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Aerospace, Volume 7, Issue 7 (July 2020) – 17 articles

Cover Story (view full-size image): Bowtie analysis is a broadly used tool in risk management to identify root causes and consequences of hazards. Limitations of the method are reliance on judgement and an ad-hoc development process. Systematic approaches are needed to identify threats and consequences, and to ascertain barriers. A new conceptual framework is introduced by combining Bowtie with the 6M structure of Ishikawa to categorise threats, consequences and barriers. The method is developed for visual inspection of gas turbine components. The provided systematic methodology has the potential to result in more comprehensive Bowtie risk assessments, with a lower chance of serious omissions. View this paper.
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21 pages, 2662 KiB  
Article
3D Cruise Trajectory Optimization Inspired by a Shortest Path Algorithm
by Alejandro Murrieta-Mendoza, Charles Romain and Ruxandra Mihaela Botez
Aerospace 2020, 7(7), 99; https://doi.org/10.3390/aerospace7070099 - 21 Jul 2020
Cited by 14 | Viewed by 3997
Abstract
Aircrafts require a large amount of fuel in order to generate enough power to perform a flight. That consumption causes the emission of polluting particles such as carbon dioxide, which is implicated in global warming. This paper proposes an algorithm which can provide [...] Read more.
Aircrafts require a large amount of fuel in order to generate enough power to perform a flight. That consumption causes the emission of polluting particles such as carbon dioxide, which is implicated in global warming. This paper proposes an algorithm which can provide the 3D reference trajectory that minimizes the flight costs and the fuel consumption. The proposed algorithm was conceived using the Floyd–Warshall methodology as a reference. Weather was taken into account by using forecasts provided by Weather Canada. The search space was modeled as a directional weighted graph. Fuel burn was computed using the Base of Aircraft DAta (BADA) model developed by Eurocontrol. The trajectories delivered by the developed algorithm were compared to long-haul flight plans computed by a European airliner and to as-flown trajectories obtained from Flightradar24®. The results reveal that up to 2000 kg of fuel can be reduced per flight, and flight time can be also reduced by up to 11 min. Full article
(This article belongs to the Special Issue Aircraft Trajectory Design and Optimization)
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17 pages, 1988 KiB  
Article
A Practical Approach to Monitor Capacity under the CDM Approach
by Catya Zuniga and Geert Boosten
Aerospace 2020, 7(7), 101; https://doi.org/10.3390/aerospace7070101 - 21 Jul 2020
Cited by 3 | Viewed by 5023
Abstract
The operations of take-off and landing at hub airports are often subject to a wide variety of delays; the effects of these delays impact not only the related stakeholders, such as aircraft operators, air-traffic control unity and ground handlers but as part of [...] Read more.
The operations of take-off and landing at hub airports are often subject to a wide variety of delays; the effects of these delays impact not only the related stakeholders, such as aircraft operators, air-traffic control unity and ground handlers but as part of the European network, delays are propagated through the network. As a result, Airport Collaborative Decision Making (A-CDM) is being employed as a methodology for increasing the efficiency of Air Traffic Management (ATM), through the involvement of partners within the airports. Under CDM, there are some strategic common objectives regardless the airport or the partner specific interest to improve operational efficiency, predictability and punctuality to the ATM network and airport stakeholders. Monitoring and controlling some strategic areas such as, Efficiency, Capacity, Safety and Environment is needed to achieve the benefits. Therefore, the present work aims to provide a framework to monitor the accuracy of capacity in the three main flight phases. It aims to provide a comprehensible and practical approach to monitoring capacity by identifying and proposing Key Performance Indicators (KPIs) based on the A-CDM Milestone Approach to optimise the use of available capacity. To illustrate our approach, Amsterdam Airport Schiphol is used as case study as a full A-CDM airport. Full article
(This article belongs to the Special Issue Aircraft Trajectory Design and Optimization)
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14 pages, 16350 KiB  
Article
ADS-B Like UTM Surveillance Using APRS Infrastructure
by Ying-Hong Lin, Chin E. Lin and Hsu-Chan Chen
Aerospace 2020, 7(7), 100; https://doi.org/10.3390/aerospace7070100 - 21 Jul 2020
Cited by 5 | Viewed by 4106
Abstract
Automatic packet reporting system (APRS) is selected as a candidate for automatic dependent surveillance-broadcast (ADS-B) like solution for unmanned aircraft system traffic management (UTM). The APRS on-board unit (OBU) at 0.5 W radio power and a proper ground transceiver station (GTS) deployment together [...] Read more.
