Military Aircraft Research Articles

Military aircraft flight and maintenance planning model considering heterogeneous maintenance tasks

Military aircraft flight and maintenance planning model considering heterogeneous maintenance tasks

Effect of sustainable/durable composite materials on dynamic performance of aircraft shelters.

Aircraft shelter technology has been evolving over years along with the global technological revolution. They first appeared in the 20th century with the main purpose of protecting parked aircraft. Recently, they are considered a globally important topic in the aerospace field, especially for shielding military aircraft. On the other hand, the civil revolution nowadays is extremely unsustainable. The world is facing vital problems due to the massive consumption of non-renewable resources and pollution of the environment and atmosphere. Sustainability development is not an option anymore; it is the only choice to survive. Therefore, there is a demanding need to push the boundaries of sustainability and go through a green revolution by using Eco-friendly materials and searching for alternatives for non-renewable resources. In this study, sustainable composite materials that are probably used as impact shields in aircraft shelters that are cheaper than typical ones were studied. The applicability of utilizing silica fume and steel slag as partial and full replacements for non-renewable resources in the composite mixture was established. Fiberglass and steel meshes were also implemented as reinforcing elements. The performance enhancement of using such materials in composite mixtures was investigated. Results showed that utilizing silica fume and steel slag enhanced the compressive strength of sustainable composite mixtures by about 9.38%. Similarly, superior dynamic performance was achieved by approximately 800% using different reinforcement techniques.

Defense Diplomacy in Peace Time to Strengthening Military Partnership and Enhancing Defense Capabilities between Indonesia and France through the Acquisition of Rafale Jets

Defence diplomacy, also referred to as military diplomacy, involves the peaceful utilization of armed forces to enhance a nation's diplomatic relations and advance its global objectives. This is achieved through various means such as officer exchanges, joint training initiatives, cultural interactions, and reciprocal naval visits, among others. This abstract explores the significance of defense diplomacy during times of peace in strengthening military partnerships and enhancing defense capabilities between Indonesia and France, with a specific focus on the acquisition of Rafale jets. Defense diplomacy serves as a crucial tool for fostering international relations and promoting regional stability. The procurement of advanced military aircraft such as the Rafale jets not only bolsters Indonesia's defense capabilities but also deepens the bilateral defense cooperation between the two nations. This research will use qualitative research methods. This research was conducted using a qualitative descriptive research approach utilizing the literature review method. The literature review was performed by the researcher by utilizing various secondary data sources such as books, journal articles, press releases, news articles, as well as institutional websites. The abstract highlights the benefits of the Rafale jets in terms of their advanced technology, versatility, and interoperability, enabling Indonesia to address various security challenges effectively. Moreover, it emphasizes the positive impact of this strategic acquisition on defense industry collaboration, technology transfer, and human capital development. By strengthening military partnerships and enhancing defense capabilities through the acquisition of Rafale jets, Indonesia and France can pave the way for mutually beneficial and sustainable defense cooperation, contributing to regional security and stability.

Design and Implementation of 12-Bit Arithmetic Logic Unit with 8 Operation Codes to Field Programmable Gate Array

Digital system has been a part of human life since the invention of the computer with a microprocessor as the central brain. At the heart of a processor is an Arithmetic Logic Unit (ALU) that handles arithmetic and logic operations. The need for high-speed computation to handle complex computations demands microprocessors with higher performance. The existing 4-opcode 8-bit ALU cannot handle multiplication operations, so a solution is needed. In this research, while raising the appeal of beginners, a 12-bit ALU with eight operation codes (opcode) was designed and implemented in Xilinx’s Field Programmable Gate Array using a schematic diagram approach through logic gates. The designed and implemented ALU provides addition, subtraction, multiplication, square, AND, OR, NAND, and XOR operations. The multiplication operation was tested by performing the computation to provided datasets to obtain the distance travelled by ten military aircraft based on their maximum speed and air travel duration to ensure its performance. The computation performance comparison with an 8-bit ALU with four opcodes was also done. The computation was done for air travel between 10 to 60 minutes with a 10-minute difference. It was found that the 12-bit ALU with eight opcodes outperformed its contender with computation differences between 130.815 ns and 1,468.214 ns. This high performance is supported by the multiply operation that does repeated addition at one time. Based on this finding, the 8-opcode 12-bit ALU is more efficient in the context of computation time, with consistent accuracy. Moreover, the computation time required to calculate military aircraft data with different maximum speeds and air travel duration is only 119.501 ns.

