Search

This work presents a novel approach to modeling an underwater optical wireless communications (UOWC) channel based on a deterministic analysis specifically for non-line-of-sight (NLOS) configurations. The model considers the presence of a wavy ocean surface, providing a more accurate representation of realistic conditions. By expanding the possibilities for communication in complex underwater environments, our model offers a comprehensive analysis of the ocean waves' impact. A significant achievement of this study is the capacity of the model to accurately compute the variable size of the width of the beam (footprint) on the receiver plane reflected by the sea surface and the time intervals during which the receiver remains illuminated. Additionally, the model determines the precise position of the reflected beam on the receiver plane and accurately identifies the time intervals during which communication is feasible, offering invaluable insight into the system performance under oceanic wave variability. The results confirmed that oceanic wave variability induces severe misalignment in optical links, creating intermittent opportunities for effective communication. The optical–geometric analysis contributed significantly to understanding the novel impact of ocean waves on NLOS-UOWC systems. These findings enhance the preliminary considerations in NLOS link design, particularly in scenarios with autonomous underwater vehicles in constant motion, aiding in the reduction of pointing errors. [ABSTRACT FROM AUTHOR]

A rock cairn, with two matchbooks buried beneath, was found on the summit of the highest hill on Thomas Island, Bunger Hills, East Antarctica. The matchbooks are most likely from United States World War II-era ration packs, which were distributed to various military and civilian expeditions from the mid-1940s into the 1950s. Bunger Hills was first visited by United States Navy 'Operation Highjump' in February 1947, when a seaplane most likely landed on a marine inlet, rather than a lake as reported previously. Thomas Island was first visited by United States Navy 'Operation Windmill' in January 1948, when a survey point was established, and it is probably this location that is marked by the rock cairn. The matchbooks were replaced beneath the cairn and the rocks replaced. Just over 76 years had elapsed between burial of the matchbooks, construction of the cairn and their rediscovery. [ABSTRACT FROM AUTHOR]

Seaplane operations connect remote areas, promote tourism, and provide unique transportation solutions. After many years of preparations, commercial seaplane operations on a network of 100 water airports and 200 waterways in Greece are about to commence. The network can serve the needs of 1.6 million permanent residents of the Greek islands, the inhabitants of the mainland, and over 35 million annual tourists. This paper aims to conduct a PESTLE (Political, Economic, Social, Technological, Legal, and Environmental) analysis to identify the factors that have delayed operations and those that will affect the success of future operations. As such, 26 factors are examined. It was found that the Greek debt crisis and the COVID-19 pandemic were impediments to operations. The potential of using electric seaplanes is discussed. Recent developments in using drone inspection capabilities for aviation safety are examined. Management strategies for the Etesian winds and other environmental issues are presented. Overall, seaplane operations have enormous potential, while the Greek economic recovery provides favorable conditions for completing the project. The critical issue determining success is executing a multi-faceted business model to ensure seaplane operations' financial viability. The network can act in synergy with other modes of transportation to help achieve social cohesion, improve tourism services, and foster economic development. [ABSTRACT FROM AUTHOR]

To reduce the aerodynamic performance degradation caused by the sculling phenomenon on the flap of amphibious seaplanes, this study proposes a grid-slat fusion design method that integrates grid channels into the slats to create multiple lift surfaces. This new configuration enhances not only the lift capacity of the slats but also the lift characteristics of the main wing, leveraging ejector effects from the grid channels. A grid-slat fusion configuration parametrization method is developed based on the "new conic curve" concept, and an optimization approach is implemented using the NSGA-II algorithm. Computational fluid dynamics (CFD) verification of the 30P30N airfoil demonstrates that the grid-slat fusion design enhances the lift-to-drag ratio of the optimized 2D configuration by up to 8.5% at a specific condition, thereby significantly improving its aerodynamic performance at high angles of attack and meeting the requirements for take-off and landing. The three-dimensional configuration demonstrates a stall angle of attack delay of 2° and a maximum lift coefficient increase of 6%. Furthermore, the grid-slat composite configuration allows a better lift-to-drag ratio, and its aerodynamic characteristics improve with increasing wave height. During the wave runup phase, aerodynamic performance is further enhanced, with different wave positions significantly influencing the aerodynamic performance. [ABSTRACT FROM AUTHOR]

The article focuses on the development of the Royal Canadian Air Force's (RCAF) Victoria Beach station from 1921 to 1926. Topics include the establishment of the Victoria Beach air station as a hub for civil aviation, the use of flying boats for forest fire reconnaissance, and the operational challenges and advancements in aerial survey methods for mapping northern Canada.

The article focuses on the restoration and replica of the Canadian Vickers Vedette flying boat at the Royal Aviation Museum of Western Canada. Topics include the history and significance of the Vedette in Canadian aviation, the challenges and efforts involved in creating the replica, and the role of volunteers and museums in preserving aviation heritage.

The distribution of holographic unsteady water load offers important information for evaluating the hydrodynamic performance of seaplanes. However, traditional tank test is limited by the number of sensors that can be deployed on the bottom of hull, thus only providing sparse data for estimating load distribution and leading to inaccurate evaluation of seaplane performance. To achieve accurate and rapid reconstruction of holographic load distribution, a machine learning load-reconstruction model based on Attention Neural Processes is proposed. This model performs spatiotemporal modeling of seaplane water load utilizing sparse sensor data. It directly learns the load patterns across multiple time steps and employs Attention modules to capture the spatial distribution of load. Comparisons with alternative methods demonstrate the model's superior ability to simultaneously capture spatial and temporal dependencies of the unsteady load data. In addition, the model's robust generalization capability is also validated by reducing the number of sensors in the training data. The results indicate that the proposed model exhibits high prediction efficiency, accuracy, and generalization for the reconstruction of unsteady water load distribution, which is of great significance for comprehensively evaluating the hydrodynamic performance of seaplanes. [ABSTRACT FROM AUTHOR]

The landing of a seaplane on the wave is a crucial issue with practical engineering applications in the fields of aeronautical and ocean engineering. The safe landing of seaplanes on wave surfaces prompts an urgent investigation on further understanding the mechanism by which the wings affect loads. This study examines the slamming force characteristics, pressure distributions, and free surface profiles of a two-dimensional seaplane section with varied heel angles into waves, considering different entry velocities, entry locations, and wave steepnesses. The overset mesh technique has been integrated into the waves2Foam toolbox to achieve a numerical wave tank based on the overset mesh. Numerical results for the vertical slamming force, slamming pressure coefficient distribution, and free surface profile were validated against published semi-analytical solutions and laboratory tests. The slamming force during the water entry of the seaplane section under the wave effect shows similar but more complex characteristics than those of the wedge section, manifesting as a phenomenon of multiple peaks. In addition to the bottom slamming of the airframe, localized high-pressure regions appear beneath the wing due to the combined squeezing effect on the air layer by the wing and water particle, which is similar to the wing-in-ground (WIG) effect. Slight sawtooth fluctuations of the wavefront were observed as a consequence of the disturbance of the air layer by the wings. [ABSTRACT FROM AUTHOR]

The closure of Sydney's Powerhouse Museum has sparked debates about the removal of its largest exhibit, the Catalina seaplane Frigate Bird II. Despite its limited historical significance, the aircraft has become popular among the public. Australian public museums have generally shown disinterest in aviation history, with only one original aircraft acquired in the past 25 years. The museum's interpretation of the plane's pilot and flight has been mythologized, and the significance of the aircraft is being questioned. The article suggests that when the Catalina returns, a display based on evidence-based research should be presented. [Extracted from the article]

