Thanks for the PDF links Dave. I will read them with interest. I admire your sticking to your guns about intermeshers.
For reference purposes, i remain unconvinced about the efficiency of a practically sized interleaver in hover (not to mention drivetrain complexity/reliability). Intermeshers (feathered retreating) make more sense to me, and i suspect Nick (in the light of the X2) will stick to ABC coaxials. Flight aerodynamics and cost will decide.
Hover power requirement really is the limiting factor in helicopter design, which was highlighted very well in the post (pilot let speed bleed off - potentially fatal in a fixed wing):
http://www.pprune.org/forums/showthr...hreadid=142923
A machine which has an even steeper -ve power curve from hover to foward flight (ie transition) will be more likely to suffer this kind of mishap. The effective foward flight "wing span" of an inteleaver will be higher than it's intermesher or coaxial counterpart, leading to false pilot perception of hover capability in high altitude approaches.
Regarding Lockheed style gyro stability (i still feel privileged that Lu took the time to explain the AH56 technicalities to me), i will only comment that reading the following thread made me think about helicopter flight in IFR. They are difficult, without experience, to hover in VFR. Having flown gliders in cloud, i hate to think what an R22 would be like (deadly i suspect):
http://www.pprune.org/forums/showthr...hreadid=193920
Note kissmysquirrel's comment "Good job he wasnt in an R22 then!!"...
My thought on reading this was that a Lockheed gyro system (ideally with "rigid" head) would significantly reduce the likelyhood of accident. The stick could also have a mass on it's base (or somewhere in control linkage), so that hands-off the helicopter would by default right itself into a stable hover. This mass could be trimmed, allowing inherent speed stability. I remain convinced that this system would be both simple enough for a light heli, and would significantly reduce accident rates.
There is of course nothing that says you can't fit large horizontal and vertical stabilisers. I suspect that this will go a long way to help your passive stability machine. Even with these the machine will never demonstrate the sort off hands-off controlability, particularly in hover, that i suggest is required to really open up the light heli market.
The addition of a weak servo on the collective for autorotation entry, would be the final piece to low accident rates. Since auto throttle is common, this is also easy to implement as part of the same system.
Sorry if this has dragged your original thread too far off topic - i genuinely do enjoy the future rotocraft debate...
Mart
[Edit: in response to the edit in Dave's previous post!
]