Effectiveness of water spray in infrared signature suppression of engine plumes

In modern military aircraft, reducing the Infrared (IR) signature is critical for stealth. However, the IR signature from the engine plume is particularly challenging to address due to its link with engine operation and its unique, non-continuous characteristics. In this study, a novel approach using a water spray cloud to attenuate the IR signature from the engine plume was proposed, and it is experimentally verified by employing a micro-turbine engine. Six water nozzles generated the water spray cloud, and IR signature reduction was quantitatively measured using an IR spectrometer. Variations in water injection pressure and observation angles were used as experimental conditions. The results revealed that the IR signature was reduced with higher water injection pressure, attributed to the increased thickness of the water spray cloud. The IR signature from the engine plume was effectively attenuated by the water spray cloud in overall, with a more pronounced effect observed at lower observation angles due to the extended path within the cloud. The potential of water spray clouds for enhancing the IR stealth of military aircraft is underscored by this research.

Bioinspired Artificial Hair Sensors for Flight-by-Feel of Unmanned Aerial Vehicles: A Review

Flight-by-feel is an emerging approach to flight control that uses distributed arrays of pressure, strain, and flow sensors to guide aircraft. Among these, hair-type flow sensors have received the least attention yet hold some advantages over conventional sensors. This paper reviews hair-like flow microsensors developed since 2013, focusing on developments in design, construction, and application. Hair-like flow sensors can be found in artificial cochleae, submersible navigation, terrestrial robots, and, rarely but increasingly, on aircraft. In this survey, we categorize hair-like flow sensors into three types (long whisker-like hairs, ultrasensitive microscale hairs, and short trichoid-like hairs), and primarily cover sensors that may be suitable for use on aircraft. The recent progress in flow-based flight control using distributed sensing is also discussed, along with the optimization of sensor placement and the potential for flight-by-feel in sixth-generation military and civilian aircraft designs. This survey aims to provide a consolidated account of the history and state-of-the-art of artificial hair-cell flow sensors, motivate consideration of flight-by-feel as a viable flight control paradigm, and define avenues for future research. As engineering and biological science continue to converge, we hope that researchers in both fields find this survey an inspirational and useful resource.

Application of a Multidisciplinary Design Process to Assess the Influence of Requirements and Constraints On the Design of Military Engines

Abstract The design of supersonic military aircraft is a complex multidisciplinary optimization (MDO) process in which the dependencies and strong interactions between engine and aircraft must be imperatively considered. Applying a fully coupled propulsion-airframe design system is a highly challenging task, since it requires a set of numerically stable analysis tools capable of optimizing multiple design variables simultaneously. To improve computational efficiency, the application of low-fidelity design of experiment (DOE) methods aid in narrowing down the selection of suitable combinations of design parameters. This approach allows the division of the multidisciplinary process into subsystems, each of which can be served by specialized engineers. Interactions between the disciplines are then considered by exchanging DOE-based sensitivities. This paper presents the multidisciplinary design process developed at the German Aerospace Center (DLR), - in which the airframe and propulsion system are designed simultaneously whilst effectively utilizing DOE-based sensitivities. Guiding the work is an application case on the preliminary design of military engine concepts considering its effects on overall integrated aircraft architecture. The design process is used to investigate the influence of important engine parameters such as overall pressure ratio (OPR), bypass ratio (BPR) and turbine entry temperature (T4) on the design of military aircraft. Furthermore, the impacts of thrust requirements and technological constraints of the engine are analyzed

