I know that APM supports automatic takeoff, but from my reading on the matter, it wants you to program the takeoff as a mission from the ground control station.
This is way too much work, I fly all my APM craft without a GCS at all, I want to just go somewhere and fly. As such, when I got my new Zephyr II flying wing, I wanted a simple and easy way to automate hand-launching that takes advantage of the APM’s autopilot.
Enter my Taranis!
I set up a switch on the Taranis which is set to ‘Replace’ 3 channels – mode, elevator, throttle.
It changes the mode to FBWA, sends full ‘up’ elevator, and sends 100% throttle with a ‘Slow Up’ of 8 seconds – meaning it goes from 0 to 100 over 8 sec.
FBWA is the ideal mode for a hand launch, as it converts stick inputs into degrees and climb rates, relative to the airframe’s current position.
This means that full ‘up’ elevator results in a nice smooth climb at around 2meters per second, and the wings are kept level for the duration. The FC is constantly analyzing the altitude of the plane, and as such it only gives enough elevator to maintain a climb.
You should note however, that the FBWA throttle is capped by the THR_MAX parameter, so be aware of what this is set to before you try a launch – you want to have plenty of power!
Here’s the resulting launch video: