Airspeed sensor

I am setting up a new Ardupalne and I notice the airspeed sensor on the bench is quite unstable.

There is a gentle (temperature?) drift that after 5minutes is about 6units (ie 6m/s) and a random variation of about 1 to 1.5units on top of that.

If I do a preflight calibration then the average speed falls to about 2 +/-1 units.

Is that normal or do I have a faulty unit. I have noticed that the pwoer supply from the APM 2.5 is noisy but am not sure if that is causing the variation.

Peter

I am setting up a new Ardupalne and I notice the airspeed sensor on the bench is quite unstable.

There is a gentle (temperature?) drift that after 5minutes is about 6units (ie 6m/s) and a random variation of about 1 to 1.5units on top of that.

If I do a preflight calibration then the average speed falls to about 2 +/-1 units.

Is that normal or do I have a faulty unit. I have noticed that the pwoer supply from the APM 2.5 is noisy but am not sure if that is causing the variation.

Peter
APM 2.5, Arduplane 2.77

Absolutely normal.

Noise levels by barometric speed readings depend on the measured airspeed. Air speed sensors are unusable at low speeds due to the noise and drift. It will perform better at higher air speeds.

Thanks I was hoping it was normal - saves me replacing the sensor for another that gave the same result!

Peter