Generation Fighter Research Articles

Skyward Bound: The HAL Odyssey - Innovations, Alliances, and Trials

Hindustan Aeronautics Limited (HAL) is a cornerstone of India's aerospace and defence sector, significantly influencing the industry landscape since its inception. Established in 1940, HAL has evolved from manufacturing foreign aircraft to developing indigenous technologies, including the Light Combat Aircraft (LCA) Tejas and the Advanced Light Helicopter (ALH) Dhruv. The organization has faced numerous challenges, such as quality control issues, bureaucratic hurdles, and the need for effective marketing strategies, impacting its operational efficiency and reputation. Nevertheless, HAL's commitment to innovation, skill development, and strategic collaborations with small and medium enterprises (SMEs) has fostered a robust aerospace ecosystem in Bangalore. As HAL continues to expand its portfolio, including projects like the Fifth Generation Fighter Aircraft (FGFA) and the Multirole Transport Aircraft (MTA), it remains a pivotal player in enhancing India's defence capabilities and positioning the nation as a formidable force in the global aerospace arena.

Effects of training flights of combat jet pilots on parameters of airway function, diffusing capacity and systemic oxidative stress, and their association with flight parameters

BackgroundFighter aircraft pilots are regularly exposed to physiological challenges from high acceleration (Gz) forces, as well as increased breathing pressure and oxygen supply in the support systems. We studied whether effects on the lung and systemic oxidative stress were detectable after real training flights comprising of a wide variety of exposure conditions, and their combinations.MethodsThirty-five pilots of the German Air Force performed 145 flights with the Eurofighter Typhoon. Prior to and after flight lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), alveolar volume (VA), and diffusing capacities per volume (KCO, KNO) were assessed. In addition, the fractional concentration of exhaled nitric oxide (FeNO) was determined, and urine samples for the analysis of molecular species related to 8-hydroxy-2’-deoxyguanosine (8-OHdG) were taken. For statistical analysis, mixed ANOVA models were used.ResultsDLNO, DLCO, KNO, KCO and VA were reduced (p < 0.001) after flights, mean ± SD changes being 2.9 ± 5.0, 3.2 ± 5.2, 1.5 ± 3.7, 1.9 ± 3.7 and 1.4 ± 3.1%, respectively, while FeNO decreased by 11.1% and the ratio of 8-OHdG to creatinine increased by 15.7 ± 37.8%. The reductions of DLNO (DLCO) were smaller (p < 0.001) than those of KNO (KCO). In repeated flights on different days, baseline values were restored. Amongst various flight parameters comprising Gz-forces and/or being indicative of positive pressure breathing and oxygenation support, the combination of long flight duration and high altitude appeared to be linked to greater changes in DLNO and DLCO.ConclusionsThe pattern of reductions in diffusing capacities suggests effects arising from atelectasis and increased diffusion barrier, without changes in capillary blood volume. The decrease in exhaled endogenous NO suggests bronchial mucosal irritation and/or local oxidative stress, and the increase in urinary oxidized guanosine species suggests systemic oxidative stress. Although changes were small and not clinically relevant, their presence demonstrated physiological effects of real training flights in a modern 4th generation fighter jet.

Fluid and aero-acoustic analysis of internal bays: Geometric length-to-depth effects

Weapon bays are essential for any bomber, Next Generation Fighter Aircraft, and unmanned combat air vehicles (UCAVs). As flow approaches the leading edge of such cavity, it separates and forms a shear layer. The structure of bays and residing stores thus become prone to intense acoustic and aerodynamic loading– a major design concern. Cavity flow shows significant dependence on its shape. This makes flow actuation possible by only changing the geometric variable of length-to-depth (L/D) ratio. This study compares two bays with an L/D ratio of 5 (deep) and 10 (shallow) in terms of acoustics and affiliated aerodynamic drag. A transient RANS formulation obtained overall sound pressure levels (OASPL) on bay ceilings. An integral-based method was also used to predict far-field noise propagation due to flow fields of both cavities. It is argued that at Mach 0.6, the character of bays changes remarkably when its L/D is altered. Deeper bays show a smoother pressure profile and significantly less drag while operating in shear mode. Shallow bays, on the other hand, show bluff body type drag with uneven pressure distribution, having the potential of causing downwash on residing stores. At the same time, acoustic loads on the ceiling and acoustic signatures in the far-field are comparable for both cavities.

