U.S. Navy efforts towards development of

future naval weapons and integration into an

All Electric Warship (AEW)

Lynn J. Petersen

United States Navy Michael Ziv

United States Navy

Daniel P. Burns

United States Navy Tim Q. Dinh

United States Navy

Peter E. Malek

Herren Associates, Inc., USA

SYNOPSIS

The All Electric Warship (AEW) is the ideal platform to provide the needed power to support these advanced

weapons and is, by definition, an engine employed as a weapon. The weapons systems technologies of the future

demand a never before rivaled level of power, cooling, and energy storage. Additionally, the various weapon

systems will compete for the installed power and energy simultaneously, hence, demanding a power and energy

management system to effectively provide the right power to the right load at the right time. Therefore, the AEW

must be built and equipped with the necessary energy architecture and sufficiently robust control systems to meet the

power and energy demands of these weapons systems. Lastly, the AEW must be designed and built to incorporate

flexible and modular open architecture standards to facilitate the incorporation of high power and energy demand

weapons systems into future platforms.

INTRODUCTION

The 2010 Quadrennial Defense Review (QDR) issued by former Secretary of Defense (SECDEF) Robert Gates, and 2011 National

Military Strategy issued by U.S. Navy Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff (CJCS), emphasizes the ongoing

shifts in power and increasing interdependencies internationally, which indicate a strategic inflection point of a complex and

uncertain security landscape where the pace of the threat continues to accelerate. This requires America‟s foreign policy to employ

an adaptive approach to maintain a forward presence and a global force for good. The changing distribution of power suggests an

adaptation to a "multi-nodal" world characterized more by shifting, interest-driven coalitions based on diplomatic, technological,

military, and economic power, than by rigid security competition between opposing blocs (NMS 2010). As outlined by Admiral

Mullen in the National Military Strategy issued 8 February 2011:

“Both our Nation and military will face increased budget pressures and we cannot assume an increase in the defense

budget…We must continue to maintain our margin of technological superiority and ensure our Nation’s industrial

base is able to field the capabilities and capacity necessary for our forces to succeed in any contingency. At the same

time, we will pursue deliberate acquisition process improvements and selective force modernization with the cost

effective introduction of new equipment and technology.”

Authors’ Biographies Captain Lynn J. Petersen is assigned to the Naval Sea Systems Command (NAVSEA 05Z) and is the Deputy Director of the Electric

Ships Office (PMS 320) under the U.S. Navy Department Program Executive Office for Ships in Washington, D.C. Captain Petersen

holds a Bachelor of Science in Mathematics from the United States Naval Academy, and a Master‟s in Mechanical Engineering from

the Naval Post Graduate School. He is a member of ASNE and IEEE.

Captain Michael Ziv is assigned to the Naval Sea Systems Command (NAVSEA 05T) and serves as the Program Manager for the

Electromagnetic Rail Gun Program (NAVSEA, PMS 405) and Deputy Program Manager for EMRG INP (ONR-352). Captain Ziv

holds a Naval Engineer degree and Master‟s in Mechanical Engineering from MIT.

Captain Daniel P. Burns is assigned as the ASN RDA – SSP Naval Systems Engineering Chair at the Naval Postgraduate School

(NPS). He is the former Military & acting dean of the Graduate School of Engineering & Applied Sciences (GSEAS) at NPS. He

holds a Bachelor of Science in Resources Management from the US Naval Academy and a Master of Science in Technical

Intelligence from NPS. He is a member of the Laser Operations Scoring Committee for the Pebble Beach Pro-Am tournament.

Tim Q. Dinh is the Integration Engineer of NAVSEA PMS 405; his previous experience from the private sector includes leading

multiple projects in the fields of Radar, Electronic Warfare, Remote Sensing, and Tactical/Link Communications. Tim holds a B.Sc.

in Electrical Engineering (University of Maryland, College Park), a M.Sc. in Applied Physics, and a M.Sc. in Computer Science

(Johns Hopkins University); he is currently pursuing a M.Sc. in Electrical Engineering, and a M.Sc. in Applied & Computational

Mathematics (Johns Hopkins University). Tim is a member of IEEE, APS, and DEPS.

Peter E. Malek is a Senior Associate with Herren Associates, a Washington, D.C. based firm, leading a team of engineering and

management consultants who serve a broad range of clients across the federal sector. Mr. Malek holds a Bachelor of Science in

Decision Sciences and Management Information Systems from the George Mason University, a Master‟s in Systems Engineering

from the George Washington University. Mr. Malek is a lean six sigma black belt practitioner, a member of the American Society

for Naval Engineers (ASNE) and has authored and co-authored several industry studies, presentations, and white papers presented at

government and industry symposia.

