The All Japan Student's Indoor Flying Robot Contest has been held every year since 2005. The Mayfly and its revised airplane were winning airplanes at the 3rd, 4th and 5th Contest. The most remarkable features of the Mayfly are its low aspect ratio wing (about 1) and its high dihedral angle (about 15deg). In this paper, the stability of the Mayfly was analyzed. The results revealed the followings. (1) The high stability of spiral and dutch roll modes are caused by the high dihedral angle. (2) Added mass of the wing affects the flight stability strongly because of the small body mass.
The present paper treats a semi-active vibration control based on a synchronized switch damping (SSD) technique. To enhance the performance of semi-active vibration control method, the piezoelectric energy harvesting techniques are adopted instead of constant voltage sources in SSD on voltage sources (SSDV). This harvesting technique exploits the property of piezoelectric vibration to electricity converters, and requires no external voltage source. An experimental verification of the present vibration suppression method named as a synchronized switch damping on piezoelectric energy harvesters (SSDP) for CFRP cantilevered beams is carried out. The experimental results show that the proposed vibration control method is effective for vibration suppression of composite structures as well as SSDV technique. It is also shown that there exist threshold values of generated voltage of the piezoelectric element and excitation frequency of the cantilevered beam in energy harvesting device for achieving stable control effect based on the present method.
The MHD heat shield under the condition of the super-orbital reentry flight is numerically analyzed with consideration of the radiative wall heat flux. The flow field around a capsule body is computed by the two-dimensional computational magnetohydrodynamics code developed by the authors. The radiative wall heat flux is calculated by the structured package for the radiation analysis ``SPRADIAN''. The main results show that the convective wall heat flux decreases by applying the magnetic field, whereas the radiative wall heat flux increases. The increase in radiative wall heat flux by applying the magnetic field is mainly attributed to the expansion of the shock layer and the rise of the plasma temperature. Under a strong magnetic field condition, the total wall heat flux, which is defined as the sum of convective and radiative wall heat fluxes, increases by applying the magnetic field due to the increase in the radiative wall heat flux.