Attitude control methods of a solar sail which maximize the effectiveness of ΔVEGA (ΔV Earth Gravity Assist) are proposed. An orbit of a solar sail is controlled by changing its attitude, and there are two types of method to control an orbit of a spinning solar sail. One is to control its attitude directly, and the other is to control its attitude indirectly using an attitude drift motion due to the solar radiation pressure by controlling its spin rate. These methods are applied to an orbit of ΔVEGA, and their efficiency is quantitatively evaluated by solving optimal control problems to maximize the relative velocity with respect to the Earth.

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An attitude sensing system using thermopile sensors and inertial sensors was proposed. The output model of the thermopile sensor was constructed from the calibration experiment and the theoretical calculations. The estimation algorithm of the attitude angles was developed from the sensor output models using extended Kalman filter. Because thermopile sensor output correlates with attitude to the ground directly, the error of inertial sensors can be compensated. Additionally, the proposed system consists of commercial low-cost product. Numerical simulations and experiment were carried out and the performance was validated. Experimental result shows that the proposed system has precision of approximately 1.2°.

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Modified PARSEC (PARametric SECtion Method) is used as a parameterization method to describe airfoil shapes by few number of parameters, which is suitable for airfoil design optimization. To calculate these parameters, GA (Genetic Algorithm) is usually used. However, it has been observed that for some airfoils, Modified PARSEC method generates irregular shapes when GA is used. To overcome this issue, a new method using Pseudo-Inverse Matrix is developed. The proposed method is applied to various airfoils including the airfoil sections of the CRM (Common Research Model) wing, and a two-dimensional CFD code is used to carry out the aerodynamic analysis. Subsequently, the three-dimensional CRM wing is reproduced using the proposed method and its aerodynamic characteristics are analyzed with Euler equations. The results show that reproduced geometry is almost identical to that of the original CAD data in terms of aerodynamic characteristics, which shows the applicability and usefulness of the method.

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In the process of aircraft conceptual design, we determine the best aircraft configuration so that performance requirements can be satisfied. Aircraft secondary power systems, such as an environmental control system (ECS) and a hydraulic system, are indispensable for aircraft operation. However, the traditional aircraft conceptual design method has not considered the effect of these systems except for the weight estimation. Therefore, to think about the feasibility of the best designing point more in detail, conceptual design method considering aircraft secondary power systems is proposed in this paper and influences of secondary power upon the conceptual design results are examined. Although the proposed secondary power system model is a conceptual one, the results indicated that the aircraft secondary power systems, especially ECS, has some impact on specific fuel consumption which affects the design results.

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The feasibility in optimal control applications is increasing in recent years with rapid improvement of computational capability. User-friendly practical tools are highly required to meet complex design requirements in the field of aerospace engineering and dynamic programming is regarded as a powerful tool that satisfies these necessities. On the contrary, dynamic programming possesses a drawback so called ‘menace of the expanding grid’ or dimensional difference problem in applications where the number of control variables is fewer than that of state variables. This paper proposes a unique method to approach this issue and reviews its validity and feasibility by discussing a classical problem of Linear Quadratic Regulator (LQR) and an optimal gliding flight of an airplane that the analytically given exact solutions are checked for clarity.

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The present study proposes a new method to visualize the characteristics of periodically oscillating two-dimensional flow around a wing section by evaluating the local time delay using correlation analysis of the pressure gradient along the surface. The local time delay for a pair of arbitrary two points on the surface is visualized on the two-dimensional map (the correlation map) with both the horizontal and vertical axes describing the coordinate along the surface. To demonstrate the validity and the usefulness of the present method, the time-series data of the unsteady flow field are obtained from the numerical simulation around a NACA0012 wing section at Reynolds number 104. The correlation map clearly divides the flow field near the body into the region with almost stable flow, that with small amplitude velocity fluctuation and that with significantly oscillating flow. The advection velocity of the vortices shedded from the separation bubble is successfully estimated from the pattern of the correlation map. Furthermore, the spatial and temporal resolution necessary for the present method is determined. Consequently, the present method is useful for extraction of the characteristics of the periodically oscillating flow around a body, when the time-series data of the surface pressure distribution are available.

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STARS-II was launched on 28 February 2014, as one of piggy-back satellites by the H-IIA rocket. It had been developed in Kagawa University. STARS-II consists of Mother Satellite (MS) and Daughter Satellite (DS) connected by Electro Dynamic Tether (EDT). MS deploys EDT having DS at its end. DS is a tethered space robot, and it has one arm whose end is attached to the EDT. Main missions are follows: (1) Electro Dynamic Tether (EDT) deployment by gravity gradient, (2) gathering electrical current by EDT, (3) Attitude control by arm link motion under tether tension by gravity gradient, (4) Tether deployment and retrieval by tether tension control. Unfortunately, STARS-II mission could not achieved perfectly. However, the STARS-II condition can be inferred by telemetries through CW beacons and the change of orbit. This paper describes the planned missions and reports the operation results.

