Economical power generation is expected from a jet stream since it has about 30 times higher energy density than other renewable energy resources. Moreover, Japan is most blessed with the jet stream energy in the world. Summary of our power generation concept and high-altitude flying capability by a large kite have already been described in Part 1 and Part 2. In this paper: Part 3, conceptual design of our entire power generation system and its economic aspects are described.
Direct numerical simulations are tried using finite difference methods to investigate the starting processes of the ram accelerator in Hiroshima University, the ram acceleration tube of which has a rectangular bore for easy observation. A projectile and an igniter fly at speed below C-J velocity from an evacuated chamber into a ram acceleration tube, where hydrogen-oxygen-nitrogen gas mixtures are filled as combustible gases. When the acceleration tube is filled by carbon dioxide as a non-reactive gas for the first test, the results of the numerical solutions give a good agreement with the experimental results. When combustible gas mixtures are filled in the acceleration tube, we could not get a solution without detonation or quenching. This kind of difficulty to start is also found in the experiments. The numerical results show how the igniter works in the starting process, those help our experiments.
This paper considers the minimum approach distance for landing of STOL aircraft, which is solved by a numerical computation method. Equations of motion use the dynamic model in which aerodynamic coefficients are stated as function of the angle of attack and thrust. Numerical results explain that the optimal minimum approach distance of the landing trajectory has two phases, the dive phase and pull-up phase. The control history of thrust has Bang-Bang type of control by using the minimum value in the dive phase and the maximum value in the pull-up phase. The angle of attack uses the minimum value in the dive phase, but it does not always use the maximum value in the pull-up phase in the case of different optimizing value.
Quasi-three dimensional finite element method (Q3-DFEM) has been widely recognized as an effective method in analyzing symmetric laminates loaded in the longitudinal direction. However, when laminates are not symmetric or when bending moment is applied, Q3 DFEM is not sufficient to analyze composite laminates. A generalized Q3 DFEM (GQ3 DFEM) accounting for bending and twisting of unsymmetric laminates has been developed. In this paper, GQ3 DFEM based on the Kirchhoff hypothesis for laminates is formulated based on deformations separated into two parts, which are the global displacements corresponding to CLT, and the local displacements representing local states. As the local displacements can be separated from the global displacements based on CLT, the effect of local geometrical irregularities is directly evaluated. GQ3 DFEM is used to determine displacements, stresses and energy release rates. Finally it is shown that GQ3 DFEM based on the Kirchhoff hypothesis is useful for predicting the behavior of composite laminates.
A method of estimating the rotational vector of a heavenly body using its monocular images is proposed. It deals with the case that the shape of the body is unknown and the motion contains translation as well as rotation. The paper focuses on the equation of observation relating optical flow and variables to estimate. Expressing the equation using the vector seen from a specific moving coordinate system, the number of unknown variables in the equation decreases. The rotational vector of the body is estimated by iteratively minimizing the loss function which is based on the equation of observation mentioned above.
This paper introduces the flutter phenomenon occurring in the automatic landing flight experiment for a Japanese unmanned space shuttle of HOPE-X. The experimental vehicle called ALFLEX which was a dynamically scaled model of HOPE-X was towed by one cable before its release. An oscillation was observed on the cable with release device during flights of towing configuration in the preliminary tests. The analysis revealed that the oscillation was caused by the coupling between unsteady aerodynamic forces of the release device and restoring forces of the cable. The flutter could be eliminated by mass balancing before the automatic landing flight.