Abstract: Propulsion systems aboard small satellites assisting dynamic space missions at the proximity of deep space natural objects may face challenges in long-term non-serviceable operations, achieving thrust vector direction control, and adapting to severe environmental conditions. The proposed solution involves using pulsed plasma thrusters with multiple spark plugs for uniform ignition and thrust vector control, enhancing reliability and efficiency of propulsion system. Key advantages of the use of such an approach include minimal power consumption, efficient volume utilization, and enhanced reliability through redundant ignition points. Experimental validation confirms the effectiveness of the proposed architecture, demonstrating uniform ignition patterns and capability of thrust vector adjustment. It can be supposed that this approach supports the viability of small satellites in future deep space missions, promising dynamic, resilient, and reusable proliferated space systems.

Abstract:

In recent years, the trend toward spacecraft miniaturization has led to the widespread adoption of micro- and nanosatellites, driven by their reduced development costs and simplified launch logistics. Operating these platforms in coordinated fleets, or swarms, represents a promising approach to overcoming the inherent limitations of individual spacecraft by distributing sensing and processing capabilities across multiple units. For systems of this scale, decentralized guidance and control architectures based on so-called behavioral strategies offer an attractive solution. These approaches are inspired by biological swarms, which exhibit remarkable robustness and adaptability through simple local interactions, minimal information exchange, and the absence of centralized supervision. This work investigates the feasibility of autonomous swarm maintenance under the stringent sensing and computational constraints typical of nanosatellite platforms. Each spacecraft is assumed to carry a single monocular camera aligned with the along-track direction. The proposed behavioral control framework enables decentralized formation keeping without ground intervention or centralized coordination. Since control actions rely on the relative motion of neighboring satellites, a lightweight relative navigation capability is required. The results indicate that complex vision pipelines can be replaced by simple blob-based image processing, although accurate reconstruction of relative parameters remains essential to avoid unnecessary control effort arising from suboptimal guidance decisions

Abstract: Composite wing structures are widely used in unmanned aerial vehicles (UAVs) because of their high specific strength and stiffness, but they are vulnerable to localized impact events such as tool drops, runway debris and small bird or drone strikes. In many aerospace applications, carbon fiber–reinforced polymers (CFRP) are preferred for their high stiffness and weight efficiency, although they tend to fail in a brittle manner and are expensive. E-glass fiber composites, on the other hand, are tougher and cheaper, but usually considered less competitive in stiffness and impact resistance. This study numerically investigates the impact resistance of optimized E-glass fiber composite UAV wing skins compared with aerospace-grade carbon fiber skins, both supported by balsa-wood cores. A 3D finite element (FE) model of a 600 mm semi-span UAV wing segment was developed in Abaqus/Explicit, with a user-defined VUMAT implementing an orthotropic elastic law and a Hashin-type progressive damage model. A rigid spherical impactor (radius 8 mm) with various mass velocity combinations (0.5 kg at 5000 and 10 000 mm/s, and 1.0 kg at 20 000 mm/s) was used to represent low, medium and high energy impacts. E-glass material sets were defined and gradually improved, within realistic mechanical limits derived from published E-glass/epoxy systems, until a “maximum experimental limit” E-glass configuration was obtained. This optimized E-glass wing skin was then compared with carbon-fiber configurations taken as benchmark aerospace. The comparison is based on peak contact force, penetration or non-penetration, absorbed energy, and damage extent in the skin and sub-structure. The study also proposes a coupon- and sub-component-level experimental programme to validate the numerical predictions using drop-weight impact tests on E-glass and carbon-fiber laminates and on a scaled UAV wing segment. These findings indicate that suitably engineered E-glass composites can be a viable, cost-effective alternative to carbon fiber for impact-resistant UAV wing structures.

