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When Japan attacked European and U.S. possessions in the Asia-Pacific region in December 1941, the Australian government had on order more combat-ready operational aircraft from American firms than from Australian and British industries combined. The U.S. was thus critical to the equipping and expansion of the Royal Australian Air Force. This article demonstrates that the framework of imperial defense provided a means by which the Australian government sought to secure American supply, although pressures on U.S. industry ultimately delayed the Australia air force's modernization and expansion program in 1940-1941. The war with Japan nonetheless created the potential for a more direct Australian-American relationship. [ABSTRACT FROM AUTHOR]

During the Second World War, Australia received almost $2 billion worth of Lend‐Lease aid from the United States — the largest foreign debt ever incurred by the Commonwealth. The settlement terms for this debt, however, were never defined or discussed during that conflict, remaining "an uncertain obligation to be assessed by an unknown person on an unspecified day of judgment."2 This paper examines the economic, military, and geopolitical factors that shaped Australia's Lend‐Lease Settlement Agreement of June 1946. It focusses on the military aircraft which accounted for a quarter of this foreign debt. The least saleable of all Lend‐Lease surpluses, these also proved the most challenging for US and Australian negotiators. Having contested initial US claims and secured sizeable debt reductions, Lend‐Lease settlement was trumpeted by the Chifley government as a great diplomatic success. Findings from this investigation indicate instead that Australia's Lend‐Lease settlement terms were restrictive, and possibly punitive, having been substantially determined by US domestic and partisan‐political considerations. Moreover, these details and their significant implications were withheld from the public, the media, and the parliamentary opposition in the months leading to the September 1946 federal election. [ABSTRACT FROM AUTHOR]

During the Second World War, Australia received almost $2 billion worth of Lend‐Lease aid from the United States — the largest foreign debt ever incurred by the Commonwealth. The settlement terms for this debt, however, were never defined or discussed during that conflict, remaining "an uncertain obligation to be assessed by an unknown person on an unspecified day of judgment."2 This paper examines the economic, military, and geopolitical factors that shaped Australia's Lend‐Lease Settlement Agreement of June 1946. It focusses on the military aircraft which accounted for a quarter of this foreign debt. The least saleable of all Lend‐Lease surpluses, these also proved the most challenging for US and Australian negotiators. Having contested initial US claims and secured sizeable debt reductions, Lend‐Lease settlement was trumpeted by the Chifley government as a great diplomatic success. Findings from this investigation indicate instead that Australia's Lend‐Lease settlement terms were restrictive, and possibly punitive, having been substantially determined by US domestic and partisan‐political considerations. Moreover, these details and their significant implications were withheld from the public, the media, and the parliamentary opposition in the months leading to the September 1946 federal election. [ABSTRACT FROM AUTHOR]

This article measures and discusses the continuities and changes in the procurement process in Europe by examining the influence of national preferences in terms of sovereignty, industrial issues, and strategic needs on procurement strategies. We focus on the aerospace defense industry and study four aircraft markets (fighter aircraft, transport aircraft, helicopters, and UAVs) in 30 European countries during the post-Cold War era. Our results reveal significant heterogeneity in terms of strategies. They suggest that European countries lack coordination in their aircraft procurement strategies; if a country has sufficient industrial capacity, it will seek to maximize national industrial benefits in its procurement choices, to the detriment of its European partners; conversely, if a country has no industrial capacity, transatlantic suppliers would be preferable to European ones. Members of the former USSR and Warsaw Pact have phased out old Soviet-era aircraft at different rates, depending on the market, with European suppliers benefiting more from this process than American ones. Overall, our study provides a comprehensive and nuanced perspective on the defense aircraft industry in Europe that can inform policymakers and stakeholders in this sector. [ABSTRACT FROM AUTHOR]

This paper reports on the archaeological recording and recovery of a MK II Fairey Barracuda from the Solent, Hampshire, off the south coast of England. As its location precluded the aircraft being left in situ, the decision was made to recover the aircraft. Despite adverse visibility, and a significant amount of overburden, the extant remains of the aircraft were successfully recovered and delivered to the Fleet Air Arm Museum for conservation, as part of an ongoing project to rebuild an example of a Fairey Barracuda. In being recovered for reuse and exhibition some of the Barracuda's value to the wider community changed from that of a lost military aircraft to that of an historic object, drawing out the social history around it, and giving insights into military aircraft construction during the World War II. [ABSTRACT FROM AUTHOR]

