Launch System Research Articles

Motion characteristics and T-foil based optimization of marine towed-cage in swell

Unmanned surface vehicles (USVs) are widely used in variety of ocean operations and are typically launched and recovered from a mother ship. However, their recovery can be challenging, especially when they encounter ocean swells. In this paper, the main research objective is to analyze the performance of a cage-type davit launch and recovery system, with a specific focus on the marine towed-cage used in this process. The study utilizes Computational Fluid Dynamics (CFD) to conduct a detailed analysis of the longitudinal motion characteristics of the marine towed-cage during towing conditions. It has been observed that while encountering ocean swell, the marine towed-cage, as a hollow-out surface towed vehicle, faces difficulties such as stern trimming, oscillations, and an unstable attitude. This instability is mainly attributed to an insufficient pitch restoring moment. In order to address these issues and to optimize the longitudinal motion of the marine towed-cage, the study proposes two aspects of optimization: geometric optimization and cable length selection. This involves designing a modified marine towed-cage equipped with a T-foil and using a constant and sufficiently long cable. Subsequent to implementation of the proposed optimization scheme, the modified marine towed-cage exhibits significant improvements such that high-frequency oscillations are reduced, large-amplitude trim by the bow is minimized, especially at high towing speeds, and the system becomes more adaptable to changes in towing speed. The research presented in this paper provides a better understanding of the seakeeping performance of the marine towed-cage under towing condition and contribute to the safer and more efficient recovery of USVs.

Low-Speed Space Launch System Computational Fluid Dynamics: A Comprehensive Overview

In this review paper, low-speed computational work from NASA Langley Research Center in support of the Space Launch System (SLS) is discussed. This information includes both historical and present efforts with the Kestrel computational fluid dynamics solver. The low-speed aerodynamics of SLS is highly complex, and the analysis of the unsteady flowfield requires significant computational efforts. The SLS mission profile varies from the vehicle static on the launch pad through high-speed ascent. This study focuses on the prelaunch as well as liftoff and transition portions of the flight both in proximity to the launch tower and in isolation. High-alpha conditions, as large as 90 deg, result in a flowfield dominated by massive, large-scale flow separation and asymmetric vortices. High-fidelity solutions require an unsteady computational formulation to accurately capture the aerodynamics of the vehicle. A detailed discussion of the computational approach is presented, followed by key efforts to support the program, both historic and present, including information that has been either published previously or that has never before been published external to NASA.

Ariane 6 – in-flight safety and space debris mitigation

Ariane 6 is the future large European Launcher launched from the Guiana Space Center (CSG). Besides, Ariane 6 launcher program corresponds to the first full application of the French Space Operations Act from the beginning of an European Launch System development.This paper summarizes how French Space Operations Act requirements have been finally implemented in the Ariane 6 Launcher System. It addresses hardware systems as well as software solutions, but also specific analysis performed to support compliance with the French Space Operations Act requirements. This paper identifies the definition and design of these different on-board systems contributing to flight safety and space debris mitigation along with their validation. Moreover it details the studies that have been performed to assess Ariane 6 compliance to the requirements of French Space Operations Act.This document addresses more specifically safety in flight beginning at lift-off and ending with launcher disposal after its main mission. Afterwards it covers also solutions implemented on Ariane 6 launcher and its mission definition in order to mitigate space debris generation.

A numerical simulation method for solving electromagnetic-mechanical coupling field

A new numerical simulation method based on the finite volume method has been proposed to address the challenges associated with the pseudo-oscillation phenomenon that occurs with an increased Péclet number, as well as determining an appropriate time step for electromagnetic-mechanical coupled physical field calculations. This method utilizes the concept of upwind from Computational Fluid Dynamics (CFD) to solve Maxwell's equations, a finite-volume method for discretizing the electromagnetic diffusion equations. Through computing typical electromagnetic field problems such as TEAM problem 9–1 and comparing the results to the literature, it has been confirmed that this method has sufficient computational accuracy to solve electromagnetic field numerical simulation problems containing moving conductors. Additionally, a three-dimensional simulation model of the electromagnetic coil gun has been established to verify the viability of the proposed method for solving magnetic field problems under the electromagnetic launch (EML) system. The study also examined the change in magnetic field strength and current density of the EML device during the launching process. The results lay the foundation for the technical application of this method.

