Military Aircraft Research Articles

Retraction To: Novel Approach for Detecting the Neurological or Behavioral Impact of Physiological Episodes (Pes) in Military Aircraft Crews

Retraction To: Novel Approach for Detecting the Neurological or Behavioral Impact of Physiological Episodes (Pes) in Military Aircraft Crews

Acoustic Shock Formation in Noise Propagation During Military Aircraft Ground Run-Up Operations

A distinctive feature of many high-amplitude jet noise waveforms is the presence of acoustic shocks. Metrics indicative of shock presence, specifically the skewness of the time derivative of the waveform, the average steepening factor, and a new wavelet-based metric called the shock energy fraction, are used to quantify the strength and prevalence of acoustic shocks within waveforms recorded 10–305 m from a tethered military aircraft. The derivative skewness is more sensitive to the presence of the largest and steepest shocks, whereas the average steepening factor and shock energy fraction tend to emphasize aggregate behavior of the entire waveform. These metrics are applied at various engine conditions, over a wide range of angles and distances, to assess the growth and decay of shock waves. This paper represents the first time that the development of these metrics is shown from the near field to the far field, out to 305 m. The responses of these metrics point to significant shock formation occurring through nonlinear propagation out to 76 m from the microphone array reference position. Although these strongest shocks decay past 35 m, continued shock formation and atmospheric absorption can make the steepened nature of the waveform more prominent out to 305 m.

Flow characteristics and separation control in a transitional twin air-intake

Ambient air is ingested into the engine of military aircrafts using the air-intake system within a limited space. The flow non-uniformity produced in the air-intake creates flow separation and total pressure loss due to the centerline curvature and area diffusion which eventually affects its performance. The current work discusses the performance of a transitional twin air-intake without and in presence of slotted synthetic jets. The synthetic jet is employed just before the inflection at a range of velocity ratio from 1 to 10 and found that for a velocity ratio of 4.0, the pressure distortion at the aerodynamic interface plane is found minimum. Hence, the other performance parameters are computed at that optimized flow condition. The outcome of the study reveal that the static pressure is recovered by 4.61%–6.64% while the total pressure loss is decreased by 59.28%–89.95% using optimized synthetic jets for a range of Reynolds numbers.

The Evolution of Privatization in Brazil: The Case of Embraer

State participation in the economy has been intensely debated over the past three decades. In Brazil, especially after the advent of the Federal Constitution in 1988. Privatization in Brazil, however, was instituted by Law 8.130/90, which established the National Plan for Privatization, aiming at transferring to the private sector activities unduly exploited by the public sector. In this article, we investigated one of the most significant privatizations in Brazilian history, the case of Embraer, the world's third largest civil aircraft manufacturer. Key findings pointed out a complex privatization process, including golden share vetoes and institutional challenges faced by Embraer, such as the first Brazilian company to adopt the International Financial Reporting Standards (IFRS) fully. In addition, the careful analysis suggested implications for the reduction of public debt. Also, the resumption of investments in companies and activities transferred to the private sector, modernization of the country's industrial park, increasing its competitiveness, and reinforcing business capacity in Embraer's jet C-series sector and military aircraft, for instance. Also, implications for the public administration to focus its efforts on actions where the State's presence is necessary for achieving national priorities. Finally, the strengthening of the capital market, as well as the democratization of the ownership of the capital of Embraer are topics to be debated in the present article.

IRNSS Performance Evaluation of SPS Services on Military Aircraft

The essence of this paper is to study and characterise the performance of Indian Regional Navigation Satellite System (IRNSS), also known as NavIC (Navigation with Indian Constellation), in actual dynamic environment by conducting field trials on military aircraft. The dynamic accuracy of IRNSS receiver in terms of position, velocity and altitude has not yet been tested on any aircraft system i.e. commercial or military applications. These field trials and performance evaluation will help in on-field assessment of IRNSS receiver performance with availability of five, six and seven IRNSS satellites. During conduct of trials, IRNSS receiver and IRNSS antenna were placed inside the aircraft. Results analysis of 18 hours flying data depicts position availability of 99.872% with five satellites and 100% position availability with six and seven satellites.

