Launch Technology Research Articles

EXPRESS: Timing Legitimacy: Identifying the Optimal Moment to Launch Technology in the Market

EXPRESS: Timing Legitimacy: Identifying the Optimal Moment to Launch Technology in the Market

Effects of cross flow on the launching process of submarine-launched vehicle considering the 6-DOF motion at barrel-exit stage

Submarine-launched vehicle (SLV) is a research hotspot due to its strong strike capability, among which underwater launching technology is a key issue hindering its development. In this paper, a numerical model is proposed to simulate the launching problem of SLV. The high nonlinearity induced by the coupling of multi-degree-of-freedom motions and the interaction between fluid and structure is solved. Specifically, the 6-DOF motion model of structure considering its strong added-mass effect, cavitation model and collision model are adopted. This numerical model is firstly validated by simulating the launching of SLV in still water. And then, the applicability of this model is discussed, as well as the effect of cross flow and initial launching velocity on the launching process. The results indicate that proposed numerical model could be used under both low-speed and high-speed cross flow situations. Cross flow changes the attitude and locomotion state of SLV. When flow velocity exceeds 1.25 m/s, the collision occurs between SLV (with the initial launching velocity of 40 m/s) and its barrel. This obtained locomotion of SLV after leaving its barrel causes the launching failure. Besides, a method of increasing launching velocity is introduced to promote the success rate of launching in high-speed cross flow situation.

Small Solid-Model Rocket Design and Soft Landing Trajectory Planning

A recoverable rocket is one of the keys to reusable launch technology. Currently, most recoverable rockets are powered by liquid engines, which are costly and complex compared to solid engines. In this paper, we perform soft landing trajectory planning for the designed solid rocket. First, a small model rocket equipped with a landing engine is innovatively designed. Second, a six-degree-of-freedom motion model of the rocket is established, and a minimum-landing-error problem is formed based on the landing engine. Third, successive convexification algorithm is applied to solve it. In the algorithm, a method of quaternion constraint correction is proposed to avoid the infeasibility of the problem. Lastly, the correctness and robustness of the algorithm are verified via three simulations. The possibility of rapid trajectory generation is verified by code optimization on a high-performance digital signal processor.

Research on the Characteristics of Shale Three-axis Compression Sound Emission Features

In the shale gas development, the lack of stability caused by the transformation of the reserve layer is an important engineering problem to be solved. This article is based on the compression test and sound launch technology. The impact of rock destruction, crack type, and the process of sound launch features during compression. The results show that: The bell counting count of sound transmission is volatile and there is a gap. On the eve of the stress peak, the bell counting count rapidly increased to the maximum value; the energy is small in most of the time, the energy increases when the crack expansion, and the broken damage occurs in the rock -sample. At the same time, the energy released is the most.

Research Progress on Surface Damage and Protection Strategies of Armature-Rail Friction Pair Materials for Electromagnetic Rail Launch.

Electromagnetic rail launch technology has attracted increasing attention owing to its advantages in terms of range, firepower, and speed. However, due to electricity-magnetism-heat-force coupling, the surface of the armature-rail friction pair becomes severely damaged, which restricts the development of this technology. A series of studies have been conducted to reduce the damage of the armature-rail friction pair, including an analysis of the damage mechanism and protection strategies. In this study, various types of surface damage were classified into mechanical, electrical, and coupling damages according to their causes. This damage is caused by factors such as mechanical friction, mechanical impact, and electric erosion, either individually or in combination. Then, a detailed investigation of protection strategies for reducing damage is introduced, including material improvement through the use of novel combined deformation and heat treatment processes to achieve high strength and high conductivity, as well as surface treatment technologies such as structural coatings for wear resistance and functional coatings for ablation and melting resistance. Finally, future development prospects of armature-rail friction pair materials are discussed. This study provides a theoretical basis and directions for the development of high-performance materials for the armature-rail friction pair.

