7 4 ■ SUMMER 2002 NAVAL ENGINEERS JOURNAL

ASNE DAY 2002LHD 8: A Step Toward the All Electric Warship Thomas Dalton, Abe Boughner, C. David Mako and Cdr. Norbert Doerry, USN

ABSTRACTThe recently commissioned Iwo Jima (LHD 7) is the last ship with conventional steampropulsion that the U.S. Navy plans to build. The LHD 8 is the next ship of the classand will be built as a modified repeat design of the LHD 7. The key modifications aresteam propulsion being replaced with a hybrid propulsion system of main gas turbineengines augmented with auxiliary propulsion motors and electric powered auxiliariesreplacing those powered by steam. The LHD 8 will also be the first USN surface shipto implement a 4160 VAC Zonal Electrical Distribution System (AC ZEDS) as well asthe integrated power system concept for electrical power generation, distribution andpropulsion. These modifications embody the intent of the all electric warship conceptfor the future U.S. Navy. This paper presents the constraints and issues involved in thedesign process by addressing major design impacts and significant design concerns.This text explores the design options within the available trade space and illustratesspecifically how the Fleet/mission requirements, LHD 7 hull design and propulsionshafting constraints, schedule and funding drove the propulsion system design.

COMMENTS BY TIMOTHY J. MCCOYThe authors are to be congratulated on a very comprehensive paper. They’vemanaged to cover in a relatively short document the process by which thepresent design for the LHD 8, hybrid electric/mechanical drives system cameinto being.

The most intriguing aspect of the paper is how the Auxiliary PropulsionSystem (APS) is categorized as non-mission critical vice mission critical. Whilethis is unusual for propulsion equipment, it is an important distinction whichallows the use of true COTS technology vice Mil-Spec compliant componentswhich would undoubtedly require a costly and time consuming developmenteffort. Making the APS “non-mission critical” eliminates the grade A shockrequirement, as the authors note, which can be a significant cost and designcomplexity driver for power electronics and can increase the cost of electricmachines by 10-20%. This designation also removes the APS fromOperational Availability (Ao) calculations and relieves the designers from ahost of other military requirements.

Since the ship would be expected to utilize the electric drive mode of operationfor a significant amount of its lifetime, optimizing that operational modewould seem to be a natural desire. Some readers might be prone to ask whynot eliminate the CPP system in favor of a simpler fixed-pitch propeller orwhy not use a low speed motor mounted on the propulsion shaft so the reduc-tion gear could be “clutched out?” However, the ultimate design the authorsdescribe is ingenious in that the mechanical drive operational mode canaccomplish all the ship’s missions, albeit some of them very inefficiently,allowing the APS to be designated as “non-mission critical.”

[ T E C H N I C A L P A P E R C O M M E N T S ]

74 LHD 8: AStep Towardthe All

Electric Warship

Thomas Dalton, Abe

Boughner, C. David Mako

and Cdr. Norbert Doerry, USN

75 CollaborativeEngineeringAcross

OrganizationalBoundariesArt Boyars, NSWC, W. Aldo

Kusmik, NUWC, and Mike

Yukish, ARL/PSU

77 DesigningNavy HullForms

for Fuel Economy

Gabor Karafiath, Donald

McCallum, and Dane

Hendrix

81Developmentof Shipbuilder and Supplier

Relationships

Dr. John C. Daidola, P.E. and

John H. Higginbotham

The LHD 8 designers have, in effect, devel-oped a system that is analogous to the par-allel-hybrid-electric automobiles now beingoffered by Honda and Toyota. Becausesome of the electric drive components(notable the VSD’s) do not yet have the reli-ability that consumers have come to expectfrom their automobiles, they are designedto be, in effect, “non-mission critical.”Unlike the many series-hybrid prototypesdeveloped at some university labs, the elec-tric and mechanical prime movers are con-nected via mechanical vice electrical meansand either prime mover can drive the car.Consequently, a failure of one of these com-ponents will not leave the car’s ownerstranded along side of the road. In a serieshybrid, a failure of the electric propulsionmotor or its associated VSD leaves the carowner looking for a tow-truck. Auto mak-ers have been providing such back-ups formany years in a variety of ways. A valuablelesson for all warship designers as there’sno “tow truck” in the Indian Ocean.

The design presented by the authors is truly agiant step towards the all-electric Navy of thefuture and will result in a more reliable andefficient LHD than its predecessors. It is alsorefreshing to see sound engineering analysisbeing used to develop a ship design vs. handwaving and “viewgraph engineering” that isall too common today. Well done.

Collaborative Engineering AcrossOrganizational BoundariesArt Boyars, NSWC, W. Aldo Kusmik, NUWC,

and Mike Yukish, ARL/PSU

ABSTRACTThe design of next-generation undersea weaponsystems involves optimizing over many compet-ing disciplines and objectives, and requires abroad range of technical expertise that is notresident within a single organization. Thus, theoptimization and development of these systems

requires the involvement of multiple govern-ment, academic, and commercial organizations.This paper provides lessons-learned as a resultof a four-year effort in the Simulation BasedDesign (SBD) of undersea weapons. During thistime, Naval Undersea Warfare Center (NUWC),Naval Surface Warfare Center (NSWC), andApplied Research Laboratory at thePennsylvania State University (ARL/PSU) haveexplored different methods of collaboratingacross the organizations, and have identifiedmany sources of friction hindering the collabo-ration. Some are well known, such as fileincompatibility between CAD systems. Othersare less studied but more fundamental, such ascultural differences between organizations. Inorder to facilitate collaboration and ultimatelysupport the change in paradigm of acquisition,each must be addressed and resolved.

COMMENTS BY JAMES GRIFFINOF NUWC NEWPORT DIVISIONIn the subject article the authors provide anoverview of the sources of friction hinderingcross organizational collaboration during thedesign development process. The articlebriefly reviews the technical barriers to col-laboration before focusing on the psychologi-cal barriers. No attempt is made to define orcharacterize the specific requirements forimplementation of a collaborative designenvironment, but rather the focus is on theorganizational impediments which includeprotection of proprietary information, a lackof standardized design and information man-agement tools, and the use of unique, organicmodels in a multi-organizational team.

The authors provide valid insights intothese issues, but do not offer proposedsolutions to address them. Other issuesthat require further exploration are theprocess for ensuring that the products builtin the new collaborative design environ-ment are actually improved, or ideallyoptimized, versus the standard designprocess and the requirement for a persis-

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