This study explores the operational implications and safety considerations of using non-primary fuels—AVGAS, MOGAS, and F76 Dieso—in military transport aircraft, against the backdrop of standard aviation fuels. Through an analysis of fuel properties such as vapor pressure, density, viscosity, freeze temperature, water solubility, and thermal conductivity, this work outlines the operational envelopes for the mentioned non-primary fuels, highlighting the temperature and altitude limitations inherent to their use. The evaluation underscores the necessity of relevant testing, certification, and adherence to operational guidelines and constrains to ensure aircraft safety and reliability when standard fuels are unavailable, and hence, non-primary fuels may be required in special missions under emergency. Key findings include the specific altitude and temperature limitations for AVGAS and MOGAS to prevent fuel freezing and boiling, as well as the operational challenges posed by F76 Dieso due to its higher density and viscosity. The study also addresses the importance of managing water content in the fuel system, the flammability range of the non-primary fuels, and the considerations for fuel mixing to maintain aircraft performance and safety standards. This analysis aims to enhance the understanding of non-primary fuel usage in military transport aircraft, providing insights for system design, performance assessment, and the development of operational procedures to support military aviation in diverse operational scenarios. [ABSTRACT FROM AUTHOR]

Calculating the steering moment of friction at the nose landing gear wheel of the military training aircraft, using calculus programs such as Mathcad, allows practical experience to be retained, and encourages its dissemination for similar calculations in the future. Two methods are presented: an empirical, but very fast method, and an analytical as highly accurate method. The aim of this calculation is to dimension the active moment developed by the steering actuators so that it is at least 1.5 times the calculated resisting moment opposing the steering action. The total steering moment of friction at the nose landing gear wheel is generated by the frictional forces between the wheel and the running way. [ABSTRACT FROM AUTHOR]

Informed by the concept of plausible deniability and newly-declassified U.S. and Japanese documents, this study explores the interconnectedness between public and private security assurances made during the 1957-1960 revision of the U.S.-Japan Security Treaty. The role of secret agreements is conceptualized as a form of covert operations in U.S.-Japan allied secret diplomacy. The revised security treaty and joint communiques announced by President Dwight D. Eisenhower and Prime Minister Nobusuke Kishi were reinforced by secret agreements. Dual confidential arrangements enabled the transit of nuclear-armed U.S. vessels and warplanes into Japanese territorial waters and airspace, along with the free-use of U.S. bases in Japan for Korean contingencies. The U.S. employed overt and covert mechanisms to preserve its extended deterrent capabilities in East Asia as well as to meet Congressional and military requirements to preserve U.S. base rights in Japan. Japanese officials utilized covert strategies, including concealing the existence of secret agreements, thereby denying alleged public deception and ensuring their political survival for decades. In essence, secret agreements lay at the heart of the U.S.-Japan asymmetric alliance. [ABSTRACT FROM AUTHOR]

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Single-pilot operations are already in place within military aircraft, small modes of commercial passenger transportation, and cargo operations. NASA, aircraft manufacturers, and airlines are collaborating on projects that birth safe and efficient single-pilot operation suitable technology for commercial airliners. A stipulated number of cabin crew is required per number of passengers on commercial airliners for safety, security, and medical purposes. The purpose of this pilot study was to determine what scales are valid to assess factors that affect a cabin crew's willingness to operate on single pilot operations. With the selection of appropriate scales, such findings could aid industry regulators, government bodies, and airlines with training programs, educational conferences, and procedural development. The pilot study surveyed members of the cabin crew population using voluntary response sampling. The cabin crew was presented with a survey that collected demographic data, affect ratings, technology acceptance model perceptions, personality traits, and willingness to operate scores. The validity of the scales was tested using Cronbach's Alpha in SPSS, and the usability of the survey instrument was assessed. The affect scale was shown not to be valid. In a follow-up study, the aim will be to use a survey containing the six remaining valid scales and collect demographic data to determine which predictors will be significant in a regression model. [ABSTRACT FROM AUTHOR]

