To validate the accuracy of the prediction using a rotorcraft analysis code rFlow3D, NREL Phase VI wind turbine is selected as a test case. The rFlow3D code is a multi-disciplinary analysis tool of flow-structure coupling, with trim analysis and noise prediction in additions. It is found that even with a relative coarse resolution blade grid, the Euler solver can predict the performance of the wind turbine quite satisfactorily when the wind turbine is operated in attached flow conditions. With a Navier-Stokes solver, the prediction accuracy is improved with the refinement of the blade grid and the highest power can be predicted satisfactorily. For this case, the elastic deformation of the blade is minimal and its effect on aerodynamics is negligible.

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This paper presents computational and experimental results on investigation of noise generation from the flap side-edge for high-lift device noise research models in JAXA. The main purpose of this paper is focused on investigation of the differences of the flow field between the models with and without the swept angle and taper-ratio of the wing by comparison of the computational results. In the case of wings with the swept angle and taper-ratio, the flap is deployed in a three-dimensional direction based on the wing planform. The changes of the behaviors of the vortices from the flap side-edge and resulting pressure fluctuations due to the flap deployment are shown.

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Effective solutions are required to meet the ever increasing demands in the aviation industry. Flight trajectory optimization is considered one of the core technologies to improve the operational performance of conventional air transportation systems. This paper provides an in-depth quantitative evaluation on potential benefits achieved by performing flight trajectory optimization with respect to a series of flight data obtained by secondary surveillance radar data. Dynamic programming is used as the optimization tool to achieve optimal flight trajectories by considering the tradeoff between fuel consumption and flight time. Meteorological data of the Japan Meteorological Agency and the base of aircraft data (BADA) model data of the European Organization for the Safety of Air Navigation are utilized to evaluate the operational performance of both flight data and optimal trajectories. Operational performance results of flight data show a significant variation in the tradeoff between fuel consumption and flight time according to descent speed selection and vectoring in the terminal airspace. Optimal trajectories achieve a considerable reduction of fuel consumption while complying with arrival time constraints by adjusting the top of descent setting and descent speed.

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In the past decade, both the economy and air traffic demand have been growing rapidly in the Philippines. As a result, Ninoy Aquino International Airport (NAIA) has had to cope with increasingly heavy traffic. To mitigate the effects of this traffic, an air traffic flow management (ATFM) system was introduced in the Philippines. In this paper, background on introducing the ATFM system is presented and its successful results in reducing the holding time of flights waiting to land at the NAIA are reported on.

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A novel aerosol observation and sampling system using a combination of a balloon and a UAV is developed in order to retrieve observation apparatuses and aerosol samples easily at low cost. Observation apparatuses are installed on a motor-glider UAV named Phoenix, and the apparatuses conduct observation and sampling during ascent of the Phoenix suspended by a free balloon. The Phoenix is automatically separated from the balloon at a target altitude, returns to the ground station by gliding automatically, and it is retrieved with the use of a parachute. Four sets of this system were prepared and brought to Syowa Station which is one of the Japanese Antarctic Stations by the first- and the fourth-named authors as summer team members of the 54th Japanese Antarctic Research Expedition (JARE54) in December 2012. Five observation flights were conducted in January 2013 using Phoenix-03. Aerosol observation and sampling in the five flights were successfully performed up to 10,000 m in altitude. Details of the Phoenix and flight results are described in this paper.

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In order to carry out a study to establish an operational concept of future trajectory-based operation (TBO), we need to consider an appropriate airspace safety index to describe hot spots using a relatively simple methodology without high computational burden. As the first step to identifying an appropriate method, we review several methods for safety indices and attempt to compare the advantages of each. This paper introduces some results of this survey and indicates its applicability to our TBO concept study and current topics. This paper first describes the TBO concept in contrast with the current airspace-based operation in air traffic management. Then, currently used safety indices and the concepts of the Propensity and Resilience used in the INTEGRA project are explained briefly. Finally, some considerations on the safety metrics are made and a new approach using a simple model is proposed.

