VTOL cannot transition to forward flight (switches back to Q mode right after transition)

frog · October 5, 2025, 1:01pm

Hi everyone,
I’m having an issue with my VTOL (QuadPlane configuration) during the transition to forward flight.

When I command the transition, it starts normally — the plane begins pitching forward, the forward motor starts for a short moment, but then it immediately stops and the vehicle switches back to QSTABILIZE mode (vertical flight).

Sometimes it looks like it starts the transition successfully for a second, but then the forward motor cuts off and the VTOL “gives up” on transition.

Here’s what I’ve checked so far:

All motors and ESCs work fine during manual tests.
Battery voltage seems okay.
I have an airspeed sensor
Firmware version: ArduPlane 4.6.2
The issue happens every time I attempt transition.
tlogs

Rolf · October 5, 2025, 3:13pm

Please unlock your Google Drive. It would be more helpful to have a *.bin log file from the SD card than a tlog file.

Vince_Hogg · October 8, 2025, 6:03pm

Check your Q_TRANS_FAIL time is not too short or the AIRSPEED_MIN is not too high. .bin file would show the problem

frog · October 9, 2025, 8:05am

Rolf · October 9, 2025, 3:03pm

A *.bin file would certainly be better for evaluation. However, even with the tlog file, it is possible to determine that QLAND was triggered by your RC transmitter.

FLTMODE_CH is set to 8 and goes down to 965:

This corresponds to the flight mode set with FLTMODE1. In your case, this is QLAND.

Rolf