Abstract: Drag reduction forms a key area of focus in aerodynamics with a significant emphasis on delaying the laminar to turbulent transition of boundary layers over the wing of aircraft. There is enough evidence to suggest that achieving such transition delays is particularly challenging for backward swept wings with large leading edge sweep angles, which give rise to crossflow and attachment line instabilities, in addition to the Tollmien-Schlichting waves. The sustenance of extended laminar flow regions at high sweep angles has been demonstrated in recent studies, by designing airfoils with specially curated leading edge profiles, which generate pressure distributions that can suppress crossflow. Such airfoils are called Crossflow Attenuating Natural Laminar Flow (CATNLF) airfoils. However, the design of such airfoils is presently restricted to inverse methodologies due to the inability of the conventional geometry parameterization techniques in representing the specialized leading edge profiles of CATNLF airfoils. The aim of this study is to illustrate that a parametric representation of CATNLF airfoils can be realized using Bezier curves, thereby enabling their forward multi-point design using gradient-free Bayesian optimization. The developed design framework in terms of geometry parameterization and optimization formulation is able to deliver airfoils that can sustain natural laminar flow up to around 50% chord length on the upper surface, with a leading edge sweep angle greater than 27 degrees at a Mach number of 0.78 and a Reynolds number of 20 million within a range of lift coefficients Cl = 0.5 ± 0.1, making them a suitable design choice for a medium-range transport aircraft.

Abstract: In this paper a folding wing based on gear meshing deformation mechanism is developed, focusing on structural analysis and further optimization of the folding wing. Compared with existing folding wing concepts, the deformation mode of this wing is easier to manufacture and implement in engineering. A dynamic contact finite element model of gear meshing is established in ABAQUS, achieving the transmission of motion. The meshing simulation on the gear pair and dynamic strength analysis on the gear mechanism is conducted to obtain stress analysis. The results shows that the mechanism meets the strength requirements. Further dynamic numerical simulations are conducted on the outboard wing to determine the hazardous area of the load, indicating that the folding wing meets the strength requirements. At the same time, the analysis is conducted on the displacement at the tip of the outboard wing, indicating that the folding motion is relatively gentle. Finally, based on the stress analysis results, a weight reduction topology design is carried out for the spoke area of the gear and the rib structure of the folding wing using the variable density method. While ensuring strength, the optimal distribution of materials is sought by using as little material as possible, and the model is reconstructed according to the optimization results. The optimization results show that the weight reduction effect is significant.

Abstract: The engine system requirements for different engine cycles significantly influence the design of the mixing head. A literature review of fuel-injection technology for hydro-gen and methane is presented. The literature review aimed to answer proposed questions specific to the liquid rocket engine fuel injector design. The current review methodology accounts for the engine system effect. Thus, a comprehensive literature review of the working principles of startup-staged combustion cycle engines based on original patents is provided. At the end of the review, the research gaps and suggestions for further work are summarised. At high mass flow rate and injection pressure in the supercritical regime (> 50 MPa), experience is limited to the staged combustion cycle developed in Russia and the US. It is necessary to consider a fluid-dynamic heat transfer coupling study for the multi-injection element design in the supercritical state. Cryogenic spray atomisation experiments need to be designed with research significance. It is still needed to study how the similarity of the spray flow field to the combustion performance affects a liquid rocket engine problem. Moreover, scaling stoichiometric mixing theory needs to be expanded to different injector types, such as tri-coaxial and pintle injectors, to validate the correlation between the nonreactive mixing length and flame length.

