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Subject: Iron Dome Faces Bad Numbers
SYSOP    1/10/2013 5:35:56 AM
 
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American God       1/10/2013 12:11:55 PM
An anti-missile defense is always going to run into numbers problems if it uses missiles. Because a high speed interceptor will likely always be more costly than a dumb (unguided) SSM or artillery round. What is needed is for laser technology to mature a little more. With lasers, there is no round expended and the only cost if the power. Recent advances in free electron lasers are bringing us to the brink of feasibility. The sooner we get there, the better.
 
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Skylark       1/10/2013 4:51:58 PM
Larger, longer range missiles will continue to be developed by Hamas and Hezbollah, but they will ultimately backfire on them if they get too big and/or too sophisticated.  The current crop of home-made unguided missiles have a nuisance feel to them (albeit deadly) and retalitation, however justified does tend to paint Israel as the bully.  This is not the case with larger, more sophisticated and more deadly missiles.  Larger missiles means Israel can justifiably retaliate with larger scale counter-attacks, which could include heavy missile barrages of their own.  (Guided and un-guided) Gaza cannot resist or sustain such a counter-strike, and the typical victim PR defense does not work if they use the heavy stuff.  Larger missiles require more set up, better trained crews and bigger storage and maintenance facilities.  Hamas cannot say that the resulting launches were caused by underfunded rogue splinter-groups or street punks trying to prove their machismo by attempting to kill women and children in their beds.  Large missiles are strictly military items the average Gazani could not possess, unless they were allowed by the Hamas regime to hold them and make use of them.  They also present awesome targets, particularly if a supply dump located in a densly populated area were to go off... something the Israelis would be happy to arrange with one, well-placed laser-guided munition.  In short, do not expect to see any scuds coming out of Gaza, unless they really want to see a Katusha barrage coming back at them.
 
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Belisarius1234    Railgun.   1/10/2013 4:56:46 PM
Bullets are cheaper than missiles.
 
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trenchsol       1/11/2013 8:56:10 AM
Does it make sense to supplement those missile based defenses with AA artillery of larger caliber, like 76mm ?
 
I mean, naval systems, like Otobreda, are advertised as universal, anti ship, anti - aircraft and anti - missile. They have decent range (20 - 30 km), decent rate of fire (85 - 120 rpm),  can defend an area, and don't need direct hit with explosive round and appropriate fuse in order to destroy or destabilize incoming missile.
 
DG
 
 
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American God       1/11/2013 10:06:40 AM
Gun AA is difficult for targets moving at great speed, has been since jets evolved at the end of WW2, which is why navies regard missiles as true AA, with guns strictly secondary, and mostly for surface warfare / land attack.
 
 
There is a land based version of Phalanx, Centurion, which is quite effective as a point defense, but has very limited range. You'd need a lot of them to make a meaningful impact on the problem.
 
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Belisarius1234    Railgun   1/11/2013 12:23:22 PM
The one under current test fires bullets at Mach 8.
 
Think of a large electromagnetic machine gun with bullets traveling at 5600 mph.
 
Then think of the next generation railgun with double that performance. 
 
That will kill ICBM RVs.
 
Bullets are cheap. Electricity is plentiful and easy to modulate. A gun is point and shoot. Missiles are expensive, have steer and  speed dropoff problems after burnout, and run out of supply too soon.
 
B.
 
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Sty0pa       1/12/2013 9:07:00 AM
Not to mention the "what comes up must come down" matter.
 
 
A phalanx throws up 4500 rpm, that's 1.1 metric TONS of crap flying into the air every minute splayed across an engagement area..
 
An Iron-dome missile is 90kg, sure, but it falls in pretty much one small area - I guess that's better? 
 
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Belisarius1234    Very valid point.   1/12/2013 7:15:02 PM
But if you are shooting 1 kg projectiles at Mach 8+ , the downrange fall may be a few hundred (300) kilometers away And if you are Israel or even threatened Americans trying to stop the terrorist incomings? Why should you even care if your spent ordnance falls on your enemy's territory? Over  friendly territory there is a standard solution. That is why you dug the bunkers and shelters. 
 
Please note that 20+ American civilians died from falling AAA rounds when the USN defended itself at Pearl Harbor. Was that acceptable along with the property damage the shells caused? Yes.
 
Incidental blue on blue happens even in a successful missile defense. How many Coalition planes did PATRIOT shoot down in Desert Storm?
 
Missile defenses have drawbacks, too.
 
B.

 

An Iron-dome missile is 90kg, sure, but it falls in pretty much one small area - I guess that's better? 

 
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WarNerd       1/12/2013 9:19:30 PM
The one under current test fires bullets at Mach 8.
 