Correction: A Survey on Structural Coupling Design and Testing of the Flexible Military Aircraft

Correction: A Survey on Structural Coupling Design and Testing of the Flexible Military Aircraft

Extension of methods based on the stabilized finite element formulation for the solution of the Navier–Stokes equations and application to aerodynamic design

Accurate and fast simulation-based processes are key to the design of future aircraft. Computational Fluid Dynamic technology at Dassault Aviation relies on numerical formulations developed by T.J.R. Hughes. Continued efforts over the past years have led to impressive capability and new tools that are applied to the design of both long-range business jets and military aircraft. Recent advances are related to multidisciplinary design technology and to complex flow physics associated to turbulence and transition phenomena. This paper will present a number of examples to illustrate these new capabilities. Methods developed for the flutter analysis of configurations with complex flow features will be discussed. Aerodynamic simulations required for structural fatigue analysis will also be presented. Finally, complex thermodynamics capabilities will be illustrated.

Harmonising and standardising military airworthiness in Europe: a review of key aspects and achievements

AbstractThe distinct operational characteristics of military aircraft, relative to civil aircraft, have impeded the standardisation of airworthiness management practice across Europe. Standardisation has been further deterred by the intertwined certification and qualification activities specific to military aircraft. The management of airworthiness in European military aviation has undergone significant changes over the past 15 years, with the progress made attributed to the harmonisation efforts driven by the European Defence Agency (EDA). The creation of a Military Airworthiness Authorities Forum and the development of the European Military Airworthiness Requirements (EMAR) have been instrumental in creating a more homogenous regulatory landscape. The examples of five main players of the European aerospace sector, namely France, Italy, Germany, Spain and the United Kingdom, are examined from the point of view of adoption and implementation of an EMARs-based system. Their regulatory structures have revealed similarities and primary differences. The EMAR’s framework has enabled a gradual build-up of technical knowhow within the European countries who embraced this, civil-based, framework. All five countries have adopted EMARs, though through a variety of regulatory constructs. Their regulatory structures exhibit diverse practices, especially in how initial and continuing airworthiness is managed. Some countries have also elected to have more than one authority overseeing/been responsible for airworthiness. Closer collaboration between national Military Aviation Authorities (MAAs) can be achieved through standardisation at regulatory structure level. The establishment of a joint MAAs may be the next logical step in the harmonisation process, in line with EDA objective’ for a EU-wide authority with greater powers.

Effects of Synthetic Jets on Swirl Inflow in a Variable-Geometry Twin Air-Intake

Air intakes are an integral part of contemporary passenger and military aircraft engines. Their impact on aerodynamic performance across the entire flight envelope is critical to aircraft flight safety, efficiency, and manoeuvrability, especially at high Mach numbers due to shock waves. The high demand for reductions in aircraft weight and size and enhancements in durability, comfort, and thermal and radar signatures compel researchers and engineers to explore new designs and develop efficient air intakes for high-performance aircraft engines. Although a number of studies on air intake have been conducted and reported in the open literature, there is little information available in the public domain on bifurcated twin air intakes using synthetic jet. As a result, the primary goal of this research is to use computational fluid dynamics modelling to investigate the effects of synthetic jets on swirl inflow variable geometry twin air intake aerodynamic performance over a range of Reynolds numbers. Some important parameters (distortion coefficient, non-uniformity index, swirl coefficient, and static and total pressure coefficients) were investigated. Both static and total pressure recovery have been increased at all swirl numbers. A significant decrease in distortion coefficient and swirl coefficient has also been achieved, reaching a 53% reduction in the distortion coefficient and a 62% reduction in the swirl coefficient. The reduction in the non-uniformity index is achieved by 62% for the controlled flow case. The findings show that synthetic jets are effective in controlling the flow separation in the twin air intakes and enhancing aerodynamic performance.

