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In order to avoid the hard landing on the uneven ground, several robotic landing gears of the rotorcraft are designed. In previous studies, most literature focuses on the control methods of the robotic landing gears. There has been very little research on the dynamic model of the rotorcraft with the robotic landing gears in the landing process. In this work, based on the Lagrangian formulation, the dynamic model of the rotorcraft considering different parameters in the landing process is derived, where the angle of the slope of the uneven ground and the angle of the attack of the rotorcraft are considered. Then an approach is presented to determine the bounds of the dynamic response of the rotorcraft with uncertainties parameters. The results of numerical examples show that in order to maintain the safety, the robotic landing gear of the rotorcraft would be controlled to adjust the condition of the ground, while the initial velocities are restricted to be less than certain value; the large deviations of the landing parameters would may resulted in an overload of the rotorcraft.

In order to investigate the landing process of a vertical landing reusable vehicle, a dynamic model with a complex nonlinear dissipative element is established based on the discrete impulse step approach, which includes a three-dimensional multi-impact model considering friction and material compliance, and a multistage aluminum honeycomb theoretical model. The normal two-stiffness spring model is adopted in the foot–ground impact model, two motion patterns (stick and slip) are considered on the tangential plane and the structural changes caused by buffering behavior are included, and the energy conversion during the impact follows the law of conservation of energy. The state transition method is used to solve the dynamic stability convergence problem of the vehicle under the coupling effect of impact and buffering deformation in the primary impulse space. Landing experiments on a scaled physical reusable vehicle prototype are conducted to demonstrate that the theoretical results exhibit good agreement with the experimental data.

As Urban Air Mobility (UAM) moves toward implementation, managing high-density, high-volume flights in urban airspaces becomes increasingly critical. In such environments, the design of vertiport airspace structures plays a key role in determining how many UAVs can operate safely and efficiently within a specific airspace. Existing studies have not fully explored the complex interdependencies between airspace structure parameters and fleet operation capacity, particularly regarding how various structural components and their configurations affect UAV fleet performance. This paper addresses these gaps by proposing a multi-layered funnel-shaped airspace structure for vertiports, along with an adjustable parameter model to assess factors affecting landing capacity. The proposed design includes the assembly layer, upper layer, lower layer, and approach point, forming the basis for fleet operations, divided into three phases: arrival, approach, and landing. By modeling fleet operations with various constraints and time-based algorithms, simulations have been conducted to analyze the impact of changing airspace structure parametric dimensions on UAV fleet operation capacity. The results reveal that fleet capacity is closely influenced by two limitations: the distance traveled in each phase and the availability of holding points at each layer. These findings provide valuable insights and contribute to future airspace design efforts for UAM vertiports.

Mars' surface is characterized by a weathered layer of regolith and exposed rock exposures that are the results of long‐term geological processes. The Mars Rover Penetrating Radar (RoPeR) on board the Zhurong rover of China's first Mars mission (Tianwen‐1) has been investigating the fine structure and dielectric properties of the martian regolith in the southern Utopia Planitia. The permittivity of the regolith within 5 m of the landing zone is 3.6−2.0+3.1${3.6}_{-2.0}^{+3.1}$ , and the average loss tangent is 0.0174−0.0053+0.0053${0.0174}_{-0.0053}^{+0.0053}$ . The high lossy parameter suggests the possible cause for the missing subsurface reflectors in the landing region detected by either in‐situ radar or orbiter radars. The permittivity distribution map has been derived to show permittivity varying with depth and location. The high dispersion of both permittivity and loss tangent values along the traverse path indicates relatively heterogeneous material distribution on the landing site compared to an airless body such as the Moon. Plain Language Summary A layer of regolith covers the surface of Mars, which is the result of geologic processes that occurred over millions to billions of years. Compared to the observations from satellites, the Zhurong rover of China's first Mars mission (Tianwen‐1) had a closer look at the properties of the regolith layer in the explored region within southern Utopia Planitia. There is evidence that the exposed materials might be related to aqueous activities. Local landforms on the surface suggest the possible presence of buried volatiles, like water ice. The radar instrument (RoPeR) on board the rover can expose subsurface structures and the dielectric properties of the regolith layer at high‐resolution, to assess their composition. The loss tangent results suggest that water ice is not the main component of the local martian regolith at some depth. The scattering distribution of radar profile along the traveling path and heterogeneous subsurface features show more diverse surface processes and weaker space weathering effects on Mars than those on the airless Moon. Key Points The dielectric properties of martian regolith at the Tianwen‐1 landing site suggest that water ice is not the dominant component The radar image and permittivity and loss tangent distribution maps show a high heterogeneity of subsurface materials Compared to the lunar regolith, the martian regolith shows more diverse surface processes and weaker space weathering effects

