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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 MJ …

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Odd...

'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?

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Anonymous Coward

technically

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.

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untitled

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?

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Boffin

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! :)

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Flame

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.

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More info, you say?

You could wander over here: http://www.hightech-edge.com/diy-rail-gun-homebrew-weapon-ravi-gaddipati/5103/ and have a look, for starters.

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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..

ttfn

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Grenade

Gallipoli?

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!

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Grenade

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....

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Happy

@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.

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Happy

@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........

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Grenade

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!

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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.

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Happy

Starship Trooppers cross over

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

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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 :-)

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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?

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Anonymous Coward

hmm

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

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Boffin

AC@13:14

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.

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@TeeCee

"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."

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Happy

AC@10:57

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.

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Boffin

AC@13:14

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). .

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Guidance?

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.

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LDS
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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.

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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.

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Vic
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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...

Vic.

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buckshot

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

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Unhappy

erm?

Erm...

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?

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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.

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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!

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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.

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Black Helicopters

Cannister

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

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Grenade

'XRG-25'?

And, coïncidentally..

http://www.theregister.co.uk/2010/12/10/xm_25_2014_timeline/

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Flame

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.

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Headmaster

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.

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Boffin

@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.

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tell that to my brother

he was picking pellets out his butt for weeks

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Old trick

That's what schrapnel does.

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

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Unhappy

Oops

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.

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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.

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Go

The The Meantime, German Researchers

..work 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.

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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...

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Joke

Sir

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

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Terminator

Duck!

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...

http://en.wikipedia.org/wiki/Bolo_(tank)

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Anonymous Coward

@Sir Runcible Spoon

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

You forgot OIL

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sorry - but no

Escape velocity is around 11 kilometers a second:

http://wiki.answers.com/Q/What_is_Earth%27s_escape_velocity

Mach 7 is somewhat slower:

http://wiki.answers.com/Q/What_speed_is_mach_7

Nice idea though.

ttfn

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@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.

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@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.

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Anonymous Coward

recoil ?

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

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Coat

"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...!

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Everybody to

the Third Bridge!

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