APPLICATION OF INCONEL 718 (IN718) FOR ADVANCED ARMOR MATERIAL AND ITS POTENTIAL IN INDONESIA DEFENSE INDUSTRY

<div><p class="Els-history-head">Indonesia is the world's largest source of nickel ore, controlling 27 percent of the global nickel market. Because of its unique physicochemical properties, such as malleability, high-temperature stability, strength, corrosion resistance, ductility, heat conductivity, and electrical conductivity, nickel is one of the most important metals in the industry. Nickel-based superalloys are commonly utilized to build hot-end components for aviation engines and gas turbines. The purpose of this study is to examine the use of Inconel 718 (IN718) for armor and its prospective development in Indonesia's military industry. The outcome demonstrates IN718's potential in the Indonesian defense industry, with the manufacturing of military aircraft gas turbines, submarines, military electric engines, and high-protection armor vehicles among its most prominent applications. Nickel may be recycled by using a nickel extraction technique like the liquid metal extraction-vacuum distillation (LME-VD), which produces no waste gas or solid and is environmentally beneficial. IN718's development is also by the government's goal of increasing the value-added of Indonesia's nickel production while minimizing environmental impact.</p></div>

Costs and Prices of UK Military Aircraft in War and Peace

ABSTRACT 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.

Observations on comparable aluminium alloy crack growth curves: Additively manufactured Scalmalloy® as an alternative to AA5754 and AA6061-T6 alloys?

• Illustrates the similarity between Scalmalloy and AA5754 and AA6061-T6. • These latter two materials are widely used in automotive vehicles and maritime vessels. • Highlights that Scalmalloy is a viable alternative to AA5754 and AA6061-T6. • The AM community is issued with a challenge to measure the Scalmalloy small crack growth curve. Scalmalloy® has been proposed for use as additively manufactured (AM) replacement aluminium alloy parts for civil and military aircraft, and for AM aluminium parts for use in satellites and space structures. This study builds on the results of a prior investigation to reveal that Scalmalloy® has a crack growth curve similar to those associated with aluminium alloys AA5754 and AA6061-T6, which are widely used in the automotive industry and in maritime vessels. The R = 0.1 d a/ d N versus Δ K curve for small naturally occurring cracks in LPBF Scalmalloy® is also predicted and the additive manufacturing community is challenged to undertake testing to validate or disprove this prediction.

3D Computational Model for an Electrochemical Gas Separation and Inerting System

Aircraft fuel tank inerting is employed to reduce the flammability of the fuel vapor in the ullage (air volume above the fuel) by restricting its oxygen concentration to a safe value—12% for commercial aircraft and 9% for military aircraft. Inerting is typically accomplished by displacing oxygen in the ullage with an inert gas like nitrogen. Electrochemical gas separation and inerting system (EGSIS) is an on-board method to generate and supply nitrogen-enriched air (NEA) to the fuel tank. EGSIS combines a polymer electrolyte membrane (PEM) electrolyzer anode which dissociates water to evolve oxygen, and a PEM fuel cell cathode which reduces oxygen from atmospheric air to produce NEA at its outlet. This paper represents the first attempt to model and simulate EGSIS using a three-dimensional, steady state, isothermal model. Various EGSIS performance indicators such as current density, reactant concentration distribution, and polarization curves are studied as a function of operating conditions and design parameters. The results from the computational model are validated against our previous experimental results for various operating conditions. The simulation results reveal the effects of temperature, reactant flowrates, and material property optimization on EGSIS performance. Different operating strategies are explored with the goal of improving system performance.

