Defense against railgun fire?

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Subject: Defense against railgun fire?
Habeed 9/24/2010 7:54:26 PM

Facts : the ship mounted 64 megajoule railgun the Navy wants will have a range of ~200 miles. A 32 megajoule prototype already exists, so the idea is less science fiction and more an engineering and integration challenge. The slugs will be guided, using guidance fins and some kind of sensor system. Guided artillery shells have existed for decades, and the electronics inside survive the acceleration just fine. I'm not sure how far along the Navy is in developing the ammunition but I think it can be taken for granted that they can do it. The Navy is planning on taking another decade to actually build ships sporting railguns but this is probably a matter of budget and priorities. If there was a pressing need for such a weapon I think it could be deployed within a few years. Once railguns become practical, would existing defenses work against the slugs? Railgun shots will be moving at several kilometers per second on a ballistic trajectory. They have to contain ferrous metals and will probably have a significant radar cross section (and stealthing them might not be possible with existing materials due to the frictional heat from traveling at mach 7+). Travel through the atmosphere at several kilometers/second would super-heat the projectile making it show up brightly on infrared and maybe even visible light. So you've got this glowing projectile streaking in from above, traveling several times faster than the bullets shot from a CWIS system. How would you defend against it? One last comment : railgun shots would not be able to fly around searching for a target like a missile can. To fire at a ship, you'd need to know it's exact position and possibly paint it with a targeting laser. I'm assuming a swarm of cheap, stealthy drone aircraft would search the seas looking for the enemy ships and act as a spotter. Also, railgun technology scales. Unlike chemical propellants where the explosion velocity limits your projectile velocity, if you throw more hardware into a railgun you can increase it's range and power smoothly and easily. Railguns with the same range as ICBMs are quite practical. I've been thinking that they would allow a nation without a decent Navy to build anti-ship "shore batteries".

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gf0012-aust 9/27/2010 4:46:45 AM

Potentially useful, but not the solution itself.

It's already part of the solution

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Reactive 9/27/2010 4:06:11 PM

An interesting article about Titanium Boride - lots of useful information.

nvl.nist.gov/pub/nistpubs/jres/105/5/j55mun.pdf

You wouldn't want to clean it with household bleach though.. : )

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gf0012-aust 9/27/2010 4:44:36 PM

Potentially useful, but not the solution itself.

unsure what happened to my prev (been happening a lot lately!)

it's already part of the solution, its already demonstrating utility, usefulness and benefit.

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Das Kardinal 9/28/2010 2:05:15 PM

no further comment. :)

but, my last stint in the US (as a private citizen) was rather enjoyable - looking at what they were doing and what we are doing.

hypersonics, plasma boundary layers in ballistics and cavitation in subs all have a common denominator......

Fluid dynamics ?

The XXIst century's finally shaping up. Railguns, flying cars, and robotic vacuum cleaners.

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C2 9/28/2010 10:05:18 PM

Fluid dynamics has been around for a while now, they teach it in 3rd year Aeronautics, these advancements seem to be linked to the maturity of exotic maturity in both fabrication and implementation.

Most likely significant growth in sophisticated weapon systems has more to do with high res CAD and sim tools then a newer understanding of scientific principles.

The trick with railgun tech would be to make the shell cheap and light enough to be carried in smaller craft (FFG) and accurate enough to hit...

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PPR Plausible 9/28/2010 10:06:08 PM

The rail gun has a lot of advantages over convential missile/gun technology:

1) It contains no explosives, making it safe to operate. Ships are often sunk when their own magazines or fuel are detonated. A rail gun wouldn't have this problem.

2) It's faster. As a direct fire weapon the projectile would be an almost instant hit. A projectile can travel mach 10 at sea level.

3) Projectiles will be cheaper. They can be "dumb" slugs, which would cost little to fire. Compare this to a million+ dollar missile

4) It is more flexible. The gun can precisely control how much energy is used to fire the projectile. It can be a low-velocity, indirect fire weapon like a mortar, or a high-velocity direct-fire weapon; or anything in between.

5) Unlimited range. Theoretically, the projectile can be ballistic. With some control rockets/fins on the projectile it could could hit a target anywhere on the planet. NASA is even considering it as a launch mechanism.

6) Capable of a kinetic-energy kill. In tests to determine if a rail gun could penetrate the armor of an M-1 that answer was, no, but the impact would destroy all the machinery/electronics on the vehicle and kill all the crew. It was like scrambling an egg without breaking the shell. A kill is a kill. By comparison, the most powerful rail gun so far has fire 32 megajoules, compared to a 16-inch gun fired from an Iowa-class battleship, which rate 355 megajoules.

