Custom airframe for fixed wing aircrafts

How do we take into consideration the mechanical configuration of a fixed wing (wing span, tail length, control surface sizes etc.) when designing a new airframe for fixed wing crafts using Pixhawk?

When considering custom airframes for VTOL/Mulitcopters, I did some digging and found that there needs to be a file (.toml file) describing the orientation of the motors with respect to each other and the autopilot. This is very obviously important, since the autopilot needs to know where the motors are to effectively produce roll, pitch and yaw movements.

Is something similar needed for fixed wings as well? If so, what files need to be created/editted?

We are working on such physical description for FW airframes.

For now, you directly write the gains to apply to each flap for roll, pitch, and yaw control in a mixer file (*.mix).
See https://dev.px4.io/master/en/airframes/adding_a_new_frame.html for an example.

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Thank you for the reply! I shall take that approach as suggested.

@jlecoeur,

I curious to know what you guys are working on. We are our self currently working of the FW platform and are looking to reworking the mixer.

@AlexandreBorowczyk you are welcome to give your input, the discussion is happening on the PX4 slack on the control channel.

There is a draft PR for the implementation of control allocation https://github.com/PX4/Firmware/pull/13351

The format of the geometry description files for fixed-wing is still an open question, feel free to make suggestions!