Hello all,
I’ve returned to RC from a 25 year break, and have been doing LOS flying with helis, planes and small quads.
This winter I got a Pixhawk that went into a Bixler 3. The Bix3 isn’t as spacious as you’d expect…
So today my plan was to maiden her, just manual flying to see that the airframe was ok. Otherwise fully loaded.
I had the wheels on it so the start was ROG.
The start went as expected, but it felt a bit heavy due to all the things crammed into it and antennaes sticking out everywhere.
When in the air I tried to throttle back but it kept on going at full tilt, I thought I’d have to wait for the ESC to cut power and hoped there would be enough power for the servos and controller to glide it down.
All other controls worked but felt limited.
Did like 15 or so “circles” around the field before trying to change flight mode.
I did a quick change from manual to RTL and back to manual, and then gained control of the throttle again.
Landing went well but wasn’t pretty.
Could you help me figure out what caused this?
I had to remove compass from pre arm checks for it to arm. Probably bad config of orientation of internal compass.
OrangeRx sbus receiver with sat.
M8N GPS
Telemetry to MissionPlanner GCS.
@RRacer,
The reason the throttle was on full was it was trying to reach your RTL altitude of 100 meters. It didn’t manage to reach that altitude as elevator stick input was forcing the aircraft lower.
The STICK_MIXING parameter was set to 1, which means pilot stick input was able to override the automatic navigation in RTL. It doesn’t however override the altitude controller (called TECS) which was still trying to reach the target altitude set in ALT_HOLD_RTL (which was set to 10000, which is 100 meters).
It is quite unusual to be actively flying the aircraft with stick inputs in an autonomous mode like RTL. The STICK_MIXING option is meant for emergency course deviations (such as dodging another aircraft), not to fly the aircraft. If you want a mode where you have navigation control then you should use FBWA or CRUISE modes.
Good luck with your next flight!
Cheers, Tridge
Thank you for your input, and I am sorry for not checking in for quite a while.
I took off in manual mode, and as a last resort I flicked to RTL and back immediately, so I really should have been in manual. The reason for the quick toggle was that I had not set up the other flight modes and was not sure what would happen.
Anyway, the toggle let me regain control of the throttle.
Yesterday I went out for a second run. No changes at all to the plane or pixhawk. I know, I should really had investigated this behaviour…
I took it up in manual mode. Throttle worked as it should. When I had it a few mistakes high I switched to loiter mode, and it started to make a big, steady circle. Much steadier flying that I managed in manual, as it was windy.
Then I tried RTL which worked as expected - it came back home and started to circle.
Next run the stuck throttle problem appeared again, in manual mode. I didn’t freak this time as I knew how to fix it, but it gives you an uneasy feeling when it does things it shouldn’t.
A quick toggle of flight mode and all was well.
Now I had a few waypoints set up, which worked perfect.