Seaplane operations connect remote areas, promote tourism, and provide unique transportation solutions. After many years of preparations, commercial seaplane operations on a network of 100 water airports and 200 waterways in Greece are about to commence. The network can serve the needs of 1.6 million permanent residents of the Greek islands, the inhabitants of the mainland, and over 35 million annual tourists. This paper aims to conduct a PESTLE (Political, Economic, Social, Technological, Legal, and Environmental) analysis to identify the factors that have delayed operations and those that will affect the success of future operations. As such, 26 factors are examined. It was found that the Greek debt crisis and the COVID-19 pandemic were impediments to operations. The potential of using electric seaplanes is discussed. Recent developments in using drone inspection capabilities for aviation safety are examined. Management strategies for the Etesian winds and other environmental issues are presented. Overall, seaplane operations have enormous potential, while the Greek economic recovery provides favorable conditions for completing the project. The critical issue determining success is executing a multi-faceted business model to ensure seaplane operations’ financial viability. The network can act in synergy with other modes of transportation to help achieve social cohesion, improve tourism services, and foster economic development.

This document is a comprehensive resource on seaplane safety and accidents. It includes links to FAA aviation safety information, seaplane safety guidelines, and general aviation activity surveys. The document also provides research articles and studies on seaplane accidents, risk assessment, and pilot analysis. It presents figures and tables showing the number of seaplane accidents, fatalities, and flight time over the years. The document highlights the top accident event sequences and causes for both seaplanes and non-seaplanes. Overall, it is a valuable source for anyone researching seaplane safety and accidents. [Extracted from the article]

The electric seaplane, designed for take-off and landing directly on water, incorporates additional structures such as floats to meet operational requirements. Consequently, during the take-off taxiing phase, it encounters significantly higher aerodynamic and hydrodynamic resistance than other aircraft. This increases energy demand for the electric seaplane during the take-off phase. A mathematical model for energy consumption during this stage was developed by analyzing resistance, using the propeller pitch angle as an optimization variable. This study proposes a coupled energy efficiency optimization method for the take-off phase of an electric seaplane's electric propulsion unit (EPU). The method aims to determine an optimal propeller pitch angle configuration aligned with the seaplane's design criteria. This ensures that the propeller output thrust meets minimal requirements during take-off while enhancing energy efficiency. Experimental validation with the two-seater electric seaplane prototype RX1E-S has demonstrated that selecting the optimal propeller pitch angle can effectively reduce energy consumption by approximately 10.4%, thereby significantly enhancing flight efficiency. [ABSTRACT FROM AUTHOR]

In this paper, the ditching performance of a seaplane model on calm water and a uniform water current coupled with wind was numerically investigated. The overset grid technique was applied to treat the large amplitude of the body motions of the seaplane without leading to mesh distortion. The effects of the initial velocity and the initial pitch angle on the slamming loads and motion responses were investigated for the seaplane's ditching on calm water. A good agreement with the experimental data on the velocity and angle was obtained. Besides ditching on calm water without the water current and wind, three more-complicated conditions were adopted, including the seaplane's ditching on calm water with wind, a water current without wind, and a water current coupled with wind. The accelerations and impact pressures of the seaplane can be influenced by the wind or current. Water splashing and overwashing could be observed during the water entry process, with water overtopping the seaplane head or nose and flowing over the body surface. It can be concluded that the relative motion between the water and the seaplane model should be carefully controlled to avoid possible damages caused by the occurrence of overwashing. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chilena de Antropologia is the property of Universidad de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high-speed motion of a seaplane involves the coupled hydrodynamic and aerodynamic effects. The suction force, pressure, free surface and motion of the seaplane model were numerically investigated to understand the characteristics of the seaplane's planing motion. The study utilized the SST-DDES turbulence model to analyse the coupled hydrodynamic and aerodynamic effects. Overset mesh method and rigid body motion were employed to simulate the high-speed and substantial motion of seaplane. The volume of fluid method (VOF) was used to capture and sharpen the interface between water and air. First, verification and validation (V&V) were performed by comparing the results with those of the towing tank experiments. Second, the air-water entrainment in calm water and free surfaces were presented, and the pressure distribution on the seaplane was analysed and discussed. Numerical simulations were performed while considering the wave parameters of different velocities, wavelengths, and wave heights. The accelerations of the fore, aft, and centre of gravity of the seaplane demonstrated the presence of the suction effect. The evolution of the air-water entrainment at the bottom of the fuselage was observed. The investigation of suction characteristics revealed that the aerodynamic force in waves plays a substantial role in influencing motions of the seaplane. [ABSTRACT FROM AUTHOR]

