We had a crash with one of our planes. The plane was flying normally in manual and stabilize mode but soon after switching to LOITER mode, it tried to roll quickly and kept on losing altitude, so I tried to switch back to Manual mode but it was too late to recover. Please help in analyzing the log file. Thanks
I had a quick look:
Looks like take off happened without a good GPS signal.
In Loiter mode a good GPS / healthy GPS is vital - as this wasn’t the case the system tried to over compensate the moment Loiter was activated. This resulted in some sudden changes in power settings and an increase in current by about twice compared to average earlier value.
→ Very important to have good GPS signal / health prior to takeoff whenever a GPS reliant mode will be used. (i.e. Loiter, Auto, RTL,…)
In the logs it shows 13 sats when switched to LOITER. and good GPS health and SAcc. Can you please tell me how you came to the conclusion that I had bad GPS signal? Is there any other parameter that I missed?
Was someone using trim on this controller? Through out the flight there is always high values of pitch input and when the input levelled off (usually meaning centre stick position unless you have hands of steel) the input was at 1641us, not the 1515us of RC2 trim value. This means the flight controller always things creating an input, even when you think you aren’t.
If trim was used then verify the mechanical trim and adjust as required so it’s not needed. Or verify that it wasn’t to offset some C of G issue. I see SERVO_AUTO_TRIM is already on so it will do the trim work for you from FBWA or some auto mode.
HDOP was only between 1 to 0.8. The lower the value to better the GPS signal is.
…Doesn’t matter how many satellites it receives if the data from those satellites isn’t any good. That’s way the HDOP value is so important.
I won’t take off on a flight unless it is down to around 0.6 or lower.