Search Results (8,291)

Polyurethane (PU) is a highly versatile class of polymer utilised in many industries, including the aerospace sector. In conjunction with its superior mechanical properties, chemical resistance, and durability, it can be highly flammable depending on its form. This poses a risk aboard aircraft, which contain numerous fire hazards and cramped cabin spaces, proving an obstacle for the evacuation of passengers in an emergency. Flame-retardant additives have proven to enhance the thermal properties of polyurethane, but their toxicity and tendency to degrade mechanical performance make them unappealing. This review addresses three main topics: (1) the basic synthesis and structure of PU and modification through additives; (2) types of PU, their properties, and applications in the aerospace industry; and (3) evaluation methodologies for characterising PU performance, studying mechanical properties and thermal degradation. Several key challenges remain, including understanding the long-term durability of modified PU, optimising between fire performance and mechanical properties, improving the sustainability of PU throughout its lifetime, and validating numerical simulation as a viable testing method. This review aims to guide future research on modified PU technology to achieve safer, high-performing, and sustainable solutions for the aerospace industry and beyond. Full article

The study of aircraft gust behaviour is essential in aerodynamic and structural design and analysis, as well as in airworthiness certification. The particularities of fixed-wing Remotely Piloted Aircraft (RPA) demand a specific study of gust effects on these vehicles and their implications in RPA design and operation. The research presented here addresses the investigation of gust behaviour of RPA within the frame of conceptual design through three complementary approaches, which are respectively based on the assessment of gust and manoeuvring envelopes of RPA, the modelisation of multi-mission flight profiles of RPA towards the evaluation of the variations in gust load factor along the mission, and the analysis of the interaction of RPA conceptual design parameters with gust behaviour. These approaches are applied to various case studies, providing several key insights into the gust behaviour characteristics of RPA. These include the assessment of the operational conditions in which gust-induced stall may occur and the way in which they interact with typical mission conditions of RPA, the evaluation of the impact of mission parameters in RPA gust response along with the capability of identifying the most critical gust load factor condition for the set of considered design missions, and the ways in which undesirable gust effects may be mitigated in the conceptual design stage through the change in overall RPA design parameters. Full article

This paper offers a critical review of cutting-edge research on multi-energy microgrids (MEMs), with a novel exploration of their potential role in supporting urban air mobility (UAM), specifically electric vertical takeoff and landing (eVTOL) aircraft. While extensive research has focused on improving the economic performance and emission reductions of MEMs, particularly in the context of electric vehicle (EV) charging, there remains a significant gap in understanding how microgrids can support the decarbonization of UAM. The paper examines the opportunities and challenges of integrating microgrids with UAM operations, highlighting the need for more research to optimize energy management systems that balance renewable energy use with the growing demand for aerial transport. Thermal energy storage systems are emphasized as a critical component for addressing transportation energy needs, offering a promising solution to reduce carbon emissions while enhancing system efficiency. This review aims to provide new insights into how the coupling of microgrids and UAM can contribute to the development of economically and environmentally sustainable smart cities. Full article

Liquid hydrogen (LH₂) has been identified as a potential solution to the ever-growing climate impact of the aviation sector. One of the key problems for the industry remains the provision of the necessary storage volume, which results from the low density of hydrogen. The objective of this paper is to quantify the potential for structurally integrated conformal wing tanks for liquid hydrogen. The three wing tanks derived for the CHoSe project contain internal rib structures and are placed inside the center wingbox as well as from wing root to kink. The multidisciplinary aircraft design environment BLADE has been extended by the capabilities to complement liquid hydrogen fuselage tanks with wing tanks of varying area mass. Comparing short-to-medium range (SMR) aircraft with only fuselage tanks and with additional wing tanks resulted in key findings: for similar area mass assumptions for fuselage and wing tanks of 20 kg/m², no fuel burn benefit could be achieved. The decrease in fuselage length could not compensate for the increased structural tank masses. No significant load alleviation effect on the wing structure can be expected due to the limited mass and lever arm of the tanks inside the wing. Small efficiency gains can only be expected when synergistic stiffening effects with the load-carrying structure of the wings reduce the effective added area mass to lower values than for the fuselage tanks. Adding tanks further outbound than the wing kink deteriorates the performance, even for the most optimistic tank assumptions. Full article

