An array of unmanned surface vehicles soon will take to the seas
By RICHARD R. BURGESS, Managing Editor
In the fast-developing world of unmanned vehicles, it is aircraft that receive much of the attention from the public and press. Their high-profile reconnaissance successes in the 1991 Gulf War and the 2002 assassination of six al Qaeda operatives in Yemen by an armed CIA Predator drone drew widespread attention to the recent progress that has been made with these technologies.
U.S. combat commanders are clamoring for more unmanned aircraft for surveillance tasks, and in the future, advanced unmanned craft will take on some of the military’s more dangerous missions, such as the suppression of enemy air defenses.
Meanwhile, the Navy now is preparing a new generation of Unmanned Surface Vehicles (USVs) for a variety of tasks, many linked to the service’s recent efforts to improve its capabilities to fight in littoral areas and locate modern-day diesel submarines that have proven to be elusive, particularly in shallow, high-traffic seas where much of the Navy’s future operations are likely to occur.
Several of the USVs are designed as workhorses for the future Littoral Combat Ship, a new class of relatively small, fast multimission vessels that will conduct much of its antisubmarine, mine countermeasures and surface warfare missions by launching sensors and weapons from unmanned vehicles.
The Navy is experimenting with two new USVs for that purpose, including one designed to tow mine warfare sensors.
The USVs in development represent a fundamental change for the Navy. Heretofore, most have been modifications of the service’s venerable rigid-hull inflatable boats (RHIBs), which were originally designed as manned craft. The new generation of USVs is designed to operate as unmanned vehicles, and initial sea trials indicate at least some are superior to the RHIBs due, for example, to their stability and speed.
Antisubmarine USV Selected
In May, the Navy’s Space and Naval Warfare Systems Command awarded a contract potentially worth $11.3 million to General Dynamics Robotic Systems, Westminster, Md., for the first two USVs for the Littoral Combat Ship program. Contract options may increase the order to four vehicles.
The prototypes will be based on the Blade Runner commercial power racing boat designed by Navatek Ltd., Honolulu, Hawaii. They will have aluminum hulls, but the hulls of production models may be made of fiberglass or other material, said Scott Myers, president of General Dynamics Robotic Systems.
The boats’ 900-horsepower diesel engines, still to be selected, will power two water jets. Approximately 11 meters in length, the boats will feature W-shaped monohulls, “with sharp, knife-like sponsons on the sides,” according to information obtained from the Navatek website.
One purpose of the design is to trap a cushion of air between the hull and the sponsons to provide lift, reduce shock and produce a smoother ride relative to a conventional planing monohull that skims across the surface. The shape allows for coping with heavy seas, a major challenge for USV builders because of the sensitive electronics they are designed to carry.
The General Dynamics boat will be designed to deploy antisubmarine sensors such as sonar systems and acoustic arrays. General Dynamics is to deliver the two prototypes by June 2007 and will put the boats through nine months of trials, initially at Naval Air Station Patuxent River, Md.
High Tow-Force and Hydrofoils
Meanwhile, the service is trying to reduce the number of types of craft that would be launched by the Littoral Combat Ship. Currently, the Navy is planning to deploy one air, two surface, one near-surface and one undersea vehicles on the Littoral Combat Ship.
To achieve that end, the Combatant Craft Division of the Naval Surface Warfare Center Carderock (Md.), is experimenting with two USVs at Patuxent River and Fort Monroe, Va. Built by Maritime Applied Physics Corp. of Baltimore, the craft are designed to accommodate the missions of the Littoral Combat Ship.
One vehicle, called the High Tow-Force Vehicle, is an engineering development model designed for mine countermeasures, said Landon Hutchens, spokesman for the Naval Sea Systems Command.
“This is one of the first steps toward developing and evaluating a common, multimission USV, built to meet our requirements in support of both the mine warfare and antisubmarine warfare mission packages,” he said.
The High Tow-Force Vehicle is a conventional 39-foot boat with a planing hull that skims over the water. At operational speeds of up to 20 knots, it is optimized to tow minehunting equipment such as side-scanning sonars or antisubmarine systems such as towed acoustic sensor arrays. It uses tunneled propellers designed for low-speed boats with a towing requirement.
“They can generate a significant amount of tow force that water jets cannot,” said Tom Bein, Maritime’s principal engineer and project manager. “Their propulsion efficiency is higher.”
The second Carderock version, called the high-speed variant, is equipped with hydrofoils — small wings suspended from the boat’s hull by stanchions — that lift the 35-foot boat’s hull out of the water, enabling it to move at high speeds without the substantial drag caused by the friction of the water against the hull. The hydrofoils retract for operations in shallow water and at low speeds. The hydrofoils enable the boat to reach speeds of 35 knots or greater, providing a stable platform for such operations as gunnery and force protection, the mission of guarding ships and such facilities as ports, harbors and oil terminals.
Disadvantages of the hydrofoil variant include increased complexity and weight, lower endurance and deeper draft when not riding on its foils. An advantage, said Sokol, is that the stability of the hydrofoil means less shaking of the mission payloads. He said the hydrofoil variant will be able to operate in sea state 4, with waves of 6-7.5 feet.
The two Carderock USVs use the same model of diesel engine and drive train, and can be transported by a C-5 or C-17 cargo aircraft.
Bein said endurance is a chief advantage of USVs. Being unmanned, they can be deployed for long periods without regard to human limitations.
