Airspeed is always 0

My plane has no Airspeed sensors but has GPS. I think that airspeed could estimate from GPS, but it is always 0.

Anyone could help me?

I set FW_ARSP_MODE as normal

please upload a logfile

this is my log

I know what. I don’t hasve airspeed but FW_ARSP_MODE set 0 (normal),This causes the airspeed to be 0. How can I use Groundspeed as airspeed?

You have very bad magnetometer data which you need to fix before worrying about airspeed.
Make sure to:

  • mount the magnetometer far away from the powercables.
  • twist the power cables
  • align the magnetometer with the autopilot as well as possible
  • calibrate far away from any metal structures etc