Heavy Lift Launch Vehicle Research Articles

Online prediction of joint mechanical properties of FSW thick AA2219-T8 based on multi-source information fusion using 1DCNN

High strength AA2219-T8, Al-Cu alloy of 18 mm plate is welding by friction stir welding (FSW) technology and used for heavy-lift launch vehicles tank. During FSW thick AA2219-T8 plate, joint tensile strength and microhardness are affected by multiple interconnected variables including welding force, temperature, and geometric quantity of the butt face. The joint mechanical properties are difficult to predict and ensure. This paper proposed a hybrid predicting approach based on multi-source information fusion, called Down-Sampling and One-Dimensional Convolutional Neural Network (DS-1DCNN). Initially, FSW experiments were conducted to collect the axial force, welding surface temperature at advancing and retreating side, gap, and mismatch signals, which were fused through DS technology. To extract temporal information and features from signals, a 1DCNN prediction model was established, with the fused multi-source signals as input and the tensile strength and Vickers hardness as output. Subsequently, the optimal model architecture and hyper-parameters of 1DCNN were determined through experiments and grid search combined with K-fold cross-validation, and an online prediction system was developed. Finally, effective validation experiments were conducted and the experimental results agreed with the DS-1DCNN prediction results with an acceptable error of approximately 5%. Parameter sensitivity analysis revealed that the number of convolutional layers and learning rate were identified as critical parameters affecting the model performance. Additionally, time analysis showed that the calculation time of the prediction system was less than 200 ms which can meet the time requirements of real-time thick-plate FSW application. The research lays a foundation on the real-time quality monitoring in the process of FSW thick-plate butt joint.

Alleviation of SWBLI over the payload of a launch vehicle by change of nose shape

Wind tunnel tests on a typical heavy-lift launch vehicle configuration featuring a core vehicle flanked by two strap-on boosters showed very high levels of unsteady pressures over the payload region at transonic Mach numbers when the nose had a cone-cylinder shape. This was due to very high levels of Shock Wave Boundary Layer Interactions (SWBLI) associated with the conical shape, which caused alternating flow featuring the formation of a unsteady λ-shock system over the payload region and a pair of counter-rotating vortices. The phenomenon was found to strongly depend on the proximity of the noses of the strap-on boosters to the boat tail downstream of the payload region. When the conical nose was replaced by an ogive-shaped nose, significant reduction in SWBLI occurred, with dramatic reduction of shock oscillations, pressure fluctuations, replacement of alternating flow by steady flow and disappearance of the vortex-pair. Time-averaged pressure fluctuations indicate reduction in pressure gradients due to a more gradual expansion of flow over the ogive nose compared to conical nose, an observation also supported by CFD simulations. The alleviation of SWBLI with ogive nose was so effective that the presence or absence of strap-on boosters had practically no effect on pressure fluctuations over the payload region. Unlike the conical shape, the ogive nose cone shape seems to meet both the shape and pressure parameter-criteria of NASA to ensure buffet-free environment.

Sound power of NASA's lunar rockets: Space Launch System versus Saturn V.

To improve acoustical models of super heavy-lift launch vehicles, this Letter reports Space Launch System's (SLS's) overall sound power level (OAPWL) and compares it to NASA's past lunar rocket, the Saturn V. Measurements made 1.4-1.8 km from the launchpad indicate that SLS produced an OAPWL of 202.4 (±0.5) dB re 1 pW and acoustic efficiency of about 0.33%. Adjustment of a static-fire sound power spectrum for launch conditions implies Saturn V was at least 2 dB louder than SLS with approximately twice the acoustic efficiency.

