Navy Experimental Rail Gun to Fire GPS-Guided Projectiles

I guess I don't see the true purpose of this. when we have missiles the can go hundreds and hundreds of thousands of miles what do we need a magnetic railgun. I guess I may be uneducated about it. could somebody please explain to me why is this such a big deal when we have bigger things in our arsenal that can do greater damage. is it a radar thing?

Missiles can be detected and shot down by weapons such as the Phalanx CIWS and are dangerous to be carrying around in case of attack. By using railguns that use no explosives they have no risk of the munitions detonating in an attack. And the shells for the railguns are probably far cheaper.

That's great news, missiles weigh a lot, and are storage problems if you can reduce that storage down to 30 pounds and increase the impact speed of the projectile to deliver it on target then you have a devastating weapon. It's a small one but a very useful one, and as the rail guns get more capable then they can be used as a first stage to orbit of microsatellites.

Now a nuclear powered aircraft carrier could easily provide the energy. The energy would be stored in supercapacitors and the energy would be released at one time so even though it is a great amount of energy it can be built up and stored for hours before being used.

Ron Bennett

@ author,

This statement is incorrect, "Electromagnetic rail guns use powerful magnets lined up in series along the length of a cannon". That you described is a "coil gun".

A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. (Wikipedia). Also see "Homopolar motor"

Please check your facts more carefully.

@jonny5ive

Rubiconnn & Ron Bennett covered pretty much all the points FOR having an Railgun

But imho the most important point is Cost-Per-Shot.

A projectile that's damn near impossible to stop, insanely accurate, very long range and with very high kinetic energy (read: KA-BLUM!) can be duplicated by any number of complex munitions (e.g. Missiles, JDAMs ferried by fuel slurping jets and the like)

But one that can be done on the cheap of this scale is something that ONLY a railgun can bring to the table.

Why do wars cost the US so damn much? Part of (a LARGE part of actually) the reason is because the US has a penchant for hurling ALOT of VERY expensive pieces of single use munitions at guys with ak-47s (ok gross oversimplification, but you get my drift) huddled in a cave in the middle of the desert.

To illustrate this point I shall paint you a hypothetical and and super simplified 'gamer' type picture.

To win XX war, you must do 100,000 dmg to enemy

You have:

Tomahawk Missile
Cost per shot: $569,000 (Lowest end version)
Dmg per shot: 1000

JDAMs fired by F-22
Cost per shot: $27,000 (Not including cost of F-22 and fuel)
Dmg per shot: 300

Railgun
Cost per shot: $900 (Estimated cost of projectile and power)
Dmg per shot: 1000

I don't think i need to explain further which weapon you would use to win the war. :)

Thank you all for the great explanation. cost effectiveness and little if no loss of explosive power makes sense. very informative. thanks again.

@cholin3947

THANK YOU...

Even a 'coil gun' would probably require the specification of 'ELECTROmagnet' for that to be accurate.

cholin3947, good point. However, the term rail gun is generally used for any reference to a gun with a magnetic barrel that increases the speed of a projectile with magnetics alone.

In Nimitz class submarines, they actually have 2 reactors and can easily provide the 32-33 megajoules required for the current version of the navy rail guns. The distance is, of course, classified but they are also working on a 60+ megajoule version. The upsides are the cost, range and the raw kinetic energy of this weapon. The downsides, until now, were that you could no stop the long range projectile once it was fired. This is looking like its becoming a permanent fixture in the defense arsenal.

However, at cost per shot, the airborne/ground based chemical laser is still a fantastic weapon. Satellite based lasers are even better and could theoretically vaporize targets from space. In my opinion, being able to drill a hole in your enemies targeting satellite, nuclear destroyer, missile, or railgun projectile is a much more fullproof weapon. Kinetics are awesome weapons though. One might argue that a dense enough projectile would be immuned to laser attack as well. I guess the two make quite a powerful arsenal indeed.

Ultimately, metamaterial science, leveraging the loophole in the laws of optics, providing the ability to have invisible weapons will be the biggest game changer. You cannot shoot, or shootdown, what you cannot see. To this end, all weapons will be useless against something invisible.

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

Also dont forget, an EMP fired in low earth orbit, over your enemies weapons, will make them all useless. Your power-grids and infrastructure all become mostly useless as well. An enemy fighting such a technologically advanced army will most likely employ these techniques to even the playing field. Weapons like these are cool but make war a scary game. The tactics used to circumvent these weapons are nothing short of devastating. An EMP that happens during your hearts t-wave, when it is repolarizing (every time it beats) will can stop your heart completely. Scary, scary scenarios at play when technological advancements on the battle field start to reach this level.

