Fast temperature and true airspeed measurements with the airborne ultrasonic anemometer-thermometer (AUSAT)

An airborne thermometer-anemometer with fast response is designed and built using the well-known sonic anemometer-thermometer technique. The shape of this new airborne sonic sensor, without the conventional style probes, is a cylinder with its axis colinear to the aircraft's longitudinal axis. The true airspeed and the air temperature are measured in the same volume. A previous paper described a preliminary version of this sensor and presented data of flight tests obtained on board Meteo France's Cessna 206. This new paper shows an improved sensor and the results obtained on faster aircraft such as the CNRS-INSU's Fokker 27 and the Meteo France's Merlin IV. First, the sensor and the principle of the measuring method are described, then data collected during several flights from 1996 to 1998 are presented. Although this new thermometer-anemometer is not completely calibrated, it provides mean data very close of those measured by conventional sensors but with a response time 30 times shorter.