Large Launch Vehicles Research Articles

Effect of Reynolds Number and Aeroelastic Scaling Upon Launch-Vehicle Ground-Wind Loads

NASA conducted a launch vehicle ground-wind-loads investigation at the NASA Langley Transonic Dynamics Tunnel to investigate wind-induced oscillations (WIOs) of a launch vehicle when exposed to ground winds before launch. Previous publications from this effort have documented the effects of an atmospheric-boundary-layer profile on WIO response and the correlation process between model-scale and full-scale wind characteristics and resulting structural loads. This paper will focus on the importance of aeroelastic scaling and the impact of Reynolds number on WIO response. As described in the literature and confirmed in the present investigation, aeroelastic effects can significantly increase the magnitude of measured loads. Additionally, vortex shedding is sensitive to nuances of the flow in the shear layer, which is governed by Reynolds number. Many wind-tunnel facilities are not capable of producing flight Reynolds numbers for the ground-wind-loads problem. At very low Reynolds numbers, laminar shear layers exhibit different behavior, resulting in different vortex frequencies, oscillating lift magnitudes, and motion sensitivities. This investigation demonstrated that low Reynolds number testing can yield substantially lower dynamic loads with less aeroelastic coupling than those acquired at flight-representative Reynolds numbers for a resonant WIO event. Additionally, a resonant response phenomenon present at flight Reynolds number was absent at low Reynolds number. Conversely, for nonresonant WIO response conditions, similar dynamic load coefficients were obtained for similar test velocities at either Reynolds number condition. These findings impact many large launch vehicles, including the NASA Space Launch System series of vehicles.

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.

Adaptive control design for active Pogo suppression of large strap-on liquid launch vehicles

In order to better solve the problem of Pogo stability considering parameter uncertainty and time-variation in the large launch vehicle, the model-reference adaptive control based on the dimensionality reduction model (MRAC-DRM) is proposed. Firstly, the state space Pogo model with an active controller is established for control system design by the improved Rubin method. Secondly, a greatly reduced dimensional model of the Pogo control system is derived from the eigenvalue transformation theory, which preserves the features of Pogo instability and is appropriate for control design. Then, the reference model and adaptive control law are designed by the model-reference adaptive control method based on the reduced dimensional model. Finally, two examples with different types of propulsion systems are used to demonstrate the effectiveness of the proposed MRAC-DRM. Simulation results demonstrate that the proposed method not only has excellent adaptability to the Pogo systems with parameter uncertainty and time-variation but also is insensitive to the initial value of feedback gain.

Structural Analysis of Airplane Wing Using Composite and Natural Fiber Materials: A Survey

Abstract: Natural fiber-reinforced polymer-based composites are increasingly used in modern society due to their numerous benefits for uses in mechanical engineering. Polymer-based composite materials are widely employed in civil construction, automotive, aerospace, and many other industries due to their many benefits. Natural fibers can be used to create new, highperformance polymer materials because they are affordable, environmentally friendly, renewable, and partially and fully biodegradable. Examples of these fibers include EGR Glass R Glass, Carbon fiber, and S Glass, as well as kenaf, pineapple, sugarcane, hemp, oil palm, flax, and leaf. The purpose of this study is to explore the use of natural fibers and composites in the production of airplane wings, including mechanical characteristics, applications, and potential as well as problems and future demand for natural composite materials for engineering uses. A good 50% of the airspace's components are natural composites. Because natural composites have the ability to lower aircraft weight, they are currently being used to construct helicopters, military fighter aircraft, small and large civil transport aircraft, cockpits, satellites, launch vehicles, and missiles. Rudder, spoilers, LG doors, keel beam, airbrakes, elevators, turbine engine fan blades, propellers, rear bulkhead, wing ribs, main wings, interior fixtures, etc. Composites made of natural fibers are attractive and promising. The use of natural fiber-based composite materials is growing daily due to their strength and integrity. The natural fiber is a renewable, environmentally beneficial, and biodegradable raw material. Both its mechanical and thermal insulation qualities are strong in natural fiber. However, the loading placed on the natural fiber and its youthful modulus determines its strength In addition to discussing the benefits of natural fibers over other materials, this paper provides a description of the several types of natural fiber, their physical and mechanical properties, and their advantages.

