Abstract
Seven configurations of two-di rectional wind vane, i.e., a device to measure simultaneously both horizontal and vertical directions of wind, are tested in wind tunnel, their periods of oscillation and time constants are evaluated and reduced on the basis of simple geometrical and kinematical relations. For the spinning vane the gyroscopic and Magnus effects should further be considered. For the vanes with axial asymmetry and for those with axial symmetry beyond certain amplitude, the phase difference between horizontal and vertical oscillations must be tolerated. For all vanes the period and the time constant of oscillation, i.e., the time during which the initial amplitude decreases to 1/e are both of the order of one second per 10 m/s wind speed and diminishes in inverse proportion of the wind speed. For other vanes with different geometrical and kinematical configurations, simple reduction formulae are given.
