Naval Combatants Research Articles

Large Uncrewed Surface Vessel: An opportunity for Energy Transition?

Driven by the IMO target to make the maritime industry net-zero in its carbon emissions by 2050, the maritime industry now has the question of how to create both technically feasible and economically viable solutions. While many are looking at how this can be achieved for currently crewed vessels, even those service vessels such as naval combatants, there is also a real benefit that could be had by combining autonomy with the challenge of meeting the energy transition. Without people onboard there are options to completely change assumptions on layout, deck height and operations that could provide greater available space and counter energy density challenges. Additionally the removal of human life could open the line for other fuels such as ammonia with significant toxicity concerns. This paper investigates the benefits and difficulties that a Large Unmanned Surface Vessel (LUSV) utilising alternative fuel can bring, building on the recent BMT LUSV vision.

Capability driven vulnerability analysis of a naval combatant

This paper presents a fine-tuned approach to vulnerability assessment, focusing on protecting capabilities instead of individual systems and their components. The foundation of this method is a system model which uses functional chains to identify the contribution of individual systems towards to fulfilment of the ships capabilities. The key advantage of using functional chains is that by showing that individual functions can still be fulfilled, it is demonstrated that the vital capability containing those functions remains available. This paper first explains the theory behind the methodology and then demonstrates its working principles using a generalized case study for a single capability.

Experimental and CFD Resistance Validation of Naval Combatant DTMB 5415-51 Model

The hull model of the surface combatant DTMB 5415 has been selected as a recommended benchmark naval ship for computational fluid dynamics (CFD) validation for resistance analysis. CFD is used to present a method for predicting surface combatant ship resistance. The resistance calculations of a 3 m DTMB 5415 hull model was compared using experimental and CFD techniques. The bare hull shape experiments were set up and carried out at the towing tank facilities at the Military Technical College's Hydrodynamic Laboratory in Egypt. A benchmark test will ensure that the equipment, procedures, and estimates of uncertainty are adequate. For the purpose of model validation, CFD calculations for a DTMB 5415-51 model are performed using three different mesh sizes for Froude numbers ranging from 0.10 to 0.40. For the same Froude numbers and free model conditions, results from towing tank experiments on the model's resistance, sinkage, and trim are presented. The numerical simulations are quantitatively consistent. The numerical results are compared in terms of wave field and resistance coefficients to determine the accuracy of the solution parameters. As evidenced by the resistance curves, the experimental investigation appears to provide very good agreement, indicating that the CFD model is capable of simulating the steady flow around a ship hull with acceptable accuracy and can thus be used as a supplement to laboratory model tests for ship design and ship hydrodynamic research.

Sensitivity Analysis of Ship Manoeuvring Mathematical Models

Sensitivity analysis is applied to ship manoeuvring mathematical models as a means of dealing with model uncertainties, and often leads to model simplifications. A rather standard 3DOF manoeuvring model was tuned with the available results of full-scale trials of a naval combatant and was further used as the reference model for sensitivity analysis. The present research was based on multiple perturbed simulations of the turning, zigzag and spiral manoeuvres. A salient feature of the present study is that the perturbations were applied to the total hydrodynamic forces and moments as well as separately to their characteristic parts, i.e., to the linear and nonlinear single-variable and coupled components. Another special feature is that the deviations of the perturbated responses were estimated not only considering the standard manoeuvring performance indices, but also through application of the Euclidean metric directly to the time histories and to the spiral curve. The performed analysis permitted the sensitivity of the model to be traced to various parameters and groups thereof. It was established that the highest sensitivity of the model was to linear and some nonlinear multivariable parameters, and the Euclidean metric permitted a more detailed analysis than that based only on standard discrete manoeuvring indices. The obtained results are expected to be useful in the application of system identification methods to typical inherently stable fast surface-displacement ships.

DESIGN FOR AN ALL-ELECTRIC DESIGN FOR SUPPORT IN INITIAL DESIGN USING THE NETWORK BLOCK APPROACH: A SUBMARINE EXAMPLE

The layout of the Distributed Ship Service Systems (DS3) can be a major constraint both on the location of hull berth unit and of transverse bulkheads, with implications for conducting maintenance and so contribute to submarine Sustainability. This paper proposes a new early-stage ship design (ESSD) approach that would aid the designer to consider DS3 features physically and logically much earlier in the design process. The approach is termed the Network Block Approach and combines the advantages of the UCL 3D physically based ship synthesis Design Building Block (DBB) approach and the network-based approach for distributed ship service systems (DS3) synthesis already proposed for naval combatants. The proposed Network Block Approach enables modelling of individual spaces to locate and zone various DS3 components and take account of hull unit boundaries and major bulkheads. The paper discusses the importance of DS3 routing to warship Sustainability through the complexity of a submarine design example and shows how the proposed approach enables this to be explored in ESSD.

