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Abstract This research was initiated with the goal of developing a significantly stronger aircraft transparency design that would reduce transparency failures from bird strikes. The objective of this research is to demonstrate the fact that incorporating high-strength tempered glass into cockpit window constructions for commercial aircraft can produce enhanced safety protection from bird strikes and weight savings. Thermal glass tempering technology was developed that advances the state of the art for high-strength tempered glass, producing 28 to 36% higher tempered strength. As part of this research, glass probability of failure prediction methodology was introduced for determining the performance of transparencies from simulated bird impact loading. Data used in the failure calculation include the total performance strength of highly tempered glass derived from the basic strength of the glass, the temper level, the time duration of the load, and the area under load.

Abstract Nylon polymer with an optimal blend of Kevlar, fiberglass, and high-speed, high temperature (HSHT) Fiberglass offers improved characteristics such as flexural strength, wear resistance, electrical insulation, shock absorption, and a low friction coefficient. For this reason, the polymer composite manufactured by combining HSHT, Kevlar, and fiberglass with nylon as base material will expand the uses of nylon in the aerospace, automotive, and other industrial applications related to ergonomic tools, assembly trays, and so forth. The proposed work was carried out to investigate the continuous fiber reinforcement (CFR) in nylon polymer using a dual extrusion system. Twenty experimental runs were designed using a face-centered central composite design (FCCD) approach to analyze the influence of significant factors such as reinforcement material, infill pattern, and fiber angle on the fabricated specimen as per American Society for Testing Materials (ASTM) standards.

Abstract With the recent advancement in technologies, researchers worldwide have a growing interest in unmanned aerial vehicles (UAVs). The last few years have been significant in terms of its global awareness, adoption, and applications across industries. In UAV-aided wireless networks, there are some limitations in terms of power consumption, data computation, data processing, endurance, and security. So, the idea of UAVs and Edge or Fog computing together deals with the limitations and provides intelligence at the network’s edge, which makes it more valuable to use in emergency applications. Fog computing distributes data in a decentralized way and blockchain also works on the principle of decentralization. Blockchain, as a decentralized database, uses cryptographic methods including hash functions and public key encryption to secure the user information. It is a prominent solution to secure the user’s information in blocks and maintain privacy.

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Abstract For spacecraft with high power consumption, it is reasonable to build the thermal control system based on a two-phase mechanically pumped loop. The heat-controlled accumulator is a key element of the two-phase mechanically pumped loop, which allows for the control of pressure in the loop and maintains the required level of coolant boiling temperature or cavitation margin at the pump inlet. There can be two critical modes of loop operation where the ability to control pressure will be lost. The first critical mode occurs when the accumulator fills with liquid at high heat loads. The second critical mode occurs when the accumulator is at low heat loads and partial loss of coolant, for example, due to the leak caused by micrometeorite breakdown. Both modes are caused by insufficient accumulator volume or working fluid charge.

Abstract Emissions and effects of climate change have prompted study into fuels that reduce global dependence on traditional fuels. This study seeks to investigate engine performance, thermochemical properties, emissions, and perform NVH analysis of Jet-A and S8 using a single-stage turbojet engine at three engine speeds. Experimental Jet-A results were used to validate a CFX simulation of the engine. Engine performance was quantified using thermocouples, pressure sensors, tachometers, flow meters, and load cells fitted to the engine. Emissions results were collected using an MKS Multigas Emissions Analyzer that examined CO, CO₂, H₂O, NOx, and THC. NVH analysis was conducted using a multifield, free-field microphone, and triaxial accelerometer. This study found that Jet-A operates at higher temperatures and pressures than S8, and S8 requires higher fuel flow rates than Jet-A, leading to poorer efficiency and thrust. S8 produced stronger vibrations over 5 kHz compared to Jet-A.

Abstract The use of converging-diverging (C-D) variable area nozzle (VAN) in military aeroengines is now common, as it can give optimal expansion and control over engine back pressure, for a wide range of engine operations. At higher main combustion temperatures (desired for supercruise), an increase in the nozzle expansion ratio is needed for optimum performance. But changes in the nozzle throat and exit areas affect the visibility of engine hot parts as the diverging section of the nozzle is visible for a full range of view angle from the rear aspect. The solid angle subtended by engine hot parts varies with change in visibility, which affects the aircraft infrared (IR) signature from the rear aspect. This study compares the performances of fixed and variable area nozzles (FAN and VAN) in terms of engine thrust and IR signature of the engine exhaust system in the boresight for the same increase in combustion temperature.

