Overload changes the internal ballistics of the motor and the erosion of the thermal protection structure, which increases the coupling degree between engine design and flight trajectory design. Conventional solid rocket overall-motor discrete design is difficult to fully consider this coupling relationship. By studying the coupling relationship between internal ballistics, external ballistics and thermal protection structure, an internal ballistics model and a thermal protection structure model considering flight overload are formed. An integrated simulation method based on internal ballistic model, external ballistics model and thermal protection structure model is established to achieve accurate prediction of internal, external ballistics and thermal protection structure erosion under overload. The calculation results show that under overload, the pressure of the motor increases, the altitude and the local flight path angle of the shutdown point increases, while the flight speed remains basically unchanged. The total mass of the thermal protection structure increases and the thermal protection structure thickness of the nozzle changes, requiring strengthened thermal protection. The integrated simulation correctly predicts the changes of internal and external ballistics under overload, laying the foundation for the joint design of internal ballistics, external ballistics and thermal protection structure, which can improve the integration degree of solid rocket overall-motor design.

In order to respond to the booming development of the commercial satellite launch service market, while effectively utilizing the launching capacity of domestic satellite launch missions and the available envelope space within the payload fairing, and to provide more cost-effective launch services for satellite users, the Long March-2D launch vehicle has developed a main satellite-disk mounting configuration and a tandem-parallel-side hybrid configuration for micro satellite piggyback and multi-satellite rideshare launch missions. This has been applied in the launch missions of the Chinese Hα Solar Explorer (CHASE) and Qilu-2/3 satellites. The feasibility and efficiency of the configuration layout design have been validated through flight tests, achieving effective integration and flexible deployment of satellites with different installation methods. As a mature liquid launch vehicle of conventional propellant, the application of rideshare mode further enhances the mission adaptability of the Long March-2D launch vehicle and can reduce the launch cost of a single satellite.

In order to study the locking-swing phenomenon and swing suppression method during the pyrotechnic driving-locking process of aerocraft door, an explicit dynamic finite element simulation is conducted for an aircraft door opening-locking mechanism driven by a pyrotechnic actuator. The pyrotechnic driving-locking process of the mechanism is simulated in stages and verified compared with the pyrotechnic driving test. The locking-swing phenomenon and mechanism of the door are revealed, and swing suppression method is proposed. The research shows that the simulation method is effective, reproducing the experimental locking-swing phenomenon, and the swing angle is basically consistent with high-speed photography results. A single-freedom torsional vibration model can be used to estimate the swing characteristics of the door. Increasing the stiffness of the actuator or supported structure, or enhancing the door goose neck, has limited effect on swing suppression. Weakening the door goose neck, making it under plastic deformation during door swing, can effectively suppress the swing angle, and meet the demand for pyrotechnic opening of the door in emergency situations.

With the rapid development of technology, digital technology has become a key force driving innovation and development in various industries. Based on extensive research on the current state of digital applications in the aerospace industry both domestically and internationally, this research focuses on summarizing the achievements and experiences of the implementation of digital technology in the engineering development of the SD-3 commercial rocket. The aim is to delve into the current application status of digital technology in the commercial space industry and through typical case studies to analyze its specific implementation strategies, and to provide valuable references and insights for innovation in related fields.

In the process of rocket engine development, the test work is very important, and the main result of the test is a large number of data measured in the test, so the measurement is very important. The rocket engine has a harsh working environment, high test cost, high test risk, many measuring points, high precision and large scale, and requires wide measuring range and frequency to ensure high accuracy of steady-state parameter measurement and no distortion of transient process measurement. Therefore, special requirements are also proposed for the test system. In order to meet the new requirements of rocket engine test, a digital filter is proposed for optimizing the performance of rocket engine test system, which can optimize the dynamic characteristics of the test system on the basis of not changing the original equipment hardware, and meet the requirements of high accuracy of steady-state parameters an no distortion of transient parameters. The experimental results show that the proposed method can obviously improve the performance of rocket engine test system.

