Experimental research on the launching system of auxiliary charge with filter cartridge structure

A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.

Research on the Reliability Centered Maintenance Plan of a Launching System

Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.

Study on the coupling calculation method for the launch dynamics of a self-propelled artillery multibody system considering engraving process

The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.

A new method for evaluating the firing precision of multiple launch rocket system based on Bayesian theory

How to effectively evaluate the firing precision of weapon equipment at low cost is one of the core contents of improving the test level of weapon system.A new method to evaluate the firing precision of the MLRS considering the credibility of simulation system based on Bayesian theory is proposed in this paper.First of all,a comprehensive index system for the credibility of the simulation system of the firing precision of the MLRS is constructed combined with the group analytic hierarchy process.A modified method for determining the comprehensive weight of the index is established to improve the rationality of the index weight coefficients.The Bayesian posterior estimation formula of firing precision considering prior information is derived in the form of mixed prior distribution,and the rationality of prior information used in estimation model is discussed quantitatively.With the simulation tests,the different evaluation methods are compared to validate the effectiveness of the proposed method.Finally,the experimental results show that the effectiveness of estimation method for firing precision is improved by more than 25%.

Analysis of the Gravity-1 Sea Launch System and Technical Features

Sea launch has the characteristics of flexible launching points, high landing area safety, and good economy. In recent years, it has become one of the important launch methods. Since 2019, China has carried out a total of 11 successful sea launches. The Gravity-1(YL-1) sea launch system consists of a launch vehicle system and a sea launch platform. The sea launch program includes roll on/roll off boarding, sea mooring, sea maneuvering, anchoring and positioning, system testing, and formal launch. Through the maiden flight of YL-1, the design and manufacturing technology of large tonnage dedicated launch ship, launch vehicle vertical transfer and roll on/roll off boarding technology, anti-shake technology for sea launch, simple inflatable flexible insulation protective cover technology, and remote wireless measurement and control technology have been fully verified.

Research on agile space emergency launching mission planning simulation and verification method

Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.

Configuration Synthesis and Grasping Performance Analysis of Multi-Loop Coupling Capture Mechanism for Launch and Recovery of Torpedo-Shaped Autonomous Underwater Vehicle

Research of capture mechanisms with strong capture adaptability and stable grasp is important to solve the problem of launch and recovery of torpedo-shaped autonomous underwater vehicles(AUVs).A multi-loop coupling capture mechanism with strong adaptability and high retraction rate has been proposed for the launch and recovery of torpedo-shaped AUVs with different morphological features.Firstly,the principle of capturing motion retraction is described based on the appearance characteristics of torpedo-shaped AUVs,and the configuration synthesis of the capture mechanism is carried out using the method of constrained chain synthesis.Secondly,the screw theory is employed to analyze the degree of freedom(DoF)of the capture mechanism.Then,the 3D model of the capture mechanism is established,and the kinematics and dynamics simulations are carried out.Combined with the capture orientation requirements of the capture mechanism,the statics and vibration characteristics analyses are carried out.Furthermore,considering the capture process and the underwater working environment,the motion characteristics and hydraulics characteristics of the capture mechanism are analyzed.Finally,a principle prototype is developed and the torpedo-shaped AUVs capture experiment is completed.The work provides technical reserves for the research and development of AUV capture special equipment.

A CombustionModel for Explosive Charge Affected by a Bottom Gap in the Launch Environment

