NationStates Jolt Archive

"The gun is designed to launch these projectiles extremely far, somewhere in the neighborhood of 200 nautical miles, and their impact velocity is extremely high, somewhere in the vicinity of Mach 5."

http://news.yahoo.com/s/afp/20080201/pl_afp/usmilitaryweaponsrailgun_080201022901

For all those that use the international incidents forum, this is relevant to you. It seems that railguns are now quite possible in MT roleplays, and everyone who told me that my gun would barely be able to hit a kilometer long target at 100 miles are dead wrong. The railguns being developed will be able to hit a 5 meter wide target at a distance of well over 200 miles.

You can bet the range and speed of the projectiles is further than they're saying. Now, if I remember correctly rail guns have a problem wherein the rails that accelerate the projectile tend to be damaged by the firing. Damaged to the point where they're basically one shot weapons. One shot, then you have to replace parts. To say nothing of the horrendous recoil.

Recoil can be compensated for, the damage to the rails is a bigger problem as far as I know. Perhaps they're using superconducting whatsits to make it less fragile or something.

I always stuck with coilguns in my RP for that era though. Same general principle, less fragile.

Coilguns have their own special problems too. Though I think the problems with coil guns will be solved more readily than rail guns.

You can bet the range and speed of the projectiles is further than they're saying. Now, if I remember correctly rail guns have a problem wherein the rails that accelerate the projectile tend to be damaged by the firing. Damaged to the point where they're basically one shot weapons. One shot, then you have to replace parts. To say nothing of the horrendous recoil.

Recoil can be compensated for, the damage to the rails is a bigger problem as far as I know. Perhaps they're using superconducting whatsits to make it less fragile or something.

I always stuck with coilguns in my RP for that era though. Same general principle, less fragile.

Coilguns have their own special problems too. Though I think the problems with coil guns will be solved more readily than rail guns.

Can be? Are! I'm not sure why the military is more interested in railguns than coilguns, when the latter are known to work effectively. Hell you can build (http://www.coilgun.info/) your (http://wiki.4hv.org/index.php/Coil_gun) own (http://www.powerlabs.org/coilguns.htm).

http://www.diylive.net/wp-content/gaussian_pistol.jpg

Mach 5 at 200 miles? What the muzzle velocity have to be for that speed to be so high downrange? I smell a physics incompatibility.

Rail guns have a lot of potential, but the real power of rail guns will only be realised when we put them in space.

Now, if I remember correctly rail guns have a problem wherein the rails that accelerate the projectile tend to be damaged by the firing. Damaged to the point where they're basically one shot weapons. One shot, then you have to replace parts.

I think when this topic was brought up a year of so ago, I remember that point being made (possibly by you, or maybe it was DK).

I find it amusing that in a world of increasing asymmetry in relation to war - these things are still trumpeted as 'war winners' etc.

Can be? Are! I'm not sure why the military is more interested in railguns than coilguns, when the latter are known to work effectively. Hell you can build (http://www.coilgun.info/) your (http://wiki.4hv.org/index.php/Coil_gun) own (http://www.powerlabs.org/coilguns.htm).

http://www.diylive.net/wp-content/gaussian_pistol.jpg
Both the FOX story and this is old news to me, I saw the video of this gun being tested on Youtube and I must say that I'm not impressed. The problem with coilguns is that to get the muzzel velocity of a railgun usually requires more coils and that makes the weapon longer. Of course this whole point is kind of chicken mootle because missiles are already capable of striking targets over the horizon with greater accuracy than even high-tech artillery cannons. Maybe this will have a place in space-based weapon tech but it just doesn't seem like it would justify the cost of it in surface naval combat.

http://i30.tinypic.com/5cnjac.jpg

http://i30.tinypic.com/5cnjac.jpg

That's great Fass :p

Rail guns are utterly pointless. The only use you get from firing rails is so you can get a train to the enemy, and planes are much quicker.

And with the amount of power needed for a rail gun, wont a laser be just as good if not better?

LG is about to make a good point

And with the amount of power needed for a rail gun, wont a laser be just as good if not better?

Lasers don't hav much respect for that whole curvature of the Earth thing. :p

Lasers don't hav much respect for that whole curvature of the Earth thing. :p

Gravity bends light. Though you're right the curvature would be an issue beyond a few miles range. Of course there are other major problems with high power lasers. High powered lasers in atmospheres tend to turn the atmosphere hit by the beam into plasma, which diffuses the beam. Then of course there's the cooling requirements for the emitter itself, and the power requirements. Plus you need line of sight to the target. Over long range you've got optical scattering from the atmosphere and pollutants. Lots of problems.

Lasers in space are so much simpler.

And with the amount of power needed for a rail gun, wont a laser be just as good if not better?

No, because a railgun slug delivers kinetic energy and momentum. Instead of melting a few square inches, you drop a large amount of material into something at a horrendous speed. This tends to vapourise things.

Mach 5 at 200 miles? What the muzzle velocity have to be for that speed to be so high downrange? I smell a physics incompatibility.

From reading the article, Mach 7. Which is perfectly attainable, indeed, I'm surprised they didn't go higher. Ah well, they can simply increase projectile mass to help deliver extra energy.

The other problem with going too much higher is that you need to allow the particle to land, because with too high a velocity it simply won't come down in time, especially for indirect fire. Also, on Earth there's a hard upper limit of 11km/s for any targeting any other items on the ground indirectly. From reading the article, they're at about a quarter of that already.