Automatic packet reporting system (APRS) is selected as a candidate for automatic dependent surveillance-broadcast (ADS-B) like solution for unmanned aircraft system traffic management (UTM). The APRS on-board unit (OBU) at 0.5 W radio power and a proper ground transceiver station (GTS) deployment together makes up the infrastructure for unmanned aerial vehicle (UAV) surveillance. The airborne APRS OBU, designed and built using an available LightAPRS module, and the GTS to relay received data into the UTM Cloud is developed in this study. By system integration, the APRS OBU reports position data and flight data periodically to UTM Cloud. This paper presents the development of the ADS-B like operation for UTM using APRS. To avoid communication jamming by HAMs, the adopted APRS shifts its carrying frequency from 144.64 MHz to 144.61 MHz. In addition, the data period is tuned to around 10 s to test its functional capability. The APRS OBU downlinks 90 bytes of surveillance data onto the UTM cloud using the Internet, including position and flight data from Pixhawk flight controller (FC). A series of system performance verifications are conducted to examine APRS ADS-B like reliability and continuity with coverage limit. Through 19 flight tests, the GTS collected 1330 packets of data out of 1331 transmitted from the APRS OBU. Each data packet has the complete 90 bytes for surveillance with position and six degree-of-freedom (DoF) flight data on the UTM cloud. The APRS GTS deployment, with a low rate of missing data, covers a 40 km radius at the specific frequency of 144.61 MHz. The test results verify the functional capability of APRS to support an ADS-B like for UTM in Taiwan. Full article
(This article belongs to the Special Issue Unmanned Aircraft Traffic Management)
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21 pages, 5387 KiB  
Article
UWE-4: First Electric Propulsion on a 1U CubeSat—In-Orbit Experiments and Characterization
by Alexander Kramer, Philip Bangert and Klaus Schilling
Aerospace 2020, 7(7), 98; https://doi.org/10.3390/aerospace7070098 - 17 Jul 2020
Cited by 23 | Viewed by 6079
Abstract
The electric propulsion system NanoFEEP was integrated and tested in orbit on the UWE-4 satellite, which marks the first successful demonstration of an electric propulsion system on board a 1U CubeSat. In-orbit characterization measurements of the heating process of the propellant and the [...] Read more.
The electric propulsion system NanoFEEP was integrated and tested in orbit on the UWE-4 satellite, which marks the first successful demonstration of an electric propulsion system on board a 1U CubeSat. In-orbit characterization measurements of the heating process of the propellant and the power consumption of the propulsion system at different thrust levels are presented. Furthermore, an analysis of the thrust vector direction based on its effect on the attitude of the spacecraft is described. The employed heater liquefies the propellant for a duration of 30 min per orbit and consumes 103 ± 4 mW. During this time, the respective thruster can be activated. The propulsion system including one thruster head, its corresponding heater, the neutralizer and the digital components of the power processing unit consume 8.5 ± 0.1 mW · μ A−1 + 184 ± 8.5 mW and scales with the emitter current. The estimated thrust directions of two thruster heads are at angles of 15.7 ± 7.6∘ and 13.2 ± 5.5∘ relative to their mounting direction in the CubeSat structure. In light of the very limited power on a 1U CubeSat, the NanoFEEP propulsion system renders a very viable option. The heater of subsequent NanoFEEP thrusters was already improved, such that the system can be activated during the whole orbit period. Full article
(This article belongs to the Special Issue Electric Propulsion)
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19 pages, 4926 KiB  
Article
Filtering-Based Three-Axis Attitude Determination Package for Spinning Spacecraft: Preliminary Results with Arase
by Halil Ersin Soken, Shin-ichiro Sakai, Kazushi Asamura, Yosuke Nakamura, Takeshi Takashima and Iku Shinohara
Aerospace 2020, 7(7), 97; https://doi.org/10.3390/aerospace7070097 - 13 Jul 2020
Cited by 7 | Viewed by 3557
Abstract
JAXA’s ERG (Exploration of Energization and Radiation in Geospace) Spacecraft, which is nicknamed Arase, was launched on 20 December 2016. Arase is a spin-stabilized and Sun-oriented spacecraft. Its mission is to explore how relativistic electrons in the radiation belts are generated during space [...] Read more.