As the threats developed by our adversaries continue to evolve and become increasingly more sophisticated, so too does our

need to counter those threats. The Next Navy must be equipped with the necessary installed power, energy, and control

systems needed to effectively and efficiently align the right power to the right mission load at the right time. Considering the

growing challenges, and goal of a future state of an AEW, this paper addresses the fundamental questions identified in Figure

1, proposing a disciplined process improvement framework consistent with five core disciplines of Define, Measure, Explore,

Develop, and Integrate, to deliver the necessary weapons systems enabled by Integrated Power Systems (IPS). Specifically,

this paper will explore candidate technologies in the acquisition process and integrated architectures and controls that provide

a foundation for revolutionizing the current and future naval fleet by describing the U.S. Navy‟s development efforts to date

and roadmap to implement the needed architecture for delivering safe, reliable and effective electric power support for

weapons systems technologies, including current design, development, test challenges, and employment of the AEW.

Fig 1 DMEDI Technology Maturity / Acquisition Framework

DEFINE: PACING THE PROJECTED THREAT INTO THE 21ST

CENTURY

Maritime forces in the twenty-first century will confront a formidable array of threats. The U.S. and allied navies will face

unprecedented weapons systems highly asymmetric in nature, and anti-access / area-denial (A2AD) in focus. These weapon systems,

coupled with swarming tactics, represent relatively inexpensive challenge for U.S. naval forces in the contest for local control of the

sea.

As outlined in Figure 2 below by Admiral Gary Roughead, the Chief of Naval Operations in his Navy League speech, 26 August

2010 in San Diego:

“With the juxtaposition of the limited defense budgets against a growing demand for naval power in mind we must recast our

approach to procurement and focus efforts in developing affordable capabilities and capacity.”

Fig 2 Strategic Alignment to Combat the Evolving Threat

The reality of the last two decades has been the increasing capability of weapon systems developed specifically to kill modern surface

warships. The current supersonic sea skimming Anti-Ship Cruise Missile (ASCM) threats will soon be supplemented by Anti Ship

Ballistic Missiles (ASBM) systems and weaponized Unmanned Air Vehicles (UAV).

The evolution of ASCM threats has focused on enhanced survivability and increased probability of kill, and will continue in the

following areas:

Sea-skimming attack capabilities present challenges for all naval air and missile defense systems, compressing the time

available for defensive fires.

Increasing maneuverability and supersonic terminal speed extract heavy tolls on the defense systems; warm tactics

exacerbate this problem.

Increased ASCM ranges turn previously-opened access into choke points.

Reduction of radar signatures associated with sea-skimming profiles is a challenging task even for a good pulse Doppler

radar.

Multimode seekers/anti-jamming capabilities enhance the probability of kill

ASBMs are new threats to the U.S. Navy. Compared to ASCM attacks, ASBM attacks offer more warning time. On the other hand,

ASBMs are significantly faster, making them more challenging targets. While ASCMs can still be engaged by close-in gun systems

or lasers, ASBMs are too difficult a target for such terminal defenses. Their speed alone requires exceptionally high tracking rate

performance for an effective intercept. At longer ranges, it is difficult to counter an ASBM due to its high re-entry velocity.

Weaponized UAVs are much slower and less maneuverable than ASCMs. However, they are less expensive to acquire and operate,

thus providing a much greater swarming capability. UAVs also have flexibility in coordinated attacks and mid-course target

acquisition. For UAVs, their strength is in the number; they are used to deplete high-value but numerically-limited missiles.

As stated by the U.S. Navy R&D chief Rear Admiral Nevin Carr, 28 June 2011, in a future weapons technology article: "We're fast

approaching the limits of our ability to hit maneuvering pieces of metal in the sky with other maneuvering pieces of metal." How

soon credible defensive technologies can be deployed remains to be seen; the answer may be Lasers and Railgun.

The high cost of modern warships makes an ASCM extremely cost effective. The relatively low cost of multiple UAVs, ASCMs, or

ASBMs against the high cost of a single surface combatant and limited magazines makes it asymmetric against the defenders. With a

low cost per shot and deep magazines, lasers and railguns will potentially help turn asymmetric warfare against the attacker.

High Energy Lasers (HEL)

Compared to existing ship self-defense systems, such as missiles and guns, lasers could provide the U.S. Navy surface ships with a

more cost effective means of countering certain surface, air, and ballistic missile targets. Ships equipped with a combination of lasers

and existing self-defense systems might be able to defend themselves more effectively against a range of such targets. Equipping

surface combatants with lasers could lead to changes in naval tactics, ship design, and procurement plans for ship-based weapons,

bringing about a technological shift for the U.S. Navy, a “game changer,” comparable to the advent of shipboard missiles in the

1950s.

In general, laser weapons enable delivery of scalable levels of energy at both tactically and strategically relevant distances enabling

the accomplishment of new missions and generating entirely new classes of effects during naval engagements and on the battlefield.

They also offer unique solutions to many of the most serious threats and enable safer accomplishment of hazardous missions.

