With the changes made, batteries charged and the model and telemetry checked for anything abnormal we set off for flight 2.
The take-off was much more relaxed, with it being in trim. It lifted off by itself just before I initiated the rotation. Climb away was smooth and positive. On downwind, the gear was retracted and the model became much smoother in roll. I flew a circuit gear up with take off flap selected and then selected flaps up on the next down wind leg. After re-trimming I initiated a right descending turn to fly back up the runway.
However, at about half-way around the turn, with no warning the model snaped to the right and entered an aggressive unrecoverable spin. Luckily Steven called out to kill the engines and I got them off just before it descended below the tree-line, avoiding a post-crash fire. The debris confirmed that there was no significant forward speed on impact, with all the parts contained within the planform of the model.
It is clearer on the iphone, but from the video, it is clear that the model snaps to the right and enters a spin - what I still cannot work out is the cause - I do not recall pulling the model in the turn, it was a gentle descending turn and GPS shows that it was doing just over 100mph, the same as the rest of the flight. Both engines were running and the throttle was unchanged since throttling back after take-off.
I know the full-scale was very unforgiving at slow speeds, so potentially the model has retained some of these traits based on its overall configuration. I incorporated 3deg of washout into the wings to avoid tip-stall. Potentially the T-tail got blanked by the fuselage, but with a forward c.g. I would have thought that even with a tailplane stall, the nose would have dropped.
Lots to reflect on before deciding what to do next with the Buccaneer project.
Paul