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I'm not sure I want to tell you in that case. And indeed, there are those who would argue that those who don't know, shouldn't know.

Also, it's Summer Glau.

Ah, Terminator/Firefly chick. Right on.

I didn't make myself clear enough, I don't think there could be any counter-measures.

Its traveling at mach 8... I did the math..

It is traveling at a top speed of 2722 m/s
The radar frequencies vary from 10^7 to 1.11X10^7

You will know exactly where it is, but if it is targeting a ship, you most likely won't be able to turn in time. If it is a land target, you can't just move a bunker or a fort.

Counter measures for something at mach 8 would have to be incredibly accurate. You would have to calculate the trajectory of the shot and launch something to intercept it, and all in the very little time before it hit your craft. I would imagine it extremely unlikely that you would be successful. And even if you did make it once, you'll have many more shots following.

What about reactive armour? In fact, would that even work on a ship? Any hit below the waterline would still let in water...maybe double hulls?

The Dreadnote wrote:What about reactive armour? In fact, would that even work on a ship? Any hit below the waterline would still let in water...maybe double hulls?

Reactive armour would still have an effect but it wouldnt be very effective given the size, shape, and speed of the slug.

Cover only the essential parts of the ship with reactive armor. Cuts down on costs and weight.

Although if they meet their aim of 10 shots per minute I doubt all that armour would help a great deal...

I doubt they would put reactive armor on a ship. For one thing, it would slow the ships speed (the panels aren't very hydrodynamic, otherwise they would have to build the ship from scratch with the panels in place already). Another thing is that reactive armor (the effective explosive kinds anyway), have the nasty sideeffect of killing nearby people when they do their job, so running around on deck would be a bad thing (although I think SOP for the Navy these days is to have everyone inside the ship during combat anyway, but it gets hairy when people are abandoning ship and getting ripped to pieces...).

I don't get how it can hit a target at up to 200 miles. I mean, this is more or less a direct fire weapon, yeah? So it'll be firing at something close to a flat line over those 200 miles - how often are targets going to present themselves at 200 miles away, with direct LOS? Surely there will be buildings and stuff in the way?

The Dreadnote wrote:What about reactive armour? In fact, would that even work on a ship? Any hit below the waterline would still let in water...maybe double hulls?

What we consider "reactive armor" is useful against shaped charges (i.e. the RPG-9). A solid slug of metal will go right through reactive armor. A weapon like this is very fearsome, with almost guaranteed destruction of the target and near instantaneous reaction. It wont take nearly as long as a cruise missile to reach it's target.

There isn't a countermeasure to this type of projectile. All of it's destructive capability comes from it's inertia, not explosive yield. Unless they make concrete that isn't prone to cracking.


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sebster wrote:I don't get how it can hit a target at up to 200 miles. I mean, this is more or less a direct fire weapon, yeah? So it'll be firing at something close to a flat line over those 200 miles - how often are targets going to present themselves at 200 miles away, with direct LOS? Surely there will be buildings and stuff in the way?

That would be phyiscally impossible to flat shoot something that far. I am sure they use it at an angle in their theoretical models.

Stormrider wrote:That would be phyiscally impossible to flat shoot something that far. I am sure they use it at an angle in their theoretical models.

It wouldn't be completely flat, but it'd be a lot flatter than anything else that gets used, yeah? To the point where it'd be quite useless against any target in a built up area...

sebster wrote:

Stormrider wrote:That would be phyiscally impossible to flat shoot something that far. I am sure they use it at an angle in their theoretical models.

It wouldn't be completely flat, but it'd be a lot flatter than anything else that gets used, yeah? To the point where it'd be quite useless against any target in a built up area...

what goes up comes down

if you fire at a high enough angle it can come down almost vertical

Reactive armour will do squat when faced with a projective hitting with such force.

There are things which can help, there is the goalkeeper sytems on ships which is the last ditch defence where all you need to do is hit it and deflect the course so it misses.

These things will not be fired flat. Even small arms are sighted so that the trajectory of the bullets means it will hit where the sight is aimed at. Unless you are firing something with wings all projectiles, if fired flat, will hit the ground at the same time as dropping the same round at the same height as the horizontal motion is independant of the vertical motion. You have to sight something for the round to travel in an arc on order to hit a target.

youbedead wrote:

sebster wrote:

Stormrider wrote:That would be phyiscally impossible to flat shoot something that far. I am sure they use it at an angle in their theoretical models.

