Q_assist_speed and tiltrotors

Hello all, I have a question about tiltrotor behavior.
I’m working on a custom-designed aircraft of a small size and fairly high wing loading. It’s a Quadplane configuration with the front two motors tilting on a normal servo, and the rear two stationary. I haven’t flown it yet, but based on my knowledge of RC aircraft, I suspect it’s going to have a relatively high stall speed. What I want to know is this:
How do tiltrotor aircraft handle Q_Assist_Speed and Q_Assist_Angle?
Obviously, the back two motors would be able to assist easily. But what happens with the front two? If I set a Q_assist_speed or _angle, will those motors do anything? Will it partially tilt them to get assist while maintaining forward speed? If so, how does it determine what angle to tilt to? I’ve read through the Ardupilot.org documentation on quadplanes thoroughly, but I can’t find any reference to how tiltrotors behave with these parameters.

Works properly since 3.9.2beta2, see:


Thank you for the quick response! So, what I’m gathering from your video is this: Q_assist_speed on a tiltorotor works more as a “safety net” than an actual “assist”: Upon dropping below the speed threshold, it tilts the motors and essentially does a full transition while maintaining FBWA controls: throttle is forward, not up. Applying more throttle causes the aircraft to transition back into forward flight.

I do have a follow-up question: Is it possible to have an in-between scenario? As in, would it be possible to maintain forward flight at a speed below the aircraft stall speed. To only tilt the motors part of the way, so the thrust has both a forward and an upward component.

Correct me if I’m misunderstanding something here. This is my first experience with vtol of any kind, so I’d like to figure this sort of thing out BEFORE I flip that flight mode switch rather than after.

I have not tried it yet, but it should be possible

If you do attempt it, I’d like to hear the results. It will probably take me a few weeks to get my own build flying well enough to try it.

No sure if the motor fully go back or tilt diagonally I have my assist speed a little high and yesterday looking at video the plane did activate the assist for a short period of time and I didn’t even noticed. the airspeed came back up nicely with any noticable change in flight behavior.

When I do a transition intensionally my plane does pitch up a little . But didn’t notice that either.

So I guess it works pretty well…

Sorry I know this is a super old post! Did you happen to figure out how to tilt the motors part of the way to maintain forward flight below the stall speed of the aircraft? I’m trying to do something similar with a tilt rotor tricopter and I’m struggling to figure out if this is possible. Thanks!