Weapon of choice: a neoliberal institutional perspective on Italy’s decision to procure a sixth generation fighter aircraft

ABSTRACT In 2018, Italy decided to join the British-led Team Tempest to develop a sixth generation fighter aircraft. This decision came at the expense of a rival project, the Future Combat Air System (FCAS), led by France and Germany. The Italian decision to join Tempest raises a theoretical question overlooked by the existing literature: when states have different cooperative procurement options, what makes them choose one rather than another? The aim of the article is to provide an analytically informed account of the process that led Italy to join Tempest. In doing so, we adopt a neo-institutionalist perspective, as it allows us to identify the actors and motivations that made this outcome possible. We argue that due to the peculiar Italian bureaucratic-institutional setting, no domestic actor was solely responsible for the final decision. The final decision to join Tempest was the result of a coalition between the Armed Forces and defence firms.

Aerospace Technologies: A Walk Through and Dreams Ahead

This paper deals with the highlights of the progress made within the country and in particular by Aeronautical Development Agency (ADA) n the various fields of the fighter aircraft technologies and the road map ahead. Many technologies have been developed successfully and incorporated in making of Light Combat Aircraft (LCA). The recent technology developments in the field of aeronautics have made the new generation fighter aircrafts more efficient, lethal and combat effective. India also needs to keep its pace with advancing technology. It requires enormous amount of effort from the scientific and engineering community in India to keep the pace with advancing technology. In this perspective, ADA in collaboration with DRDO and other organizations has initiated R&amp;D activities for the development of these demanding technologies required in the future fighter aircrafts. This paper discusses some of the important technologies already developed and incorporated in LCA and some other ongoing technology developments. Finally it deals with the identification of future technologies essential for future aircrafts and efforts being put in by ADA in realizing these technologies in a foreseeable future.

A review of the fighter airfoils from first-generation to fifth-generation

In the field of air control, fighter has always played a vital role. Airfoil, as an indispensable part of fighter, has always been attached importance to research and development. Since the 1940s, the airfoil shape has undergone many significant changes, and the technical level has gradually realized from subsonic to transonic and then to supersonic. This paper mainly analyzes and summarizes the design characteristics and changing trends of the airfoils by analyzing the aerodynamic shapes of the first to fifth generation fighter airfoils. The performance that the airfoil needs to meet gradually improves over time. In the new era, the demand for airfoil design is more diversified. Countries pay attention to improving the aerodynamic performance, stealth performance, mechanical stress structure, material technology and morphing technology of airfoils. To meet the development needs of the new generation of fighter, this paper proposes that it is necessary to improve the level of stealth technology and morphing technology of fighters, and at the same time, improving of the CFD and the Navier-Stokes equations matter a lot. Whats more, the comprehensive application of multidisciplinary technology may make the future fighter more information and intelligent.

Pretreatment of aircraft carbon fiber-reinforced plastic skin by plastic abrasive jet machining

In this study, a new pretreatment method was proposed for efficient nondestructive substrate pretreatment of carbon fiber-reinforced plastic (CFRP) skin stealth coatings for 4th and 5th generation fighter jets, which can effectively replace hand sanding and meet the requirements of high efficiency and damage prevention of the substrate. Erosion experiments were carried out on a commercial sandblasting cabinet by the Taguchi method for CFRP skin pretreatment. The mechanisms of hand sanding and plastic abrasive jet machining (PAJM) were introduced in detail. The advantages of PAJM over hand sanding for CFRP skin pretreatment were investigated in terms of surface morphology, wettability, and adhesion, in order to achieve the objective of enhancing coating adhesion and prolonging the service life of the substrate. These results show that the damage of PAJM-eroded surfaces is lower than that of hand-sanded surfaces, and safe process parameters for no fiber damage are provided. The critical pressure of carbon fiber damage was likely to be 0.4 MPa or lower, and the adhesion of primer could reach 3.6 MPa. This study provides significant guidance for the pretreatment of new-generation aircraft CFRP skin. Highlights The erosion mechanism of plastic abrasive is semi-ductile erosion. Compared with manual sanding, PAJM is more suitable for carbon fiber-reinforced plastic (CFRP) substrates pretreatment. The proper PAJM process can realize the non-destructive CFRP substrate. Obtained the best pretreatment process

