The aerodynamic characteristics of a vertical landing rocket are affected by its engine plume in the landing phase. The influences of interaction of the engine plume with the freestream around the vehicle on the aerodynamic characteristics are studied experimentally aiming to realize safe landing of the vertical landing rocket. The aerodynamic forces and surface pressure distributions are measured using a scaled model of a reusable rocket vehicle in low-speed wind tunnels. The flow field around the vehicle model is visualized using the particle image velocimetry (PIV) method. Results show that the aerodynamic characteristics, such as the drag force and pitching moment, are strongly affected by the change in the base pressure distributions and reattachment of a separation flow around the vehicle.

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The atomic oxygen (AO) in low Earth orbit erodes spacecraft materials. Since the organic materials are significantly damaged by AO, we must evaluate the erosion effects during satellite missions before launch. The first step in evaluating the erosion effect due to AO is to determine the distribution of AO fluence and/or flux on the entire satellite surface during the satellite mission. The AO fluence on the satellite surface is different for different parts of the satellite surface because the ram surface receives AO changes according to the satellite attitude in orbit. Therefore, AO fluence must be estimated by considering the satellite attitude, shape, ram direction and AO density in orbit. However, there are no studies in which the AO fluence distribution is estimated for the entire satellite surface. In addition, there is no tool to analyze AO fluence distribution on the satellite surface. Thus, in this study, we construct an AO fluence distribution analysis tool and estimate the AO fluence distribution on the entire satellite surface.

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An advanced design method has been developed for manufacturing large fiber-reinforced-plastic (FRP) structures to be used in next-generation satellites such as the quasi-zenith satellite (QZS). The design method enables highly accurate shape and strength predictions, including of the thermal residual stresses, without trial manufacture. The design, manufacture and tests of the satellite’s main structure (verification model) are also reported. The verification model is used to make the main structure of the successfully launched QZS.

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The major aim of this paper is a simple approximate closed-form solution, which can be easily calculated using spreadsheet software, for the buckling of thin and moderately thick anisotropic cylinders under axial loads that includes the effect of layup anisotropy, transverse shear deformation and cylinder length. The Jaumann-strain-based solution satisfying both the equilibrium equations and the boundary conditions is derived and the differences between it and the Green-Lagrange-strain-based solution are shown to be very small. Then, the Jaumann-strain-based solution is simplified by neglecting the boundary conditions, and the simplified solution is shown to be sufficiently accurate.

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In this paper, the attitude dynamics of IKAROS, which is spinning solar sail, are presented. The first mode model of out-of-plane sail deformation (FMM) and multi-particle model (MPM) are introduced to analyze the oscillatory motion of the spinning solar sail. Three oscillation modes are derived from the FMM. They are caused by the nutation motion of the main body, as well as the nutation motion and the out-of-plane oscillation of the sail. The precise attitude motion after sail deployment and reorientation using thrusters is calculated using the MPM considering thruster plume. The IKAROS flight data of the nutation angular velocities of the main body after sail deployment or reorientation using thrusters are nearly equal to the analytical data found using the FMM and MPM.

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Many projects have made efforts to realize commercial supersonic transports (SSTs). These trials have revealed many barriers to the successful completion of various necessary project goals related to supersonic cruise efficiency, sonic boom annoyance, economic viability and also the development of solutions for avoiding environmental problems. The shift of aircraft fuel from kerosene to liquid hydrogen will come in the near future. The purpose of this study is to discuss the feasibility of a hydrogen-fueled, low-boom SST designed to carry 50 passengers for a range of 3,500 nm at a Mach 1.6 cruise speed using a method which considers the effects of hydrogen and incorporates the sonic boom minimization theory. A multi-point optimization using a genetic algorithm is conducted. The objective functions are to maximize range, minimize takeoff weight, W_TO, and to minimize the difference of equivalent areas, ΔA_E, which is a metric about sonic booms. The design variables were the fuselage fineness ratio, cruise lift coefficient and wing area, which are fundamental for aircraft performance. The results show that there are trade-off relationships among them. By analyzing the higher-ranked populations that have lower ΔA_E, the promising range of a wing area, a cruise CL, and an altitude for the reduction of ΔA_E are revealed.

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An aircraft may suffer from foreign object damage (FOD) during flight operations, and a bird strike is a potentially serious and damaging FOD event. For simulated bird strike experiments, gelatin has been traditionally used as the projectile material. However, it has not been sufficiently determined how the material properties of the projectile affect the simulated bird strike results, especially for deformable targets. In this work, using gelatin as the conventional simulated bird material, silicone resin is used to investigate the effects of the projectile material properties. Two types of impact tests are conducted. One uses a solid target with a flat face, and the pressure change due to the impact is investigated. The other uses a cantilever target made from aluminum alloy or carbon fiber/epoxy composite laminate to investigate the plastic deformation or damage, respectively. From these experiments, the effects of the projectile material type and properties are evaluated.

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