Fig. 1. Anemometer calibration. (A) A servo motor driven at up to 300 Hz drives a balsa wood plate. The air disturbance generated as a result of this oscillation is clearly registered as a pulse in the anemometric record (B). Thus, the anemometer has a frequency response of at least 300 Hz. (C) The time taken by the anemometer to reach its steady value has a time constant of 0.0103 s, nearly 1/4 of the wing period (ca. 0.04 ms). A=airspeed; the red line indicates the exponential function A₀(1-e^t/); see text for details.