Compared to the study of shipwrecks, the investigation of submerged aircraft is relatively recent in underwater archaeology. With the passing of time and the addition of World War II (WWII) sites to historical registers, the inclusion of aircraft in the Sunken Military Craft Act of 2004, and the continued expansion of the Defense POW/MIA Accounting Agency's (DPAA) mission to recover lost pilots and crew, these studies have become increasingly important to a variety of stakeholders. Site formation process (SFP) studies stipulate that a crucial aspect of the accurate investigation and interpretation of a site first requires a thorough understanding of the processes that created and subsequently altered the site. For terrestrial archaeologists and maritime archaeologists studying shipwreck sites, a well-established database of such knowledge already exists. For submerged aircraft, however, this database is small, yet growing. This paper will contribute to the understanding and interpretation of submerged aircraft sites through the study of the processes that created and subsequently affected a submerged WWII-era PB2Y Coronado aircraft located in Tanapag Lagoon, Saipan, Commonwealth of the Northern Mariana Islands. Archaeological and historical evidence is examined through the lens of SFP studies to identify the specific aircraft, determine its cause of crash, and understand cultural and natural factors that have impacted the site and may affect it today. [ABSTRACT FROM AUTHOR]

Featured Application: Provides mitigating strategies for amphibious aircraft accidents. Causes and contributing factors of amphibious airplane accidents are examined by comparing the proportion of fatal accidents for different causes of accidents, with a focus on landings on water and low-level flying maneuvers. A set of 183 accidents involving amphibious planes from 2005 to 2020 was extracted from the National Transportation Safety Board's online database. Amphibious airplane accidents are reported to be fatal in 34% of cases, which is higher than the average of 20% for general aviation. Logistic regression analysis shows that the maneuvering flight phase and decision-making factors are significantly more often associated with fatal accidents than other flight phases and causes. In addition, the number of accidents associated with decision-making factors significantly increased during the studied time period. Amphibious airplanes benefit from accident analysis despite the absence of denominator data and the limitations of most general aviation accident reports. Intentional low-level flying is shown to be a central area of concern that may be addressed at the operational as well as the training level. Landing accidents could be avoided by introducing additional warning systems and training regarding (retractable) landing gear as well as general awareness training of decision-making during landings on water. [ABSTRACT FROM AUTHOR]

Mangrove ecosystems, amongst the most productive and biologically complex on Earth, are being degraded worldwide, and their widespread decline during the past decades has affected vital ecosystem services. Mangroves at Koggala lagoon on the southern coast of Sri Lanka have been degraded at an alarming rate due to agricultural practices, coastal zone development, and tourism activities. Most of the banks are heavily eroded due to boat and sea plane activities, and the mangrove ecosystem has been significantly damaged. Implementation of a scientific rehabilitation project was needed to restore this degraded mangrove ecosystem, and research was carried out to enrich the mangrove community by re-establishing mangroves on the eroded banks using corrosion-resistant plastic barrels. The sustainability of replanted mangroves was monitored under phase one and the re-establishment of ecological functions in the mangrove community was monitored under phase two. The accumulated biomass carbon during the period of two and half years was calculated by an allometric equation suggested for calculating biomass carbon of mangroves using the girth and height of individuals. The highest rate of girth increment was observed by the 24th month from establishment, whilst the growth rate declined between the 18th and the 30th months. During the study period, the average above-ground and below-ground biomass per barrel showed a linear increment. Our case study showed that the new method used for restoration is successful in establishing mangroves in sites with high erosion. This restoration technique was successful in coping with the situation in Koggala lagoon where previous restoration attempts were failures. Thus, we recommend this restoration method for sites facing the threat of severe erosion. [ABSTRACT FROM AUTHOR]

