I tried the TAKEOFF mission item for the first time a couple of days ago and experienced a hard belly landing into the grass instead.
I believe it’s due to TECS_TKOFF_IGAIN=0 in the default parameters causing elevator output to almost freeze, so the plane does not gain pitch fast enough.
I would like to ask if it is intended that this value is zero because it basically disables the pitch error correction during takeoff?
TL:DR
When I check elevator movement in FBWA, the elevator actually does move almost the complete way upward on stick pull and plane pitch movement in self stabilization.
When I switch to Auto, I see that the pitch demand goes to 15deg as expected but the elevator does not move up significantly.
After I changed TECS_TKOFF_IGAIN=0.2 , the elevator does move up all the way until I move the plane upwards towards the 15deg, then elevator goes to neutral.
The plane is a sub 250g ZOHD Drift which is has been tuned twice with Autotune while there was no wind.
TECS values have been set manually according to guide.