htotheunit
Member
Hello,
Today I was flying along with my hexa at a steady pace, when all of a sudden it began to rotate as though it had lost a rotor. Knowing the ground below was clear I began to slowly reduce the throttle to bring it down without causing too much damage.
Nothing appeared to happen when I reduced throttle then all of a sudden the aircraft rolled to the left steeply before rapidly and uncontrollably descending (definitely over the Wookong's maximum angle) it slammed into the ground damaging 3 motors (2 are salvageable, but i'd rather not risk it, they're full of mud), numerous props, cinestar gimbal and 3 arms.
I don't estimate the repair cost as too much (luckily) but as this hexacopter is an expensive piece of kit I have spent hours looking into possible causes. I have came up with the following:
1. Fault with Wookong or a speed controller on rotor number 5 causing it to power on full, causing the anti-clockwise rotation leading to the Wookong over compensating/getting confused. (Evidence is the sound of the video, and the purple line on the graph showing rotor 5 speed) however I have tested all speed controllers (albeit not in flight due to the airframe being knackered) and there appears to be no issue.
2. Engine malfunction causing slow rotating prop. I don't personally think this could cause the rapid descent seen, I have lost a prop before and managed to bring it down with no incident (replaced speed controller after this, problem fixed) Again, all engines have been tested (except for the knackered ones)
3. Some kind of issue/malfunction through interference or faulty IMU/compass data. I have had a couple of unexplained yellow flashing lights from the Wookong in the past leading to the craft leveling off until compass data was back, but I put this down to interference. All the cables to and from the IMU, PMU, Flight controller, GPS etc are correct, undamaged and besides the past couple of flights yellow light incidents have been flown may many times without incident.
Here's the video with the motor data from IOSD for rotor 4 (Yellow) 5 (purple) and 6 (green)
I didn't include the other rotors as they appeared to be functioning correctly, Motor 2 did have noticeably low throttle during the crash however I believe this was down to the FC not knowing what to do.
http://youtu.be/c2mgyTtCid4 (Full speed, no graphics)
http://www.youtube.com/watch?v=HAC1TTFd6-U (audio with motor power graph, the timing of the graph was estimated using the altitude stat, audio and video length, you can hear motor number 5 faulting first followed by rotor number 2)
Here's my spec:
Vulcan 1200 Hexa pro
Tiger MT3515 motors
Simon K flashed Maytec 40A opto speed controllers
Futaba super 8FG
DJI Wookong M running version 5.26 (latest version)
Gain settings:
Basic: Pitch: 270% Roll: 270% Yaw: 150% Vertical: 150%
Attitude: Pitch: 100% Roll: 100%
Any little bit of help that you can give, or theories you may have it would be greatly appreciated.
I'm stumped!
Today I was flying along with my hexa at a steady pace, when all of a sudden it began to rotate as though it had lost a rotor. Knowing the ground below was clear I began to slowly reduce the throttle to bring it down without causing too much damage.
Nothing appeared to happen when I reduced throttle then all of a sudden the aircraft rolled to the left steeply before rapidly and uncontrollably descending (definitely over the Wookong's maximum angle) it slammed into the ground damaging 3 motors (2 are salvageable, but i'd rather not risk it, they're full of mud), numerous props, cinestar gimbal and 3 arms.
I don't estimate the repair cost as too much (luckily) but as this hexacopter is an expensive piece of kit I have spent hours looking into possible causes. I have came up with the following:
1. Fault with Wookong or a speed controller on rotor number 5 causing it to power on full, causing the anti-clockwise rotation leading to the Wookong over compensating/getting confused. (Evidence is the sound of the video, and the purple line on the graph showing rotor 5 speed) however I have tested all speed controllers (albeit not in flight due to the airframe being knackered) and there appears to be no issue.
2. Engine malfunction causing slow rotating prop. I don't personally think this could cause the rapid descent seen, I have lost a prop before and managed to bring it down with no incident (replaced speed controller after this, problem fixed) Again, all engines have been tested (except for the knackered ones)
3. Some kind of issue/malfunction through interference or faulty IMU/compass data. I have had a couple of unexplained yellow flashing lights from the Wookong in the past leading to the craft leveling off until compass data was back, but I put this down to interference. All the cables to and from the IMU, PMU, Flight controller, GPS etc are correct, undamaged and besides the past couple of flights yellow light incidents have been flown may many times without incident.
Here's the video with the motor data from IOSD for rotor 4 (Yellow) 5 (purple) and 6 (green)
I didn't include the other rotors as they appeared to be functioning correctly, Motor 2 did have noticeably low throttle during the crash however I believe this was down to the FC not knowing what to do.
http://youtu.be/c2mgyTtCid4 (Full speed, no graphics)
http://www.youtube.com/watch?v=HAC1TTFd6-U (audio with motor power graph, the timing of the graph was estimated using the altitude stat, audio and video length, you can hear motor number 5 faulting first followed by rotor number 2)
Here's my spec:
Vulcan 1200 Hexa pro
Tiger MT3515 motors
Simon K flashed Maytec 40A opto speed controllers
Futaba super 8FG
DJI Wookong M running version 5.26 (latest version)
Gain settings:
Basic: Pitch: 270% Roll: 270% Yaw: 150% Vertical: 150%
Attitude: Pitch: 100% Roll: 100%
Any little bit of help that you can give, or theories you may have it would be greatly appreciated.
I'm stumped!
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