Optimum Design of a Reusable Spacecraft Launch System Using Electromagnetic Energy: An Artificial Intelligence GSO Algorithm

Due to its advantages of high acceleration, reusability, environmental protection, safety, energy conservation, and efficiency, electromagnetic energy has been considered as an inevitable choicefor future space launch technology. This paper proposes a novel three-level orbital launch approach based on a combination of a traditional two-level orbital launch method and an electromagnetic boost (EMB), in whichthe traditional two-level orbital launch consists of a turbine-basedcombined cycle (TBCC) and a reusable rocket (RR). Firstly, a mathematical model of a multi-stage coil electromagnetic boost system is established to develop the proposed three-level EMB-TBCC-RR orbital launch approach, achieving a horizontal take-off–horizontal landing (HTHL) reusable launch. In order to optimize the fuel quality of the energy system, an artificial intelligence algorithmparameters-sensitivity-basedadaptive quantum-inspiredglowworm swarm optimization (AQGSO)is proposed to improve the performance of the electromagnetic boosting system. Simulation results show that the proposed AQGSO improves the global optimization precision and convergence speed. By using the proposed EMB-TBCC-RR orbital launch system and the optimization approach, the required fuel weight was reduced by about 13 tons for the same launch mission, and the energy efficiency and reusability of the spacecraft was greatly improved. The spacecraft can be launched with more cargo capacity and increased payload. The proposed novel three-level orbital launch approach can help engineers to design and optimize the orbital launch system in the field of electromagnetic energy conversion and management.

Launch Dynamic Simulation of a Compressed-Air Launcher for Fire Suppression

This paper focuses on improving fire suppression performance through the use of compressed-air launching technology. A launch dynamics calculation model of a compressed-air launcher is presented, developed using VC++ programming, to simulate the acceleration process of a fire-extinguishing bomb in a barrel. By analyzing the influences of various structural and initial parameters on interior ballistics variations, the effectiveness of the calculation model and program in accurately simulating the launching process is demonstrated. The calculation results indicate that the bore pressure follows a similar trend to that of traditional gunpowder launching. Additionally, it is found that specific structural parameters, such as nozzle diameter and gas cylinder volume, have a direct impact on interior ballistics variations. Notably, the nozzle diameter positively affects the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency. To ensure an optimal launch effect and efficiency, the nozzle diameter should be selected to be more than half of the launcher caliber. Similarly, the gas cylinder volume positively influences the peak pressure and muzzle velocity while negatively affecting the gas transfer efficiency and launch efficiency. Furthermore, the initial pressure in the gas cylinder exhibits a positive linear relationship with both the peak pressure and muzzle velocity but a negative linear relationship with the gas transfer efficiency and launch efficiency. The loading position minimally impacts the peak pressure and muzzle velocity but slightly enhances the gas transfer efficiency and launch efficiency. Finally, it is observed that launch angles do not affect the interior ballistic process. The research findings provide valuable theoretical guidance for determining the working parameters of compressed-air accelerated fire-extinguishing bombs.

Research on the Control Method of Micro-gas Turbine Power Supply Modulation System for Primary Energy in Electromagnetic Launch Technology

Combining the advantages of micro-gas turbine generation system (MTGS) and power converters, moreover, comparing the various design ideas for the primary energy of electromagnetic launch technology, we design a primary energy to meet the reliability, stability, safety and portable of electromagnetic launch technology. We discuss the control ideas and methods to be adopted in this system, the first step is to output a stable DC bus voltage through rectification, and then to step up the voltage through a series resonant converter to achieve the desired output voltage. Through theoretical analysis and simulation, it reveals the effect of this load on the performance of MTGS, and the parameter optimization design is combined with the voltage outer loop control strategy to achieve the purpose of outputting stable voltage. We used a ARM controller to implement the control of this system to measure the response curve of the system under different input commands. According to the theoretical analysis, numerical simulation and experimental results, the control strategy designed in this paper can better meet the performance index requirements of micro-gas turbine engine (MTE) and power converter as well as the control method is simple and easy to implement in engineering. The results of this paper confirm the feasibility of this primary energy application for electromagnetic launch technology.

