Today I did several flight tests with my Mini Quad 210mm (it’s not a racing drone).
1st Test.
With the parameter GND_EFFECT_COMP set to value 1, and in the flight mode “PosHold” I made a takeoff, configured for a height of 2 meters.
Results:
Altitude Hold, very bad.
2nd. Test.
With the parameter GND_EFFECT_COMP set to the value 0, and in the flight mode “PosHold” I made a takeoff, configured for a height of 2 meters.
Altitude Hold, very bad.
3rd Test.
With the parameter GND_EFFECT_COMP set to value 1, and in the flight mode “PosHold” I made a takeoff, configured for a height of 5 meters.
Altitude Hold, acceptable.
4th Test.
With the parameter GND_EFFECT_COMP set to the value 0, and in the flight mode “PosHold” I made a takeoff, configured for a height of 5 meters.
Altitude Hold, acceptable.
5th. Test.
With the parameter GND_EFFECT_COMP set to value 1, and in the flight mode “PosHold” I made a takeoff, configured for a height of 15 meters.
Altitude Hold, Excellent
6th Test.
With the parameter GND_EFFECT_COMP set to the value 0, and in the flight mode “PosHold” I made a takeoff, configured for a height above 15 meters.
Altitude Hold, Excellent
Conclusion: In my case I have come to believe that the parameter GND_EFFECT_COMP is not having any effect.