For the flaged structure used in the fully friction stir welded tank bulkhead of the next-generation launch vehicle, strain measurements are conducted at typical locations during the flange assembly, welding, repair welding, and hydrostatic testing processes. Additionally, finite element analysis (FEA) is performed to simulate the internal pressure loading of the tank bulkhead. The test results reveal significant non-uniform stress distribution in the flange fillet area after welding, while full stirring repair welding has a relatively small influence on the final stress level of the flange. Under internal pressure loading, the flange exhibit uneven stress distribution, leading to localized yielding at certain points. The experimental results validate the accuracy of the finite element method, demonstrating its applicability for evaluating the effectiveness of subsequent structural optimizations.

To investigate the effects of grease degradation induced by long-term storage on the control characteristics of servo systems, the viscosity properties of the grease during storage are analyzed according to the results from the high-temperature accelerated storage test. Subsequently, the friction of the roller screw transmission is modeled to investigate the influence of lubrication degradation on the friction characteristics of servo system. Eventually, the friction models for various lubrication conditions are integrated into the servo system control simulation model to assess the impact of lubrication degradation on its performance characteristics. The obtained result is that the viscosity properties do not exhibit a clear correlation with the accelerated storage time. Selecting the degradation grease with high viscosity as the research subject, analysis indicates that the lubrication causes the increase of friction torques, the attenuation in amplitude and phase hysteresis in mid-high frequency range in servo system control characteristics. Besides, the attenuation and hysteresis aggravate as the load increases.

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.

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.

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.

Selective laser melting (SLM) technology is a key technology for parts manufacturing in the aerospace field. With integrating the overall structural optimization design and SLM technology, the overall lightweight manufacturing of complex components can be achieved. In view of the high-performance manufacturing requirements of parts in the aerospace field, the progress in the manufacturing of complex integral components and lightweight structures in the aerospace field by SLM technology in recent years is introduced, and the future development direction is pointed out.

In response to the problems of large deformation, multi-contacts, and time-varying folding stiffness during the deployment of flexible folding spacecraft, research has been conducted on the dynamic modeling methods of the deployment process of large-flexibility folding structures. Based on the folding method of such large-flexibility structures, a typical folding model is simplified and extracted, and a three-dimensional finite-segment discrete model suitable for the deployment of large-flexibility folding structures is established using the finite segment method. Utilizing vector mechanics, a mechanical model of the connecting forces between adjacent units is derived from the Newton-Euler equations, and the stiffness matrix of the connection forces is provided. Nonlinear equivalent contact spring damping and a continuous friction coefficient Coulomb friction force model are introduced to simulate the contact and friction states between units, ensuring the stability and efficiency of the solution. A time-varying nonlinear elastic connection model at the crease is proposed, along with a parameter identification method for bending stiffness. Using ADAMS software, dynamic simulations of deployment are conducted for typical folding models under four working conditions, and corresponding deployment experiments are designed. The comparison between the two results shows that the change in tensile force during the deployment process of typical folding models matches well, validating the feasibility and accuracy of dynamic modeling for such structures, and laying the foundation for subsequent simulations of the overall structure's unfolding.

As a critical component of the space transportation system, solid launch vehicle has advantages such as full-vehicle storage, versatility for sea-based and land-based launch, rapid response, and low requirements for launch support. The development process and overall technical scheme of Smart Dragon-3 solid rocket are introduced. In addition, the practical experience in the development of solid launch vehicles is drawn as a brief summery. Furthermore, the series development of solid launch vehicles is claimed, based on the analysis of the future positioning of solid rocket development. The carrying capacity of medium-sized solid launch vehicle needs to be improved, through research innovation, scale development and optimization of comprehensive cost. In this case, the demands of various launch orbits can be satisfied by the style of offhand sea launch.

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