JAXA’s ERG (Exploration of Energization and Radiation in Geospace) Spacecraft, which is nicknamed Arase, was launched on 20 December 2016. Arase is a spin-stabilized and Sun-oriented spacecraft. Its mission is to explore how relativistic electrons in the radiation belts are generated during space storms. Two different on-ground attitude determination algorithms are designed for the mission: A TRIAD-based algorithm that inherits from old missions and a filtering-based new algorithm. This paper, first, discusses the design of the filtering-based attitude determination algorithm, which is mainly based on an Unscented Kalman Filter (UKF), specifically designed for spinning spacecraft (SpinUKF). The SpinUKF uses a newly introduced set of attitude parameters (i.e., spin-parameters) to represent the three-axis attitude of the spacecraft and runs UKF for attitude estimation. The paper then presents the preliminary attitude estimation results for the spacecraft that are obtained after the launch. The results are presented along with the encountered challenges and suggested solutions for them. These preliminary attitude estimation results show that the expected accuracy of the fine attitude estimation for the spacecraft is less than 0.5°. Full article
(This article belongs to the Special Issue Spacecraft Attitude Determination and Control)
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11 pages, 3720 KiB  
Article
SITAEL HC1 Low-Current Hollow Cathode
by Daniela Pedrini, Cosimo Ducci, Ugo Cesari, Tommaso Misuri and Mariano Andrenucci
Aerospace 2020, 7(7), 96; https://doi.org/10.3390/aerospace7070096 - 10 Jul 2020
Cited by 9 | Viewed by 4204
Abstract
SITAEL is active in the field of electric propulsion and is involved in the development of different thruster technologies—mainly Hall thrusters (HTs)—of power levels ranging from 100 W up to 20 kW. Low-power HTs are the most effective choice to perform orbit transfer, [...] Read more.
SITAEL is active in the field of electric propulsion and is involved in the development of different thruster technologies—mainly Hall thrusters (HTs)—of power levels ranging from 100 W up to 20 kW. Low-power HTs are the most effective choice to perform orbit transfer, drag compensation, and de-orbiting maneuvers for small satellites. This paper is dedicated to the activities regarding HC1, the hollow cathode conceived for the 100-W-class Hall thruster under development at SITAEL. Successful test campaigns were performed and are described, with emphasis on the improvements in the cathode design after an extensive research and development phase. The results are presented and discussed, along with future developments of the ongoing activities. Full article
(This article belongs to the Special Issue Micro-Propulsion Systems and Components for Small Spacecraft—Current Trends, Innovations and Challenges)
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28 pages, 9014 KiB  
Article
Effects of Thermal Cycle and Ultraviolet Radiation on 3D Printed Carbon Fiber/Polyether Ether Ketone Ablator
by Farhan Abdullah, Kei-ichi Okuyama, Akito Morimitsu and Naofumi Yamagata
Aerospace 2020, 7(7), 95; https://doi.org/10.3390/aerospace7070095 - 08 Jul 2020
Cited by 25 | Viewed by 4965
Abstract
The extreme heating environment during re-entry requires an efficient heat shield to protect a spacecraft. The current method of manufacturing a heat shield is labor intensive. The application of 3D printing can reduce cost and manufacturing time and improve the quality of a [...] Read more.
