Almost crash during landing due to RTL on Q_plane (again)

[Lorenzo_Pessah (Pier Lorenzo Pessah)]

Hello there,

Once again I was very close to crash my Vtol plane due to AP switched to RTL while it was in Q_loiter at very low altitude.

Please check attached log and setting file.

I hope there is a parameter to set but I’m unable to find it otherwise we need to have a parameter to setup the minimum altitude in which the system is allowed to switch from -previous mode- into RTL with conversion.

Hawk VTOL AP4.2.1 15-07-2022.param (20.6 KB)

Log file : 15-07-2022 - Google Drive

[Lorenzo_Pessah (Pier Lorenzo Pessah)]

no one has found the same issue?? how do you cover this case?

[vishvesh (Vishvesh kakkeri)]

this has been reported a couple of times but currently no proper fix

Battery failsafe on Qland

Hello all, i have been working on my Quadplane for sometime now on the arduplane 4.1.5 stable and has been flying pretty well. Recently i have come across a peculiar problem that i believed was resolved on arduplane 4.1 but was encountered on my recent flight. After completion of the mission of around 90mins i initiated an RTL, the quadplane completed the whole land sequence and transitioned into the wind. On transition as the current consumption increased and the voltage sagged the autopilot…

[Lorenzo_Pessah (Pier Lorenzo Pessah)]

maybe @tridge can help?

[Chris_Heintz]

The devs don’t consider this to be an issue. The workaround is Q_RTL_MODE = 1, but it comes with drawbacks.

Battery failsafe on Qland

The workaround seems to be to set Q_RTL_MODE = 1, but that prevents you from using RTL as a holding pattern and doesn’t help if you are attempting to land or fly as a quad away from the home location. This has been discussed, but the devs don’t seem to see it as an issue

[tkoivuro]

I would love to hear explanation why this is NOT a safety issue.

Currently battery failsafe is completely unusable and dangerous for vtol operators.

[Lorenzo_Pessah (Pier Lorenzo Pessah)]

I’m glad that I’m not the only one sharing concerns about

[Chris_Heintz]

It’s definitely a safety issue and appears to be unmitigated with the default parameters (Q_RTL_MODE = 0 by default). This is the best explanation I got: Quadplane: Battery Failsafe in Q modes causes transition to fixed-wing RTL. · Issue #17617 · ArduPilot/ardupilot · GitHub

The workaround of Q_RTL_MODE = 1 works, but only if you only operate in VTOL modes within the the radius that QRTL uses. Maybe rally points would be a suitable workaround for VTOL operation away from the home location?

Other discussions of this issue:

QRTL instead RTL below certain altitude

no one has featured the same issue?

Plane 4.1 stable

EDIT: This seems to be expected and accepted behavior with Q_RTL_MODE=0, but that does sound like a bug with Q_RTL_MODE=2 as you have it. Quadplanes variety of modes significantly complicates the desired failsafe behavior, but it seems like most of people’s issues would be solved by a bit that has the failsafes trigger QLAND instead of RTL if the mode is a quad mode. That would only be an issue for people who fly in quad mode in an area where they can’t emergency land.

[Lorenzo_Pessah (Pier Lorenzo Pessah)]

This has been finally fix with latest update Plane 4.3 stable release - ArduPlane / Plane 4.3 - ArduPilot Discourse

[Chris_Heintz]

I don’t think so, it looks like it still requires

Q_RTL_MODE=3 (approach)