
Navy tests rail gun - zafka
http://news.yahoo.com/u-navy-test-futuristic-super-fast-gun-sea-202608368--sector.html?vp=1
======
awda
Have they fixed the problem where the gun destroys itself after three shots?
(Edit: downvoters: this is a serious question. This is a (historical?) known
problem with railguns.[0])

[0]:
[https://en.wikipedia.org/wiki/Railgun#Considerations](https://en.wikipedia.org/wiki/Railgun#Considerations)

~~~
HCIdivision17
I'm not sure who would downvote that: the amperage is simply staggering! That,
and the railgun project has been around for years, with the self-destruct
problem being one of the more obvious issues with the idea.

Bludino notes [0] a Popular Mechanics article that quote ls 3MA, with a plan
to go to 6MA!

[0]
[https://news.ycombinator.com/item?id=7553163](https://news.ycombinator.com/item?id=7553163)

~~~
jug6ernaut
The amperage is not the issue(main issue at least).

The way a rail gun works the projectile(or its casing) must make physical and
solid contact with the barrel. This is because the electric current actually
flows through the projectile from one rail to the other rail[1]. This produces
huge amounts of wear on the barrel, making it extremely difficult to maintain
the barrel. Both in form and in being able have the projectiles make solid
contact.

[1]
[http://upload.wikimedia.org/wikipedia/commons/9/9a/Railgun-1...](http://upload.wikimedia.org/wikipedia/commons/9/9a/Railgun-1.svg)

~~~
mrfusion
Why couldn't there be small metallic wheels in the barrel making contact with
the projectile? Wouldn't that prevent wear?

~~~
jug6ernaut
I imagine you could do something like this.

Off the top of my head this would pose a few issues.

1) While the magnetic force must go from one rail to the other, the amount of
electric force is effected by how much of the body is doing the conducting(if
my memory servers me). So while you could use wheels, you would still want the
current to flow through the entire(or large portion) of the projectile
housing(for lack of a better term). This leads to the second issue.

2) Melting. With these huge amperage's there is also huge heat levels. If you
were to conduct this much current through a small point(as would be the case
with a wheel) the heat generated would be even worse. Most likely causing the
wheels/barrings to melt.

Neither of which cant be accounted for, just issues that would have to be
considered.

~~~
malandrew
Many wheels, possibly in the form of many small ball bearings on a rail should
work. Many small cylinders instead of spherical bearings would be better.

Even better would be a highly conductive grease non-flammable grease.

~~~
bradleyland
The bearing idea isn't a solution for a few reasons:

1) Rotating bearings still have internal friction, which will still generate
tremendous heat at these velocities.

2) A lot of the heat being generated here is caused by the flow of electrical
current, which isn't negated by bearings. In fact, it would probably be made
worse, because any spherical contact patch is going to be tiny compared to a
flat surface. The suggestion of using many small bearings would seem to
alleviate this problem, but the smaller you make the bearing, the more fragile
it becomes.

At its heart, this is a materials science problem. You need a material that
can conduct the electricity, withstand the heat, and not break down under high
friction loads while doing both of these. Simply dropping in a bearing doesn't
solve any of these problems

The highly conductive, non-flammable grease is just another materials
challenge. At the kinds of temperatures present in a rail gun, "non-flammable"
becomes a very high bar for a lubricating fluid.

------
JackFr
The first operational beam weapons and rail guns really bring out in stark
contrast that all a modern weapon system is, is the ability to reasonably
safely store potential energy 'here' and accurately release it 'there', with
hopefully catastrophic consequences.

What railguns and beam weapons do, is weaponize nuclear reactors and gas
turbines, reducing the need for propellants and explosives. While it's
unlikely that this will allow the aircraft carrier to regain the place it once
held, it seems likely in the future that massive power generation capability
will become more and more important.

~~~
jug6ernaut
> While it's unlikely that this will allow the aircraft carrier to regain the
> place it once held...

Care to elaborate on this? I was under the impression aircraft carriers were
still our best general purpose military tool? (wartime/peacetime/force
projection/ect)

~~~
macavity23
They're great against a low-tech adversary, but against serious ballistic or
(some) cruise missiles, they're just slowly-moving seaborne apartment blocks.
Good writeup here:

[http://exiledonline.com/the-war-nerd-this-is-how-the-
carrier...](http://exiledonline.com/the-war-nerd-this-is-how-the-carriers-
will-die/)

~~~
csense
This is really informative. You should submit it.