Abstract: In low-Earth-orbit (LEO) satellite networks, the requirement for intelligent parameter-adjustment strategies has become increasingly critical due to the presence of highly dynamic channel conditions, limited spectrum resources, and complex interference environments. In this paper, a method for optimizing LEO satellite communication links based on deep reinforcement learning (DRL) is proposed. Through the optimization of the transmit power, the modulation and coding scheme (MCS), the beamforming parameters, and the retransmission mechanisms, adaptive link control is achieved in dynamic operational scenarios. A multidimensional state space is constructed, within which the channel state information, the interference environment, and the historical performance metrics are integrated. The spatio-temporal characteristics of the channel are extracted by means of a hybrid neural architecture that incorporates a convolutional neural network (CNN) and a long short-term memory (LSTM) net-work. To effectively accommodate both continuous and discrete action spaces, a hybrid DRL framework that combines proximal policy optimization (PPO) with a deep Q-network (DQN) is employed, thereby enabling cross-layer optimization of the physical-layer and link-layer parameters. The results demonstrate that substantial improvements in throughput, bit error rate (BER), and transmit-power efficiency are achieved under severely time-varying channel conditions, which provides a new idea for resource management and dynamic-environment adaptation in satellite communication systems.

Abstract: Ice accretion along aircraft leading edges, particularly at stagnation line parting strips, remains difficult to remove using conventional electrothermal anti-icing systems. These systems require continuous high-power heating to maintain the stagnation region above the melting point, often exceeding 10–12 kW/m². This study introduces an Ice Cavitation Deicer (ICD) that removes ice through rapid, localized cavitation generated within a thin melt layer formed at the ice–surface interface. In the proposed approach, a short pulse of electric current melts a 1–10 µm interfacial layer and causes a cavitation impulse of approximately 1–10 MPa. This impulse ejects the stagnation line ice in a direction normal to the surface, often against the external airflow, enabling the immediate aerodynamic removal of the remaining ice. Analytical modeling based on the energy conservation principle was used to determine the optimal foil geometry, thermal pulse parameters, thermal stress, and material selection. Experiments with various metallic foils and substrate materials validated the predicted ejection behavior. Compared with conventional thermal anti-icing, the ICD concept reduces power consumption by approximately two orders of magnitude while offering rapid and reliable leading-edge deicing.

Abstract: This work presents the development, modelling, integration, and validation of a flight control system (FCS) designed to convert a piloted ultra-light aircraft (ULM) into a fully autonomous vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV), while maintaining Optionally Piloted Vehicle (OPV) capability. Unlike conventional ULM autopilots focused mainly on stabilization or pilot assistance, the proposed architecture enables full mission-phase autonomy, including take-off, hover, transition, cruise, approach, and landing, and ensures safe coexistence between autonomous and manual control pathways. A high-fidelity simulation framework was developed in MATLAB/Simulink and Simscape, integrating aerodynamic models derived from XFLR5 and VSPAERO, structural and inertia modelling, propulsion and energy-storage dynamics, and the complete cascaded control structure. Hardware-in-the-Loop (HIL) experiments were conducted using a modular test bench featuring a six-degree-of-freedom force–moment balance and an internal-combustion propulsion unit, allowing the injection of realistic vibration signatures into the control loop. Results demonstrate robust tracking of attitude and angular-rate commands under significant perturbations and AHRS measurement noise, indicating the system’s readiness for initial VTOL flight tests and subsequent transition-mode refinement. Overall, the paper details the control architecture, modelling methodology, simulation environment, and preliminary ground-testing efforts supporting advancement toward Technology Readiness Level 6.

Abstract: Commercial supersonic passenger transport has been absent from global aviation for more than two decades, largely due to regulatory, geographic, and economic constraints. While renewed interest in supersonic travel has emerged with advances in aircraft design, there remains a lack of scalable methods for assessing where such operations could be viable. This study evaluates supersonic feasibility at the route level using a data-driven framework that integrates engineering, regulation, and economics. A global dataset comprising 435 city-pair routes was constructed using aircraft performance estimates, great-circle routing, over-water routing fractions, and demand indicators derived from population and gross domestic product data. Routes were labeled as feasible or unfeasible based on domain-informed criteria, and supervised machine-learning models were trained to learn a continuous feasibility score between 0 and 1. A Decision Tree classifier was used to extract interpretable feasibility rules, while an Extreme Gradient Boosting (XGBoost) classifier provided predictive performance. Model behavior was analyzed using SHapley Additive exPlanations (SHAP). The results show that over-water routing fraction is the dominant determinant of feasibility, followed by time savings and great-circle distance, with demand contributing in marginal cases. The framework produces a ranked set of candidate routes as well as a predictive engine for future routes.

