Originally Posted by
timprice
Good coordination well practised, seems like they know what they are doing.
No risk to anyone else, whats the problem?
At first I thought: Lunatic doing such maneuvers in a Robbie. Looking closer at the videos I noticed that the rotor disc never appear to move out of plane to any significant degree. Given the freely teetering head that indicates to me they knew indeed what they were doing. No unloading of the disc. No maneuvers against inertia of the fuselage.
Rotor RPM appears to be under control continuously. Since Rotor RPM and Disc tilting against the stops are the two big fatal gotchas in a Robbie I would say it looks very controlled and pretty safe (for a display).