~~~
macavity23
[https://news.ycombinator.com/item?id=547596](https://news.ycombinator.com/item?id=547596)
\- should probably have searched before posting original link :)

------
edgarallenbro
$25,000 for a single projectile is "affordable"?

Why do I feel like I'm living in a madhouse?

~~~
JoeAltmaier
A single-use anti-tank weapon costs $50,000, and worth every penny if you're
the infantryman and the tank is heading toward you. Its dirt cheap at the
cost, considering the price of a tank.

Same for the railgun. They are shooting at million-dollar targets.

~~~
PavlovsCat
Increasing the costs for other tax payers does not make it cheaper though.
Furthermore, the weapons cost the same wether they are fired at an approaching
tank, into the air, at a bunch of baby seals, or not ever. It's not like
weapon peddlers buy back the unused stuff at full price, do they.

~~~
JoeAltmaier
In a better world we'd not need weapons. But give these guys a break: this
weapon is essentially all about the cost-cutting. It replaces million-dollar
missiles, which are definitely single-use. It doesn't need resupplying with
powder - it makes its own propellant (electricity). Each round takes around 1
cu ft, so a single ship can carry hundreds/thousands instead of a dozen.

This is you tax dollars at work, cutting costs for everybody.

~~~
PavlovsCat
That at best makes this the exception to the rule, and is a drop in the ocean.
Yeah, it saves money. Kinda like cleaning a needle makes it more safer to
inject heroin you found on someone who died of bad heroin. Technically, this
is true, if you accept a few premises I personally don't buy into.

Do you really think this changed:

 _The business of buying weapons that takes place in the Pentagon is a corrupt
business - ethically and morally corrupt from top to bottom. The process is
dominated by advocacy, with few, if any, checks and balances. Most people in
power like this system of doing business and do not want it changed._ \--
Colonel James G. Burton

And it also doesn't change the fact that how much value something destroys
doesn't increase the value of it. If anything, it's how much value it protects
that does. There's generally tax payers and demagogues on both sides, fucking
their own populations much harder than their "enemies", and the more value
gets destroyed in that process, the sadder the outcome for humanity. Exactly
because it's all mostly a racket, such a mythos of heroism and adoring the
technical excellency of it has been created, and because it's so shameful,
people defend it so pettily, and uselessly. Like I would care about downvotes
when speaking my conscience.

------
fasteddie31003
As a lover of technology and science fiction I love this railgun. But as a
taxpayer and pragmatist, I really think it is a waste. I can't see this being
as accurate as a guided missile over long ranges, which is the most important
thing for modern combat. So that leaves it as a good alternative for short
range attacks, which I doubt it will ever be used in combat for.

~~~
Retric
Drones don't need pilots which means they don't need pilot training which
changes the economics of air-combat. For around ~100k you can build a long
rang self guided drone which would be almost useless vs an aircraft carrier or
a modern fighter. However, for ~10 billion you can have 100,000 of those
suckers and the US does not have anywhere near that many air to air missiles
and it's not going to take anywhere near 100k of them to takeout an aircraft
carrier.

~~~
JackFr
However, $10 billion is a big number for everyone, including the US and China,
although for them its at least possible. It's 150% of Iran's military budget
and about 80% of North Korea's entire GDP.

~~~
Retric
It's 150% of Iran's military budget in one year. Split that over 10 years and
it's 15% of Iran's budget. Granted there would be maintenance costs and it's
not 100% automated plus you they would need storage even if there taking off
from dirt runways etc. But, they don't exactly need 100,000 to be a solid
threat either.

~~~
bunderbunder
> But, they don't exactly need 100,000 to be a solid threat either.