The extreme heating environment during re-entry requires an efficient heat shield to protect a spacecraft. The current method of manufacturing a heat shield is labor intensive. The application of 3D printing can reduce cost and manufacturing time and improve the quality of a heat shield. A 3D printed carbon fiber/polyether ether ketone (CF/PEEK) composite was proposed as a heat shield material. The aim was to develop a heat shield and the structural member as a single structure while maintaining the necessary recession resistance. Test samples were exposed to thermal cycles and ultraviolet (UV) radiation environment. Subsequently, a tensile test was performed to evaluate the effect of thermal cycle and UV radiation on the mechanical properties. The sample’s recession performance and temperature behavior were evaluated using an arc heated wind tunnel. Exposure to thermal cycle and UV radiation have limited effect on the mechanical properties, recession behavior and temperature behavior of 3D CF/PEEK. Results from the arc heating test showed an expansion of the sample surface and better recession resistance than other existing ablator materials. Overall, 3D CF/PEEK has excellent recession resistance while maintaining mechanical properties when exposed to high temperature, thermal cycle and UV radiation. Full article
(This article belongs to the Special Issue Additive Manufacturing for Aerospace and Defence)
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19 pages, 2198 KiB  
Article
A Lean Satellite Electrical Power System with Direct Energy Transfer and Bus Voltage Regulation Based on a Bi-Directional Buck Converter
by Juan J. Rojas, Yamauchi Takashi and Mengu Cho
Aerospace 2020, 7(7), 94; https://doi.org/10.3390/aerospace7070094 - 05 Jul 2020
Cited by 7 | Viewed by 6293
Abstract
The lean satellite approach requires aggressive measures for cutting development time and resource utilization; therefore, the power system should be simple, with a low part count, high reliability, and good electrical performance. The fully-regulated bus direct energy transfer (FRDET) architecture is considered the [...] Read more.
The lean satellite approach requires aggressive measures for cutting development time and resource utilization; therefore, the power system should be simple, with a low part count, high reliability, and good electrical performance. The fully-regulated bus direct energy transfer (FRDET) architecture is considered the most common solution for big satellites; however, it is rarely used in lean satellite designs because of its complexity and the lack of commercial off-the-shelf solutions. Based on this, a new implementation of the FRDET architecture was proposed, prototyped, and evaluated. The system was based on a bidirectional converter that charges and discharges the battery while maintaining the bus voltage regulation. The system was evaluated by comparing it with the prevailing architectures in the field, in terms of efficiency and average harvested solar power per orbit. The proposed system was superior in both aspects which made it more suitable for its application in lean satellite designs. Full article
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26 pages, 5857 KiB  
Article
On the Effects of Structural Coupling on Piezoelectric Energy Harvesting Systems Subject to Random Base Excitation
by Hamidreza Masoumi, Hamid Moeenfard, Hamed Haddad Khodaparast and Michael I. Friswell
Aerospace 2020, 7(7), 93; https://doi.org/10.3390/aerospace7070093 - 04 Jul 2020
Cited by 3 | Viewed by 3482
Abstract
The current research investigates the novel approach of coupling separate energy harvesters in order to scavenge more power from a stochastic point of view. To this end, a multi-body system composed of two cantilever harvesters with two identical piezoelectric patches is considered. The [...] Read more.