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In this paper, direction control of balloon gondola with only untwisting motor is proposed. Typically a reaction wheel and another actuator for unloading the reaction wheel are in use to control the attitude (or direction) of the gondola. Although this method can get high accuracy control performance, two actuators spend many resources of the gondola. The proposed method uses only untwisting motor installed above the gondola to rotate. This method can not realize such high accuracy control performance but realize direction control with the most simple configuration. The proposed method is applied to prototype GAPS (General Anti-Particle Spectrometer) balloon experiment in 2012. This paper shows control design for this experiment and the results of the proposed method.

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The airframe/propulsion integration for supersonic airliners was studied considering three engine layouts (i.e., under-wing, over-wing, and side-body engines). In this study, the engine position was optimized for each layout from viewpoints of low-drag, low-boom, and high-range performances. This study revealed that the interference between nacelle shock wave and wing is important to achieve low-drag and low-boom, and that side-body engines realize the best compromise between them by setting engine so that the nacelle shock wave acts on the rear part of the wing. The engine position affects the inlet aerodynamic performance, which in turn affects the range performance. However, the side-body engine remains optimum, even when the range performance is taken into account.

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A futuristic air transportation system should cope with high economic efficiency while ensuring safety of its users and customers. Hence, conflict resolution between airborne aircraft is necessary to achieve fuel optimized flight trajectories. In this study, as an approach for conflict resolution, we calculate the separation between aircraft and evaluate a degree of conflict by acquiring Secondary Surveillance Radar Data measured for 24 hours in the Kanto region. Moreover, we devise an algorithm for the purpose of revealing how air traffic controllers avoid aircraft interferences. In this method, we estimate control procedures by air traffic controllers and review results as the preliminary stage towards the development of a conflict-free trajectory optimization algorithm.

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A pressure estimation system which uses a new model of a Poisson equation has been examined. The primary objective of the system is to let PIV measurement more advantageous for a wake survey in aerodynamic design of aircraft. In the wake plane velocity, pressure and etc. are no longer two dimensional, then common methods for PIV pressure calculation do not work. That is why the new model called two and a half dimensional (2.5D) one has been developed. In this article, the system is examined for transonic flows in the view point of its ability for practical application. All the examinations are done by computation, where, instead of PIV measurement velocity data, those of CFD simulation results are used. Firstly, the accuracy of estimated pressure distributions is verified for the flows of Mach 0.82. Secondly the isentropic relation of pressure and velocity is introduced as a convenient technique to impose boundary conditions for the Poisson equation. Then, the system is further examined if it is available to the variety of configuration of PIV measurement region. The results show that it has good ability for the variety of region sizes, shapes and the number of divided sub-regions.

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A full-field surface shape measurement method synthesizing a surface measurement method and a point measurement method is proposed in order to capture a surface shape of a large space structure with high accuracy and spatial resolution. The proposed method reconstructs the full-field surface shape of the large space structures by connecting the partial surface shape data measured with the surface measurement. The connection is performed by the coordinate transformation of the partial surface shape data onto the reference frame. The coordinate transformation matrix is determined by the point measurement as calibration. The equation to derive the coordinate transformation matrix is formulated, and an actual surface shape measurement system synthesizing the photogrammetric measurement system using the grating projection method and the laser tracker measurement system is constructed based on the formula. By conducting a surface shape measurement for the spherical mirror model, it is shown that the constructed measurement system can measure the surface shape of the spherical mirror model with 0.05×10⁻³ mRMS accuracy and can connect the partial surface shape data with the same accuracy of the grating projection method, while confirming the feasibility of the proposed method.

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These days, the continuous descent operation (CDO) is one of the hot topics in the air traffic management (ATM). However, because of the congestion in the terminal area, some aircraft with the CDO are interrupted by climbing aircraft. To resolve this problem, the optimal conflict-free trajectory for the climbing aircraft is studied. To calculate the trajectory suitable for the ATM, the unique coordinate system is introduced. This coordinate system is called space-time coordinate system (STCS), and the vertical axis of the STCS is time. By the STCS, the time is able to be treated along with the position, and the temporal conflict resolution is able to be formulated along with the spatial conflict resolution. In this paper, the conflict-free trajectories with the spatial and the temporal conflict resolutions are calculated. These trajectories are compared in terms of the fuel consumption.

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Precise position keeping of a geostationary satellite using an electric propulsion system is investigated in this paper. Analytical mean orbital elements of the satellite which represent a long-term motion of the satellite by perturbation forces such as the gravitational effects of the earth’s oblateness, the sun, and the moon, and the solar pressure force are introduced. Then, a control law of the position keeping by using the analytical mean orbital elements is derived where four electrical thrusters are assumed and the control forces are properly distributed into the thrusters. The effectiveness of the proposed control law is demonstrated by numerical simulations.