At least as of October 1967, 1/25000 of that figure would have sufficed.

------
dm2
This is the type of ship that it will be mounted on:
[http://en.wikipedia.org/wiki/Spearhead-
class_Joint_High_Spee...](http://en.wikipedia.org/wiki/Spearhead-
class_Joint_High_Speed_Vessel)

I always assumed it would be put on a Littoral class ship. I'm guessing that
the ship is going to be dedicated to this weapon and that's why it wasn't put
on a carrier or LCS for testing.

How is it going to be powered? Will it have it's own dedicated nuclear reactor
and a huge array of capacitors? I wonder what the time between shots will be.

Here are some nice pictures of the latest version, still amazing that it has
become compact enough for a ship in such a short time.
[http://www.gizmag.com/first-industry-railgun-prototype-
launc...](http://www.gizmag.com/first-industry-railgun-prototype-
launcher/21377/pictures#2)

~~~
icegreentea
They pretty clearly say that its being put on the Spearhead for testing
because it has the space for it. And given all the problems they're having on
the LCSs, I think the last they want to do is is to do testing of experimental
weapons on it.

As for power, the LM2500 in the Aegis Destroyers put out 20MW. They have 4 of
them. This gun puts out 32MJ of muzzle velocity. Assuming 10% efficiency, and
you're at 320MJ per shot. If you ran a dedicated LM2500 per gun, that'll get
you a shot every 16 seconds.

~~~
dm2
The Wikipedia page says the engines are this kind and only produce 9MW:
[http://www.mtu-online.com/mtu/products/engine-
program/diesel...](http://www.mtu-online.com/mtu/products/engine-
program/diesel-engines-and-gas-turbines-for-marine-main-propulsion-
dieselelectric-drives-and-onboard-power-generation/diesel-engines-for-
yachts/detail/product/472/cHash/4ff3806e0fd02da8b2018163b14381d1/)

But I see what you are saying, that seems like plenty, I had always assume
that it would take a huge amount of energy (I know pretty much nothing about
electricity).

------
pistle
These are interesting stories. I find mass publicity of war tech interesting.
This one has been a long time coming as noted by all the "this is old news"
responses.

Who are the intended audiences? What is the intended effect? Warnings to the
competition? Psychological effect on economy-draining military efforts in
places like N.Korea and Iran? PR/Sales efforts to the military funding and
recruitment apparatus?

------
ogig
This kind of progress saddens me. Who is going to be the target of this
weapon? Also think in all the human and material resources involved in
creating this, i can't help thinking how many "good actions" could be done
instead. How many medical supplies, food and clean water could be distributed
with the $$$ used in the development and usage of this.

I'm probably just a naive pacifist, but I think the world would be a better
place if Americans stop producing weapons. Especially of this kind.

I appreciate the amazing science behind the nuclear bomb, drones or railguns,
but i would rather keep it on the scifi parcel and wish the were never created
for real.

Again, I'm probably naive.

~~~
chiph
The military would agree with you. After all, they're the ones with the
greatest chance of getting killed in a conflict.

The problem is the policy makers tend to regard them as the first option (when
they should be the last) for a number of reasons. The first one in my mind is
because the number of senators and congressmen with children in the military
can probably be counted on less than two hands. None of them would publicly
state that they want to see Americans killed in a war, but their actions say
different. Dunbar's Number[0] at work.

The other reason is that the US military is amazingly successful. They've
fought a two-front war, one against the fifth largest army on the planet, and
defeated all opponents. And did it without putting the entire country on a war
footing (conscription, entire industries being converted, and so on). So (from
the politician's view), why not hand the problem over to someone who can get
stuff done?

Lastly - As much as I'd like to believe the world is full of potential
friends, if only we could meet and talk -- the reality is that there are a lot
of people out there who hate us. Many of them because we killed a relative or
friend. But some because we don't live up to their expectations. As weird as
that may be. Consequently, a strong means of national defense is required.

[0]
[http://en.wikipedia.org/wiki/Dunbar's_number](http://en.wikipedia.org/wiki/Dunbar's_number)

------
malandrew
Interestingly this story makes me wonder whether economic consequences even
enter the picture when choosing to engage. I never would have imagined an
admiral asking themselves "Is this worth the cost of a $1.5 million missile?"
I reckon that it would be a binary decision based on threat alone. Are there
any guidelines in the military where the commanding officer is instructed to
perform any sort of cost benefits analysis when making the decision to engage
a hostile?

Would a dramatically lowered cost greatly increase the likelihood that the
navy will be more willing to act as an aggressor?

------
scottmagdalein
I can't imagine the amount of electricity (even just for a split second) it
would take to pull this off.