MRAC Adaptive Control Design for an F15 Aircraft Pitch Angular Motion Using Dynamics Inversion and Fractional-Order Filtering

This study proposes a fractional adaptive control scheme design for a longitudinal pitch angular motion control of a military F15 aircraft. The aircraft behavior will be forced to follow a chosen model reference in an MRAC (Model Reference Adaptive Control) configuration combined with dynamics inversion technique such that the transient response becomes invariant even in the presence of uncertainties or variations for a reference input by introducing a fractional-order transfer function pre-filter. Based on Lyapunov theory, the updating control law minimizes the error between the plant output and the model reference one. This controller is set in a cascade with a linear dynamic compensator. Simulation results on a military aircraft model with comparison to preceding results illustrate the effectiveness and the superiority of the proposed control strategy.

Maintaining aircraft manufacturing through government purchases: Australia and Canada from the end of the Second World War until the 1970s

In this article, a comparison is provided of the alternative Australian and Canadian government procurement policies for military aircraft in the post-Second World War period. Procurement was used by both governments to maintain manufacturing capacity that was established in the Second World War. By undertaking this analysis, the differing characteristics of the two policies are highlighted. In both cases procurement policies promoted the maintenance of aircraft manufacturing industries, however, the resulting industries were quite different in nature, a result partly of the differing natures of the policies, and different to some degree to the results of the policy in other Western countries.

Hydrodynamic ram analysis in high-speed projectile penetrating into water-filled vessels

Hydrodynamic ram (HRAM) is a phenomenon that occurs when a high-speed projectile penetrates a fluid-filled tank, where the energy transferred to the liquid could result in a catastrophic failure and excessive structural damage. It is essential to take physical comprehension of the hydrodynamic effects that occur during an HRAM event in the civilian domain as well as for the military aircraft design, which would in fact contribute to design better structures with respect to this particular threat. For this present work, the HRAM due to cavity evolution in confined vessels under ballistic impact by projectiles was investigated through theoretical analysis combined with experimental results. Taking the confinement effects due to the limited size of the fluid-filled vessel and corresponding structure deformation into account, a model is proposed to describe the pressure between the liquid and vessel wall along the penetration trajectory based on cavity dynamics analysis. By studying relevant parameters, changes of wall pressure, non-dimensional disturbance range and energy of two extreme containers, (namely, non-pressure resistance containers and rigid containers without deformation) were examined. The results show that the cavitation pressure has less intense peak but much greater temporal extent compared with the pressure generated during the shock stage, thereby the cavity pressure impulse induced by cavity evolution is a non-negligible factor affecting the deformation and failure of a fluid-filled vessel. The aim of the present work is to reveal the mechanism of the pressure acting on the container wall caused by cavity evolution rather than the initial shock wave in an HRAM event, which will help to study the nature of hydrodynamic ram and understand the role of the cavitation pressure in the damage or deformation of liquid-filled vessels under projectile impact.

Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test.

Military aircraft are subjected to variable loads, which are the main cause of initiation and propagation of cracks in the most stressed locations of the airframe. The aim of a Full-Scale Fatigue Test (FSFT) is to represent actual load conditions in such a way that the results obtained are a good representation of the actual loads and may be used as data that give insight into the development of real fatigue damage in critical locations. The FSFT load spectrum is a generalized depiction of the expected service loads and is designed to give an overall good representation of loads exerted on the airframe’s structural elements during operation. Moreover, the discrete method of load application on the structure (exerting loads with hydraulic actuators rather than pressure fields or inertia loads expected in actual operation) may cause some local effects, which may not be present in operation. The proposed usage of direct strain data from the test include such local effects. Moreover, operational loads may vary between individual aircraft, therefore it is crucial to understand the whole process of fatigue crack onset and development in order to determine safe inspection intervals and thereby mitigate risk. This paper presents crack propagation calculations regarding the development of a crack in a critical location of the PZL-130 “Orlik” TC-II aircraft, discovered during FSFT. The discussed crack was found already developed, hence the information about nucleation and initial propagation of the crack was not available. Therefore, there was a need to recreate the whole propagation process by means of numerical estimations using the FSFT results like location of the crack and total life for model validation. Moreover, in order to gather real load data for calculations a dedicated stain gage was installed on the damaged load path to monitor the actual remote strain in the element during the FSFT. This allowed for the definition of load sequence exerted on the damaged element directly during the test rather than estimating it from the general load conditions of the wing. The calculations allowed for the estimation of crack propagation curves from initiation to critical crack length causing fatal damage. The obtained curves allowed to visualize the crack behavior due to applied load and furthermore define initial and recurring inspection intervals for the entire fleet during operation, which allowed to define which cracks could be found before they reach critical size in order to carry out mitigation actions like repair or replacement of the damaged part. The authors present the methodology for load spectrum development based on direct strain measurements and furthermore crack propagation curves estimation, validated with the actual FSFT results, which allowed to propose nondestructive inspection intervals for future operation.

