Navy tests rail gun
news.yahoo.com
news.yahoo.com
Bludino notes [0] a Popular Mechanics article that quote ls 3MA, with a plan to go to 6MA!
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...
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.
Even better would be a highly conductive grease non-flammable grease.
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.
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.
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)
http://exiledonline.com/the-war-nerd-this-is-how-the-carrier...
(both for the Millennium Challenge wargames and as a general equalizer of sea power)
The very first thing I thought after all that waxing poetic about destroying a $2M missile with a $20,000 slug was, "OK, now what happens if the enemy launches a couple missiles at the same time?"
And heck, while we're at it you probably don't need such sophisticated guidance equipment if you aren't perching all your eggs on top of one rocket. . . so can this thing achieve a high enough rate of fire to put even a tiny little dent in a large salvo of cheap missiles?
Why do I feel like I'm living in a madhouse?
Same for the railgun. They are shooting at million-dollar targets.
To bad it isn't cheaper we could give every infantryman two! In all seriousness though if you are an infantryman in a Malaria infested swamp anti-malarial drugs are worth every penny too but the production of those are subject to competition so luckily they only cost pennies a pill and every soldier can have as many as needed. The missile's value to a soldier is not a justification for it's cost and if anything the high cost of something like that is detrimental because if it really is that great it means that not everyone can have one.
And the price of an infantryman.
Missles and shells are expensive mostly because they have to propel themselves, but they benefit from the fact that that propulsion system only has to work one time. A useful railgun will need to be able to fire thousands of times without major maintenance before you'll start seeing any cost benefit to cheap ammunition.
This is you tax dollars at work, cutting costs for everybody.
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.
Also all the comments saying that this is cheap compared to some other US weapon that is probably similarly overpriced are just silly. These sorts of things are not subject to the kind of competition that normal goods are. Just look at the cost of space flight for companies like SpaceX and Virgin Galactic compared to NASA's which relied on defense contractors until SpaceX came along.
http://www.reuters.com/article/2013/09/27/us-turkey-china-de...
Its definitely not just a chunk of barstock milled to a point.
25k for a hunk of metal does seem like a very strange price, perhaps there's something more exotic to it than meets the eye?
Expenses for Exploration and Production (i.e. upstream oil & gas) operate on similar orders of magnitude.
At least as of October 1967, 1/25000 of that figure would have sufficed.
That is true, however the US also possesses a large number of anti-aircraft guns, with plenty of bullets. :-)
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...
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.
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).
If the ship can't provide enough power, they'll probably just put some diesel generators in the cargo area.
I assume as testing progresses, it will end up on other types of ship.
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?
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.
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.
A great book on this is "The Better Angles of Our Nature: Why Violence has Declined" by Stephen Pinker. I recommend any pacifist (really anyone) read this book.
While we hear about the immense destructive power of new weapons, the reality is that they are seldom used. Most of our Defense budget is building an army that no one would dare attack. It is like our nuclear bomb policy -- 100% guaranteed retaliatory strike(s) but no first strike. This project is designed to replace expensive missiles with (relatively) inexpensive inert metal slugs that yield the same capabilities (range, stopping power, etc). This is most definitely a program that would lower costs and increase discretionary funding outside of the military.
Would a dramatically lowered cost greatly increase the likelihood that the navy will be more willing to act as an aggressor?
Mach 7 is 2382 m/s. 23 pounds is 10.4 kg.
Since k=mv^2: (1/2) * (10.4 kg) * (2382 m/s)^2 = 29504404 Joules.
That's 29.5 MJ, which is 29.5 megawatt-seconds. So it could mean 29.5 megawatts for one second, except of course the rail time is much less than one second. But who cares, let's convert to household units! 29500 kilowatt-seconds is 8.2 kWh. At an average price of US$0.13/kWh, that comes to just $1 worth of electricity to fire a $25000 projectile.
Oh, yeah, the losses. Those are probably 90% or so, so let's say $10. And mark it up a factor of ten because the electricity is on a boat, so $100, and a factor of 50 because it's a weapons system. So ballpark $5000 in electricity TCO to fire the $25000 projectile.
There's something incredibly shocking about something exploding without traditional explosive chemistry. Just a monumental arc flash (or something - I don't know if it's the same mechanism).
340m/s ~ speed of sound so thats 10kg at 2380 m/s (wow!)
523802380 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
Edit: A video tag would be nice in general for mobile users.
[1] https://www.schneier.com/blog/archives/2006/08/bank_bans_cel...
[2] http://edition.cnn.com/2010/WORLD/americas/11/18/argentina.c...
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.
100 miles at 5328mph is going to take ~1 minute
Let's say you're aiming at a GPS satellite in geostationary orbit. According to Wikipedia (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.
It's a lot cheaper than the alternatives.
How many shots will it take you to hit a missile 50 miles away? 100 miles? Parallel vs perpendicular path?
And boy has the US Military fired a lot of missiles.
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.
Remember, it took one bomb to end WWII.
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.
Everything I've heard says that they've been very successful.