Advanced multi-input system identification for next generation aircraft loads monitoring using linear regression, neural networks and deep learning

Over the past decade, the ideologies surrounding Structural Health Monitoring (SHM) have shifted drastically within the aerospace engineering disciplines, predominantly onus to rapid advancements in machine intelligence. While traditional SHM practices are based on scheduled and pre-emptive maintenance, the NextGen SHM system, known commonly as Prognostics and Health Management (PHM), has a focus on pro-active condition-based maintenance, forecasting and prognostics — a milestone on the trajectory towards Digital Twin technology. In aircraft, particularly defense fighter air platforms, fatigue-critical high-amplitude cyclic behavior is unavoidable, where rapid fatigue life consumption due to an airframe buffet is one of the most problematic phenomena that engineers have encountered throughout the 4th and 5th generation fighter programs. This paper serves as a point-of-reference consolidating a range of machine learning models, under a single benchmark aircraft Multi-Input Single-Output (MISO) loads monitoring problem. Linear regression models, traditional (shallow) artificial neural networks, and deep learning strategies are all explored, where strain sensors are used as inputs to predict representative bending and torsional dynamic (buffet) and quasi-static (maneuver) load spectra on an aircraft wing during transonic buffeting maneuvers. For the benchmark system considered herein, the MISO coherence ranges from high to very weak depending on the load case, hereby providing a unique opportunity to rigorously explore the time-series modeling requirements and make valuable recommendations across a wide range of data-qualities that are likely to be encountered in traditional or modern aircraft data-acquisition systems or, for that matter, in any mechanical systems plagued by fatigue.

Radio-electronic control systems of sixth generation fighters. Part 2. Architecture of the onboard complex. Features of integration and element base

Radio-electronic control systems of sixth generation fighters. Part 2. Architecture of the onboard complex. Features of integration and element base

Radio-electronic control systems of sixth generation fighters. Part 1. Approaches to development. Optimization problems

Radio-electronic control systems of sixth generation fighters. Part 1. Approaches to development. Optimization problems

Radio-electronic control systems of sixth generation fighters. Part 3. Hierarchical levels of information processing and control formation. Directions of development

Radio-electronic control systems of sixth generation fighters. Part 3. Hierarchical levels of information processing and control formation. Directions of development

Analysis of the stability of automatic tracking of super maneuvering air objects by radio technical tracking systems of the multichannel radar

Multichannel tracking radars with phased antenna arrays are widely used to track air targets. The use of a phased array in combination with digital computing technology allows to control the radar radiation pattern and track several targets in the time distribution mode. Air target tracking in a multichannel radar is provided by subsystems for measuring range, radial velocity and angular coordinates, in most cases, without adaptation to the external influence characteristics. When tracking supermaneuverable air targets, such as 5th and so-called 4++ generation fighters, there is a decrease in the accuracy and stability of tracking relative to the area without maneuver. If the tracking system algorithms are tuned to a low intensity of maneuvering or its absence, a significant increase in the error of tracking the aircraft in the maneuvering section will lead to disruption of auto tracking due to a significant dynamic component of the error. The stability of auto-tracking of maneuvering targets by subsystems of range, radial velocity, and angular coordinates with fixed parameters for the case when the setting of the parameters of the tracking system algorithms coincide with the characteristics of the external influence is analyzes in the paper. The influence of the observation model parameters, the stochastic model of the target movement with exponentially correlated values of the target acceleration, and the measurement period of the target coordinates on the potential tracking accuracy by radio technical tracking systems of the multichannel radar is investigated. To assess the stability of auto-tracking, it is proposed to use the equivalent aperture size of the discriminating characteristic. The influence of the parameters of the target movement stochastic model, the observation model, and the measurement period of the target coordinates on the stability of auto-tracking in terms of range, radial velocity, and angular coordinates is estimated. It is shown that the "weak link" is the radial velocity tracking system. As a result of the research carried out, it becomes possible to further assess the feasibility of adapting the auto-tracking systems to the target maneuvering characteristics and to develop recommendations for choosing the measurement period of the target coordinates.