Ongoing analysis of far-field acoustical measurements during the Artemis-I launch

As the global space industry expands, impacts from super heavy-lift launch vehicle noise on payloads, communities, and natural habitats are better understood with improved source models. To support model development, this paper discusses ongoing analyses of far-field acoustical measurements made during the NASA Space Launch System (SLS) Artemis-I mission. Fifteen acoustical measurement stations were deployed prior to the launch, including ten autonomous stations within Kennedy Space Center and five manned stations off-Center, up to 50 km from the pad. This paper presents a brief summary of data analyzed from all 15 stations, including A-weighted and unweighted sound pressure levels and spectra. Additionally, the skewness of the pressure time derivative is shown as a quantifier of the noise’s crackling component. Finally, source directivity and sound power analyses are presented. [Work supported in part by the NSF REU Program and the Utah Space Grant Consortium.]

Quantized predefined-time control for heavy-lift launch vehicles under actuator faults and rate gyro malfunctions

The quantized control problem for a heavy-lift launch vehicle (HLV) under actuator faults and rate gyro malfunctions is addressed in this paper. A predefined-time observer (PTO) is designed to reconstruct the immeasurable time derivative of attitude tracking errors with the settling time precisely predefined by one design parameter. Thus, parameter tuning for temporal demands is more straightforward and less conservative for the PTO than for fixed-time observers. Using the reconstructed state, a quantized controller is developed to render attitude tracking errors to a small neighborhood of the origin within a predefined time interval (physically realizable) under actuator faults. The controller has three characteristics (1) An unswitched singularity-avoidance layer is derived to ensure the boundedness of control signals. (2) A hysteresis quantizer is used to discretize control signals for applications on the digital onboard platform and reduce communication burden. (3) The settling time of attitude tracking errors is predefined by two design parameters under discretized control signals without using performance functions, avoiding the risks of violating performance functions and sudden controller collapse suffered by the existing quantized predefined-time controllers. Furthermore, stability analysis is impelled using a nonsmooth analysis method and a Lyapunov method. Finally, numerical simulations on an HLV demonstrate the efficiency of the proposed control system.

LARGE-SCALE REDUCTIONS IN THE ELECTRON DENSITY OF IONOSPHERIC F-REGION, OBSERVABLE ALONG ROCKET TRAJECTORIES AT LAUNCH

Purpose. The object of the study are electron density depletions (‘holes’) occurring in the ionospheric F-region under the action of rocket exhaust products. The purpose is to present and discuss the results of observations concerning the ionospheric holes that were detected in the course of a number of launches of medium-lift Kosmos vehicles from the Kapustin Yar spaceport. Nei- ther that cosmodrome, nor the rocket type had been subjects of similar analysis before. Design/methodology/approach. The observations at the Kapustin Yar cosmodrome were performed with a portable vertical Doppler sounder. The beats between a reference signal and the one reflected from the ionosphere were subjected to spectral analysis, which allowed identifying the principal mode of the Doppler frequency shift and establishing time dependences of that frequency shift. An ionosonde located nearby was used for monitoring the underlying state of the ionosphere. Findings. The measurements performed with the vertical Doppler sounder near the launch site of the medium-lift Kosmos rocket have allowed obtaining first estimates for the principal parameters of the ionospheric holes arising in the F-region along the vehicle trajectory, as well as for the accompanying quasi-periodic variations in the electron density. The spatial scale sizes of the holes have been found to be in excess of 300 km, while the electron density reductions may attain » 50 %. These results are in agreement with the data obtained by international researchers for effects from heavy- and super heavy-lift launch vehicles. Also, note that the types of propellant differed significantly. The propagation velocity of the hole’s front edge was estimated to be » 140 m/s. The hole formation was accompanied by quasi-periodic variations in the Doppler frequency shift as a result of radar signal scattering from the electron density fluctuations produced by propagating atmospheric gravity- and infrasonic waves. The atmospheric gravity waves showed periods in the range from 7 to 20 minutes, and the infrasonic waves had a period close to 2 min. The amplitudes of quasi-periodic electron density variations were estimated for the two modes to be » 0.3 ¸1.5 % and » 0.02 ¸ 0.03 %, respectively. Conclusions. Medium-lift launch vehicles (mass of a few hundred tons) are capable of forming ionospheric ‘holes’ of several hundred kilometers in size and of reducing the electron density in the F-region by a factor greater than 2.

