In the present paper, the dynamic behavior of a rotor supported by externally pressurized liquid hydrogen bearing is theoretically investigated. The bearing treated in this study has 20 recesses arranged in two rows in a staggered manner and will be used in the liquid hydrogen turbopump of rocket engines for space transport systems. The equations of motion for a rotor are numerically solved using predictor-corrector scheme. The dynamic bearing reaction forces are calculated from the numerical solution of unsteady turbulent Reynolds lubrication equation. The transient responses of hydrostatic bearing under several operating conditions are presented. Furthermore, the journal center trajectories with imbalanced moment are examined theoretically.
Fixed based flight simulator experiments were conducted to investigate the influences of wideness of front view for pilot's roll control. In these experiments, the airplane's motion was considered as a single-degree-of-freedom system in roll, and three front views having different view-angle were provided. The results of these experiments showed that the pilot's roll control characteristics, and the pilot's sensing parameter and reaction time for rolling motion were influenced by the differences of wideness of front view in flight simulator.
This paper discusses a static stability theory for airplanes. The conventional definitions of static stability are neither clear nor systematic. On the basis of these situations, in the first report of this paper, a system of definitions on 6 static stability concepts was proposed, and two concepts of static flight-velocity stability and static angle of attack stability were studied. And in the second report, a concept of static pitch stability was discussed. This third report discusses on the three static stability concepts in sideslip, roll and yaw, and proposes that “dY/dβ<0, ” “dR/dΦ<0” and “dN/dΨ<0” should be used as the fundamental definitions, where R means rolling moment. The general criteria for these static stabilities are deduced from these definitions. From these criteria, “CYβ<0, ” “Clβ/CYβ>0” and “Cnβ>0” are obtained as the stable conditions. Finally, this report represents the whole summary of this paper.
We have developed a numerical method for design of minimum-drag supersonic wing thickness with constraints on total volume and wing maximum thickness position. The method is based on the linearized supersonic theory and is an extension of Kawasaki's method which deals only with total volume constraint. The maximum thickness position of the wing, a new constraint condition, is an important information from both aerodynamic and structural point of view. The addition of the constraint has considerably extended the design possibility and has actually produced many interesting optimum thickness families. Numerical examples are given for delta, gothic and arrow wings which confirm the usefulness of present design method.
Engineering Test Satellite-VII (ETS-VII) is a test satellite to perform in-orbit demonstration of autonomous rendezvous docking (RVD) technology, which will be necessary for advanced space activities in the early 21st century. ETS-VII successfully performed the autonomous RVD by unmanned space vehicle for the first time in the world. For an unmanned space vehicle to perform rendezvous to a manned spacecraft, safe approach is needed. So we paid special attention to designing safe approach trajectory. There are other important points for approach trajectory design, for instance, coordination with guidance and control accuracy, performance of navigation sensors, and operability, etc. In this paper, we introduce the points, and show the result of ETS-VII RVD trajectory design.
The potential-function guidance is applied to the autonomous formation-keeping of the eccentricity separation in the co-located many-satellite system. The acceleration resulting from the continuous and throttled thrust is formulated as a function of positions and velocities of all satellites. If these state variables are measured by on-board sensors, the maneuvering schedule can be computed in the respective satellites. A numerical simulation affirms the validity of the control.