Hi everyone,
I’m currently working on tuning the VTOL transition for my Heewing T2 Cruza VTOL, which is a tri tiltrotor. I’m encountering serious stability issues during the transition phase from multicopter to fixed-wing.
In real flight, the drone pitched down aggressively right after initiating the transition and crashed into a field. I’ve attached the flight logs from this crash for reference.
I’m experiencing very similar behavior in simulation using the PX4 “tiltrotor” model in the Gazebo library. During transitions, the vehicle consistently drops several meters before recovering, showing the same nose-down tendency.
I experimented a bit in simulation and found that extending the transition time to more than 10 seconds and setting VT_TILT_TRANS to a high value (e.g., 0.7 or above) seems to reduce the severity of the dive, but these adjustments feel more like a workaround than a real solution.
This behavior doesn’t seem ideal, especially when I compare it to ArduPilot, which seems more commonly used on VTOLs (and is recommanded by Heewing for this platform), where transitions are almost instantaneous and much smoother by default.
I’d like to understand:
- What could be causing this nose-down behavior during the transition?
- Are there parameters I should look into tuning to fix or reduce this issue (beyond just increasing transition duration)?
- Has anyone experienced similar problems, particularly with tri tiltrotor setups?
Any insights or suggestions would be greatly appreciated.
I’ve attached:
- The crash flight log (The crash occurs near the end of the log, shortly after the transition to fixed-wing flight begins.)
- A log from a simulated transition using the PX4 tiltrotor model (4 motors)
Thanks in advance for your help!