Later this year, the two Carderock USV types will go through launch and recovery demonstrations from the Navy’s Sea Fighter experimental ship, which is surrogate in sea trials for the Littoral Combat Ship. Sokol said the Navy would be testing the High-Tow Force USV in support of mine warfare for the next year, possibly longer. The hydrofoil version will be tested with other potential mission packages, which he declined to specify.
RHIBs have played an important role in the development of USVs in general and as surrogates for testing the mission packages for the Littoral Combat Ship.
“Our current [antisubmarine warfare USV] advanced development models use 11-meter RHIBs as the baseline hull,” Hutchens said. “We continue to evaluate the use of RHIBs for various roles.”
One RHIB-based USV project, the Spartan Advanced Concept Technology Demonstration, which began in 2000, has been the workhorse for testing USVs and sensors, weapons, and control systems. The $45 million Spartan project was designed to “develop a warfighting capability rapidly” and “transition the technology into the Navy,” according to Vittorio Ricci, director of Sensor and Sonar Systems Science and Technology at the Naval Undersea Warfare Center in Newport, R.I.
During the Spartan project, sensor and weapon packages for antisubmarine warfare, mine warfare and force protection were fitted into several RHIBs and evaluated. For example, with the assistance of Northrop Grumman Electronic Systems in Baltimore, the AQS-24 side-scanning minehunting sonar, designed to be towed by a helicopter, was fitted to a RHIB with a towing winch. Another RHIB was equipped with a dipping sonar for antisubmarine search. A third was armed with a .50-caliber machine gun for countering small boats and electro-optical sensors.
The Navy is awaiting the results of a set of trials of the Spartan systems conducted with Singapore off the coast of Southern California in January and February. Further antisubmarine tests are scheduled this summer with France.
Although the Littoral Combat Ship program is the main beneficiary of the Spartan project, existing ships also may eventually operate armed unmanned RHIBs in the antiterrorist force protection role.
This summer, the Navy and Coast Guard will take a look at the Protector, a USV designed for force protection and developed by Rafael Armament Development Authority Ltd., headquartered in Haifa, Israel.
Demonstrations on both U.S. coasts will be conducted by BAE Systems and Lockheed Martin, which have teamed to market the Protector to U.S. forces. The navies of Israel and Singapore already have procured the boat.
Designed for launch from a manned ship, the Protector is a 9-meter USV armed with a stabilized, 7.62mm Mini-Typhoon rapid-fire machine gun, a Toplite electro-optical/infrared sensor suite and a laser designator for targeting. Linked with a command-and-control system to a mother ship or a shore-based command center, the Protector is designed to be stationed in a harbor.
An evolution of a 9-meter RHIB, the Protector features an aluminum hull with foam on the outside for additional stability. A single diesel engine drives water jets that propel the boat to speeds of 40 knots.
A single control station can control one Protector USV.
“Rafael is working on a next-generation design to control multiple USVs from a single control station,” said Steve Kelly, director of naval systems for BAE Systems.
Neither the Navy nor the Coast Guard has a stated requirement for a USV like the Protector. The demonstrations are being funded by BAE Systems and Lockheed Martin, which declined to disclose the costs of the demonstration project.
Sean Patton, senior manager for business development at Lockheed Martin Littoral Ship Systems, sees potential for the Protector “to meet possible needs from homeland security to the Littoral Combat Ship. We see Protector right now as the only proven force protector and antiterrorist mission package USV that’s out there.”
Command and Control
USV developers also are working to multiply the number of USVs that can be controlled by a single operator.
“Whereas Spartan has two operators per boat, we’re trying to get one operator for a dozen boats or a dozen underwater vehicles,” said Larry Datko, USV program manager for Northrop Grumman Electronic Systems.
Northrop is teamed with Accurate Automation Corp., Chattanooga, Tenn., in a project called Collaborative Network of Autonomous Vehicles, sponsored by the Defense Advanced Projects Research Agency.
In a separate program, Northrop and the Navy also are developing core hardware and software systems common to all boats that will be transferable to follow-on USVs and generate specifications defense contractors can use to bid in competition. The company is partnered with Accurate Automation in this effort, called the Joint Unmanned Combined Control Advanced Concept Technology Demonstration, and sponsored by the Naval Surface Warfare Center Panama City, Fla.
“We hope to expand coordination with other unmanned vehicle programs and to move from individual vehicle control to more autonomous group control,” Datko said.
Accurate Automation is outfitting its control system on a 7-meter RHIB at the Navy’s Combat Craft Division in Norfolk, Va., and is delivering a 6-meter Sentinel USV to the Space and Naval Warfare Center in San Diego for antisubmarine warfare development, according to Robert Papp, president of the company.
Datko also said the companies are developing an unmanned vehicle control system for 11-meter RHIBs used by the Naval Surface Warfare Center Dahlgren, Va., for testing new surface warfare systems, which he declined to identify.
Mirroring the industry enchantment with unmanned aerial vehicles, General Dynamics’ Myers is optimistic about the future of USVs.
“We think there is a huge growth area across the board for the Navy in USVs, with [the Littoral combat Ship] and outside, too,” he said.
Northrop Grumman’s Datko agrees.
“The Navy is coming to terms with what its long-range plan is going to be with its USV roadmap,” he said. “Up until now it’s been a lot of these [Advanced Concept Technology Demonstration]-type things to prove concepts. Full-scale production is yet to come, but we’d like to continue to be at the center of that effort.”