GaN HEMT has been expected to satisfy requirements being used in space as amplifying devices of future high-efficiency onboard SSPAs due to its excellent properties such as robustness in a harsh environment, applicability to high frequency and high power operation. However, in X-band, the most important frequency band for space communication at this moment, evaluation of GaN HEMT to prove the space usage has not been conducted yet because ensuring a steady supply of X-band GaN HEMT devices is still difficult due to current collapse phenomena. Therefore, in this research, evaluation of RF characteristics affected by operational conditions and space environmental testing of X-band HPA using COTS GaN HEMT was conducted to secure the space usage.

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Acoustic measurements of exhaust nozzles using a shock tube driven by compression air were conducted to validate the methodology and accuracy. The original method was proposed by Kirk( J. Propul. Power, Vol. 17, No. 4, 2001, pp. 928-935) to reduce the cost of acoustic tests of exhaust nozzles and improve the test efficiency. They showed a feasibility of the technique. However, we thought again the necessity to meet the tailoring condition of a shock tube at the nozzle temperature to simulate take-off condition. Validation tests up to temperature ratio of 1.7 using ASME standard nozzle were conducted and the uncertainty analysis was performed. It was found that the acoustic data agreed with the data obtained by a conventional facility within 1.3 dB for overall SPL even if the shock tube was operated under over-tailored conditions. The uncertainty analysis showed that the data was available with uncertainty of ±0.5-0.7 dB or less for 1/3 octave band SPL and a key component of the uncertainty was jet condition. Acoustic measurement of nozzles using a shock tube driven by air will provide good productivity under those uncertainties.

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HORYU-II is a 30 cm-cubic shaped nanosatellite weighing 7 kg developed by Kyushu Institute of Technology. Its main mission is demonstration of high voltage technology. HORYU-II went through extensive tests utilizing the facilities of Center for Nanosatellite Testing at Kyushu Institute of Technology. We reflect on its verification and testing processes of the project that started in April 2010 and ended in May 2012. We consider the effectiveness of each process by comparing the results obtained after the launch that took place on May 18, 2012. Especially, HORYU-II suffered serious anomaly for one month in June 2012 where it could not carry out any missions. We present the result of anomaly investigation.

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Airships with small horizontal cross-section and tall height are proposed. Such vertical airships have a remarkable advantage with respect to available locations for landing and mooring. Flight tests and wind tunnel tests of vertical airships were carried out using scale models. Drag coefficient of vertical airships is discussed.

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In the future air transportation system, airspace will be efficiently used and each aircraft can optimize its own performance. Due to limited capacity of the airspace like terminal area, however, some sort of adjustment for each aircraft is necessary to maintain separation among multiple aircraft. Fixed arrival time is a basic solution to the problem. This paper studies the effect of arrival time assignment on the performance by assuming that each aircraft generates its own flight plan by minimizing its fuel consumption. Dynamic programming trajectory optimization is used to calculate the optimal flight profile composed of altitude and velocity. The result shows that the arrival time adjustment is efficiently performed in the descent phase, if the required amount of time to be adjusted is not large.

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The primary aim of this work is to construct the high precision formation flight control law applicable to the Formation Flight All-Sky Telescope mission, FFAST. FFAST is the X-ray telescope mission consisting of two formation flying small satellites. The focusing distance is 20 m, which is difficult for one satellite to realize, however precisely controlled formation flight enables to construct the long focus X-ray telescope system. The relative distance between the two satellites is required to be maintained within 20 m ± 5 cm. To estimate the feasibility of the high precision formation flying control law under "real-world" dynamics, perturbed forces caused by the Earth's gravitational potential, the air drag, the solar radiation pressure and the disturbing forces by the other celestial bodies are considered in this paper.

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Two separation cameras and four fixed monitor cameras are mounted on solar sail demonstrator “IKAROS” in order to get panoramic view of the sail. Both cameras were designed to be wide field of view, and this cause huge lens distortion. In this paper, we describe the method to correct lens distortion and estimate the dynamics of separated cameras based on bundle adjustment, and also measure the displacement of sail tips using images taken by the two different kinds of cameras on orbit. For 3-dimensional shape estimation of the membrane, we use renormalization technique for removing statistical error bias, and find that the membrane is slightly bent to the direction of the sun.

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Flight trajectory optimization as well as trajectory based operations is considered as a key concept of future air traffic control system. Now, one of the significant subjects is to clarify the accuracy of numerical weather data such as wind speed or wind direction, which is used for calculation of flight trajectory optimization and trajectory prediction. In this study, the accuracy evaluation of numerical prediction GPV (Grid Point Value) data published from JMA (Japan Meteorological Agency) is assumed to be possible by comparing with flight data provided from an airline company. Accuracy of static air temperature and wind speed of GSM (Global Spectral Model) and MSM (Meso-Scale Model) weather data are evaluated and measured by RMSE (Root Mean Square Error). The analysis shows that temperature and wind RMSE of GSM and MSM initial time data are less than 2 degrees and 5 m/s respectively. It is also revealed that forecast data of GSM provides greater precision than MSM by referring to the obtained RMSE.