Outer rotor permanent magnet synchronous motors (ORPMSMs) are widely used in drone and aircraft propulsion due to their high power density. However, conventional arc-shaped designs involve an inherent trade-off between efficiency and torque ripple. Increasing the arc curvature improves the sinusoidal air gap flux density and reduces torque ripple, but it also increases rotor eddy current loss due to larger flux variations, thereby degrading efficiency. This paper investigates the effects of stator and rotor geometries on rotor eddy current loss and torque ripple in ORPMSMs. To address this trade-off, arc- and rectangular-shaped rotor and stator pole shoes are combined to form four design candidates. Their electromagnetic performance is evaluated using finite element analysis. Based on this comparison, a configuration with rectangular rotor and stator pole shoes is selected as the initial design and further optimized using a multi-objective genetic algorithm to simultaneously improve efficiency and torque ripple. The optimized design demonstrates significant improvements, achieving reductions of 56.67% in peak-to-peak torque ripple and 46.89% in rotor eddy current loss compared to the initial design. Full article

Airfield lighting control (ALC) is critical for ensuring safe, efficient, and compliant airport operations, especially under low-visibility conditions. However, current centralized control architectures cannot adequately meet the real-time responsiveness, scalability, and reliability requirements of Advanced Surface Movement Guidance and Control Systems (A-SMGCS) Level IV. To overcome these limitations, this paper proposes a novel cloud–edge–end collaborative architecture for a mobile ALC scenario, in which we formulate a joint task computing and energy consumption optimization problem to maximize long-term system utility under latency, computation, and communication constraints. In this way, the mobile airfield lighting (MAL) system can also quickly adapt its optimal formation pattern based on the airport environment, lighting conditions, and the type of aircraft taking off or landing via efficient computation, thereby achieving the best navigational assistance effect. For solving such an optimization problem, a framework that combines K-medoids with the Improved Twin Delayed Deep Deterministic Policy Gradient (ITD3) is proposed to integrate the efficiency of clustering for rough allocation and the high-precision dynamic optimization capability of the improved TD3. The training depends on edge nodes and the cloud to achieve online performance. Finally, the extensive simulation proved that our novel algorithm is efficient. Full article

Providing regulation-compliant, high-fidelity training in aircraft maintenance remains challenging for institutions of education, where access to real aircraft, specialist tools, and operational environments is limited by cost, safety, and resource factors. This paper presents the design, in-house development, and pilot deployment of a virtual reality (VR) training system for an operationally critical maintenance procedure—Airbus A320 nose landing gear (NLG) wheel removal, strictly following the official Airbus Aircraft Maintenance Manual (AMM). Managed by an Agile-based methodology, the application, programmed with the Unity engine, uses full-size 3D CAD models and domain-expert input iteratively for quality-assured and rapid deployment. The system was piloted with aeronautical engineering students at the Vietnam Aviation Academy (VAA), achieving significant engagement and perceived gains for procedure knowledge and skill development. Positive comments emphasized the realistic, interactive, and repeatable quality of the simulation. Usability issues related to controller handling, cybersickness, and the absence of haptic feedback, however, suggest opportunities for refinement. This paper reports an early published case study of VR use in commercial aircraft maintenance training that is practically replicable and scalable, and developed in alignment with applicable civil aviation procedural requirements. It suggests that such a high-fidelity VR training platform can provide an accessible solution for aviation stakeholders to help bridge classroom training and real-world application in safety-critical training contexts. Full article

The pursuit for cleaner aviation pushes research in hybrid-electric aircraft, which are far more complex systems than conventional airplanes. In this respect, the ODE4HERA European project aims to accelerate the development of such systems with the implementation of a solution-neutral Open Digital Platform, driving the design from top level requirements to virtual verification and validation. In this respect, the authors developed and integrated a flight dynamics module in a co-simulation environment aiming at the performance verification of the reference hybrid-electric aircraft through flight simulation. The implementation of a point mass model was sufficiently accurate to comply with the preliminary objectives of the project, paving the way for a higher-fidelity and more complex flight dynamics and control systems. Full article

