Perturbative effects of small thrust on the motion of an artificial earth satellite are investigated. The LAGRANGE planetary equations in Gaussian form are applied to determine the variations of the orbital elements. Also, equations of motion expressed in terms of different components of the thrust acceleration are used. It is assumed that the small thrust acceleration is a function of time and expressible as a linear combination of a polynomial and a composite set of all sines and cosines By the method of linear perturbations the equations are solved and the perturbative effects on satellite orbital elements are obtained. The terms in variations of orbital elements are of three types. They are purely secular, periodic and mixed secular types. Considering the gravitational disturbing function of the earth and the luni-solar disturbing function to deal with the combined effect, the theory is applied to the orbit of the geostationary satellite. Then the variations of orbital elements, the longitude, the latitude and the height based on the standard earth-ellipsoid are calculated. In addition there is a discussion of the method of determining the components of the thrust that maintains the longitude and the latitude of the satellite within a given tolerance band about a prespecified station.
A computer program SOLST 1 for calculating the lift distribution of oscillating wings has been developed based on our previous investigations. It will be possible to say by the numerical results that our method needs much fewer spanwise integration points than other methods to obtain the same degree of accuracy.
Analytical and experimental results on axial buckling of laminated composite circular cylindrical shells are presented in this paper. The results suggest the application of an optimum design method to determine the best fiber directions of the laminated composite cylinders. Simple conclusions about the best laminate configurations are not drawn from the application of an optimization technique. But several new buckling characteristics are found in the present analysis.
Tracking system that operates from nonstationary platform must have some means to stabilize the tracking axis for precision tracking. There are several methods used on a tracking axis stabilization. Among them, implementation of a free gyro pointing assembly which has momentum wheel that is an integral part of the innner gimbal assembly and that is orientated its spin asix parallel to the line of sight, is the most widely used methods for tactical missiles because of its simplicity and cost effectiveness. The paper describes two methods to improve stabilization of this tracking system by adjusting gimbal balance during accerelated condition and adjusting gimbal friction torque at an optimum level appropriate to the applied torque. The result shows one fifth improvement of the drift rate compared to the presently used tracking system, achieved more precision tracking.
A quasi-optimum flight path is determined to evade three dimensional obstacles. The procedure consists of solving two linear complementary problems, and is an extention of FUNK'S terrain following control into three dimensional space. The formulation includes upper as well as lower bound for flight-admissible space and gives a near minimum-distance path following terrain or obstacles.
Numerical results are given concering the minimum-time path through a region of position dependent winds' fields. Five (5) winds' fields are used: three (3) are defined analytically, while the other two (2) are composed from measured weather charts. Optimum paths thus obtained suggest the possibility of fuel saving to some degree when applied to flight across the Pacific Ocean.