Experimental Characterization of Supersonic Diamond Jet Acoustics

Acoustic emissions from supersonic jets are of interest due to their deleterious effects on nearby personnel and structures. As development of both military and commercial supersonic aircraft continues to grow, it is essential to combat increasing noise pollution. Axisymmetric jets are highly prevalent where their aeroacoustic characteristics have been well-documented; in contrast, relatively few studies have examined non-axisymmetric jets. In the present study, aeroacoustics of supersonic jets produced by a diamond-shaped Mach 2 nozzle are explored across a large operational envelope under different pressure ratios ranging from highly overexpanded to moderately underexpanded. Measurements of the far-field acoustics in an anechoic environment were used to characterize the acoustic flowfield and contrast the distribution of energy in the spectral domain between the characteristic major and minor axes of the nozzle. Overall, the diamond jet exhibits a highly directional acoustic field with a distinct local minimum for sideline noise. Furthermore, screech behavior was only observed in a narrow, overexpanded flow regime; this is in contrast to the documented behavior of axisymmetric and rectangular jets. Over the conditions examined there is no indication of distinct staging. Additionally, there exists a nozzle pressure ratio threshold beyond which peak noise switches axes.

A Comparison of the Damage Tolerance of AA7075-T6, AA2024-T3, and Boeing Space, Intelligence, and Weapons Systems AM-Built LPBF Scalmalloy

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.

Statistical Algorithms with Phase-Sensitive Detection for the Number of Hovers and S Turns in Aircraft Flights

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.

Rolls-Royce - 100 Years of Power

The date of December 17th 2003 is well recognised as the centenary of the first powered flight. What is less well known is that May 4th 2004 also represented another historical centenary for aerospace. On this date in 1904, the Charles Rolls and Henry Royce first met and their drive and ambition led to the formation of this world famous company. Since that day, Rolls-Royce has established itself with a reputation for excellence and innovation across a wide range of engineering products. This presentation will explore the evolution of aero-engine development at Rolls-Royce. The story starts with the highly successful Eagle and Falcon, which dominated the Allied propulsion systems of World War I. This success was followed with the Merlin, arguably the most recognised name in aerospace engines in the 1940s, before Frank Whittle’s pioneering work led to the development of the modern jet engine. Rolls-Royce is also the world leader for the unique propulsion technologies required for both supersonic and V/STOL flight and this presentation will describe design and development of these engines. The Olympus engine, which has accrued almost one million engine flying hours on Concorde and over one billion supersonic engine miles. Rolls-Royce V/STOL experience on the innovative Pegasus engine in the Harrier has also secured a position on the LiftSystemTM, the STOVL propulsion system for the Joint Strike Fighter. Today Rolls-Royce is a world leader in gas turbine technology for civil and defence aerospace, marine and energy power systems. This presentation will describe the process of developing technology once, and using it many times which has led to the development of a broad range of the latest gas turbine engines and technologies, including EJ200, F136, Adour and RTM322 for the latest military combat, trainer and helicopter aircraft. The next 100 years in gas turbine technology is certainly going to be as challenging, new and exciting as the past century. We can expect the growth of UAVs requiring More Electric, Variable Cycle and High Mach engines as well as a wealth of unique, new propulsion systems. With over 100 years success and innovation in the aerospace power business, Rolls-Royce is ideally placed to face these challenges

The Terprom® Digital Terrain System (DTS)