Abstract: Traditional reliability engineering paradigms, originally designed to prevent physical component failures, are facing a fundamental crisis when applied to today's soft-ware-intensive and autonomous systems. In critical domains like aerospace, the dom-inant risks no longer stem from the aleatory uncertainty of hardware breakdowns, but from the deep epistemic uncertainty inherent in complex systematic interactions and non-deterministic algorithms. This paper reviews the historical evolution of reliability engineering, tracing the progression through the Statistical, Physics-of-Failure, and Prognostics eras. It argues that while these failure-centric frameworks perfected the management of predictable risks, they are structurally inadequate for the "unknown unknowns" of modern complexity. To address this methodological vacuum, this study advocates for an imperative shift towards a fourth paradigm: the Resilience Era. Grounded in the principles of Safety-II, this approach redefines the engineering objec-tive from simply minimizing failure rates to ensuring mission success and functional endurance under uncertainty. The paper introduces Uncertainty Control (UC) as the strategic successor to Uncertainty Quantification (UQ), proposing that safety must be architected through behavioral constraints rather than prediction alone. Finally, the paper proposes a new professional identity for the practitioner: the system resilience architect, tasked with designing adaptive architectures that ensure safety in an era of incomplete knowledge.

Abstract: Drones have long been explored for supply. While several systems offering small pay-loads in drone delivery have seen operational use, large-scale supply drones have yet to be adopted. A range of setbacks cause this, including technological and operational challenges that hinder their adoption. Here, these challenges are evaluated from a conceptual modelling perspective to forecast their applicability once these barriers are overcome. The study uses technology trend modelling and bibliometric activity map-ping methodologies to predict the applicability of specific technologies that are cur-rently identified as operational challenges. Specifically for supply drones, trends in technological improvements of battery technology and aircraft control are modelled to project effects and focus on landing zone autonomy and powertrain. The prediction also focuses on the current state of hybrid power and higher levels of automation required for landing zone operations. These models are validated through several published case studies of small delivery drones and then applied to assess the feasibility and con-straints of larger supply drones. A case study, conceptual design of a supply drone large enough to move a shipping container, is presented to illustrate the critical technologies required to transition large supply drones from concept to operational reality. Key technologies required for large-scale supply drones have yet to build up a critical mass of research activity, particularly on landing zone autonomy and powertrain. Moreover, additional constraints beyond technological and operational challenges could include limitations in autonomy, certification hurdles, regulatory complexity, and the need for greater social trust and acceptance.

Abstract: The need for simpler, yet accurate and physically sound, methods to predict the lift and pressure distributions over asymmetric delta wings, particularly at high angles of attack with attached shock wave, motivates the development of an alternative approach presented in this paper. By employing a geometric transformation and postulating a functional similarity between linear and nonlinear solutions, a straightforward algebraic technique for pressure estimation is developed. This approach bridges the solution in the central nonuniform flow region to the exact solutions in the uniform flow regions with attached shock waves near the leading edges, in a manner analogous to methods used for supersonic starting flow at high incidence. The method is shown to reproduce established results for both symmetric and yawed delta wings within a limited error. It yields a compact, explicit expression for the normal force coefficient, formulated as a weighted average of the pressure coefficients from the two uniform flow regions. A pathway for extending the approach to the upper surface, where the uniform flow is governed by swept Prandtl-Meyer relations is also outlined. Although classical analytical approaches for delta wings were established decades ago, the proposed method provides a tractable alternative tool for modern fast engineering analysis.