Compared to traditional weapons, laser weapons offer significant benefits including: gradual or controlled lethality (combined non-

lethal and lethal capabilities in one system), long-range force application capabilities, low per-shot cost, deep magazine, fast speed-

of-light engagement times, ability to counter radically-maneuvering targets, precision engagement and low collateral damage, and

significantly smaller logistics footprints than non-DE weapon systems.

Laser weapons destroy a target either by heating the target surface to the weakening point and causing it to fail under operating stress,

or by burning through the skin to destroy underlying critical components and subsystems. Laser weapons are also used to attack

energetic material in a target and cause low-order detonation. They can be used effectively against a multitude of sensors including:

an in-band soft kill, where sensors experience a reversible “flash-blinding”; an in-band hard kill, where sensors experience a non-

reversible “flash-blinding”; and an out-of-band hard kill where the sensors are physically destroyed by the deposited energy.

Department of Defense (DOD) development work on high-energy military lasers has been underway for decades and has reached the

point where lasers capable of countering certain surface and air targets at ranges of about a mile could be made ready for installation

on U.S. Navy surface ships over the next few years. More powerful shipboard lasers, which could become ready for installation in

subsequent years, could provide U.S. Navy surface ships with an ability to counter a wider range of surface and air targets at ranges

of up to about 10 miles [O‟Rourke 2011]. These more powerful lasers might, among other things, provide U.S. Navy surface ships

with a terminal-defense capability against ASBMs.

The U.S. Navy and DOD are developing three principal types of lasers for potential use on U.S. Navy surface ships, fiber solid state

Lasers (SSLs), slab SSLs, and Free Electron Lasers (FELs). The U.S. Navy‟s fiber SSL prototype demonstrator is called the Laser

Weapon System (LaWS). Among DOD‟s multiple efforts to develop slab SSLs for military use is the Maritime Laser Demonstration

(MLD), the U.S. Navy has developed a lower-power FEL prototype and is now developing a prototype with scaled-up power. These

lasers differ in terms of their relative merits as potential shipboard weapons.

Figure 3 below shows a long-term laser development roadmap for the Directed Energy and Electric Weapons (DE&EW) program.

Goals must include overcoming socialization issues and assessing the utility of, developing and eventually integrating a megawatt-

class hard-kill laser weapon system into a complex shipboard environment. This represents the U.S. Navy surface fleet‟s generalized

vision for shipboard lasers that envisions deploying lasers into the “Navy Now”, the “Next Navy” (i.e., the Navy that will be

produced by current shipbuilding programs), and the “Navy After Next” (i.e., the Navy that will be produced by future shipbuilding

programs). This generalized vision can be summarized as follows:

Navy Now: A 60-100 kW Solid-State laser with potential Initial Operating Capability (IOC) around FY2017. It provides

short-range operations against targets such as EO sensors, small boats, UAVs, RAM, and man-portable air defense systems

(or MANPADs, shoulder-fired surface-to-air missiles).

Next Navy: A 300-500 kW Solid-State laser with a BQ of approximately 2 and use of adaptive optics. It provides

extended-range operations against targets such as EO sensors, small boats, UAVs, RAM, and MANPADs, as well as

ASCMs that are flying on a crossing path (rather than at the ship).

Navy After Next: An MW-class laser. It provides self-defense operations against transonic and supersonic / highly

maneuverable ASCMs, and ASBMs.

Fig 3 HEL Roadmap and Technology Insertion

U.S. Navy Electromagnetic Rail Gun (EMRG/Railgun)

The Railgun is an ONR Innovative Naval Prototype (INP) initiative to develop mission-critical technologies and aid in the critical

transition from S&T to a program of record. An INP supports the development of technologies considered “disruptive,” in other

words, a technology that is high risk, causes a departure from an established requirement or unique concept of operations (CONOPS).

The primary goal of the INP is to reduce risk in acquisition. As shown in Figure 4, the railgun INP will be executed in two phases.

INP Phase I is currently focused on technology risk mitigation of key railgun projectile components and the development of a 32-MJ

launcher and pulsed power system. INP Phase II will focus on the development of prototype system components, continued

technology development for the projectile to achieve a tactical muzzle energy level, and a long-range component validation

demonstration to achieve a Technology Readiness Level (TRL) of 5 by the completion of INP Phase II in 2017.

Fig 4 Railgun – Technology Development Roadmap

Additionally, NAVSEA PMS-405 (Directed Energy and Electric Weapon Group) will be conducting a parallel Advanced Component

Development and Prototype (ACD&P) phase commencing in 2014. This ACD&P Phase will culminate with a transition to an ACAT

1 program of record at Milestone B in the 2019 timeframe. The main focus of the ACD&P is to develop and demonstrate a 20 to 40-

MJ prototype weapon system at sea or at a land-based facility at a TRL of 6. This will minimize system integration risk to the extent

possible prior to program initiation.