2022 International Conference on Defence Technology, Changsha, China

I am hugely delighted and excited to be writing this preface to the Proceedings of the 2022 International Conference on Defence Technology (ICDT). This is the third ICDT, following on from the very successful ICDTs held in 2018 and 2020. The ICDTs are intended to take place at intervals of approximately 18 months. The 2022 ICDT is co-chaired by Professor Changgen Feng and myself and supported by the Editorial Office of Defence Technology.The ICDT provides an opportunity for scientists, engineers, and others to report, share and discuss current research and advances in defence technology and their visions for the future. The symposium allows exposure to the most current state-of-the-art technology in defence science, provides opportunities for interactions with some of the world’s leading experts in the field of defence science, and offers the chance to present, exhibit, and share scientific research and development with an international group of professionals.A wide range of papers is encouraged at the ICDT, from work in progress through to high quality scientific papers. These 535 papers comprise an extensive range of defence science and technology areas covered by the symposium: Advanced Simulation, Energetic Materials, Advanced Materials, Advanced Manufacturing Technology, Photoelectric Information Technology, Impact Dynamics (Explosion, Impact & Protection), Directed Energy & Hypersonic Technology, Advanced Launch Technology, Autonomous Control Technology, Ballistics & Applications.This is the third ICDT Proceedings to be published by IOP Publishing Ltd as an open access volume of the Journal of Physics: Conference Series (the 2020 ICDT Proceedings were published in 2 parts). The Proceedings were enabled by the good cooperation between the ICDT and Defence Technology journal, which is published by KeAi Publishing Communications Ltd. I would like to thank the Editors and the Editorial Office for their dedicated, hard and expeditious work in producing this issue. I also thank the technical reviewers of the papers contained in these Proceedings and the sponsors of the ICDT who have helped to make the ICDT possible.I hope you will find these Proceedings stimulating and very interesting. ICDT provides an opportunity to develop an understanding of the entire realm of defence science and technology outside of the reader’s specialist area. I therefore highly commend these Proceedings to you.Clive Woodley, 2022 ICDT co-chair.London, UK.List of committees are available in this Pdf.

Investigation of the Free-Fall Dynamic Behavior of a Rectangular Wing with Variable Center of Mass Location and Variable Moment of Inertia

In recent years, the air-drop launch technology of near-space UAVs has attracted much attention. Between downfall from the carrier and the flight control system’s initiation, the UAV presents free-fall movement. This free-fall process is very important for the control effect of the flight control system and is also crucial for the safety of the UAV and the carrier. Focus is required on two important dynamic parameters of the UAV: the moment of inertia and the center of mass position. In this paper, we used a quasi-steady model proposed by predecessors to address the flat-plate falling problem with modifications to describe the freely falling motion of the wing. Computational fluid dynamics (CFD) were used to simulate the free-fall movement of the wing with various parameters, and the wing release behavior was analyzed to check the quasi-steady model. Research shows that the movement characteristics of the falling wing are mostly reflected in the longitudinal plane, and the developed quasi-steady analytical model can more accurately describe the dynamic behavior of free-fall to some extent. By using CFD methods, we further investigated the aerodynamic performance of the free-fall wing. The results show that the wing mainly presents tumbling and fluttering motion. Changing the moment of inertia around the tumbling axis changes the tumbling frequency and the time point as the wing enters tumbling. In contrast, changing the position of the center of mass significantly changes the form of falling and makes the free-fall motion more complex. Therefore, it is necessary to carefully configure the center of mass in the UAV design process.