A multilayer network approach to vulnerability assessment for early-stage naval ship design programs

Vulnerability is a crucial facet of a naval ship's operational capability in a hostile environment. Naval combatants are among the most complex and densely packed distributed systems created today. These shipboard distributed systems are defined by their layout and componentry. Vulnerability assessments of these systems are therefore derived from failures of the integrated componentry layout due to hostile weapon impacts. In late-stage design programs, these vulnerability assessments are accomplished via detailed modeling and computationally expensive simulation. During early-stage design, this level of detailed modeling is unavailable, but integrated system failure analysis remains essential for thorough vulnerability assessment. The authors resolve this issue by utilizing an adaptable network-based approach to reduce the design fidelity needed for modeling and simulation. The approach allows for the development of a novel vulnerability assessment method for early-stage design. The approach is demonstrated through a representative naval case study.

Significance of wave data source selection for vessel response prediction and fatigue damage estimation

The availability of detailed environmental hindcast data opens the door for virtual structural health monitoring; however, the impact of hindcast wave data selection on the results of such an approach have not been explored. While studies on the differences between wave models have been conducted in the past, extensions of these comparisons to resultant vessel response predictions and fatigue damage estimates are limited. At three separate geographical locations, this work compared hindcast wave data from NOAA's WAVEWATCH III (NWW3) Multigrid Production Hindcast, the EU's CMEMS Global Ocean Waves Analysis and Forecasting Product, and National Data Buoy Center buoys. In addition to comparisons of wave parameters at each location, the resultant heave, pitch, and vertical bending moment responses and fatigue damage of a destroyer-sized naval combatant, the DTMB 5415, were compared. The novelty of this work lies in its large scope, which calculated responses every 3 h for all of 2017 in 32 speed and heading combinations for each location and wave data source. The results show that differences between wave data sources propagated to the vessel response predictions. These differences were then amplified in the calculation of fatigue damage causing significant discrepancies between data sources after just one year.

Wavelet-Based Time-Domain Solutions for Common-Mode Currents on Open-Form Conductors Modeled With Band-Limited Scattering Parameters

One of the technical challenges of future naval surface combatants in utilizing medium-voltage dc distribution systems is common-mode coupling and galvanic isolation for managing faults and personal safety. The behavioral modeling reported in this paper is computationally efficient to be used in modeling distributed common-mode currents and potentials throughout the open-form conductor, which in this case is the ship structure. Physics-based modeling is used to form a multiport S-parameter behavioral model of the ship structure that complements the S-parameter models of parasitic paths to grounded equipment enclosures and cables sheaths. A time-domain common-mode conduction example is presented to illustrate the workflow that converts physics-based models of elementary hull elements into a complete S-parameter behavioral model of an arbitrary hull structure with power cables running along it. Because of the measurement and the simulation bandwidth limitation, the frequency domain model based on S-Parameters is band-limited. A novel approach for reconstructing the system impulse response in the time domain from its band-limited S-parameter model is introduced using continuous wavelet transform utilizing fast Fourier transform.

The Sophistication of Early Stage Design for Complex Vessels

Prior to the introduction of computers into Early Stage Ship Design of complex vessels, such as naval ships, the approach to synthesising a new design had been via weight equations. When it was realised that modern naval vessels (and some sophisticated service vessels) were essentially space driven initial (numerical) sizing needed to balance weight and space, together with simple checks on resistance & powering, plus sufficient intact stability (i.e. simple metacentric height assurance). All this was quickly computerised and subsequently put on a spread-sheet to iteratively achieve weight and space balance, while meeting those simple stability and R&P checks. Thus suddenly it became possible to produce very many variants, for both trade-off of certain requirements (against initial acquisition cost) as well (apparently) optimal solutions. However as this paper argues this speeding up of a very crude synthesis approach, before rapidly proceeding into feasibility investigations of the “selected design”, has not led to a quicker overall design process, nor have new ship designs been brought earlier into service, in timeframes remotely comparable to most merchant ships. It is the argument of this paper that such a speeding up of an essentially simplified approach to design synthesis is not sensible. Firstly, there is the need to conduct a more sophisticated approach in order to proceed in a less risky manner into the main design process for such complex vessels. Secondly, further advances in computer techniques, particularly those that CAD has adopted from computer graphics advances, now enable ship concept designers to synthesise more comprehensively and thereby address from the start many more of the likely design drivers. The paper addresses the argument for a more sophisticated approach to ESSD by first expanding on the above outline, before considering important design related issues that are considered to have arisen from major R.N. warship programmes over the last half century. This has been done by highlighting those UK naval vessel designs with which the author has had a notable involvement. The next section re-iterates an assertion that the concept phase (for complex vessels) is unlike the rest of ship design with a distinctly different primary purpose. This enables the structure of a properly organised concept phase to be outlined. Following this the issue of the extent of novelty in the design of a new design option is spelt out in more detail for the seven categories already identified. The next section consists of outlining the architecturally driven approach to ship synthesis with two sets of design examples, produced by the author’s team at UCL. All this then enables a generalised concept design process for complex vessels to be outlined, before more unconventional vessels than the naval combatant are briefly considered. The concluding main section addresses how a range of new techniques might further alter the way in which ESSD is addressed, in order to provide an even better output from concept to accomplish the downstream design and build process. The paper ends with a summary of the main conclusions.

