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?
Your picture shows relative good correlation between GPS-speed and Airspeed, so why you think you had a problem with the airspeed sensor.
Your log-file is restricted to a user-account, please provide the log without user restriction
1- Log access is made public
2- Why IAS airspeed drops to 14-15m/s at specific intervals & sometimes for a longer perios of time? Such IAS drop is not observed in other flts.
As @Juergen-Fahlbusch commented, I agree the correlation looks good. I’ve also provided a sample of the pitch vs airspeed. It also looks correct. Higher airspeed, lower pitch. Lower airspeed, higher pitch.
I did notice that when the airpseed sensor goes offline, there is a speed change. Without airpseed the plane will revert to the TRIM_THROTTLE value. When the airpseed is working the the plane is following the TRIM_ARSPD_CM setting of 2000 (20m/s), but when the airspeed stops working it drops to TRIM_THROTTLE of 50%. I suggest that is too low for this plane if 20m/s is your ideal speed, and that TRIM_THROTTLE should be closer to 60 or 65. (not knowing the plane or it’s setup I can’t make any suggestions here, but that does sound a little higher than ideal)
So the plane is doing what it has be told to do (maybe not what you wanted).
What I can’t tell from the log is why the airspeed sensor stops working. That is a mechanical/physical problem.
2024-09-10 07:05:55.869 Airspeed sensor 1 failure. Disabling
2024-09-10 07:06:47.463 Airspeed sensor 1 now OK. Re-enabled
Arduplane does not require an airspeed sensor, however it will improve performance. When a sensor fails (or is not used) Arduplane will revert to a synthetic airspeed. Consider it a safety feature.