Inductance Gradient in Electromagnetic Launcher Under Channel Cooling Condition

Avoiding the ablation on the rail surface and obtaining large enough electromagnetic thrust to push the armature forward to high speed are two core contents of the electromagnetic launch technology. Reducing the ablation on the rail surface as much as possible can effectively extend the service life of the electromagnetic launcher (EML). The greater the electromagnetic thrust, the greater the initial velocity of the armature launched by the EML. The ablation on the rail is closely related to the temperature of the rail surface, and the electromagnetic thrust is proportional to the inductance gradient in the rails. The water flowing through cooling channels in rails can take away most of the heat generated by megaampere current flowing through the rails and armature in a few milliseconds. In this way, serious ablation on the rail can be avoided. Although the cooling channels are very helpful to reduce the ablation on rails, if the location distribution of the cooling channels in rails is not appropriate, the inductance gradient in the rails will be affected. This will affect the electromagnetic thrust in the EML. Therefore, the expressions of the inductance gradient in the rails with or without cooling channels are deduced and verified by the FEA in this article. The influence of the position distribution of the cooling channel on the inductance gradient in rails is analyzed. The results show that, with the increase of frequency, the influence of cooling channels on the inductance gradient in the rails diminishes gradually; if the distance between the cooling channels and the surface of the rails is greater than a certain value, the inductance gradient is no longer influenced by the cooling channels. At last, the relationship among <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L} ^{\prime} $ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L} _{\mathbf {1}}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L} _{\mathbf {2}}$ </tex-math></inline-formula> are fit in this article. It can be used to find the rail parameters that meet both thermal management and electromagnetic driving force requirements.

A Control Method of Projectile Spinning Speed Based on Magnetic Field Vector Transformation in a Railgun

This article studies the spinning speed control method of projectile in a railgun. The core idea is to adjust the current in extra rails to produce a controllable magnetic field and rotational torque. Then, the spinning speed and direction can be accurately controlled. Based on the Biot–Savart law, a model is established to analyze the rotating characteristics affected by the current waveform in the extra rails. Results show that this method is feasible since the spinning speed is linear and controllable. It can achieve a high speed to meet the fly spinning stability. It is also found that the increase of spinning speed is at the expense of muzzle velocity, and the launching system cannot achieve the maximum spinning speed and maximum muzzle velocity at the same time. The greater the energy given to the inner rails, the higher the muzzle velocity, and the faster the spinning speed. Without a large muzzle velocity, it may not achieve a high spinning speed. Finally, the influence of different parameters on the consistency of spinning speed is analyzed. The method proposed in this article can control the spinning speed accurately, which is of reference significance for the development of electromagnetic launch technology.

AI 공격용 드론 개발 방향 및 시사점

The role of attack drones in the ongoing war between Ukraine and Russia is drawing worldwide attention. In order to prepare for changes in the defense security environment and rapid decline in military resources, the Ministry of National Defense announced the National Defense Innovation 4.0 Basic Plan in March 2023, and established the concept of joint operation by reflecting the operation of AI-based manned and unmanned complex systems and new concept weapon systems. did Drones are the most important force in building manned and unmanned complex systems, and the dronebot combat system will be the basis for promoting Defense Innovation 4.0. Drones are a system that can be operated for multiple purposes that change their use according to mission equipment, and it is key to have advanced technology that is suitable for the future battlefield environment and efficient. If the existing attack drone is an operating system in which combatants remotely control the ground control device while watching the ground control device, the future direction of the development of attack drones for the Korean military to apply to dronebots is an AI attack drone in which the drone detects the target by itself and directly strikes and self-destructs. will develop into In order to develop AI attack drones, not only the performance of the drone system, but also AI-based cutting-edge technology for object tracking technology, object identification technology and shape recognition technology of reconnaissance equipment (EO/IR), which is mission equipment, as well as attack ammunition or Small, high-performance warhead design technology, ultra-small fuze design technology, shock absorption and launch control device technology, etc. must be developed to mount the projectile. In addition, as the amount of image information acquired through mission equipment increases, high-speed data transmission technology development to improve the transmission rate between the aircraft and the ground control equipment in real time must be simultaneously developed. It is necessary to quickly overcome drone and AI technologies, which are currently very poor compared to advanced countries, and take the lead in developing intelligent AI attack drones with excellent autonomy based on Korea's excellent ICT technology. Therefore, this study aims to find out the technological trends of domestic and foreign attack drones and to consider the development plans and tasks of AI attack drones.