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The purpose of this paper is to verify the effectiveness of self-sensing piezoelectric actuation using an affordable micro-controller. In recent years, space structural systems have been required high precision and high functionality for advanced space missions. Vibration control is one of important issues to realize high mirror accuracy of antennas for a high-resolution observation and a high-capacity communication. Generally, active vibration control needs not only actuators and sensors, but also AD/DA converters and highly advanced arithmetic processing. However, it is difficult to mount complex and heavy devices on satellites. A compact and modulized unit for vibration control is necessary. Then, this study focused on an affordable micro-controller that is small, low power consumption and easily-available. And self-sensing actuation was chosen as the vibration control technique to reduce in size and weight of the control system. Numerical simulations and experiments to damp free decay vibration and harmonic vibration of a smart cantilever were demonstrated, and show that the presented approach is very useful for realizing the active vibration control unit.

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For future space transportation system development, efficient liquid propellant acquisition technologies under microgravity could be required to realize long-term missions in orbit. Microgravity environment is generally established through drop tower, parabolic flight by airplane or orbital/suborbital experiment. These methods are large-scale or not flexible so that compact and simple method is needed for the efficient development. To respond to such request, we propose a static experiment on the ground to realize the similar static free surface under microgravity. The ground experimental result was compared with the results of two types of two-phase flow simulation codes for the verification of the methodology and discuss the characteristics of these numerical codes. We also simulated the free surface under the actual flight condition by using the same simulation method and result showed the validity of the experimental method.

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An electric sail is a new propulsion system uses the solar wind dynamic pressure as a thrust force. We analyzed the probability of the orbital control not changing sail plane angle but switching an electron gun connected with tethers. First, locally optimal switching laws are derived from Lagrange variational equations analytically. By theoretical calculations and numerical simulations, these switching laws are effective for changing some orbital elements. Moreover, mission applicability is studied. Assuming minimum time transfer problem between circular and coplanar orbits, optimal control laws are studied with direct approach. We conclude that the switching orbital control method is effective for exploration of other planets.

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This paper presents experimental results of effects of the booster configuration on orbiter aerodynamic characteristics of TSTO type space plane in supersonic region. For booster configurations triangle, square and circle cross sections are selected and blunt and sharp nose shapes are selected. Orbiter is a wing body configuration. Results of optical flow visualizations and orbiter aerodynamic characteristics have been obtained at angle of attack of 0 degree by changing clearance length between the booster and the orbiter. Results of the optical flow visualization show that the strength of shock wave generated by the booster nose depends on the nose configuration and the strength of reflected shock wave by upper surface of the booster depends on the cross section of the booster. And results of 6 components aerodynamic force measurements of orbiter show that significant reduction of variations in lift and pitching moment of the orbiter caused by bow shock wave and reflected shock wave are observed in case of triangle cross section for booster. The orbiter aerodynamic characteristics show that the booster nose shape and fuselage cross-section are significant parameters in TSTO type space plane design for reduction of shock wave interference.

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Ideal goal of the future air traffic system is recognized that every aircraft can freely fly in the sky to optimize its own performance. Since the trajectory optimization depends on aircraft performance characteristics, the performance model is one of the key elements for practical applications. As for cruise phase, it is known that a periodic dynamic maneuver is the optimum when a simple model is used, but the maneuver is not actually used in real flight operations. This paper studies what parts of the model characteristics are influential on the optimality of the periodic dynamic maneuver in cruise flight. It reveals that engine performance model and atmospheric characteristics are two influential parameters, which justify the optimality of steady horizontal flight for cruise phase.

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The aircraft descent profile has many factors, such as selected airspeed, flight weight, wind, initial altitude, and outside temperature even if fixed idle thrust was assumed. This article tries to prove a rule of thumb that "Even if the wind changes at lower altitude during descent, the flight path will converge at a lower altitude". This may be useful information for flight operation, if it is correct. In addition idle thrust descents are a useful method for fuel economy operation. This paper tries to support this rule of thumb by numerical simulations of flight paths with different wind conditions.

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Precision agriculture has been being implemented in order environmentally friendly and efficiently to product and manage crops. The remote sensing by satellite and aircraft is employed in order to obtain the information regarding the growth of crops. Although the data from satellites can include wide-range image each time, it is insufficient due to the fixed orbital path of satellites. Therefore, fixed-point observations cannot be sufficiently performed. Moreover, the observations on fixed orbital path cannot be always carried out because of cloud. Although aircrafts are used for the interpolation of the insufficient data by satellites, manned aircrafts need high personnel expenses and maintenance costs. Therefore, unmanned aerial vehicle (UAV) is recently employed. The objective of the present study is the development of the system to generate the interpolated image data by normalized difference vegetation index (NDVI) map taken by small-type UAV (sUAV), which is low-priced and simple system to implement precision agriculture. The following three assignments have been concretely performed in the present study; 1) light-weight four-band multispectral camera carried in sUAV will be developed, 2) sUAV is managed and the image data will be taken, and 3) NDVI map will be generated from the image data by sUAV and interpolated image data will also be developed to contribute precision agriculture. Consequently, the lightest four-band multispectral camera in the world has been developed, and also sUAV has been able to be successfully managed and acquired image data could also generates NDVI maps.

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