For those of you who like Big Picture/Strategic subjects

[The Chief]

Relocating MCAS Futenma to the landfill may be back on track as Hatoyama backs down on his threat to remove the MCAS from Okinawa, Unintentional consequences? Apparently the sinking of the S.Korean corvette Cheodan by a N.Korean sub gave them pause. See article : http://search.japantimes.co.jp/cgi-bin/nn20100523x1.html.

Currently in the Sea of Japan almost daily fire fights are on-going. I saw one report of a S.Korean ship firing on an unidentified object for 5 minutes but it turned out to be a flight of migrating cranes. Even the UN is involved. Think they are investigation the possibility of N.Korean violations of the 1953 cease fire agreement. HA!

 

[Will_T]

Big Red, good job keeping me in line, I lost my train of thought and have made an idiot of myself. But for the sake of continuing this back and forth...

"And then you need to justify how a battleship provides more effective fire support than a carrier, and at longer ranges than just over the horizon of the beach."
My friend wikipedia says that: "On January 31, 2008 the US Navy tested a railgun that fired a shell at 10.64 MJ with a muzzle velocity of 2,520 m/s. Its expected performance is a muzzle velocity over 5,800 m/s, accurate enough to hit a 5 meter target over 200 nautical miles (370.4 km) away while firing at 10 shots per minute."Assuming they're correct, it seems that this would be more effective at wiping out beach targets and interior targets then a carrier's air wing, especially monetarily. Also, this is a r&d piece, not a final gun, which would likely be stronger w/ longer range.



"The current system is the best compromise available with existing technology and industry."
I couldn't agree more, and your following statements too, we certainly don't disagree there. And I don't worry, but I do want to be a piece of that, and that's one of the reasons I'm joining the Navy.
Will.

 

[The Phiz]

From what I have heard, the one of the biggest problems with the railgun technology is longevity. They pretty much chew themselves up with the massive forces being applied to the barrel, as well as the ship. Doing some advanced aviator math for a minute- E=.5mV^2. Thats a really, really big V.

And as everyone in the Navy knows, 'R&D Pieces' don't exactly zip from the testbed to operational use in a few days...or years.

P.S. Good luck powering guns that powerful with todays conventionally powered ships.

 

[Will_T]

Phiz, from what I've heard the longevity is the biggest problem facing the Navy right now, there are huge amounts of energy poured into round, but a large portion tears apart the barrel as well. I guess that's a material science issue though.

And that kinetic energy (massive!) while problematic, would kill the target, big time. 500 miles above the surface is alot of gravitation potential energy
(PE=-Gm1m2/r-squared), which when converted back to kinetic energy of the ride down, would make the projectile hit at about mach 5!

And yes, energy consumption is an issue, but thats the price to pay for that destructive capability.

 

[helolumpy]

A mea culpa, I came across a memo from the CNO to Senator Kennedy about the DDG-1000 program (comparing it to a DDG-51) and the Burke class was listed as $2.55 Billion in FY 2010 dollars.
So my data that I cited earlier was a bit off. I personally blame the site where I got the data but I cited it without checking validity, so shame on me.

 

[Spekkio]

My friend wikipedia says that: "On January 31, 2008 the US Navy tested a railgun that fired a shell at 10.64 MJ with a muzzle velocity of 2,520 m/s. Its expected performance is a muzzle velocity over 5,800 m/s, accurate enough to hit a 5 meter target over 200 nautical miles (370.4 km) away while firing at 10 shots per minute."

So let's put the railgun at 50' above water...which gives ~8 nm to the horizon.

To be able to hit a ship at 200 nm, the target would have to have a mast head height on the order of over 4 nm.

In real world use, you'd probably only be able to hit something within 10 nm. And at that range, don't we have much cheaper 5" guns to do the dirty work?

Assuming they're correct, it seems that this would be more effective at wiping out beach targets and interior targets then a carrier's air wing, especially monetarily. Also, this is a r&d piece, not a final gun, which would likely be stronger w/ longer range.