Abstract: Very Low Earth Orbit (VLEO) satellites, operating at altitudes below 450km, provide tremendous potential in the domain of remote sensing. Their proximity to Earth of-fers high resolution, low latency, and rapid revisit rates, allowing continuous moni-toring of dynamic systems and real-time delivery of vertically integrated earth ob-servation products. Nonetheless, the application of VLEO is not yet fully realized due to numerous complexities associated with VLEO satellite development, considering atmospheric drag, short satellite lifetimes, and social, political and legal regulatory fragmentation. This paper reviews the recent technological developments supporting sustainable VLEO operations with regards to aerodynamic satellite design, atomic oxygen barriers, and atmospheric-breathing electric propulsion (ABEP). Furthermore, the paper pro-vides an overview of the identification of regulatory and economic barriers that extort additional costs for VLEO ranging from frequency band allocation and space traffic management to life-cycle cost and uncertain commercial demand opportunities. Nevertheless, the commercial potential of VLEO operations is widely acknowledged, and estimated to lead to an economic turnover in the order of 1.5 B$ by 2030. Learning from the literature and prominent past experiences such as the DISCOVERER and the CORONA program, the study identifies key gaps and proposes a roadmap to sustainable VLEO development. The proposed framework emphasizes modular and serviceable satellite platforms, hy-brid propulsion systems, and globally harmonized governance in space. Ultimately, public-private partnerships and synergies across sectors will determine whether VLEO systems become part of the broader space infrastructure unlocking new capabilities for near-Earth services, environmental monitoring, and commercial innovation at the edge of space.

Abstract: This study introduces an all-fiber optic sensing network based on fiber Bragg grating (FBG) technology for structural health monitoring (SHM) of launch vehicle payload fairings un-der extreme thermo-mechanical conditions. A wavelength–space dual-multiplexing ar-chitecture enables full-field strain and temperature monitoring with minimal sensor de-ployment. Structural deformations are reconstructed from local measurements using the inverse finite element method (iFEM), achieving sub-millimeter accuracy. High-temperature experiments verified that FBG sensors maintain a strain accuracy of 0.8 με at 500 °C, significantly outperforming conventional sensors. Under 15 MPa mechanical loading and 420 °C thermal shock, the fairing structure exhibited no damage propagation. The sensing system captured real-time strain distributions and deformation profiles, con-firming its suitability for aerospace SHM. The combined use of iFEM and FBG enables high-fidelity, large-scale deformation reconstruction, offering a reliable solution for reusa-ble aerospace structures operating in harsh environments.

Abstract: Unmanned Aerial Vehicles (UAVs) are increasingly deployed across diverse domains and many applications demand a high degree of automation, supported by reliable Conflict Detection and Resolution (CD&R) and Collision Avoidance (CA) systems. At the same time, public mistrust, safety and privacy concerns, the presence of uncooperative airspace users, and rising traffic density are driving a shift toward decentralized concepts such as free flight, in which each actor is responsible for its own safe trajectory. This survey reviews CD&R and CA methods with a particular focus on decentralized automation and encounters with noncooperative intruders. It analyzes classical rule-based approaches and their limitations, then examines Machine Learning (ML)–based techniques that aim to improve adaptability in complex environments. Building on recent regulatory discussions, it further considers how requirements for trust, transparency, explainability, and interpretability evolve with the degree of human oversight and autonomy, addressing gaps left by prior surveys.