Abstract At hypersonic speed, severe aerodynamic heating is observed, and temperatures are too high to cool by radiation cooling; active cooling such as ablative cooling is helpful in this situation. The Thermal Protection System (TPS) consists of a layer of an ablative material, followed by an insulating material to lower the temperature at the inside wall of the lifting body. The surface area (considering the inside volume of the vehicle constant) of the TPS plays a vital role in heat transfer to the vehicle and heat transferred through the vehicle body. The minimum area sweepback angle (ΛArea-min) is the function of the principal radius (R) and the ratio of the principal radii of the forward bi-curvature stagnation surface (R/r). The ΛArea-min = 80° is obtained for R = 2 m and R/r = 2. The aerothermal analysis of the lifting body is of fundamental interest while designing the TPS.

Abstract Laminated composites are extensively used in the aerospace industry. However, structures made from laminated composites are highly susceptible to delamination failures. It is therefore imperative to consider a structure tolerance to delamination during design and operation. Hybrid composites with laminas containing different fibers were used earlier in laminates to achieve certain benefits in strength, stiffness, and buckling. However, the concept of mixing laminas with different fibers was not explored by researchers to enhance delamination tolerance levels. This article examines the above aspect of hybridization by employing machine learning algorithms and proposes a reliable method of analysis to study delamination, which is crucial to ensure the safety of airframe composite panels.

Abstract Water droplet size variation has been established in the literature as an important variable that influences the behavior and characteristics of water in fuel emulsion. However, with the growing demand for sustainable aviation fuels (SAF), no data is available that shows how these fuels will affect the size of dispersed water droplets and their frequency distribution. To address this lack of knowledge, this study explores and presents experimental results on the characterization of dispersed water droplets in alternative fuels and Jet A-1 fuel under dynamic conditions. The alternative fuels comprised of two fully synthetic fuels, two fuels synthesized from bio-derived materials, and one bio-derived fuel. The data and statistics presented reveal that water droplet frequency and size distribution are sensitive to changes in fuel composition.

Abstract At supersonic aircraft speeds, aerodynamically heated surfaces, e.g., nose, wing leading edges, are infrared (IR) signature sources from the tactically crucial frontal aspect. This study numerically predicts and then illustrates the minimization of IR contrast between the nose and background sky radiance by the emissivity optimization (εw,opt) technique, which has the least performance penalties. The IR contrast between the aircraft nose and its replaced background in 1.9-2.9 μm short-wave IR (SW-IR), 3-5 μm medium-wave IR (MW-IR), and 8-12 μm long-wave IR (LW-IR) bands are obtained. The IR contrast especially in LW-IR (i) increases with flight Mach number (M ∞) for a given flight altitude (H) and εw (ii) decreases with increasing H for a given M ∞ and εw. The εw,opt for a flight altitude of 5 km is found to decrease from 0.99 at M ∞ = 0.001 (low subsonic) in all three bands to 2 × 10−4 in MW-IR and 0.0213 in LW-IR bands at M ∞ = 3 (high supersonic).

Abstract An aeroengine exhaust plume is one of the important sources of infrared (IR) signature in the 3-5 μm and the 2-3 μm bands. Analysis, characterization, and modeling of the exhaust plume IR emission are needed for insight into its role in aircraft survivability against IR-guided missiles. The IR signature estimation of aeroengine exhaust needs estimation of radiative properties of absorbing-emitting exhaust gases, e.g., carbon dioxide (CO2) and water vapor (H2O). The radiative properties of the gases can be estimated by a mathematical model with a spectroscopic database of these gases. Low-Resolution Transmission (LOWTRAN), Moderate-Resolution Transmission (MODTRAN), High-Resolution Transmission (HITRAN), and High-Temperature Transmission (HITEMP) are some commonly used spectroscopic databases. This study compares Statistical Narrowband (SNB) models with the various other mathematical models used for the estimation of radiative properties of exhaust gases.

Abstract The increase in worldwide awareness of environmental issues has necessitated the air transport industry to drastically reduce carbon dioxide emissions. To meet this goal, one solution is the electrification of aircraft propulsion systems. In particular, single-aisle aircraft with partial turboelectric propulsion with approximately 150 passenger seats in the 2030s are the focus. To develop a single-aisle aircraft with partial turboelectric propulsion, an air-cooled interior permanent magnet (IPM) motor with an output of 2 MW is desired. In this article, mathematical system equations that describe heat transfer inside the target air-cooled IPM motor are formulated, and their mathematical analytical solutions are obtained.

