As a type of hi-tech weapon, hypersonic vehicle plays an important strategic role in national security and benefits. It has now become a research hotspot in the field of aerospace, and the competition is becoming increasingly fierce all over the world. Advanced material and structure design is a basic key technology to support the development of hypersonic vehicle. The strength of materials and structures in extremely severe service environments is still a key issue restricting the development of this type of aircraft. This paper reviews the structure strength problems and evolution characteristics in the field of hypersonic vehicles in the past few decades. Combined with the current vehicle model development demand and technology development trend, this paper analyzes the current situation and shortcomings of structure strength technology in supporting the development of hypersonic vehicles and discusses the new requirements, new characteristics and new methods of strength problems in this field in the future. Finally, the future development direction in the field of hypersonic vehicle structure strength is proposed after summarization.

The k-ω Shear Stress Transport （SST） turbulence model， one of the best eddy viscosity models with comprehensive performance， has been widely used in recent years. However， with the increase of problem complexity and simulation accuracy requirements， the standard SST turbulence model shows clear limitations in certain aspects， eliciting extensive improvement research. This paper reviews the improvement research of the SST model from six aspects： rotation/curvature effect， compressibility effect， shock wave unsteadiness effect， effect of anisotropy Reynolds stress， effect of stress-strain deviation， and laminar/turbulent transition effect. Meanwhile， it also briefly introduces the model improvement based on the data-driven technology in recent years， sorts out the ideas and development trends of various improvement research， expounds their applicability and limitations， and analyzes the reasons and problems affecting the improvement effect. Finally， some suggestions for future work are given.

Gas turbine engine is a comprehensive embodiment of the level of national science, technology and industry. Fault diagnosis is an important guarantee for its safe and reliable operation and an essential indicator of engine advancement. However, due to the complicated structure, highly integrated system, harsh service environment, variable mission profiles, the constraints of limited online testing conditions, and the poor supportability of diagnostic information acquisition, the fault diagnosis for aeroengine faces multiple challenges. In this paper, the research status in China and abroad is firstly reviewed and analyzed from three aspects: gas path analysis and performance evaluation, mechanical fault diagnosis and information fusion. Then, the exciting key problems and challenges in the current research are pointed out. Finally, the future development trends are discussed.

Avian radar has become an important bird situation observation tool in airport bird strike avoidance. The origin of avian radar technology is first introduced, followed by analysis of the target characteristics of flying birds in terms of the target echo amplitude, flight speed, flight height, trajectory characteristics and micro-Doppler characteristics. Four typical airport avian radar systems, including Merlin radar, Accipiter radar, Robin radar and Aveillant radar, and the research status of the domestic avian radar technology are then introduced. Key radar technologies such as antenna, radar waveform, target detection and tracking, target recognition and classification are analyzed, and the performance of typical avian radar systems compared. In addition, the applications of avian radar are discussed with respect to the fusion of radar and photoelectric technologies, the linkage of bird detection and repellent, and the bird information analysis. Conclusions are finally drawn and prospects are made.

The rapid development of the next generation of aerospace technology has imposed more and more stringent requirements for such structural performance as the ultra-strong load-bearing， extreme heat-proof， ultra-precision and ultra-lightweight. Therefore， how to design and fabricate high-performance， lightweight， and ultra-precise aerospace thin-walled structures has become a common concern in the field of advanced material and structural design and manufacturing. This paper reviews the main achievements of high-performance design and manufacture of thin-walled components and their aerospace applications in recent years， focusing on the scientific issues including the mapping law between multi-scale structures and structural performance， the composed manufacturing principle of multi-material and multi-scale structures， and the interaction mechanism between material organization evolution and structural deformation. Moreover， the manufacturing process constraints in structural optimization， the influence of additive manufacturing process parameters on the structural optimization， the material-structure integrated design method of high-performance structures and its application in aerospace structures are discussed. The development prospects and applications of the material-structure integrated design and manufacturing methods of typical aerospace thin-walled structures in the future are also prospected， which can provide references for future related research and aerospace applications.

Benefitting from the superiorities brought by the organic fusion of different materials, high-performance composites are considered as an effective approach to achieving light-weight design, multi-functionality and intelligentization of aviation aircraft. However, the high anisotropy and multi-scale structural properties of the composites also produce significant problems and challenges for structural design, fabrication and characterization. The application and development of high-performance composite materials in aircraft is a multi-disciplinary problem involving, material science, mechanical engineering and control technology. Focusing on several related fundamental mechanical problems, this paper mainly presents a critical review on the recent research progress in mechanical design and property evaluation, functional design and manufacturing mechanics of aircraft composite structures. An outlook for the research directions in aircraft composite structures is provided in the final part.