Figure 5 below shows the planned Naval Surface Fire Support (NSFS) capabilities of the railgun at the 64 MJ muzzle energy level,

with an indirect firing range of between 50 and 250 NM which will be varied mainly by adjusting the firing angle, with a peak

altitude of approximately 800,000 feet at 50 NM and approximately 500,000 feet at 250 NM. Muzzle velocity will be approximately

2.5km/sec (or about Mach 7.5) with an impact velocity of about Mach 5.0. During its flight trajectory, the projectile spends

approximately 5 minutes of its 6 minute flight above the sensible atmosphere (greater than 100,000 feet) thus simplifying airspace de-

confliction. The anticipated range of the railgun at 64 MJ (250 NM) exceeds the anticipated range of all current or near term

projectiles and is equal to the future assault range of the U.S. Marine Corps (USMC) MV-22. This capability will allow the railgun to

complement USMC MV-22 tactical air assets in high operational tempo engagements and may be used to provide support for forces

ashore from an off-shore at-sea platform in the event that particular operational circumstances do not support placing tactical air or

ground-based fire support assets in harms‟ way. Even at half the full tactical energy level of 32 MJ, the railgun will have an

anticipated range of approximately 110 NM which is equal to the current USMC “ship to objective maneuver” (STOM) distance of

200 km (about 110 NM).

Fig 5 Railgun – 64 MJ Capabilities

The railgun will accomplish these capabilities as a pure kinetic energy round without the use of any propellants or explosives. By

eliminating explosive elements from the logistics train, the railgun will provide the future warship with the ability to carry nearly 10

times the current number of on-board rounds within the same space as current magazines, extending time on station and improving

the total volume of fires that can be provided from the sea. Other benefits of Railgun kinetic energy projectiles include precision

strike with minimal collateral damage, a simplified logistics tail, reduction in weight (typically required for magazine armor),

firefighting systems, thermal insulation, reduced life cycle cost, and a significant level of flexibility provided to the U.S. Navy

warship designer not possible with conventional explosive munitions. Figure 6 below provides an image captured when ONR

achieved a milestone on December 10, 2010 by successfully conducting a world-record 33 MJ shot of the railgun at the Naval

Surface Warfare Center Dahlgren Division (NSWCDD).

Fig 6 Railgun – world-record 33MJ shot

The railgun provides missile ranges at bullet prices and will provide persistent, volume and precision all weather fires. Because the

projectiles do not have explosives or propellants, more rounds can be stored in a typical magazine than is possible using explosive

type projectiles. Safety of shipboard personnel is also dramatically improved by eliminating the potential of sympathetic detonation

in the event of enemy attack. The use of non-explosive projectiles also provides significant benefits by eliminating the risks

associated with unexploded ordnance (UXO).

The railgun provides a truly unique capability for volume fire at long range and an ability to engage targets in a high-threat

environment. The use of a railgun enables rapid engagement of a wide range of target sets, while freeing up tactical air (TACAIR)

and cruise missiles to concentrate on high-value targets that are not likely to be engaged effectively with first-generation railgun

weapon systems (e.g., moving or mobile targets). Also, the high-altitude flight profile and steep attack angle of railgun projectiles

provide greater flexibility to attack targets effectively in mountainous terrain by using ordnance that are practically invulnerable to

enemy counterattack. It is impractical for the enemy to engage railgun projectiles as they descend into the target area. The projectile‟s

small size and extremely high velocity present a very difficult target and an unfavorable geometry to enemy defensive systems. In

addition, the large number of railgun projectiles will likely overwhelm any enemy defensive system. Future railgun system

development could enable an unprecedented capability to place rounds in a pre-determined pattern to dramatically increased target

lethality over a wide range of potential threats.

Successful use and utility of these lethal, high energy electric weapon systems depends upon the hull, mechanical and electrical

(HM&E) systems to effectively and efficiently provide the power and energy to these weapons when they need the power and

energy. Such a system is known as an Integrated Power System (IPS). While many of these systems, such as the railgun or FEL, are

more than a decade away from introduction, other weapon and sensor systems incorporating high power, such as the LaWS/MLD and

Air and Missile Defense Radar (AMDR) are more mature technologies and therefore nearer term solutions. These systems draw

higher power than the systems they replace and need to be properly integrated with the ship‟s power system.

The Integrated Power System (IPS) Advantage

The IPS provides total ship electric power to mission loads including weapons, sensors, and electric propulsion. It accomplishes this

power delivery through power generation, distribution, conversion, storage, and control. In the commercial marine industry, IPS is

known as the „Power Station‟ concept. The Royal Navy refers to this architecture as Integrated Full Electric Propulsion (IFEP).

The flexibility of electric power transmission allows power generation modules with various power ratings to be connected to

propulsion loads and ship service in any arrangement that supports the ships mission at the lowest cost over the Expected Service

Life (ESL) or lifecycle. With advancements in solid state power electronics, power dense motor drives, and rapid computation

employing sophisticated control systems, the Navy‟s ships will enjoy the benefits of electrical integration as shown by Figure 7

below. Significant fuel savings are anticipated through this integrated architecture because lower power, power generation modules

known as Auxiliary Turbine Generators (ATG‟s) can operate the ship when the ship is employing a lower energy posture, without

having to operate the higher power Main Turbine Generators (MTG‟s).