Think of a large electromagnetic machine gun with bullets traveling at 5600 mph.
And a gun barrel that is damaged beyond use in less than 4 rounds.
Then think of the next generation railgun with double that performance. 
At 5kps your projectiles will burning up in the atmosphere.
That will kill ICBM RVs.
At what range? You are limited the accuracy of your gun mount, probably less than 6km.
 
Missiles have much longer effective ranges because the accuracy does not drop off.
Bullets are cheap. Electricity is plentiful and easy to modulate. A gun is point and shoot. Missiles are expensive, have steer and  speed dropoff problems after burnout, and run out of supply too soon.
1 bullet may be cheap, but if it takes 100 to get the job done it gets more expensive. And you have to include rest of the costs – the system to fire it, especially the cost of the gun barrel which has a limited life, the weapon mount including power conditioning equipment, the sensors to point it, and the logistics to support it all.
 
This is a railgun, so barrel life is big problem.  Let’s assume an order of magnitude increase in the number of rounds before replacement, say 50 rounds per barrel.
 
So the cost per round fired would be something like (These numbers are for illustrative purposes only, not actual costs.) $500 (cost of 1 projectile) + $100,000 (cost of a barrel) / 50 (rounds per barrel), or about $2,500/round fired.
 
Now lets add the other parts of the system.  Next there is the number of batteries required. Iron Dome’s missiles have a range of 40km, but let’s assume they are only effective out to 30km to allow some elevation. Let’s also go with the likely maximum effective range for the railgun is 6km, so you need 5x as many batteries assuming we are a line, not covering an area. Battery cost for Iron Dome is $40M including 100 missiles ($90,000 each), let’s say $30M for the detection and tracking radar and the battle management unit. The railgun will need nearly the same detection and tracking radar as Iron Dome and let’s assume we can link 5 batteries through one battle management unit, call it $20M per battery. In addition the railgun will have the weapon mount and power conditioning equipment, let’s call that another $10M per battery.
 
So you can buy 1 missile system for $40M, or do the same job with 5 railgun system for $150M, not including ammo and barrels.
 
Moral of the story -- Ammo is cheap. Delivering it to the target is expensive.
 
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Belisarius1234       1/12/2013 11:26:30 PM

s why the contact bushing to the rotor (slug) need refinement.  

Then think of the next generation railgun with double that performance. 


At 5kps your projectiles will burning up in the atmosphere.

 No it isn't. At those speeds, even aluminum survives long enough to survive the intended engagement.

That will kill ICBM RVs.


At what range? You are limited the accuracy of your gun mount, probably less than 6km.

More like 40 kms altitude. :Predict lead of 8 seconds difference is possible at 5000m/s  The RV can't jerk that much in descent unless you want to miss the carrier task force completely.  

Missiles have much longer effective ranges because the accuracy does not drop off.

 Hmmm. Missiles have an absolute upper bound in the lower atmosphere of Mach 10 (cylinder lift) before you have control problems, huge ones.

Bullets are cheap. Electricity is plentiful and easy to modulate. A gun is point and shoot. Missiles are expensive, have steer and  speed dropoff problems after burnout, and run out of supply too soon.


1 bullet may be cheap, but if it takes 100 to get the job done it gets more expensive. And you have to include rest of the costs – the system to fire it, especially the cost of the gun barrel which has a limited life, the weapon mount including power conditioning equipment, the sensors to point it, and the logistics to support it all.

Still cheaper than a missile and simpler to use. A stator roundis the slug mass and the bushing carrier. a few dozen bucks per slug. The gun is R&D costs. Fire control is COTS. 

This is a railgun, so barrel life is big problem.  Let’s assume an order of magnitude increase in the number of rounds before replacement, say 50 rounds per barrel.

 More like 200. And the design feature of disposable rails that can be extruded like spent shell casings is one idea that is under review. the "Barrel" is not a barrel. It is more like an open  frame mount for those rails 

So the cost per round fired would be something like (These numbers are for illustrative purposes only, not actual costs.) $500 (cost of 1 projectile) + $100,000 (cost of a barrel) / 50 (rounds per barrel), or about $2,500/round fired.

In the test rig, that mighty close to the actual costs per shot.  Slugs are a bit cheaper, the LINAC is more expensive.  

Now lets add the other parts of the system.  Next there is the number of batteries required. Iron Dome’s missiles have a range of 40km, but let’s assume they are only effective out to 30km to allow some elevation. Let’s also go with the likely maximum effective range for the railgun is 6km, so you need 5x as many batteries assuming we are a line, not covering an area. Battery cost for Iron Dome is $40M including 100 missiles ($90,000 each), let’s say $30M for the detection and tracking radar and the battle management unit. The railgun will need nearly the same detection and tracking radar as Iron Dome and let’s assume we can link 5 batteries through one battle management unit, call it $20M per battery. In addition the railgun will have the weapon mount and power conditioning equipment, let’s call that another $10M per battery.
 
 
 
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