Launch Platform Research Articles

Investigation of a Tube-Launched Unmanned Aerial Vehicle with a Variable-Sweep Wing

Foldable wings are designed for tube-launched unmanned aerial vehicles (UAVs), aiming to improve portability and meet launch platform requirements. However, conventional tube-launched UAVs cannot operate across the wide speed ranges required for the performance of multiple missions, due to the fixed configuration of their wings after launch. This study therefore proposes a tube-launched UAV which can change wing-sweep angle to expand the flight speed range and enhance the UAV’s agility. A computational aerodynamics method is employed to assess the transient aerodynamic performance of the UAV during the sweep morphing process. The simulation results indicate that the transient aerodynamic forces generate a dynamic hysteresis loop around the quasi-steady data. The lift and drag coefficients exhibit maximum relative deviations of 18.5% and 12.7% from the quasi-steady data for the sweep morphing period of 0.5 s. The hysteresis effect of the flow structure, rather than the additional velocity resulting from wing-sweep morphing, is the major contributor to the aerodynamic hysteresis loop. Compared to the conventional tube-launched UAVs, the proposed tube-launched UAV with a variable-sweep wing shows a wider flight speed range, from 22.59 to 90.12 m/s, and achieves an 82.84% increase in loitering speed. To verify the effectiveness of the wing-sweeping concept, a prototype was developed, and a flight test was carried out. The test data obtained from flight control system agree well with the simulation data, which demonstrates the feasibility and effectiveness of the variable-sweep wing in widening the speed range for tube-launched UAVs. This work can provide a reference for the design of tube-launched UAVs for wide speed range flight.

Motion interval prediction of a sea satellite launch platform based on VMD-QR-GRU

Accurately forecasting the motion of a sea satellite launch platform is crucial for decision support in selecting the optimal launch window and ensuring safety during sea launches. Hence, this paper proposes a novel hybrid prediction model that integrates gated recurrent units (GRU), variational mode decomposition (VMD), and quantile regression (QR) to predict the motion interval of the launch platform. The VMD algorithm effectively captures the multi-scale features of the data, while the QR-GRU model excels in handling nonlinear time series and providing enriched information. Combining the VMD, QR, and GRU leverages their respective strengths, resulting in enhanced prediction accuracy and stability. The experimental data were derived from field measurements of a satellite launch platform during its sea voyage and launch process. By comparing the VMD-QR-GRU model with other models, it was found that the comprehensive metrics for interval prediction of roll and pitch reduced by over 1.4% and 15.7%, respectively. Additional analysis was conducted to evaluate the robustness and transferability of the model, considering various scenarios such as different training data volumes, varying prediction durations, and different states of platform. The VMD-QR-GRU model consistently yielded satisfactory results, underscoring its effectiveness and reliability in predicting sea satellite launch platforms motion.

Robust Trajectory Planning of Gliding-Guided Projectiles with Weak Maneuverability

Due to constraints in launch platforms and cost, the maneuverability of gliding-guided projectiles is limited, necessitating a rational design of their trajectory schemes. To reduce the sensitivity of trajectory schemes to uncertainties while ensuring compatibility between flight schemes and guidance control systems and fully exploiting the control capability of the projectile, a closed-loop robust trajectory planning method is proposed. Models of major uncertain factors and state deviation at the control start point are established. Based on the NIPCE method, the stochastic dynamic model is transformed into a high-dimensional deterministic model with PCE coefficients as state variables, and the uncertainty propagation law is obtained. A PID algorithm is employed to design a tracking guidance law based on position error feedback, and open-loop and closed-loop robust trajectory planning models are established accordingly. The optimal control problem is solved by transforming it into a nonlinear programming problem using the direct shooting method. Our simulation results indicate that the NIPCE method can significantly improve the computational efficiency of uncertainty propagation while ensuring accuracy; compared with parallel MCS, the computation time is reduced by 96.8%. Open-loop robust planning can effectively mitigate the sensitivity of gliding trajectories to uncertainties (the standard deviations of terminal altitude and lateral deviations are reduced by 23.6% and 35.3%, respectively, compared to deterministic planning) but cannot completely eliminate terminal dispersion. Closed-loop robust planning effectively improves control effort consumption on the basis of open-loop planning.