Analysis of Suitability of Fixed-wing Aircraft for Launching Satellites into Low Earth Orbit

The use of near-Earth space for scientific and commercial purposes has skyrocketed in recent years. However, progress continues to be hampered by the cost and availability of vehicles relied upon for delivering payloads to the Earth’s orbit. The Riga Technical University (Latvia), with the assistance of the Technological University in Kielce (Poland), is developing a concept of a novel payload launch system. The implications of such a system for launching payloads into low Earth orbit (LEO) are presented in the article. The system, intended for launching small spacecraft, comprises the A319 MPA transport airplane used as a platform aircraft and a three-stage payload carrier, codenamed LatLaunch. The first and second stages of the three-stage launch vehicle are unmanned winged aircraft. The third stage is a classic rocket which, once dropped from the launch platform, takes the payload to a specific height, at a given rate of speed and at a predetermined trajectory angle. The article presents the results of a study focusing on designing this system.

Control Strategies of Thrust Ripple Suppression for Electromagnetic Microgravity Facility

This paper presents an innovative solution that is able to suppress the thrust ripple in a high-power asynchronous linear induction motor (LIM) used in a microgravity experiment facility electromagnetic launch (MEFEL) system. By addressing the crucial need for low levels of thrust ripple in MEFEL applications, we propose a dynamic model-based adaptive controller (MAC) and an enhanced quasi-proportional-resonant (PR) controller. The MAC is designed to compensate for the inherent impedance asymmetry of the linear motor. The PR controller minimizes thrust ripple by eliminating harmonics within the current loop. A comparative analysis indicates that both MAC and PR control are effective in reducing harmonics, suppressing the thrust ripple, and maintaining system stability. Computer simulations show a noteworthy 75% reduction in the thrust ripple and a decrease in the negative current. Partial tests on the MEFEL device validate the practical efficacy of the proposed control methods, emphasizing the method’s ability to enhance the quality of microgravity in real-world scenarios significantly.

The impact‐induced deformation characteristics of polycarbonate panels

AbstractIn this study, the investigation of damage caused by a spherical steel projectile on the polycarbonate (PC) panels has been undertaken both numerically and experimentally. The material properties are obtained from both static and dynamic tests. High‐velocity impact experiments are performed using a pressure‐based projectile launching system. The effect of panel curvatures and impact locations on the deformation are investigated experimentally. The impact locations are selected as both at the plate center and near the edge of the plate. A validation study is performed by analyzing the impact response of a PC plate as previously presented in the literature and subsequently comparing it with the results obtained. An analysis of the impact behavior of PC panels is carried out through numerical simulations using finite element program (LS‐DYNA). The effect of boundary conditions on the impact response is also investigated numerically. Plastic strains, von Mises stresses, dent depth, and energy absorption are obtained. It is indicated by the results that the deformation behavior of PC panels exhibits a strain rate dependence. Additionally, the deformation behavior is influenced by panel curvatures and boundary conditions, emphasizing the necessity to consider these factors in the design of structures, such as canopies made of PC panels.Highlights Provides a comprehensive understanding of polycarbonate behavior. Emphasizes the influence of impact locations and panel curvatures. Dent depth and stress rise with panel curvature, crucial for design considerations. Emphasizes the significance of strain rate and boundary condition in design.

Modeling and Optimization of Interior Ballistics within Pneumatic Underwater Launchers

A new area of underwater equipment research focus is the use of underwater unmanned vehicles (UUVs) with launch mechanisms to deploy lightweight and small-sized robots for functions including communication, exploration, and detection. The internal ballistic mathematical model of the underwater launch system for small robots is established in this paper. The internal ballistic parameters and the robot displacement and velocity change rule over time are obtained. The optimization calculation of the crucial parameters to be determined by the particle swarm algorithm is completed. Following optimization, the gas cylinder’s initial pressure is 2 MPa, its capacity is 30 L, its opening area is 9.683 × 10−5 m2, and its opening time is 0.02 s. A numerical simulation is performed for the small robot’s underwater launch process, based on the mathematical and physical model supplied by Fluent 2020 software. The results yield the robot’s motion law and the properties of the flow field during the launch process. The purpose of the underwater launcher experiment is to determine the robot’s motion characteristics. The accuracy of the theoretical model is confirmed by comparing and analyzing the numerical simulation results with the actual data.