It wouldn't be completely flat, but it'd be a lot flatter than anything else that gets used, yeah? To the point where it'd be quite useless against any target in a built up area...

what goes up comes down

if you fire at a high enough angle it can come down almost vertical

If you're firing it vertically you might as well drop bricks out of a helicopter. It'll be at terminal velocity anyway.

To get line-of-sight to a land-based target 200 miles away, you would have to be about 27000 feet up in the air, so I'm fairly certain they're not going to be firing it at things they can see... (Distance to horizon calculator: http://www.ringbell.co.uk/info/hdist.htm)

Did the math again, it would be fired at a 40 degree angle, roughly, in order to hit targets near maximum range... though there are some other factors in there I didn't account for.

So, chances are nothing will be in the way, it would fly clear over mountains and anything remotely in the way.

Rail guns don't need to have LOS so long as the slug doesn't reach escape velocity.

Damn it, ninjaed.

sebster wrote:I don't get how it can hit a target at up to 200 miles. I mean, this is more or less a direct fire weapon, yeah? So it'll be firing at something close to a flat line over those 200 miles - how often are targets going to present themselves at 200 miles away, with direct LOS? Surely there will be buildings and stuff in the way?

Nope, it can be fired at an angle much like an artillery piece. The physics work out in such a way that little energy is lost in the process.

To get line-of-sight to a land-based target 200 miles away, you would have to be about 27000 feet up in the air, so I'm fairly certain they're not going to be firing it at things they can see...

Who says they need line of sight? In the real world, we have what are known as "Forward Observers," "Joint Terminal Attack Controllers," etc. With the weapons ability to fire at an inclined trajectory, you only need someone up front to give coordinates for the fire control system to calculate firing angle, etc.

chaos0xomega wrote:
Nope, it can be fired at an angle much like an artillery piece. The physics work out in such a way that little energy is lost in the process.

Well, as with any ballistic projectile, energy is lost. It's simply that energy is then regained through free fall.

If energy were not lost we would be talking about shooting down satellites.

That's ultimately going to be the issue with using this as an over the horizon weapons; solid slugs require direct hits, and that isn't easy to achieve given a ballistic trajectory.

chaos0xomega wrote:Who says they need line of sight?

Sebster, whom you quoted.

I am sure they could deploy explosive rounds the same as they do now so indirect fire is just as effective.

Not necessarily, friction and all that.

One of the points of using a railgun is that you don't have to use explosives. You could get the same damage as a missile from a little bit of metal, which is much easier and safer to store.

Some of you are really underestimating just how much kinetic energy is stored in the fired round. Even if it is a solid slug, on impact, it will create a huge explosion.

This slug is leaving the gun with over 33 megajoules of energy and it's expected to get up to 64 MJ when it's fully operational! When that slug hits a solid object, there is going to be quite a large explosion and that object won't be there any longer.

There's no need to make explosive slugs, and that's the big advantage to the Navy. Not having to have a giant stockpile of explosives sitting inside your ship is a really nice change.

This is all very Star Trek and kinda pointless considering the whole thing is still experiemental.
I vote we abandon such comic book weapons and invest in real weapons. Baseball bats.

I'd rather take a bullet than take a beating from someone with a bat!

Elmodiddly wrote:This is all very Star Trek and kinda pointless considering the whole thing is still experiemental.
I vote we abandon such comic book weapons and invest in real weapons. Baseball bats.

I'd rather take a bullet than take a beating from someone with a bat!

I agree, I too would rather take a railgun slug to the head (or any body part for that matter, doesn't really matter) than get beaten to death by a baseball bat-wielding looney! Still, I say we modify the railgun to fire aluminium (yes, aluminium, that's how the rest of the world spells it! ) baseball bats! Imagine the horror!

Grakmar wrote:Some of you are really underestimating just how much kinetic energy is stored in the fired round. Even if it is a solid slug, on impact, it will create a huge explosion.

This slug is leaving the gun with over 33 megajoules of energy and it's expected to get up to 64 MJ when it's fully operational! When that slug hits a solid object, there is going to be quite a large explosion and that object won't be there any longer.