Intelligent decision-making for aircraft air combat is a research hotspot of military powers in the world today. To solve the problem of Unmanned Aerial Vehicle （UAV） maneuvering decision-making in the close-range air combat game， an autonomous decision-making model based on deep reinforcement learning is proposed， where a reward function comprehensively considering the attack angle advantage， speed advantage， altitude advantage and distance advantage is adopted and improved. The improved reward function avoids the problem that the agent is induced to fall to the ground by the enemy aircraft， and can effectively guide the agent to converge to the optimal solution. Aiming at the problem of slow convergence caused by random sampling in reinforcement learning， we design a value-based prioritization method for experience pool samples. Under the premise of ensuring the algorithm convergence， the convergence speed of the algorithm is significantly accelerated. The decision-making model is verified based on the human-machine confrontation simulation platform， and the results show that the model can suppress the expert system and the driver in the process of close air combat.

TDOA/FDOA localization is an important wireless positioning mechanism for moving emitters， and its location accuracy is greatly affected by measurement errors of TDOA/FDOA and prior measurement errors of sensor models （including sensor position and velocity）. To improve the localization performance under the condition of high-level measurement errors， a TDOA/FDOA cooperative localization method for multiple disjoint sources is proposed based on weighted multidimensional scaling analysis in this paper. The proposed method consists of two calculation stages： Stage-a and Stage-b. Specifically， in Stage-a， two groups of scalar product matrices in multidimensional scaling analysis are employed to form the positioning relationship， which is further used to yield the solutions for the locations of multiple disjoint sources and sensors by constructing a weighting matrix. In Stage-b， a constrained minimization model is established based on the intermediate variables introduced in multidimensional scaling analysis to determine the estimation errors in Stage-a. By solving this optimization problem， the expression for the localization errors in Stage-a are obtained， so as to refine the position and velocity estimates of the multiple disjoint sources as well as the sensors. In addition， the first-order error analysis is employed to prove that the proposed method can asymptotically reach the Cramér-Rao Bound （CRB） accuracy. Simulation results show that the new method outperforms the existing TDOA/FDOA positioning methods.

The Variable Camber Wing(VCW) remains a research hot-spot as it aims to ensure that aircraft acquire optimal aerodynamic efficiency in various flight conditions. The benefits brought by VCWs are firstly presented, and the demands of VCWs from different types of aircraft are classified and thoroughly described. The developing process of VCWs in the past decades are then reviewed in terms of the leading edge and the trailing edge, respectively, and the current major obstacles in application are listed. Further research directions are finally suggested.

The engineering advancements during the last two decades have presented opportunities as well as challenges for the Engine Health Management (EHM) system development of civil aero-engines. This R&D review provides an in-depth discussion on EHM needs, gaps and potential solutions/future R&D development directions, focusing on the "up-stream" EHM development modules: Engine gas path diagnostics and prognostics, mechanical diagnostics and prognostics, FADEC diagnostics and prognostics. Results shows the Unscented Kalman Filter (UKF) method and deep-learning neural networks have shown promises on improving the engine gas path diagnostics accuracy; composite fans have found widespread applications in turbo-fan engines; powder metallurgy has seen more and more applications on fabricating aero-engine parts with complex shapes; the accuracies of metal particle sensing technologies have witnessed significant improvements, with technology readiness level matching the aero-engine needs, and paved the way for fusion diagnostics with vibration signal. The result also show that electrification and intelligentization trends of FADEC system presents new challenges for the diagnostics of the traditionally centralized control architecture.

Distributed hybrid electric propulsion system has great potential and advantage in development of general electric aviation. By the optimization of secondary power system, hybrid electric technology can not only heighten the utilization efficiency of energy, but also satisfied the distributed arrangement of power system for higher propulsive efficiency. The paper firstly summarized the current major types of electric aircraft, reviewed the history background of distributed electric propulsion aircraft. Then, the research status of distributed hybrid electric propulsion aircraft technology is summarized, this part mainly discussed the distributed layout technology of propulsion system, type-selection design of hybrid electric propulsion system, modeling and energy management of hybrid electric propulsion system, and so on. The key technologies of distributed hybrid electric propulsion at home and abroad are discussed fully. Eventually, combined with the research of the team, the difficult point problems and solutions of distributed hybrid electric propulsion aircraft are discussed in detail, including dynamic management strategy of energy based on complex system optimization control, optimal energy distribution prediction model driven by historical big data, and principle prototype designing of distributed hybrid electric propulsion system. The main content of this paper clarify the design thoughts and analysis method for distributed hybrid electric propulsion system and energy arrangement, which can provide references for the research of electric propulsion aircraft technology.

