Crash analysis

Running Pixhawk, Ardocopter 3.5.1 with FR Sky Taranis radio. Everything previously working fine.
When I attempted a takeoff in loiter mode today my machine dipped left & right then dipped forward & aft. I tried to nreturn it to the ground & it rolled over.

Powered down & tried again after a break & same thing occurred again.

Changes before this flight were enabling simple mode on channel 8.

Ive attached t log file (crash occurs at 48%) as well as other log file.

Would really appreciate some expert analysis.

Thanks in advance

Would really appreciate some assistance on this? Particularly when everything was fine prior to enabling simple mode on Loiter.

Thanks in advance

Confirmed SIMPLE loiter to be working in 3.1.5.

Roll and pitch diverge badly from demand and oscillate at ~1.5 hz, which would make me suspect your RATE_P or STB_P gain terms.

Is your copter lighter than when it was tuned, or have you given it a new battery perhaps?

I recommend backing off STB_PIT_P and STB_RLL_P to the default of 4.5, RATE_PIT_P, RATE_PIT_I, RATE_RLL_P, and RATE_RLL_I by 20% to .072 and running an autotune with the copter at its minimum flying weight - no cameras, gimbals, extra batteries or payload.

thanks for your response Jonathon, very much appreciated.

I’ll give that a try. The only change to my machine has been upgrading software & attempting to change a switch on my fr sky.

I’ve never done an auto tune as I purchased the machine second hand from a reputable dealer. I’ve been through about 8 battery cycles (3 batteries) & experienced never experienced the same issue before.

Shall let you know how I go.