- The U.S. Navy has removed the USS Zumwalt’s two Advanced Gun Systems.
- The guns, the ship’s main armament and reason for being, will be replaced by hypersonic missiles.
- The fate of the two removed gun systems is unknown.
The U.S. Navy has removed the fangs of the guided missile destroyer USS Zumwalt, intending to trade the two gun systems for new hypersonic missiles. The 155mm Advanced Gun Systems (AGS) were originally designed to attack land targets, but their precision rounds became unaffordable. The service intends to fill the empty space with a dozen Conventional Prompt Strike hypersonic missiles.
Goodbye AGS
The days of Zumwalt sporting her two recessed gun turrets is over. After the refit she will be even more featureless, with the 12 hypersonic weapon silos mostly under her bow deck.
An image of one of Zumwalt’s two 155m AGS systems appeared on USS Zumwalt’s official Facebook page and was picked up by Naval News. The photo—taken at Huntington Ingalls Industries’ Shipbuilding in Pascagoula, Mississippi—shows a crane lifting the 100 ton gun system up and away from the ship’s hull.
Zumwalt was equipped with two 155mm AGS, and both will be removed to make room for what comes next. The guns were especially designed for the Zumwalt class. The Navy had planned on buying 32 destroyers, as their firepower is valuable for supporting Marine Corps amphibious landings. The destroyers were meant to make up for the retirement of the Iowa-class battleships and their 16-inch guns in the early 1990s, to provide fire support, and to carry out strike missions in the land conflicts of the post 9/11 era.
Here’s an early BAE Systems advertisement for the guns:
The guns were formidable and capable of a sustained rate of fire of 6 rounds a minute—double that of comparable, land-based 155mm howitzers. Each could fire the precision-guided Long Range Land Attack Projectile (LRLAP) up to 63 miles. At $35,000 each, the LRLAP wasn’t cheap, but it would save money in the long run by requiring fewer rounds per target.
However, a combination of an economic downturn and cost overruns doomed the Zumwalts, then the guns themselves. The Navy cut the number of destroyers it intended to order from 32 to just three. This, in turn, drove the Navy to slash the number of LRLAP rounds it intended to buy, causing the price to balloon to $800,000 each—too expensive for even the U.S. Navy.
Although two of the Zumwalt class destroyers have been in service a total of thirteen years, their Advanced Gun Systems guns have been inoperable. The Navy never bought a single LRLAP for the guns, and rarely even showed the guns elevated out of their protected storage positions.
Hello CPS
In 2021, the Navy announced that it was considering installing the new Common Hypersonic Glide Body (C-HGB) missiles on the Zumwalt-class destroyers. C-HGB (shown above) is a hypersonic weapon that was co-developed with the U.S. Army and designed to strike time-critical targets. The Navy version (known as Conventional Prompt Strike) is largely identical to the Army version (known as Dark Eagle).
C-HGB is a boost-glide hypersonic weapon system. The weapon is essentially a large missile—so large, in fact, that it doesn’t fit in the Navy’s Mk 41 vertical launch missile silos. Once launched, C-HGB accelerates skyward, but unlike long range ballistic missiles, does not enter low earth orbit. It instead remains in the atmosphere, angles sharply downward, and glides toward its target.
Officially, C-HGB’s speed is “in excess of Mach 5”, or 3,836 miles an hour. Its real speed is believed to be Mach 17, or 13,043 miles an hour. C-HGB has a stated range of 1,725 miles—roughly the distance from Los Angeles to Chicago. At a steady Mach 17, the hypersonic weapon could cover that distance in just over 9 minutes. That said, the warhead-carrying glide body likely slows down significantly after the rocket motor burns out and friction with the surrounding air begins taking a toll.
A MiG-31 fighter carrying a Kinzhal hypersonic weapon. Kinzhal’s performance has disappointed in Ukraine, where it has been shot down by older Patriot missiles and successful strikes have made minimal impact on the ground.
Boost glide hypersonic weapons are believed to be more difficult to shoot down—they fly higher than the radars of short and medium range air defense systems (at least, at first), but lower than radars designed to pick up ballistic missile warheads. Only surface-to-air missiles meant to engage ballistic missiles (like the American Patriot and the Russian S-400) are believed to have a chance of shooting them down. Russia’s Kinzhal hypersonic weapon has been shot down several times by Ukrainian Patriot missiles, though it is more vulnerable to interception as a repackaged ground-launched ballistic missile .
C-HGB was originally meant to be first deployed on the Block V Virginia-class attack submarines, but the idle real estate on each Zumwalt catapulted the destroyers to the head of the line. All three ships—Elmo Zumwalt, Michael Monsoor, and Lyndon B. Johnson—will be fitted with hypersonic missiles by the late 2020s. Each AGS station will be replaced with six silos housing C-HGB weapons, for a total of 12 weapons per destroyer.
Stealthy Assassin
The US Navy’s new guided missile destroyer USS Zumwalt is moored to a dock on October 13, 2016 in Baltimore, Maryland,
The Zumwalt class destroyers were the first large surface ships designed with stealth in mind. Their sharp angles and largely featureless surfaces mean that relatively few radar waves bounce off the ship and back to an enemy radar. The end result is (reportedly) a 600 foot long warship that appears to be the size of a small fishing boat on radar screens—if it is detected at all.
The combination of stealth and hypersonic missiles will make for a warship that enemies will go out of their way to find, but they will have a difficult time doing so. C-HGB’s long range will mean that a Zumwalt destroyer can hide in an immense amount of ocean while remaining a risk to enemy targets. Once it launches an attack, a defender will have just a handful of minutes to detect, track, and shoot the hypersonic weapon down—if it is even within their ability to do so.
As Zumwalt’s twin 155mm guns are hoisted away to oblivion, the Navy believes it has found the next game-changing capability for the three gigantic warships. Despite the vast differences between a ship-based howitzer and a hypersonic missile, the mission remains the same: precision strikes on enemy forces on land. The ability to station precision-guided, hypersonic missiles at sea—on a mobile platform that can hide across thousands of square miles of ocean, no less—is a capability that should give any potential adversary pause.
Kyle Mizokami is a writer on defense and security issues and has been at Popular Mechanics since 2015. If it involves explosions or projectiles, he’s generally in favor of it. Kyle’s articles have appeared at The Daily Beast, U.S. Naval Institute News, The Diplomat, Foreign Policy, Combat Aircraft Monthly, VICE News, and others. He lives in San Francisco.