Both the FOX story and this is old news to me, I saw the video of this gun being tested on Youtube and I must say that I'm not impressed. The problem with coilguns is that to get the muzzel velocity of a railgun usually requires more coils and that makes the weapon longer. Of course this whole point is kind of chicken mootle because missiles are already capable of striking targets over the horizon with greater accuracy than even high-tech artillery cannons. Maybe this will have a place in space-based weapon tech but it just doesn't seem like it would justify the cost of it in surface naval combat.

Very good point regarding the disadvantages of using a coilgun over a railgun, however, there is an advantage to consider when comparing both kinetic energy weapons to missiles. It is an advantage that has always been present when comparing traditional artillery to missiles.

Missiles can be intercepted, whereas artillery shells cannot.

Very good point regarding the disadvantages of using a coilgun over a railgun, however, there is an advantage to consider when comparing both kinetic energy weapons to missiles. It is an advantage that has always been present when comparing traditional artillery to missiles.

Missiles can be intercepted, whereas artillery shells cannot.

Improbable to intercept, but definitely not impossible.

Gravity bends light. Though you're right the curvature would be an issue beyond a few miles range. Of course there are other major problems with high power lasers. High powered lasers in atmospheres tend to turn the atmosphere hit by the beam into plasma, which diffuses the beam. Then of course there's the cooling requirements for the emitter itself, and the power requirements. Plus you need line of sight to the target. Over long range you've got optical scattering from the atmosphere and pollutants. Lots of problems.

Lasers in space are so much simpler.

SOme of those problems (atmosphere, pollutants and plasma) can be minimized or eliminated with pulsing lasers. But not all. Cooling is a major issue. Another issue is dwell.

Lasers don't hav much respect for that whole curvature of the Earth thing. :p

You tend to end up with a lot of collateral damage too.

Cooling is a major issue.Certainly in this age of global warming.:p

You can bet the range and speed of the projectiles is further than they're saying. Now, if I remember correctly rail guns have a problem wherein the rails that accelerate the projectile tend to be damaged by the firing. Damaged to the point where they're basically one shot weapons. One shot, then you have to replace parts. To say nothing of the horrendous recoil.
I tried using E = 1/2mv^2 to calculate some speed the ship would get, but I didn't get far. Though I think a mach 7, 20 kg projectile won't really affect a ship of around 20,000 tons.:p

Certainly in this age of global warming.:p


I tried using E = 1/2mv^2 to calculate some speed the ship would get, but I didn't get far. Though I think a mach 7, 20 kg projectile won't really affect a ship of around 20,000 tons.:p

Well, let's work it out.

Stick the numbers in, and the kinetic energy of the projectile is 6.25x10^10 J, or 62.5 Gigajoules. That seems like a fair bit, but if we presume the ship's weight is in metric tons, and rearrange the equation, we can calculate the resulting velocity of the ship. Which turns out to be 2.5m/s, not that much. I'll bet you get more recoil out of a 16" battleship gun.

Of course, the numbers change a little if it isn't metric tons, but even so it's not much of a change, and still less than 4m/s.

Seems to be a fairly practical system to me.

Certainly in this age of global warming.:p


I tried using E = 1/2mv^2 to calculate some speed the ship would get, but I didn't get far. Though I think a mach 7, 20 kg projectile won't really affect a ship of around 20,000 tons.:p

I demand simpler math. Nothing beyond 25, and no variables.:p

Well, let's work it out.

Stick the numbers in, and the kinetic energy of the projectile is 6.25x10^10 J, or 62.5 Gigajoules. That seems like a fair bit, but if we presume the ship's weight is in metric tons, and rearrange the equation, we can calculate the resulting velocity of the ship. Which turns out to be 2.5m/s, not that much. I'll bet you get more recoil out of a 16" battleship gun.

Of course, the numbers change a little if it isn't metric tons, but even so it's not much of a change, and still less than 4m/s.

Seems to be a fairly practical system to me.

Well, here's an article on the American Mk. 7 Gun, 16" type that is mounted on Iowa Class Battleships.

Well, here's an article on the American Mk. 7 Gun, 16" type that is mounted on Iowa Class Battleships.

My apologies, but I don't seem to be able to see the article. Retry?

SOme of those problems (atmosphere, pollutants and plasma) can be minimized or eliminated with pulsing lasers. But not all. Cooling is a major issue. Another issue is dwell.

That's why Phase Disruptor Cannons are better.

I forsee that to deal with asymmetrical warfare, accuracy will be as important as damage. A railgun would do well - concentrating its damage in a small area.

Click Stand;13417416']I demand simpler math. Nothing beyond 25, and no variables.:p
Mighty fine suggestion.:p
Well, let's work it out.

Stick the numbers in, and the kinetic energy of the projectile is 6.25x10^10 J, or 62.5 Gigajoules. That seems like a fair bit, but if we presume the ship's weight is in metric tons, and rearrange the equation, we can calculate the resulting velocity of the ship. Which turns out to be 2.5m/s, not that much. I'll bet you get more recoil out of a 16" battleship gun.

Of course, the numbers change a little if it isn't metric tons, but even so it's not much of a change, and still less than 4m/s.

Seems to be a fairly practical system to me.I knew someone could work it out:) (well, I can do that too, but didn't know if you could use E=1/2mv^2 for it.).

Metric tons? Are there any other?

Mighty fine suggestion.:p
I knew someone could work it out:) (well, I can do that too, but didn't know if you could use E=1/2mv^2 for it.).

Metric tons? Are there any other?

US short tons, that I know of. IIRC, they're 907kg. So the answer won't change much.

As for the equation, you can use any equation which has terms for the relevant variables. Just rearrange until you have what you want isolated, and then plug in the numbers.