2 = 1/2*ms*vOrbital^2 + ms*m*G/h0-ms*m*G/h1

    that is

    vLaunch^2 = vOrbital^2 +2*m*G(1/h0-1/h1)

    = m*G/h1 +2*m*G(1/h0-1/h1)



    vLaunch = sqrt(m*G(2/h0-1/h1))

    if we plug in the earths mass and a railgun supposed to lift something into 400 kms orbit we get:

    echo "scale=20;sqrt(5.9*10^24*6.6*10^-11*(2/6300000-1/6700000))" |bc


    so we need

    echo "scale=20;8093/340" |bc


    Mach Numbers for that.

    Btw. "Mach" stems from Ernst Mach:

    1. John Smith 19 Gold badge

      @Schlamperei Ist Teuer

      People do keep coming back to this one. It *looks* so simple all it should take is a *little* bit of work.

      Like solid fuel boosters. So little to go wrong. Yeah right.

      BTW while the orbital velocity (depending on *exact* orbital height. I normally go with 7950ms) it totally ignores the atmospheric drag and other losses. The US rule of thumb was a real launcher takes 30k fps or 9144ms. If you need more for the planned payload you've gone wrong and if you don't need all of it you declare a higher payload.

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