Launch safety of explosive charges has become an urgent problem to be solved by all countries in the world aslaunch situation of ammunition becomes consistentlyworse.However, the existing numericalmodels have differentdefects. This paper formulates an efficient computational model of the combustion of an explosive charge affectedby a bottom gap in the launch environment in the context of the material point method. The current temperatureis computed accurately from the heat balance equation, and different physical states of the explosive charges areconsidered through various equations of state. Microcracks in the explosive charges are described with respectto the viscoelastic statistical crackmechanics (Visco–SCRAM) model. Themethod for calculating the temperatureat the bottomof the explosive charge with respect to the bottomgap is described. Based on this combustionmodel,the temperature history of a Composition B (COMB) explosive charge in the presence of a bottom gap is obtainedduring the launch process of a 155-mm artillery. The simulation results show that the bottom gap thickness shouldbe no greater than 0.039 cm to ensure the safety of the COM B explosive charge in the launch environment. Thisconclusion is consistent with previous results and verifies the correctness of the proposed model. Ultimately, thispaper derives amathematical expression for themaximumtemperature of the COMB explosive chargewith respectto the bottomgap thickness (over the range of 0.00–0.039 cm), and establishes a quantitative evaluationmethod forthe launch safety of explosive charges.The research results provide some guidance for the assessment and detectionof explosive charge safety in complex launch environments.

The Launch of IEA Report World Energy Investment 2024 Successfully Held

On July 18,2024,the Launch of IEA Report World Energy Investment Report 2024 was released at Peking University.This conference was co-hosted by the International Energy Agency(IEA)and the Institute of Energy,Peking University.

NWES in brief

China’s reusable carrier rocket completes first 10-km VTOL test China’s reusable carrier rocket successfully completed a 10-km vertical take-off and landing(VTOL)flight test at the Jiuquan Satellite Launch Center in northwest China on June 23.

SCIENCE AND TECHNOLOGY

Xichang Space Launch Site Reaches 200th Mission,China's Xichang space launch site,the inland launch site of the Xichang Satellite Launch Center,located in the southwestern province Sichuan,on February 3 achieved a milestone by completing its 200th launch mission.Carried by a Long March-2C carrier rocket,the 11 Geely-02 constellation satellites took off at 7:37 a.m.(Beijing Time)from the launch site,and entered the preset orbit.

Commercial Aerospace: The Next Launchpad For the Chinese Economy

On December 29,2023,the first launch service tower was completed at the Hainan International Commercial Aerospace Launch Center,marking a key step forward in building the launch capacity of China’s first commercial aerospace launch site.On December 10,a Hyperbola-2 methane-liquid oxygen reusable verification rocket was launched successfully,marking the first recovery of reusable carrier rockets in China.

Trajectory Design and Flight Result of Gravity-1 Launch Vehicle

Gravity-1(YL-1) launch vehicle completed its maiden flight from the Yellow Sea near Haiyang City, Shandong Province, on January 11, 2024, this mission successfully launched three Yunyao satellites into their 500 km orbit. The YL-1 has a performance of 4.2 tons for 500 km sun-synchronous orbit and 6.5 tons for low Earth orbit. The success of YL-1 has further enriched China's launch vehicle spectrum, and will facilitate the launch of medium and large satellites and satellite constellations. In this paper, the flight ballistic solution of YL-1 is introduced. The flight trajectory consists of seven flight segments. The trajectory design comprehensively considered the characteristics and safety requirements of the vehicle to achieve effective utilization of the performance. Through comparative analysis of the flight trajectory and the predicted trajectory, the result confirmed that the flight trajectory was consistent with the design results, the design methodology was correct, and the flight test met the expected requirements. Subsequently, the vehicle will be employed for commercial application launch services.

Technical Characteristics and Innovations of the Gravity-1 Launch Vehicle

On January 11, 2024, the Gravity-1 launch vehicle successfully carried out its maiden flight from a mobile sea platform off the coast of Haiyang in Shandong Province, sending three meteorological satellites, Yunyao-1 satellite No. 18-20, into an orbit about 500 km above the ground. The successful debut flight of Gravity-1 broke many records such as the world's largest solid launch vehicle, the first sea-launched strap-on launch vehicle in the world, with the maximum carrying capacity of current commercial launch vehicle in China. This flight marked a big step in the field of China's commercial space launch application. A new breakthrough has been made, which is of great significance for further expanding China's diversified and large-scale launch capabilities of medium and low orbit satellites, expanding the spectrum of China's launch vehicle types, and promoting the development of space science.

