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ANALYSIS OF TRADITIONAL AERIAL SYSTEMS AND FUEL-EFFICIENT UNMANNED AERIAL VEHICLES (UAV) IN SUPPORT OF SPARE PARTS DELIVERY OF SHIPS AT SEA
No full textThis project conducts cost analysis of traditional aerial delivery systems using the MH-60S Seahawk and CMV-22B Osprey, against emerging fuel-efficient hybrid vertical takeoff and landing (HVTOL) unmanned aerial vehicles (UAVs), like Unmanned Aerospace’s GH-4 Gyrocopter. Spare parts are essential for maintaining operational readiness of the Department of Defense (DoD) ships. A lack of spare parts can result in excessive downtime and inability to support the mission. When a part is unavailable, it must be flown in from shore or another vessel, typically using rotary-wing or tiltrotor aircraft like the MH-60S and CMV-22B. These expensive delivery methods can limit aircraft availability for other critical missions. With the emergence of fuel-efficient UAVs, it is important to investigate their potential as a feasible and cost-effective solution to delivering spare parts to ships at sea. This study evaluates the acquisition and operational costs associated with both types of systems, considering multiple factors. It finds that UAVs, particularly the Kargo UAV, provide a cost-saving advantage over traditional aerial logistics platforms like the MH-60S Seahawk and CMV-22B Osprey. Therefore, it recommends that the Department of the Navy (DON) conduct pilot programs to further assess the performance, reliability, and interoperability of UAVs in logistical roles.Distribution Statement A. Approved for public release: Distribution is unlimited.Outstanding ThesisCivilian, Department of the NavyCivilian, Department of the Nav
BALLISTICALLY IMPACTED SELF-SEALING FUEL HOSES IN EXTREME COLD TEMPERATURES
No full textThe current design of the U.S. Army UH-60 helicopter does not provide protection from ballistic threats to the fuel lines. A requirement to prevent fuel loss from ballistic impacts up to 0.50 caliber has been identified with the ability of fuel lines to instantaneously self-seal within a temperature range of -40°C to 121°C while pressurized to 275.8 kPa. Previous research at the Naval Postgraduate School enabled successful self-sealing performance at both ambient and high temperatures (121°C). Self-sealing performance at -40°C was unsuccessful due to brittle failure caused by impacts below the glass phase transition temperature. Material studies were performed to investigate self-sealing hose systems with low glass phase transition temperatures. As many polymers with low glass phase transition temperature have limited strength, alternative methods to reinforce the polymers using fiber meshes and compression adhesives were incorporated to enable self-sealing at -40°C while pressurized to 275.8 kPa.Distribution Statement A. Approved for public release: Distribution is unlimited.Ensign, United States Nav
AN INVESTIGATION INTO THE EFFECTS OF NONLINEAR FORCES ON MARINE SEDIMENT ACOUSTICS
Get PDFThis research continued the development of a grain-based simulation approach to sediment acoustic propagation by testing whether previous results on anomalous attenuation scaling were sensitive to the more realistic Hertzian force law between grains. Naval acoustic sonar systems rely significantly on how sound bounces off the ocean floor and sound reflection off a soft, sandy ocean floor is notoriously poorly understood. A complete understanding of the frequency dependence of phase speed and attenuation coefficient would close this knowledge gap. Previously, our work has shown that the disordered packing structure of granular materials has a significant effect on the frequency dependence of phase speed and attenuation of acoustic waves, which has not historically been considered. Here we demonstrate (1) that the previously observed frequency dependence of attenuation is not significantly affected by Hertzian contact forces between particles and (2) that the Hertzian force law can be approximated locally at each grain as a linear force law. Our results here show that the Hertzian contact force law is not a dominant factor in novel scaling trends observed previously. By continuing this research and refining our model, a better conceptual understanding of how bottom bounce propagation functions will continue to push our understanding of marine acoustics.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant, United States Nav
CHARACTERIZING DEFECTS IN SAND CAST MAGNESIUM ALLOY COMPONENTS
No full textMagnesium is the lightest metal used in aircraft. Its excellent damping capacity, high strength-to-weight ratio, and light weight make it useful for non-load bearing components in vibrating environments like transmission gearboxes. The U.S. Army (USA) currently uses sand cast magnesium alloys in their helicopter transmission gearboxes. As the cost of fuel and the need for implementing lightweight technology increases in the Department of Defense (DoD), magnesium alloys remain a promising material. Although sand casting is desirable for low volume production of complex parts due to lower tooling and material costs, the process is imperfect, and magnesium alloys are susceptible to shrinkage, porosity, inclusions, and segregation. This research examined two different alloys produced in magnesium foundries (ZE41 and Elektron 21) and identified the type and extent of defects present. The Helios 5 Scanning Electron Microscope (SEM) and X5000 Industrial CT Scanning System were used to view the surface and inside of different alloys and characterize defects so that they can be better modeled in the future. Significant microsegregation was found in all samples. Defective ZE41 regions had a larger grain structure and lower grain boundary area fraction than defect-free regions. A defect-free region of Elektron 21 was also characterized. Inclusions were observed in ZE41, and all Elektron 21 samples exhibited significant shrinkage porosity.Distribution Statement A. Approved for public release: Distribution is unlimited.Outstanding ThesisEnsign, United States NavyOffice of the Undersecretary of Defens
EXPANSION AND STABILITY ANALYSIS OF A DUAL ATOMIC BEAM GYROSCOPE