Fig 7 Shipboard Power and Propulsion Systems

The adoption of the IPS architecture began for the U.S. Navy with the USNS Lewis and Clark (T-AKE 1) dry cargo ships and the

USS Zumwalt class (DDG-1000) Destroyer. The USS Makin Island (LHD-8) with its Auxiliary Propulsion System (APS) represents

a partially integrated power system. To date, all of these systems have involved commercially derived naval technologies. To

achieve the power densities demanded by modern warships, equipment that is more power dense than commercial equipment is

needed. PMS 320 Electric Ships Office (ESO) has been chartered with developing these more power dense shipboard power systems

for future ships.

MEASURE: INCREASING INSTALLED ELECTRIC POWER

The amount of electrical power used on-board warships has grown exponentially over the past century (reference Figure 8). Initially,

electric lighting systems were installed to replace the oil lamps of the day. Gradually, the use of electricity aboard ships has expanded

in a similar fashion to what society has experienced in our own homes (Sturtevant 2011). Today, virtually every system aboard a

modern warship depends upon the electricity generated, distributed, converted and stored aboard that ship in order to efficiently and

effectively function, making the electric power system on a ship the most critical support system installed. The century-long trend in

power growth is not expected to end anytime soon.

Fig 8 Warfighting Needs Drive Power Systems

Figure 8 above provides a historical perspective of the emergence of weapons systems from the time period of only guns, to systems

of the near future that include guns, missiles, and DE&EW weapons. The power and energy associated with these systems will

surpass the installed power and energy of the ships propulsion system. Installing the power generation needed for all of the mission

power loads will significantly drive the requirement for hull displacement, length and width of the ship, which in turn drives the cost

of the ship, resulting in an “Affordability Gap” as indicated in the figure above. IPS addresses this gap affordably to meet the

mission power demands and achieve mission capability.

Interesting to note, the U.S. Navy is not the only navy in the world to be committed to furthering electric drive in their ship inventory.

Several countries as listed on Figure 9 below have been committed to developing and delivering some form of electric drive from

HED to IPS.

Fig 9 Other Navy‟s Electric Drive Initiatives

Navy international partners have gained experience with integrated architectures. For example, the Royal Navy‟s acquisition of the

Type 45 Destroyer with an IPS and the Type 23 Frigate powered by the Combined Diesel-Electric and Gas Turbine (CODLAG)

architecture. Similarly, the U.S. Navy gained IPS experience with the acquisition of the Lewis and Clark Class (T-AKE) Dry Cargo /

Ammunition Ship and the Combined Diesel-Electric or Gas Turbine (CODLOG) also known as hybrid gas-turbine-electric drive

aboard the USS MAKIN ISLAND (LHD 8) Amphibious Assault Ship, which is a partially integrated architecture.

EXPLORE: CURRENT TECHNOLOGY DESIGN, DEVELOPMENT AND TEST CHALLENGES

If the U.S. Navy waits until the requirement materializes for the AEW, it will be too late to develop, mature, and ensure the

technology readiness needed to meet the demands. As shown in Figure 10, depending upon the acquisition program (surface ship,

aircraft carrier, or submarine), a significant amount of time is needed to make the technology ready, if it is not already available, to

bring it to the right technology readiness level to meet consideration for ship insertion. Figure 11 identifies a „„Design and

Technology Selection‟‟ milestone occurring along the ship acquisition schedule after concept design. This design and technology

selection occurs simultaneously 1–2 years before milestone B at the conclusion of the preliminary design and before the start of

contract design where the ship specifications are developed (Petersen 2009).

In order for emerging systems to be considered for selection, technologies must achieve a Technology Readiness Level of 6 or above.

ONR has had a dedicated Science and Technology (S&T) program focused on ensuring the availability of demonstrated technologies

ready for advanced development and further maturation. Ranging from basic Science and Technology (S&T), discovery and

invention through applied research to demonstration (future naval capabilities [FNC], swampworks, and innovative naval prototype

systems [INPS]), ONR continues to be committed in advancing S&T to match „requirements pull‟‟ with „„technology push.‟‟ These

committed investments, while some are focused on Navy After Next capabilities, have resulted and will result in technology products

needed to meet current and future fleet demands.

Fig 10 Mission Systems: Increasing Electrical Power Demands Fig 11 Challenge of New Technology

DEVELOP: NEXT GENERATION INTEGRATED POWER SYSTEMS, PLATFORMS AND

ARCHITECTURES THAT SUPPORT AEW TECHNOLOGIES

Today, as a result of technology investments, we have three examples in our U.S. Navy and Military Sealift Command (MSC): USS

Makin Island (LHD-8), the USNS Lewis and Clark (TAKE- 1) class of ships, and USS Zumwalt (DDG-1000) which is currently

being built. Figure 12 depicts these three platforms. Additionally, the T-AGOS ships, T-ATF 166 class, T-AGS 45, and T-ARC 7 are

also electric drive ships. The USS Makin Island (LHD-8) is the last of the Wasp Class, or LHD-1 Class of ships.

