It’s been almost a decade since the US Navy conducted its first demonstration of a prototype electromagnetic railgun, and the technology has advanced significantly in the last ten years. The Navy is currently considering whether to proceed with at-sea tests of its railgun technology, or canceling those tests in favor of funding increased R&D and expanding the number of platforms that might one day adopt the weapons.
As with a number of cutting-edge military technologies, there’s some degree of controversy over whetherthe Navy’s Hyper Velocity Projectile (HVP) and electromagnetic railgun (EMRG) are worth the cost and expense of their own development. While the HVP is intended to be used as ammunition for the EMRG, it’s not a requirement — in fact, the HVP is designed to be fired from a wide range of platforms already and can be fired by conventional guns. The table below, courtesy of The Strategist, shows the various combinations and costs of various weapons. AGS stands for Advanced Gun System (currently mounted on Zumwalt-class destroyers) while LRLAP is the Long Range Land Attack Projectile.
Development on the HPV seems to be proceeding fairly smoothly, and while the projectile would have to be integrated into the weapon systems of existing Navy cruisers, that task does not seem to present any unusual challenges. The larger question dogging both the railgun project and its ammunition is whether the benefits outweigh the costs.
Cost, ironically, is at the heart of the ECMG and HPV development programs. In the past, we’ve talked about how guided missile systems face high barriers partly because the technology and expense of building a missile that can hit another missile is much higher than building a missile and launching it at someone to begin with. If it costs $1 million to block a $10,000 missile, you’ve got a serious problem. The second issue is the limited number of SAM (surface-to-air missiles) that any single ship can carry. These two problems are referred to as the cost exchange ratio and the depth of magazine.
An HPV round fired from a railgun leaves the barrel at Mach 7.5 (Mach 3 if fired from a conventional gun) and is theoretically fast enough to counter a anti-ship cruise missile. Replacing expensive SAM batteries with projectile weapons could dramatically cut costs and improve the chance of a ship surviving a pitched battle. Meanwhile, an ECMG, once fully functional, could deliver rounds at distances far larger than any other projectile — and a 20-32MJ railgun could deliver a serious punch.
One significant question about railguns, however, is whether the Navy can actually retrofit its current cruiser lineup to use them. The power requirements for the Navy’s next-generation weapon system require a 25MW power capacity. The Navy’s Zumwalt-class destroyers can supply this, having been designed with 58MW of spare electrical capacity and the ability to quickly shift its distribution between propulsion and other on-board systems. Unfortunately, cost overruns led the Navy to aggressively downsize its plans for the Zumwalt class from 32 ships down to three. This means the Navy would have to find a way to shoehorn a 25MW weapon into the Arleigh Burke class of destroyers — and they currently only provide 7.8MW of power total. Retrofitting them for railguns might prove extremely difficult.
It’s unclear if railguns will prove to be decisive battlefield weapons, a fringe capability carried by just three US Navy vessels, or an expensive boondoggle. Then again, the program seems to be in absolutely pristine condition compared with the F-35 — so I guess it’s all in how you choose to compare.