The current research investigates the novel approach of coupling separate energy harvesters in order to scavenge more power from a stochastic point of view. To this end, a multi-body system composed of two cantilever harvesters with two identical piezoelectric patches is considered. The beams are interconnected through a linear spring. Assuming a stochastic band limited white noise excitation of the base, the statistical properties of the mechanical response and those of the generated voltages are derived in closed form. Moreover, analytical models are derived for the expected value of the total harvested energy. In order to maximize the expected generated power, an optimization is performed to determine the optimum physical and geometrical characteristics of the system. It is observed that by properly tuning the harvester parameters, the energy harvesting performance of the structure is remarkably improved. Furthermore, using an optimized energy harvester model, this study shows that the coupling of the beams negatively affects the scavenged power, contrary to the effect previously demonstrated for harvesters under harmonic excitation. The qualitative and quantitative knowledge resulting from this analysis can be effectively employed for the realistic design and modelling of coupled multi-body structures under stochastic excitations. Full article
(This article belongs to the Special Issue Probabilistic Modelling and Identification in Aircraft Structures)
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30 pages, 7608 KiB  
Article
Electrospray Propulsion Engineering Toolkit (ESPET)
by Benjamin St. Peter, Rainer A. Dressler, Yu-hui Chiu and Timothy Fedkiw
Aerospace 2020, 7(7), 91; https://doi.org/10.3390/aerospace7070091 - 04 Jul 2020
Cited by 9 | Viewed by 5564
Abstract
We report on the development of a software tool, the Electrospray Propulsion Engineering Toolkit (ESPET), that is currently being shared as a web application with the purpose to accelerate the development of electrospray thruster arrays for space propulsion. ESPET can be regarded as [...] Read more.
We report on the development of a software tool, the Electrospray Propulsion Engineering Toolkit (ESPET), that is currently being shared as a web application with the purpose to accelerate the development of electrospray thruster arrays for space propulsion. ESPET can be regarded as a database of microfluidic properties and electrohydrodynamic scaling models that are combined into a performance estimation tool. The multiscale model integrates experimental high-level physics characterization of microfluidic components in a full-scale electrospray propulsion (ESP) microfluidic network performance solution. ESPET takes an engineering model approach that breaks the ESP system down into multiple microfluidic components or domains that can be described by either analytical microfluidic or reduced order numerical solutions. ESPET can be divided into three parts: a central database of critical microfluidic properties, a microfluidic domain modeler, and a microfluidic network solver. Two options exist for the network solution, a detailed multi-domain solver and a QuickSolver designed for rapid design and testing of simple three-domain reservoir-feed-emitter arrays. The multi-domain network solver exploits the Hagen–Poiseuille/Ohm’s law analogy by using the publicly available SPICE (Simulation Program with Integrated Circuit Emphasis) electric circuit simulation software to solve the flow properties of the microfluidic network. Both the multi-domain and QuickSolver solutions offer Monte Carlo analysis of arrays based on user supplied tolerances on design parameters. Benchmarking demonstration examples are provided for experimental work in the literature, as well as recent experimental work conducted at Busek Co. The demonstration examples include ionic liquid propelled systems using active and passive capillary emitters, externally wetted emitter needles, and porous glass emitters, as well as a liquid metal system based on an externally wetted emitter needle. Full article
(This article belongs to the Special Issue Electric Propulsion)
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16 pages, 1187 KiB  
Article
Effect of Characteristic Phenomena and Temperature on Super-Cooled Large Droplet Icing on NACA0012 Airfoil and Axial Fan Blade
by Toma Takahashi, Koji Fukudome, Hiroya Mamori, Naoya Fukushima and Makoto Yamamoto
Aerospace 2020, 7(7), 92; https://doi.org/10.3390/aerospace7070092 - 03 Jul 2020
Cited by 12 | Viewed by 4393
Abstract
Icing simulations involving super-cooled large droplets (SLDs) on a NACA0012 airfoil and a commercial axial fan were performed considering the characteristic behavior of SLD icing (i.e., splash-bounce, deformation, and breakup). The simulations were performed considering weak coupling between flow field and droplet motion. [...] Read more.