Research on the sealed launching technology of underwater gun

With the progress of military technology, the underwater combat capability of the world’s major naval powers has developed rapidly. In order to effectively deal with the underwater threat, the related technology research of underwater gun is carried out based on supercavitation technology. Due to the particularity of underwater launch environment, the research of underwater gun launch technology still faces many problems. In this paper, the sealed launching technology of underwater gun is taken as the research object. By comparing with submerged launching and air curtain launching, the advantages of sealed launching technology of underwater gun are analyzed, and the muzzle sealing technology, sealed launching interior ballistic technology and continuous stable water entry technology of underwater gun are preliminarily studied. Opinions and suggestions are put forward for related technologies, which can provide reference for underwater gun launch technology research and engineering practice in the future.

Hydrodynamic Characteristics of Three-Bucket Jacket Foundation for Offshore Wind Turbines During the Lowering Process

The three-bucket jacket foundation is a new type of foundation for offshore wind turbine that has the advantages of fast construction speed and suitability for deep water. The study of the hoisting and launching process is of great significance to ensure construction safety in actual projects. In this paper, a new launching technology is proposed that is based on the foundation of the three-bucket jacket for offshore wind turbine. A complete time domain simulation of the launching process of three-bucket jacket foundation is carried out by a theoretical analysis combined with hydrodynamic software Moses. At the same time, the effects of different initial air storage and sea conditions on the motion response of the structure and the hoisting cable tension are studied. The results show that the motion response of the structure is the highest when it is lowered to 1.5 times the bucket height. The natural period of each degree of freedom of the structure increases with the increase of the lowering depth. The structural motion response and the hoisting cable tension vary greatly in the early phases of Stages I and III, smaller in Stage II, and gradually stabilize in the middle and late phases of Stage III.

Research on Pulse Power Wireless Communication Network Based on LoRa Technology

In this paper, the engineering of pulse power supply in electromagnetic launch technology is studied in depth, the advantages and disadvantages of optical fiber communication transmission currently used are analyzed, and then the requirements for data transmission of pulse power supply system are summarized, and several commonly used wireless communication technologies are analyzed and compared, such as ZigBee, LoRa, SigFox, NB IoT, 5G, etc. According to the comprehensive comparison of these technologies in transmission distance, rate, bandwidth, security, time delay, self built network and other aspects, the scheme of using LoRa wireless communication technology to replace optical fiber transmission is finally determined, and the LoRa wireless communication network construction, controller hardware circuit design, module software program, data transmission communication protocol, data encryption, data storage and other contents in the scheme are further designed in detail, It also predicts the further research and development of LoRa wireless communication technology in pulse power supply.

