Hi!
My goal is to simulate a custom frame, with a custom flight mode with SITL in Gazebo and QGC.
I have made a new vehicle based on the ArduSub directory. Here I want to create a new frame and I followed this post: ArduSub SITL Custom frame, but used the already custom frame (Enum 7) as my new frame. In addition, I only have 3 thrusters, so I skipped point 5 in the post.
I also added “FRAME_CONFIG 7” in .parm file linked to the new frame.
I have not bothered to build the QGC again, as it is not strictly necessary(?) since I used the “built in” custom frame.
I have downloaded and installed Gazebo from this guide: SITL · GitBook.
From this post Custom Frame ArduSub SITL with Gazebo, I removed 3 thrusters, and updated the pose for the three first thrusters from the BlureRov2.sdf file in bluerov_ros_playground/model/BlueRov2/. In addition I removed <control channel=“3”> ,<control channel=“4”> ,<control channel=“5”>.
I am getting some strange behavior when running sim_vehicle.py -f gazebo-bluerov2 -L RATBeach --out=udp:0.0.0.0:14550 –console. When I arm the vehicle, it drops towards the bottom. When I disarm, it stops. Is there anything I have misunderstood or need to check/do to get this running?
Additional info if relevant:
I use “none” in the sensor settings in QGC since the Pixhawk are going to be mounted like that on my vehicle.
Let me know if anything is unclear.
I appreciate all feedback, tips and suggestions 