Icing simulations involving super-cooled large droplets (SLDs) on a NACA0012 airfoil and a commercial axial fan were performed considering the characteristic behavior of SLD icing (i.e., splash-bounce, deformation, and breakup). The simulations were performed considering weak coupling between flow field and droplet motion. The flow field was computed using the Eulerian method, wherein the droplet motion was simulated via the Lagrangian method. To represent the ice shape, an extended Messinger model was used for thermodynamic computation. The ice shape and collection efficiency of the NACA0012 airfoil derived using the icing simulation exhibited a reasonable agreement with the existing experimental data. The icing simulation results for the axial fan, in terms of distribution of ice on the blade and its influence on the flow field, indicated that flow separation occurred, and the mass flow rate of the flow passage decreased. Moreover, the splash and bounce phenomena considerably influenced the icing process; however, the effect of the deformation and breakup phenomena was negligibly small. In terms of the effect of the SLDs on the icing phenomena, it was noted that, with the decrease in the SLD temperature (from −5 °C to −15 °C), the number of adhering SLDs increased, whereas the number of splashing and bouncing SLDs decreased. Full article
(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft)
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28 pages, 12270 KiB  
Article
Predicting Rotor Heat Transfer Using the Viscous Blade Element Momentum Theory and Unsteady Vortex Lattice Method
by Abdallah Samad, Gitsuzo B. S. Tagawa, François Morency and Christophe Volat
Aerospace 2020, 7(7), 90; https://doi.org/10.3390/aerospace7070090 - 03 Jul 2020
Cited by 12 | Viewed by 4153
Abstract
Calculating the unsteady convective heat transfer on helicopter blades is the first step in the prediction of ice accretion and the design of ice-protection systems. Simulations using Computational Fluid Dynamics (CFD) successfully model the complex aerodynamics of rotors as well as the heat [...] Read more.
Calculating the unsteady convective heat transfer on helicopter blades is the first step in the prediction of ice accretion and the design of ice-protection systems. Simulations using Computational Fluid Dynamics (CFD) successfully model the complex aerodynamics of rotors as well as the heat transfer on blade surfaces, but for a conceptual design, faster calculation methods may be favorable. In the recent literature, classical methods such as the blade element momentum theory (BEMT) and the unsteady vortex lattice method (UVLM) were used to produce higher fidelity aerodynamic results by coupling them to viscous CFD databases. The novelty of this research originates from the introduction of an added layer of the coupling technique to predict rotor blade heat transfer using the BEMT and UVLM. The new approach implements the viscous coupling of the two methods from one hand and introduces a link to a new airfoil CFD-determined heat transfer correlation. This way, the convective heat transfer on ice-clean rotor blades is estimated while benefiting from the viscous extension of the BEMT and UVLM. The CFD heat transfer prediction is verified using existing correlations for a flat plate test case. Thrust predictions by the implemented UVLM and BEMT agree within 2% and 80% compared to experimental data. Tip vortex locations by the UVLM are predicted within 90% but fail in extreme ground effect. The end results present as an estimate of the heat transfer for a typical lightweight helicopter tail rotor for four test cases in hover, ground effect, axial, and forward flight. Full article
(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft)
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13 pages, 1394 KiB  
Article
Modelling and Simulation of Transpiration Cooling Systems for Atmospheric Re-Entry
by Deep Bandivadekar and Edmondo Minisci
Aerospace 2020, 7(7), 89; https://doi.org/10.3390/aerospace7070089 - 01 Jul 2020
Cited by 2 | Viewed by 4328
Abstract
Aerothermodynamic heating is one of the primary challenges faced in progressing towards reliable hypersonic transportation. In the present study, the transpiration cooling method applied to the thermal protection system of re-entry vehicles is investigated. The complexity in analysing the incoming heat flux for [...] Read more.