I may be misunderstanding something about how railguns work, but the only way to get more range out of them is to alter the fact that the slugs are straight-shooting projectiles. Tough to do when they're traveling several times the speed of sound.

The argument of battleships vs. carriers was had in WWII...carriers won, and for good reason.

 

[BigRed389]

So let's put the railgun at 50' above water...which gives ~8 nm to the horizon.

To be able to hit a ship at 200 nm, the target would have to have a mast head height on the order of over 4 nm.

In real world use, you'd probably only be able to hit something within 10 nm. And at that range, don't we have much cheaper 5" guns to do the dirty work?

I may be misunderstanding something about how railguns work, but the only way to get more range out of them is to alter the fact that the slugs are straight-shooting projectiles. Tough to do when they're traveling several times the speed of sound.

The argument of battleships vs. carriers was had in WWII...carriers won, and for good reason.

http://www.navy.mil/search/display.asp?story_id=34718
Presumably they would be lobbed like a howitzer. AGS was supposed to also use a high trajectory.

 

[A4sForever]

...The argument of battleships vs. carriers was had in WWII...carriers won, and for good reason.

*sigh* ... that was never the 'question' of CV's vs BB's after Pearl (and that's what?? 70 years ago ??) ... and prior to 1941 it really only mattered w/in the NAVY bureaucracy of the 'good ol' boys club' ... the 'who you know, who you blow' club ... pre-1941 amongst those who were trying to protect their piece-of-the-pie/careers.

But when put up against Jap BB's or pitted against Jerry/Jap targets or saddled alongside CV's as an AAA platform or 'gunning' a potential USMC beachhead ... let's ask it again: what was the utility/viability of a 'big gun' BB ... ???

There was no question. Just ask any WW2 mud-Marine.

 

[Will_T]

http://www.navweaps.com/Weapons/WNUS_Rail_Gun.htm
Try this one spekkio, it'll give you a real good visual, and some more information too.

 

[Spekkio]

I don't disagree that railguns could be used to launch ballistic missiles, but then the question is: what does the railgun bring to the table considering its massive cost?

The whole point of a railgun is to send a relatively light round at high speeds in order to kill a target. We already have the capability to launch ballistic missiles, and using a railgun for indirect fire removes the advantage of sending the round out at extremely high speeds.

 

[BigRed389]

I don't disagree that railguns could be used to launch ballistic missiles, but then the question is: what does the railgun bring to the table considering its massive cost?

The whole point of a railgun is to send a relatively light round at high speeds in order to kill a target. We already have the capability to launch ballistic missiles, and using a railgun for indirect fire removes the advantage of sending the round out at extremely high speeds.

Where are you getting the ballistic missile from?

A ballistic projectile, yes, missile no. There are no chemical propellants involved. Furthermore, how does indirect fire remove the high speed advantage? Round goes way high up, comes screaming back down. Muzzle velocity and impact velocity presumably very close.

As far as theoretical advantages, rounds are cheap, safe (no explosives to store onboard), more rounds can be carried onboard (magazines won't need all the DC systems currently in place and are smaller overall), and if accuracy is somehow resolved, excellent penetrating effect.

Apparently they think they can resolve the accuracy issue with hardened GPS units based on LRLAP/Excaliber round performance. I would think though the rail gun acceleration may make it harder than we think when it comes to actually putting into real world application.

 

[Spekkio]

As far as theoretical advantages, rounds are cheap, safe (no explosives to store onboard), more rounds can be carried onboard (magazines won't need all the DC systems currently in place and are smaller overall), and if accuracy is somehow resolved, excellent penetrating effect.

I can guarantee you that rounds with GPS guidance will not be "cheap." Maybe cheaper than similar rounds with chemical propellant, but remember we payed multiple times the cost to develop and install a railgun in the first place. Additionally, if the rounds work as linked, they will have to be composed of materials strong enough to withstand atmospheric re-entry.