Earmuff performance in the presence of high-level impulse from a recoilless weapon firing in a confined space.

A noise attenuation performance test was conducted on earmuffs using a recoilless weapon launch platform in a confined space, along with two acoustic test fixtures (ATFs). The overpressure at the ATF's effective tympanic membrane comprised direct sound at 185 dB sound pressure level (SPL) and reflected sound at 179 dB SPL. Wearing earmuffs reduced these peaks to 162 dB SPL and 169 dB SPL, respectively. The reflected sound from walls was defined as delayed sound. An analytical model for earmuff noise attenuation simulated their effectiveness. The simulation revealed that when the earmuffs attenuated delayed sound, the acoustic impedance of acoustic leakage and the acoustic impedance of the earmuff material decreased by 96% and 50%, respectively. The negative overpressure zone between direct and delayed sound decreased the earmuffs' fit against the ATF. Additionally, the enclosed volume between the earmuff and the ear canal decreased by 12%. After the installation of bandages on the earmuffs, the overpressure peak of delayed sound was reduced by 5 dB. Furthermore, the acoustic impedance of the earmuff's sound leakage path and the acoustic impedance of the earmuff material deformation path increased by 100% and 809%, respectively.

Experimental study of scaled-down model ejection water ballistics and two-phase flow of gas and water

There are many factors affecting the hydrodynamic and water ballistic trajectory of vehicles launched underwater, among which the ejection gas pressure, initial motion parameters of the submarine launch platform and the launching water depth have a particularly significant influence. Since it is costly and too long time to carry out a real-size study on the influence of underwater launching parameters, this paper adopts a scaled-down model ejection test to study the evolution characteristics of the flow field of vehicle launched underwater with different ejection pressures and initial ejection angles to reveal the influence of the above parameters on the characteristics of the water ballistics.

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.

Development of a Novel Measurement Setup to Study and Predict Electrostatic Discharges in Agitated Glass‐Lined Vessels

AbstractTwo glass lined reactors in a launch platform facility operated by Syngenta have been damaged during the crystallization of an organic compound due to electrostatic discharges. The goal of this work was to design and commission a novel setup to measure charges and currents generated by this slurry in a laboratory‐scale reactor. An improved and more sophisticated setup was then proposed for possible implementation in Syngenta's own laboratories. With this novel setup, the electrostatic charging of stirred suspensions involving nonconductive solvents could be accurately measured in the context of a case study that involved the suspension that led to liner damages in the production facilities of Syngenta.

XFEM-Based Study of Fatigue Crack Propagation in Rocket Deflector Troughs under Coupled High-Temperature and Impact Conditions

This research investigated fatigue crack propagation on the lower surface of rocket deflector troughs in offshore rocket launch platforms. Initially, a numerical model of an offshore rocket launch platform was established using ABAQUS based on the Extended Finite Element Method (XFEM). Subsequently, two variable parameters—the initial crack length and initial tilt angle—were introduced. This research systematically analysed the impact of these parameters on the fatigue crack propagation patterns in both the maximum stress and maximum deformation regions of the deflector channels under the combined conditions of high temperature and impact. Finally, the research indicated that the propagation length of surface cracks in the deflector trough exhibited an initial increase followed by a decrease with the rise in the pre-set inclination angle. Notably, the stable propagation rate of the crack in the region of maximum deformation surpassed that observed in the region of maximum stress. Through meticulous comparative analysis, it was evident that temperature loading significantly exacerbated the initiation and propagation of cracks, particularly in the upper region of the deflector channel’s lower surface.