7) Less weight than a conventional gun.

All that being said, the technology is clearly not there yet. But you can expect a gradial introduction over the coming years. How quick is just a matter of money. The first real-world application will probably be as a catapult for navy aircraft. Smaller guns will probably be first, maybe as a tank-gun. A 2025 time frame is reasonable.

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PPR Defense: less is more 9/28/2010 10:31:48 PM

Ironically, the best defense against a rail gun may be to go light. During the Battle of off Samar in World War II, a force of Japanese battleships attacked an American force of destroyers, escorts and escort carriers; all with little or no armor. The battleship guns were so powerful they penetrated the destroyed and carriers completely without detonating. While they did damage, it wasn't the sort of damage one expected. It was like being shot by an M-16, but the bullet doesn't hit bone and just carries on through without transferring much energy to the target.

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C2 9/29/2010 3:32:14 AM

Who says that a railgun round wont be explosive? Using layers of reactive metals the force of impact would compress the round enough to create a considerable bang and still transfer kinetic energy.

The best defense is to not get hit...a layered counter-intelligence and asymetrical strike capability is always required when facing a significant threat system.

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doggtag 9/29/2010 8:47:45 AM

The rail gun has a lot of advantages over convential missile/gun technology:

1) It contains no explosives, making it safe to operate. Ships are often sunk when their own magazines or fuel are detonated. A rail gun wouldn't have this problem.

2) It's faster. As a direct fire weapon the projectile would be an almost instant hit. A projectile can travel mach 10 at sea level.

3) Projectiles will be cheaper. They can be "dumb" slugs, which would cost little to fire. Compare this to a million+ dollar missile

7) Less weight than a conventional gun.

1) Is/will railguns really be safer? Just how much electricity are we talking about, and in a seawater environment?

AIUI, unless it's de-ionized water, it generally doesn't behave well with any electricity.

What happens if the electrical conduits powering into the gun are battle damaged (or other structural issue resulting in large amounts of electricity shunting/shorting into where you least want it), how well will the nearby metal bits of a ship resist passing that high voltage and current to some place you don't want that high current and voltage going into?

My guess is, the extra shielding needed to create insulation throughout the ship for those electrical levels will drive up ship costs, so any gains in not using chemical propellants may be lost in other areas....

2) But without some form of exotic high-temperature coating, how long can Mach 10 be sustained in the thicker (higher-friction) atmosphere down near sea level?

And if we're firing the gun at/near sea level, that suggests low trajectory, meaning non-ballistic and therefore a much shorter range correspondingly...

3) How will the projectiles be cheaper?

As mentioned in numerous other discussions, chemically-propelled PGMs from artillery tubes are still fairly expensive because the mechanisms in the shell need hardened against the launch stresses.

Do you really think we can fire railgun projectiles several dozens of miles (hundreds of km even?) and have them hit precisely and exactly on target everytime without some form of endpoint guidance, meaning sensors, signal recievers, and/or mechanisms that all must be strengthened to withstand such high launch stresses?

4) But firing it (lobbing rounds) indirectly like a mortar or howitzer means you succumb to their inherent accuracy issues because lower velocities and high trajectories means, again, you're more susceptible to cross winds and other atmospheric/meterological interferences, just like current chemically-propelled artillery is.

5) Unlimited range? You mean, like intercontinental? But again, as soon as you start putting guidance and control components into a shell that can take that quick of an acceleration, it will get very expensive per round.

Missiles will always outperform in this aspect, because their gentler acceleration curve allows more affordability in components that don't need to be

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JFKY Dogtag 9/29/2010 10:27:56 AM

You mention the irony of naval artillery being surpassed land-based artillery. And I think it follows logically from the tactical/technical history of naval warfare from the 1920's until now.

Prior to a/c capable of carrying torpedoes and armour-piercing bombs, the naval rifle was the PRIME combat weapon of navies. After 1945 the prime weapon was either the air-delivered bomb, USN or the missile, USSR. As such naval rifles were relegated to a secondary position. Naval technologic trends were to develop missiles and other air delivered weapons and nuclear weapons. Naval rifles were for secondary roles, air defense or shore bombardment. As such they received short shrift in terms of research, at a fundamental level.

Land-based artillery, in the 1970's and 1980's, at least did not suffer from this lack of focus. Now thru the 1950's and 1960's ground forces focused on missiles and nuclear weapons, too. However, with the advent of the 1970's and a re emphasis on conventional combat artillery, in its tube form, came more to the fore.

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