Aerothermodynamic heating is one of the primary challenges faced in progressing towards reliable hypersonic transportation. In the present study, the transpiration cooling method applied to the thermal protection system of re-entry vehicles is investigated. The complexity in analysing the incoming heat flux for re-entry lies not only in the extreme conditions of the flow but also in the fact that the coolant flow through the porous medium needs to be treated appropriately. While the re-entering spacecraft passes through various flow regimes, the peak conditions are faced only near continuum regime. Focusing on these conditions, traditional computational fluid dynamics techniques are used to model transpiration cooling for re-entry vehicles. In the current work, the open source CFD framework OpenFOAM is used to couple two different solvers iteratively and then analyse the thermal response for flow speed conditions typical of re-entry vehicles. Independent computations are performed using the explicit, loosely coupled procedure for high speed argon flow over a 2D axi-symmetrical cylindrical vehicle. The results presented indicate distinct heat flux drop along the surface of the cylindrical vehicle as a function of parameters such as coolant pressure and wall temperature. Full article
(This article belongs to the Special Issue Cooling/Heat Transfer)
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22 pages, 11972 KiB  
Article
Development of a Morphing Landing Gear Composite Door for High Speed Compound Rotorcraft
by Antonio Chiariello, Salvatore Orlando, Pasquale Vitale, Mauro Linari, Raffaele Longobardi and Luigi Di Palma
Aerospace 2020, 7(7), 88; https://doi.org/10.3390/aerospace7070088 - 30 Jun 2020
Cited by 6 | Viewed by 8002
Abstract
In the framework of fast rotorcraft, smoothness and flushness of external aerodynamic surfaces present challenges for high-speed conditions, where aerodynamics is the driver of helicopter performance. For AIRBUS-RACER helicopter the main landing gear trap doors are parts of the lower wing skins (in [...] Read more.
In the framework of fast rotorcraft, smoothness and flushness of external aerodynamic surfaces present challenges for high-speed conditions, where aerodynamics is the driver of helicopter performance. For AIRBUS-RACER helicopter the main landing gear trap doors are parts of the lower wing skins (in retracted configuration) affecting helicopter performance by minimizing the drag. Flushness requirements must not be in contrast with the functionally of the Landing gear system that must open and close the doors during the landing gear retraction-extension phases at moderately low velocity. To manage these goals, a novel design logic has been identified to support the trap doors development phase. The identified way to proceed needs of relevant numerical method and tool as well. This method is aimed at identifying the main landing gear composite compartment doors in pre-shaped configuration to match the smoothness and door-stopper engagements over each aerodynamic conditions. The authors propose a detailed non-linear Finite Element method, based on MSC Nastran (MSC Software, Newport Beach, US) SOL-400 solver in which the structure is modelled with deformable contact bodies in a multiple load step sequence, open door condition and pre-shaped, deformed under actuator pre-load, under flight load conditions. The method includes the entire pre-stressed field due to the preload and the actual door stiffness, considering the achieved large displacement to verify the most representative strain field during loads application. The paper defines a robust methodology to predict the deformation and ensure the most appropriate door “pre-bow” and pre-load, in order to achieve the desiderated structural shape that matches aerodynamic requirements. The main result is the identification of a pre-shaped doors configuration for the Airbus RACER Fast Rotorcraft. Full article
(This article belongs to the Special Issue Adaptive/Smart Structures and Multifunctional Materials in Aerospace)
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28 pages, 16233 KiB  
Article
Multi-Fidelity Design Optimization of a Long-Range Blended Wing Body Aircraft with New Airframe Technologies
by Stanislav Karpuk, Yaolong Liu and Ali Elham
Aerospace 2020, 7(7), 87; https://doi.org/10.3390/aerospace7070087 - 30 Jun 2020
Cited by 22 | Viewed by 6230
Abstract
The German Cluster of Excellence SE²A (Sustainable and Energy Efficient Aviation) is established in order to investigate the influence of game-changing technologies on the energy efficiency of future transport aircraft. In this paper, the preliminary investigation of the four game-changing technologies active flow [...] Read more.