Анализ возможностей создания беспересадочных систем экстренной эвакуации с высотных агрегатов стартовых комплексов ракет космического назначения

When fueled integrated launch vehicles are prepared for a launch, there is an increased risk of fires and explosions due to fuel and oxidizer on board these vehicles. Therefore, it is necessary to ensure emergency evacuation of manned spacecraft crew and assisting personnel in dangerous situations. For vehicle service towers or crew embarkation and evacuation units this is quite a challenge as the spacecraft is at high altitude, especially it is difficult when preparing super heavy-lift launch vehicles. To solve this problem, special evacuation systems of various types are used. A common feature of existing systems for emergency evacuation from high-altitude units is the need to transfer from the main means of evacuation to an armored personnel carrier or to shelter behind the doors of a proteсted accommodation, which reduces the reliability and increases the cost of the system, especially in operation. The paper explores the prerequisites and opportunities for developing crew embarkation and evacuation systems without the use of protected accommodations and transfers, which can potentially reduce the cost and increase the reliability of these systems.

Influence of Mesh Density on Repeatability of FSW Process Simulation Based on DEFORM

To solve the problem of the relative error caused by mesh density is difficult to quantitatively evaluate, a process simulation model of FSW (friction stir welding) 2219 aluminum alloy is built based on DEFORM. Process simulation models with different mesh densities are solved, the influence of mesh density on simulation repeatability and time-consuming is analyzed, and the mesh density suitable for the process simulation model is determined. The evaluation method proposed offers a theoretical reference for the determination of local optimal mesh density of the FSW process simulation model based on DEFORM. This study provides a basis for high precision prediction and characterization of the temperature distribution of FSW on heavy-lift launch vehicle fuel tank.

Experimental investigation on the temperature and pressure characteristics of supercritical helium for liquid hydrogen pressurisation

Liquid hydrogen is a good energy storage medium for heavy-lift launch vehicles owing to its high energy density. A suitable pressurisation system is required when liquid hydrogen is injected into the combustion chamber from the storage tank. Helium has the advantages of stable properties and low density. Therefore, when it is used for liquid hydrogen pressurisation in heavy-lift launch vehicles, the weight can be greatly reduced. An experimental setup for supercritical helium natural convection heat transfer for liquid hydrogen pressurisation was established in this work, and the temperature and pressure characteristics during the processes of filling with liquid nitrogen, filling with helium, heating, and repeated heating were analysed based on the setup. The results showed that the cooling rate during the cooling process in the experimental cavity filled with helium was mainly dependent on the distance between the measuring point and the inner wall of the cavity, but not on the height. The heating rate in the upper part of the cavity was the fastest during the process of filling with helium as the supercritical helium with higher temperatures accumulated in this region. The pressure in the cavity substantially affected the dynamic characteristics of the temperature and pressure of the supercritical helium during the heating process. The pressurisation efficiency was increased by approximately 4.6 times when the initial pressure was increased by 7 times. The results are helpful for improving the liquid hydrogen energy storage efficiency, as well as realising a safe and efficient pressurisation of liquid hydrogen.

General Scheme and Key Technology of Long March 5 Launch Vehicle

Long March 5 (LM-5) is a new generation of heavy-lift launch vehicle developed by China. It has successfully completed the first Mars exploration of China and the 3rd phase of China lunar exploration program of Chang’E 5 (CE-5). LM-5 experienced 30 years of key technology research and engineering development. During this period, a lot of engineering technical problems were conquered, rich experience in the development of large cryogenic launch vehicle was accumulated, and the development of the new generation launch vehicle system was constructed. The research capability and foundation of carrier rockets have been greatly improved. This paper describes the development background of LM-5. Based on the overall rocket technical scheme and technical innovation, this paper discusses the development thinking of the rocket, the modular configuration scheme, the overall optimization design technology of the whole rocket and the structure technology of the large diameter and large concentrated load rocket body, and probes into the key technical problems of the LM-5 for the deep space exploration mission, specifically, the orbit design and optimization technology for deep space exploration mission, and narrow window multi-orbit launch technology. LM-5 is a landmark project of China’s new generation of launch vehicle, representing the highest level of launch vehicle technology of China, and is a significant symbol for China’s transformation from a major player in space to major power in space.