Optimization Study of Nacelle mounting position for Blended-Wing-Body Aircraft

Blended-wing-body aircraft is a new type of aircraft form that has been used in military aircraft. The potential for application in civil aircraft is being explored. Due to its special shape, the blended-wing-body aircraft is difficult to adopt the conventional under-wing engine mounting form, and usually applies the back braced mounting. The engine mounted on the back could cause surge and separation problems, which affects the flow field quality of the whole aircraft. In this paper, the effect of height and axial mounting position on the overall flow field of the aircraft is determined by modelling and calculation of the blended-wing-body aircraft. The effect of airflow separation is analysed. The engine axial mounting position is discovered to have a significant effect on the elimination of flow separation.

Near-field acoustical holography and acoustic power analysis of a simulated, highly heated supersonic jet.

Although near-field acoustical holography (NAH) and acoustic intensity analysis have previously been used to investigate the apparent jet noise sources produced by military aircraft, explicit connections to supersonic jet characteristics cannot be made due to a lack of information about the exhaust plume. To begin to bridge this gap and better understand the source information yielded by NAH, the current study instead applies NAH to a virtual measurement of the near-field pressures of a highly heated laboratory-scale supersonic jet generated by large-eddy simulation (LES). The holographic reconstructions of the pressure, particle velocity, and acoustic intensity are found to match the LES-generated acoustic field well and are used to calculate the acoustic power of the jet. The jet's calculated overall acoustic power is compared to the free-stream mechanical power, resulting in an acoustic efficiency of 1.5%. Ray-tracing of the acoustic intensity to the jet centerline generates an axial distribution of the acoustic power origin, showing that almost all the power originates from the supersonic portion of the flow and with the distribution peak upstream of the potential core tip. Holographic reconstruction of the pressures along the nozzle lipline captures the general spectral shape of the LES-generated pressures, though it underestimates the amplitude.

PPG Industries uses 3D-printing to create seals for military aircraft

In the USA, PPG Industries Inc's aerospace business, which specialises in paints, coatings, sealants and adhesives, recently supplied Lockheed Martin Corp with seals for use on board its C-130J Super Hercules aircraft.

The air confrontation on the Soviet-German front at the beginning of Great Patriotic War viewed through the prism of rivalry of the fighter aircraft designer engineers

Based on materials from domestic archives and other sources this paper deals with issues faced by the Red Army Air Force in 1942 due to the increased German fighters preponderance in some technical features. The delay in speed and climb rate of similar type of Soviet aircraft defined their own defensive posture enemy dominance in air battle. To solve the problem of improving the flight data of domestic fighter aircraft, a set of measures was taken by the leadership of the country - the Peoples Commissariat of the Aviation Industry (PCAI) and aircraft design engineers. The decision to install the engine M-82 on the LaGG-3 fighter designed by S.A. Lavochkin, V.P. Gorbunov and M.I. Gudkov, which had put into serial production before WW II breaking out, happened to be advanced. However, the German designers had been also developing. They developed another modification of the Messerschmitt Me-109 - G. Moreover, a new enemy of military aircraft fighter appeared at the front - the Focke-Wulf FV-190. The created La-5 did not have parity in flight data with these enemy aircraft. Boosting the M-82 engine and installing a direct fuel injection unit on it made it possible to increase engine power and significantly improve the flight data of the La-5. As a result of overcoming a complex of issues, Soviet design engineers managed to create and launch into mass production a competitive La-5FN aircraft that met the requirements of the armed struggle on the Soviet-German front of WW II.