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

Intelligent smart GPS guided rounds, this is great information! I like to see new pictures of the rail gun and new videos PoPSCi, rather than the same old stuff.

I think a primary advantage, which no one has covered here is time on target. At Mach 8 a projectile will take a far shorter time to hit a target then a cruise missile will (Seconds versus minutes). Very handy if you are looking to hit a moving target. The kinetic energy is something akin to a 2000lb bomb.

I am somewhat concerned about using GPS though as several news stories have recently indicated that GPS is fairly easy to spoof, making this type of guidance less effective.

Good points timias, I am aware of fire control systems that can turn or flip the enemies incoming missles. I imagine the same might be done to this as well.

If GPS fails to get the target to where it is going these things can be laser guided too. Rounds like that exist now.

Round not target. My Bad.

Air friction on a projectile moving at Mach 8 will make quite an easy tracer to make out. Its trajectory will be easy to calculate because of this. Putting something in its path to absorb that impact, like discs (shot straight up into the trajectory of the rail-bullet) would be totally doable. Think skeet shooting. I doubt that very drastic directional adjustments can be made on a mach 8 projectile. I am thinking that beating this weapon is obviously not impossible. Using large solid metal Orbs, instead of dics, would riccochet the projectile off in drastically different direction. One thing about a mach 8 projectile... its speed will most likely be very constant and predictable.

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

I'm not so sure about the cost, once GPS guidance is added. If you look at the cost of an Excalibur GPS-guided 155MM round, that costs about $50,000. Don't know what a normal 155MM round costs today, but I'm pretty sure its well under $1000. This is the price of adding GPS.

And the railgun round will be accelerated far faster than an Excalibur, in all likelihood, exponentially increasing its price.

Also its important to know what the kinetic energy is of a shell over distance. Obviously after 200 miles of travel, the railgun round not be impacting at anywhere near 5600 mph.

This is not to say that this could turn out to be an awesome weapon.

Unless someone changed the laws of physics, a GPS guided rail gun is impossible. At Mach 8, the plasma sheath that would surround the round in flight would prevent the round from recieving GPS signals.

At what speed does the plasma sheath stop becoming a factor?

At Mach 8 the plasma shealth forms.

talchar, that is not correct:

A vehicle moving through the stratosphere
altitudes
40–50 km at hypersonic velocities
8–15 Mach is covered
by a plasma sheath. Typically, the plasma density "n" can be as high as 1018 m−3 with corresponding plasma frequency

 (e2n) 1/2
2
PI fL = wL = ---
(Me0)

of about 9 GHz. In Eq.
1, e is the electron charge −1.6
10−19 C, 0=8.8510−12 C V−1 m−1, and M is the electron
mass 910−31 kg. Therefore the plasma is opaque to
frequencies lower than 9 GHz. Direct communication
through such a plasma to and from the vehicle is impossible
because frequencies f suitable for long distance propagation
through the atmosphere are usually much less. For example,
the standard frequency used for navigational satellite systems,
including the global positioning system
GPS, are less
than 2 GHz. For the GPS, f =1.575 42 GHz.

100mhz can communicate through the plasma sheath. GPS totally doable. Just means that whatever is communicating with it isnt your standard satellite. Hmmmm :)

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

ya, ignore that first equation, that pasted horribly wrong. It is a real equation though.

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

This article explains a few ways to achieve the transmission in fact. Using the plasma shape itself with magnetics is also possible.

http://math.arizona.edu/~zakharov/1Articles/JAP_plasma.pdf

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

Nice job, D13.

Thank all of you for remembering the difference between a coil gun and a railgun. I don't want to be callous, but come on PopSci.

I actually have designed something a little bit more poweful than an ordinary everyday Zumwalt class. I designed what I think the next generation of naval warfare could be based on. I call it Leviathan.

SUbmersible aircraft carrier aremed with 48 cruisers and three, count 'em, railguns, positioned fore and aft. I thought of them being more like an NLOS cannon, getting the target and then compensating power and elevation accordingly. It was designed to work soley on the F-35 J/SF, and to launch off CV-22's at almost anywhere on Earth. How to power such a girl? Easy, SIXTEEN pebble-bed reactors, four for the railguns only, two for back up power. Rest goes to engine power, making it relatively fast.

ANy engineers out there? I know it needs work, but I can't help myself. I love to invent.

And to anyone wanting to put one of these railguns on a sattalite, wiki "Rods of God"