Greetings, everyone. Our fixed-wing UAV crashed during a take-off. We couldn’t understand the problem. We were having issues with this UAV, it was going slightly to the right(yaw) and crashed as shown in the video below. We were using CCW propellers. Our autopilot Pixhawk Cube Orange works perfectly on single-motored UAVs but we’re having problems with double-motored UAVs. Thanks in advance for your help.
Video: takeoff crash.mp4 - Google Drive
Logs: Takeoff Crash.bin - Google Drive
I had extremely similar experience with a smaller plane (except more spin).
The issue likely is that there is not enough yaw authority to deal with thrust asymmetry. Carefully check that both motors spin up at exactly the same time when moving throttle and reach similar RPM and thrust at a given throttle settings. Also check that props are correctly tightened and won’t slip in flight.
Later I would configure for differential thrust with ~5% gain instead of default 10% as it may be a bit much.
Did you calibrate the throttle range of both ESCs correctly?
If you can, try to get ESCs with telemetry, for example bdshot capable ESCs.
They report RPM back to the FC.
Another topic are the propellers. Your motor RPM is not necessary the propeller RPM.
It is not a good idea to fiddle with the direction of the motor because the nut only secures in one direction.
Copter Motors usually come in CW and CCW variants therefore.
As a last resort, try to launch with less power. You may have a stall on one propeller during launch.
There is a youtuber named ArxangelRC explaining setting up the UAV-X Clouds and mentioning that it’s overpowered. Maybe you want to reach out to this guy.
