Electric Warship Heralds Evolution in Weapon Technologies

By HUNTER C. KEETER
Associate Editor

When the U.S. Navy’s first integrated power system (IPS)/electric drive warship arrives in 2011 as the DD(X), the service will mark a technological breakthrough that not only signals a new era for naval engineering, but provides huge amounts of electrical power for uses once considered fanciful, such as free electron lasers, high-powered microwaves and electromagnetic rail guns.

Capt. Roger D. McGinnis, director of the Navy’s directed energy and electric weapons program office, said that while the “lethality mechanisms” of high energy weapons are classified, “Our bottom line is that if we can put millions of joules of energy onto a target, something will happen.”

In an interview with Sea Power, McGinnis described a variety of effects from these weapons, including “the burning and blinding of an optical system, or cutting an [airplane’s] wing off, or causing a fire that results in an explosion.”

DD(X) is in development by the Navy, Northrop Grumman Ship Systems, General Dynamics Bath Iron Works, Raytheon, Lockheed Martin and other firms. When the new ship arrives in service it will be armed with very advanced, but conventional weaponry, including two United Defense 155mm Advanced Gun System cannons and an 80-cell vertical launch system for various guided missiles. But these systems are stepping stones to greater capabilities, according to Michael Collins, Navy IPS/electric drive program manager. “This technology opens the door” to advanced weapons, he said.

In January 2000, then-Secretary of the Navy Richard J. Danzig — now chairman of the board at the Center for Strategic and Budgetary Assessments, a Washington, D.C., think tank — announced the Navy would commit to IPS/electric drive and associated technologies for the next generation of surface warfare vessels.

Danzig’s commitment may influence the submarine and aircraft carrier communities as well, if prominent leaders, such as the director of Navy Nuclear Propulsion, Adm. Frank L. Bowman, have their way. So far, however, the nuclear Navy, with its own approaches to power conversion and distribution, has not embraced the DD(X)-type IPS/electric drive model.

Evolutionary Improvement

An IPS/electric drive system takes raw power generated by engines (also referred to as prime movers), and converts it to electricity, which can be stored by devices such as flywheels or capacitors. The electrical power can be distributed wherever it is needed on the ship, for example, to weapons or sensors, or to electric motors which drive propellers.

That is an evolutionary improvement over present ship designs. Aboard a modern Arleigh Burke-class destroyer, four main gas turbines are coupled in pairs to huge reduction gears, providing power for propulsion. This power is not accessible for any other function. Three additional gas turbine engines are used to power an Arleigh Burke-class destroyer’s generator set, delivering a total output of about 7.5 megawatts of electricity for the ship’s systems.

By contrast, the destroyer-class IPS/electric drive would have four prime movers, which are coupled through generators to an electrical power conversion and distribution system, and to electric motors used for propelling the ship through the water. The IPS/electric drive is capable of providing 10 times the electrical output.

Advanced weapon technologies may one day take advantage of surplus electricity aboard ships, including free electron lasers, high-powered microwaves and electromagnetic rail guns. The first two are directed-energy systems — directing photons in the case of the laser, or radio frequency energy in the case of the microwave — to damage or disrupt a target with variable intensity. The rail gun concept would use electricity and magnetic fields to accelerate a projectile, which attacks a target in much the same way as conventional artillery, though with far greater kinetic energy.

IPS/electric drive has set the stage for these advanced weapon technologies, but additional laboratory work and investment are required. According to Fred Beach, a program manager in McGinnis’ office, advanced electrical weapons are not going to “cost a few million dollars and be developed overnight. These technologies require an investment of $30 million to $50 million over several years.”

Potentially, the payoff for the investment is huge. In the case of laser weapons, the lethal effect arrives at a target literally at the speed of light. So today’s challenge of developing fire-control solutions — plotting a target’s speed, maneuver and countermeasures against the capabilities of the firing platform’s sensors and weapons — could be a thing of the past for strike-group air defense.

“Now all we have to worry about is dwell time: how long do we want to hold the beam on the target to get the desired effect?” Beach said. That fact is particularly compelling to the Navy leadership struggling with the increasing threat from proliferating antiship cruise-missile technology.

While powerful lasers are not based on new technologies, their application aboard ship remains in uncharted waters. The Navy was first to produce a high-energy laser — the 1970s-era

MIRACL located at White Sands Missile Range, N.M. MIRACL is a megawatt-class chemical laser with two serious shortcomings — it produces poisonous fumes and lases at infrared wavelengths, which are neutralized by the maritime atmosphere.

Electrically powered free-electron lasers may be tuned to frequencies most effective for operating at sea. The Office of Naval Research is funding development of a free electron laser at the Energy Department’s Jefferson Laboratory in Newport News, Va. By changing frequencies, free electron lasers could perform different functions, from target designation to attack. Additionally, the ship’s crew could use the laser emitter tubes — essentially powerful telescopes — as high-resolution electro-optical sensors, for target identification and classification.

Other types of high-energy weaponry may appear sooner than lasers.

Ships could be equipped with high-powered microwave devices, such as those being developed by Marine Corps Col. David P. Karcher Jr.’s Joint Non-Lethal Weapons Directorate. Karcher’s command is working with the Air Force on a product called the Active Denial System, which is capable of causing pain that can be scaled up from mild heat to an extreme burning sensation. The military wants the Active Denial System to use as a force protection device.