Satellite Internet is becoming the new battlefield of global competition. With the development of Chinese satellite network and G60 satellite chain, there is a huge market space for commercial launch of launch vehicles. Under the commercial application, the design, production and launch of Chinese launch vehicle show the trend from fixed launch site, customized research and months of preparation time to random launch site, mass production and several days of preparation time. A heterogeneous network and SDN management based wireless test and launch control system architecture universal for land and sea is proposed, and the integrated design of mobile cabin based test and launch control system is presented. Aiming at the requirements of rapid response, economic efficiency, high reliability and strong environmental adaptability of commercial aerospace, a fast workflow method based on system decoupling, test integration and automatic interpretation is proposed, and a system integration method based on assisting business with commercial general hardware procurement and special software development, improvement of system reliability replacing equipment reliability and ground integrated protection replacing individual adaptation is proposed to achieve a balance between economy and reliability. On this basis, the trend of test and launch technology is introduced from five aspects which are the integration of vehicle functions and ground functions, the test and launch technology with remote assistance, low-cost test and launch mode, test and launch control for recyclable rocket, and application of advanced technology

To address the issues of penetration and precision attacking for air-to-air missiles, an analytical solution for the miss distance of a non-zero-order guidance system is derived. The solution is then extended to advanced guidance laws beyond proportional navigation guidance. Based on these results, the effectiveness of evasion under different maneuvering strategies is analyzed which theoretically explaining the typical characteristics of miss distances in step and serpentine maneuvers and factors influencing the optimal maneuvering strategy are studied. Through reasonable adjustment of maneuver timing and direction, the effectiveness of evasion is improved. Furthermore, considering the integration of penetration and attacking through intelligent guidance laws, an adaptive-stepsize sparsified sampling prior model theory infusion remedial training agent learning (ASTRAL) is introduced. Simulation results show that the missile agent trained with the ASTRAL can effectively evade defender while maintaining its attacking capability during penetration. In addition, the generated guidance law demonstrates good engineering feasibility.

To ensure the reliability of dynamic seal performance of low temperature valve in liquid rocket engine, the sealing pressure and performance of a new type of labyrinth packing dynamic seal structure are simulated and tested. Firstly, the structure of traditional packing dynamic seal is optimized, and a new PTFE-Graphite-Metal labyrinth composite seal is designed. Then, based on the thermal stress coupling method, the influence of the working condition on the dynamic sealing performance is analyzed, and two empirical models for PTFE and Graphite are proposed to represent the dependence of contact stress on both the loading pressure and temperature. Finally, the sealing performance of the new labyrinth dynamic seal is tested at room and low temperature. The results show that the new labyrinth dynamic seal can achieve good sealing performance at room and low temperature, which is consistent with the simulation results.

The intelligent upgrade of the aircraft has put forward new requirements for guidance capabilities, and traditional algorithms perform poorly in tracking spatial three-dimensional trajectories under biased conditions. An aircraft trajectory tracking guidance method is designed based on the TD3 reinforcement learning algorithm. Through the action space in the form of deviation, the penalty term in the reward function and the guidance of the rate of change of distance, problems such as difficult convergence of algorithm training, large fluctuations in control quantity, and large cumulative deviation at the middle and final shift points are solved. Compared with the traditional LQR algorithm, the reinforcement learning guidance algorithm has significantly improved guidance accuracy and deviation adaptability, and has good versatility, which can be applied to small-scale formation maintenance issues.

For Falcon 9 rocket launch missions in 2024 and before, a reuse indicator system has been initially established. Statistical analysis is conducted in the time dimension and status dimension, and the development rules of Falcon 9 rocket one-stage reuse technology are initially obtained. By the analysis of the rules, the development and evolution process of Falcon 9 rocket recovery and reuse technology is divided into three stages. Finally, a preliminary prediction is made on the development of China's reusable rockets.