Iraq, Afghanistan, and rethinking the post‐heroic turn: Military decorations as indicators of change in warfare

AbstractThis article compares the awarding patterns of the two senior Anglophone military decorations, the British/Commonwealth Victoria Cross and the American Medal of Honor, to challenge arguments that a shift to ‘post‐heroic’ warfare has been in progress in Western societies since 1990. Despite the two decorations being independent of each other, each born of a particular military, political, and social context in their respective parent societies, the article reveals strong consistencies across the two. These include common understandings of military heroism centred on infantry‐ rather than machine‐intensive combat, and a shared neglect of armoured, aerial, and naval combatants. Crucially, the medal data suggests that, despite academic suggestions to the contrary, there was no discernible shift towards ‘post‐heroism’ in the post‐Cold War era. Such a shift, however, is observable between 1916 and 1920, suggesting that the ‘new Western way of war’ began far earlier than is often suggested.

China’s Troubled Waters: Maritime Disputes in Theoretical Perspective, by Steve Chan. Cambridge: Cambridge University Press, 2016. 250 pp. US$99.99 (cloth).

<i>China’s Troubled Waters: Maritime Disputes in Theoretical Perspective</i>, by Steve Chan. Cambridge: Cambridge University Press, 2016. 250 pp. US$99.99 (cloth).

Hybrid Electric Drive for Naval Combatants

This paper presents an overview of the development and present state of the art of hybrid propulsion drive systems as applied to high-performance naval combatants. Motivations for implementing hybrid electric drive architectures are reviewed including potential benefits in term of fuel savings/reduced emissions and additional power generation capacity. Both back-fit into existing propulsion and power generation architectures as well as forward-fit are discussed. Issues associated with coupling the mechanical drive train and electric power generation system together are reviewed.

Fighting Ships that Require Knowledge and Experience: Industrial Mobilization in American Naval Shipbuilding, 1940–1945

Wartime naval builders in the United States constructed the world's largest fleet that defeated the Japanese Imperial Navy, aided the Allied victory during the Battle of the Atlantic, and projected American naval power into all corners of the globe. Many naval combatants were built by highly experienced shipbuilders who possessed advanced design skills and production capabilities that had been years in the making. The present study examines the structures and dynamics of American naval shipbuilding and compares them to their foreign counterparts; it argues that extant capabilities were vital to the success of the U.S. war economy.

Identifying drivers of general arrangements through the use of network measures of centrality and hierarchy

Developing three-dimensional space and system arrangements is a challenging and time-consuming task because ship layouts include hundreds or thousands of elements with multiple interconnections and dependencies governed by functional characteristics. Existing automated arrangements tools aimed at early-stage design are capable of generating feasible layouts, but remain a bit of a “black box,” lacking methods to elucidate the mechanisms that drive or limit the quality of those layouts. By knowing which items drive or constrain an arrangement, designers can more judiciously decide when and where to position objects. Methods that provide this information are particularly valuable for novel ship types, designs containing emerging technologies, or densely outfitted vessels such as naval combatants and submersibles. The use of networks to represent the interconnections allows designers to focus on the underlying relationships input into the system rather than just the resultant layouts. The authors use the complex network measures of centrality and hierarchy to identify layout drivers based solely on the relationships among the spaces to be arranged. Moreover, the methods are shown to permit identification of drivers without ever creating geometric arrangements.