Why Digital Platforms by Incumbents Fail: Results from a Delphi Study

In an economy increasingly dominated by digital platforms, incumbent firms are trying to launch platforms associated with their original products in an attempt to remain relevant and create additional value propositions. Yet, evidence shows that digital platform design from within a non-digital product company is not straightforward and many failures have been observed. As previous research is scarce to explain the root causes of this lack of platform success, we conducted a Delphi study with global experts in the automotive industry to identify those factors that can explain why these incumbents are failing with their digital platform initiatives. We identified six categories that complement the established body of knowledge on failure factors with digital platforms. Based on that, we suggest an integrative framework to explain typical failures in digital platforms by incumbents.

Dual observers based adaptive fuzzy output feedback control of a motor-driven launching platform with input saturation and disturbance rejection

In this paper, the high accuracy motion output feedback control of a kind of launching platforms driven by motors is focused. The launching platform is used to launch kinetic load to hit the target so it is susceptible to external disturbance. In addition, significant issues arise due to limitations on the plant inputs, such as actuator energy limits and velocity state is usually unavailable due to the limitation of system cost and volume. A new adaptive fuzzy output feedback controller based on dual observers is proposed for solving these problems. A smooth and continuous model is established for input saturation to compensate it. A sliding mode observer and a fuzzy observer with proper membership function are combined to estimate the unmeasured system states more accurately. An adaptive robust controller and the fuzzy observer are combined to realize a motion control with disturbance rejection, which allows correct adaptation while the plant input is saturated. Lyapunov theorem proves the bounded stability of the proposed controller when there exists observation error. Extensive comparative simulation and experiment results verify the effectiveness and practicability of the proposed controller and show that the control accuracy can be improved by an order of magnitude compared with the traditional PID controller and better than some other nonlinear controllers.

Cavity evolution of ventilated vehicle launch under a rolling condition

The unsteady development of the tail cavity of a vehicle after it leaves a tube often causes adverse effects, most notably an impact load on the vehicle when the cavity ruptures. The rolling of the launch platform can alter the development of the tail cavity, significantly altering the influence of the impact load on the motion and attitude of the vehicle. The present study employs the shear stress transport k-w model, the volume of fluid multiphase flow model, the Schnerr–Sauer cavity model, and the overlapping mesh technique to conduct numerical simulations of the underwater launching process of a ventilated vehicle under both stationary and rolling boundaries. A comparative analysis is conducted to examine the evolution of the cavity shape, pressure distribution, and collapse-induced load in the tail cavity under various conditions after vehicle launch. The findings suggest that the rolling of the tube induces an asymmetrical development of the shoulder cavity lengths and widths on both the windward and leeward sides, with the result of a lower peak pressure at the cavity closure position compared with that under stationary conditions. The rolling of the tube reduces the internal velocity within the tail cavity, elevates the rupture position of the tail cavity, delays the tail cavity rupture, impacts the timing of the force peak occurrence in the vertical direction of the vehicle, reduces the high pressure at the point of tail cavity rupture, and modifies the post-rupture structural characteristics of the tail cavity.

Deflector shape impact on aero-acoustic noise generation and propagation

The acoustic pressure level generated during lift-off and the associated vibrations can significantly affect the payload of a launch vehicle. Optimizing the plume deflector is one of the most effective methods to reduce this noise. Considering the Vega launcher as a case of study, different deflectors are studied: flat, inclined at 30°, and wedge. The approach followed is to use the unsteady Navier–Stokes equations to solve both the noise generation and the propagation. First, it has been observed that the blast wave, due to the ignition overpressure, is independent of the deflector geometry. However, the predominant acoustic waves are due to the impact of the jet with the deflectors. The analysis has shown that the flat deflector generates more shock waves and propagates the acoustic waves equally in all directions so that more acoustic loads reach the fairing. The inclined deflector causes a plate shock and intermediate tail shocks and redirects the flow towards one side of the launcher. Finally, the wedge deflector generates a detached shock wave with a higher pressure increase than the inclined deflector. However, as the flow is redirected towards the two sides, a lower OASPL reaches the fairing. In the same way, the pressure distribution over the fairing surface has shown that the wedge deflector is acoustically more efficient for this case of study. The acoustic effectiveness of deflectors has been demonstrated compared to the case without a deflector. Therefore, deflectors are advised to be included on the launch platform to improve payload comfort and reliability on the launchers.

