The behavior of three-dimensional boundary layer on swept wings is an important research subject for the future high-speed airplane. The purpose of the present paper is to study controllability of boundary layer transition by suction. Experiments are done by using a closed circuit wind tunnel at Tokai University. The swept wing model with a latch for variable sweep angle at a root is mounted vertically in the 1.5m×1.0m test section. Suction is applied through the perforated surface, and flow velocity of the suction is variable. Two velocity components measured by the twodimensional hot wire anemometer with computer controlled three-dimensional traverse system. At various sweep angles, the velocity inside the boundary layer is measured, and the data are investigated to obtain the relation between the sweep angle and the effect of suction.
Fixed base flight simulator experiments were conducted to investigate effects of control system dynamics on the handling qualities of an airplane. Breakout forces and force gradient ratio to control displacement were changed mechanically by the ELECTRO-LOAD equipped to the simulator recently. Relationships between control forces and stick positions were measured, and both breakout forces and force gradient ratio were determined experimentally. These control system dynamics were changed parametrically in the flight simulator tests. The control of the longitudinal pitch angle was selected as the flight maneuver of the airplane. Time histories of both the pitch angle and the pilot control were obtained, and analyzed systematically. Good insight into the effects of the control system dynamics on the handling qualities of an airplane was obtained.
Optimal flight trajectories of a supersonic transport are investigated to reduce the effect of sonic boom. By developing a sonic boom predicting program, cost functions are formulated to evaluate the effect of sonic boom to a terminal area model. The cost functions are tried to minimize by the numerical optimization method which utilizes the simulated annealing techniques named the Hide and Seek method combined with the R-Tabu search algorithm. The proposed optimization method has the capability in finding the global minimum without gradient information. The computed results indicate the efficient accent trajectories by considering both the weighted integration of the sonic boom intensity and the maximum value of the intensity.
Scramjet engines are tested by using the RamJet engine Test Facility (RJTF) under Mach 4 to 8 conditions, where a storage heater (S mode) and a combustion air heater (vitiation: V mode) are used to raise the air temperature. The effects of air heating methods on scramjet engine performance were investigated using a chemical kinetic code, LSENSAt first, dependence of dissociation time of O2 was investigated to evaluate the amounts of radicals supplied to scramjet engines in test facilities. Residual radicals in the S mode, the V mode, shock tunnels, were evaluated for the various nozzles. Then, autoignition criteria with radicals and H2O addition were calculated for a scramjet flow. Then the possibility of autoignition in boundary layers was examined for M 6 and M 8 conditions. No differences in the S and V modes were found in chemical and flow fields in the engine tests in the RJTF.
This paper deals with a general and efficient computer algorithm to simulate multibody dynamics with configuration changes, which are characterized by a change in the number of degrees of freedom and/or in the constraint equations of multibody systems. These systems are called "reconfigurable multibody systems." When we analyze the capturing and removing process of the damaged satellites by space manipulators, the reconfigurable multibody dynamics must be considered. Dynamics of such systems has not been studied well though it is indispensable to develop the wellfunctioning automatic machines and robots in space as well as on the ground. We introduce the method to express the timevarying system topologies based on the graph theory and the linked list, and reformulate the efficient dynamics algorithm based on the "order n algorithm" for forward dynamics of closed-loop systems. In this paper, we expiain the above algorithms and implement a computer program using the object-oriented programming method. Moreover, we examine how to apply these pragrarns to space systems.