Sounds like the problem is that the rotor was stable, but the rotorcraft was not! I would expect the left side of the disk to produce no lift, and the right to have to be fully flattened in pitch so it had no lift either, (and the wings providing the necessary lift).
The big question is why they encountered this circumstance as an unplanned event. Bad ju-ju for a flight test to discover a bad behavior (poor rotor rpm control, in this case) that is so bad they lose the helo as a result. It is a miracle that the crew survived, and just that.
None of this takes away from the interesting and possibly important work the Cartercopter guys are doing. I met Jay Carter at an AHS symposum once, and I know he is serious and hard-nosed in his engineering approach to the problem. No flaky pie in the sky thinking going on down there.
I have contended that the best way to explore the high speed regime here was to force the rotor to get there while it was not the prime lifting surface. In other words, strap the rotor to a bigger airplane and step out in speed while messing with rotor rpm, and measuring all the rotor forces and moments and control responses.
Last edited by NickLappos; 21st June 2005 at 19:57.