Severe and unpredictable wind conditions significantly disrupt flight safety, mission planning, and scheduling. Traditional wind forecasting methods rely on low-resolution mesoscale models or resource-intensive instrumentation. This study evaluates the accuracy of 40 m Large-Eddy Simulations (LESs), nested within a mesoscale framework, to better resolve hazardous wind phenomena over GrandSKY, North Dakota, the first large-scale commercial Uncrewed Aircraft System (UAS) test park in the United States, serving as a hub for UAS innovation and Beyond Visual Line of Sight operations. Using low-altitude airborne observations from Meteodrone flights, satellite data, and ground-based measurements, we assess the model’s accuracy in predicting wind speed and direction during both summer and winter. Results demonstrate that the 40 m LES provides improved predictions of wind gust variability compared to the 1 km forecast, and the impact on flight safety is quantified. The LES also reveals notable discrepancies in UAS flyability predictions, which result in up to a 17% reduction in operational windows during the summer. This study’s novelty lies in using a 40 m resolution LES nested within a 1 km WRF simulation, combined with multi-source observations, to resolve low-altitude turbulence and quantify its impact on UAS operations. A 10–18% correction factor can be applied to TKE (or derived wind variability) in coarser WRF runs to better estimate maximum wind speeds without LES. The findings highlight the potential of high-resolution LES modeling to support reliable UAS operations in weather-sensitive environments, laying the groundwork for broader integration of advanced simulation techniques in national airspace management systems. Full article

This study aims to improve the accuracy of cruise-phase power consumption prediction for multirotor unmanned aerial vehicles operating under varying wind conditions. Existing parametric energy models typically retain the wind velocity vector in the ground or inertial reference frame, and this representation does not distinguish between axial drag contributions along the fuselage and lateral attitude-correction contributions perpendicular to it. The proposed framework addresses this limitation through a physics-informed coordinate transformation that projects the measured wind vector into the body frame of the aircraft using quaternion-derived heading angles, yielding separate axial and lateral wind components. These components enter the power model as two additional predictors that augment the induced-power baseline, with the axial term following a cubic airspeed–power relationship consistent with parasitic drag formulations and the lateral term following a quadratic relationship consistent with attitude-correction mechanics. The framework is validated on a publicly available flight dataset, which comprises 188 flights of a DJI Matrice 100 quadcopter across payloads of 0 to 0.75 kg, ground speeds of 4 to 12 m/s, and altitudes of 25 to 100 m. Compared with the induced-power baseline, the proposed model reduces the root mean square error by 15.9% and the mean squared error by 29.7% during the cruise phase. The improvement is larger when wind speeds exceed 6 m/s, a regime in which the baseline residuals increase while the proposed model retains a comparatively stable error profile. Residual analysis indicates that baseline errors follow an approximately quadratic trend relative to the axial and lateral wind components, consistent with established parasitic-power and attitude-correction formulations. The closed-form structure of the proposed model is compatible with onboard execution on flight controllers, which suggests a feasible pathway toward its use as the power-prediction module within downstream range-estimation and energy-reserve sizing routines. Full article

The design of low-emission alternative-propulsion aircraft requires multidisciplinary collaboration across distributed academic and industrial environments, challenging the applicability of conventional multidisciplinary design analysis and optimization (MDAO) frameworks. This paper presents the Holistic Collaborative MDAO Selection (HCMS) methodology, which provides a structured approach for selecting MDAO architectures based on socio-technical feasibility (intellectual property protection, disciplinary autonomy, and IT governance) and computational feasibility (coupling strength and model fidelity). The methodology supports a transition from centralized to distributed workflows while ensuring secure and efficient cross-organizational integration. The approach is demonstrated through a multi-institutional case study of a dual-fuel (hydrogen and kerosene) business jet using Remote Component Environment (RCE) and Common Parametric Aircraft Configuration Schema (CPACS). Results demonstrate that the proposed methodology enables stable and scalable distributed MDAO execution while explicitly accounting for socio-technical constraints, with consistent convergence behavior and communication overhead (approximately 25 s per iteration) remaining small relative to disciplinary computation time. The case study further illustrates the impact of hydrogen integration, showing an increase in operating empty weight of approximately 14.06% for a 600 NM mission and a reduction in kerosene capacity of approximately 12.9%, while enabling hydrogen-powered operation for the primary mission segment. These findings confirm that the proposed framework effectively supports secure, collaborative MDAO under realistic socio-technical constraints while providing meaningful system-level design insights. Full article

