Hi all, I’ve been working on a large octocopter build for a while and have had some intereting issues in flight testing. Every time I’ve flown (always in loiter), the vehicle has been very stable and responsive after mag and accel calibration on the ground. However, once the vehicle has landed and taken off again from the same spot without calibration, it drifts quite a bit, and drift is accentuated with each control input, eventually leading to a crash. I’ve attached a log of a flight that went up, flew well for several minutes, and landed, and then took off and crashed shortly after. Pictures of the setup are included as well. Link to folder with pictures and log (too big to upload here): https://drive.google.com/drive/folders/1qjbHVcEFBb492Tl3aFoSz9YaYfCIdReH?usp=sharing
Hardware overview: Blue Cube Pilot H7 (V4.0.7); Herelink ground/air station; MRo Location One GPS/compass via CAN; Luminier 36A BLHeli_32 ESC x8; T-Motor Antigravity 5008 Motor x8; T-Motor 16x5.4 Carbon prop x8; 6s 10000mah Tattu Plus battery x2; Mauch 400A PDB.
From my experience, drift in loiter usually has to do with GPS lock, however, the vehicle was always connected to at least 25 sats and HDOP ~ 0.5. Another suspect was EMF interference, but I moved the high current wires away from the accel/compass and behind a sheet of carbon fiber for shielding, and the issue persists. Changing from the MRo Control Zero F7 autopilot to Blue Cube H7 also did not help. My main culprit at this point is compass errors, but it’d be great to hear ideas from other people on what may be going on. Crashing this thing is expensive so I want to be a little more sure of my next fixes before I fly it again. Any tips or ideas are much appreciated, thank you!