Skywalker X8 VTOL Oscillating at Landing

Hi everybody,

Would anyone be able to help me out with this one?
This is our maiden flight VTOL Skywalker X8, when I take off with QLOITER mode all motors spin fine and when I switch to AUTO mode its transition to FW normally. But when ended the mission, it starts oscillating while transitioning FW to multicopter flight. What causes this problem? Frame types, classes and motor spin directions are good, wiring seems good too, checked, the only thing that I am aware of that the power wires for ESC’s is quite long and maybe I get power loss?

Here’s the Log file and video

LOG : (BIN and TLOG)
https://drive.google.com/drive/folders/1mIVpfxrNTj4dj8qKapm7ikoAF81bCR5d?usp=sharing

Video:

Thanks in advance for time and assistance.

Combination of not stiff enough airframe, not enough power and voltage sag.

for long power wire for multicopter ESC’s does it affect?

Have you done an autotune in copter mode? Poor tuning and big, slow turning propellers can cause that problem as the motors react too slow to prevent the oscillation.

not yet, i’m just hovering test and it looks normal

Definitely do an autotune or tune it yourself if you know how. (At least turn Roll and Pitch P up from the default). While in a gentle hover with no demands it will look normal, as soon as there’s big demands from the flight controller then the problems show up.