Game Theory in Companies: A Program-approach to Find all Nash equilibria in Games with Two Players

Game theory is a famous mathematical formula for economic decision-making. When two companies launch competing games within a similar time frame in the game industry, they must choose wisely between launch dates, trailer release dates, and launch platforms to seek the highest return and lower risk. This report turns the three main strategies of the release time, the preview time, and the release platform into specific values and finds the optimal strategy choice using nash equilibria. Nash equilibrium is an essential concept in finding the optimal solution. Given the complexity of finding the equilibria, computational tools are used for the task. Software like Gambit, Game Theory Explorer and python programs are used for computing all nash equilibria. This paper quantifies the three main reasons that may affect the sales result: the timing and order of the trailer, the interval between launch days, and the release platform, and turning these factors into a pay-off matrix. According to the calculation results on those pay-off matrices, this paper formulates a set of well-founded game sales methods to maximize the company's profits.

LoRa-Based Low-Cost Nanosatellite for Emerging Communication Networks in Complex Scenarios

Wireless broadband coverage has reached 95% worldwide. However, its trend is expected to stay the same in the following years, presenting challenges for scenarios such as remote villages and their surrounding environments. Inaccessibility to these areas for installing terrestrial base stations is the main challenge to bridge the connectivity gap. In addition, there are emergencies, for instance, earthquakes or war areas, that require a fast communication reaction by developing networks that are less susceptible to disruption. Therefore, we propose a low-cost, green-based nanosatellite system to provide complete coverage in hard-to-reach areas using long-range communication. The system comprises a pilot station, a base station, and a CubeSat with sensor data collector capabilities acting as a repeater. Our system can be built within hours with a 3D printer using common material, providing a flexible environment where components can be replaced freely according to user requirements, such as sensors and communication protocols. The experiments are performed in Spain by two test sets validating the communication among all components, with RSSI values below −148 dBm and the longest distance above 14 km. We highlight the reduction in the environmental impact of this proposal using a balloon-based launch platform that contributes to sustainable development.

Numerical Exploration of Low Altitude Rocket Plume in Aircraft Vicinity

Low altitude plume of a solid rocket motor is numerically explored. The effects of free stream Mach number, altitude and presence of launch platform wing on plume shape are studied. Three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations along with k-ε turbulence model and species transport equations are solved using commercial CFD software CFX-11. Thermochemical parameters (Mach number, pressure, temperature and propellant hot gas mass fraction) are analysed to characterize the plume. Mixing layer boundaries, its thickness and the attainment of self-similarity are evaluated to study the plume structure. With the increase of free stream Mach number, the computed plume diameter reduces. Centerline pressure, temperature and radial expansion of the plumes increases with the increase in altitude. Plume is found to be elongated and narrowed with relatively warm core region due to the presence of platform wing.

Numerical simulations of seawater spraying on launch platform during CZ-8X offshore launching

In this paper, the cooling effect of seawater spraying on the offshore launching platform used by the CZ-8X rocket at different takeoff heights is studied. The rocket plume model using the realizable k- ε turbulence model is established, which is based on the three-dimensional Navier-Stokes equations. The injected seawater for cooling the deck surface is described by the Eulerian dispersed phase (EDP) model. The numerical results are compared with the experimental data in the literature to verify the validity and accuracy of the numerical model. The coupled flow field of the CZ-8X rocket plume and seawater at different takeoff heights and different spray velocities are simulated. The results show that the thermal environment on the deck surface of the platform is the worst when the takeoff height reaches 30 m. The seawater spraying velocity shall be moderate before the takeoff height reaches 30 m. A low spraying velocity will lead to poor cooling effect on deck surface, and a high spraying velocity could lead to increased diffusion of plume flow in non-spraying direction. After the takeoff height rises to 40 m, a low water spraying velocity makes the injection position of seawater far away from the jet core area, and the seawater evaporation rate is low, which is conducive to the accumulation of seawater layer on the deck surface. The cooling effect of thermal barrier layer is very obvious. The research shows that when the rocket is launched at sea, the launch platform can be cooled by pumping and spraying seawater, and the water spraying rate can be adjusted appropriately according to the takeoff height to achieve the best cooling effect.

