Today, I conducted a test on a system with the following specifications:
T motor P80 120 KV motor
30-inch propeller
Coaxial QUADX8
Flame 80A HV ESC
Cube Orange FCB
During an endurance test with a 14kg payload (AUW was around 44kg) at 10m altitude in position hold flight mode, the drone experienced a descent after 16 minutes of hovering. A “potential thrust loss (2)” message appeared, and I observed that motor number 2 stopped in mid-air. After landing, all other motors were spinning except for motor 2. I couldn’t determine the issue from the log.
I greatly appreciate all the efforts of our fellow members.
There’s a drop in current (and rise in voltage) at the same time as #2 went offline. The FC was commanding an output, so the problem is not in the controller or it’s settings. Check wiring, test the ESC/Motor, go over all the basics. Were the ESCs hot when it landed? How are the motors? The overall voltage was getting low, so you might want to check there is no low voltage cutoff set in the ESC (I admit I don’t know if that’s possible on those ESCs)
The PWM values are at the high end to start the test, 1600, and as the flight continues they keep climbing. Normal as the voltage drops. However this suggest the drone is on the heavy side and parts are getting taxed. If you were flying around, not just hovering, you may find that you might starting having control issues as motors are reaching their max values.
@Allister Hey, thanks for reviewing and commenting. I agree that the copter’s AUW is on the higher side. After landing, the motor temperature was a bit high, but those motors tend to heat up a lot. The ESCs are located in the middle section, so I couldn’t access them. However, once it landed, I checked the arming and disarming, and found that the motors are running.
This is never easy to determine. Rule everything else out 1st. Motor 2 was working harder than the others for the entire flight so over temp perhaps on the motor or on the “down in Flames” ESC’s.
I can’t really honestly answer that with 1st hand knowledge so take my quip as just a joke. For that size craft you have few choices for “industrial” ESC’s.
That is true for both C2 and C8 motors, apparently the ESC with the No. 2. motor was not up to the task. I also see that the copter was really on the heavy side with these motors, the manufacturer recommends 30 kg with a quad and 35 kg with a hexa frame. The X8 parallel setup is even worse as the lower motors are in the propwash of the upper ones and cannot operate as efficiently as if they were separate.
