SOAR_POLAR_K does not accept a value over 0.500

Hi there,
I tried to change the value of the parameter SOAR_POLAR_K to fit my glider’s dimension but QGroundControl does not accept the value over 0.500.
Its default value is 25.600 and I wanted to change it to 58.4, but a value over 0.500 is profibitted.
Could anyone teach me why?

The range for this field as specified by the metadata from ArduPilot is 0 - 0.5. Is that incorrect?

You can use “Force Save” to override a save which fails validation.

Thnak you DonLakeFlyer,
I believe the metadata of ArduPilot is incorrect, because the definition of SOAR_POLAR_K is 16*weight/area where weight in kg and area in meteres squared. The weight/area usually takes a value of 1.5~5.5 for RC gliders. This means SOAR_POLAR_K takes a value of 24~88.
So the default value of 25.6 is quite reasonable.
Don’t you think it is strange that the default value exceeds the allowable parameter range?

Sounds like a bug in ArduPilot bug in parameter metadata. You should report it to them.

Hi RCnorm,

The metadata is fixed in the “latest” firmware revision. The range is 20 - 400.


Thank you Samuel_Tabor for your quick action.

@Samuel_Tabor, I have tested with 4.0.8 and 4.1 DEV but I don’t see that the metadata is fixed > in the options column the range is still 0-0.5

Hi Aticof,

It is fixed on the ArduPilot side, but as it’s relatively new the GCS applications need to be told to re-read the metadata to pick it up.

  • In Mission Planner, hit Cntl-F and select “Param gen”
  • In QGC, I believe the metadata is read when the firmware .apj file is flashed - @DonLakeFlyer will be able to confirm.

Again this should only be needed temporarily until the GCS built-in metadata cache is updated in future releases.

OK, thanks Samuel. I understand now.

QGC doesn’t do that. That only works for .px4 file formats and ArduPilot never supported parameter metadata in .px4 files.