The Second Circuit's landmark ruling in Jones v. Goodrich Pump & Engine Control Sys., Inc. establishes crucial precedent by asserting that tort claims stemming from military aircraft crashes are not field or conflict preempted by the Federal Aviation Act (the Act). This decision, the first of its kind at the appellate level, carries far-reaching implications. The court's rationale, grounded in the Act's plain language, emphasizes that "public aircraft," including military ones, are exempt from Federal Aviation Administration regulation. Title 49, section 44701(a)(1), explicitly excludes public aircraft from the Act's purview. While the court's analysis relies on the Act's text, it is fortified by a comprehensive examination of legislative history dating back to the early days of aviation. This Note contends that the Second Circuit's reasoning, supported by both statutory language and over a century of legislative evolution, should serve as a universally adopted guideline. The separation of civil and military aircraft regulation, initiated in the Paris Convention of 1919 and continued through subsequent legislative acts, underscores the distinct standards governing military aviation. The inherent divergence in purpose and design between civil and military aircraft, coupled with Congress's consistent exclusion of military aircraft from FAA regulation, solidifies the argument against preemption. As the sole appellate authority on this matter, the Jones decision provides a robust foundation for future courts facing Federal Aviation Act preemption challenges in "public aircraft" tort cases. [ABSTRACT FROM AUTHOR]

The article presents the discussion on George Chapman's 1616 translation of Musaeus's ‘The Divine Poem of Musaeus' and its connection to his broader translation project of Greek literary works. Topics include Chapman's return to Musaeus's erotic epyllion, his adoption of Musaeus's outdated designation as the "First of all Poets"; and the impact of this assumption on his poetic theory and practice.

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. 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 purpose of this paper is to assess the influence of a novel type of vortex creation device called the leading-edge vortex controller (LEVCON) on the aerodynamic characteristics of a fighter jet. LEVCON has become a trending term in modern military aircraft in recent years and is a continuation of an existing and widely used aerodynamic solution called the leading-edge root extension (LERX). LEVCON is designed to operate on the same principles as LERX, but its aim is to generate lift-augmenting vortices, i.e., vortex lift, at higher angles of attack than LERX. To demonstrate the methodology, a custom delta wing fighter aircraft is introduced, and details about its aerodynamic configuration are provided. The LEVCON geometry is designed and then incorporated into an existing three-dimensional (3D) model of the aircraft in question. The research is conducted using OpenFOAM 8, a high-fidelity computational fluid dynamics (CFD) open-source software. The computational cases are designed to simulate the aircraft's flight at stall velocities within a high range of angles of attack. The results are assessed and discussed in terms of aerodynamic characteristics. A conclusion is drawn from the analysis regarding the perceived improvements in fighter jet aerodynamics. The analysis reveals that both lift and critical angle of attack can be manipulated positively. With the addition of LEVCON, the average lift gain in the high angle of attack (α) range is between 8.5% and 10%, while the peak gain reaches 19.4%. The critical angle of attack has also increased by 2°, and a flatter stall characteristic has been achieved. [ABSTRACT FROM AUTHOR]

Modern aircraft are costly and require heavy investment. It is the same regardless of industries, such as commercial airlines and militaries. It is primarily about maintaining desired readiness by reducing ground time in the militaries, which is critical to maintaining air superiority and winning the war. There are two types of maintenance activities such as preventive and corrective maintenance. Preventive maintenance requires taking action before failures happen. Meanwhile, corrective maintenance reacts to failures, which takes time to buy parts and repair failed components. If we can predict aircraft failures accurately, we will be able to change corrective maintenance activities to preventive maintenance activities, which will reduce aircraft downtime and, thus, increase aircraft readiness or availability. This paper proposes multiple machine learning tools to minimize aircraft downtime to predict aircraft failures with the highest accuracy possible. This paper validates the usefulness of the proposed machine learning tools by experimenting with the actual data obtained from the maintenance record of 33 aircraft operated by the U.S. Air Forces. [ABSTRACT FROM AUTHOR]

With the rapid advancement of modern technology and radar detection systems, electromagnetic (EM) stealth technology has become increasingly significant, particularly in aircraft stealth and military radar applications. In this work, an all-metal metasurface is designed for broadband terahertz radar cross-section (RCS) reduction and infrared invisibility. The all-metal metasurface possesses extremely low infrared emissivity and high polarization conversion in the terahertz band. Through the joint simulation of MATLAB and CST, a genetic algorithm is used to optimize the random phase distribution of 2, 3, and 4-bit metasurfaces, so that the reflected wave is scattered to achieve broadband terahertz RCS reduction. Simulation results show that the metasurface can simultaneously achieve broadband terahertz RCS reduction in 3–5 THz and infrared invisibility in 24–38 THz (8–12.5 μm). The RCS reduction of the coding metasurface is greater than 10 dB compared to the metal plate, and the maximum RCS reduction of the 4-bit metasurface can reach 21.1 dB. Compared to the traditional design method, the proposed method can reduce time consumption and find the optimal result to achieve high performance. We believe the proposed method can provide significant guidance for surface coating in camouflage applications and opens up new possibilities for improving the information capacity of coding metasurfaces. [ABSTRACT FROM AUTHOR]