Abstract During aircraft wing assembly, machined fiberglass shims are often used between mating parts to compensate for inherent geometric variability due to manufacturing. At present, fiberglass shims for large aerospace structures, such as shims attached to wing ribs, are manufactured either manually or by precision machining, both of which pose a challenge due to tight tolerance requirements and wide geometric variations in the aircraft structures. Relative to articulated arm industrial robots, gantry-style computer numerical control (CNC) machines are costly, consume large footprints, and are inflexible in the application. Therefore, industrial robots are viewed as potential candidates to replace these gantry systems to facilitate metrology, shim machining, and permanent joining of aircraft structure, with all these processes taking place in the assembly process step.

Abstract We demonstrate a virtual proof-of-concept design and experiment for harvesting energy enabling economic and environment-friendly aircraft by recycling forces for power conversion. The harvesting uses piezoelectric materials for extracting energy from the impact at the touchdown during the landing of an aircraft and direct current (DC) generators powered by the rotational motion of the aircraft wheels during taxiing. The design begins with a multidomain model comprising multibody dynamics, mathematical descriptions, abstract behavioral blocks, and programmed code. Piezoelectric harvesting explores six types of materials consisting of ring and disk pad geometries. Both geometries are typical configurations in suspension systems. Recent advances have shown the potential of getting higher voltage out of new materials properties. Our objective is to determine the useful impact force during a touchdown on the pads and a pad type that maximizes the power transfer.

Abstract Passengers would always like to reach their destinations with minimum commute time. Generating a higher thrust is a necessity. This implies that the turbomachinery associated with the power plant has to rotate faster and with higher efficiencies. However, high rotational speeds, mainly in the transonic regime, often lead to boundary layer separation, shocks, compressor stall, and surge. The current investigation is an attempt to reduce the abovementioned phenomena. It involves the performance study of a smoothened controlled diffusion airfoil (CDA) blade that has been optimized by “Multi-Objective Genetic Algorithm” (MOGA) by altering maximum camber location and stagger angle. Inlet pressure is varied from 15 kPa to 30 kPa and the angle of attack ranging from 40.4° to 56.4°. C48-S16-BS1 is validated and considered as the baseline profile, and all other blades are collated to this.

Abstract Piston internal combustion engines used in the propulsion of ultralight aircraft are characterized by special operating conditions, especially an increased engine oil temperature. Most of the engines intended for the drive of the propeller drivetrain are air cooled. Failure to introduce an additional cooling agent so as to absorb and remove heat from the running engine makes the average lubricating oil temperature rise to about 140°C in the pistohn ring part. With such a thermal load, changes in the moments of resistance to motion of the engine are difficult to determine in the conditions of engine tests due to difficulties in temperature stabilization. The performance of aircraft engines requires taking into account many variables that are difficult to determine, which may affect changes in the moment of resistance to movement of the engine, especially when using oils of low dynamic viscosity.

Abstract Many interconnected parameters are involved in the helicopter turboshaft engine’s design, implying numerous limitations on the design process. These parameters include the key parameters such as weight, dimensions, power, specific fuel consumption, combustion temperature, air mass flow rate, and compressor pressure ratio, all of which correlate with one another and collectively affect the engine’s design process and consequently the helicopter. The first step in any design process is the conceptual design stage, where using an initial guess, an iterative parameter estimation runs until convergence. For the initial guess, a database is required, and for estimation, knowledge of the relationships between different parameters is mandatory.

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Abstract Electrostatic discharge during aircraft refueling operations has long been recognized as a safety hazard. To reduce the chances of this happening, different practices were developed, the most common being the addition of a static dissipator additive (SDA). Nowadays, the SDA is a well-established requirement in all the leading jet-fuel specifications and is in widespread use in commercial and military aviation industries. To deepen the understanding of the electrostatic behavior of nonconductive jet fuel and SDA, the Israeli Air Force (IAF) has conducted small-scale refueling tests in a simulated aircraft fuel tank. In these tests, the effect of flow rate, residence time, SDA concentration, bounding, grounding, and the method of filling were evaluated by measuring the electrostatic field strength generated. The simulation of the aircraft fuel tank was obtained using a nonconductive plastic tank jointed with a small faucet at the bottom.