A transfer function of an aircraft for some input and output has the relative degree of two or more. In such a case, it is known that unstable zeros, what is called limiting zeros, can appear when the system is discretized at a fast sampling rate. In an MIMO case, the inverted system can be unstable if the transfer functions have unstable limiting zeros. This fact makes it difficult or impossible to apply the MRACS to the design of the flight controller. In order to overcome this problem, application of the δ-operator is considered, and the numerical simulations show the usefulness of this approach.

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The lift on an airfoil flying over a wavy wall surface is calculated using a finite difference method, which was developed by J. Nakamichi to improve LTRAN2 evolved by W. F. Ballhaus & P. M. Goorjian. In order to apply this LTRAN2 version to our problem, some manipulation on grid-making-system is needed. First, cases of a flat plate over a flat solid wall are calculated to check the coding prior to the cases of a moving wavy wall. Second, aerodynamic characteristics of a flat plate over a moving wavy wall are calculated, and third its motion is investigated. The calculated results are compared with those obtained by the lifting surface theory. The agreements are quite satisfactory.

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A method of thrust control is shown for jetliner during approach. With this method, pilot can reduce airspeed deviation even or less compared with the operation under ATS (auto throttle system). In this way, airspeed can be controlled with adequate thrust change, without extra acceleration or deceleration. Flight record is shown to substantiate this.

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A feature of the Mission-Function (MF) control is studied in this paper. The MF control is a control algorithm compatible with the fundamentals of mechanics of flexible structures and employs the mission function. The mission function is a Lyapunov function which includes such mechanical information of the system as the Hamiltonian and also a generalized energy to improve the performance of the controller. This paper presents the necessary conditions for the MF control in a general form. Another purpose of the paper is to present a feature belongs to the MF control, that application of the control algorithm reduces to the design of an optimal regulator for the flexible structural system. Two examples for application of the MF control are shown through the use of the numerical simulation.

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A system dynamics simulation model is proposed for evaluating the effects of developments of the Solar Power Satellite (SPS) and the moon resource (³He) on the earth's ecological and econmics systerns. The relation between parameters in the model and simulation results is analyzed and the effective range of conditions in the developments of SPS and the moon resource is roughly estimated.

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Numerical investigation is performed on the error analysis of a vortex panel method in the two dimensional flow. The method uses step or linear vortex distributions on straight line elements. The airfoil is divided into a set of elements by three ways: semicircular-method, equispaced-method, and quartercircular-method. The following results are obtained: 1) The location of the optimum control point is the center of the elements for the step vortex distributions and the edge for the linear vortex distributions. 2) For dividing way of the airfoil, the semicircular-method is the best which is followed by the quatercircular-method and then by the equispaced-method. 3) When the airfoil is divided by the best way, the accuracy of the solution is first order in the elements size for the step vortex distributions and is second order for the linear vortex distributions. 4) For moderate number of elements (N<50), the solution of the method with the step vortex distributions is more accurate than with the linear vortex distributions.

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