In this paper, a new guidance law for a missile against an accelerating and turning target is presented. When a missile axial acceleration is constant and a target is maneuvering with a constant acceleration, there exists a rectilinear collision course. The guidance laws presented guide a missile so as to fly along the collision course. First, two theoretical guidance laws are derived from the idea based on proportional navigation. Since it is very difficult, however, to realize these theoretical guidance laws on most existing tactical missiles, this paper also shows a method for simply implementing them. The performance of the guidance laws presented is compared with that of proportional navigation or augmented proportional navigation using simulation studies of a simple model of a short range air-to-air missile. The simulation results show that the guidance laws presented are far superior in performance to proportional navigation or augmented proportional navigation.
As one of hypersonic propulsion systems, airframe-integrated scramjet engines of NASA Langley type are promising. These engines are consist of several modules, each of which composed of a compressor, a combustion chamber and a nozzle. When some disturbances occur in one module of the airframe-integrated scramjet engine, its influences are thought to propagate to other modules. In this study, it is investigated numerically how shock waves caused by thermal choke in one module propagate upstream and how they influence adjacent modules. The calculations are carried out in the two-dimensional compressible inviscid flow model using explicit symmetric TVD schemes. It is shown that shock wave generated in front of one module extends and that it blocks the flow coming into the adjacent modules quickly, which makes the modules unstarted.
A method of rapid automatic “optimal” design of a propeller combined to an engine is presented for unducted cases. The whole data, such as diameter, blade pitch angle, blade number, rotational speed, and practical propulsive efficiency are determined, for various design points. Use of a personal computer is suitable for this method.