Characterization Method of Damage Information Based on Heterogeneous Network.

Damage is the main form of conflict, and the characterization of damage information is an important component of conflict evaluation. In the existing research, damage mainly refers to the damage effect of a damage load on the target structure. However, in the actual conflict environment, damage is a complex process that includes the entire process from the initial introduction of the damage load to the target function. Therefore, in this paper, the transfer logic of the damage process is analyzed, and the damage process is sequentially divided into being discovered, being attacked, being hit, and being destroyed in succession. Specifically, first considering the multiple types of each process, the transmission of damage is likened to the flow of damage, a network model to characterize damage information based on heterogeneous network meta-path and network flow theory (HF-MCDI) is established. Then, the characteristics of damage information are analyzed based on the capacity of the damage network, the correlation of the damage path, and the importance of the damage node. In addition, HF-MCDI can not only represent the complete damage information and the transmission characteristics of the damage load but also the structural characteristics of the target. Finally, the feasibility and effectiveness of the established HF-MCDI method are fully demonstrated by the example analysis of the launch platform.

Dynamics simulation of folding wing UAVs launched from a high-altitude balloon platform

It is a new application of the high-altitude balloon system to launch multiple small folding wing unmanned aerial vehicles (UAVs). Based on the design of the launching system, we conduct numerical simulations of the ejection process from the balloon platform and the subsequent UAV wing deployment with trajectory leveling operation. We use the Kane method to establish the dynamic model of the balloon launching platform in the inertial coordinate system (ICS). By introducing the degree of freedom of UAV sliding along the sliding track, we realize the dynamic simulation of eight UAV launching processes and obtain the instantaneous separated states. The folding wing UAV first deploys its wings after ejection, which has the coupling characteristics between structural deformation and attitude adjustment. It is regarded as a multi-rigid body connecting structure composed of the fuselage and four wings. We establish the dynamic simulation model by the Kane method in the UAV body coordinate system (BCS). The Radau pseudo-spectral method is used to calculate the flight trajectory of each UAV. This paper is an engineering application research and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV program.

Experimental study on impact response of seaborne rocket launch platform

This paper presents a novel test method for evaluating the impact response of a seaborne launch platform. By simulating and analyzing the platform's impact response to develop a test plan, designing an assistive test device to enhance data accuracy, and conducting a shipboard test, we analyzed the launch platform's impact response during cold launch. Results show that during the ejection stage, the platform experiences a sudden acceleration peak that quickly attenuates. During ignition, the vibration acceleration response oscillates and fluctuates. The maximum structural impact response occurs below the launcher, gradually attenuating to the bow, stern, and sides of the ship, and propagating slowly along the captain's direction. The vibration acceleration response varies along different directions, with the highest response in the vertical direction and the lowest in the longitudinal direction. FE numerical analysis confirms the experimental results. This study provides reference data for the structural anti-impact design of seaborne launch systems.

Dynamic Simulation and Research of Land-Based Missile Tilt Launch Platform

In order to study the influence of the structural factors of the launch device on the missile tilt projectile dynamics, a dynamic model of the missile tilt launch platform was established based on the finite element method. The effects of shock absorber stiffness, angle between shock absorber and horizontal plane and tilt of the launch device were studied on the missile and launch platform’s ejection response characteristics. The research results show that the greater the rigidity of the shock absorber, the smaller the angle between the shock absorber and the horizontal plane, and the smaller the vibration amplitude of the initial disturbance of the missile and the launch cylinder; when the tilt angle of the launch device is within 6 °, the angle change has a smaller impact on the speed of the missile outlet, and there is a sufficient safety distance between the missile and the launch canister during the launch process. The larger the vibration amplitude of the initial disturbance and the launch tube. The research results can provide a theoretical reference for the design and optimization of the tilted launch platform.