APM 2.6 - Flying Wing Crash - Spiral of death

Hi Everyone,

Very weird crash today. I have 12-15 flights all flawless before this incident. When it occurred I immediately thought I lost a servo - but upon inspection both servos were fine. Watching the video (below), I did not input the left roll that began the spin. I tried to switch to ‘manual’ but that made no difference; it’s like I had no attitude control what-so-ever.

-APM 2.6 Plane 3.2.1, GPS with external compass
-3DR power module
-APM airspeed sensor

Here’s a video of the crash - winds were about 10-15mph hitting the aircraft from the right side. I left the sound in, so maybe lower your speakers before clicking the link:

Click here for logs - both telemetry log from ground station & dataflash log. The spiral begins about 36% into the telemetry log (.tlog).

Any help would be greatly appreciated!

just a correction, i’m running Arduplane 3.2.3 (not 3.2.1)

no one? just want to figure out if it was just a stall (pilot error), or something else going on with the autopilot…

Sorry for your crash…I’ll take a stab at it…
Seems to be a roll mechanical failure in the log… The roll diverged really quickly to full but the Desroll was mirrored with a strong action the opposite direction… The pitch and despitch followed together… Going to Manual would have no effect with a locked servo… you also see a current spike at the spot… I would suspect an aileron servo as the culprit… Even tho they might have been okay on the ground I have seen servos go full tilt when under stress…

thank you Sandyem16 for your input! I really did think it was a servo failure, so I tested them vigorously and just couldn’t get them to lock up or do anything odd.

I also posted this incident on the diy forums after not getting much from here; the general consensus is that I went into a tip stall. I attached an image which plots my baro alt, gps speed & airspeed. It shows a steady climb, which at it’s peak I killed the throttle (my error), putting my airspeed to about 9 m/s right before the spiral. Also I noticed my airspeed sensor showing a 4-5 reading while on the ground with the pitot covered… I’ve ordered a replacement airspeed sensor to test, and in the meanwhile increased my FBW min speed to account for this ‘offset’.

hope this helps someone in the future!

My crashes STARTED almost identically to yours however it did NOT result in a spin.
Reading this, I’m thinking my servos are not behaving properly and momentarily going full deflection. Resulting in a left spiral of death both times…

I was able to recover control in stabilize - not enough to dodge the ground though…

I do NOT buy that your, or my, sharp rolls were stall induced…


Using APM2.6 with arduplane 3.3.0
Yesterday I had a similar crash.

After a 20min flight my flying wing (Phantom FX-61) started to tip stalling!
I was flying in stabilized mode and it tip stalled one from which I could recover.

Right after that moment of panic it just happened again…
It tip stalled and started to spin like crazy.

I tried to any forms of recovery I could think of: ailerons left/right, elevator up after some gaining some speed, I even opened throttle for 1 sec on my way down to increased the speed… nothing.

When I was about to hit the floor as hard as it could, I applied full down elevator to which the wing responded and started to level as in inverted flight… WTF!
At least it helped to reduce the damage from the crash (mostly just canopy, wing joints and camera pan servo) as it landed almost on its back…

I was in stabilized mode when all of this happened.

Can someone help me analyze the log file?
Was this a tip stall or APM malfunction?