Ascent control of heavy-lift launch vehicle with guaranteed predefined performance

In this paper, the problem of ascent attitude tracking control is studied for a heavy-lift launch vehicle (HLV) with guaranteed predefined performances. Firstly, the attitude tracking error dynamics model is developed by using a second-order reference model which can guarantee the expected overshoot and steady-state error. Subsequently, a novel prescribed performance function (PPF) is proposed with a predefined convergence time, and an error transformation method with tangent function is developed. Moreover, by utilizing this PPF structure, a predefined performance attitude tracking error dynamics model is proposed. Based on the predefined-time stable theory, an adaptive predefined-time sliding mode controller with adaptive gain control law is presented and the convergence time can be defined as a prior control parameter, simultaneously. Stability of the proposed controller and the adaptive gain control law are proved by the Lyapunov method. Finally, abundant simulation results verify the predefined performance of the proposed control method.

Обоснование выбора точек подвеса транспортно-установочной тележки канатами механизма подъема на стартовых комплексах

The paper considers the problem of selecting the optimal weight and size characteristics of an erector frame for advanced super heavy-lift launch vehicle by selecting the suspension points of lifting mechanism ropes to the erector when transferring the rocket to a vertical position at the launch complex. The calculated dependences of frame weight and the force in polyspast system on the distance between the points of erector attachment to the racks of the launch pad and the points of erector suspension with the ropes are presented. The effect of the transverse width of the erector frame guide beams and the angle between the tight ropes and the horizon at the initial moment of lifting the rocket to the vertical position on the weight and dimensions of the erector is analyzed. According to the calculation results there is the possibility of a significant reduction in the weight, size and cost of the erector and the drives of lifting mechanisms in comparison with the case when ropes are attached to the cantilever part of the frame and systems using hydraulic drives as the lifting end organs of the erector beam.

Fuel Conservation for Launch Vehicles: Falcon Heavy Case Study

Space exploration has recently been growing at an increasing pace and has caused a significant burden to the environment, in particular, during the launch of rockets, when a large amount of fuel is burned and the exhaust gases are released in the air. For this case study, we selected the SpaceX Falcon Heavy reusable heavy-lift launch vehicle, which is one of the most promising rockets for the low-cost lifting of heavy payloads into orbit and beyond. We evaluated several strategies for optimisation of fuel consumption and for minimisation of environmental impact during launch through the atmosphere for the case of its first launch on February 6, 2018, when the rocket carried a red Tesla Roadster with a “Starman” in the direction toward Mars. In addition to the flight plan and Newtonian equations of motion, we have taken into account the thermodynamic properties of the rocket engines. Results are similar but slightly different if one minimises the total fuel consumption for the desired flight plan or if one minimises the environmental pollution during the initial stage of the launch through the atmosphere. The same methodology can be extended for launches in other directions including the Earth orbit and the Moon.

