The Advanced Solid Rocket (currently Epsilon Launch Vehicle) is under the development by JAXA (Japan Aerospace Exploration Agency). In this study, using our cutting-edge CFD technology, we carried out numerical analysis on the aerodynamic characteristics of the Advanced Solid Rocket at Mach 1.5. Six test cases were selected with different Reynolds numbers (wind-tunnel test and flight conditions), attack angles (0 and 5 degrees), and roll angles (0 and 60 degrees). Numerical results of the test conditions successfully reproduced the corresponding experimental data. The flight condition cases provided us with important data available at neither the experiment nor the actual flight, such as the normal force distribution, the rolling moment, Reynolds number effects, and detailed explanation of three-dimensional interactions between longitudinal vortices and the body. In particular, within the range of the wind-tunnel and flight conditions, Reynolds number turned out to have little effect on the flowfield and aerodynamic characteristics except for the rolling moment, whose difference of 19% being dominated by the leeward-positioned attitude control unit.

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Carbon fiber reinforced plastics (CFRP) are important materials in the aerospace field. An aircraft may suffer from foreign object damage (FOD) during operation. The most critical and frequent FOD events are bird strikes. To increase the usage of CFRP as a structural material in airplanes, it is necessary to be satisfied with the data on its impact resistance and to clarify the damage mechanism of CFRP in case of bird strike. In this study, a soft body sphere was used, as a model for a bird. The sphere struck three types of CFRP plates fixed at cantilevered, and the effects of the impact energy on the damage behavior of the plates were investigated. The relationship of strain and stress distribution and the damage process of CFRP were investigated through finite element analysis of the impact of the sphere.

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The suppression of low frequency oscillation for Hall thrusters is an essential challenge to be solved for practical applications, not only for the effects on the thruster operation, but also for the power consumption of the satellite. We present comparison of a low frequency oscillation at the 20 mN-class Hall thruster and the 250 mN-class Hall thruster within oscillation-mode-map. As a result, we defined a parameter of “the equivalent energy density” and succeeded in normalizing an oscillation mode map. The parameter “equivalent energy density” will provide optimal power control for Hall thruster system and lead a very important guideline for Hall thruster system design and operation. Using the electrical power control technology will make it easy to manage the power consumption in a Hall thruster system.

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In this study, we consider formation control of a group of plural unmanned aerial vehicles (UAVs). New algorithm and control rules that create a form and direction are proposed. UAVs make the cooperative formation to perform a task. It is most important that the formation fly over the target point with keeping a precise form. To take the advantages of both formations that have no-leader and leader, each UAVs has same ability and there is no leader at the initial point. To make a directional formation, the limitation of velocity is applied. The shape of formation is decided by changing values in the limitation. In addition, applying the concept of plant hormone to the formation flight, one of the UAVs becomes “leader” when the value of hormone exceeds the threshold value. The formations of 4 UAVs are simulated using simple rules of a directional formation. The stability of formation is also discussed. The results show that the new rules of a directional formation bring accomplishment of the objectives.

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Advanced design method for manufacturing large Fiber-Reinforced-Plastics structure, such as next generation satellites like quasi-zenith satellite, is developed. The design method enables high shape accuracy, strength prediction including thermal residual stresses without trial manufactures. The design, manufacturing, and tests of a satellite main structure (verification model) are reported. The verification model was used as main structure of Quasi-Zenith Satellite and successfully launched.

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The Epsilon Launch Vehicle, scheduled to be launched in 2013, is currently under the development by JAXA (Japan Aerospace Exploration Agency). In this study, aerodynamic characteristics of the Epsilon Launch Vehicle are investigated by conducting both wind tunnel tests and numerical analyses at Mach 0.7. In order to examine accuracy of the measured drag, we probed the cavity pressure in addition to the base pressure, in contrast to our earlier work for Mach 1.5. The measured data indicated that the cavity pressure can be substituted by the base pressure or the static pressure within 3% error, which accounts for 1% error in the fore drag estimation. Then, the fore drag, calculated based on the static pressure, was used for CFD validation. Our CFD results of attack angles of 0 and 5 degrees showed fair agreement with the wind tunnel results, including the surface flow pattern, the fore drag and the normal force. Finally, aerodynamic characteristics of Epsilon Launch Vehicle at Mach 0.7 are extracted from the CFD results: 1) contribution to total forces was clarified for each part (e.g., flanges and attitude control units), 2) the normal force profile at Mach 0.7 showed comparable peaks with the Mach 1.5 case, in spite of the smaller separation regions near protuberant parts, and 3) the Reynolds number effect turned out to be minor within the range of the wind-tunnel and flight conditions.

