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April 27, 2011

Energy Weapons Arm Ships

(Aviationweek) Cannon do not have to be lethal to be useful.
Directed-energy weapons are being paired with traditional kinetic naval weapons to produce an advanced shipboard defense against people, small arms, light boats and unmanned aircraft. Options include non-lethal and low-power effects.
But the new combinations also offer lethal, higher-power capabilities for a much larger target set including enemy air defenses and anti-ship cruise missiles.
Plans include introducing high-power microwave (HPM) devices for counter-electronics attacks and high-energy lasers, say BAE Systems officials, who were in Washington for the Navy League’s Sea-Air-Space Exposition. Other options are to put the HPM devices into UAVs or small missiles that can be carried by unmanned helicopters like the Northrop Grumman Fire Scout to patrol ahead of and above ships.
The team of BAE Systems as integrator and Boeing, which is supplying the beam director, contends that the technology and platforms, both air and sea, are available and await only the miniaturization of some key components.
The current 15-month program puts a two-phase, 10-kw laser on a ship-mounted, Mk. 38 25-mm cannon. The cannon are being installed on virtually every surface ship in the U.S. Navy. And the laser-supplement program will wrap up with a land-based demonstration. No additional crew is needed to operate the one-man, remote-control, gun and laser system. The laser beam director is installed on the left side of the gun mount and a laser source is located below it. The laser has integrated power conversion and cooling.
The Mk. 38’s current electro-optical/infrared fire-control system would be used for initial detection of small boats, for example, at ranges of roughly 10 km (6.2 mi.). Targeting would then shift to the optics within the laser beam director at 8 km.
“That gives a high-resolution capability to determine how many crewmen there are on a small boat, if they have weapons and what kind of weapons they are,” says John Perry, BAE Systems’ manager of business development for advanced systems. “We then transition to a low-power, eye-safe, green-laser, visual-interruption mode.”
If the threatening behavior continues, there are more options available to the defenders.
“We can switch to the [10-kw] high-energy laser mode and start to engage at 3-4 km,” Perry says. “For a non-lethal engagement, we can target a portion of the boat away from the crew. It could be a radar or a deck-mounted weapon.” Escalating the engagement a bit more, “we could cook off the ammunition—machine-gun rounds, small missiles or rocket-propelled grenades. If it’s [an inflatable] rib boat, we can certainly puncture [air] bladders.”
The amount of time to create effects depends on the target range and material type, and can range from a couple to tens of seconds. The pointing system ensures that the laser beam stays within 3 mm of the aimpoint even with both ships moving in a rough sea.
“For a [10-kw] deck-mounted system like this, in the future we think we can [target] UAVs,” Perry says. “When you get to hundreds of kilowatts [of laser power], you can move into anti-ship, cruise missile defense. Our approach is to get an initial capability out to the fleet to give them a chance to figure out a concept of operations and how it complements kinetics.”
Northrop Grumman also is touting a ship-mounted, high-energy, solid-state laser that has produced “counter-material” effects. During the Maritime Laser Demonstration, which was conducted from the USS Paul Foster between October 2010 and April at the Pacific Ocean Test Range near NAS Point Mugu, Calif., the directed-energy system tracked and damaged moving, remotely piloted small boats.
“Results show that all critical technologies for an operational laser weapon system are mature enough to begin a formal weapon system development program,” says Steve Hixon, vice president for space and directed-energy systems. “Solid-state laser weapons are ready to transition to the fleet.”
The laser was installed on a decommissioned Spruance-class destroyer for the final demonstration, during which it was integrated with the ship’s radar and navigation system. In the final three days of trials, the laser operated more than 35 times in wave heights measuring up to 7.5 ft., says Dan Wildt, Northrop Grumman’s vice president of directed-energy systems.
Part of BAE Systems/Boeing’s air-target plan involves taking external clues from the ship’s radar so the gun/laser system can pick up a track, slew the gun mount and start tracking with optics within the beam director.
Another type of directed energy envisioned for the Mk. 38 gun mount is a BAE Systems-developed, HPM weapon with an anti-electronics attack capability.
By choosing the correct frequency span, HPM “has counter-electronics specific to swarms of small boats where you can stop their engines at [long] range,” Perry says. “Unlike lasers, HPM beams don’t need a lot of accuracy. With a fan [of HPM energy] you can target 10-30 small boats. If you can knock out 50-75% of the engines in a swarm, you can then concentrate on the remainder with lasers or kinetic [cannon].”
HPM weapons built for counter-electronics can disrupt or damage systems such as radars, missile guidance packages and sensor communications. Moreover, cannon have a limited number of rounds on board any ship, while lasers and HPM devices have a bottomless magazine as long as the ship is producing power. For example, 75 kw of ship’s power produced 10 kw of laser energy. Demands on the ship are less for HPM.
“We’ve looked at combining HPM, laser and kinetic weapons as miniaturization improves,” Perry says. “Today that’s a challenge; but you could put a laser on one Mk. 38 mount and an HPM on another and integrate their functionality through a single operator who can toggle the desired effects. Our models show that when we scale up an HPM that can fit on the Mk. 38, we can push the range out to hundreds or thousands of meters. Once you lock onto a target, we have radar apertures—for emitting the HPM—that deploy and focus on the target. The field of view is measured in [single-digit] degrees.”
What’s more, certain frequencies may be modulated so the HPM emitter sweeps through parts of the spectrum to affect specific types of electronics.
“We could have a Fire Scout [unmanned helicopter] out in front of a ship coming into port so it can radiate from above,” Perry says. “HPM can focus large amounts of effective radiated power on a point in space. HPM requires only a couple of seconds of power draw [from the ship] because the pulse width is so short it only requires a few kilowatts.”

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