A simple wind measurement control loop was written for the Bebop2 quadcopter. It tries to keep the roll angle at zero to align with the wind. It works well if there is a certain wind speed and clear, non-turbulenced wind. The wind speed is going to be determined later from the pitch angle.

The SODAR is set up. An array of loudspeakers pushes a very loud, audible series of pulses into the air and receives the response from the atmosphere with microphones.

The wind direction and wind speed can be determined based on the reflections at the air layers (having a different temperature).

At noon a cloud layer starts to cover the sky. It starts to snow in the afternoon. During supper we see that the weather should stay like that the rest of the week. There is some chance that a time window might open again during the night.

The measurements require a stable boundary layer. Clear skies without clouds and cold air would be ideal. We prepare for flights in the night, but in the end we don’t. In between we watch the rocket launch.