Design and construction of the army unmanned aerial vehicle with a new generation launch system «RPSKD-2»

The scientific article presents the design and construction of a two-case army unmanned aerial vehicle with a launch system of a new generation «RPSKD-2», which can be used for combat purposes. The study lists the main design units of the launch system, army unmanned aerial vehicle and cases. The combat equipment of the RPSKD-2 UAV provides for suspended armed cases that will be attached to the lower part. When designing and constructing an army UAV, foreign and domestic experience in machine-building production in this field of knowledge was studied. When modeling the UAV, the Compass and Siemens NX software product was used. The following general scientific methods for studying research materials were used in the article: analysis, deduction and modeling. The purpose of the study is to develop a two-case UAV with a launch system. This article is the first part of the study, in a number of author's scientific articles. Further publications of the authors will be devoted to the UAV structural and functional control system, which includes: telemetry, gyroscopes, automatic control system, sensors, controllers, engine, etc.

Unique Carbon Fibers for High-Temperature Applications

Carbon-carbon composites have been used for many decades in applications, such as rocket nozzles, brakes, and thermal protection systems (TPS). The material consists of carbon fiber in a matrix of carbon/graphite. Carbon-carbon provides structural performance while withstanding extremely high temperatures. The material has a low coefficient of thermal expansion and performs well under thermal shock. Interest in carbon-carbon has grown recently with the focus on hypersonic weapon systems that undergo high thermal shock. The challenge with hypersonics is to develop a thermal protection systems that does not ablate or erode so the control surfaces of a hypersonic weapon remain intact to allow for manuevering of the weapon in flight. Most carbon-carbon composites produced to date do ablate at elevated temperatures and there continues to be many applications for this material. Rocket nozzles and throats are a primary example and with the increases in launches of rockets, ablative carbon-carbon will still be key component in launch systems.

Influence of embedded structure on two-phase reactive flow characteristics for a small combustion chamber with a moving boundary

In special launch scenarios such as armament and aerospace, the scale of the launch system is severely restricted, which causes unstable combustion of propellant. An embedded structure for the small propulsion system driven by solid propellant is proposed to overcome this problem. This study aims to demonstrate the two-phase flow behaviors and launch safety of the combustion chamber with an embedded structure. A two-dimensional two-phase flow model based on the modified two-fluid theory is developed to describe the detailed two-phase flow behaviors in the combustion chamber during launching. Different from most of the existing studies, the constitutive equations determined from actual physical conditions are used to close the system of continuity equations. The numerical results are compared with that of the experiment to verify the accuracy of the numerical model. On this basis, the launch performance of the embedded structure is investigated. The numerical results indicate that the embedded structure facilitates the ignition process and reduces the risk of excessive pressure, but decreases the muzzle velocity at the same time. In addition, the effect of design parameters on launch safety is further investigated. Design parameters directly affect the launch safety, and the selection of reasonable parameters is a useful method for enhancing the launch performance.

An overview of aeroacoustics-related analyses for the Artemis-I mission

To improve noise scaling laws for rockets and heated, supersonic jets, this paper discusses jet aeroacoustics-related scalings for the Space Launch System (SLS). Data from four measurement stations at the Artemis-I launch, located 1.4–1.8 km from the launchpad, are used in the analysis. First, SLS maximum overall sound pressure levels are compared against other rocket noise measurements at the same scaled distance using effective nozzle diameter. Second, Strouhal number frequency-scaling is used to compare the one-third-octave sound pressure and power level spectra with other jets and rockets. Third, the Oertel convective Mach number is used to interpret a maximum directivity angle of 60°–70°. Finally, SLS’s acoustic efficiency is evaluated relative to that of other rockets.

Experimental and numerical study on ventilated cavitation of high-speed projectile

In this study, ventilated cavitating flow characteristics around an axisymmetric projectile are investigated by combining experiments and numerical simulations. Experiments were carried out with a Split–Hopkinson pressure bar launch system and the pressure-equaling exhaust technology. Modular projectiles are designed to experimentally investigate the influence of head shape and ventilatory volume on flow characteristics. Large eddy simulation model is applied to obtain more flow field information. Compared with the conical head projectile, the hemispherical head projectile has a thinner attached cavity and more local detachment of the cavity. The statistical structure of the velocity and pressure fluctuations are analyzed by combining histograms and Q–Q diagrams. The results show that the pressure drag is dominant in the total drag and the periodic pulsation of the tail cavity and the stable vortex structure at the tail cause the variation of drag. The larger cavity volume changes the actual shape of the projectile, making the drag of the conical head projectile higher. The evolution characteristics of the cavitating flow field around the projectile with different ventilatory volumes are obtained, and the relationship between pressure fluctuation and chamber volume is derived. It is found that the reentrant jet causes a reverse flow at the nozzle, which leads to local pressure rise at the same interval. The above research work could contribute to the design and flow control of the ventilated cavity body.