The German Cluster of Excellence SE²A (Sustainable and Energy Efficient Aviation) is established in order to investigate the influence of game-changing technologies on the energy efficiency of future transport aircraft. In this paper, the preliminary investigation of the four game-changing technologies active flow control, active load alleviation, boundary layer ingestion, and novel materials and structure concepts on the performance of a long-range Blended Wing Body (BWB) aircraft is presented. The BWB that was equipped with the mentioned technologies was designed and optimized using the multi-fidelity aircraft design code SUAVE with a connection to the Computational Fluid Dynamics (CFD) code SU2. The conceptual design of the BWB aircraft is performed within the SUAVE framework, where the influence of the new technologies is investigated. In the second step, the initially designed BWB aircraft is improved by an aerodynamic shape optimization while using the SU2 CFD code. In the third step, the performance of the optimized aircraft is evaluated again using the SUAVE code. The results showed more than 60% reduction in the aircraft fuel burn when compared to the Boeing 777. Full article
(This article belongs to the Special Issue Aircraft Design (SI-2/2020))
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37 pages, 7024 KiB  
Article
A Systematic Methodology for Developing Bowtie in Risk Assessment: Application to Borescope Inspection
by Jonas Aust and Dirk Pons
Aerospace 2020, 7(7), 86; https://doi.org/10.3390/aerospace7070086 - 29 Jun 2020
Cited by 22 | Viewed by 14266
Abstract
Background—Bowtie analysis is a broadly used tool in risk management to identify root causes and consequences of hazards and show barriers that can prevent or mitigate the events to happen. Limitations of the method are reliance on judgement and an ad hoc development [...] Read more.
Background—Bowtie analysis is a broadly used tool in risk management to identify root causes and consequences of hazards and show barriers that can prevent or mitigate the events to happen. Limitations of the method are reliance on judgement and an ad hoc development process. Purpose—Systematic approaches are needed to identify threats and consequences, and to ascertain mitigation and prevention barriers. Results—A new conceptual framework is introduced by combining the Bowtie method with the 6M structure of Ishikawa to categorise the threats, consequences and barriers. The method is developed for visual inspection of gas turbine components, for which an example is provided. Originality—Provision of a more systematic methodology has the potential to result in more comprehensive Bowtie risk assessments, with less chance of serious omissions. The method is expected to find application in the broader industry, and to support operators who are non-risk experts but have application-specific knowledge, when performing Bowtie risk assessment. Full article
(This article belongs to the Special Issue Civil and Military Airworthiness: Recent Developments and Challenges (Volume II))
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29 pages, 6937 KiB  
Article
Fundamental Elements of an Urban UTM
by Tim McCarthy, Lars Pforte and Rebekah Burke
Aerospace 2020, 7(7), 85; https://doi.org/10.3390/aerospace7070085 - 27 Jun 2020
Cited by 26 | Viewed by 8556
Abstract
Urban airspace environments present exciting new opportunities for delivering drone services to an increasingly large global market, including: information gathering; package delivery; air-taxi services. A key challenge is how to model airspace environments over densely populated urban spaces, coupled with the design and [...] Read more.
Urban airspace environments present exciting new opportunities for delivering drone services to an increasingly large global market, including: information gathering; package delivery; air-taxi services. A key challenge is how to model airspace environments over densely populated urban spaces, coupled with the design and development of scalable traffic management systems that may need to handle potentially hundreds to thousands of drone movements per hour. This paper explores the background to Urban unmanned traffic management (UTM), examining high-level initiatives, such as the USA’s Unmanned Air Traffic (UTM) systems and Europe’s U-Space services, as well as a number of contemporary research activities in this area. The main body of the paper describes the initial research outputs of the U-Flyte R&D group, based at Maynooth University in Ireland, who have focused on developing an integrated approach to airspace modelling and traffic management platforms for operating large drone fleets over urban environments. This work proposes pragmatic and innovative approaches to expedite the roll-out of these much-needed urban UTM solutions. These approaches include the certification of drones for urban operation, the adoption of a collaborative and democratic approach to designing urban airspace, the development of a scalable traffic management and the replacement of direct human involvement in operating drones and coordinating drone traffic with machines. The key fundamental elements of airspace architecture and traffic management for busy drone operations in urban environments are described together with initial UTM performance results from simulation studies. Full article
(This article belongs to the Special Issue Unmanned Aircraft Traffic Management)
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