A simulation method for the electromagnetic railgun based on equivalent circuit

As a typical electromagnetic launcher, electromagnetic railguns have attracted widespread attention for their broad military application prospects. It is known that skin effects occur during electromagnetic railgun launch. How to quickly and accurately simulate these skin effects is of importance for the application of electromagnetic launch technology. This paper proposes a static two-dimensional finite element model in series with one variable equivalent inductance and three resistances for simulating the dynamic electromagnetic railgun launch. Two skin effects are presented by changing equivalent inductance and resistances. For an electromagnetic railgun including two rails of length of 2 m and width of 0.3 m and square armature of 0.3 m long, after 4.23 ms under a pulse current of a peak of 1 MA, the simulation results based on this proposed static 2D model show that the armature can leave the rails with a velocity and acceleration increasing to 1,464 m/s and 614,876 m/s2, respectively. For an equivalent circuit connected in series, the equivalent inductance, AC resistance, velocity skin effect resistance, and back EMF resistance are 0.49 μH, 2.5 mΩ, 7.1 mΩ, and 4.44 mΩ, respectively, whereas the breech voltage can increase to 1.36 kV. The proposed method simplifies the meshing in the finite element model, saves computational cost, and is conducive to study electromagnetic railgun design and projectile magnetic field shielding. Key words: Electromagnetic railgun, equivalent inductance, equivalent resistance. Tables 1, Figs 7, Refs 10.

Design and Analysis of Hybrid Armature for Electromagnetic Launch Technology

Velocity skin effect (VSE) and subsequent current melt wave (CMW) is one of the most prominent causes of transition in an electromagnetic launch (EML) technology. Extensive research on the phenomenon led to the development of a monolithic C armature design that provides optimum contact pressure and a contact region at the armature–rail (A/R) interface. However, in the working velocity regime of an EML, frictional heating at the contact interface dominates wear, heat generation, and contact transition. Because of a long current path, the C armature generates contact forces of the same magnitude as the thrust force. A hybrid armature design is proposed based on previous recommendations that provide mechanical load carrying capacity, compliance, and a monolithic design akin to a C armature while providing a short current path to reduce frictional loss. The resulting hybrid armature has 33% less parasitic mass that delivers 22% higher kinetic energy to the payload.

An explosively driven launcher capable of $$10\,\mathrm{km\,s}^{-1}$$ projectile velocities

Launching large (> 1 g) well-characterized projectiles to velocities beyond 10 km/s is of interest for a number of scientific fields but is beyond the reach of current hypervelocity launcher technology. This paper reports the development of an explosively driven light-gas gun that has demonstrated the ability to launch 8 mm diameter, 0.36 g magnesium projectiles to 10.4 km/s. The implosion-driven launcher (IDL) uses the linear implosion of a pressurized tube to shock-compress helium gas to a pressure of \SI{5}{\giga\pascal}, which then expands to propel a projectile to hypervelocity. The launch cycle of the IDL is explored with the use of down-bore velocimetry experiments and a quasi-one-dimensional internal ballistics solver. A detailed overview of the design of the 8 mm launcher is presented, with an emphasis on the unique considerations which arise from the explosively driven propellant compression and the resulting extreme pressures and temperatures. The high average driving pressure results in a launcher that is compact, with a total length typically less than a meter. The possibility to scale the design to larger projectile sizes (25 mm diameter) is demonstrated. Finally, concepts for a modified launch cycle which may allow the IDL to reach significantly greater projectile velocities are explored conceptually and with preliminary experiments.

Method of Calculating Inductance Gradient for Complex Electromagnetic Rail Launcher

Electromagnetic rail launch technology has made impressive progress; however, the analytical method of calculating the inductance gradient for a complex electromagnetic launcher is still insufficient. By fully considering the characteristics of electromagnetics and current distribution in a device, this paper describes a model of the current skin effect by simplifying the line current distribution in the device. Based on Biot–Savart Law, an analytical method of calculating inductance gradient for an electromagnetic rail launcher with complex structure is proposed. This method has the advantages of fast calculation speed and accurate calculation results. Because of error analysis, the calculated value relatively corresponds to the simulation result of the eddy current field. To reflect the transient electromagnetic emission process, the effects of different configurations, current frequency, and armature position on the inductance gradient are further summarized. The results show that the error rate of this method in calculating the inductance gradient is about 4%, which meets the requirement for calculation accuracy. The inductance gradient of the enhanced four-rail electromagnetic launcher is about 2.22 times that of the nonenhanced one due to the equal conditions; the inductance gradient decreases with the increase in current frequency and decreases as the armature approaches the muzzle.