Compared to maximum state parameters, such as maximum altitude and Mach, the number of hovers and S turns can be used as process parameters representing the complexity of military aircraft maneuvers when classifying big flight mission data to compile flight load spectra for structures. This study developed intelligent statistical algorithms based on yaw angle data from flight parameters such as the number of hovers and S turns. Using the median-crossing de-redundant function of Phase-Sensitive Detection (PSD) and analyzing the characteristics of 360° hovering flight parameters, a statistical algorithm for the number of hovers during a flight profile is presented. Using the split-half function of PSD, a triangle layering algorithm based on the yaw angle signal was developed to count the number of S turns during a flight profile, where the signal of each sublayer is segmented into median-crossing intervals to eliminate the redundant median-crossing marks from the previous layer. Compared with artificial means, the statistical results of the flight example showed that the developed intelligent algorithms are effective. [ABSTRACT FROM AUTHOR]

This paper first presents the results of an experimental study into the damage tolerance of AA7075-T6, which is widely used in both fixed- and rotary-wing aircraft, space structures, and laser bed powder fusion (LBPF) Scalmalloy specimens built by Boeing Space, Intelligence, and Weapons Systems. To this end, four single edge notch AA7075-T6 specimens and four identical single edge notch LBPF Scalmalloy specimens were tested. The resultant crack growth curves reveal that Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy is more damage tolerant than conventionally built AA7075-T6. This finding leads to the observation that the da/dN versus ΔK curves associated with Scalmalloy and conventionally manufactured AA2024-T3 are similar. These findings highlight the potential for Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy to be used to extend the operational lives of military aircraft by the on-demand printing of limited-life Scalmalloy replacement parts. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Recent research has shown that infectious particles in exhaled breath and coughs have a median diameter of about 1 micron. Aerosols in this size range do not contain enough mass to deposit efficiently by gravity so transport is dominated by airflow dynamics. Therefore, airflow patterns in aircraft cabins influence cross-infection risk during passenger transport and open-air high-capacity airlift. METHODS: We developed high-fidelity computational fluid dynamic models to investigate internal cabin flow physics on a range of military air mobility, special operations, and trainer aircraft, including the C-17, KC-135, C-130J, C-5M, KC-46, KC-10, C-146a, and T-1A. Virtual cabin geometries were generated from real world aircraft cabins using a high-definition laser scanner paired with computer aided engineering. Virtual geometries were uploaded to commercial CFD solver Star-CCM+, on an unstructured polyhedral grid. Boundary conditions for inlet and outlet vents were defined based on either manufacturer provided values or direct measurements for mass flow rates and pressurization during flight. The steady Reynolds Averaged Navier Stokes equations were solved, with the SST K-Omega turbulence model. Airflow patterns were analyzed for flow direction, speed, and compartment-to-compartment transition. RESULTS: Model output indicated that airflow patterns significantly varied airframe to airframe and were dependent on both the locations and configuration of the inlet and outlet vents. Air mass movement direction and efficiency was highly recirculatory in most aircraft, particularly in compartments with relatively large volume to mass flow ratio. DISCUSSION: CFD models of airflow patterns provide critical information needed to implement protective actions to mitigate cross-infection on each airframe. In follow- on studies, these models may be manipulated in a high-throughput manner to mimic different cargo and passenger scenarios during different phases of flight. Further, bioaerosols can be introduced to evaluate dispersion, deposition, and removal from the aircraft for different airflow dynamics and bioaerosol release locations. Learning Objectives 1. Computational simulations can be used to predict airflow patterns and corresponding cross-infection risk in aircraft compartments. 2. Airflow patterns in aircraft are unique by airframe and are highly dependent on the locations and configuration of inlet and outlet vents where the vent configuration may vary based on mission requirements. [ABSTRACT FROM AUTHOR]