Transient mixed-lubrication and contact behavior analysis of metal liquid film under magneto-thermal effect

To investigate the contact state and interface behavior of the armature-rail (A/R) interface under magneto-thermal shock, this study employs the lubrication theory and considers the coupling effect of electromagnetic and temperature fields. A transient mixed hydrodynamic lubrication model is established using the finite difference method. The study investigates the evolution mechanism of rough surface metal liquid film, electrical contact behavior, and transient mixed lubrication characteristics at the interface under complex magneto-thermal excitation. The study suggests that the electrical contact behavior of the metal liquid film during electromagnetic launch process exhibits significant fluctuation characteristics, which have a crucial influence on the temperature distribution of the metal liquid film. Moreover, due to the fluctuation behavior of electrical contact and factors such as surface roughness, the temperature of the metal liquid film exhibits a complex spatial distribution pattern. The temperature peak continuously increases as the electromagnetic launch progresses. Furthermore, the initially uniform distribution of the metal liquid film gradually transforms into a non-uniform, island morphology due to the joint action of the magneto-thermal effect. However, the liquid metal film still exhibits excellent lubricating properties, which play a crucial role in reducing friction and wear in the electromagnetic launcher system (EMLs).

Advances in Space Launch System Booster Separation Computational Fluid Dynamics

The Space Launch System (SLS) employs two Space Shuttle–derived solid rocket boosters, which separate from the SLS core while still experiencing appreciable aerodynamic loads. Creating an aerodynamic database for this phase of flight can be challenging due to the large number of independent variables needed to fully constrain the problem and the complex flow induced by exhaust plumes of the booster separation motors and core main engines impinging on other parts of the vehicle. This paper details recent efforts in generating aerodynamic data used to create databases for the SLS during the booster separation event using viscous computational fluid dynamics (CFD) simulations obtained using NASA’s FUN3D solver. Particular challenges faced when modeling a complex problem, such as booster separation, are presented. Reductions in interpolation error estimates were observed through the introduction of a physics-based covariance approach to building the CFD run matrix, eliminating infeasible booster location permutations that could potentially skew final response surfaces. Interpolation error control is shown using test cases outside of the main database. Code-to-code comparisons between the FUN3D and OVERFLOW solvers are also presented to further verify the results.

Exhaust Gas and Plume Modeling Effects for Space Launch System Abort Scenarios

Viscous computational fluid dynamics simulations depicting Space Launch System post Mode-1 abort scenarios are conducted and analyzed. The purpose of these simulations is to study the effect of attitude control motor and abort motor plume modeling on the drag of the aborted core stage. The simulations are first conducted with a multispecies and chemically reacting thermodynamic model. Following this, equivalent species are created for the exhaust gases. These equivalent species aim to provide results for core stage drag similar to the chemically reacting model at a lower computational cost. Finally, the exhaust gases are modeled as calorically perfect air. Under most scenarios, both simplified models predict the drag on the core stage close to that predicted by the chemically reacting simulations. In these cases, the flow conditions do not induce significant changes in the composition of the exhaust gas via afterburning. For simulations in which this is not the case, the properties of the simplified models deviate from the true mixture, yielding unsatisfactory results. Finally, the chemically reacting model is weighed against the associated increase in computational costs. The simplified models are at least four times less computationally expensive than the reacting model.

Perbandingan Sistem Levitasi Magnetik Ems dan Eds Untuk Maglev Indonesia

Maglev trains are considered for urban transport and intercity transport systems. On low-medium speed Maglev trains, the operating routine is shorter than that of high-speed trains. Therefore, EMS and LIM technologies are preferred from the point of view of construction costs. However, in high-speed operation, EDS and NGO technologies are preferred for handling, and reliability. In addition, as the development of high-temperature superconductors and new types of permanent magnets develop, stronger and more cost-effective magnetic energy will be used for Maglev trains. The authors believe this technology can be utilized not only for railway applications but also aircraft launch systems and spacecraft launch systems. The need for a new and improved transportation system prompted many countries to be interested and seek to develop Maglev railways. However, although Maglev trains have been studied and developed for approximately half a century, few countries have the knowledge and expertise to do so. This review paper attempts to describe the current complete system in detail and summarizes the basic core technologies of Maglev trains from an electrical engineering point of view. The research hopes to be useful for people interested in this to assimilate Maglev train technology including magnetic levitation, propulsion, guidance, and power supply systems.