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The direct simulation Monte Carlo (DSMC) method has been developed for a numerical method in a rarefied gas flow, and now has been expanding its feasibility to continuum flow, that is, applicable to whole flow region of aerospace. Although Meiburg has pointed out that it is difficult for the DSMC method to deal with flows including vortices since a collision pair of molecules is selected in a cell in disregard of their locations, the DSMC method using the new collision scheme (U-system) has been verified to be effective for flows with periodic vortex shedding at the 24th international symposium on rarefied gas dynamics by Usami and Mizuguchi (Physics of Fluids, Vol. 29, No. 10 (1986), pp. 3107-3113, AIP Conference Proceedings, Vol. 762 (2005), pp. 686-691). One problem to resolve associated with U-system was such that the momentum and the energy accompanied with a collision pair were not conserved simultaneously during U-system collision process. Sun et al. have found that the correction scheme evolved by Pareschi and Trazzi for momentum and energy is useful for the conservation process in the U-system (AIP Conference Proceedings, Vol. 1084 (2009), pp. 311-316, Int. J. Numerical Methods in Fluids, Vol. 48, No. 9 (2005), pp. 947-983). The purpose of this study is to confirm the efficacy of the U-system with Pareschi's correction by use of an analysis of one-dimensional normal shock wave that includes extreme non-equilibrium over the whole region of the wave. Because of one-dimensional problem, stringent comparisons of the course cell results obtained by the U-system and the fine cell results by the conventional collision scheme can be carried out easily.

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Aircraft motion under the down-burst is analyzed using the fluid-flight coupled simulation. As a result, the results from the coupled simulation and the results from the conventional method were in good agreement with each other. However, it is found in the coupled simulations that simulated trajectory of the aircraft under the influence of the down-burst is sensitive to the selection of the turbulent model for the fluid dynamics simulation.

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A piston compression process of a gun tunnel was calculated by the coupling analysis between the one-dimensional CFD and the equation of motion. In this study, the relationship between the piston property (corresponding to reciprocal of the non-dimensional piston mass), ε and the maximum piston position, x_max was investigated parametrically, at the initial pressure ratio of 10. In the case that ε is smaller than 0.06, x_max corresponds to the isentropic theory, i.e., heavy piston operation. On the other hand, in case of ε larger than 3, x_max corresponds to the multi reflection theory, i.e., light mass piston operation.

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The Digital Paper Airplane has been constructed, in which aerodynamics and flight dynamics are coupled and are developed. It is one of fundamental approaches to complete the Digital Flight. To compute flights for six degrees of freedom, Moving Computational Domain method was adopted. The method can remove a restriction of region size, by moving computational domain itself according to motion of the airplane. Then, the combination with LES also investigated. After comparing with experimentation of a downward flight, a validity of the method was shown. Applying to various flights, the features of the method was shown in this paper.

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The surveillance control of multiple aircrafts with sensor visiting multiple stationary targets to obtain the state of the system is discussed in this paper. The control law consists of a target selection law and a motion control. The target selection law is based on an evaluation function using the Fisher information of targets. The Fisher information in each aircraft is updated by exchanging state of the system with restricted communication range. Then we introduced “Recognition area” of aircrafts in which an aircraft recognizes targets as candidates to visit. This method gives aircrafts updating state of targets which locates far beyond the sensor range. Dynamics of aircrafts is optimally controlled by the Dubins car model with a changing velocity. The simulation gave two results: (1) the aircraft has shown equal visit to all the targets for different arrangements of targets and (2) the cost for control of velocity has decreased compared to that of visiting targets in a designated order.

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The hypersonic air-breathing engine, which is currently under development by Japan Aerospace Exploration Agency (JAXA), uses liquid hydrogen as the fuel. In order to accurately control the fuel flow rate during the start-up, it is essential to measure the heat transfer and pressure drop of the two phase flow. These two characteristics depend on void fraction, flow velocity and flow regime; thus, measurement methods for these values are required to be established. In this study, the void fraction measurement method by the high-speed image analyses has been developed. Two images taken from top and side directions by high-speed cameras of 1000 fps are used for “two-direction semi-automatic analysis”. We also develop “One-direction full automatic analysis” which uses only the side view as a full-automatic and high sampling rate method with little accuracy deterioration. The preliminary verification test using vertical pipe and acrylic ball shows favorable results within 2.2€% error against the theoretical value. A cryogenic experiment using two-phase nitrogen flow was also conducted. Sampling rate of “One-direction full automatic analysis” can be up to 1000 Hz. The difference between the results of two methods was as minor as 5€% when the void fraction was below 30€%.

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Flight efficiency of passenger aircraft scheduled flights is analyzed by using surveillance radar data. Flight parameters which are necessary to evaluate the flight efficiency such as air speed and fuel flow are estimated from position data of the radar data by combining weather prediction data and aircraft performance models. Trajectory optimization is applied to the estimated flights in order to evaluate the flight efficiency by comparing with the minimized fuel and flight time. Arrival flights to Tokyo International Airport are analyzed to demonstrate the approach.

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We have developed a small size，lightweight 4 bands multi-spectral camera for micro-satellites, nano-satellites and cube-sats and soon. This spectral camera can select several wavelengths required by earth observation experiments, by exchanging the optimum bandpass filter.

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