By Richard R. Burgess, Senior Editor, Seapower Magazine

BAE Systems (Booth 613) is developing a hypervelocity projectile, or HVP, for the U.S. Navy’s Mark 45 5-inch gun as a counter-unmanned aerial system option to engage aerial targets.

The Mk45 is the gun installed on the Navy’s Arleigh Burke guided-missile destroyers (DDGs) and Ticonderoga-class guided-missile cruisers, as well as on some warships of 11 other navies. More than 220 Mk45 guns are in service worldwide.

“We’re always looking to improve performance of the gun and the gun weapon system in general and the hypervelocity projectile is the next iteration of various improvements that we’ve done over the years,” Tate Westbrook, BAE Systems’ director of Naval Guns and Missile Launchers, said during an interview with Seapower.

The Mk45 gun was among the weapons the Navy used to successfully engage Houthi drones and cruise missiles during action in the Red Sea. In a speech at January’s Surface Navy Association Convention, Vice Admiral Brendan McLane, commander of Naval Surface Forces, said as one example the DDG USS O’Kane “protected a merchant convoy against hostile UAVs and employed their 5-inch gun to successfully defeat the threat.”

“We are currently under contract for a developmental effort with the Navy,” said Westbrook, who as a Navy captain commanded a DDG, a squadron of DDGs and a fleet task force. “I can’t get into the specifics on how many projectiles we’re building for them or how many ships it’s installed on or going to be installed. At this point, it’s very much a cooperative development program between us and Naval Surface Warfare Center Dahlgren.”

Westbrook described the HVP round as fitted with a sabot, a casing that enables the round to fit in a gun barrel of a larger diameter. BAE Systems developed such a round with sabot for its Rail Gun, an electromagnetic gun developed in the 2000s but cancelled in 2016. The HVP has since been improved and adapted for systems in development. BAE Systems is under contract with the U.S. Army for an HVP with a 155-millimeter sabot for its Multi-Domain Artillery Cannon System, which includes a dedicated radar, vehicles and cannon, as well as an HVP.

“The projectile itself is almost 100% the same between the Army version with a 155-millimeter sabot and the U.S. Navy version which is a 5-inch sabot or 127-millimeter, but the projectile that proceeds on the way to the intercept of the target is almost 100% the same between an Army version and a Navy version,” Westbrook said.

Westbrook was not at liberty to discuss the HVP’s fuzing but noted “the importance of what a gamechanger this program is going to be. The Navy has very much limited performance discussions of how the fire control system actually works and what’s happening on board, but what I can tell you is that it’s got an onboard processor inside the projectile. It has four control fins and can maneuver to the target. The ship is providing information to the round in flight, and it does onboard calculations to maneuver to inner subject.”

When the round is fired, the sabot peels away in four pieces from the projectile.

Westbrook said the Mk45 itself needs only minor modification to ensure that the gun “basically communicates with the round and recognizes it [and] provides initial data to the projectile before it’s fired.”

He said additional tests of the HVP are planned for on land and at sea.