~~~
zafka
In the ideal case, the math is pretty simple. The kinetic energy in 1/2MV^2 .
(integral from 0 to mach 7) so if you know the weight of the missile...

~~~
lifeisstillgood
weapon that can fire a low-cost, 23-pound (10-kg) projectile at seven times
the speed of sound

340m/s ~ speed of sound so thats 10kg at 2380 m/s (wow!)

5 _2380_ 2380 Joules = 28322000 J

or 28MJ or 28MW if it needs a whole second of power or well the output of
~1/10 second of a mid sized nuclear power station

Yes it needs a lot of power

------
iliis
Can somebody please add a warning that there's an autoplaying video? It's a
bit awkward if your phone suddenly starts talking about guns when your
standing in line in a bank :/

Edit: A video tag would be nice in general for mobile users.

~~~
probably_wrong
Aren't you supposed to turn off your phone while inside a bank?

~~~
iliis
I haven't been in that many banks but I've never been at one that tells you to
turn off cellphones , neither in Europe nor here in Africa...

~~~
probably_wrong
Weird. Mexico, Chicago and Argentina[1] have banned them as a security
measure[2]. I thought it was the same all over the world.

[1]
[https://www.schneier.com/blog/archives/2006/08/bank_bans_cel...](https://www.schneier.com/blog/archives/2006/08/bank_bans_cell.html)

[2]
[http://edition.cnn.com/2010/WORLD/americas/11/18/argentina.c...](http://edition.cnn.com/2010/WORLD/americas/11/18/argentina.cell.phone.ban/index.html)

------
harywilke
i wonder about his statement that not a thing in the sky would survive at hit.
from the video of it punching through the reinforced concrete walls, it seem
that there is very little damage to the wall besides the obvious hole. sort of
like the shaolin monk throwing a needle through glass.
[https://www.youtube.com/watch?v=eW_97D0hLBc](https://www.youtube.com/watch?v=eW_97D0hLBc)
but i'd guess this is more a question of what kind of target they are shooting
at. they present incoming missiles (small and mobile) and something over 100
miles away (big and stationary?).

~~~
JoeAltmaier
Targeting is certainly important and remains to be seen if they're up to it.
But Mach 7 means you only have to get a fix on it, and a rough estimate of its
speed; the missile will arrive in milliseconds and the target won't have moved
very far.

But is there anything in the air that has enough extra parts that it can
survive a 10-inch hole through and through, and destruction of everything in
between? Certainly not any missile.

~~~
arethuza
Mach 7 is 5328mph

100 miles at 5328mph is going to take ~1 minute

~~~
JoeAltmaier
And 1 mile is going to take 1.5 seconds. So yeah not milliseconds, but fast.

~~~
arethuza
An ICBM RV in reentry phase (15K miles an hour) or a Sprint ABM (0 to Mach 10
in 5 seconds) now those are _fast_.

