Precursor experiment for an active true airspeed sensor.
The feasibility of an active optical true airspeed sensor was demonstrated with a coherent short-range Doppler lidar. Even at the long wavelength of 10.6 mum , aerosol events at the high altitude of 12, 000 m were measured. A comparison of the line-of-sight velocity obtained by lidar measurements with a conventional five-hole probe on an aircraft showed an excellent coincidence in the average value, although the lidar detected turbulence effects much more sensitively.
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