A fault-tolerant control method for distributed flight control system facing wing damage

With the strong battlefield application environment of the next generation fighter, based on the design of distributed vehicle management system, a fault diagnosis and fault-tolerant control (FTC) method for wing surface damage is proposed in this paper. Aiming at three kinds of wing damage modes, this paper proposes a diagnosis method based on the fault decision tree and forms a fault decision tree for wing damage from the aspects of sample database construction, feature parameter extraction, and fault decision tree construction. Based on the fault diagnosis results, the longitudinal control law based on dynamic inverse and the lateral-directional robust control laws based on linear quadratic regulator (LQR) are proposed. From the simulation examples, the fault diagnosis algorithm based on the decision tree can complete the judgment of three wing surface damage modes within 2 ms, and the FTC law can make the fighter quickly return to a stable flight state after a short transient of 1 s, which achieves the fault-tolerant goal.

'A Sixth Generation Fighter?' An Update

Abstract: This working paper endeavors, with an eye to the author's prior discussion of the sixth generation fighter aircraft (initially drafted in 2010), consider the development of the technology in the past decade as revealed through the publicly available literature on the subject, and that development's interaction with the technological, economic and political changes of the period. It concludes that while (as the author had suggested would be the case) technological change has been slower than predicted, and economic growth slow, making implausible the development and large-scale procurement of the radical aircraft in question (morphing, hypersonic, intercontinental-range, potentially unmanned fighter aircraft with integral directed-energy weaponry), the more aggressive relations among the major powers have seen them more determined to acquire the most advanced combat aircraft available. The result is the presently aggressive pursuit of new fighter designs of more advanced but less revolutionary character (which, if characterized as sixth generation fighters, may ultimately prove to be fifth generation or fifth generation+ planes).

DEVELOPMENT STRATEGIC OF SIMULATOR TECHNOLOGY 4.5 GENERATION FIGHTER AIRCRAFT FOR SUPPORTING NATIONAL DEFENSE SYSTEM

&lt;div&gt;&lt;p class="Els-history-head"&gt;The fighter aircraft project is one of the defense and security equipment (alpalhankam or alat peralatan pertahanan dan keamanan) priority programs contained in the defense industry roadmap. Indonesia and South Korea undertook a joint development program in developing 4.5 generation fighter aircraft. However, Indonesia experiences several obstacles in the development of fighter aircraft, one of which is the ability of disparity and mastery of fighter technology. One of the critical components used as one of the development programs is simulator technology development. Mastery of simulator technology can improve the ability of Technology Readiness Level (TRL) from technology development fighter aircraft and can cause multiplier effects in other fields. Therefore we need a development strategy that is appropriate for the development of simulator technology. This study aims to analyze and define the benchmark level of performance or from the critical components which will then be used as a reference for the development strategy of the 4.5 generation fighter simulator for joint development projects. The method used in this study is a mixed-method with an approach system engineering uses quality function deployment tools and Critical Technology Element (CTE) technology assessment to identify which CTE then used as a reference strategy for the development of fighter simulator technology. The results of the study show that there are several CTE values along with simulator technology performance scores, among others mission 92.5%, data 83.56%, motion 52.51%, and strategic options that can be used in the technological development of fighter simulator generation 4.5 such as strategic joint development, self-development, and local content/offset.&lt;/p&gt;&lt;/div&gt;&lt;div&gt; &lt;/div&gt;