Copyright of Riwayat: Educational Journal of History & Humanities is the property of Riwayat: Educational Journal of History & Humanities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

INTRODUCTION: Recently, an analysis of canadian seaplane accidents terminating in water (1995-2019) was conducted, but ultralight water accidents were excluded due to differences from general aviation operations. This is the first literature that reports a series of ultralight accidents that occurred in water. The purpose of this paper is to identify the circumstances surrounding ultralight water accidents in canada and to identify actions with the potential to improve survival. METHODS: Ultralight water accidents that were reported to the transportation safety Board of canada between 1990 and 2020 were reviewed. RESULTS: Of the 1021 accidents that involved ultralights, 114 terminated in water, involving 155 occupants and 8 fatalities, yielding an occupant mortality rate of 5%. Of the accidents, 52% occurred during landing. There was less than 15 s warning in 78% of cases, which included five (63%) fatalities. The aircraft inverted in 40% of the accidents and, in 21%, it sank immediately. loss of control was the terminal cause of the accident in 43% of cases, while adverse environmental conditions were reported in 38% of accidents. Little or no details were included on lifejacket or restraint harness use, status of emergency exits, water temperature, or occupant diving experience or underwater escape training. CONCLUSIONS: The mortality rate in ultralight aircraft water accidents was less than half that of helicopter and seaplane ditchings, but the lack of warning time was similar. All pilots and passengers need to have a well-practiced survival schema before strapping in and can benefit from underwater escape training. [ABSTRACT FROM AUTHOR]

Seaplanes as a transport mode provide the flexibility of using land and water infrastructure for their operations. This functionality presents an opportunity for regions with water surfaces, especially when the sea and air connectivity are the only options. This paper presents an exploratory analysis of seaplanes' potential as a mode of transport in Greece. After reviewing the topics of air connectivity, remote regions and the coexistence of modes of transport, a survey is designed to collect information on the perspectives of potential users in the Greek region. In total 200 replies of residents and non-residents of the country are collected and reflect a social perspective of seaplane operations. It is found that the main aspects that would motivate passengers to choose seaplanes would be the offered trip duration, the ticket price and the trip convenience. The collected information is used for the elaboration of SWOT analyses that assess seaplane operations at a strategic decision-making level in transport planning and technology management. The analysis concludes that the potential of seaplanes as a transport mode lies on the enhancement of sustainable transport, the connectivity of isolated regions and their economic growth. [ABSTRACT FROM AUTHOR]

Relying on previously unexploited archival material, this article examines civil aviation policy initiatives and debates among various stakeholders in London and West Africa—the Colonial Office, the Air Ministry, colonial governments, and civil aviation stakeholders, notably, Sir Alan Cobham and Sir Sefton Brancker, in the inter-war period. The study is situated in the interwoven contexts of the change in use of aircraft from combat to recreation and commerce, inter-departmental rivalry in the colonies, inter-war economic vicissitudes, Anglo-French aviation rivalry in West Africa (the "Second Scramble") and the administrative interface between London and the colonies. This essay extends the literature on civil aviation in British colonial Africa beyond the settler colonies of Kenya, Rhodesia, and South Africa. It also focuses on the neglected early beginnings of civil aviation development in inter-war West Africa. Ultimately, financial considerations stymied colonial aviation projects till after World War II. [ABSTRACT FROM AUTHOR]