Speed limit in copter SITL

Hello everyone
When the frame_type was 0, I played with the angle_max, wpnav_speed and mot_spin parameters to reach the speed I wanted in the copter simulation. And I increased my speed from 10m/sec to 19m/sec at the beginning. But then I changed the frame_type to 1 and looked again, this time I saw the maximum speed as 13m/sec. I can’t make the speed more than 13 now. It doesn’t increase. In addition, the oscillation has also increased a lot. Why is the frame_type so effective? What should I do to increase the speed? Please help.