We did a long flight for a distance of a Quadplane with a wingspan of 3 m. It was flying at 20-22 m/s as programmed but after an hr its airspeed started giving reading of 14-15 m/s and after a while it became normal.
This again repeated a few times in the flight but with variable frequency. We changed airspeed sensor and did another flight but again observed similar behaviour.
Queries:
1- Why this happening & whats the fix?
2- Why the lower value is 14-15m/s and not below?
3-WHy changing Airspeed sensor have not fixed the issue?
Datalog is in the attachment.
Datalog