I’d appreciate your help reviewing my log (link below) to understand a very odd and seemingly senseless maneuver by PX4 during an autonomous takeoff of a fixed‑wing aircraft.
Log link:
At around 8:26 (hh:mm) in the log, the plane executes a very steep turn that makes no sense to me. This behavior seriously concerns me about PX4’s reliability for fixed‑wing operations. If the system is supposed to perform a failsafe, what is the purpose of this extremely sharp turn? Is there no mechanism controlling that? It feels like utter nonsense!
Could someone examine this log and provide a logical explanation for why PX4 behaved this way during that takeoff? Thank you!
@Ertugrul_S PX4 is more than fine for FW flight… Several thousand flights can confirm that, the vast majority completely autonomously, including autolanding.
50º is fine for roll, we used to keep it at 55 and only recently set it to 45 but it will command whatever is in FW_R_LIM aka 50 by default. This then requires you have your speeds well known and tested. If you bank at 50 deg than stall increases by 24.8%. PX4 knows this and speeds it up but if you are straddling too low of a speed, etc nothing you can do.
There are only two things they could have happened (let’s exclude rare edge cases), either you stalled the wing (go do a stall speed testing at different weights and log it all - just ensure you have a lot of altitude), and secondly, you broke something under the stress, aka a horn, servo, etc. A distant number 3 would be something like a suddenly clogged airspeed but we’d see that in the log.
@JulianOes i wonder if we should add a stall indicator to flight review. when you see actual vs sp diverge and coincide that with airspeed drop, 9 out of 10 times it’s a stall. Especially in roll axis before pitch. Even if pitch drops suddenly you will generally see a wing drop bec wing will lose lift etc.