Multi-channel wireless sensor network for Heavy-Lift Launch Vehicles

A typical new generation Heavy-Lift Launch Vehicle (HLV) has more than 600 sensors on board. More than 80% of these sensors are used for non-critical operational and technological data. This data is sent to the ground launching controllers allowing them to supervise, in real time or a posteriori, information concerning the state of the HLV and the progress of the launching operation. Sensors are traditionally connected to a concentrator entity using cables. The concentrator is a special node in charge of collecting data that is generated by sensors and transmit it to the ground controllers unit. The use of wireless technology to interconnect sensor nodes with the concentrator would allow an ease of deployment and a weight gain which will help achieve assembly time reduction and a gain in terms of generated power. Nevertheless, of-the-shelf wireless technologies cannot guarantee a wired equivalent reliability in terms of packet delivery ratio or end-to-end delay. Indeed, when transmitting over wireless communication links it is challenging to find a solution that avoids data loss especially in high data rate scenarios. This is essentially due to the nature of the wireless medium that is very sensitive to the surrounding environment and to the possible simultaneous multiple accesses to the medium by the different sensor nodes. In this paper, we propose a wireless solution based on the physical layer of IEEE 802.15.4 standard in the 2.4 GHz frequency band that enhances packet delivery ratio under an acceptable end-to-end delay threshold during all phases of the launching operation. The proposal is a multi-channel and multi-hop protocol that allows sensors that are deployed close to the interstage of the HLV to communicate with a multi-radio interface concentrator node. Simulation results show promising performance in terms of packet delivery rate and end-to-end delay.

Proper-Orthogonal-Decomposition-Based Buckling Analysis and Optimization of Hybrid Fiber Composite Shells

Composite cylindrical shells have been widely used in the fuel tanks of launch vehicles. To reduce the material cost of carbon-fiber-reinforced polymer shells, hybrid fiber composite shells composed of carbon fibers, glass fibers, and an epoxy matrix would be a more promising choice. Along with the development of heavy lift launch vehicles, the diameter of a required shell structure could become large. The buckling analysis of composite shells based on detailed finite element models was too time consuming. From the point of view of model size reduction, accurate reduced-order models for buckling analysis along with optimization methods were needed to improve the efficiency of the design and analysis cycle of composite shells. A combined proper orthogonal decomposition and optimization method is proposed in this paper for an efficient buckling analysis of composite shells. In the offline steps of proper orthogonal decomposition, one single finite-element-model buckling analysis is performed based on a full-order model of the initial design with the certain volume fractions of hybrid fibers. Furthermore, snapshots generated from the eigenvector values of the finite-element-model buckling analysis result from the initial design, and a proper orthogonal decomposition basis is determined. By using the obtained proper orthogonal decomposition basis from the initial design, the online steps of proper orthogonal decomposition can be carried out for the buckling analysis of any composite shell with varying volume fractions of hybrid fibers. To further improve the prediction accuracy for a large design space, the mixed proper orthogonal decomposition snapshot method is proposed by adding additional proper orthogonal decomposition snapshots into the original ones. The proposed method contributes to improving the prediction accuracy among the entire design space significantly. Finally, a low-cost optimization framework is established for hybrid fiber composite shells, during which the proper orthogonal decomposition method is used for accelerating the buckling analysis. In particular, a convergence criterion and an updated proper orthogonal decomposition basis strategy are proposed for the optimization framework, aiming at guaranteeing the credibility of the optimal proper orthogonal decomposition buckling result. By means of an illustrative example, the effectiveness and efficiency of the developed framework are demonstrated.

Planetary defense mission concepts for disrupting/pulverizing hazardous asteroids with short warning time

This paper presents an overview of space mission concepts for disrupting or pulverizing hazardous asteroids, especially with warning time shorter than approximately 10 years. An innovative mission concept, referred to as a nuclear hypervelocity asteroid intercept vehicle (HAIV) system, employs both a kinetic-energy impactor and nuclear explosive devices. A new mission concept of exploiting a multiple kinetic-energy impactor vehicle (MKIV) system that doesn’t employ nuclear explosives is proposed in this paper, especially for asteroids smaller than approximately 150 m in diameter. The multiple shock wave interaction effect on disrupting or pulverizing a small asteroid is discussed using hydrodynamic simulation results. A multi-target terminal guidance problem and a planetary defense mission design employing a heavy-lift launch vehicle are also brie y discussed in support of the new non-nuclear MKIV mission concept. The nuclear HAIV and non-nuclear MKIV systems complement to each other to effectively mitigate the various asteroid impact threats with short warning time.