From Jim March we learned that organizational intelligence demands adaptation to the needs of a distant future as well as the efficient use of resources in the present. Commitment to new ideas that deviate from norm is necessary for long-term adaptation, but comes with great uncertainty as to if when or how success will come. This article uses a historical study of military aircraft manufacturer Saab to explore the transition from experimenting with physical models and dangerous test flights in the development of rather simple aircraft systems, to the development of complex integrated aircraft systems using virtual models that can be tested in a simulated world, thereby postponing choice and the need for commitment of resources in the physical world. We show how modeling techniques and tools were developed over five generations of aircraft to help developers represent and evaluate alternative ideas, in an increasingly realistic virtual reality, thereby reducing material and fatal consequences in aircraft development. We distinguish hybrid forms of evaluation and a transition that seems to be moving in the direction of "virtual online evaluation," where empirically informed simulation models, based on real flight data reduces the fidelity gap between reality and representation. Drawing upon a selection of Jim March's writings, we speculate what this transition implies for learning from experience and the possibility of foolishness without consequence. [ABSTRACT FROM AUTHOR]

The aircraft tire is a complex, composite product of vital importance to all aircraft composed of rubber compounds (elastomers), fabric materials (nylon, aramid, or Kevlar), and steel wires (wire beads). The aircraft tire is subjected to very high mechanical stresses during parking, takeoff, and especially on landing, various thermal demands, solar radiation, the action of ozone, and partial discharge of the electrostatic charges accumulated on the outer surface of the aircraft. From the construction point of view, tires are bias tires or radial tires. Most aircraft tire companies recommend inflating their tires with nitrogen because it keeps out moisture, protects against corrosion, promotes compatible pressure, and is nonflammable. The selection of aircraft tires is made according to the stress to which tires are subjected and according to the recommendations of aircraft tire companies, based on the application of the Taguchi classification and the AHP multicriteria analysis methodology. [ABSTRACT FROM AUTHOR]

Background: Exposure to high-performance flight stresses the vestibular system and may lead to adaptive changes in the vestibular responses of pilots. We investigated the vestibular-ocular reflex of pilots with different histories of flight exposure both with respect to hours of flight and flight conditions (tactical, high-performance vs. non-high-performance) to evaluate if and how adaptative changes are observable. Methods: We evaluated the vestibular-ocular reflex of aircraft pilots using the video Head Impulse Test. In study 1, we assessed three groups of military pilots: Group 1 had 68 pilots with few hours of flight experience (<300 h) in non-high- performance flight conditions; Group 2 had 15 pilots with many hours of flight (>3,000 h) and regularly flying tactical, high-performance flight conditions; Group 3 had eight pilots with many hours of flight (>3,000 h) but not exposed to tactical, high-performance flight conditions. In study 2, four trainee pilots were followed up and tested three times over a 4-year period: (1) <300 h of flight on civil aircraft; (2) shortly after exposure to aerobatic training and with <2,000 h of overall flight; and (3) after training on tactical, high-performance aircraft (F/A 18) and for more than 2,000 h of flight. Results: Study 1: Pilots of tactical, high-performance aircrafts (Group 2) had significantly lower gain values (p<0.05) as compared toGroups 1 and 3, selectively for the vertical semicircular canals. They also had a statistically (p = 0.022) higher proportion (0.53) of pathological values in at least one vertical semicircular canal as compared to the other groups. Study 2: A statistically significant (p < 0.05) decrease in the rVOR gains of all vertical semicircular canals, but not of the horizontal canals, was observed. Two pilots had a pathological value in at least one vertical semicircular canal in the third test. Discussion: The results evidence a decrease in the gain of the vestibular- ocular reflex as measured with the video head impulse test for the vertical canals. This decrease appears to be associated with the exposure to tactical, high-performance flight rather than with the overall flight experience. [ABSTRACT FROM AUTHOR]

