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.

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 order to solve the problem of vulnerability of the missile-loaded motor shaft and bearing in the high overload environment of 23 000g guided artillery projectile, the anti-high overload brushless DC motor using a combination of disc spring and special steel ball for buffering and vibration damping is designed. Firstly, the acceleration load curve of the missile-borne motor is obtained by calculation. The bearing and shaft of the brushless DC motor are analyzed to be the failure prone parts. Secondly, according to the energy absorption characteristics of dish spring and steel ball, a composite damping structure of brushless DC motor combining dish spring and special steel ball is designed in the case of limited structural space. And based on this structure, a high speed and fast response anti-high overload motor is designed. Finally, the simulation and experimental analysis of the designed motor show that the design of the composite buffer structure can effectively reduce the stress and deformation of the motor shafting parts under the high overload environment. The structure of the anti-high overload motor has no obvious damage after the Marshall's drop hammer test, and the working performance meets the requirements of precision guidance control.

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

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.

The theoretical development of weapon equipment system of systems engineering is reviewed from three aspects of the formation process of combat System of Systems, such as mutual reference relationship and connotation, research status of main links, intelligence, toughness and emergence, and the theoretical development of weapon equipment System of Systems engineering under the guidance of system engineering theory is summarized and analyzed. In the space field, the System of Systems project is the main carrier to carry out application exploration in two aspects of technology and management, based on which the future development direction is prospected.

The engine nozzle is prone to work with a state of over-expansion in a high-pressure underwater environment, which will influence the jet flow field and thrust. Experiments of over-expansion supersonic underwater gas jets at different co-flow velocities are conducted using a circulating water tunnel, various forms of wake cavity and their corresponding thrust time-frequency characteristics are analyzed. It is shown that at low velocities, the over-expanded gas jet is difficult to form a cavity attached to the wake or a pulsating foam-type wake cavity. Under such flow conditions, the vehicle experiences pronounced thrust oscillations with a rich frequency spectrum (36 to ${743}\mathrm{\;{Hz}}$). As the Froude number at the co-flow velocity increases to ${Fr}= {8.57}$, the jet eventually forms an intact tail cavity, at which point the amplitude of the thrust oscillations decreases significantly and the mean thrust value increases significantly. The internal gas reflux phenomenon in the jet-induced tail cavity is also directly observed, and the observed reflux velocity at ${Fr}= {8.57}$ is about ${1.13}\mathrm{\;m}/\mathrm{s}$.

During the flight of aircraft, a coupling effect between the fluid aerodynamic forces and the structural elastomer will be formed, and this interaction may cause different degrees of damage to the divergence and jitter of the elastomer, resulting in safety risks. A numerical simulation method of fluid-structure coupling based on time-space conserved element solution and immersion boundary is proposed. The method of time-space conserved element solution is used to calculate the fluid domain, and the submerged body-fitted mesh boundary method is used to identify the fluid-structure coupling boundary surface. Taking NACA0018 as an example, the cloud image of wing outflow field pressure and velocity at different angles of attack is obtained through simulation data. At the same time, the buffeting amplitude of the wing under different inlet velocity and its rule are studied. The research shows that the fluid-structure coupling method has high accuracy and stability in solving high-speed compressible flows with complex flow patterns, including shock wave or detonation and large deformation problems, providing a reference research method for related research.

To achieve attitude stability and depth control of a underwater vehicle, the dynamic characteristics and the influence of the tail rudders and sliding force on its dynamic characteristics are analyzed. The system is divided into three loops, and the controllers are designed for them. According to the damping characteristics of the system, pole placement is performed on the diagonal rate loop, followed by hysteresis correction on the overload loop based on the frequency domain characteristics of the system. Finally, the time domain characteristics of the depth loop are improved by adjusting the gain. Through simulation experiments, it has been verified that the control law designed can achieve attitude stability and depth control of a underwater vehicle, and has certain anti-interference ability. The linear control methods used in the article are common in engineering practice, and the calculation of controller parameters is based on the system's time-domain and frequency-domain performance indicators. The physical meaning is clear, and it has certain reference significance for engineering practice related to underwater vehicle attitude control.