Advances in ship survivability against underwater explosions

Mines, torpedoes and improvised explosive devices (IED) pose a serious threat to the survivability of naval combatants. Inasmuch, a major goal in the design of modern combatant ships has been to eliminate or at least reduce the devastating damage caused by underwater explosion events. Even though there has been extensive research performed on the various underwater explosion phenomena and their associated effects, effective shock testing and shock proofing strategies for naval ship systems have proven to be illusive. Through the use of modeling and simulation (M&S), live fire test and evaluation (LFT&E) and laboratory testing, general guidelines for the shock hardening of shipboard equipment and systems have been developed. In this paper, current aspect of ship survivability has been addressed and future direction is discussed.

A branch and bound algorithm for sector allocation of a naval task group

A naval task group (TG) is a collection of naval combatants and auxiliaries that are grouped together for the accomplishment of one or more missions. Ships forming a TG are located in predefined sectors. We define determination of ship sector locations to provide a robust air defense formation as the sector allocation problem (SAP). A robust formation is one that is very effective against a variety of attack scenarios but not necessarily the most effective against any scenario. We propose a 0-1 integer linear programming formulation for SAP. The model takes the size and the direction of threat into account as well as the defensive weapons of the naval TG. We develop tight lower and upper bounds by incorporating some valid inequalities and use a branch and bound algorithm to exactly solve SAP. We report computational results that demonstrate the effectiveness of the proposed solution approach. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011

A demonstration of an advanced library based approach to the initial design exploration of different hullform configurations

The importance of requirement elucidation, in shaping both the customers’ needs and initial solutions during the concept stage of the ship design process, has previously been emphasised in the choice of initial design methods. It is well known that alternative hullform styles can bring distinct performance benefits in certain design investigations. However, current design methods or tools suitable for exploring alternate hullform styles during requirement elucidation do not readily facilitate this. This paper describes a library based ship concept design tool and its ability to include exploration of hullform options in the initial exploratory stage of the ship design process. The library based approach utilises sub-structuring to describe the design in terms of four functional subsets to increase the efficiency of the search process. The example presented looks at monohull, catamaran and trimaran hullform options for a fast naval combatant. The paper concludes with the advantages seen in adopting the tool in concert with a configuration-oriented approach to ship design, namely, the UCL Design Building Block approach.

Forecasting System-Level Impacts of Technology Infusion in Ship Design

This study examines a methodology that can aid the decision maker in projecting the performance of future vessel concepts and in allocating the resources for technological research and development in an optimum way. The method is generic, and can be applied to any system that can be modeled mathematically, such as a naval surface combatant or submarine. The method combines system-level design parameters with technology impact assessment. The impact of technology is assessed through the use of technology k-factors through a design of experiments and response surface method that is coupled with a computational ship synthesis model to modify the technical characteristics or the cost parameters of the design. These modifications result in changes to the technical metrics used to simulate the hypothetical improvement or degradation associated with the new technology. This methodology is demonstrated through a technological impact assessment of the operational characteristics of a conventional submarine design.

Ranking maritime platform upgrade options

Naval combatants remain on active service for decades. This necessitates their functional enhancement in order to keep pace with the latest advances in technological developments and changes in future military threats. This paper introduces the activity of technology insertion by providing an overview of the past, current, and future upgrades of the DDG-51 class destroyer's combat system. Within technology insertion, there is the requirement for potential upgrade options to be analysed from a functional perspective. The upgrade matrix, based on the quality function deployment method, is proposed as a tool for such a task. This matrix functionally decomposes a platform's combat roles, principal systems and sensor-to-shooter loop. These functions are rated against capability gaps and user importance weightings. A set of options can then be assessed for their contribution to fulfilling the user's future needs. The result is the identification of the most appropriate upgrade options. The use of the upgrade matrix is demonstrated through an illustrative example which is conceptually based on the anti-air warfare elements of the Type 45 destroyer's combat system.

Maintaining Naval Combatants in ABS Classification In‐Service

AbstractThe American Bureau of Shipping and the Naval Sea Systems Command have been working together over the last several years in a measured initiative to develop and apply classification Rules for naval vessels, and currently both littoral combat ship (LCS) programs and the DDG‐1000 program require that the vessels be built and delivered in class to the Naval Vessel Rules. In addition, the JHSV platform will be delivered in class with ABS. It has been decided that the LCS platforms will be retained in class as a part of their maintenance philosophy. If this is successful, then DD‐1000 will also be retained in class. The JHSV, as are all Military Sealift Command ships, will be retained in class in‐service. This paper reviews the background supporting this initiative, describes the concept of retention in class, outlines the approach adopted, and reviews the current status of application.