This is the briefing given by Carey Bond at Heli Expo 2009:
And by Kevin Bredenbeck at HeliExpo 2009:
Also a general video of the potential of ABC in LTH applications:
The point i found most interesting was the explanation of the twitchy control of the first flight. At that time the FBW was direct stick to head control with no feedforward/feedback stability augmentation. The pitch and roll control was actually slightly higher than had been anticipated by the predictive processes used to develop X2 control systems. The flight has since been analysed to understand the actual pitch & roll moments for a given swashplate movement which will then be incorporated into the control algoritms.
An interesting insight into the world of flight test there. Even more so as the rotor dynamics head into ABC regime. This is likely the main reason the flight test is being done in three distinct speed phases.
What i will be interested in understanding is how the control for the pusher prop developes to make it intuitive to use. Especially once the main rotor has gone into autorotation. I would imagine that collective would be automatically trimmed to keep Nr constant while TP varies thrust. I would imagine that prop pitch will also be automatically trimmed so that TP is only controlling engine power with twist grip.
Hopefully future briefs on this amazing machine will be just as informative...
Last edited by Graviman; 14th Nov 2009 at 23:01.