Solid State Angle of Attack Sensor

This sensor uses an ultrasonic emitter and an array of microphones to calculate windspeed and airflow direction without any moving parts. By comparing the phase of the recorded signal at each of the microphones, it is possible to calculate the delay or speedup caused by the moving airmass. I tested the sensor by fitting it to a car window with cardboard and driving around at different speeds: The plot shows that the phase change for each mic is correctly correlated with the position of the mic relative to the airflow direction and the ultrasound emitter. Mic 2 was furthest forward (see first image above), mic 5 was furthest back. Also, the separation of the phases increases at higher speeds, allowing the sensor to measure airspeed.

Because this is just a prototype, I used a Saleae logic analyzer to capture raw data from each of the mics, and extracted the appropriate DFT terms using Goertzel's algorithm (see notebook here).