There's no need to make explosive slugs, and that's the big advantage to the Navy. Not having to have a giant stockpile of explosives sitting inside your ship is a really nice change.

This exactly, cutting down on explosives makes it much safer for the ship overall, Railguns have incredible range and destructive power.

"The main problem the Navy has had with implementing a railgun cannon system is that the guns wear out due to the immense heat produced by firing. Such weapons are expected to be powerful enough to do a little more damage than a BGM-109 Tomahawk missile at a fraction of the projectile cost"

Also,

Grakmar wrote:it's expected to get up to 64 MJ when it's fully operational

Our battleship is fully operational!


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AlmightyWalrus wrote:

Elmodiddly wrote:This is all very Star Trek and kinda pointless considering the whole thing is still experiemental.
I vote we abandon such comic book weapons and invest in real weapons. Baseball bats.

I'd rather take a bullet than take a beating from someone with a bat!

I agree, I too would rather take a railgun slug to the head (or any body part for that matter, doesn't really matter) than get beaten to death by a baseball bat-wielding looney! Still, I say we modify the railgun to fire aluminium (yes, aluminium, that's how the rest of the world spells it! ) baseball bats! Imagine the horror!

What about many railguns that fire baseball bats at such a distance that by the time they reach you they are going subsonic non lethal speed? HUH? WELL? Beated to death from hundreds of miles away

Soup and a roll wrote:

youbedead wrote:

sebster wrote:

Stormrider wrote:That would be phyiscally impossible to flat shoot something that far. I am sure they use it at an angle in their theoretical models.

It wouldn't be completely flat, but it'd be a lot flatter than anything else that gets used, yeah? To the point where it'd be quite useless against any target in a built up area...

what goes up comes down

if you fire at a high enough angle it can come down almost vertical

If you're firing it vertically you might as well drop bricks out of a helicopter. It'll be at terminal velocity anyway.

Good lord, will all of you go back to highschool physics please. It maintains a ballistic trajectory, therefore it comes down at almost the speed it was fired at, it how mortars and howitzers work


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dogma wrote:Rail guns don't need to have LOS so long as the slug doesn't reach escape velocity.

Damn it, ninjaed.

That shouldn't be a problem then, you need something like the force of a small yield nuke to launch something into space.


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Grakmar wrote:Some of you are really underestimating just how much kinetic energy is stored in the fired round. Even if it is a solid slug, on impact, it will create a huge explosion.

This slug is leaving the gun with over 33 megajoules of energy and it's expected to get up to 64 MJ when it's fully operational! When that slug hits a solid object, there is going to be quite a large explosion and that object won't be there any longer.

There's no need to make explosive slugs, and that's the big advantage to the Navy. Not having to have a giant stockpile of explosives sitting inside your ship is a really nice change.

Exactly, imagine an Abrams hitting something at 100mph. Thats going to be a sizable boom

youbedead wrote:Good lord, will all of you go back to highschool physics please. It maintains a ballistic trajectory, therefore it comes down at almost the speed it was fired at, it how mortars and howitzers work

bs. Anything that's had it's upward motion arrested by gravity - like a mortar shell past the peak of it's arc - will be accelerated downwards by gravity alone, eventually reaching terminal velocity. It maintains it's horizontal velocity just fine, however. Gotta think about vectors.

The Dreadnote wrote:

youbedead wrote:Good lord, will all of you go back to highschool physics please. It maintains a ballistic trajectory, therefore it comes down at almost the speed it was fired at, it how mortars and howitzers work

bs. Anything that's had it's upward motion arrested by gravity - like a mortar shell past the peak of it's arc - will be accelerated downwards by gravity alone, eventually reaching terminal velocity. It maintains it's horizontal velocity just fine, however. Gotta think about vectors.

Only if it it loses all energy on the way up and doesn't maintain a ballistic trajectory.

This is not a ballistic trajectory. notice that this is not a perfect parabolic curve


the missle lose the majority of energy at the apogee then falls to earth.

whereas the rail gun would use the trajectory of a projectile, which is a perfect parabolic curve


If the shell were to reach a speed of zero then fall it would only reach terminal velocity, but it still has forward motion form the firiing