UAV aerial images have more complex backgrounds and a large number of dense small targets compared with natural scene images, which impose higher requirements on the detection network. On the premise of ensuring real-time object detection, a YOLOv5-based UAV real-time dense small object detection algorithm is proposed for the problem of low accuracy of dense small object detection in UAV view. First, combining Spatial Attention Module (SAM) with Channel Attention Module (CAM), the fully connected layer after feature compression in CAM is improved to reduce the computational effort. In addition, the connection structure of CAM and SAM is changed to improve the spatial dimensional feature capture capability. In summary, a Spatial-Channel Attention Module (SCAM) is proposed to improve the model's attention to the aggregated regions of small targets in the feature map; secondly, an SCAM- based Attentional Feature Fusion module (SC-AFF) is proposed to enhance the feature fusion efficiency of small targets by adaptively assigning attentional weights according to feature maps of different scales; finally, a backbone network is introduced in the Transformer in the backbone network, and use the SC-AFF to improve the feature fusion at the original residual connections to better capture global information and rich contextual information, and improve the feature extraction capability of dense small targets in complex backgrounds. Experiments are conducted on the VisDrone2021 dataset. The effects of different network scale parameters and different input resolutions on the detection accuracy and speed of YOLOv5 are first investigated. The analysis concludes that YOLOv5s is more suitable to be used as a benchmark model for UAV real-time object detection. Under the benchmark of YOLOv5s, the improved model improves mAP50 by 6.4% and mAP75 by 5.8%, and the FPS for high-resolution images can reach 46. The mAP50 of the model trained at an input resolution of 1504×1504 can reach 54.5%, which is 11.5% better than that of YOLOv4. The accuracy is improved while the detection speed FPS remains at 46, which is more suitable for real-time UAV object detection in dense small target scenarios.

The electrification degree of airborne equipment continues to increase with the development of science and technology. Owning to this, failure in aircraft power system is posing an increasing threat to flight safety, which granted necessity to fast and accurate health state assessment. The commonly used data-driven fault diagnosis method cannot make use of expert knowledge. Meanwhile, the result of data-driven method is lack of interpretability, and therefore, limits its application in real practice. Knowledge graph has the ability to normalize the storage of such unstructured data as expert knowledge and use it for diagnosis. Moreover, knowledge graph can utilize the unstructured knowledge and supply a reasonable explanation for the cause of the failure. However, in the field of fault diagnosis, there are still few studies on the application of knowledge graph technology. In this article, a knowledge graph construction and application technology for aircraft power system fault diagnosis is proposed. First, ontology of the knowledge graph, which specifies the entity and relation types in the knowledge graph, is constructed based on the priori expert knowledge. Then, Bi-Directional Long Short-Term Memory (Bi-LSTM) method is trained with BMEO-tagged corpus and utilized to extract entities from the unstructured texts. After that, an attention-based Bi-LSTM algorithm is trained with relation-tagged corpus and then utilized to realize relation extraction. Finally, the knowledge graph for aircraft power system fault diagnosis is constructed based on the extracted entities and relations. A fault isolation manual of aircraft power system is used as raw corpus data in the case study to verify the effectiveness of the proposed method by the indicators of precision and recall. Based on the knowledge graph, intelligent searching, recommending and Q & A are realized, which strongly support the application prospect of knowledge graph in the field of fault diagnosis.

Lightweight is a substantial theme in the research and development of aerospace and aeronautical equipment due to its decisive impact on the comprehensive performance and operational efficiency of the equipment. Over the past decades， a handful of innovative optimization design approaches， emerging high-performance materials， and revolutionary manufacturing technologies have been uninterruptedly developed， and the level of lightweighting in aerospace and aeronautical equipment has been significantly advanced. However， the increasing demands for comprehensive performance and multifunctionality of the next generation of equipment present serious challenges to existing lightweight design and manufacturing technologies. Therefore， with a particular emphasis on the layout design， electromechanical system design， materials and structures， high-performance manufacturing and assembly， this paper analyzes the posed challenges and future perspectives.

Based on a comprehensive coverage of the civil aero-Engine Health Management (EHM) needs and goals, this research and development review first analyzes the current status quo & industry trends from the perspectives of the full blown Condition Based Maintenance Plus (CBM+) process, then addresses the challenges and gaps, and points out the critical paths for the future EHM research and development. Furthermore, this research and development review provides in-depth discussions on needs, gaps, and potential EHM solutions/future developments of the three "down-stream" EHM development modules: off-board comprehensive diagnostics, engine life management, intelligent condition based mro (maintenance, repair, overhaul).