Fig 12 Today‟s Integrated Electric Ships

Completely different from its preceding hull, LHD-7, USS Iwo Jima, a steam propulsion plant, LHD-8 incorporates a combined gas

turbine and motor for propulsion and Ship Service Diesel Generator for ship electrical distribution. As the figure indicates, a

significant fuel savings (US$2.0M) was achieved through employment of a 5,000 hp induction motor which propelled the ship at

speeds up to 13 knots, and a General Electric LM2500+ gas turbine for speeds >13 knots up to full power.

Both T-AKE and DDG-1000 employ a full up IPS. The difference: T-AKE was built and installed to commercial specifications

which resulted in lower acquisition and largely anticipated lifecycle costs, and DDG-1000 IPS is being built to military

specifications. This will result in a ship total installed power of 78MW, and is expected to „„sail away‟‟ in 2015.

Energy Storage Modules (ESM)

Energy storage is a key element to accommodate the transient response of high speed generators and the quality of service (QOS) to

mission loads. Figure 13 below contains the 3 increments and functionality associated with energy storage implementation. Without

energy storage modules incorporated in the architecture, the AEW will not be realized.

Fig 13 Energy Storage Development Approach

Future combat systems such as railgun, lasers, and high power radars may require large amounts of power in short pulses. Prime

movers in general cannot respond quickly enough to support these pulse power loads without assistance from energy storage. A

typical power system for a railgun is shown in Figure 14. The Pulse Forming Network (PFN) draws power from the power system,

stores the energy in either capacitors or in a rotating machine, then delivers the energy in a short burst. The size, complexity, and

cost of the PFN will depend on how rapidly the Power Generation Modules (PGMs) can ramp up and down in delivered power.

High power, high energy storage for mobile pulsed applications is an emerging technical field. The conventional solutions have been

capacitors and rotating machines. Given the nature of the two storage systems, Navy, Army, and Air Force programs appear to be

converging on rotating machines for longer pulse applications, like the Electromagnetic Aircraft Launch System (EMALS) and less-

than-lethal weapons, and using a rotating machine to store the energy and discharge into a capacitor bank for shorter pulse

applications.

As energy storage technologies mature, opportunities exist to use the same energy storage modules to serve pulse loads and to permit

single-generator operation by providing backup power for uninterruptible and short-term interruptible loads. Engineering is also

required to ensure the power and energy demands of the pulse power interfaces do not have a dynamic behavior incompatible with

power system stability and power quality.

Fig 14 Notional Railgun Power Interface

In order to fully realize an AEW that efficiently and effectively employs multiple pulsed and continuous duty systems simultaneously

to include DE&EW weapons, AMDR and successor systems in combination with a high power propulsion plants, additional

development is needed.

INTEGRATE: MARINE AND WEAPONS SYSTEMS INTO THE ALL-ELECTRIC WARSHIP (AEW)

Our Navy‟s steam ships had a common source of „„energy‟‟ to meet both propulsion and ship service loads. This „„integration‟‟ was

lost when the Navy transitioned to internal combustion engines (e.g., DD-963, FFG-7, CG-47, and DDG-51). Propulsion loads and

ship service loads were supported from separate sources of power generation. Today, IPS brings back „„integration,‟‟ but it is

integration on the electrical side, which has resulted from advancements in solid-state power electronics, multi megawatt motor

drives and automation and control.

System integration and technology development challenges to improve efficiency and reduce fuel consumption, while balancing the

need to evaluate mission requirements for additional electrical power generation, are not insignificant. However, PMS 320 is working

across the Fleet to develop and transition innovative technologies to transform the U.S. Navy‟s energy-security posture and pace the

threats facing the Fleet over the next several decades.

Future weapon systems, such as laser technology has matured greatly over the last forty years. While the development of higher

power and more efficient devices continue to progress, the significant fact is that lasers have the demonstrated ability to destroy

missiles. Terrestrial and maritime lasers capable of delivering sufficient power for weapons applications appear to be feasible without

major technological innovations. The limitations imposed by tropospheric propagation phenomena are still undetermined, but it must

be understood that this could ultimately compromise the effectiveness of laser-based systems for air defense.

Adoption of innovative and energy efficiency enabling technologies will be required to transform the U.S. Navy‟s energy posture. As

part of achieving a desired future state of an AEW, ongoing challenges must be overcome including:

Interface Specifications. Identifying what interface specifications need to be developed in order to effectively integrate

new weapons/sensor systems in an All Electric Warship.

Power and Energy Requirements: Understanding the power and energy demand requirements of new weapons / sensors.

