I am part of a team that working on a prototype for a heavy lift drone. I am using the Holybro Pixhawk 4 FC and I am having trouble trying to fly the prototype. I am thinking that problem is in the air frame mixer, I am using the generic 500 mm X quad air frame, the prototype is 14 in diameter. Big difference, so I am thinking that I need to reduce the Gains in the rate controller a lot and start over bringing them up very slowly. I have done all of things that the article talks about on getting ready to tune the drone.
Any thought would be great.