Large Art Drone - unstable behavior with attachment, Log attached

cyberpatrolunit · August 4, 2020, 9:27pm

Hey there! Thanks in advance for taking a look at my request for help.

I have a large quadcopter on 3.7dev, it has been tuned but I am unsure if it needs to be tuned (or sable enough to tune) with the attached artwork.

1000M Quadcopter
100kv motors
30" Prop
Pixhawk 2.1 Cube
6S

My main goal is to have this craft safe to fly, it’s quite unstable with the attachment.
The copter seems very stable without the attachment, but it’s not very fast or nimble due to it’s large size.

Would it be safe to re-tune with the attachment?
Is the craft underpowered ?
Should I consider an X8 over a quadX ?

Here is a flight video with the payload attached, might help in referencing the attached log #48:

Motor PWM without attachment:

Motor PWM with attachment, also seen in the video link.

Link to download the log:
https://drive.google.com/file/d/1yRkT50e0B7BKKfMzqQOalaYOtcxKgjyQ/view?usp=sharing

Here is the auto analysis info:
Size (kb) 30529.916015625
No of lines 351323
Duration 0:18:55
Vehicletype ArduCopter
Firmware Version V3.7.0-dev
Firmware Hash 7c65d89c
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = WARN - Moderate change in mag_field (34.13%)
Max mag field length (552.47) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.25, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = GOOD - Motor channel averages = [1307, 1308, 1293, 1295]
Average motor output = 1300
Difference between min and max motor averages = 15
Test: NaNs = FAIL - Found NaN in CTUN.DSAlt

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - ‘MAG_ENABLE’ not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = UNKNOWN - No CURR log data

manavgandhi17 · August 5, 2020, 5:49am

This seems like it is caused by the motors not having enough torque to command roll/pitch for movement or wind reaction. This is usually caused by a low voltage motor prop pairing - which I think is the case with this build. 6s is a bit too low for these motors to react properly with 30" props. I would try upgrading to the maximum voltage that your system can support - ideally 12s.

cyberpatrolunit · August 5, 2020, 6:08am

The good news is:

system is built and wired for 12S. I reduced the 4X @ 12S lipo to 2X @ 6s for weight, I suppose I could try the 12S configuration again.
Props and Motor are paired according to spec on T-Motor, I believe I am using P-80 100kv with 80amp flame ESC and 30" T-motor prop

Any other findings in the Log? I was still getting similar behavior on a 12S voltage with the artwork attachment.

manavgandhi17 · August 5, 2020, 6:20am

So, I am looking at the bin you provided and it is stating that the voltage is around 45V. So was this flight with a 12S setup?

Looking at the logs it seems like the desired pitch/roll was not being achieved (by a high amount) - so it makes sense why it “crashed” like the video shows. Don’t know if this was caused by a large wind gust or just based on a bad tune. A longer flight log without payload and some mixed flight would be nice - but I understand that it may not be possible.