Abstract:

Precise orbit determination for multi-spacecraft deep-space missions faces challenges including long communication delays, sparse tracking, dynamic model uncertainties, and inefficient data fusion. Presenting a hybrid estimation architecture, this study integrates onboard autonomous navigation with ground-based batch processing of delayed measurements. The framework makes three key contributions: (1) a delay-aware fusion paradigm that dynamically weights space- and ground-based observations according to real-time Earth–Mars latency (4–22 min); (2) a model-informed online calibration framework that jointly estimates and compensates dominant dynamic error sources, reducing model uncertainty by 60%; (3) a lightweight hierarchical architecture that balances accuracy and efficiency for resource-constrained “one-master-multiple-slave” formations. Validated through Tianwen-1 mission-data replay and simulated Mars sample-return scenarios, the method achieves absolute and relative orbit determination accuracies of 14.2 cm and 9.8 cm, respectively—an improvement of >50% over traditional centralized filters and a 30% enhancement over existing federated approaches. It maintains 20.3 cm accuracy during 10-minute ground-link outages and shows robustness to initial errors >1000 m and significant model uncertainties. This study presents a robust framework applicable to future multi-agent deep-space missions such as Mars sample return, asteroid reconnaissance, and cislunar navigation constellations.

Abstract: We study minimum-time heliocentric transfers for a spacecraft propelled by an electric thruster that draws constant electrical power P while continuously varying its exhaust speed (variable Isp). The vehicle is assumed to depart from and arrive on circular heliocentric orbits (i.e., initial and final velocities match the local circular velocity at the respective radii). First, we derive an analytic solution of the one-dimensional, gravity-free brachistochrone and discuss how a finite exhaust-speed ceiling modifies the solution, producing a boost–coast–brake structure. Next, we formulate the full planar Sun-field optimal-control problem, derive two closed-form first integrals, and show that the indirect formulation reduces to a seven-dimensional boundary-value problem. Finally, we present a practical numerical continuation strategy that obtains a coarse feasible endpoint via global optimization and then refines it by homotopy and Powell’s local solver. Numerical examples for a 1GW engine with an initial/dry mass of 3000 t→1000 t demonstrate Earth–Jupiter-class transfers in roughly 200–220 days that commonly exploit a solar Oberth pass. Reproducible code and data are available at the project repository.

Abstract: This paper presents a resilient, multi-layer architecture designed to ensure reliable autonomous operation of single and multiple quadcopters. The architecture leverages the resilient spacecraft executive to hierarchically organize trajectory-planning and flight-control functions, and integrates Simplex architectures at each level to provide safety assurance. A compound subsystem expands robustness by employing multiple candidate algorithms for planning and control, while a supervisory program adapts Simplex behavior based on system states and environmental conditions to enable high-level mission management. The architecture is evaluated in simulations involving environmental uncertainties, including varying wind and obstacles, within a bridge-inspection mission using both single- and multi-quadcopter configurations. Results show that the system maintains safe and effective operation across a wide range of conditions, demonstrating scalability for cooperative multi-agent tasks.

Abstract: Ti-6Al-4V(Ti64), widely used in aerospace structures for its high specific strength and corrosion resistance, is increasingly produced by additive manufacturing (AM) to enhance material efficiency and design flexibility. However, its fatigue performance remains highly variable due to process-induced microstructural heterogeneities and inherent defects. Since aerospace components are designed under damage-tolerant principles, understanding fatigue crack growth (FCG) behavior in AM Ti64 is essential for reliable life prediction. This short review critically examines FCG in Ti64, focusing on the influence of build orientation, processing routes, heat treatment, mean stress, defects, and environmental conditions. These factors, through their effect on the microstructure, govern crack propagation. Achieving consistent and predictable FCG behavior requires standardized test reporting, high-resolution microstructural and defect characterization, and data-driven approaches, that link processing, microstructure, and mechanical response. To complement this mechanistic perspective, a meta-analysis of 67 studies was conducted to assess how FCG research in AM Ti64 is reported. The results showed that only 66 percent of studies included details on manufacturing processes and specimen preparation, and just 68 percent documented feedstock characteristics and material properties, whereas 99 percent reported testing conditions. These gaps highlight the need for more consistent and harmonized reporting. To address this, a reporting benchmark grounded in established testing standards and domain expertise is proposed. Such standardization will enhance reproducibility, enable meaningful data comparisons, and advance data-driven FCG research in AM.