Tom Boucher, railgun test director at the Naval Surface Warfare Center at Dahlgren, Va., says the center took delivery of a prototype gun built by BAE Systems. “We commissioned the gun last week, and we’ve fired it six times.”
Unlike the center’s large laboratory style launcher, the BAE Systems gun more closely resembles the size and configuration of 5-inch guns that are on ships today. But unlike those shipboard guns today, a railgun uses electricity instead of gunpowder to launch projectiles that travel faster and further than conventional ammunition.
“The lab launcher is big, and made from steel laminate,” Ellis says. “These new guns are composite, and are much more fit-and-form of what we would put on a ship. The barrels are about 10 meters, and they can train and elevate.”
“We’re at the 20-mega joule threshold. We’ll continue testing, and as we evaluate, we’ll take it up to 32-mega joules,” says Roger Ellis, EM Railgun program manager, Office of Naval Research.
The railgun can be effective against targets for strike missions, provide self-defense against anti-ship cruise and ballistic missiles, and deter enemy vessels.
The railgun employs intermediate energy storage with energy-dense batteries, much like hybrid cars. The batteries can be charged from the ship’s power generation system. “The battery bank charges the capacitors,” says Ellis. “It’s the capacitor bank that fires the gun.”
The use of batteries and a capacitor bank reduces the total amount of space required for energy storage. “This enables us to put railguns on ships that don’t have as large a power supply,” Ellis says.
“You should be able to fire about 50 shots before you would have to charge up the batteries again,” Boucher says.
The General Atomics gun will arrive in April to begin testing.
Up until now, NSWC Dahlgren has employed the massive laboratory style launcher designed to investigate barrel life and pulse power technology. The new guns look like a gun you would see on a ship. “These guns are more tactical than the laboratory gun,” Ellis says. “The intent and purpose is to test barrel life and structural integrity of the new guns.”
“The concept is scalable and modular size depending on which platform you want to put them on,” says Boucher.
The research effort for now is more focused on the gun than the projectiles. “The rounds we are firing are non-aerodynamic slugs. They match the interior ballistics of the barrel, but are intended to slow down quickly in order to keep within the safety footprint of the test range” Ellis says.
Ellis says the actual round will be sleek. “Think of the future projectile as a long, slender cone.”
The rounds would not require explosives, but rely on the mass of the projectile, traveling at hypersonic speeds, to destroy whatever it hits. llis says the rounds could have electronics inside to guide the projectile to a specified location. That will be a challenge, he says, because the electronics would have to withstand the extreme force of being fired at such a high velocity. “Don’t conclude the round will be going so fast or hot the electronics wouldn’t work or would melt away. Can internal electronics withstand those G-Forces? That’s part of the projectile development.”
“We’ve put instrumentation inside our test projectiles for testing and that’s been successful,” Ellis adds.
Last year, a Congressional committee zeroed out funding for the railgun project. “The mark from one of the committees was cleared and we currently have full funding,” Ellis says. “We’re adequately funded.”
Delivery of these prototypes ends phase 1 of the EMRG project. The second phase, from 2012-2017, will continue at the same level of funding, about $240 million over five years. In this phase, Ellis says the goal is to be able to achieve a “significant firing rate” of ten rounds per minute. By comparison, today’s 5-inch guns in the fleet have about a 20 RPM firing rate. Phase 2 will continue to investigate thermal management and cooling of the launcher and the pulse power systems while increasing power to 32 mega joules.
“We are aiming at a potential capability between 2020 and 2025, although planners are looking for ways to make that sooner,” Ellis says.
Eventually, railguns would be able to fire a round 100 miles, nearly ten times a 5-inch gun’s 13-mile effective range, and get there in about five minutes.
Images of the gun show a burst of flame, but Boucher says those photos and videos are taken at very high speed. The “flame” is actually the massive pulse of electricity – about 1 million amps when the circuit is broken – arcing across the launcher rails and the aluminum armature behind the projectile sliding down the rails literally wearing away as it speeds out the barrel at hypersonic velocity. The intensely hot particles of aluminum are “reactive with the atmosphere” and momentarily burn.
“It looks very dramatic on high speed video,” Boucher says. “But it’s less than you would see with a 5-inch naval gun.”
Industry has contributed to the effort, as well. “General Atomics is very committed to the program and the technology,” says Tom Hurn, director of railgun programs for General Atomics. “We’ve invested internal funds in excess of $20 million, including a subscale prototype.”
The General Atomics 2-mega joule Blitzer railgun was developed using company resources. Hurn says the range of options with the railgun technology is very scalable. “There are viable opportunities at multiple levels. The Navy will decide where the first opportunities will be.”
Dr. Amir Chaboki, program manager for electromagnetic railguns at BAE Systems, says “BAE is proud to provide the first 10-meter railgun to the ONR Innovative Naval Prototype.”
Chaboki says his company has been making advancements through the past year in both the gun and pulse power. “We continue to invest in critical technologies,” he says.