US Air Force Wants to Revive Navy’s Aborted Railgun Shell Programme to Shoot Down Cruise Missiles

The United States isn’t the only country experimenting with railgun technology. China has spent years tinkering with its deployment at sea, while Japan has researched it for use to target hypersonic missiles. Railguns use electromagnetic force to fire metal slugs at incredibly high speeds, and require an immense amount of energy to operate.

The US Air Force wants cash to create and field test a self-propelled ground-based railgun system capable of shooting down enemy cruise missiles.

In a Fiscal Year 2023 budget request published on the branch’s Financial Management and Comptroller website, the Air Force proposes reusing rounds originally developed for the Navy railgun programme, which was terminated last year, to create an aircraft “transportable/deployable variant of the technology for use at US bases to protect against cruise missiles”.

The prototype, dubbed the "Hypervelocity Ground Weapons System" (HGWS), needs to be small enough to fit into a C-130 Hercules turboprop transport, and is one of a number of “developmental prototypes” the Air Force wants to build and test out for $89.1 million.

“A C-130 transportable/deployable Hypervelocity Ground Weapons System (HGWS) prototype will be built and integrated into a Joint-Service operation that will rapidly deploy the HGWS prototype, integrate the system into an existing joint service battle management system, and test its effectiveness against incoming cruise missiles as part of a life fire [sic] experiment. The HGWS prototype will rapidly deploy to a remote location to understand the effectiveness of expeditionary operations”, the proposal reads.

No additional information about the system is provided. However, The War Zone, which first reported on the funding request, said the description of the HGWS appears “virtually identical” to a base defence concept known as the "Multi-Domain Artillery Cannon" (MDAC), which the Air Force unveiled in 2021.

The Navy dropped funding for its own research into electromagnetic railguns and the associated special hypervelocity rounds last year after facing a budget crunch (the word "crunch" being relative – given the Pentagon’s massive $705 billion military budget in 2021).

The Navy’s railgun concept was successfully built and fired, but engineers failed to find a means to resolve the issue of extreme wear and tear on the system – with the rounds wearing out the gun barrel after it was fired just a few times. The immense amount of energy required for the gun to accelerate shells to over 7,000 km per hour - some 20 megawatts – is enough to power as many as 18,000 US homes for a whole year.

Along with the United States, the People’s Republic of China and Japan have poured resources into railgun technology. The PRC installed a railgun on a Type 072II-class landing ship in 2018 and adopted a new power generator simulator to the design of the US Zumwalt-class destroyer in 2020 to power both railguns and the electromagnetic catapult systems used by aircraft carriers. Soviet scientists experimented with railgun technology during the Cold War, and Russian engineers have tinkered with a prospective railgun round for use against tanks since at least the mid-2010s.