Although Navy surface ships have a number of means for defending themselves against anti-ship cruise missiles (ASCMs) and anti-ship ballistic missiles (ASBMs), some observers are concerned about the survivability of Navy surface ships in potential combat situations against adversaries, such as China, that are armed with advanced ASCMs and with ASBMs. Concern about this issue has led some observers to conclude that the Navy’s surface fleet in coming years might need to avoid operating in waters that are within range of these weapons, or that the Navy might need to move toward a different fleet architecture that relies less on larger surface ships and more on smaller surface ships and submarines.
Two key limitations that Navy surface ships currently have in defending themselves against ASCMs and ASBMs are limited depth of magazine and unfavorable cost exchange ratios. Limited depth of magazine refers to the fact that Navy surface ships can use surface-to-air missiles (SAMs) and their Close-in Weapon System (CIWS) Gatling guns to shoot down only a certain number of enemy unmanned aerial vehicles (UAVs) and anti-ship missiles before running out of SAMs and CIWS ammunition—a situation (sometimes called “going Winchester”), that can require a ship to withdraw from battle, spend time travelling to a safe reloading location (which can be hundreds of miles away), and then spend more time traveling back to the battle area.
Unfavorable cost exchange ratios refer to the fact that a SAM used to shoot down a UAV or antiship missile can cost the Navy more (perhaps much more) to procure than it cost the adversary to build or acquire the UAV or anti-ship missile. In the FY2016 defense budget, procurement costs for Navy SAMs range from about $900,000 per missile to several million dollars per missile, depending on the type
SSLs, EMRG, and HVP offer a potential for dramatically improving depth of magazine and the cost exchange ratio:
- Depth of magazine. SSLs are electrically powered, drawing their power from the ship’s overall electrical supply, and can be fired over and over, indefinitely, as long as the SSL continues to work and the ship has fuel to generate electricity. The EMRG’s projectile and the HVP (which are one and the same—see next section) can be stored by the hundreds in a Navy surface ship’s weapon magazine.
- Cost exchange ratio. An SSL can be fired for a marginal cost of less than one dollar per shot (which is the cost of the fuel needed to generate the electricity used in the shot), while the EMRG’s projectile / HVP has an estimated unit procurement cost of about $25,000
Will the kinds of surface ships that the Navy plans to procure in coming years have sufficient space, weight, electrical power, and cooling capability to take full advantage of SSLs (particularly those solid state lasers with beam powers above 200 kW) and EMRG (electromagnetic railguns) ? What changes, if any, would need to be made in Navy plans for procuring large surface combatants (i.e., destroyers and cruisers) or other Navy ships to take full advantage of SSLs and EMRG ?
Railguns and Hypervelocity Projectiles
The two industry-built railgun prototypes are designed to fire projectiles at energy levels of 20 to 32 megajoules, which is enough to propel a projectile 50 to 100 nautical miles.
In January 2015, it was reported that the Navy is projecting that EMRG could become operational on a Navy ship between 2020 and 2025. In April 2015, it was reported that the Navy is considering installing an EMRG on a Zumwalt (DDG-1000) class destroyer by the mid-2020s.
Current railguns designs would launch projectiles at speeds of 4,500 mph to 5,600 mph or roughly Mach 5.9 to Mach 7.4 at sea level.
As the Navy was developing EMRG, it realized that the guided projectile being developed for EMRG could also be fired from 5-inch and 155mm powder guns.
When fired from 5-inch powder guns, the projectile achieves a speed of roughly Mach 3, which is roughly half the speed it achieves when fired from EMRG, but more than twice the speed of a conventional 5-inch shell fired from a 5-inch gun. This is apparently fast enough for countering at least some ASCMs. The Navy states that “The HVP—combined with the MK 45 [5-inch gun]—will support various mission areas including naval surface fire support.
One advantage of the HVP / 5-inch gun concept is that the 5-inch guns are already installed on Navy cruisers and destroyers, creating a potential for rapidly proliferating HVP through the cruiser-destroyer force.
There a total of 113 5-inch gun barrels are available in the US fleet (which could be a reference to 22 cruisers with two guns each, and 69 destroyers with one gun each); and that as a game-changing capability, it is guided and can be used at ranges of up to 26 nautical miles to 41 nautical miles for NSFS operations, for countering ASCMs, and for anti-surface warfare (ASuW) operations.
Vice Adm. William Hilarides, commander of Naval Sea Systems Command, said it will be at least 10 years until the railgun is fielded on new ships and potentially 30
years past that before the Navy considers removing powder guns from the fleet entirely and transitioning to energy weapons alone.
SOURCE- Congressional report on Navy Lasers, Railgun and Hypervelocity Projectiles