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The fundamental tendency of deviation from a curved approach trajectory is investigated through a series of basic numerical simulations using a simplified aircraft model subject to wind disturbance. A set of numerical simulations has revealed that a large lateral deviation during a curved trajectory is inevitable, and that the lateral and vertical deviations correlate to each other. It is also revealed that the distribution of the flight trajectory deviation has an asymmetry; aircraft deviate inside of the average trajectory on the curved leg in the majority of simulation cases. Once the flight speed of an aircraft deviates from the reference value by some wind turbulence, it tends to be lower than the reference value because it is more difficult to accelerate than to decelerate because of the difference of the drag coefficient change amount between the faster and slower speed cases. This results in the distribution asymmetry of the trajectory deviation toward the inside of a curved leg, and quite large deviations toward the outside of the curved trajectory inevitably occur. From these results, it is considered that the protection space to assure the collision clearance should be defined so as to reflect the deviation tendency.

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In the past decade, small quadrotors have been widely used in various areas ranging from military to entertainment applications. Recently, quadrotors have become popular for demonstrating choreographed aerial maneuvers such as dancing and playing musical instruments with collaborative control of multiple vehicle systems. For collaborative control, several techniques are required. First, localization recognition is required to avoid collisions. Second, reliable communication is needed in order to receive information from multiple vehicles without disconnection. Finally, a ground control station is needed which can control multiple vehicles and play a mission scenario for the maneuvers. In order to accurately control multiple quadrotors indoors, a motion capture based system was developed. However, this system is expensive and sensitive to the surrounding environment. In this paper, we propose multiple AR.Drone control systems based on marker image with motion capture for an indoor environment in which GPS information cannot be received. We demonstrate aerial choreography with multiple quadrotors in accordance with a mission scenario.

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This paper focuses on autonomous path-following flight taking uncertainty and external disturbances into account. Integrated guidance and autopilot are developed using a second-order sliding mode approach that is one of the well-known approaches for mitigating so-called ‘chattering phenomena’. The input magnitude for such a higher-order sliding mode approach tends to be extremely large in the initial reaching phase. In this paper, a novel sliding surface is developed using Ackermann and Utkin's method for reaching the surface smoothly to attenuate such extremely large initial inputs along with uncertainty and disturbance compensation. The potential of the proposed methodology is demonstrated with some path-following application under wind turbulence. Performance comparison with a conventional higher-order sliding mode approach is also presented.

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In this paper, the fracture behavior of biomorphic C/SiC composites made from pine and radiata pine preforms was studied. The minimum repeating blocks of the biomorphic composites were defined as unit cells and modeled by finite elements. The periodic boundary conditions were applied at the unit cell boundary to simulate the macroscopic material behavior. The cohesive zone model approach was employed to predict the microscopic failure progression in the unit cells. The crack initiation and propagation behavior was investigated for the pine and radiata pine composite unit cells by simulating uniaxial tensile and compressive test conditions. The stress-strain curves were obtained and the fracture strengths were predicted. The effects of analysis model size and the variation of the microstructural arrangement on the predicted strengths and fracture shapes were examined.

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A combined stereoscopic particle image velocimetry (PIV) and acetone planar laser-induced fluorescence (PLIF) measurement system was developed to investigate turbulent mixing of a jet into a supersonic flow. The measurement was performed using a supersonic wind tunnel. Air was injected perpendicular into a Mach 2 freestream with a jet-to-freestream momentum ratio of 2.2. The system successfully measured the molar concentration of the jet using PLIF and the velocity in the flow-field using PIV simultaneously. These data yielded turbulent eddy diffusive flux that is a product of fluctuating velocity (v') and concentration (c'). The eddy flux of the streamwise component (c'u') was negative, and that of the heightwise component (c'v') was positive in the outer jet boundary region. Large-scale structures were periodically generated in the outer jet boundary and convected downstream. This large-scale motion induced negative c'u' and positive c'v' in the outer jet boundary. In the inner region of the jet, the air entrained by the counter-rotating vortices induced a positive v' and negative c' region, resulting in negative c'v'.

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The design of novel airfoils for airplanes invariably demands new knowledge of aerodynamics. PARametric SECtion (PARSEC) airfoil representation is one of the most promising methods for automated airfoil/wing design. However, because the airfoil parameterization was originally carried out for transonic flows, it may be difficult to extend its application to unknown flow conditions, including the low Reynolds number (Re) flow case. In this study, the representation of the PARSEC method is modified, especially around the leading-edge and applied to airfoil design using a multi-objective genetic algorithm, leading to an optimal design for potential development and use in a Martian airplane. Correspondingly, an airfoil that can obtain a sufficient lift and glide ratio under lower thrust conditions is considered. The objective functions aim towards maximizing the maximum lift-to-drag ratio generated and towards minimizing the drag at the maximum lift-to-drag ratio. In this way, information on the low Re airfoil could be extracted efficiently. The optimization results indicate that an airfoil with a sharper thickness at the leading-edge and a higher camber at the trailing- edge is more suitable for a Martian airplane.

