VTOL Transition not starting in AUTO (QTUN.Trn stays 0 despite airspeed > AIRSPEED_MIN)

ArduPlane VTOL Plane
1

Hello everyone!

I’m testing a dual motor tailsitter in SITL with a mission that starts with VTOL takeoff and then a waypoint. The aircraft takes off and gains altitude endlessly, but never transitions to forward flight. In the logs, QTUN.Trn stays at 0 the whole time even though airspeed is well above AIRSPEED_MIN - the transition doesn’t even begin. I’ve played with the usual parameters (Q_TAILSIT_ANGLE, Q_TRANSITION_MS, etc.), but it makes no difference. In manual modes like QStabilize and FBWA everything works fine. I’ve attached the bin log and mission screenshot. If anyone can point out why the transition condition isn’t triggered in SITL, I’d appreciate it. Thanks.

(version ArduPlane V4.7.0)
BIN log: https://drive.google.com/file/d/1FAWEgrTuP_UkGanXPlQnE8373xafOBiq/view?usp=sharing

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2

I noticed that if I manually set a waypoint from the actions tab, the aircraft transitions to horizontal mode. But why does this not happen automatically?

3

How are you launching SITL? The built in tailsitter simulation model is not very good.

4

I made my own simple model in game engine and connect to it via JSON UDP interface. It works in horizontal auto, but doesn’t transition.

5

Tailsitters to work well in other with other simulators such as realflight. I suspect its a problem with your simulator, or the ArduPilot configuration for your vehicle.