No full textModern Naval vessels utilize Inertial Navigation System (INS) as a navigation tool. Roll, pitch, and yaw data, commonly referred to as attitude data, require onboard gyroscopes and accelerometers. Many weapon systems such as the Navy’s Standard Missile (SM) family require inertial navigation data for operation. Current inertial navigation data for linear acceleration is provided by accelerometers, and rotational acceleration data by optical gyroscopes. However, there are inherent sensitivity limitations to these systems that are fundamentally related to the properties of measuring acceleration changes with a massless photon. If an INS system is being used as a primary method of navigation, it does not have the ability to be checked against another source to reset the drift. This happens when operating in a GPS-denied environment or other situations. Atom interferometry shows promise to provide both linear and rotational data simultaneously with an increase in sensitivity by orders of magnitude relative to current systems, all while being less affected by drift due to the intrinsic characteristics of the atoms which, by definition, do not change over time. Improving the attitude data that INS have access to will significantly enhance both the duration of time they are accurate, and the degree to which they maintain accuracy. This research will continue to investigate the physics of atom interferometry, and the application of this technology as an accelerometer and gyroscope.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant, United States Nav
FORGING THE LOGISTICS COALITION: ENHANCING U.S. MARINE CORPS DISASTER RESPONSE IN THE INDO-PACIFIC
No full textThe U.S. Marine Corps must enhance its logistical capabilities to support both warfighting and humanitarian assistance/disaster relief (HA/DR) operations in the Indo-Pacific's distributed maritime environment. This research provides a paradigm for addressing HA/DR response in the strategically relevant and natural disaster-prone region. It introduces a "logistics coalition" as a strategic initiative to improve response effectiveness by leveraging prepositioning concepts.This research centers around a network model focused on the distribution of five equipment types from eight supply nodes (Okinawa military base, Yokota air base, Guam military base, Philippines, Singapore, Diego Garcia, Darwin, and South Korea) to six demand nodes (Philippines, Indonesia, India, Taiwan, Thailand, and Japan). It develops six mathematical models, each aligned to a different demand node, to identify the most efficient prepositioning network for HA/DR response in the Indo-Pacific. The models are computed in Microsoft Excel using linear programming techniques to optimize the allocation of resources across the network. The results highlight key prepositioning sites and provide recommendations for resource allocation across Department of Defense (DoD) sites in the region. The research proposes a logistics coalition and offers decision-makers with a model framework to improve HA/DR readiness, ensuring timely and effective disaster response in the Indo-Pacific.Distribution Statement A. Approved for public release: Distribution is unlimited.Captain, United States Marine Corp
FERTILIZING FUTURE LEADERS: AN EXAMINATION OF THE MIAMI POLICE DEPARTMENT’S EFFORTS TO DEVELOP THE CAREERS OF ITS POLICE OFFICERS
No full textLaw enforcement agencies across the United States face ongoing retention challenges, and the Miami Police Department (MPD) is no exception. This study examines MPD’s career development and mentorship programs to assess their impact on officer retention, job satisfaction, and organizational stability. Using a case study methodology, the research incorporates survey data, structured interviews, and an analysis of MPD’s career advancement policies. Findings indicate that while mentorship and career development opportunities exist, concerns about fairness in promotions, limited access to leadership training, and a lack of clearly defined career tracks contribute to officer dissatisfaction. Officers who engaged in structured career development programs reported a stronger commitment to MPD, whereas those perceiving career stagnation were more likely to consider leaving. The study recommends implementing a formal mentorship program, expanding access to leadership training, and establishing defined career tracks to provide officers with clear pathways for advancement. By addressing these challenges, MPD can improve officer morale, strengthen workforce stability, and build a more committed police force.Distribution Statement A. Approved for public release: Distribution is unlimited.Civilian, Miami Police Departmen
DESIGN AND ANALYSIS OF A MODULAR ADDITIVELY MANUFACTURED AXISYMMETRIC MACH 5+ HYPERSONIC WIND TUNNEL
Get PDFWith interest surrounding the development of hypersonic weapons, hypersonic wind tunnels are necessary to validate computer simulations of different geometries and technologies. Additive manufacturing processes associated with the construction and testing of hypersonic wind tunnels will aid in expediting the process and lowering the cost of acquiring components of a wind tunnel. An additively manufactured hypersonic wind tunnel would eliminate the difficulty associated with acquiring and manufacturing components to construct a hypersonic wind tunnel. Additionally, adding flexibility to the types of testing that can be conducted on one tunnel would allow for hypersonic research to be more accessible and easier to conduct. This thesis will focus on the design of a modular, axisymmetric wind tunnel capable of reaching Mach 5+. The paper details the design process, starting from optimizing the fluid domain to designing potential concepts for construction, followed by structural analysis of the components at the operating conditions.Distribution Statement A. Approved for public release: Distribution is unlimited.Ensign, United States Nav
Evaluating TTPs for Use of Acoustic Forecasts in USW
Get PDFNPS NRP Executive SummaryThis research assesses whether, how, and under what circumstances ocean and acoustic forecasts used with tactics, techniques, and procedures (TTPs) and optimization algorithms, improve undersea warfare (USW) search mission outcomes, and how the choice of environmental inputs, and the way they are used in decision making, can better exploit forecasts and improve mission outcomes. Using an experimental system that combines on the experimental capability combining historic ocean models with Navy acoustic models and USW mission models, we studied the impact of ocean variability in the Kuroshio extension region in the North Pacific and the region of the South Cyprus eddy in the Eastern Mediterranean. We found that geographic and temporal variability, even on the scale of one to two days are highly relevant, which supports the importance of daily acoustic runs using updated ocean models. Both TTPs and optimization algorithms were found to use highly simplified assumptions regarding the acoustic environment. The results of this interdisciplinary study suggest that environmentally informed TTPs and formulations of optimization models for search planning can improve mission outcomes compared to environmentally naïve formulations. Such improvements are being pursued in ongoing research.Approved for public release. Distribution is unlimited.This research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)N2/N6 - Information Warfar