Developed specifically for tactical military aircraft operations, TERPROM® is the world leading Digital Terrain System, offering a range of capabilities that can provide both safety and tactical benefits to the aircraft. The system is an established and well-proven product that has been in production since 1991. To date it has been selected by fourteen Nations worldwide for use on numerous platforms. The number of military aircraft equipped with TERPROM® is now over 5000 and growing. TERPROM® provides the following functions: Terrain Referenced Navigation (TRN), Predictive Ground Collision Avoidance System (PGCAS), Advanced Terrain Avoidance Cueing (ATAC), Obstruction and Wires Warning and Cueing (OWWC), Database Terrain Following (DBTF), Air to Ground Ranging Functions, Terrain Awareness Display (TAD). At the core of the system is the Terrain Referenced Navigation (TRN) capability which navigates by combining aircraft navigation data (e.g. inertial and, or GPS) and radar altimeter measurements of height above ground level (AGI), with terrain heights alms from the stored map data, to produce a navigation solution referenced to the terrain map data. This navigation solution then allows the other TERPROM® functions to use the map data to provide their safety and tactical capabilities. Three variants of TERPROM® have been developed to satisfy the airborne platform market: - Fast Jet, Military Transport, Helicopter. TERPROM® is a living product that has and continues to receive significant internal investment to increase its capability, functionality and performance to support future opportunities. Current areas of development include: Use of higher resolution map data which will increase the performance of TERPROM® and offer enhanced capability to platforms flying nap of the earth, enhanced capability in urban areas and could also reduce any platform reliance on GPS. Integration with active forward looking sensors to provide additional information to the Navigation, Situational Awareness and Ranging functions and also to provide new capabilities such as real time mapping of unmapped terrain features and obstructions.

Composites for Reinforcement of Damaged Metallic Aircraft Wings

Advanced composites, because of their inherent directional properties and ability to take complex contours are ideally suitable for repairs even in aged metallic aircraft structures. The composite materials can be suitably tailored to suit the strength and stiffness requirement at location of the damage on the parent structure. The laminate patch can be bonded to the structure. This avoids the use of large number of fasteners that are required for repair with metallic repair patch. A composite patch repair has been carried out on a military aircraft wing. The skin and the spar flange near the landing gear part were cut in order to gain access to a loosened bolt. With a request from HAL (Nasik), National Aerospace Laboratories (NAL) has taken the responsibility of designing and realizing composite repair at the damaged locations. The geometry and lay-up of the patches have been arrived at based on the strength requirements. The patches were fabricated at NAL and the repair was implemented on the aircraft. The quality of the patch bonding was checked using non-destructive testing (NDT). The aircraft has completed about 130 hrs flying with the repair. The repair was certified by the regulating authority and has been recommended to be implemented on other twenty aircraft also. This task has been completed successfully and all the aircraft are flying. This is an important achievement both for NAL and HAL (Nasik). This paper discusses the repair design, patch fabrication and implementation of the repair.

A Survey on Structural Coupling Design and Testing of the Flexible Military Aircraft

A Survey on Structural Coupling Design and Testing of the Flexible Military Aircraft

Composite Airframes-Opportunities, Options and Issues

Worldwide, both in the Civil and Military Aircraft Industry, there is an increasing usage ofcomposites due to the inherent advantages they offer. However, even today, the total potentialof composites has not been realized as the designers are still conservative. Also, cost hasbecome a very important factor especially for civil aircraft. In order to realize the full potentialof these materials, extensive research is being conducted in several areas that include design,newer, faster and cost effective approaches to manufacturing, better understanding of damagetolerance and associated failure theories, crashworthiness behavior and the like. StructuralHealth monitoring has progressed significantly and could play a major role in the reductionof maintenance costs and prevention of catastrophic failures. This paper makes an effort toaddress the options, challenges and issues that are confronting the composite industry today.

The First Sub-machine Gun: The Officine di Villar Perosa Machine Gun of 1915 (Part I)

This article aims to present a detailed and more nuanced examination of the development, production, and military application of the Pistola Mitragliatrice OVP (‘OVP Machine Pistol’), a unique and unusual twin-barrelled, pistol-calibre machine gun introduced in Italy during the First World War. The design process which led to the OVP machine gun is first described, followed by an assessment of its rapid adoption by the Italian Army and subsequent deployment as both an infantry support weapon and an aerial weapon fitted to military aircraft. Its efficacy in combat and impact on infantry tactics of the period are reviewed, in addition to its influence on the design of similar Austro-Hungarian small arms, and finally, its evolution into both a single-barrelled automatic carbine and a rifle-calibre light machine gun are described, along with its post-war legacy.