The superconducting machine has prospects of a wide range of applications in aviation electric propulsion due to its advantages such as small size， high power density， and high efficiency. The characteristics and current situation of the superconducting pure/hybrid electric drive systems are compared， showing the importance of the superconducting machine for high power aviation electric propulsion. In view of different requirements for motors and generators for the superconducting electric drive system for high power aviation electric propulsion， the operating principles and structural topologies of those prototypes of High Temperature Superconducting （HTS） machines studied in the past are reviewed and classified， and the advantages and disadvantages are summarized and analyzed. On this basis， the key technologies of superconducting machine are outlined in terms of superconducting technology， AC superconducting armature， rotor technology， cryogenic technology and insulation technology. Under the background of aviation electrification， the progress in the application of superconducting electric drive system in aviation electric propulsion is outlined， and future development of superconducting electric aviation is also discussed.

Next-generation Supersonic Transport Aircraft （STA） has become one of the main future directions for civil aviation transport. Compared with subsonic civil aircraft， STA involves a series of technical problems such as sonic boom and is confronted with more strict performance indexes， imposing higher requirements for the conceptual aerodynamic configuration design. This paper classifies the existing supersonic civil aircraft configurations in the world into three generations according to the design strategy and the main technical features. The first-generation configurations mainly adopt a delta wing/ double-delta wing platform to achieve supersonic civil flight and balance both high and low speed performance. The second-generation configurations take the low-boom and low-drag performance into consideration and employ the highly-swept arrow-wing tailless layout， while the third-generation focuses more on the multi-disciplinary comprehensive performance and the technical feasibility. Almost all these configurations adopt the T-tail or V-tail layout and the engine nacelle knapsack or tail crane layout. The technical bottlenecks and difficulties of the new generation STA conceptual-aerodynamic configuration design are then presented. The progress and state of the art of the conceptual design technology， low-boom design technology， supersonic drag reduction technology， and airframe-propulsion integrated design technology are reviewed. Finally， the development trend of a new-generation STA configuration is discussed， stressing some of the key scientific and technical issues to be broken through. Supersonic business jets or small and medium class STA will be the priority in the near future， with technical features approximating those of the third-generation configurations. Comprehensive performance and engineering realizability of factors such as sonic boom， drag reduction， airframe-propulsion integration， aeroelasticity， and man-machine efficacy should be the mainly concern in future research.

Tianwen-1 is the first mission in the world to achieve the three goals of Mars orbiting, landing and roving in one mission, and has made some key-technology breakthroughs. The mission objectives and flight progress are introduced, and eight kinds of innovation achievements and the main technical breakthroughs are comprehensively summarized in this paper. Specifically, the key technologies include the overall design of Mars orbiting, landing and roving objectives strongly coupled, multi-trajectory launch of Earth escape orbit, interplanetary flight and Mars capture, Mars enter, descent and landing, solutions adaptive to Martian harsh environment, 400-million-kilometer communication, advanced payloads of remote sensing and patrol detection, and Mars environmental modeling and ground validation. The complete success of the mission has made China become one of the advanced countries in the field of deep space exploration.

SensorCraft is an early warning and surveillance and information synthesis aircraft proposed by the Air Force Research Laboratory， with high ceiling and long endurance. It adopts the platform-payload integration technology， with the dual features of the aircraft and sensor. Coupling of multiple elements between platform and payload means that the overall layout design is different from that of the traditional Intelligence， Surveillance and Reconnaissance （ISR） vehicle. Flight conditions and performance indexes bring new challenges to the aerodynamic design. Aeroelastic problem of large aspect ratio flexible wing not only worsens flight performance， but also leads to loss of electromagnetic performance of wing conformal antenna. This paper summarizes the technical characteristics of SensorCraft， expounds the development history of the United States SensorCraft system from two aspects of the flight platform and conformal antenna. From the perspective of technical characteristics， key technologies supporting SensorCraft are sorted out， such as integrated layout design， laminar drag reduction， gust alleviation， conformal antenna design， deformation measurement & reconstruction， and electromagnetic performance compensation. Relevant applications are introduced. The development trend of this aircraft is also discussed in terms of the flight ability， stealth ability， perception ability and coordination ability of the aircraft， so as to provide reference for the new ISR aircraft.

The development of reusable launch vehicles is the persistent pursuit of aerospace industry. Although the first flight of the fully reusable SpaceX two-stage heavy-lift starship was successfully launched， the starship was ultimately self-destructed due to the loss of control in the subsequent flight. After reviewing evolutionary design and the first flight experience of the heavy-lift starship， this paper analyzed the application modes of the heavy-lift starship based on the overall scheme， identified the key technologies involved， and summarized its impact on aerospace industry. Finally， the enlightenment and suggestions of the heavy-lift starship’s achievements to China’s aerospace industry are provided.