After watching a movie clip of my plan flying on auto using the airspeed, I see that at times it oscillates pitch up and down, while increasing and decreasing the motor revs continually.
This seems to only happen with the Airspeed sensor connected.
I looked at the airspeed values in the NTUN log and found this:
The airspeed periodically drops down to zero suddenly, and then back up.
Is this normal? Is there something wrong with my sensor?
Some of my thoughts:
The airspeed indicator is not accurate at airspeeds that are really really low. If you're just flying really really slow it might just drop to 0.
The airspeed indicator gets calibrated at startup. If the airplane is in the wind when you plug it in, then the airspeed will be offset.
If it's sporadic in calm air then there's a problem with it. If you're flying upwind and your groundspeed is higher than your airspeed then there's a problem with it. If you can't get it pretty high (15+) by blowing on it, there's a problem with it.