This morning I installed Arduplane V4.1.2 on a Nano Talon with airspeed sensor. During autotakeoff, the plane maneuvered abruptly, then crashed. Perhaps someone could take a quick look at the log (82%) and identify the problem.
https://drive.google.com/file/d/1iQRx8kAkzQriox28R4sS-LNq0DClpHcz/view?usp=sharing
https://drive.google.com/file/d/1zj3wH2KjX7cr3YCquqzfqdorayhJnn2B/view?usp=sharing
That file you shared is a .tlog, and doesn’t tell us too much. Can you share the .bin log from the plane?
Hi Allister,
I uploaded the .bin file at your suggestion. Help interpreting would be much appreciated.
V/r,
Ron
Within a second of the plane starting to move it began to make an un-commaned pitch up. It looks to me like the V-tail was moving to correct however the speed was still very slow and wasn’t enough to prevent the subsequent stall.
I don’t see any smoking gun in the logs. Given how quickly it pitch up during take off, and the following pitch oscillation after the first stall, I’m thinking it’s either a mechanical failure of the V-tail control (servo, or linkage, etc), or something shifted aft and moved the C of G too far back.
One thing I did notice, (I’m guessing you’ve flown this plane already because the PID values aren’t default) I would suggest setting SERVO_AUTO_TRIM,1. This will trim the plane up for all modes. Also if you notice servo trim values are at an extreme it may be a clue that the C of G is not correct (again, assuming the plane is mechanically in trim)
Hi Ronald,
I know the problem from the Opterra 1.2. I assume that you are throwing the plane up too steeply. Almost 30° are too much. This will cause the nose to be controlled downward so that more than 10 m/s can be reached. However, the control swings up so that on the next “wave” with almost 50° pitch-up and again strongly decreasing speed the airplane tilts over the wingtip. Throwing much more flat , especially in weak headwinds, helps best in my experience.
Rolf
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Thanks Allister for your very insightful comments. Indeed this plane had been flight tested and tuned previously. I examined photos of the crash and noticed the battery was sliding out of the mid bay section. (Normally the battery would slide forward, not aft, in a hard landing. The pilot had neglected to tie down the battery before takeoff, so it slid from the forward bay to the mid bay during the initial phase of climb out. Next flight test the pilot tied the battery down correctly and the plane climbed out properly.
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