New Airborne Defense Against Small Swarming Boats

In a then-classified 2002 war game called Millennium Challenge, the Red Team, commanded by Lt. Gen. Paul Van Riper, sent waves of small boats, some loaded with explosives, to overwhelm the defenses of the Blue Team, representing the U.S. Navy. The results were grim. Blue Team lost 16 major warships?including a carrier. But the game was immediately restarted and Blue Team was eventually declared the winner.

Van Riper complained at the time that lessons were not being learned. Swarming speedboats represent a major threat to Navy aircraft carrier groups. Small boats are dangerous because they can emerge without warning from behind islands or other features, and weapons systems are designed to handle fewer, larger opponents, so carriers and other large vessels might be swamped before they can deal with the threat.

Today the Navy appears to be taking the threat more seriously. And existing defense technologies could be combined to create a defensive shield to detect and destroy boat swarms from a safe distance. The latest proposal involves an all-seeing eye in the sky that can pick out small boats at a distance and see over obstacles.

Raytheon's JLENS (Joint Land Attack Cruise Missile Defense Elevated Netted Sensor) is a blimp-based radar system that provides 360-degree, 24/7 coverage. The unmanned blimps or aerostats are 77 yards long. Each JLENS system, or orbit, has two of them, one with surveillance radar and one with a fire-control radar.

As the name suggests, JLENS was developed for defense against cruise missiles and can track aircraft. But it can also handle surface targets. This June JLENS went through a series of exercises on the Great Salt Lake to test its capability against swarming boats. A number of fast boats carried out tactical maneuvers at both high and low speeds, simulating an aggressive boat swarm. JLENS simultaneously detected and tracked the boats from over a hundred miles away.

JLENS can stay in position at an altitude of up to 10,000 feet for 30 days at a stretch. It provides the same sort of continuous coverage the military gets with manned aircraft like the E-2C Hawkeye but with fewer aircraft, less manpower, and at a lower cost, Raytheon says.

"One system provides the war-fighter the same around-the-clock coverage that it would normally take four or five fixed-wing surveillance aircraft to provide," says David Gulla, vice president of Global Integrated Sensors for Raytheon's Integrated Defense Systems business.

Once it's tracking the targets, the JLENS Fire Control System can pass on target information using a network known as Link 16, a system shared by U.S. ships, aircraft, and ground forces. Link 16 provides a secure, jam-resistant data link.

One potential weapon that the JENS systems could unleash is Raytheon's Small Diameter Bomb II. This is a new 208-pound weapon made to attack mobile targets; it also uses Link 16. Unlike SDB I, which was made by Boeing and is suitable for static targets, SDB II has an advanced seeker system with three different modes. The weapon uses laser guidance for situations where the target can be illuminated with a laser designator. Otherwise it has a millimeter-wave radar and an imaging infrared sensor that allow it to detect targets through cloud, smoke, and darkness.

The winged SDB II can glide for more than 45 miles, all the while receiving updates via Link 16. This allows it to drop into a "basket," the small area containing the target. The SDB II?s onboard sensors then precisely locate the target and lock on to it. The SDB II's memory contains a catalog of target types, Raytheon says, so it can distinguish a small attack boat from a nearby fishing vessel.

John O'Brien, Raytheon's SDB II Program Director, says the full networking and multimode seeker make it an effective weapon against swarming boats at all ranges. Plus, the relatively low cost and small size of the weapon should make it possible to deploy large numbers of SDB IIs. In theory, a single B-2 could carry over 200 SBD IIs?enough to take out an entire flotilla of swarming boats in a single sortie. (In practice, however, combat aircraft are seldom loaded to the maximum limit and carry a mix of weapon types.)

As always, though, money is an issue. Two JLENS systems have been built, but it is not certain that production will go ahead as originally planned. Meanwhile a Senate panel has recommended slowing production of the SDB II as Congress tries to slash the budget.

Yet small boats are not expensive, and there are ways of getting them cheaply. Iran recently announced that Revolutionary Guard's naval force would be making unlicensed copies of the British Bladerunner-51. This is one of the world's fastest boats, capable of more than 65 knots (74 mph). Together they form a threat that's not only asymmetric, but also lethally fast.

Source: http://www.popularmechanics.com/technology/military/planes-uavs/new-airborne-defense-against-small-swarming-boats-12175104?src=rss

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