Hello
Im interesting in using different uodate source rather than GNSS for velocity.
I thought the pitot could be used but i dont swe this option (i lnow it airspeed and not ground speed but it is better than nothing)
I saw the externalnav option but i dont understand which sensor could be used
A velocity source must provide ground speed and direction.
Pitot based airspeed provides none of the above.
And you should update to ArduPlane 4.5.7 ASAP