Found my bravery, so I took this new code outside and flew it. And it worked! Vertical take-off and none of the rapid horizontal ‘drift’ into walls or railings. Sadly it showed I needed some more PID tuning, as she was see-sawing on the X axis, and then exceeded her temperature limit, so died midair, still rotating. She hit the ground on her side at pretty much the point she took off from (!), stuck a blade in the ground and then continued rotating until she was horizontal. That was the last of my 11 x 3.7 blades broken, but I have another two sets on order already, but with the state of the postal service at this time of the year, there’s no guarantee they won’t arrive until 2015!