Quadplane Hover Tests Done, Tuning Advice Needed Please

Hoping for some guidance here: I’ve done some basic tests on my Quadplane in rotary wing mode (no transition as yet) and I’m looking for some tuning tips. Whilst I have 3 fixed aircraft flying well on Pixhawk, I have very little experience with Copter firmware (all my rotary wings are DJI). The aircraft was well baselined in fixed-wing mode, having done 10+ flights (before the Quadplane mods). I have tried Qhover and Qstabilize modes and these are my observations:

  1. The aileron/bank control and pitch controls are very sensitive to stick input – do I lower the Q_A_RAT_RLL_P and Q_A_RAT_PIT_P?

  2. I am find that I need to maintain forward stick to hold position – is there a way of fixing this?


Did some ore tests today, at first I tried lowering Q_A_RAT_RLL_P and Q_A_RAT_PIT_P all the way down to 0.1 but discovered it was not very stable. I then put them all the way back up to 0.25 (default values) and things were much better. I played around with QHover and QLoiter modes and discovered that the hypersensitivity to stick input is only occuring in QStabilize mode so I guess I just won’t use that in future. So, all is fine, apart from the tendency to drift backwards in non-GPS modes (QHover and QStabilize). The booms are pretty much level with the the lower surface of the wing and the plane was well baselined in it’s fixed-wing only configuration, so I’m not quite sure what to do. Not a major problem as I can just use QLoiter most of the time (except when transitioning from fixed wing flight to rotary wing, as that will supposedly stress the airframe).

The rate parameters (the ones starting with Q_A_RAT_) are not the right ones to reduce the sensitivity to stick input. A log would tell me more, but I would instead suggest:

  • lowering LIM_ROLL_CD and LIM_PITCH_CD. That will lower the demanded angle when you move the sticks in QHOVER. I will be changing it to use the minimum of Q_ANGLE_MAX and those values, but for now the LIM_* parameters are the key
  • if the demanded angle is OK but you don’t like the rate it rolls at then lower Q_A_ACCEL_R_MAX and Q_A_ACCEL_P_MAX. They are the roll and pitch rate limits in centidegrees/second

Posting a log could be helpful.

Thanks, I’ll try changing Q_A_ACCEL_R_MAX and Q_A_ACCEL_P_MAX in that case.
Can you remind me - is it log or bin file that I need to pull?

Many thanks,

I’ve pushed the fix for Q_ANGLE_MAX into master. Previously if you asked for maximum roll in a quadplane you would get LIM_ROLL_CD. That is often quite high (50 to 60 degrees). That makes it far too sensitive to stick movement.
Now maximum roll will be the minimum of Q_ANGLE_MAX and LIM_ROLL_CD. So you can lower Q_ANGLE_MAX to limit angles in QHOVER and QSTABILIZE. The same applies to pitch.

bin files are preferred


I couldn’t upload the .bin file to this thread, so I have uploaded it to dropbox here:

Hopefully you can retrieve it?

I’m interested to see what you find. Note that I have dialled down Q_A_ACCEL_R_MAX and Q_A_ACCEL_P_MAX to 7,500 which seems to have softened the responsiveness in Qstabilize and Qhover modes slightly. But I still prefer the much softer feel in Qloiter. Can you check the default values for these parameters when Quadplane is enabled? The 110,000 value equates to 3 full rolls per sec, if it’s centidegrees?

Had a slightly scary moment when RTL was triggered, as I was flying the packs all the way down to check duration. Fortunately I did not have the forward motor prop on and toggled it out of RTL (testing on a football field, but it’s in the middle of a residential area!)

Appreciate you are a busy man, so no rush.

Thanks again for everything you are doing to support (and lead!) this community.


@tridge I was able to use Q_A_ACCEL_R_MAX and Q_A_ACCEL_P_MAX to soften the controls in Q Hover but in Q Loiter Q Land and others that use GPS repositioning seems it does not use these 2 parameters for input. In any other Q mode the input is really sensitive to the point that over correction is really easy and dangerous some times. In Q hover it is really stable and controllable. Is there another setting to use to soften input for these other modes? Thanks again for all the work you guys do.

@TTGold have a look at the tuning doc here:

@tridge. Thanks for the reply. I actually tried to follow this specific doc all the way through. This is how I was able to get a flyable quadplane in vtol. I did end up lowering the accel parameters all the way down to 18000. The only thing I haven’t tried is setting the Q_A_ANG_LIM_TC. Do you think this would make a difference in QLoiter? Overall the tune seems pretty good other than just the rc input sensitivity in Qloiter now.

With the latest firmware how much of that list is done with the Autotune? With future updates how much can be done automatically, such as Notch filtering?