Existing approaches to constrained dynamic programming are limited to formulations where the constraints share the same additive structure of the objective function (that is, they can be represented as an expectation of the summation of one-stage costs). As such, these formulations cannot handle joint probabilistic (chance) constraints, whose structure is not additive. To bridge this gap, this paper presents a novel algorithmic approach for joint chance-constrained dynamic programming problems, where the probability of failure to satisfy given state constraints is explicitly bounded. Our approach is to (conservatively) reformulate a joint chance constraint as a constraint on the expectation of a summation of indicator random variables, which can be incorporated into the cost function by considering a dual formulation of the optimization problem. As a result, the primal variables can be optimized by standard dynamic programming, while the dual variable is optimized by a root-finding algorithm that converges exponentially. Error bounds on the primal and dual objective values are rigorously derived. We demonstrate algorithm effectiveness on three optimal control problems, namely a path planning problem, a Mars entry, descent and landing problem, and a Lunar landing problem. All Mars simulations are conducted using real terrain data of Mars, with four million discrete states at each time step. The numerical experiments are used to validate our theoretical and heuristic arguments that the proposed algorithm is both (i) computationally efficient, i.e., capable of handling real-world problems, and (ii) near-optimal, i.e., its degree of conservatism is very low.

It is of great significance to apply the object detection methods to automatically detect boulders from planetary images and analyze their distribution. This contributes to the selection of candidate landing sites and the understanding of the geological processes. This paper improves the state-of-the-art object detection method of YOLOv5 with attention mechanism and designs a pyramid based approach to detect boulders from planetary images. A new feature fusion layer has been designed to capture more shallow features of the small boulders. The attention modules implemented by combining the convolutional block attention module (CBAM) and efficient channel attention network (ECA-Net) are also added into YOLOv5 to highlight the information that contribute to boulder detection. Based on the Pascal Visual Object Classes 2007 (VOC2007) dataset which is widely used for object detection evaluations and the boulder dataset that we constructed from the images of Bennu asteroid, the evaluation results have shown that the improvements have increased the performance of YOLOv5 by 3.4% in precision. With the improved YOLOv5 detection method, the pyramid based approach extracts several layers of images with different resolutions from the large planetary images and detects boulders of different scales from different layers. We have also applied the proposed approach to detect the boulders on Bennu asteroid. The distribution of the boulders on Bennu asteroid has been analyzed and presented.

300 M ultra-high-strength steel (UHSS) is widely used to produce landing gear components for aircraft. The conventional manufacturing route for these components involves extensive machining and significant material wastage. Here, the application of wire-based gas metal arc additive manufacturing to produce 300 M UHSS parts was investigated. In particular, the influence of torch shielding atmosphere on the process stability and material performance of 300 M UHSS was investigated. The shielding gases used for comparison are pure Ar, Ar with 2.5% CO2, Ar with 8% CO2, Ar with 20% CO2, and Ar with 2% CO2 and 38% He. It was found that the arc length decreased, the transfer mode changed from spray to droplet mode, and spattering became more severe as the CO2 proportion increased. Additionally, replacing Ar with He led to a broader arc core, and a slightly shorter arc length and maintained a spray transfer, which decreased spatter. The wall surface roughness followed the trend in spatter, becoming worse with the increasing CO2 proportion, and better with He addition. Adding CO2 and He in pure Ar significantly increased the bead and wall width. The microstructure and mechanical properties exhibited a strong location dependence in the as-built state, with fresh martensite and higher strength in the top region, and tempered martensite and better ductility in the reheated bulk. Generally, torch shielding gas composition appeared to have no significant effect on the microstructure evolution. This study provides a reference for the subsequent application of gas metal arc additive manufacturing to aircraft landing gear mass production to achieve a high deposition rate and process stability simultaneously.

