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Abstract Water quality monitoring is needed for the effective management of water resources. Periodic sampling and regular inspection/analysis allow one to classify water and identify changes or trends in water quality over time. This article presents a novel concept of an Amphibious Hybrid Unmanned Aerial Vehicle (AHUAV) that can operate in air and water for rapid water sampling, real-time water quality analysis, and water body management. A methodology using the developed AHUAV system for water body management has also been proposed for an easier and effective way of monitoring water bodies using advanced drone technologies. Using drones for water body management can be a cost-effective and efficient way of carrying out regular inspections and continual monitoring.

Abstract The ground-effect problems of loss of thrust and fountain-effect instabilities are quantified. Experiments to control and augment ground-effect lift and stability are presented, including jet momentum reflection and fountain redirection using various types of internal and external underbody ventral strakes. By strategically designing the vertical takeoff and landing (VTOL) ventral surface, reflection of the impinging fountain momentum is possible so that instead of losing 10% thrust while in ground-effect, remarkably, thrust is augmented 10% or more to a considerable height above the ground, in addition to stabilizing random pitch and roll moments caused by fountain instability.

Abstract This article presents a new machine learning (ML) development lifecycle which will constitute the core of the new aeronautical standard on ML called AS6983, jointly being developed by working group WG-114/G34 of EUROCAE and SAE. The article also presents a survey of several existing standards and guidelines related to ML in aeronautics, automotive, and industrial domains by comparing and contrasting their scope, purpose, and results.

Abstract The range of an aircraft is determined by the amount of energy that its batteries can store. Today, larger batteries are used to increase the range of electric vehicles, although energy efficiency decreases as the weight of the vehicles increases. Among the elements, lithium (Li) is the lightest and has the highest electrochemical potential. Therefore, the use of Li-ion batteries is recommended for hybrid aircraft. In addition, Li-ion batteries are the most common type of battery that is used in portable electronic devices such as smartphones, tablets, and laptops. However, Li-ion batteries may explode due to temperature. Therefore, the thermal analysis of Li-ion batteries was investigated both experimentally and numerically. Li-ion batteries were connected in series (the number is 9). Noboru’s theory of heat generation was discussed in the estimation of energy data.

Abstract Small uncrewed aircraft systems (sUAS) growth continues for recreational and commercial applications. By 2025, the Federal Aviation Administration (FAA) predicts the sUAS fleet to number nearly 2.4 million units. As sUAS operations expand within the National Airspace System (NAS), so too does the probability of near midair collisions (NMACs) between sUAS and aircraft. Currently, the primary means of recognizing sUAS NMACs rely on pilots to visually spot and evade conflicting sUAS. Pilots may report such encounters to the FAA as UAS Sighting Reports. Sighting reports are of limited value as they are highly subjective and dependent on the pilot to accurately estimate range and altitude information. Moreover, they do not account for NMACs that an aircrew member does not spot.

Abstract Threat identification and security analysis have become mandatory steps in the engineering design process of high-assurance systems, where successful cyberattacks can lead to hazardous property damage or loss of lives. This article describes a novel approach to perform security analysis on embedded systems modeled at the architectural level. The tool, called Security Threat Evaluation and Mitigation (STEM), associates threats from the Common Attack Pattern Enumeration and Classification (CAPEC) library with components and connections and suggests potential defense patterns from the National Institute of Standards and Technology (NIST) Special Publication (SP) 800-53 security standard. This article also provides an illustrative example based on a drone package delivery system modeled in AADL.

Abstract Aircraft cybersecurity efforts have tended to focus at the strategic or tactical levels without a clear connection between the two. There are many excellent engineering tools already in widespread use, but many organizations have not yet integrated and linked them into an overarching “campaign plan” that connects those tactical actions such as process hazard analysis, threat modeling, and probabilistic methods to the desired strategic outcome of secure and resilient systems. This article presents the combined systems security engineering process (CSSEP) as a way to fill that gap. Systems theory provides the theoretical foundation on which CSSEP is built. CSSEP is structured as a control loop in which the engineering team is the controller of the design process. The engineering team needs to have an explicit process model on how systems should be secured, and a control algorithm that determines what control actions should be selected.

Abstract A novel geometry for a six degrees of freedom (6DOF) unmanned aerial vehicle (UAV) rotary wing aircraft is introduced and a flight mechanical analysis is conducted for an aircraft built in accordance to the thrust vectors of the proposed geometry. Furthermore, the necessary mathematical operations and control schemes are derived to fly an aircraft with the proposed geometry. A system identification of the used propulsion system with the necessary thrust reversal in the form of bidirectional motors and propellers was conducted at a whirl tower. The design of the first prototype aircraft is presented as well as the first flight test results. It could be demonstrated that an aircraft with the thrust vectors oriented according to the proposed geometry works sufficiently and offers unique maneuvering capabilities that cannot be reached with a conventional design.

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.

