Logs of death spiral

I heard that sometimes this group will take a look at logs of flights and see if they can offer suggestions about what has gone wrong.
Quick background: we fly the Zephyr II flying wing platform from RiteWing:
We have flown with APM 2.5 several times in NAV mode with few problems.  However, in STAB mode we have twice experienced a "death spiral" where the plane unexpected and quickly rolls into a spiral towards the ground.  Our awesome pilot has saved it both times.  The attached logs are from both a June flight and an August flight.  In the June flight we though our bank limit might be the problem, so we scaled it back from 65 to 35 degrees (see attached paramaters file for the 2nd death spiral flight in August).  However, we still experience the problem from time to time.
Most recent August flight was using APM:Plane v 2.73.
Anybody have any ideas what we might be missing?

Michael Day



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  • I took a quick look, and the way I see it you stalled it. Airspeed went as low as 7,5 m/s, you pitched up slightly and stalled the plane.
    When you tip stall a wing plane (such as the Zephyr), it will most likely result in the well known death spiral. (google it)
    Easy ways to remedy this:

    1: Fly faster
    2: Move CG forwards.

    3: Go easy on the control surfaces. You might want to reduce throw a little bit.

    And some general advice: Don't try to fly tight corners with your wing plane, it isn't built to do so.

    Have fun flying!

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Aug 25