The Overall Optimization and Design of the Long March 5 Launch Vehicle

The overall key technical research of the Long March 5 launch vehicle is introduced, such as the optimization design of large low temperature launch vehicle aerodynamic shape, attitude control design of swing booster engine, and large strap-on launch vehicle force and thermal environment analysis method, etc. The overall optimization technology scheme is advanced. New design and simulation technology are adopted and verified through the large ground test. Long March 5 achieves the 14-ton carrying capacity of GTO, and the overall technology reaches the international advanced level of similar launch vehicles. To meet the needs of deep space exploration missions, the overall technical research level of Long March 5 has been optimized and improved.

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.

General Scheme and Key Technology of Long March 5 Launch Vehicle Booster

The Long March 5（LM-5） series launch vehicle is the new generation large launch vehicle of China, which undertakes China’s lunar exploration project, deep space exploration and other national key projects. LM-5 series launch vehicle booster is the largest booster in China. The booster provides 90% takeoff thrust for the LM-5 launch vehicle. In order to ensure the successful development of the booster, the overall scheme and a number of key technologies of the booster are put forward. The engineering and technical problems of these key technologies are overcome in the development process, which lays a solid foundation and accumulates rich experience for the success of the LM-5 launch vehicle and the large cryogenic launch vehicle. Up to now, LM-5 series launch vehicle boosters have successfully completed flight tests, promoting the development and application of follow-up boosters.

Preliminary trajectory design for NASA’s Solar Cruiser: A technology demonstration mission

This investigation outlines preliminary trajectory design for NASA’s sail-based Solar Cruiser spacecraft, selected on December 3, 2020, to be a secondary payload launched with the Interstellar Mapping and Acceleration Probe (IMAP) in 2025. Trajectory optimization is carried out to ensure that Solar Cruiser can successfully reach a halo orbit about a Sun–Earth sub-L1 Lagrange point in under one year using only solar sail propulsion. Trade studies are performed to identify optimal trajectories subject to restrictions on sail incidence angles and deployment times, and off nominal initial-conditions are examined to determine the feasibility of the baseline mission profile. Results, thus far, show that Solar Cruiser can be incorporated as a secondary payload on IMAP while satisfying tight operational restrictions. However, additional work must be done to mitigate risks from large launch vehicle injection errors.

Optimization of Cylindrical Stiffened Shells in Large Launch Vehicles Considering Manufacturing Tolerance

Optimization of Cylindrical Stiffened Shells in Large Launch Vehicles Considering Manufacturing Tolerance

Effect of preheat and post heat on mechanical properties of 6061 aluminium tungsten inert gas welded joints

Tungsten inert gas (TIG) welded joints of 6061 aluminium are often used in the fuel tanks of large launch vehicles, because of the massive loads these vehicles carry, dealing with weld reinforcement on TIG joints represents an important issue in their preheat and post heat on mechanical properties. Experimental and calculation methods were used to investigate the effect of weld preheat and post heat on the mechanical properties of these joints. The purpose of this study was to determine the effect of preheat and post heat on mechanical properties of 6061 aluminium. The experimental result indicated that mechanical properties of Al 6061 of the welding changed. The hardness of weld metal increase in temperature 130°C = 68,72 BHN, in 160°C = 70,51 BHN, and in 190°C = 76,26 BHN. Tensile strength also increase in temperature 130°C = 158,57 N/mm2, in 160°C = 169,85 N/mm2, in 190°C = 174,50 N/mm2.

Self-Healing Control for Large Launch Vehicle Based on Extended State Observer and Adaptive Dynamic Programming

This paper investigates the self-healing control problem for the large launch vehicle (LLV) with system uncertainties, external disturbances, and actuator faults. First, the attitude dynamics of the LLV are presented, and the control-oriented model subject to undesired malfunctions is structured. Second, a novel extended state observer (ESO) is designed to estimate the disturbances and fault informations, and the nonlinear gain functions with two different linear ranges are introduced to improve the estimation accuracy and reduce the effect of peaking value problem. Then, an integral terminal sliding mode fault tolerant control scheme is proposed for the attitude faulty system, which would stabilize the closed-loop system even existing the disturbances and actuator failures. Besides, utilizing the adaptive dynamic programming (ADP) technique, a supplementary control with actor-critic structure is employed to further improve the system tracking performance and provide the additional compensation control input according to the bias between the desired value and actual one. Finally, the effectiveness of the proposed method is verified by the simulation results.