Межорбитальная транспортная система с Лунным экспедиционным комплексом, собираемым на низкой околоземной орбите с использованием ракет-носителей тяжелого класса

Межорбитальная транспортная система с Лунным экспедиционным комплексом, собираемым на низкой околоземной орбите с использованием ракет-носителей тяжелого класса

In-orbit assembly mission for the Space Solar Power Station

The Space Solar Power Station (SSPS) is a large spacecraft that utilizes solar power in space to supply power to an electric grid on Earth. A large symmetrical integrated concept has been proposed by the China Academy of Space Technology (CAST). Considering its large scale, the SSPS requires a modular design and unitized general interfaces that would be assembled in orbit. Facilities system supporting assembly procedures, which include a Reusable Heavy Lift Launch Vehicle, orbital transfer and space robots, is introduced. An integrated assembly scheme utilizing space robots to realize this platform SSPS concept is presented. This paper tried to give a preliminary discussion about the minimized time and energy cost of the assembly mission under best sequence and route This optimized assembly mission planning allows the SSPS to be built in orbit rapidly, effectively and reliably.

Numerical-based smeared stiffener method for global buckling analysis of grid-stiffened composite cylindrical shells

With regard to future heavy-lift launch vehicles, the buckling analysis and optimization of large-scale stiffened shells by finite element method (FEM) suffer from unbearable computational cost. In spite of the high analysis efficiency, the traditional smeared stiffener method (SSM) is still not accurate enough owing to the assumptions of analytical derivations. In this study, an effective and efficient numerical-based smeared stiffener method (NSSM) is proposed for the buckling analysis of stiffened shells. Firstly, the representative unit cell of stiffened shell is divided, and then it is equivalent using a novel numerical implementation of asymptotic homogenization (NIAH) method. The equivalent stiffness coefficients can be obtained accurately. Then, the buckling load is calculated by means of Rayleigh–Ritz method. Comparing with the prediction results of SSM and FEM, the high prediction accuracy and efficiency of NSSM are observed. Then, the effectiveness of NSSM for different loading conditions and model scales are discussed. Finally, numerical examples illustrate the high prediction accuracy and widespread applicability of NSSM for various grid-patterns, and the advantage of the rotated triangle grid-pattern in load-carrying capacity among various grid-patterns is demonstrated.

Computational framework for Launch, Ascent, and Vehicle Aerodynamics (LAVA)

The Launch Ascent and Vehicle Aerodynamics (LAVA) framework, developed at NASA Ames Research Center, is introduced. This technology originated from addressing some of the key challenges that were present during the re-design of the launch infrastructure at Kennedy Space Center. The solver combines Computational Fluid Dynamics (CFD) capabilities with auxiliary modules, such as Conjugate Heat Transfer (CHT) and Computational Aero-Acoustics (CAA). LAVA is designed to be grid agnostic, i.e., it can handle block-structured Cartesian, generalized curvilinear overset and unstructured polyhedral grids either as stand-alone mode or by coupling different grid types through an overset interface. A description of the spatial discretizations utilized for each grid type, along with the available explicit and implicit time-stepping schemes, is provided. The overset grid coupling procedure for Cartesian and unstructured mesh types, as well as the CHT and CAA capabilities is discussed in some detail. Several NASA mission related applications are also presented to demonstrate the capabilities for large-scale applications, such as pressure, thermal and acoustic analyses of the geometrically complex launch environment, steady and unsteady ascent aerodynamics, plume-induced flow separation analyses of heavy lift launch vehicles and aeroacoustic applications. In addition, two validation cases related to NASA aeronautics applications are presented: the 1st AIAA Sonic Boom Prediction Workshop test cases and a computational study of slat noise.