New Large Quad Altitude Issues

Hey, thanks for reading this post.

I have flown my new project just a few times with pretty bad altitude performance in loiter each time.

Details of the build:
Pixhawk 2.1, Copter 3.5 and tried with 3.6 beta
Tarot X4 frame
T-Motor U7 420KV Motor
Tarot 1855 props
40-Amp T-Motor ESCs
6S 16AH Lumenier LiPo

I have been flying with no payload, so I believe the weight of the copter should be managed well. However, as the few logs linked below will show, I take off in loiter and attempt to hover. The copter keeps 2D position pretty well, but really struggles with altitude. It deviates 2-3 meters or so as it just hovers. It is just erratic enough that I do not feel comfortable with doing an AutoTune in AltHold mode. So currently this copter handles very poorly. The PIDs are all stock currently and I don’t feel too confident in my ability to guess at better parameters as I of course am trying not to crash this quad.

Here is a link to a few flights. In between different flights I would do things like try to cover the Cube with foam to try to help baro issues but nothing ever worked. I am somewhat suspicious of my Cube hardware. It will throw a ‘Bad Gyro Health’ at me every now and again.

If any could take time to look or notice an error in my build design, I would love to know. If pics or anything like that would be helpful, I’ll surely provide them.

For the ‘Bad Gyro Health’, try to recalibrate everything : compas, gyro and level calibration.
It would disappear :wink:

I’m trying to think now if I’ve seen bad gyro health since I reset the copter. I didn’t make it clear, but I actually loaded plane and then threw copter back on the board to clear everything and start over. So just today I went through a careful re-calibration of everything.

wait until the imu is heated up to 35° bevor the calibration.

I had similar altitude performance and a level and gyro re-calibration definitely helped.