First, Tridge and WickedShell, thanks for your time looking at this, I do appreciate it.
Sorry for my delayed reply, I forgot that this forum does not send Email to warn you you got an answer to your thread (by default). Kind of a misfeature…
Random replies:
-
I had TRIM_ARSPD_CM at 15 and ARSPD_FBW_MIN at 12 last time we talked Tridge, and I seem to remember that you recommended I lower TRIM_ARSPD_CM to the same value than ARSPD_FBW_MIN, so I did before this flight and crash.
-
You did mention I got as low as 7.5m/s, as per my reply in the bug, that’s not what I found in the logs, nor do I believe it’s possible. This plane stalls below 11m/s. But as agreed, the airplane did get too slow and did at least for a while need pitch down to maintain flying airspeed. The AP made sure it never stalled.
-
You’re correct about full throttle being only 80% per my request in the config, I had half forgotten about that, but at the same time on that motor 80% was mostly maximum thrust anyway, and I didn’t want the motor to be overstressed and burnt during normal flight. You could make the case that allowing takeoff power might be allowable for GUIDED with a minimum altitude deck, would be a good thing, but that’s half a detail.
-
Sorry, I forgot to give my channel mapping
o CH01 : Right Aileron
o CH02 : Elevator
o CH03 : Throttle
o CH04 : Rudder
o CH05 : left aileron
o CH06 : R flap
o CH07 : L flap
o CH08 : OSDCmg: up 12V+cams off, mid: 12V on, down: GUIDED. 2 mode flips: OSD rotate
o CH09 : FPV Camera L/R (S2)
o CH10 : free
o CH11: RSSIQual from RX
o CH12 : Ardupilot Mode Switch (6 position switch mod)
I’m pretty sure that both flaps were full down due to manual passthrough -
Having override set in manual, yes, it’s a reasonable idea. I kind of wanted GUIDED to save me in case I did something stupid, and lost control, but right now it’s more likely to crash my plane, than me, so manual removing the geofence is not a bad idea
-
Putting crow flaps actually causes my plane ot pitch up, I have a crow flaps to pitch down mix. However I never fly with flaps only (my controller is not setup for it), so I cannot swear to you that flaps cannot cause pitch down, but I’m pretty certain they won’t because every single full size plane I’ve flown requires trim down as you add flaps, in other words flaps cause nose up.
However full flaps down on that plane will definitely add a fair amount of drag (that’s the point), so trying to fly back up with full flaps should be possible, but harder. Given that the airspeed went as fast as 26m/s with flaps down, I assume some of that energy could easily have been used to fly at least level, or back up.
I read your detailled analysis Tridge (thanks), and you also found that keeping pitch down was harder with the flaps, which agrees with flap causes pitch up. On that plane full throttle also causes pitch up, but not horribly so. When I fly in FBWA or CRUISE, the AP seems to handle that condition transparently and keeps things in check ok.
So, I do think the flaps caused loss of pitch control much more than throttle because I used full allowed throttle in FBWA/CRUISE many times without problems
Tridge, to see if throttle was more an issue than flaps, can you compare with
marc.merlins.org/tmp/6_GUIDED_st … _crash.BIN
from
github.com/diydrones/ardupilot/issues/3357
where I went from FBWA to GUIDED and a similar looking issue happened except no flaps should have been involved then.
This will help validate (on the same airframe) if your analysis and fixes would have helped with the issue there too