In this study, effects of high-pressure compressor pressure ratio (HPC PR) and bypass ratio (BPR) regarding adaptive cycle turbofan (ACT) engine on performance parameters and second law parameters of thermodynamics involving Carnot, Curzon–Ahlborn, Caputo, thermal and exergy efficiencies are dealt with. For this aim, HPC PR changes between 4 and 6, and bypass ratio ranges between 0.3 and 0.6. At same altitude of 10,000 m, comparative analysis is performed for efficiency behavior of ACT engine at military mode (MM) and afterburner mode (ABM). Better understanding of performance improvements of a military aircraft can be possible by investigating these efficencies for different design variables. Based on these computations, environmental and irreversibility parameters involving specific irreversibility production and environmental effect factor regarding ACT engine are dealt with at both modes. According to performance outcomes, SFC of the ACT engine decreases by 7.66% at MM, whereas it increases by 0.34% at ABM due to higher BPR. Moreover, it diminishes by 4.98% at MM and decreases by 0.42% at ABM with influence of the elevated HPC PR. As for efficiency analyses, exergy efficiency of ACT engine increases from 20.04 to 21.7% at MM, whereas it decreases 17.43 to 17.37% at ABM with effect of raised BPR. The higher HPC PR leads to increase from 20.32 to 21.38% at MM and from 17.39 to 17.46% at ABM. Among the components, the combustor has the lowest exergy efficiency, which is favorably affected from both variables at MM. Finally, environmental effect factor of the ACT becomes lower thanks to the higher BPR and HPC PR at MM. However, at ABM, to increase these variables do not result in lower EEF. Therefore, considering design parameters according to operation modes could lead in finding more meaningful outcomes. It is thought that this study helps in analyzing of thermodynamic parameters with respect to different design parameters. [ABSTRACT FROM AUTHOR]

Aircraft detection in remote sensing images is an important branch of target detection due to the military value of aircraft. However, the diverse categories of aircraft and the intricate background of remote sensing images often lead to insufficient detection accuracy. Here, we present the CNTR-YOLO algorithm based on YOLOv5 as a solution to this issue. The CNTR-YOLO algorithm improves detection accuracy through three primary strategies. (1) We deploy DenseNet in the backbone to address the vanishing gradient problem during training and enhance the extraction of fundamental information. (2) The CBAM attention mechanism is integrated into the neck to minimize background noise interference. (3) The C3CNTR module is designed based on ConvNext and Transformer to clarify the target's position in the feature map from both local and global perspectives. This module is applied before the prediction head to optimize the accuracy of prediction results. Our proposed algorithm is validated on the MAR20 and DOTA datasets. The results on the MAR20 dataset show that the mean average precision (mAP) of CNTR-YOLO reached 70.1%, which is a 3.3% improvement compared with YOLOv5l. On the DOTA dataset, the results indicate that the mAP of CNTR-YOLO reached 63.7%, which is 2.5% higher than YOLOv5l. [ABSTRACT FROM AUTHOR]

Much of the literature on military aircraft unit costs is based on US data. This article adds to our knowledge by using an original data set for UK military aircraft costs, profits and prices. A distinction is made between unit costs within a generation of aircraft and between generations. Four research questions are addressed. First, is the UK aircraft industry a decreasing cost industry; second, are new entrants higher cost suppliers; third, what is the evidence on profitability in war and peace and between new entrants and original developers; fourth, what is the UK evidence on Augustine-type cost escalation and on the efficiency of aircraft procurement in war and peace? The UK aircraft industry was found to be a decreasing cost industry reflecting both scale and learning economies. Typically, new entrants were higher cost suppliers and profit rates were higher in peace-time. There was substantial Augustine cost escalation for UK combat aircraft and doubts are raised about the efficiency of military aircraft procurement. [ABSTRACT FROM AUTHOR]

The study focuses on testing a simplified way of estimating the resultant force due to ballistic impacts resulting in a full fragmentation of the impactor with no penetration of the target. The method is intended to be useful for the parsimonious structural assessment of military aircrafts with integrated ballistic protection systems by means of large scale explicit finite element simulations. The research investigates the effectiveness of the method in allowing the prediction of the fields of plastic deformation collected by hard steel plates impacted by a wide range of semi-jacketed, monolithic, and full metal jacket.308 Winchester rifle bullets. The outcomes show the effectiveness of the method being strictly related to the full compliance of the considered cases with the bullet-splash hypotheses. The study therefore suggests the application of the load history approach only after careful experimental investigations on the specific impactor–target interactions. [ABSTRACT FROM AUTHOR]