English military aviation terminology as the object of lexicography

This article is dedicated to the English military aviation terminology and its characteristic, the analysis of which is essential for the development of special terminological dictionary. The goal lies in examination of the peculiarities of creation of the dictionary of English military aviation terminology. The author sets the task to analyze the key theoretical issues associated with the development of dictionaries; determine the stages of this process; consider these stages in the context of working on the dictionary of English military aviation terminology. The relevance of this topic is substantiated by the need for various types of terminological dictionaries, namely for the cadets of military aviation universities. The article explores the peculiarities and stages of creating the dictionary of English military aviation terminology. The research and practical lexicographic work lean on the scientific works of Russian and foreign scholars. The dictionary under development is the first attempt to create the terminological resource that incorporates the terms related to the operation of military aircraft (namely helicopters), and the characteristics of the ideographic dictionary and textbook. It will be supplemented with special academic and methodological complex.

Про перспективи розвитку фірми АНТОНОВ у сучасних умовах

The features of the functioning of the domestic aviation industry in the Soviet period and during Ukraine's independence, as well as the world experience of developed countries in supporting aircraft manufacturing companies in the creation of advanced aviation technology are considered. Abroad, such an industry works with the assistance and under the control of the state, including private companies. The main directions of the development strategy of ANTONOV Company in modern conditions are shown. Effective options for ensuring the enterprise activities in the absence of state funding are disclosed, which made it possible to save the domestic school of aircraft engineering and continue the development of new aircraft. The main principles used in the formation of plans and promising directions of ANTONOV Company activity developed, including the priority implementation of state orders, constant monitoring of market needs in aviation technology, the modernization of existing ANTONOV aircraft, the development of aircraft modification families to meet market demands at minimal cost and in a short time, the assessment of all possible risks of new work. The result of the analysis carried out following the stated principles is the development of an aircraft creation program, considering the financial capabilities of the enterprise, the availability of the necessary scientific and technical reserve, and competent engineering and design staff, as well as the state of production. The latest developments of ANTONOV aviation equipment, created during the years of Ukraine's independence, are presented: the multi-purpose aircraft An-38, the regional passenger aircraft An-140, An-148, An-158, the light transport aircraft An-132D, the medium military transport aircraft of short takeoff and landing An-70. The policy of the enterprise in the social sphere is shown, aimed at ensuring the save of qualified personnel, as well as the training of engineering and technical personnel and workers of aviation specialization. Priority work programs of the enterprise have been identified: airworthiness support, repair, and modernization of ANTONOV aircraft; completion of the program for creating the An-178 aircraft; airworthiness support, repair, and support in the operation of aircraft of ANTONOV Airlines; completion of the import substitution program for materials and components; restoration of serial production and sales of An-148 and An-158 passenger aircraft. The main directions of exploratory research of new projects of competitive aircraft are planned.

Multi-objective optimisation of spare parts allocation and level of repair analysis in performance-based logistics

AbstractIn recent years, Performance Based Logistics (PBL) has been increasingly used to reduce the product lifecycle cost. As a result, the existing logistics analysis methods need to be reassessed due to the difference in PBL from the classical approach. This study considers the Spare Parts Allocation (SPA) and Level of Repair Analysis (LORA), which are the most commonly used problems within PBL, and are the subject of analysis. A comprehensive, multi-objective simulation-optimisation model is developed for a military aircraft operations case study, with the objectives of minimising total cost and maximising total flight hours. The Design of Experiment (DOE) method is used for determining simulation-optimisation parameters. Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method is used for the first time in order to select the best design points. Simulated Annealing (SA) was used for multi-objective optimisation with the SPA model being solved first. Then the LORA problem was added to this model as a decision variable and the effects of the integrated solution (SPA+LORA) were examined. The results show that the integrated solution yields remarkably better results in terms of flight hours and cost when compared to the SPA optimisation approach alone. Moreover, the proposed model provides a profit-centric approach and can be efficiently used as a decision support tool for both customers and suppliers for difficult and complex logistics support activities.