A Brazilian Space Launch System for the Small Satellite Market

At present, most small satellites are delivered as hosted payloads on large launch vehicles. Considering the current technological development, constellations of small satellites can provide a broad range of services operating at designated orbits. To achieve that, small satellite customers are seeking cost-effective launch services for dedicated missions. This paper deals with performance and cost assessments of a set of launch vehicle concepts based on a solid propellant rocket engine (S-50) under development by the Institute of Aeronautics and Space (Brazil) with support from the Brazilian Space Agency. Cost estimation analysis, based on the TRANSCOST model, was carried out taking into account the costs of launch system development, vehicle fabrication, direct and indirect operation cost. A cost-competitive expendable launch system was identified by using three S-50 solid rocket motors for the first stage, one S-50 engine for the second stage and a flight-proven cluster of pressure-fed liquid engines for the third stage. This launch system, operating from the Alcantara Launch Center, located at 2 ∘ 20’ S, would deliver satellites from the 500 kg class in typical polar missions with a specific transportation cost of about US$39,000 per kilogram of payload at a rate of 12 launches per year, in dedicated missions. At a low inclined orbit, vehicle payload capacity increased, decreasing the specific transportation cost to about 32,000 US$/kg. Cost analysis also showed that vehicle development effort would claim 781 work year, or less than 80 million dollars. Vehicle fabrication accounted for 174 work year representing less than 23 million dollars per unit. The launch system based on the best concept would, therefore, deploy small satellite constellations in cost-effective dedicated launches, 224 work year per flight, from the Alcantara Launch Center in Brazil.

The structural properties of paraffin wax based hybrid rocket fuels with aluminium particles

Paraffin wax has been identified as a feasible high regression rate hybrid fuel. For this reason, paraffin wax needs to undergo stringent performance measures to qualify it to meet the requirements necessary for a large scale launch vehicle. Energetic additives such as aluminium powders have been considered for their performance enhancing possibilities. This research focusses on measuring the structural performance of the fuels similar to what would be required for a solid propellant. Thus, structural properties of both pure and 40 W t% aluminised fuels are investigated. Additionally, both elastic and plastic structural properties of the fuel need to be determined for complete material characterisation. Strain rate and temperature dependence of the material structural properties are investigated in this work through compression and tension testing. Results indicate that the addition of aluminium increases the strength of the fuel. Also, a slight increase in temperature was seen to decrease the structural performance significantly. This means that the rate of thermal propagation within the fuel grain is an important consideration. Finally, strain rate dependence is evident in paraffin wax. Higher strain rates result in higher Ultimate Tensile Strength (UTS) failure points, at lower levels of strain.

An evaluation of the tip clearance effects on turbine efficiency for space propulsion applications considering liquid rocket engine using turbopumps

Large launch vehicles use their propulsion systems based on Liquid Rocket Engines (LRE) equipped with turbopumps. Turbopumps are complex rotary machines that supply high power, mass flow, and pressures in the engine system to reach the thrust requirements as determined in the rocket engine thermodynamic cycle. Strong engines need a secondary turbopump system called a booster. These boosters have pumps and turbines smaller than those of the main engine turbopumps, and their important function is to increase the fluid pressure at the inlet of the main turbopumps, mainly to avoid cavitation. In the present work, the influence of the tip clearance issues in an axial turbine installed to operate as oxidizer booster in the Space Shuttle Main Engine (SSME) were evaluated numerically. The results are compared with experimental data from National Aeronautics and Space Administration (NASA). The flow characteristics and the variation in the turbine efficiency for different jet velocities were determined for three different tip clearance values associated with the percentage of turbine blade height: 3.0%, 5.5%, and 8.0%. The turbine design, numerical issues, mesh generation and results are described and discussed. The methodology and numerical simulations used in the present work was consistent with the experimental data and can be extended for other correlated numerical simulations related to axial hydraulic turbines.

Feasibility analysis and application consideration of a rapid method to obtain subcooled cryogenic propellants

Subcooled cryogenic propellants that can significantly improve its own thermodynamic performances have attracted more and more attentions. To shorten subcooled time, a rapid method to obtain subcooled degree is proposed. To illustrate the thermodynamic essence of the method proposed as a whole process system, the thermodynamic analysis is carried out to explain the throttle cooling process. To quantitatively compare and explain the rapid feature, the thermodynamic model of cooling rate is developed to calculate the subcooled time and liquid consumption, and nonlinear equations are solved numerically. The effects of several key parameters are then analyzed. The results show that the method presented in this paper is feasible and effective. Compared with the conventional pumping decompression method, the subcooled time used the rapid method can drastically shorten, and even cut down on more than one half in some cases. The cooling way is changed from a conventional type of passive cooling to the novel type which combines active cooling with passive cooling. Subcooled time and liquid consumption are inversely proportional to the pumping speed, linearly positively correlated to the inlet pressure of the throttle valve, and exponentially positively correlated to the inlet temperature of the throttle valve. The proposed method can be applied at the launch site of large cryogenic launch vehicles in the future.

