Thursday, September 08, 2005

Big Guns

Michael Goldfarb of the Weekly Standard wrote an article on the DD(X) program, appropriately titled DD(Rex). He makes some great points about how the advanced destroyer is likely to effect naval combat in the future. However, one line of thought about the gun returning to naval combat moved me to write the author:

Interesting article on the DD(X). Michael Goldfarb did a great job of laying out how truly revolutionary it is as a piece of naval architecture.

However, the notion that the ships would operate independently or as surface squadrons is off base. You would not use a platform with a dual-band radar for inserting Special Forces. This is what submarines and possibly the future Littoral Combat Ships (LCS) are for. The whole point of having a dual-band (X-band for missile illumination and fire control and S-band for long-range search) is to provide area low-to-high altitude air defense. The stealthiness is to reduce its radar horizon to enemy aircraft and missile boats to that it can shoot first. First and foremost, the DD(X) is intended to protect carrier battle groups that will be the mainstays of US naval strategy for well into this century. It's secondary mission is to support land forces ashore.

As for the Advanced Gun System, it is a land attack weapon. Period. There is little or no prospect of using it in a surface naval engagement, over the horizon or otherwise. The GPS-aided, inertial-navigation-system-guided 155mm shells are not intended to attack moving targets. A maneuvering ship simply cannot be engaged at over the horizon ranges with ballistic projectiles, unless the projectiles have a terminal active seeker or semi-active guidance with a spotter in the vicinity of the target. It moves too far while the shell is in the air. The gun is intended to provide forces ashore with artillery fire support, where spotters and sensors will be able to
send the GPS coordinates of the fixed target back to the ship.

The DD(X) will participate in surface naval engagements the "old fashioned" way: with Harpoon missiles from its vertical launchers and Penguin missiles from its embarked helicopters. Of course, if you find yourself in a surface engagement with a $3 billion ship then you haven't done your job properly. Modern anti-ship missiles are terrifying. You don't want to get anywhere near them. Airplanes, not guns, remain the future of naval warfare as practiced by the US. If you have planes, proceed with caution. If you don't, stay away from the enemy. In recognition of this, potential enemies will employ advanced diesel electric submarines armed with "carrier-killer" supersonic anti-ship missiles, such as the Russian P-500 Bazalt and P-700 Granit. To make matters worse, anti-ship missile makers are turning to imaging infrared seekers to counter radar stealth.

The future of naval warfare is air, surface, and submarine combatants fencing with ever more lethal missiles. The DD(X) is intended to be an integrated weapon system to enable US naval forces to survive and prevail in such an environment. It is not a harbinger of a retro era of broadsides and it certainly isn't a lone gunman.
To which Mike G. replies:

Thanks very much for your note. Very interesting.

I was told by the Admiral that this ship would be used to insert special forces, and that the gun could be used to give them fire support if necessary--though I don't deny the logic of your response. Still, I don't see why it would not be possible in the future to use the AGS against moving ships. Would the rail gun reach its target faster than the supersonic missiles? And isn't it likely that such projectiles would be able to track their targets?

Still, my purpose was mainly to highlight the exciting new technologies attached to the program. I may have gotten carried away a bit with the idea of a revival of the gun in ship-to-ship combat.
To which I reply:

Well, I'm certainly not one to contradict an Admiral. However, officers associated with programs tend to want to show that their systems can "do everything," even if they wouldn't operationally. It's the politics of funding. Still, you may have gotten a line on the DD(X) that I missed.

Gun rounds may be faster, but missiles carry more intelligence, sensors, and warhead strength. The Russian missiles I mentioned fly at Mach 1.6, have ranges in excess of 550 kilometers, can receive mid-course correction by datalink, and have active and passive terminal seekers. They have 750-1,000-kg HE warheads. That's a big boom. This is what you want to engaging moving ship targets. Range and smarts. And punch.

The railgun, it seems, is a range extender, although you still have the problem of locating, tracking, and engaging a moving target. Unlike a the GPS/INS-guided LRLAP, the railgun shell probably won't have any guidance at all, given that the forces of acceleration would be too crushing. This has been the main technical challenge on the guided projectile programs the US is pursuing now (LRLAP, Extended-Range Guided Munition (ERGM), and Excalibur). It will probably be a solid round to boot, relying on kinetic impact for killing power rather than a warhead. Even a shall traveling a ballistic course at something around Mach 5 takes time to reach a distant target. If that target is maneuvering then it will miss because the railgun round won't be able to change course. Great against a fixed land target. Not so good against a maneuvering one.

Again, I thought your technical summary and description of the implications of the DD(X) were excellent. I just wanted to throw a flag on your more romantic notions. Now, if we're talking about spaceships firing railguns line-of-sight, well now you may be onto something...


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