Super-Sonic Transportation is provided with a thin and low-aspect-ratio wing on which shock waves do not appear till high Mach number and hardly causes the flow separation. If the shock-induced separation dose not appear, the flap might oscillate divergently in a single degree of freedom. This phenomenon is called as “Region B Aileron Buzz.” It is a basic and important research to investigate the shock wave movement caused by the flap oscillation. The present study numerically simulates the flow around a two-dimensional thin airfoil with an oscillating flap. The fluctuations of the flap hinge moment (FHM) are strongly influenced by not only the mean shock wave position but also the region of the shock wave movement. The imaginary component of FHM shows the maximum value when the shock wave oscillates only on the flap. The energy produced by FHM also shows the maximum under this flow structure.
Transportation missions are absolutely necessary for practical use of the ISS. The launch window of the present rockets or shuttles mission is very narrow because it is necessary to ascend on the same orbital plane of the ISS. In comparison to those spacecrafts, a spaceplane can change its orbital plane by turning in the atmosphere, and has potential of having wide take-off window. On the other hand, the minimum fuel consumption must be considered, since the payload of a spaceplane is severely limited. Therefore, this paper considers the optimal control problem of spaceplane's ascent trajectory, and evaluates its take-off window. The Block Diagonal Hessian method which transforms optimal control problem into nonlinear programming problem is applied and the superiority of a spaceplane is demonstrated in the point of launch window.
As basic researches to clarify aero-mechanical behaviors of a tilt rotor, the blade flapping motions during low speed transition state are analyzed using the proposed inflow model for a rotor being subjected to uniform flow with arbitrary attitude angle from 0° (rotor mode) to 90° (propeller mode). The inflow model is formulated by extending acceleration potential theory for a circular wing so aerodynamic load and corresponding induced velocity distributions as to be consistent with the flapping motions obtained by dynamic running test with the model rotor. Comparisons between calculated and measured blade flapping motions for the rotor both at fixed attitude and tilting conditions are made, thus ascertained usefulness and reasonability of proposed inflow model.
Control to improve control characteristics of aicraft, CA (Control Augmentation), is used to realize the desirable motion of aircraft corresponding to pilot's control action. C* criterion is an important factor for the pilot's preferred longitudinal motion. The time history of C* corresponding to step input is specified to be within the upper and lower envelope, and that near the center of the envelope is best for the pilot's easy control. In this research, the control laws for control augmentation of small supersonic aircraft were designed using fuzzy logic control to obtain the C* response near the center of the envelope. The evaluation of the designed control laws showed good performance in all flight conditions. Here, the control laws were varied by only one scaling factor for dynamic pressure. Therefore, the gain schedules by Mach number and angle of attack, which are necessary for supersonic aircraft in which the control laws were designed by model following optimal control, are not necessary. This proves that fuzzy logic control is an effective and flexible method when applied to control laws for control augmentation of aircraft.
Assuming that an optical telescope observes the line-of-sight direction of a near-synchronous satellite, the error in the orbit determination and prediction is theoretically assessed and formulated. The formulations clarify how the orbit determination accuracy increases as the optical tracking period elongates from one night to two nights or more. The theoretical formulations agree with optical tracking experiments.