QuadPlane transition in case of in-flight failure

I’m starting with ordering parts for my first QuadPlane build. I’ve always been interested in improving the robustness of my airplanes in case of equipment failures. So I have a question if AP is reacting to possible problems by doing transitions in quadplanes? In both directions:

-to plane if one of the quad motors fails
-to quad if a plane servo seems not to respond

It’s vital to do it automatically, as the human reaction is way to slow, as it can be easily seen when dropping a load from a multicopter - more or less maintains level flight in alt-control modes and shoots to the sky in the stabilize mode, even if you reduce the throttle at the same time as releasing the cargo.

yes, see Qassist

no, because it is not safe to assume you can suddenly start flying forwards. That would be quite a unsafe thing to do. If you high up with lots of space, sure. But if you just about to touch down you really don’t want it to suddenly transition to forward flight. Its safe the other way because your stopping on a path you were already on rather than going somewhere new.

Thanks for pointing to Qassist, I’ve not known about it. But it seems to be something different. It’s based on attitude errors. So will it trigger when the plane will get into a windshear/wind gust? And will not trigger until the critical angle is reached, even if the AP would know beforehand that something went wrong? (for example, maxing out a servo output with no response). Am I right here?

So why not make it possible to switch this feature off/on depending on the obstacles at the launching spot? Flying UAVs will always be about responsibility…

I think you missed Q_ASSIST_SPEED, which the user sets to a value near the stall speed. The quad motors will provide stability and lift assistance in fixed wing modes. Zero means no assistance except during transition.

You can use the Geo-Fencing feature for this avoidance.


Not always in such circumstances the airspeed goes below the stall speed. Once I had the elevator servo failure and the speed remain neither very small nor very big, but the airplane was not controllable.

You mean GeoFencing in relation to QuadPlane launch and transition to the plane mode in case of a quad motor failure?