Effects of weld reinforcement on tensile behavior and mechanical properties of 2219-T87 aluminum alloy TIG welded joints

Tungsten inert gas (TIG) welded joints for 2219-T87 aluminum alloy are often used in the fuel tanks of large launch vehicles. Because of the massive loads these vehicles carry, dealing with weld reinforcement on TIG joints represents an important issue in their manufacturing and strength evaluation. Experimental and numerical simulation methods were used to investigate the effects of weld toe shape and weld toe position on the tensile behavior and mechanical properties of these joints. The simulation results indicated that the relative difference in elongation could be as large as 96.9% caused by the difference in weld toe shape. The joints with weld toes located in the weld metal or in the partially melted zone (PMZ) exhibited larger elongation than joints with weld toes located at the juncture of the weld metal and the PMZ.

Multidisciplinary Design Optimization of Waverider-Derived Crew Reentry Vehicles

The development of a multidisciplinary design optimization framework for crew reentry vehicles is presented. A waverider design methodology is used as the basis for the parametric design technique, with required modifications (e.g., leading edge blunting and integration of a cylindrical payload volume representing the crew compartment) used to allow the generation of practical reentry configurations. In addition to the shape design code, aerodynamics analysis, mass estimating, and trajectory/aeroheating analyses are linked using a multiobjective genetic algorithm optimization process to maximize vehicle downrange, additional payload mass capability, and lift-to-drag ratio. Pareto fronts were generated for three different launch vehicle capabilities ranging from 12,000 to 26,000 kg to orbit, and highlight the relationships between reentry vehicle payload mass, maximum lift-to-drag ratio, and downrange, as well as the fact that a medium-class or larger launch vehicle was required to meet the baseline mission payload mass requirement. Although the modifications necessary for the crew reentry vehicle mission resulted in a substantial reduction in lift-to-drag ratio relative to the idealized waveriders used in the design process, comparisons of several designs to the NASA HL-20 concept indicated that the waverider-derived design process can produce vehicles with an almost 30% improvement in maximum lift-to-drag ratio and the ability to carry additional payload mass on longer downrange trajectories.

Bolden "not a big fan" of private development of large launch vehicles

Bolden "not a big fan" of private development of large launch vehicles

Experimental and Theoretical Research Review of Hybrid Rocket Motor Techniques and Applications

A hybrid rocket motor combines components from both solid fuel and liquid fuel rocket motors. The fuel itself is a solid grain, (often paraffin or hydroxyl-terminated polybutadiene, known as HTPB) while the oxidizing agent is liquid (often hydrogen peroxide or liquid oxygen). These components are combined in the fuel chamber which doubles as the combustion chamber for the hybrid motor. This review looks at the advances in techniques that have taken place in the development of these motors since 1995. Methods of testing the thrust from rocket motors and of measuring the rocket plume spectroscopically for combustion reaction products have been developed. These assessments allow researchers to more completely understand the effects of additives and physical changes in design, in terms of regression rates and thrust developed. Hybrid rocket motors have been used or tested in many areas of rocketry, including tactical rockets and large launch vehicles. Several additives have shown significant improvements in regression rates and thrust, including Guanidinium azotetrazolate (GAT), and various Aluminum alloys. The most recent discoveries have come from research into nano-particle additives. The nano-particles have been shown to provide enhancements to many parameters of hybrid rocket function, and research into specific areas continues in the sub-field of nano-additives for fuel grains.

大尺寸测量场在运载火箭装配中的应用探析

随着运载火箭的发展，传统的测量手段已无法满足新一代大型运载火箭的装配需求了。利用数字化测量设备构建数字化测量场，精确定位运载火箭部件的空间位置姿态，是新一代大型运载火箭数字化装配的前提和基础。本文以新一代大型运载火箭大部段数字化装配为研究对象，讨论了几种数字化测量场的建立方法，并提供了测量场的工程实际实施方法，为航空航天及其他领域大部件数字化装配中大尺寸测量场的构建提供了参考。 With the development of the launch vehicle, the traditional measurement methods have been un-able to meet the needs of the assembly of the new generation of large launch vehicle. It is the premise and the foundation of large launch vehicle digital assembly to build digital measurement field for accurate measurement of launch vehicle’s position. Several methods of building digital measurement field are discussed by using large launch vehicle digital assembly as the research object. And then, practical engineering implementation methods of building digital measurement field are proposed. A reference is provided for the construction of large size measurement field to digitize assembling large components in Aeronautics and Astronautics, etc.