Testing Points To Relevance Of Hyper Velocity Projectile For Zumwalt Destroyer's Dormant Guns

A version of the Zumwalt's beleaguered Advanced Gun System shot down a cruise missile with a Hyper Velocity Projectile during a major land-based test.

Youtube Screencap/USN/Joseph Threvithick

After the successful destruction of a cruise missile by a Hyper Velocity Projectile in a land-based test, the case for the U.S. Navy’s stealthy Zumwalt-class destroyers adopting the fast-flying ammunition has strengthened. These warships are arguably the Navy's most advanced and survivable, but also its most controversial — you can read more about them here — but their main guns, which take up the entire forward third of the 16,000-ton displacement vessels, lie dormant.  

During the recent trial, an Advanced Gun System (AGS) mounted on an M110 8-inch self-propelled Howitzer fired a Hyper Velocity Projectile (HVP) that downed a cruise missile target over the White Sands Missile Range. It was part of the U.S. Air Force’s Advanced Battle Management Systems (ABMS) test that ran from August 31 to September 4, 2020. You can read more about this major multi-faceted series of trials in this past piece of ours. 

Although the HVP was originally designed to be fired from an electromagnetic rail gun, propelling it to speeds of over Mach 7 and to a maximum range of over 100 nautical miles, it has also been adapted to work with existing naval guns that use traditional chemical propellant, including the Mk 45 deck guns found on existing U.S. Navy Ticonderoga-class cruisers and Arleigh Burke-class destroyers, and 155-millimeter tube artillery. As the test proved, the HVP can also be fired from a modified version of BAE Systems' Mk 51 Advanced Gun System (AGS) that arm the Zumwalt-class destroyer. These guns are currently dead weight, with no suitable projectile fielded. At present, a pair of 30mm cannons are the Zumwalt’s only usable guns.

The most recent land-based ABMS test — termed an “on ramp” by the Air Force — was intended to demonstrate how the system can “detect and defeat efforts to disrupt U.S. operations in space in addition to countering attacks against the U.S. homeland, including shooting down a cruise missile “surrogate” with a hypervelocity weapon,” the service explained.

As the test showed, at least indirectly, combining the HVP-armed AGS with the three Zumwalt-class hulls could add a significant new air defense capability to the already advanced warships. In particular, the new projectile could give the destroyers an effective and relatively low-cost counter to anti-ship cruise missiles or unmanned aerial vehicles, as well as conventional manned aircraft.

USN

USS Zunwalt with one of her AGS guns pointed into the air. 

“If you think about the kinds of threats you might face in the Middle East, the lower-end cruise missiles or a larger UAV, now you have a way to shoot them down that doesn’t require you use a $2-million ESSM or $1-million RAM because a Hyper Velocity Projectile — even in the highest-end estimates have it in the $75,000 to $100,000 range, and that’s for the fanciest version of it with an onboard seeker,” Bryan Clark, from the Center for Strategic and Budgetary Assessments told USNI News last year.

Joseph Trevithick

The three types of HVP rounds. 

The Zumwalt-class warships’ 155-millimeter/62-caliber AGS was originally expected to fire the Long Range Land Attack Projectile (LRLAP). When the costs of the munition escalated to $800,000 for a single round, the Navy ditched it on fiscal grounds and began to look at other options, including the Raytheon Excalibur 1b and BAE Systems Multi-Service Standard Guided Projectile (MS-SGP). Another BAE Systems product, the HVP, had been discussed as at least partial replacement for LRLAP, but it now appears to be a more tangible candidate for finally making the Zumwalt-class's deck guns relevant again. 

The types of missions the HVP will be able to undertake will depend on the gun system and platform, but currently, they include “naval surface fire, cruise and ballistic missile defense, anti-surface warfare and other future naval mission areas” according to BAE Systems. As such, the weapon could give the AGS a dual-role capability, tackling surface and land targets as well as airborne threats. 

USN

Firing the HVP from the AGS on the Zumwalt class would also provide greater range than from the far more common 5-inch Mk 45 guns. Those guns can supposedly reach out to a maximum of between 40 and 50 miles with the HVP round. According to available documentation, the HVP could be able to reach out to as far as 70 miles when fired from the AGS. This is approaching the range of the original LRAP rounds that proved too costly to procure for just the three Zumwalt class destroyers. Even if it turns out the range of the HVP and AGS combo is less, its anti-air capabilities offer more flexibility than the now-defunct LRLAP rounds ever did. 

BAE Systems

As originally schemed, the Zumwalts were expected to provide long-range fire from littoral positions to support troops storming enemy beaches and fighting inland, but the ethos of the stealthy destroyers has since changed to focus to blue-water operations. Nevertheless, the fact remains that the three destroyers were designed around two AGS installations each, and the Navy needs to find a way of making use of them — unless it decides to remove them altogether.

While the AGS aboard the Zumwalts has not yet fired the HVP, the projectile has been tested at sea previously. During the RIMPAC 2018 multinational exercise, the Arleigh Burke-class destroyer USS Dewey (DDG 105) fired 20 HVPs from its standard Mk 45 mounting.

Another phase of at-sea testing might well involve one or more of the three Zumwalts, especially since the Navy decided to assign them to Surface Development Squadron 1, or SURFDEVRON, a dedicated experimental unit that is tasked with investigating a broad range of cutting-edge technologies. It is a concept you can read more about here.

There is also an initiative underway that will examine equipping the Zumwalt class with another type of hypersonic weapon — the new Conventional Prompt Strike hypersonic missile, providing a fast-response standoff attack capability against enemy ships and targets on land. These plans would involve the removal of the warships’ Mk 51 AGS installations, so a decision may have to be made over which of these high-speed weapons to prioritize. 

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A land-based test of the AGS prior to installation aboard USS Zumwalt

The Zumwalts will also likely receive the SM-6 missile, which is primarily an anti-air weapon, but it has secondary anti-ship and land-attack capabilities that are growing more prominent. These missiles, when used to attack targets on the surface of the Earth, would act as quasi-ballistics missiles and would have terminal velocities approaching hypersonic. They can also be housed in the Zumwalts' existing Mk57 vertical launch system cells. You can read more about this promising and hugely versatile weapon here and here, but it combined with an HVP-capable AGS would give these ships a relatively wide array of highly-flexible additional strike and air defense capabilities. 

What we don't know is what modifications would be needed to the Zumwalt class destroyers' guns and their complex ammunition handling systems to make the HVP round work in an acceptable manner. Still, remodeling the guns and their below-deck infrastructure to work with the HVP may be a far more attractive and less costly option than ripping them out in full and replacing them with something totally different.  

We are still some way off seeing the full potential of the HVP, but it clearly shows considerable promise for lower-cost air defense both on land and at sea, as well as its other strike-related abilities. If the Zumwalt-class's already installed AGS can be adapted to accept it, it would address the embarrassing issue of a $23-billion program that has yielded three gun-armed warships with no ammunition to fire from them.

Contact the author: thomas@thedrive.com and tyler@thedrive.com