Taking into consideration efficiency or inefficiencies with respect to power conversion that the systems bring and then

identifying sufficient margin (service life allowance, center of gravity, etc.) aboard a ship.

Back Fit vs. Forward Fit

Identifying Future Technology Gaps: The ability to predict the future to any degree of accuracy is limited to less than a

decade. The S&T horizon however, extends beyond this time frame. As a consequence, understanding alternate potential

futures and the likelihood of future Technology Gaps is challenging and requires subject matter expertise (Doerry 2010).

Requirement Punctuality: Meeting the requirements in sufficient time to allow technology development, demonstration and

maturation to meet program schedule and operational performance.

Given the three time periods of Navy Now, Next Navy, and Navy After Next, in order to address the challenges that senior U.S. Navy

leadership is currently facing, specific U.S. Navy investments leveraging PMS 320 and the Office of Naval Research (ONR) are

already underway. Figure 15 below displays the PMS 320 Next Generation Integrated Power Systems (NGIPS) Technology

Development Roadmap (TDR) currently being updated, and Figure 16 demonstrates how PMS 320 is leveraging the TDR to work

with ONR to monitor the development and integration of the AEW but at the same time maturing products resulting from ONR

investment into advanced developments that can be inserted in the U.S. Navy via backfit or forward fit to meet ongoing challenges.

Fig 15 NGIPS Technology Development Roadmap (TDR) Fig 16 Current Now and Next Navy Opportunities

The NGIPS incorporates lessons learned from the U.S. Navy‟s efforts to date to develop and introduce IPS within an open

architecture technical and business framework. Recognizing that the appropriate affordable power system for different types of ships

may require different technologies, NGIPS categorizes applications by the required power density and Quality of Service (QOS)

requirements. QOS serves as a metric of the continuity (i.e., reliability and survivability) of the electrical power supply support and

the operation of its loads.

Medium Voltage Medium Frequency (MVMF) represents the middle of the NGIPS roadmap as shown in Figure 16 in terms of TRL

and a near term developmental schedule. With MVMF, power is generated at a fixed frequency greater than 60 Hz, but less than 400

Hz. The advantages of a MVMF AC power system include:

Increased power density over MFAC architecture. Specifically, magnetic components such as transformers, motors,

generators, and filters will be smaller and lighter than in a 60 Hz system. For example, the weight of a 240 Hz

transformer core would be about ¼ the weight of a 60 Hz transformer with all other design parameters equal.

Reducing the stack up length of PGMs by removing the gearing for direct drive of the generator.

Improved acoustic performance over 60 Hz operations. By operating at a higher frequency than 60 Hz the acoustic

absorption of vibrations is greater in seawater. At 240 Hz, the acoustical absorption is about 6.5 times greater than that

of 60 Hz, which inherently reduces the transmission of the ship‟s acoustic signature. Additionally, sound attenuation of

equipment is easier at higher frequencies.

The Medium Voltage Direct Current (MVDC) architecture represents the most long-term developmental schedule and lowest TRL of

the various NGIPS architectures. The primary difference between MVDC and Medium Voltage Alternating Current (MVAC)

systems is that instead of distributing AC power throughout the ship, the system primarily distributes DC power. At a high level, the

architecture for a MVDC power system is identical to the MVMF systems depicted in Figures 17 and 18 below.

PDM

PD

M

PD

MP

DM

PD

M

PDM PDM PDM

PDM PDM PDM PDM

PGM PGMPGM PGM

PD

M

PD

M

PMM

PMM

ZEDS

ZEDSZEDS ZEDS ZEDS

ZEDSZEDSZEDS

PGM

PGM

PGM

PGM

PD

MP

DM

PD

M

PD

MP

DM

PD

M

PD

M

IFTP

IFTPIFTP

PMM

PMM

Fig 17 MVMF (MVDC) Distribution System in ZEDS Arch. Fig 18 MVMF (MVDC) Ring Bus Distribution System with IFTP

The benefits expected from MVDC include:

Decouples prime mover rotational speed from electrical bus frequency, enabling optimization of the generator for each

type of prime mover. Allows variable speed prime mover operation to optimize efficiency. The paralleling of

generators only requires voltage matching and does not require time critical phase matching of rotating machines.

Enables operation of power conversion equipment at frequencies at an order of magnitude higher than with

conventional MVAC systems as possible with MVMF systems, resulting in smaller and lighter components.

Potential reduction in cable weight due to lack of conductor skin effect and reactive power losses.

Solid state power conversion enables much smaller fault currents than with AC systems.

Improved acoustic performance over MVAC and MVMF systems. Since there is not a common power distribution

frequency of vibrating equipment, the acoustic signature has a broader signature with fewer tonals that can be

observed in the acoustic signature of the ship.