------
havemurci
Would this type of weapon be able to shoot satellites right out of the sky?

~~~
munchbunny
It doesn't take much power to shoot a satellite out of the sky. The hard part
is actually hitting it.

Let's say you're aiming at a GPS satellite in geostationary orbit. According
to Wikipedia
([http://en.wikipedia.org/wiki/Geostationary_orbit](http://en.wikipedia.org/wiki/Geostationary_orbit))
you're trying to hit a target that is 20,000 miles up in the sky moving at
about mach 10, and the target is the size of a car. We don't have the tech for
that kind of dumb-fire accuracy, even if you fire the gun from above the
atmosphere. At 20,000 miles, you would need to reliably place a shot within
slightly less than 1/1000th of an arcsecond.

In order to hit a target under those conditions, you would need a projectile
that can do course corrections on the way to the target. Like a missile.

------
netcraft
I have been hearing about rail guns for years - so its a little surprising to
me that the projectiles still cost 25k and they don't expect them to be on
ships till the end of the decade.

~~~
penguat
I'm quite sure that the 25k price could come down, if they were being
manufactured in bulk. I believe it's mostly an appropriately shaped lump of
metal..?

~~~
fit2rule
The appropriate shaping is what costs so much, I imagine.

------
zerohm
So how is the accuracy?

How many shots will it take you to hit a missile 50 miles away? 100 miles?
Parallel vs perpendicular path?

------
Pxtl
Obvious question: when was the last time a US ship actually shot a big
artillery gun at a target?

~~~
jug6ernaut
Gulf War.

[https://www.youtube.com/watch?v=TTetKxtmI9c](https://www.youtube.com/watch?v=TTetKxtmI9c)

------
clef
A bit like what Babylon 5 called "mass drivers".

~~~
Symmetry
That's how the term "mass driver" was used in Babylon 5, but generally you
talk about mass drivers as coilguns propelling loads that combine a magnetic
component that the coilgun acts on with the actual payload, usually either for
propulsion or transport. In Heinlein's novel _The Moon is a Harsh Mistress_
the mass drivers sending products from the Moon to the Earth were re-purposed
as weapons, which is probably where a lot of people first ran into the idea of
electromagnetic projectile weapons, making it the default term for those some
people use. Of course, to quote Niven "A reaction drive's efficiency as a
weapon is in direct proportion to its efficiency as a drive."

So yes, a railgun is sort of like a mass driver. Except that railguns[1] rely
on current flowing through the projectile between two rails and coilguns[2]
rely on the current flowing through a loop around the projectile. And mass
drivers are a sort of railgun where the projectile isn't a specially designed
bullet but a spaceship or hunt of rock or pretty much anything combined with a
magnetic sabot, where as this fire specially designed projectiles.

[1]
[https://en.wikipedia.org/wiki/Railgun](https://en.wikipedia.org/wiki/Railgun)

[2]
[http://en.wikipedia.org/wiki/Coilgun](http://en.wikipedia.org/wiki/Coilgun)

------
mrottenkolber
Being a radical pacifist I aide: I always wanted real rail guns (too much
quake).

------
hawleyal
There is no one to shoot.

~~~
JimmaDaRustla
There doesn't need to be anyone to shoot - it is there to prevent those who
attempt to be something to be shot at.

Remember, it took one bomb to end WWII.

~~~
qbrass
Two bombs.

------
evli
Metal Gear?

------
fbomb
The BFG is still a better weapon.

------
tmikaeld
I would not be surprised if "the enemy" already have the capability to create
something similar.

~~~
Shivetya
well they certainly can claim such, even present photographic evidence, maybe
even a video. Yet you have to ask, who can verify the claim?

Now defending against such is something that would be interesting, I doubt the
Navy's own laser systems, current or ten years out, would be up to it. Seems
to me the best way to avoid it is not being there. So against fixed targets
this is pretty much a real threat.

~~~
dm2
Why do you doubt the Navy's lasers?
[https://www.youtube.com/watch?v=gMfYUyrKRng](https://www.youtube.com/watch?v=gMfYUyrKRng)

Everything I've heard says that they've been very successful.

------
sjtrny
This is not news. This rail gun tech has been around for years. Here is a
video posted in 2012 which shows the exact same gun:
[http://youtube.com/watch?v=eC2hu9bildA](http://youtube.com/watch?v=eC2hu9bildA)

~~~
yread
Interesting it's exactly the same images. Why is this news?

~~~
sjtrny
I think the US Navy wanted some positive press coverage.

