Standard VTOL

Hi, I´m developing a standard vtol and I´m having trouble with the motors behaviour when I turn them on before takeoff. As I increase the thrust, some motors start to lose power and this causes the aircraft to spin as if it was trying to make a yaw maneuver. Sometimes only 3 motors are operating and sometimes only two. The battery I´m using is suposed to provide enough power to feed them all. I´m using the QuadPlane VTOL airframe in PX4 but I don´t know if its the software or if something is wrong with my electric system. I have tested my aircraft as a quad X and it seems to behave ok. I have this issue only when I upload the VTOL airframe. Does anyone know what can it be?

More details of your build would help, i.e. motors make and model, props, battery, firmware version, takeoff weight, etc. You can also upload your logs for analysis.

Good luck.

I´ve changed my airframe for the Fun Cub Quad VTOL and it solved the problem. I´m now having problems with the magnetometer due to interfereces with the thrust but Its one step closer.