Over the next year, the Active Denial System will be packaged and tested in a vehicle configuration aboard a military Humvee. It could officially be deployed after 2005. A shipboard application could follow — perhaps useful in future scenarios such as the October 2000 attack on the destroyer USS Cole, when a terrorist bomb killed 17 sailors and crippled the ship.

McGinnis’ office also is working on a rail gun that could draw powerful pulses of electricity from a modified IPS/electric drive system to launch projectiles. Propellant is not needed in the rail gun concept because clean electricity launches each round down a rail or through a magnetic coil. The speed with which a rail gun’s projectiles travel may deliver thousands of times the kinetic force of a conventional artillery shell, making explosive warheads unnecessary.

Chief of Naval Operations Adm. Vern Clark, told a Navy League of the United States Sea-Air-Space luncheon audience April 8: “the rail gun is in our mind and we are investing in it.”

Make A Real Difference

While rail guns, high-powered microwaves and lasers are unlikely to replace conventional munitions outright, McGinnis noted that these technologies would likely co-exist on the ships of the future. “If there is no danger of collateral damage and the objective is to blow a target up, then conventional weapons do a great job,” he said.

Once operational, however, directed energy weapons could make a real difference for the Navy. McGinnis noted that, despite the range and line-of-sight limitations that make them unsuited for long-range strike, lasers deliver very fine beams that can be precisely controlled. Lasers could be called upon in cases with a high probability of collateral damage, for example, if a small enemy vessel attempts to hide among friendly vessels or other non-combatants.

With the potential to cause horrific damage against a target exposed to full power emissions, directed energy weapons could also emit power on low settings to drive targets away from a conflict area, with no loss of life.

“The military likes having the option that does not cause collateral damage. That lets us engage units that are close to friendly forces and where we don’t have to kill, but can simply make the enemy go away,” McGinnis said.

Whatever investment decisions are made for weapons the next several years, the Navy already is engineering the potential these technologies require, according to Collins and his IPS/electric drive team for DD(X).

That team is helping to make practical what Danzig and other Navy leaders, such as Rear Adm. Charles S. Hamilton II, program executive officer for ships, have said: that the acquisition of a IPS/electric drive is like “the shift from sail to steam.”

On Oct. 29, 1814, the first U.S. steam-powered warship, the 32-gun Demologos, designed by Robert Fulton, was launched in New York. The Demologos — scuttled when its magazine exploded in 1829 — contrasted sharply with the most advanced sail frigates of its day, and though under-appreciated by the naval establishment, lit the way to the future.

It took almost two generations for James Watt’s practical improvements on Savery’s and Newcomen’s steam engine in 1769 to inspire the first steam-powered warship. IPS/electric drive, itself not a new concept, may have come of age, according to Philip A. Dur, president of Northrop Grumman Ship Systems.

“The beauty of it is that we will have this ‘power surplus’ on the ship so that we develop the weapon suites on these ships spirally,” he said. “The power surplus is integral to the advantage we have in this ship.”

Cruise ships have long employed electric drive because it is less costly to operate than more conventional propulsion systems. In a conventional propulsion system, the engines are accelerated or decelerated to increase or decrease speed. IPS/electric drive de-couples the prime mover from the propeller shaft. Because gas turbines operate more efficiently at higher shaft revolutions, prime movers in an IPS/electric drive can be revved up to their most efficient level of operation and remain there. Electric motors are used to change the ship’s propeller speed.

Fuel economy is a key reason why the Navy is investing in IPS/electric drive.

The U.S. Navy experimented with electric drive in 1911 with the ex-USS Jupiter — converted in 1913 as USS Langley, the first aircraft carrier. Other military vessels are operating today with forms of electric drive. For example, the U.S. Coast Guard Cutter Healy, built in 1993, is an electric drive vessel powered by diesel prime movers. The British Royal Navy’s Type-23, new Type-45 and new aircraft carrier programs are designed with IPS/electric drive-type systems in mind.

Development Continues

The Naval Surface Warfare Center, Carderock Division’s, Ship Systems Engineering Station in Philadelphia has been putting Danzig’s vision for a new, state-of-the art IPS/electric drive design into action.

The engineering development model for the DD(X) IPS/electric drive is to be assembled there by April 2005. Testing of the model is to continue from June to September 2005. DRS and General Atomics have developed permanent magnet motor technologies the Navy will evaluate at Philadelphia.

Additionally, other approaches — such as Alstom’s advanced induction motor, American Superconductor’s high-temperature superconductor and General Atomics’ superconducting DC homopolar motor — have attracted naval interest.

Northrop Grumman Ship Systems and its partners are working with the Navy under a $2.9 billion contract for DD(X) that includes the design, manufacture and test of 10 engineering development models.

IPS/electric drive is one of those models. The system will provide 78 megawatts of power to produce electricity for propulsion and all of the ship’s systems, including advanced sensors and weapons.

Though significant technological and funding challenges remain, additional available electrical power in the DD(X) design has already made it possible for the Navy to embrace and re-invigorate its programs for advanced weapon and sensor technologies.

As Collins put it: “If you back off on how much electric power you have on board [new ship designs], then you are almost backing away from the future.”