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We propose a control system for a small fixed-wing unmanned aerial vehicle (UAV) transitioning from level flight to hovering without switching the controller gains and dynamical model. The proposed system is divided into translational and rotational control systems. Nonlinear equations of motion are linearized using a dynamic inversion method in the flight control system design. A robust rotational motion controller is employed because the attitude of the UAV is significantly affected by disturbances such as wind. During the rotational controller design, the quaternion system was employed in place of an Euler angle to express the attitude angle of the UAV. This method enables the successive elimination of nonlinear terms through nonlinear state feedback because it is not necessary to select a typical equilibrium point. The unknown parameters of the nonlinear equations and the velocity of the UAV are estimated by an observer that is based on the disturbance-accommodating control (DAC) method, and an extended Kalman filter, respectively. We have confirmed the effectiveness of the proposed flight control system through numerical simulations and experiments.

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In this paper, we propose a visual servoing algorithm for the automated docking of unmanned spacecraft. The proposed algorithm detects a set of custom visual markers using pyramid-based template matching for scale-invariance, and tracks the set of markers using a particle filter and the continuously adaptive mean-shift (CAMShift) algorithm for nonlinear movement. For fast execution, the proposed algorithm runs on general-purpose graphics processing units (GPGPUs) using compute unified device architecture (CUDA) and multi-platform shared memory parallel programming. The performance of the proposed algorithm is validated in flight tests using an indoor unmanned aerial vehicle (UAV) and a simulated docking adapters which showed satisfactory results.

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Guided-pin mechanisms for large space membranes are developed for the purpose of folding a tapered pattern precisely and folding a larger membrane using a smaller apparatus. The guided-pin, which applies displacement to the fold line, is introduced to the fold apparatus. To realize folding with the guided-pin, guided-pin mechanisms are designed, where a mixed spiral fold is employed as the target fold pattern. The guided-pin mechanisms are manufactured to perform fold experiments using the guided-pin. The experimental results show that a 5,000 mm-sized membrane can be completely and precisely folded by 1,400 mm-sized guided-pin mechanisms, and thus, the feasibility of folding using the guided-pin mechanisms is verified.

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This paper describes jet noise measurement recently conducted at the Japan Aerospace Exploration Agency (JAXA). Measurement techniques with regard to jet noise are of great importance for better understanding the noise generation mechanism and evaluating noise suppression characteristics of jet noise suppressors. As jet noise is influenced by the flow structure behind the nozzle, noise-related measurement should be done from various points of view. In attempting to satisfy these requirements, JAXA focused on three aspects of jet noise-related measurement: 1) the far-field sound properties, which the nozzle and subsequent jet provide; 2) the near-field sound sources formed primarily by the aerodynamic process; and 3) the flow profiles such as pressure and temperature distributions behind the nozzle or engine.

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A rainbow schlieren system with a spatial resolution of 20 μm is employed to determine the hue and density profiles in an axisymmetric domain with a field of view of 100 mm in diameter. The rainbow schlieren method is applied for the underexpanded sonic jet from a cylindrical nozzle with larger length-to-diameter ratios. Experiments have been performed in a range of nozzle operating pressure ratios from 2.0 to 5.0. As a result, rainbow schlieren images show jet boundaries, expansion waves, and oblique shock waves in the shock-cell structure by continuous color gradation. Density profiles at any cross-section of the jet flows can be obtained from the Abel inversion. The schlieren images and density contour plots for high nozzle pressure ratios show the archetypal characteristics of shock cell structures appearing repeatedly in the flowfield. Also, an analytical model to predict the flow properties at the exit plane of the cylindrical nozzle is proposed. It is shown that the analytical results are in good quantitative agreement with the experimental ones from the rainbow schlieren.

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This paper proposes an optimal guidance law for manned space transportation systems with constraints on terminal area. The motivation behind this study is to provide a general and efficient method for onboard path planning of reusable launch vehicles. This study presents onboard path planning by utilizing the Homotopy method. The method is remarkable in that the computational time can be predicted because the method does not use iterative calculations. This study reveals that the optimal variables are parameterized by cubic spline curves from the small number of points. The resulting nonlinear programming problem can be solved quickly, and with low computational burden. It can be said the trajectory is easy to track. The number of possible destinations will significantly increase by treating the scale of destination.

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