The importance of this research is that it mainly describes the various interesting areas of the thermodynamic aspects of a gas generator for application in aircraft. The gas generators are widely used for both civil and military applications. Thermodynamics is the branch of science that deals with energy being transformed into work and vice versa. The demand for gas generator and its applications continuously increases in the areas of aerospace and aeronautical technologies. Gas generating device involves creation of a high temperature and pressurised combustion of gas by burning propellant in cartridge. These devices are filled with energetic materials (EMs) and used to perform a critical operation in an emergency under adverse conditions by releasing energy very quickly in milliseconds. A data acquisition system (DAS) is used to verify the gas generator’s performance parameters such as peak pressure (Pmax) and time to maximum pressure (TPmax) generated in the closed vessel (CV). A double-base propellant consisting of fuel, oxidizer and other ingredients are used as the medium for gas generation. The main goal of this research paper is to establish various relationships and determine the various thermodynamic properties of a gas generator for application in aircraft. The experimental findings from this research show the specific heat of propellant is 0.3488 cal/g/°C, the calorimetric value to equal 925 cal/g, the force constant to be 1052 J/g, the co-volume to be 0.989 m³ /kmol and the flame temperature to be 2944 K. The thermodynamic analysis of a gas generator for military applications plays a significant role in the design and development phase [ABSTRACT FROM AUTHOR]

In aviation, any detail can have massive consequences. Among the potential sources of failure, human error is still the most troublesome to handle. Therefore, research concerning the management of mental workload, attention, and stress is of special interest in aviation. Recognizing conditions in which a pilot is over-challenged or cannot act lucidly could avoid serious outcomes. Furthermore, knowing in depth a pilot's neurophysiological and cognitive–behavioral responses could allow for the optimization of equipment and procedures to minimize risk and increase safety. In addition, it could translate into a general enhancement of both the physical and mental well-being of pilots, producing a healthier and more ergonomic work environment. This review brings together literature on the study of stress and workload in the specific case of pilots of both civil and military aircraft. The most common approaches for studying these phenomena in the avionic context are explored in this review, with a focus on objective methodologies (e.g., the collection and analysis of neurophysiological signals). This review aims to identify the pros, cons, and applicability of the various approaches, to enable the design of an optimal protocol for a comprehensive study of these issues. [ABSTRACT FROM AUTHOR]

The length of the supersonic jet ejected from the military aircraft must be reduced in order to decrease its heat signature and aeroacoustic noise and thereby to enhance its stealth capability. The reduction or manipulation of the supersonic core can be achieved through various passive control techniques. Considering this, the present study explores the mixing characteristics of supersonic jets with and without passive controls. Passive controls in the form of grooves configured at the exit of a Mach 1.73 convergent–divergent nozzle are investigated computationally. Particularly, the supersonic jet decay characteristics and flow development for a plain nozzle and a nozzle with semi-circular, square, and triangular grooves are presented. In addition, the study explores different turbulence models, namely, Spalart–Allmaras, realizable k-ε, std k-ω, shear stress transport (SST) k-ω, and SST transition. The realizable k-ε turbulence model is found to be the most effective one in capturing the supersonic jet structure. It is observed that the grooves produce large distortions in the jet structure, accompanied by significant mass entrainment and lateral spread. Interestingly, semi-circular grooves are proven to be most effective in all cases of expansion level than square and triangular grooves. For the semi-circular grooves, a maximum of 48.5% reduction in the supersonic core length of the correctly expanded jet at nozzle pressure ratio (NPR) of 5 is achieved. The reduction in the supersonic core length for semi-circular grooves is 31% for the overexpanded jet at NPR 4 and 29% for the underexpanded jet at NPR 7. [ABSTRACT FROM AUTHOR]

Based on the adjoint method, the afterbody of a military transport aircraft was optimized and designed to meet engineering constraints under real flight conditions. Guidance for the key design parameters of the afterbody of the military transport aircraft is given. The vortex dynamics and boundary layer extraction methods were used to analyze the optimization results of military transport aircraft. It was found that, upstream of the vortex shedding point, the circumferential accumulation process of the vorticity is weakened. The position of the vortex shedding and the appearance of the saddle line are delayed by reducing the circumferential inverse pressure gradient and the intensity of the crossflow. The afterbody vortex system of the optimized configuration is further away from the surface. Meanwhile, the distance between the counter-rotated vortex decreases, and the upwashing speed of the vortex core is smaller. Therefore, vortex-induced drag is reduced. Finally, compared with the initial configuration, the optimized configuration has a relative drag reduction of 23.2%. [ABSTRACT FROM AUTHOR]