Windblast testing of an aircrew helmet: An approach to neck load analysis

Introduction: Modern generation fighter aircraft has expanded the escape envelope for a fighter aircrew. With the ejection occurring at very high airspeeds, windblast is a cause of major injuries and fatalities. Flying helmet, before its induction into operational usage, must be tested in simulated windblast conditions to ensure that they provide adequate safety. Material and Methods: Windblast tests were conducted on a newly designed/procured helmet in a standard windblast test facility as per Mil Std MIL-V-29591/1. A large instrumented Hybrid III male dummy was used for the tests. The test conditions were: Wind speed 600 ± 60 KEAS, rise time of 125 ± 20 ms, time at peak wind velocity of 300 ± 50 ms, and total exposure time of ≥3 s. Structural integrity, retention with the headform, and recorded neck loads were assessed for interpretation of test results. Results: Helmets could withstand the windblast conditions without any significant structural failures and were retained with the headform during the entire duration of test conditions. However, analysis of the neck loads resulted in a significant dilemma in aeromedical decision-making, there being no laid down criteria in the Mil Specification. The neck tension forces were more than the acceptable limits and found to have the potential for significant neck injuries as per the Injury Assessment Reference Values specified in AGARD-AR-330 specifically in the tests where blast was head on and outer visor in up configuration; however, these values were within the acceptable limits as per the other proposed criteria. Similarly, analysis of the neck tension extension combined effects revealed conflicting outcomes for Nij performance limits specified in various standards. This paper discusses the critical analysis of neck loads vis-à-vis the neck injury criteria to understand the neck loads generated during windblast conditions and its implication on aircrew safety. Conclusion: Neck loads assessment is critical in predicting aircrew safety during windblast testing. In the absence of a clearly defined criteria in the Mil Specification, critical ananlysis of neck loads vis-à-vis recommended standards in scientific literature be done to make meaningful conclusion.

Engine weight estimation of fifth generation fighter aircraft for high range and manoeuvrability

This study focuses on afterburner turbofan engine weight estimation for fifth generation fighter aircrafts. Model developed in this study by investigating 26 engine cases categorised by the criteria the requirement of selection amongst to engines expected to be used in fifth generation fighter depend on four parameters with ≈ ±25% error. Technology level effect engine weight strongly so parameter reflect technology level is determined based on new technology engines used in fifth generation fighter aircraft by statistical method. Model reflect technology level is expected to be used in conceptual design stages of fifth generation fighter engine.

Engine weight estimation of fifth generation fighter aircraft for high range and manoeuvrability

Engine weight estimation of fifth generation fighter aircraft for high range and manoeuvrability

The Analysis of Jet Fighter Generations of the 2nd Half of the 20th Century and Its Significance for the History of Aviation

This paper attempts to explore the history of the development of a minor segment of aircrafts, fighters equipped with jet engines, by analyzing the numbers of these aircrafts belonging to different generations, and to assess the relevance of this approach for the history of aviation. Based on the open printed sources and materials from the Internet, a database was compiled on the numbers of the first to fourth generation fighters in 1945–1999. The dynamics of the development of the world’s fleet of fighters is provided; the reasons behind some of its features are explained, and it is revealed how this dynamics correlate with the 20 th century events. The analysis of this work’s results allows to conclude that this approach can be effectively used in the studies on the history of aviation.

A Post-Training Study on the Budgeting Criteria Set and Priority for MALE UAS Design

A recent study proposed a systematic “(budgeting) knowledge discovery educational framework” (BKDEF). This BKDEF is focused on guiding staff training courses for enhancing the ability to allocate the “large but limited” budget for single, high-cost product design. However, except for its initial application to support the budget planning for the next generation fighter design, the framework’s effectiveness is still awaiting further scrutiny. This study fills the gap by providing the “second application” of BKDEF, which is to support another similar decision for designing the medium-altitude long-endurance unmanned aerial system (MALE UAS). This paper verified the effectiveness of the framework through an empirical application and obtained the knowledge required to allocate a budget for MALE UAS design following the group-opinion basis. In addition, the original analytical style for the last “decision analysis” phase of BKDEF, which included pure quantitative analytical items in order to understand the similarities and diversities in the individual opinions, was replaced by a comparative study to discover the homogeneity and heterogeneity between the two budgeting decisions in a larger scope. As a consequence, the two criteria sets did not overlap despite both decisions being related to military aircraft design. The absolute weights for the MALE UAS design criteria were more balanced than those for the air-superior fighter design, even if the size of the criteria set was larger. The results pave a way for future studies on how other military aircrafts are designed, as more confidence about the use of a BKDEF can be gained from increasing applications, thus more insightful aerospace knowledge can be exploited in comparisons with these works.