First off, here is my log, sadly 0.03MB larger than the limit here allows, so I had to upload to an external service, this link will be active for 7 days, then the service deletes it automatically - DOX.bg - Файл организатор
Basically I was running a mission, the plane is a Flying Dragon 2160 VTOL model, flies amazingly well as a plane, no issues for over 15 flights. At the end of this particular flight as usual I was coming in for a landing, and about 60-70m from me I switch from FBWA to QHOVER for the transition, everything looked good for a while, it was spinning the VTOL motors and I expected it to ramp them up at some point and VTOL to take over as the plane was slowing down, but instead of that it just shut off the VTOL motors and dropped to the ground from about 3m. Luckily there was no major damage, and nothing a bit of fibre tape can’t fix on the spot. I had no idea what had happened, I checked all the wiring, the params, the log, nothing stood out, so I proceeded to do another 2 flights, no issues at all, perfect transitions every time, but this is still bugging me, so I turn to you now.
Any insight into why it cut the VTOL motors mid-transition as the plane was slowing down would be greatly appreciated! Thanks in advance!
The parameter LOG_BITMASK was set to 0. So the log is almost blank. It’s got some messages and parameters, but that’s about it. Try setting it to at least the default of 65535. That will make log files bigger but at least there will be some data to work with.
Sorry to hear about the crash. Wish I could offer more.
One thing I see in the messages is that there were some throttle (RC) failsafes, and at the end of the log a lot of mode switching. Is there a chance of some kind of radio issue?
Well darn… I have no idea why the log bitmask is set to 0, I have not done it myself, must be what is default for the Orange Plus FC I am using as it also had some other params set to very weird values, the serial ports were all set to some scripts, so nothing connected there was working properly before I switched them to the correct values. I will have to enable logging then.
As for the modes switching, I have a set of modes I go through to make sure it transitions from VTOL to forward flight fully because sometimes, even though I’ve dropped min airspeed pretty low, have disabled assists and weather vaning, etc., I am not using an airspeed sensor, it would still not transition from QHOVER to FBWA and would just keep spinning all motors, so now IF it doesn’t manage to transition even when reaching speeds of 90km/h, I just flip it to manual and then immediatelly back to FBWA, and then after I gain the altitude to Auto so it can run its mission. After the mission is done I go to FBWA… although sometimes it needs to go to manual and then to FBWA before switching out of RTL, and at the end you can see me switching to QHOVER, it dropped to the ground and I flipped to Manual just as it was touching down so as to force the front motor to stop as well, then I disarmed. There may have been some failsafes, not sure as I am having issues with the OSD I am using, plus I currently do not have my Dragonlink system bound with telemetry, only one way communication.
It’s a good thing that it fell from a height of 3 metres and not 40 metres and that the damage was minimal.
Unfortunately, we can only speculate based on the rudimentary log data. DCM did record roll/pitch/yaw and you can see that the roll and pitch suddenly change almost abruptly at the end, which goes hand in hand with your description that the quad motors suddenly stopped. Now you have no idea what came first. Egg or hen? Unfortunately, there are no other records, especially the power consumption values and motor outputs, as this would indicate whether it was a power supply problem. On the ground you had to disarm to switch off the font motor ? If the quad motors are powered differently to the front motor, I would almost check for a problem of the power supply of the quad motors. You can see that the flight controller was supplied with power the whole time. The power supply plan of the aircraft would be interesting to see if there is a possibility that only the power supply to the quads fails.
Well one battery powers the whole thing. The lead from the battery goes to a distro board, which then in turn powers the puller motor, and each of the wings, and has a harness with leads to power other stuff. Since I do not have a high current sensor for the Orange Plus I do not have the VTOL or puller motor power going through it, I use it only to power the Cube. Nothing really was disconnected but I find it weird that I’d lose power to the VTOL motors, but servos, FC, etc., would keep working, IF it was a power issue. Also feels kinda freakish to have both wings suffer VTOL power loss when they are coming off of two different connectors out of the PDB board. I will enable the logging, but I certainly hope this won’t be a repeat situation, but does sort of give validity to my decision to do transitions at low altitude!