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This study is to propose a useful simple method in the case of initial design for analyzing beam — like anisotropy structures with rotation and/or extension. The anisotropic beam like structure with rotation and extension is modeled as following simplified structures; the mass-less beam which can only change length over time, and the rigid disk which can only change weight according to the length of beam. Using this model, the equation of motion is formulated to consider bending, extension and rotation. In this formulation, the follower force by inertia during extension is also considered. The stable region and the equation of motion are given which describe the dynamic behavior of beam's tip. To evaluate the validity of the numerical simulation results, the experimental apparatus is developed, which can change the length of anisotropic beams during rotation, and the displacement of beam's tip motion are measured. By the comparison of the displacement of beam's tip from rotation center, the analytical results become bigger than the experimental ones just after the extension. That displacement difference just after extension depends on the quantification of the eccentricity, which value changes correspond to the length. But considering about the internal damping, the simulation results get the qualitative tendency of the dynamic behavior of during extension and after extension.

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Air traffic control system is expected to evolve in order to respond to strong demand of air traffic growth by employing new technologies. Quantitative evaluation of safety is one of the most important issues for smooth transfer of new technologies or introduction of new rules for automation in air traffic systems. Probability evaluation of midair collision is a typical problem of the safety analysis. This paper discusses a classical problem of midair collision on an airway. Normal distribution is assumed for simplicity to evaluate the collision probability, and standard deviation of the distribution is taken as an uncertainty parameter to assess the effect of uncertainty. The approach can explain the so called “navigation paradox,” and it naturally introduces lateral-offset, or side-stepping, which is a long proposed scheme as a solution of the paradox in the airway guidance.

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Well-known orbital debris environmental models MASTER and ORDEM built by NASA and ESA respectively have big discrepancy in their debris flux models below the micro debris size scale. This paper addresses how to evaluate the confidence of MASTER and ORDEM by using debris detection rate acquired by in-situ debris observation on earth orbits. This paper suggests that ram direction is suited for the micro debris measurement to evaluate the confidence of MASTER and ORDEM. The proposed evaluation method expects one can judge the flux models of MASTER and ORDEM by 1-sigma degree of confidence in nearly every situation.

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The development of bus-structure for the further GEO satellite is described. The target of the further GEO satellite is to be the satellite with 8 kW solar generation, 3650 kg launch weight, and sufficiently global competitiveness on the next decade. The target weight of the bus-structure is lower than 215 kg (lower than 5.9 % of launch weight). The design and mechanical tests of the bus structure have been successfully completed.

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It is essentially important for on-orbit computers to perform high-level tolerance for anomalies and high calculation performance. Redundant structure using low cost processors is an effective strategy to achieve high reliability in low cost, but it enlarge system size and weight, and is less efficient. It is also difficult to achieve high calculation performance . In order to make a system redundant efficiently, it divided into the fatal portion and the portion whose performance is more important than reliability. The system was divided by class, the portion which needs reliability was made redundant, and the portion which needs performance was made simple composition. As a result, high reliability and high efficiency are realizable in low cost and small size. In this paper, the status of development for the actual proof of UNITEC-1 is introduced about OBC which realizes high reliability and high efficiency in low cost and small size.

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This paper describes the gravity effect on heat transport characteristics in a miniature loop heat pipe with multiple evaporators and multiple condensers. Tests were conducted in three different orientations: horizontal, 45 deg tilt, and vertical. The gravity affected the loop's operating temperature, the maximum heat transport capability, and the thermal conductance. In the case that temperatures of compensation chambers (CCs) were actively controlled, the required control heater power was also dependent on the test configuration. In the vertical configuration, the secondary wick was not able to pump the liquid from the CC to the evaporator against the gravity. Thus, the loop could operate stably or display some peculiar behaviors depending on the initial liquid distribution between the evaporator and the CC. Because such an initial condition was not known prior to the test, the subsequent loop performance was unpredictable.

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Estimating aircraft weight appropriately during the aircraft conceptual design phase is very important to fulfill the given design requirements. For this purpose, many weight estimation methods have been proposed. Since the detailed weight data of the existing aircraft have rarely been publicized, it is not easy to conclude which estimation method is recommended for designing the specific type of aircraft. In this paper, the civil transport weight estimation is discussed by comparing several weight estimation methods.

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We conducted multi-cycle combustion experiments of a coaxial-rotary-valve pulse detonation engine (PDE) system. This PDE system showed a stable operation at the valve rotating frequencies of 5.0, 10, 15, 20, and 33 Hz. We successfully measured propellant mass flow rates, thrusts, and specific impulses in the 2-sec operation duration. The maximum thrust was 32 N at the operation frequency of 33 Hz and at the supply pressure of 0.98 MPa. The maximum specific impulse was 250 sec at the operation frequency of 33 Hz and at the supply pressure of 0.69 MPa. The partial fill ratio was varied from 0.07 to 1.14. The partial fill effect was almost identical to the previous model calculations.

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