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Abstract Statistical machine learning classification methods have been widely used in the fault detection analysis in several engineering domains. This motivates us to provide in this article an overview on the application of these methods in the fault diagnosis strategies and also their successful use in unmanned aerial vehicles (UAVs) systems. Different existing aspects including the implementation conditions, offline design, and online computation algorithms as well as computation complexity and detection time are discussed in detail. Evaluation and validation of these aspects have been ensured by a simple demonstration of the basic classification methods and neural network techniques in solving the fault detection and diagnosis problem of the propulsion system failure of a multirotor UAV. A testing platform of an Hexarotor UAV is completely realized.

Abstract The numerical analysis of the three-dimensional (3D) flow over a National Advisory Committee for Aeronautics (NACA) 6321 airfoil to evaluate the mass flow rate by using a novel method Improved Blowing and Suction System (IBSS) to control the boundary layer is presented in this study. Analysis is performed based on 3D Reynolds-Averaged Navier-Stokes (RANS) equation with a K-omega SST solver. The aerodynamic performance of the NACA 6321 is analyzed at a Mach number of 0.10 with three different mass flow rates, namely, 0.08 kg/s, 0.10 kg/s, and 0.12 kg/s. From the study, it is seen that when the mass flow rate decreased, the aerodynamics performance also reduced, and the aerodynamic performance improved with the increase in mass flow rate.

Abstract The civil aircraft nosewheel is clamped, lifted, and retained through the pick-up and holding system of the towbarless towing vehicle (TLTV), and the aircraft may be moved from the parking position to an adjacent one, the taxiway, a maintenance hangar, a location near the active runway, or conversely only with the power of the TLTV. The TLTV interfacing with the nose-landing gear of civil transport aircraft for the long-distance towing operations at a high speed could be defined as a towbarless aircraft taxiing system (TLATS). The dynamic loads induced by the system vibration may cause damage or reduce the certified safe-life limit of the nose-landing gear or the TLTV when the towing speed increases up to 40 km/h during the towing operations due to the maximum ramp weight of a heavy aircraft.

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 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 Transient numerical simulations are conducted over a NACA 0012 airfoil with triangular protrusions at a Reynolds number (Re) of 100000 using the γ-Reθ transition Shear Stress Transport (SST) turbulence model. Protrusions of heights 0.5%c, 1%c, and 2%c are placed at one of the three locations, viz, the leading edge (LE), 5%c on the suction surface, and 5%c on the pressure surface, while the angle of attack (AOA) is varied between 0° and 20°. Results obtained from the time-averaged solution of the unsteady Navier-Stokes equation indicate that the smaller protrusion placed at 5%c on the suction surface improves the post-stall lift coefficient by up to 59%, without altering the pre-stall characteristics. The improvement in time-averaged lift coefficients comes with enhanced flow unsteadiness due to vigorous vortex shedding.

Abstract The study aims to design a roadmap of the turboelectric propulsion system’s power system architecture, which is based on the Inner Bus Tie Architecture proposed by the National Aeronautics and Space Administration (NASA). The single turboshaft engine shutdown failure mode is analyzed and simulated on MATLAB/Simulink. A General Electric (GE) T700 turboshaft engine is preferred in constructing a turboshaft engine mathematical model. The constructed mathematical model is integrated into NASA’s Inner Bus Tie Architecture. As a result, mechanical to electrical conversion efficiency and power balance of the system is derived. Element sizing is accomplished. Preliminary power requirements for generators, power converters, and electrical motors are calculated to generate a roadmap for future applications. Finally, it is observed that the simulations are found efficient and quite acceptable for such applications.

Abstract The airline industry faces a crisis in the future as consumer demand is increasing, but the environmental effects and depleting resources of kerosene mean that growth is unsustainable. Hydrogen is touted as the leading candidate to replace kerosene, but it needs significant technological and economical endeavors. In such a scenario, cryogenic liquid hydrogen (LH2) is predicted to be the most feasible method of using hydrogen. The major challenge of LH2 as an aircraft fuel is that it requires approximately four times the storage volume of kerosene—due to its lower density. Thus the design of cryogenic storage tanks to handle larger quantities of fuel is becoming increasingly important. But the increase in drag associated with larger storage tanks causes an increase in fuel consumption. Hence, this paper aims to evaluate the aerodynamic performance of different storage configurations and aid in the selection of an economic and efficient storage system.

Abstract Despite more and more rigorous defense mechanisms in place for cyber-physical systems, cybercriminals are increasingly attacking systems for benefits using a variety of means including malware, phishing, ransomware, and denial of service. Cyberattacks could not only cause significant economic loss but also disastrous consequences for individuals and organizations. Therefore, it is advantageous to detect and fix potential cyber vulnerabilities before the system is fielded. To this end, this article presents a language, VERDICT, and a novel framework, Cyber Vulnerability Analysis Framework (CyVAF) to (i) define cyber threats and mitigation defenses based on system properties, (ii) detect cyber vulnerabilities of system architecture automatically, and also (iii) suggest mitigation defenses. VERDICT is developed as an annex to the Architecture Analysis and Design Language (AADL) but can also be used independently.