Terminal Phase Navigation for AUV Docking: An Innovative Electromagnetic Approach

This study introduces a groundbreaking approach for real-time 3D localization, specifically focusing on achieving seamless and precise localization during the terminal guidance phase of an autonomous underwater vehicle (AUV) as it approaches an omnidirectional docking component in an automated deployable launch and recovery system (LARS). Using the AUV’s magnetometer, an economical electromagnetic beacon embedded in the docking component, and an advanced signal processing algorithm, this novel approach ensures the accurate localization of the docking component in three dimensions without the need for direct line-of-sight contact. The method’s real-time capabilities were rigorously evaluated via simulations, prototype experiments in a controlled lab setting, and extensive full-scale pool experiments. These assessments consistently demonstrated an exceptional average positioning accuracy of under 3 cm, marking a significant advancement in AUV guidance systems.

High-speed scientific spacecraft launches with commercial launch vehicles

Reaching the outer solar system and interstellar space beyond has always been challenging due to the long distances and long travel times. Initial work on planetary gravity assists in the early 1960s by Minovitch and Flandro laid the basis for expanding reachable space with then-existing launch vehicles. Such gravity assists have been key enablers for orbital exploration missions to Mercury (MESSENGER), Jupiter (Galileo, Juno), and Saturn (Cassini-Huygens) by trading higher mass for lower launch energy from Earth (C3). They have also enabled close passes to the Sun (Parker Solar Probe) and moderately rapid solar system escape, coupled with fast flybys of various planetary-sized bodies: Mariner 10 (Mercury via Venus), Pioneer 10 (escape via Jupiter), Pioneer 11 and Voyager 1 (escape via Jupiter and Saturn), Voyager 2 (escape via Jupiter, Saturn, Uranus, and Neptune: the “Grand Tour”), and New Horizons (escape via Jupiter and Pluto). Two of these missions hold the first and second places for the most energetic launches (New Horizons: C3 = 157.7502 km2/s2; Parker Solar Probe: C3 = 152.222 km2/s2). Disadvantages in using Earth and Venus gravity assists to increase spacecraft injected mass to Jupiter and beyond include the time penalty and the need for a customized propulsion system to provide a deep-space maneuver (DSM). For “timely” transits to Neptune with a large orbiter or rapid solar system escape with an Interstellar Probe, more capable launch vehicles can be enabling by pushing the injected mass versus C3 curves “to the right.” While the most extreme speeds asymptotically away from the Sun (7–8 au/yr) can be achieved with fast Jupiter gravity assists and super heavy lift-launch vehicles (SHLLV) such as the Space Launch System (SLS) surmounted by multiple upper stages, solar system escape speeds larger than those achieved by Voyager 1 are possible with existing and upcoming large commercial launch vehicles. Such vehicles include the Falcon-Heavy, New Glenn, and Vulcan Centaur. Better performance accrues with the fully expendable versions of these vehicles and/or with “refilling” in a low-Earth orbit, with performance versus launch cost as a central trade. Even better performance can be projected with SHLLVs in development, such as the Starship Super Heavy and Long March 9. We discuss some of the possibilities and trades such newer vehicles can enable in the near term for continued – and more distant – exploration of the solar system and beyond.

An investigation on coupling analysis and vibration rectification of vibration isolation system for strap-down inertia measurement unit

ABSTRACT The development and deployment of high-precision positioning and orientation systems rely heavily on strap-down inertial measurement units (IMU), which are an integral part of aircraft navigation and launch systems. However, careful study and ongoing use of microelectromechanical systems inertial sensor assemblies (MEMS ISA) present the challenge of vibration disturbances that can significantly degrade the performance of IMU. To alleviate this problem, this paper proposes a vibration isolation system (VIS) based on a motion decoupling mechanism. The designed VIS dynamically decouples 6 degrees of freedom motion, effectively isolating the IMU from external vibrations while allowing free movement, thereby significantly improving control of vibration-induced motion changes. Our approach is validated through finite element simulations and random vibration tests, showing that the proposed VIS effectively reduces transmission measurement errors in IMU. The sensitivity of MEMS ISA to various vibration amplitudes and frequencies can lead to severe vibration correction errors. Therefore, reducing noise and offset is critical for systems that must operate reliably in harsh environments. This study not only explores vibration correction, but also provides a feasible solution through VIS design that can significantly reduce noise and deviation, helping to improve the durability and accuracy of the system. This research is clear that integrating well-designed VIS can significantly improve the resilience and accuracy of MEMS-based inertial systems, paving the way for more robust applications in the aerospace and defense industry.