Development of the technologies needed to comprise the Compact IPS and realize the AEW with multiple pulsed loads is not

sufficient, without careful and systematic integration of the HM&E technologies with those of the mission loads previously

mentioned. Compatibility needs to be insured and is achieved through well-defined mechanical, electrical and software interfaces.

Appropriate specifications need to be developed that not only ensure interoperability of the systems comprising the Engine as a

Weapon, but also allow for technology refresh and updates as improved technologies mature and are made ready for ship integration.

One such architecture is an Open Architecture (OA). Under an OA arrangement, the interface specifications are defined and owned

by the government. The components, or “boxes” feeding the interface, are procured competitively from industry, and foster technical

refresh and affordability.

CONCLUSION

As the U.S. Navy continues to adapt in order keep the pace with the threat, technological, and fiscal environment, they will be met

with ongoing challenges including reduced dependency upon fossil fuel, meeting increased demand for power, and understanding and

controlling costs (Eccles 2008). The Electric Ships Office (PMS 320), chartered in November 2007 by the Assistant Secretary of the

Navy for Research, Development and Acquisition (ASN RD&A), offers a method to overcome these challenges, by helping the U.S.

Navy enterprise to understand the fleet‟s fuel usage drivers working with ONR to invest early in relevant technology, and reduce

risks for the various Program Executive Office (PEO) acquisition programs through integrated system demonstrations.

Ships with Compact IPS and the myriad of electric and directed energy weapons such as EMRG as envisioned in the current ONR

INP are “game changing” technologies that have the potential to provide much needed, sea-based NSFS and novel, long-range fire

capability ashore. Furthermore, these weapon systems, coupled with the integrated propulsion system architecture, will provide the

US Military with unparalleled flexibility, increased shipboard safety, and a significant increase in volume of firepower that can be

brought to bear in support of our forces afloat and ashore.

ACKNOWLEDGEMENTS

The authors would like to acknowledge and thank Dr. Timothy J. McCoy, director of PMS 320, ESO for his direction and support,

and also the Institute of Marine Engineering Science & Technology (IMarEST) for sponsoring a technical venue, such as this Engine

as a Weapon International Symposium, where the technical rationale and viewpoints contained herein can be presented. The authors

would also like to recognize the U.S. Office of Naval Research, Dr. Rich Carlin (ONR 33), Dr. John Pazik (ONR 331), Mr. Mike

Deitchman (ONR 35), and Dr. Roger McGinnis (ONR 352) for investments in scientific research and technology development and

the innovative concepts delivered by Naval Surface Warfare Centers. Finally, the support from our colleagues at the Naval Sea

Systems Command and Herren Associates, Inc. is gratefully acknowledged.

LIST OF ACRONYMS

Acronym Meaning

A2AD Anti-access / Area-denial

ACAT1 Acquisition Category One

AEW All Electric Warship

AMDR Air and Missile Defense Radar

APS Auxiliary Propulsion System

ASBM Anti-Ship Ballistic Missiles

ASCM Anti-Ship Cruise Missile

ASN RDA Assistant Secretary of the Navy Research Development and

Acquisition

ATG Auxiliary Turbine Generator

BQ Beam Quality

CJCS Chairman of the Joint Chiefs of Staff

CODLAG Combined Diesel-Electric and Gas Turbine

CODLOG Combined Diesel-Electric or Gas Turbine

DE&EW Directed Energy and Electric Weapons

DOD Department of Defense

EMALS Electromagnetic Aircraft Launch System

EMRG Electromagnetic Railgun

EO Electro Optical

ESO Electric Ships Office

FEL Free Electron Lasers

FNC Future Naval Capabilities

HED Hybrid Electric Drive

HEL High Energy Lasers

HM&E Hull, Mechanical & Electrical

INP Innovative Naval Prototype

IPS Integrated Power Systems

LaWS Laser Weapon System

MFAC Medium Frequency Alternating Current

MJ Megajoule

MLD Maritime Laser Demonstration

MSC Military Sealift Command

MTG Main Turbine Generator

MVDC Medium Voltage Direct Current

MVMF Medium Voltage Medium Frequency

MW-class Megawatt-Class

NGIPS Next Generation Integrated Power Systems

NM Nautical Mile

non-DE non-Directed Energy

NPS Naval Postgraduate School

NSFS Naval Surface Fire Support

NSWCDD Naval Surface Warfare Center Dahlgren Division

OA Open Architecture

ONR Office of Naval Research

PEO Program Executive Office

PFN Pulse Forming Network

PGM Power Generation Module

QDR Quadrennial Defense Review

QOS Quality of Service

R&D Research and Development

RAM Rockets Artillery and Mortar

S&T Science and Technology

SECDEF Secretary of Defense

SSL Solid State Laser

SSP Strategic Systems Programs

TACAIR Tactical Air

TDR Technology Development Roadmap

TRL Technology Readiness Level

UAV Unmanned Air Vehicles

USMC United States Marine Corps

UXO Unexploded Ordnance

ZEDS Zonal Electric Distribution System

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