Low speed aerodynamic characteristics of non-axisymmetric slender bodies are experimentally investigated. The model shapes are elliptic cone, semi-circular cone and cone. The test range of attack angle is from 0° to 90°. Forces/moments are measured with 5 load cells and flow is visualized with oil flow technique and mini-tuft method. Their aerodynamic characteristics have strong non-linearities especially in side-force coefficient. Presence of the side force is related to that of the maximum normal force coefficient which can be seen from oil flow patterns.

View full abstract

The Marguerre equations which govern the moderately large deflection of isotropic plates with small initial curvature are extended to the dynamic case of orthotropic stiffened rectangular plates by employing a smeared out procedure. Simply supported boundary conditions with movable or immovable in-plane edge conditions and the initial deflection with double curvature are assumed. The modal equation for the nonlinear, large amplitude free vibration is established on the basis of a singlemode expression by using the Galerkin's method. Numerical results concerning the square plates with various combinations of stiffening parameters, initial deflections and in-plane edge conditions are obtained. The present results, when particularized for certain cases, agree well with those available in the literature.

View full abstract

Flight paths of a hypersonic-plane are formulated as optimal control problems. Minimum-time, minimum-fuel and maximum-range solutions are shown with varying fuel-to-weight and thrust-to-weight ratios. One of the findings is that initial path with slight upward angle is usually advantageous because of the smaller drag (in higher altitude) when in high speed. This results in oscilations of flight-path, which is apparently odd as optimal solutions.

View full abstract

Three-dimensional minimum-time turns are formulated and solved numerically as optimal control problems. The formulation covers the drag increase and the lift decrease due to sideslip. Inequality constraints are used to simulate the upper and lower bounds of thrust, angle of attack, sideslip and load factor. A state-variable constraint is included to treat the flight sustaining the corner velocity. Numerical results explain the effect of thrust, sideslip and initial velocity in optimal maneuvers.

View full abstract

Performance of the LE-7 engine, the first stage engine of the Japanese H-II launch vehicle, is estimated around its design point in a quasi-one-dimensional framework. The result shows that the gas dynamic properties are nearly in equilibrium at a high combustion pressure such as that in this engine. The exhaust flow pattern, the properties in the exhaust gas, and the flow rate of the cooling water to cool down the exhaust gas are estimated.

View full abstract