I have been working on taxiing my recently purchased Model 4 before i actually fly it. I noticed that the airspeed indicator does not seem to work at taxi speeds. I did some testing on it, and it seems to operate fine putting gentle wind into it - but not at taxi. I am wondering if maybe I have not taxied fast enough yet. I have taxied fast enough to raise the tail wheel, but suspect I am only doing about 15 to 20 MPH. Does anyone know if there is a speed at which the analog airspeed indicator comes alive?