To realize automatic wire arc additive manufacturing (WAAM) of a large aviation die with a complex gradient structure, a new contour-parallel path generation strategy was proposed and practically applied. First, the planar curve was defined as a vertical slice of a higher-dimensional surface and a partial differential equation describing boundary evolution was derived to calculate the surface. The improved Finite Element Method (FEM) and Finite Difference Method (FDM) were used to solve this partial differential equation. Second, a cross section of a large aviation die was used to test the path-generation algorithms. The results show that FEM has a faster solving speed than FDM under the same solving accuracy because the solving domain of FEM mesh was greatly reduced and the boundary mesh could be refined. Third, the die was divided into three layers: base layer, transition layer (Fe-based material) and strengthening layer (Co-based material) according to the difference of the temperature and stress field, and corresponding WAAM process parameters has been discussed. The optimum welding parameters are obtained as follows: voltage is 28 V, wire feeding speed is 8000 mm/min and welding speed is 450 mm/min. Finally, the path generation strategy was practically applied to the remanufacture of the large aircraft landing gear die with a three-layer structure. The application test on aircraft landing gear dies justified the effectiveness of the algorithms and strategy proposed in this paper, which significantly improved the efficiency of the WAAM process and the service life of large aviation dies with complex gradient structures. The microstructure of the fusion zone shows that the base metal and welding material can be fully integrated into the welding process.

Monoclonal Antibodies (mAbs) are being used in the treatment of both malignant and non-malignant diseases and whilst highly effective, certain products have very short expiry times. Clinical deterioration and supply chain disruption can often lead to wastage and there is a need to reduce this by improving efficiency in logistics practices between manufacturing sites and administration locations. This study aimed to investigate the influence of drone flight on the stability of cancer medicines. Clinically expired, premanufactured monoclonal antibodies (mAbs) were investigated, contained inside instrumented Versapaks, and flown in a Skylift (Mugin) V50 vertical take-off and landing drone through seven phases of flight, (take-off, hover, transition, cruise, transition, hover, and landing). Storage specifications (2–8°C) were met, and any vibrations emanating from the drone and transmitted through the packaging during flight were monitored using accelerometers. Vibration occurred largely above 44 Hz which was consistent with rotor speeds during operation and was significantly greater in amplitude during transition than in forward flight or in hover. Bench experiments validated assurance practices, exploring the edge-of-quality failure by applying extremes of rotational vibration to the mAbs. Aggregation and fragmentation represented a loss of quality in the mAbs and would pose a risk to patient safety. No significant difference was identified in the aggregation and fragmentation of all flown mAbs samples, indicating structural integrity. Flown mAbs in their infusion bags had similar particle sizes compared to controls, (Bevacizumab 11.8±0.17 nm vs. 11.6±0.05 nm, Trastuzumab 11.2±0.05 nm vs. 11.3±0.13 nm, Rituximab 11.4±0.27 nm vs. 11.5±0.05 nm) and aggregate content (Bevacizumab 1.25±0.03% vs 1.32±0.02% p = 0.11, Trastuzumab 0.15±0.06% vs. 0.16±0.06% p = 0.75, Rituximab 0.11±0.02% vs. 0.11±0.01% p = 0.73). The quality of the three mAbs was assured, suggesting that the V50 drone did not induce sufficient levels of vibration to adversely affect their quality.

This review paper explores the transformative potential of polymer composites and adhesives in reducing the weight of aircraft landing gear, thereby improving fuel efficiency and lowering emissions. The replacement of conventional metallic materials and mechanical fastenings with advanced thermoset/thermoplastic composites and adhesives can significantly enhance durability and performance in demanding operational environments. Unlike traditional fastening methods, the structural adhesives eliminate the weight penalties associated with mechanical fasteners, offering a lighter and more reliable solution that meets the rigorous demands of modern aerospace engineering. Furthermore, the review highlights a variety of manufacturing techniques and innovative materials, including bio-based polymers, self-healing materials, noobed composites, helicoid composites, and hybrid composites. The use of thermosets and vitrimers in adhesive bonding are presented, illustrating their ability to create robust and durable joints that enhance the structural integrity of landing gear systems. The paper also addresses current challenges, including recycling limitations and high material costs. Sustainability considerations, including the integration of self-healing materials, structural health monitoring systems, and circular economy principles, are discussed as essential for aligning the aerospace sector with global climate goals.