Aircraft emergency hydraulic pumps are safety-critical units whose intermittent operation complicates condition assessment and reduces the diagnostic value of conventional bulk physicochemical oil properties. This study evaluates the applicability of tribotechnical oil analysis for monitoring degradation of the NP-27T emergency hydraulic pump under controlled bench conditions. Four NP-27T units were tested on a dedicated hydraulic bench, and oil samples were collected at defined intervals during operation and after test completion. The diagnostic methodology combined elemental spectrometry (ICP-OES), particle counting interpreted with reference to ISO 4406, and analytical ferrography. The results showed that flow performance deterioration was accompanied by measurable changes in oil-borne wear indicators, although the sensitivity of the individual diagnostic channels varied among the tested units. In several cases, the coarse particle fraction (>15 μm) exhibited the clearest response to degradation, while Fe and Cu concentrations provided useful but not uniformly monotonic trends across all pumps. Using a pragmatic early warning criterion based on the first exceedance of 100 particles/mL in the >15 μm fraction, the coarse particle signal provided lead times of approximately 13–345 min before the flow-based rejection limit was reached in the four tested units. Ferrographic analysis identified cutting and fatigue debris, together with larger wear particles, in units approaching or reaching the flow-based rejection limit. Overall, the findings demonstrate that the combined use of elemental analysis, particle counting, and ferrography provides a practical multi-indicator framework for relating oil-diagnostic signals to functional degradation of the NP-27T hydrogenerator. Under the present bench conditions, flow proved to be a more sensitive degradation indicator than pressure. The proposed approach therefore represents a useful complementary tool for maintenance decision-making and for integration with vibration-based condition monitoring of aircraft hydraulic systems. Full article

The International Civil Aviation Organization (ICAO) sets strict limits for aircraft ramp noise, a key source of which is Auxiliary Power Unit (APU) inlet noise. This paper presents a systematic and computationally efficient design methodology for APU inlet mufflers. The high-frequency noise necessitates validating a single-degree-of-freedom liner impedance model up to 10,000 Hz. The core innovation overcomes prohibitive full-passage simulation costs (days) by optimally selecting attenuation center frequencies from the source spectrum and implementing an axially segmented design. This approach enables efficient, targeted optimization (minutes per case) and leverages acoustic mode scattering at segment interfaces to enhance overall attenuation. The design is verified via high-fidelity, full-flow-path simulation. Experimental validation under various operating conditions shows good agreement with predictions, achieving approximately 9 dB reduction in overall A-weighted Sound Power Level (OASPL) with consistent performance. The results demonstrate the feasibility and effectiveness of the proposed rapid, precise, and efficient design framework. Full article

Morphing aircraft, which are capable of adaptively changing their configurations in response to mission requirements and flight environments to achieve improved aerodynamic performance, have become an important direction in aircraft design. Since the unsteady aerodynamic characteristics during continuous wing morphing differ from those in corresponding quasi-steady states, evaluating dynamic aerodynamic effects during morphing is important. In this study, a surface-based dynamic mesh approach was developed based on a spring-analogy method to simulate continuous wing morphing processes. The method employed a surface-driven mesh motion strategy, in which prescribed analytical motion of surface nodes was propagated into the volume mesh without relying on global interpolation procedures. By coupling this approach with a CFD solver, unsteady simulations of a continuously stretching wing were performed. Numerical examples showed consistent results between moving-mesh and fixed-mesh simulations. Further simulations under subsonic, transonic, and supersonic conditions allowed analysis of aerodynamic responses during continuous morphing. The proposed approach provides a numerical framework for unsteady aerodynamic simulations involving continuous surface deformation. Full article

In this work we propose a new strategy for the optimization of the flap position of a high-lift configuration in the framework of a hybrid electric regional aircraft. The approach is based on the multidisciplinary design optimization software GEMSEO and the high-performance CFD solver CODA. The CFD solver CODA solves the RANS equations on a body-fitted mesh along with immersed boundary methods, while the package GEMSEO employs the COBYQA optimization algorithm. The main airfoil is meshed in a body-fitted fashion, and a refined region is created just where the flap can be located. The employment of immersed boundary methods allows us to arbitrarily change the deflection angle and leading edge position of the flap inside this refined region without the need of remeshing the whole computational domain. The main advantage of this methodology with respect to a full body-fitted mesh scheme is the computational efficiency when hundreds or thousands of CFD-RANS simulations are required by the optimizer. We demonstrate the effectiveness of this optimization methodology in the computation of the optimal configuration of the flap during takeoff and landing phases of a high-lift airfoil. Full article