Application of Modelica Based Multi- Domain Modeling and Simulation for Gravity-1

In the R&D phase of Gravity-1(YL-1), a multi-domain modeling and simulation technology based on Modelica language was introduced, which was a recent attempt in the practice of modeling and simulation method for launch vehicles in China. It realizes a complex coupling model within a unified model for different domains, so that technologists can work on one model. It ensured the success of YL-1 first launch mission, supports rapid iteration, full validation, and tight design collaboration.

Introduction and Prospects of Gravity-1 Launch Vehicle’s Sea-Based Three Verticals Testing and Launch Mode

Gravity-1 was the world's first carrier rocket to adopt the sea-based “three vertical” testing launch mode. This article introduces the overall layout of the launch site and the workflow of rocket testing and launch for its maiden flight mission. The process of vertical assembly, vertical testing, vertical transportation, and sea-based hot launches are explained. Additionally, it provides an outlook on the improved “three vertical” testing and launch mode for future missions, such as land-based launches, rapid launches, and remote sea launches.

An Analysis on the Motion Characteristics of Fuel and Shell in Launching

The relative characteristics of motion of the fuel and shell upon launching is analyzed. By means of mechanical analysis and calculation, it is proposed that relative motion exists not only in the ranges between the fuel and shell of the warhead, but also in the fuel in different positions. The result of study indicates that the position of the fuel in the warhead has a marked influence on the relative motion, while the frictional coefficient between the fuel and shell has less influence upon it.

Analysis and discussion on launching mechanism and tactical electromagnetic railgun technology

This paper begins with a discussion on the significance of multi-physical fields in the research of railgun launching mechanism, followed by an introduction of research work about dynamic measurements and numerical simulations. The application of some measurement methods including the atomic emission spectrum, fiber-optic strain, optical level, pulsed X-ray, and high-speed video in observing the launching process was introduced. The models about the electromechanical dynamic processes and multi-physical fields in a railgun were developed. The mechanisms of the grooving, arc transition, and gouging were analyzed. These work provided a deeper understanding of launching mechanism of electromagnetic railgun. Some issues about the tactical railgun, such as the fiber composite overwrapped barrel, recoil,loading modes and eddy current loss were also discussed. Taking a medium-caliber launcher as an example, the basic process of design and analysis was introduced.

Calculation of wave and current loads on launching offshore jacket

It’s very complicated to calculate and analyze the wave and current loads on naval architectures since the sea condition is uncertain and complicated and the determinants vary from different form types and dimensions. For calculating the wave and current loads on upright small-long-size pipe, the Morrison equation is practical and applied. Jacket platform is a kind of offshore space frame structure comprised of lots of poles that are circular cylinders with small diameter and in the oblique status relative to seabed. In this paper, based on Morrison equation, the specific method and procedure calculating the wave and current loads on launching jacket are given and applied on a typical launching jacket. The instance shows that the method and procedure are convenient and make the calculation and analysis in good agreement with actual launching.

NONLINEAR DYNAMIC SIMULATION OF AN AXIALLY SLIDE-SPIN ROCKET FLEXIBLE SYSTEM WITH CLEARANCE

A hybrid approach is presented to investigate the dynamic behavior of anaxially slide-spin flexible rocket with nonlinear clearance. The equations of motion of the flexiblerocket are derived based upon Euler-Bernoulli beam theory and Hamilton principle and the finiteelement method. The characteristics of clearance between the spinning rocket and launcher areconsidered to be piecewise linear. Numerical solution is developed by direct integration method anddemonstrates the validity of the method. The coupled dynamic behavior of axial motion and transversevibrations of rocket are analyzed, and the influences of axially moving acceleration, spin speed,linking stiffness of elastic 'shoes', and the nonlinearity of clearance on the motion attitude ofrocket are studied.