There are no chemical propellants involved. Furthermore, how does indirect fire remove the high speed advantage? Round goes way high up, comes screaming back down. Muzzle velocity and impact velocity presumably very close.

It takes the chemical propellants out of the equation, but the round will hit terminal velocity on its fall to the earth, striking with the same force as a round dropped from any height that can achieve that. At 200nm, the horizontal velocity of the round will be near zero...shooting it at just a 30 degree up angle cuts the horizontal muzzle velocity to 80% as it is. So you're essentially getting the same impact energy as you would by flying a plane overhead and dropping a gigantic bullet. I know the article says it impacts at mach 5, but I don't see how that is by applying simple mechanics to the situation.

 

[Kickflip89]

Phiz, from what I've heard the longevity is the biggest problem facing the Navy right now, there are huge amounts of energy poured into round, but a large portion tears apart the barrel as well. I guess that's a material science issue though.

And that kinetic energy (massive!) while problematic, would kill the target, big time. 500 miles above the surface is alot of gravitation potential energy
(PE=-Gm1m2/r-squared), which when converted back to kinetic energy of the ride down, would make the projectile hit at about mach 5!

And yes, energy consumption is an issue, but thats the price to pay for that destructive capability.

/sigh I wish I could let these things go.

PE is Gm1m2/(r_2 - r_1), not r^2. You wrote the force due to gravity, potential energy is force integrated with respect to distance. Plus, potential energy is really only valid in conservative fields (i.e. no air resistance)

If we're gonna nerd out, let's at least do it correctly.

 

[BigRed389]

I can guarantee you that rounds with GPS guidance will not be "cheap." Maybe cheaper than similar rounds with chemical propellant, but remember we payed multiple times the cost to develop and install a railgun in the first place. Additionally, if the rounds work as linked, they will have to be composed of materials strong enough to withstand atmospheric re-entry.

It takes the chemical propellants out of the equation, but the round will hit terminal velocity on its fall to the earth, striking with the same force as a round dropped from any height that can achieve that. At 200nm, the horizontal velocity of the round will be near zero...shooting it at just a 30 degree up angle cuts the horizontal muzzle velocity in half as it is. So you're essentially getting the same impact energy as you would by flying a plane overhead and dropping a gigantic bullet. I know the article says it impacts at mach 5, but I don't see how that is by applying simple mechanics to the situation.

The advantages are already summed up pretty comprehensively in the slide that's linked, though I'd also add cheap RELATIVE to alternatives. With a 200+nm range, alternatives are really more like either TLAMs or JDAMs. JDAM units are cheap, but the cost behind employing them by naval air is not in comparison. And we have 11 CVNs. We have 60 DDGs and 28 CGs by comparison.
And look at capability within that very formidable range. Within that range, it is in theory more capable than TLAMs or air strikes.

As far as the terminal velocity argument, who really cares what the final velocity is? Some 200lb heads apparently worked it out and think it works. I don't have the tools to do computer modeling accounting for hypersonic fluid mechanics or the air density variations at the extreme altitudes proposed, do you?
The real argument is if it the rounds are effective against targets when they arrive without explosives to provide a blast. We do at least know tungsten darts leaving the ground at hypersonic velocity do not come down gently like a leaf. It is going smash whatever it hits going really goddamn fast.
At the very least, a high density object traveling at high speed is going to be a great bunker buster, runway crater-er, etc. My worry would be its NSFS effectiveness compared to traditional artillery, particularly as it has no explosives to provide blast.

Of course, I bet that for the next 30 years at least, this is nothing more than mental masturbation as far as usefulness to the fleet.

 

[SynixMan]

Even if the railgun had a 200nm range, are we going to bring our super awesome CG(X) in to 20nm off a hostile shore to shell a target 180nm inland? Methinketh no.