Improving landing of turbine plane

[Lee_YL (Lee)]

Hi,

I am working on improving a turbine plane landing. It successfully landed once which is an accomplishment! On the same run, I took off and tried landing again, but the plane had a large pitch down (-6deg) near the ground which made forced an abort landing. I am using Here4 gps and RTK correction to improve the height estimate.

Both landing are on the same log file. Would appreciate suggestions on how to improve the landing. In particular:

• how can I avoid the large pitch down close to the ground? I suspect it is because h is above demanded h. Do I just flare higher/earlier

• Not sure why TECS_APPR_SMAX does not seem to be followed during approach

• how to reduce the large oscillation in pitch during approach, should I increase TECS_LAND_TCONST?

Here is the log file

00000115.BIN

Thank you

[jinchengde]

maybe you could reference the discuss in

Automatic landing failure to establish flare resulted hard touch down

Hi guys, I attempt to use automatic landing, but there was a obviously hard touch down, after check the log, I found the aircraft didn’t establish the pitch angle during flare phase, causing touch down with a very high descent rate. BTW, I used rangefinder to achieve more accurate altitude control aircraft start to flare at 2m in log “2026-01-31 16:00:11.755 Flare 2.0m sink=1.92 speed=15.1 dist=18.9“ [屏幕截图 2026-01-31 192547] so we could see when the vehicle start to flare, TECS.dhdem star…

[Lee_YL (Lee)]

Thanks for the reference, I believe the dropping of dhdem during flare contributes to the problem on my aircraft too.

I am trying to merge the code change and build the firmware myself like you did, but I am struggling with the steps. In particular, I managed to build and upload arduplane 4.8-dev onto cube orange from my local repo, but I am not sure how to build and merge changes using arduplane 4.6.3. Would you be able to share any useful weblinks or steps for this? Thank you

[jinchengde]

1. clone the code
2. switch branch to tag plane-4.6.3
3. merge the fixed code
4. done

[Lee_YL (Lee)]

Hi,

Thanks for the guidance. Do the steps below look correct?

I managed to build the custom firmware with these commands in WSL ubuntu:

git clone ‘https://github.com/ArduPilot/ardupilot.git’

cd ardupilot

git checkout Plane-4.6.3

git switch -c Plane-4.6.3

git branch (to check current branch)

git fetch ‘https://github.com/ArduPilot/ardupilot.git’ pull/31610/head

git config –global user.email “myemail”

git config –global user.name “myname”

git cherry-pick FETCH_HEAD

git submodule update –init –recursive

Tools/environment_install/install-prereqs-ubuntu.sh -y

. ~/.profile

(shutdown and restart WSL ubuntu)

./waf configure –board CubeOrangePlus

./waf plane

(upload build/CubeOrangePlus/bin/arduplane.apj to board using mission planner)

Thank you