Re: airspeed indicator for speedo
It was late yesterday, calm wind conditons.
Thats a Hall Bros wind meter. Been used for years on hanggliders and ultralights.
The disc floats on a wire in the tapered tube, The tube has a small air inlet bottom front and an outlet on top. The increasing wind pressure dloats the red disc higher to indicate speed.
They are known to be very accurate windspeed indicators. They were about $24 a few yrs back, with choice of long or short mount and clamp.